Date post: | 11-Feb-2017 |
Category: |
Technology |
Upload: | pushpa-rai |
View: | 945 times |
Download: | 12 times |
PREPARATION AND QUALITY EVALUATION OF
GINGER WINE
by
Pushpa L. Rai
Central Department of Food Technology Institute of Science and Technology
Tribhuvan University, Nepal November, 2009
ii
Preparation and Quality Evaluation of Ginger Wine
A dissertation submitted to the Central Department of Food Technology
in Tribhuvan University in partial fulfillment of the requirements
for the degree of M. Tech. in Food Technology
by
Pushpa L. Rai
Central Department of Food Technology Institute of Science and Technology
Tribhuvan University Dharan, Hattisar, Nepal
November, 2009
iii
Tribhuvan University
Institute of Science and Technology
Central Department of Food Technology Central Campus of Technology, Dharan
Approval Letter
This dissertation entitled Preparation and Quality Evaluation of Ginger Wine
presented by Pushpa L. Rai has been accepted as the partial fulfillment of the
requirements for the M. Tech. in Food Technology.
Dissertation Commettee
1. Head of Department __________________________
(Assoc. Prof. Dhan B. Karki)
2. External Examiner __________________________
(Prof. Dr. Ganga P. Kharel)
3. Supervisor __________________________
(Assoc. Prof. Dhan B. Karki)
4. Internal Examiner __________________________
(Lecturer Babita Adhikari)
Date: 24th November, 2009
iv
Acknowledgements
I would like to express my hearty sense of gratitude to Assoc. Prof. Dhan Bahadur Karki,
Chief of Central Department of Food Technology, Hattisar, Dharan. He encouraged me to
carry out this dissertation and provided valuable insights to coordinate the sources of
information and to proceed the research work. I would like to express my gratitude to him
for his moral and technical support with frequent inspiration and supervision.
I extend my profound gratitude to Assoc. Prof. Basanta Rai, CCT, Hattisar, Dharan, for
providing me GenStat software programme. I am also grateful to Mr. Bhaskar Mani
Adhikari , Mr. Ghanendra Gartaula, Mr. Santosh Singh, Mrs. Meera Shrestha, Mr. Madhav
Prasad Tiwari, Mr. Dipesh Basyal for providing me constant support during my
dissertation work. I express my hearty gratitude to Mr. Sujan Shrestha, Manager, Makalu
Wine Industries (P.) Ltd., Basantapur, Tehrtathum, for providing me true wine yeast for
this dissertation.
I would like to express my hearty thanks to my teachers, all friends, and staff of library
and laboratory, for their direct and indirect co-operation, and suggestions. I express my
affectionate thanks to D. Katuwal, Dharan-11, Sunsari, for providing me constant
inspirations.
At last, I owe my deepest gratitude to my respected parents and my family for making me
able to stand in this position where I am now.
________________
Pushpa L. Rai
24th November, 2009
v
Abstract
Effect of mash TSS (16, 20 and 24oBrix), ginger amount (1, 1.5 and 2% m/v) and yeast
types (Saccharomyces cerevisiae and Saccharomyces ellipsodeus) on the chemical and
sensory qualities of the wines were studied. The wine was clarified using bentonite
suspension (5% m/v). Fermentation mash containing 10% raisin, 20oBrix TSS, 4.5 pH and
1% ginger (m/v) was found to be optimum for wine fermentation using baker’s yeast (S.
cerevisiae) at room temperature (28-30oC).
The average pH, TSS (oBrix), alcohol content (%v/v), total acidity (as g lactic acid/L),
fixed acidity (as g lactic acid/L), volatile acidity (as g lactic acid/L), reducing sugar (g/L),
esters (as mg ethyl acetate/L alcohol) and total aldehydes (mg acetaldehyde/L alcohol) of
the ginger wines fermented by wine and baker’s yeasts were found to be 4.1 and 4.2, 5.8
and 6.2, 7.8 and 8.71, 7.56 and 7.92, 5.4 and 5.88, 2.16 and 2.04, 5 and 6, 45.5 and 40.23
and 30.61 and 23.16 respectively. TSS, total acidity, fixed acidity, volatile acidity, esters
and total aldehydes were not significantly different but pH, alcohol and reducing sugar
were significantly different (p<0.05). Sensory analysis showed that taste and mouth feel
were not significantly different but smell, color and overall acceptance scores were
significantly higher in wine fermented by true wine yeast compared to baker’s yeast.
Bentonite was found to be most effective at the rate of 0.5g/L for the clarification of
ginger wine. The ginger wine could be prepared from the mash having 10% raisin, 20oBrix
TSS, 1% ginger (m/v) and 4.5pH by using baker’s yeast in comparable quality to that
fermented by true wine yeast.
Contents
Approval Letter .................................................................................................................. iii Acknowledgements ............................................................................................................. iv Abstract ................................................................................................................................ v 1. Introduction ..................................................................................................................... 1
1.1 General introduction .................................................................................................... 1 1.2 Statement of problem ................................................................................................... 2 1.3 Significance of the study ............................................................................................. 2 1.4 Objective of the study .................................................................................................. 3 1.5 Limitations ................................................................................................................... 3
2. Literature review ............................................................................................................. 4 2.1 Introduction of Ginger ................................................................................................. 4 2.2 Varieties of ginger cultivated in Nepal ........................................................................ 4 2.3 Composition of ginger ................................................................................................. 5 2.4 Ginger and its health benefits ...................................................................................... 5 2.5 Historical background of alcoholic beverage .............................................................. 6
2.5.1 Brief description of alcoholic beverages .............................................................. 7 2.5.2 Classification of alcoholic beverages ................................................................... 8
2.6 Traditional alcoholic beverages of Nepal .................................................................. 11 2.6.1 Jand ..................................................................................................................... 11 2.6.2 Rakshi ................................................................................................................. 11 2.6.3 Toddy/ Tadi ........................................................................................................ 11
2.7 History of wine making ............................................................................................. 12 2.8 Classification of wine ................................................................................................ 13 2.9 General cultural conditions for fermentation ............................................................. 15
2.9.1 pH ....................................................................................................................... 16 2.9.2 Temperature ........................................................................................................ 16 2.9.3 Sugar concentration ............................................................................................ 16
2.10 Wine yeast ............................................................................................................... 17 2.11 Alcoholic fermentation ............................................................................................ 17
2.11.1 Biochemistry of alcohol fermentation .............................................................. 18 2.11.2 Malo-lactic fermentation .................................................................................. 19
2.12 Technology of wine production ............................................................................... 19 2.12.1 Selection of raw material .................................................................................. 21 2.12.2 Blending/ Crushing ........................................................................................... 21 2.12.3 Sulphiting/ Preservatives .................................................................................. 21 2.12.4 Yeast ................................................................................................................. 21
2.12.4.1 Inoculum Development and Pitching ........................................................ 23 2.12.4.2 Fermentation .............................................................................................. 23 2.12.4.3 Factors influencing fermentation ............................................................... 25
2.12.4.3.1 Yeast culture ....................................................................................... 25 2.12.4.3.2 Sugar and its concentration ................................................................. 25 2.12.4.3.3 Sulphur-dioxide .................................................................................. 26 2.12.4.3.4 Acids and pH ...................................................................................... 26 2.12.4.3.5 Temperature ........................................................................................ 27 2.12.4.3.6 Minerals and growth factors ............................................................... 28 2.12.4.3.7 Oxygen ................................................................................................ 28
vii
2.12.4.3.8 Ethanol toxicity ................................................................................... 28 2.12.5 Problems during fermentation .......................................................................... 29
2.12.5.1 Stuck fermentation ..................................................................................... 29 2.12.5.2 Production of off-characters ...................................................................... 29 2.12.5.3 Methanol production and its quality .......................................................... 30 2.12.5.4 Activity of undesirable microorganisms .................................................... 30
2.13 Racking .................................................................................................................... 30 2.14 Clarification and fining ............................................................................................ 31 2.15 Stabilization of wine ................................................................................................ 31 2.16 Maturing and aging of wine ..................................................................................... 31 2.17 Bottling .................................................................................................................... 32 2.18 Pasteurization ........................................................................................................... 32 2.19 Finishing .................................................................................................................. 33 2.20 Storage and ageing of wine ..................................................................................... 33 2.21 Wine made from different raw materials ................................................................. 34 2.22 Fining agent and its types ........................................................................................ 35
2.22.1 The Proteins ...................................................................................................... 35 2.22.2 The Earths ......................................................................................................... 36
2.22.2.1 Bentonite and its properties ....................................................................... 36 2.22.2.2 Preparation of bentonite ............................................................................. 37
2.22.3 Synthetic Polymers ........................................................................................... 38 2.22.4 The Colloids ..................................................................................................... 38
2.22.4.1 Natural Polysaccharides ............................................................................ 38 2.22.5 Alternative Methods of Metal Depletion .......................................................... 39 2.22.6 Activated Carbon .............................................................................................. 39 2.22.7 Silica Suspension .............................................................................................. 39
2.23 Components of wine ................................................................................................ 40 2.23.1 Ethanol .............................................................................................................. 40 2.23.2 Methanol ........................................................................................................... 40 2.23.3 Higher alcohols (Fusel oils) .............................................................................. 41 2.23.4 Carbonyl compounds ........................................................................................ 41 2.23.5 Esters ................................................................................................................ 42 2.23.6 Acids ................................................................................................................. 42 2.23.7 Glycerol ............................................................................................................ 43 2.23.8 Minerals ............................................................................................................ 43 2.23.9 Pectins and gums .............................................................................................. 43 2.23.10 Water and sugar .............................................................................................. 44
2.24 Yield ........................................................................................................................ 44 2.25 Wine defects and spoilage ....................................................................................... 44 2.26 Wine and its health benefits ..................................................................................... 45 2.27 Brief Introduction of Ginger wine ........................................................................... 46
3. Materials and methods .................................................................................................. 47 3.1 Raw Materials ............................................................................................................ 47 3.2 Optimization of TSS and amount of ginger in the fermentation mash ...................... 47
3.2.1 Preparation of mash ............................................................................................ 47 3.2.2 Pitching and agitation ......................................................................................... 48 3.2.3 Fermentation ....................................................................................................... 48 3.2.4 Racking, pasteurization and bottling .................................................................. 48 3.2.5 Quality analysis .................................................................................................. 50
viii
3.3 Selection of the best yeast ......................................................................................... 50 3.4 Clarification of ginger wine using Bentonite ............................................................ 50 3.5 Analytical methods .................................................................................................... 50 3.6 Quality analysis of prepared wines ............................................................................ 51
3.6.1 Sensory evaluation .............................................................................................. 51 3.6.2 Statistical analysis ............................................................................................... 51
4. Results and discussion ................................................................................................... 52 4.1 Effect of TSS and ginger amount on the chemical and sensory quality of ginger wine ......................................................................................................................................... 52
4.1.1 Effect on chemical characteristics ...................................................................... 52 4.2 Effect of yeast culture on chemical and sensory properties ...................................... 57
4.2.1 pH ....................................................................................................................... 58 4.2.3 Alcohol content ................................................................................................... 58 4.2.4 Total acidity ........................................................................................................ 59 4.2.6 Volatile acidity ................................................................................................... 60 2.4.7 Reducing sugar ................................................................................................... 60 4.2.8 Esters .................................................................................................................. 61 4.2.9 Total aldehydes ................................................................................................... 61
4.3 Sensory Evaluation .................................................................................................... 61 4.3.1 Smell ................................................................................................................... 62 4.3.2 Taste .................................................................................................................... 62 4.3.3 Mouth feel ........................................................................................................... 62 4.3.4 Color ................................................................................................................... 63 4.3.5 Overall acceptance .............................................................................................. 63
4.4 Effect of bentonite on the clarification of ginger wine. ............................................. 63 5. Conclusion and recommendation ................................................................................. 65
5.1 Conclusions ............................................................................................................... 65 5.2 Recommendations ..................................................................................................... 65
6. Summary ........................................................................................................................ 66 References ........................................................................................................................... 68 Appendices .......................................................................................................................... 74
ix
List of fables and figures
List of tables Table2.1 The chemical composition of ginger……………………………………..…5
Table2.2 Classification of distilled and un-distilled alcoholic beverages produced from
different raw materials……………………………………….……………....9
a. Cereal Grains as raw materials……………………………....……………..9
b. Vegetables as raw materials……………………….…..…………....9
c. Fruit juice as raw materials……………………….….…………….10
d. Other Sources of raw materials…………...…………….................10
Table 2.3 Classification of wines………………………………………………….…...15
Table 2.4 Typical ranges of application of fining agents………………………………36
Table 3.1 Composition of different mashes…………………………..…………..…….47
Table 4.1 Chemical composition of the ginger wines……………...…………………..57
Table A.1 TSS reduction during fermentation of mashes………………………………73
Table A.2 Data obtained from analysis of samples of wines…………………………...73
Table A.3 Specimen cards for sensory evaluation by hedonic rating…………………..74
Table A.4 ANOVA table for chemical properties of ginger wines fermented by baker’s
yeast………………….…..……………………..……………………………75
Table A.5 ANOVA table for sensory characteristics of ginger wines fermented by
baker’s yeast……………….........…………..……………………………….76
Table A.6 Sensory evaluation scores of the wine samples…………................………...77
Table A.7 Chemical composition of the ginger wines fermented by true wine and baker’s
yeasts…………..…….………………………………………………………78
Table A.8 t-test table for chemical properties of the wines……....……………..………78
Table A.9 t-test table for sensory properties of the wines………………...…………….79
Table A.10 ANOVA table for turbidities of ginger wines………………...……………..79
Table A.11 Effect of bentonite on the clarification of ginger wine………..…..….……...80
Table A.12 Average chemical analysis of prize-winning high quality wines……….…...80
Table A.13 Major Wine producing countries of the world-1996………….………...…...81
Table A.14 Composition of some wines………….....……………….….……………….82
x
List of figures Figure 2.1 Simplified pathway of alcohol synthesis by yeast………….………………...18
Figure 2.2 The malo-lactic pathway……………………………………………………...22
Figure 3 Outline of Red Table Wine production……………………………………….22
Figure 3.1 Fermentation of ginger wine………………………………………………….48
Figure 3.2 Preparation of ginger wine……………………………………………………49
Figure 3.3 Clarification of ginger wine using bentonite………………………………….50
Figure 4.1 Effect of initial TSS on the TSS of the ginger wines …………………………52
Figure 4.2 Effect of ginger amount on the TSS of the ginger wines……………………...53
Figure 4.3 Effect of initial TSS on the alcohol content of the ginger wines……...………54
Figure 4.4 Effect of ginger % on the alcohol content of the ginger wines…………...…...54
Figure 4.5 Effect of initial TSS on the sensory properties………………………..………55
Figure 4.6 Effect of ginger amount on the sensory properties…………………..………..55
Figure 4.7 Effect of yeast type on the sensory properties of ginger wines fermented by true
wine and baker’s yeasts……………………………………………..…………61
Figure 4.8 Effect of bentonite on the clarification of ginger wine…………..…………….63
Part I
Introduction
1.1 General introduction
Alcoholic beverages are among the most popular and appreciated food products all over
the world (Ray et al., 2005). Large numbers of distilled and un-distilled alcoholic products
are enjoyed in different geographical regions throughout the world (Jones, 1985). Wine is
the end product of partial or complete alcoholic fermentation of the juice of grape (Prescott
and Dunn, 1987). It is also made from a variety of fruits, such as grapes, peaches, plums or
apricots etc. and saps of different palm tree (Okafor, 1972). Wine is an un-distilled
beverages having 6-20% ethanol by volume (Pearson, 1976). Wine represents a safe and
healthful beverage. It also provides calories and vitamins. Generally wine is made from
grapes. The grapes are crushed to squeeze out the juice and then are left for some time to
ferment (Amerine et al., 1972).
After this first step of winemaking, the primary fermentation stage that usually takes
around one to two weeks while yeast transforms majority of the sugars in the grape juice to
ethanol, which is alcohol. The resulting liquid is then transferred to several vessels for
secondary fermentation when the remaining sugar is slowly converted to alcohol and the
wine gets clearer in color. Some amount of the wine is then placed in oak barrels to age
before bottling that adds aromas to the wine.
Most of the wines, however, are placed inside bottles and shipped right away that can be
opened starting from after few months to twenty years for top wines. It is important to note
though that only a small percentage of wines will be tastier after five years, compared to
after one year. Wild yeast and other microorganisms are present on the skin of the grapes
and these pass into the juicy pulp (known as must) when the fruit is crushed. These are
destroyed by adding sulfur dioxide (or KMS) in the required quantity. Nowadays other
fruits are also used for winemaking. Many spices are used to flavor the wine (Manay and
Shadaksharaswamy, 1987).
Ginger wine is an alcoholic beverage made from a fermented blend of ground ginger
(Zingiber officinale Rosco.) and raisins fermenting by the yeast, Saccharomyces cerevisiae.
2
It is a popular beverage in Europe. The word drink is primarily a verb, meaning to ingest
liquids. Ginger is usually used to flavor a wine. It has many health benefits. Ginger wine
can be consumed by blending with whisky, brandy or rum.
The first documented appearance of Ginger wine occurred with the foundation of 'The
Finsbury Distilling Company' based in the City of London in 1740.
1.2 Statement of problem
Ginger is becoming the major cash crop for the mid-hill Nepalese farmers. Salyan, Palpa,
Tanahu, Syanja, Kaski, Nawalparasi, Bhojpur and Ilam are the leading districts for ginger
production. Most of the ginger is used as spices. The mother ginger root is harvested in
Ashad and Shrawan months. It is humid and heavy rainy season. So, most of the ginger is
decayed due to moist weather in a short period of time. There is no proper transportation
facility for marketing. There is no good market for the ginger. Nepalese farmers are not
getting a good profit by ginger production. It is very hard to achieve the returns of their
investment. So, if ginger is used for the production of ginger wine, farmers would get good
market for their ginger and their socio-economic status will be changed. Ginger has many
health benefits too. So, it would be a very valuable if we utilize ginger for making different
products such as wine, juice, candy, brandy that preserve for several months to years.
1.3 Significance of the study
My proposed work will be focused on the preparation of a good quality ginger wine by
using wine and baker’s yeasts. Ginger can also be used to prepare dry ginger candy. But it
is not an easy method. It requires a suitable dry weather and takes long time to prepare. It
can not be prepared in all seasons. Sugar is not easily available in the rural areas. Ginger
wine can be prepared easily by using baker’s yeast in rural areas which is as comparable to
the ginger wine made by using true wine yeast. It saves the ginger from decaying. If ginger
is used in winemaking, the people of Salyan, Palpa, Tanahu, Syanja, Kaski, Nawalparasi,
Bhojpur and Ilam will raise their economic status by the production of ginger wine and
brandy. Since ginger can be produced in large quantities in hill regions, we can utilize it
effectively for ginger wine production. Ginger wine is consumed in large quantity in
European and other countries. The ginger wine can be exported to those countries and
earned foreign currency. It helps to increase national income in our country.
3
1.4 Objective of the study
The overall objective of the study is to prepare a good quality ginger wine.
The specific objectives of the study are as follows:
I. To determine the optimum amount of ginger and sugar in fermentation mash for
winemaking.
II. Quality comparison of ginger wines prepared by true wine yeast and baker’s yeast.
III. Clarification of ginger wine by using bentonite.
IV. To determine the physicochemical properties of the ginger wine
V. To evaluate sensory characteristics of ginger wines fermented by true wine and
baker’s yeast.
1.5 Limitations
I. The suitable temperature could not be adjusted. Wine fermentation requires 15-
20oC for good quality wine. Ginger wine was prepared at higher temperature
(i.e.28-30oC) than desired temperature due to technical constraints.
II. Clarification could be done by other fining agents but only bentonite was used due
to time constraints.
III. The prepared ginger wine could not be aged properly due to time constraints.
Ageing is an essential requirement for the good organoleptic qualities of wine.
Part II
Literature review
2.1 Introduction of ginger
Ginger (Zingiber officinilae Rosc.) is an herbaceous perennial plant of the family
Zingiberaceae which consists of 47 genera. The genus Zingeber consists of 80-90 species
among them Officinale is cultivated one (Borget, M. 1989). Ginger is becoming the major
cash crop for the mid-hill Nepalese farmers. It is grown successfully from Terai (100
meters above sea level) to mid hills (1500 meters above sea level).
Ginger is one of the oldest spices to be supposedly native to South East Asia, but like
many other tropical plant of economic importance, its exact origin is uncertain. It is
mentioned in early literature of China and India. The adventurer, Marco Polo, in recording
to his travels during the 13th and 14th centuries, noted that ginger was being cultivated in
South China and Malabar Coast of India (Leverington, 1983).
2.2 Varieties of ginger cultivated in Nepal
Ginger is one of the important spices as well medicinal plants in the country. It is
becoming the major cash crop of the mid-hill farmers of Nepal. Salyan, Palpa, Tanahu,
Syanja, Kaski, Nawalparasi, Bhojpur and Ilam are the leading districts for ginger
production.
As ginger rarely set seeds, the general mode of propagation is asexual. This leads to little
variation between forms grown over a wide geographical area (Lawrence, 1984). Therefore
the classification of cultivars of ginger is done according to their germplasm collected area,
such as Calicut, Cochin, Reo de Generio, Salyan, Ilam etc.
In Nepal, locally available ginger has two varieties- fibrous (NASE) and non fibrous
(BOSE). The germplasm collected from Salyan, Bhojpur and Ilam fall under the ‘BOSE’
variety and these are considered the best in quality (Sharma, 1997).
5
2.3 Composition of ginger
The ginger rhizome contains a mixture of an essential oil, a fixed oil, pungent compounds,
starch and other saccharides, proteins, cellulose, waxes, coloring matter, trace minerals etc.
Starch is the most abundant of these components (Jogi et al., 1972). Chemical composition
of ginger varies with varieties, climatic condition, soil condition, fertilizer used etc. Further
there is a great effect of maturity, handling, storage, drying and other processing methods
on the chemical composition of ginger. The chemical composition of green ginger is given
in table 2.1.
Table 2.1 The chemical composition of ginger
Component Value Watt and Merril, 1975 Value Swaminathan, 1974
Moisture (g) 80.89 87
Protein (g) 2.3 1.4
Fat (g) 0.9 1
Fibre (g) 2.4 1.1
Carbohydrate (g 12.3 9.5
Calcium (g) 0.02 0.023
Phosphorus (g) 0.06 0.036
Iron (g) 2.6 2.1
Carotene (mg) 40 40
Thiamine (mg) 0.06 0.02
Niacin (mg) 0.6 0.7
Riboflavin (mg) 0.03 0.04
Ascorbic acid (mg) 6 4
2.4 Ginger and its health benefits
Ginger has been revered for its medicinal and culinary benefits for centuries. The
underground stem known as the rhizome contains the most medicinal benefits of the plant.
The volatile oils of the ginger plant gives ginger its characteristic odor and taste. It is best
to use ginger in its fresh form to obtain the most health benefits from its use. Ginger has
the following health benefits:
6
1. Ginger can help to alleviate diarrhea, aid digestion and reduce flatulence. It also helps
to relieve the nausea associated with morning sickness and motion sickness. Ginger
also helps to neutralize stomach acid that can cause upset and diarrhea.
2. Ginger has natural anti-inflammatory properties. It helps to reduce the inflammation
associated with arthritis.
3. Ginger is a natural decongestant and antihistamine. It helps to relieve the congestion of
colds, and reduces fever as well.
4. Ginger may help to prevent the formation of blood clots by relaxing the muscles around
blood vessels. Ginger is also a natural blood thinner.
5. Ginger can help to lower cholesterol and prevent blood platelets from clumping
together. It also stimulates the circulatory system.
6. Ginger may also be beneficial in the prevention of heart disease and cancer, as well as
in the treatment of diabetes. Research continues to determine the effectiveness of
ginger in these areas as well as other health conditions.
(Source: http://www.ehow.com/facts_4924826_health-benefits-ginger.html)
2.5 Historical background of alcoholic beverage
Alcoholic beverages are among most popular and most appreciated food products all over
the world. Alcohol was discovered in 8327 B.C. on a warm afternoon by “Grog” who
returned to his cave and drank the fermented milk of a coconut that had been cracked and
left out in the sun. Beer and berry wines were made for the first time in 6400 B.C. while
Grape wines were made in 300-400 B.C. (Ray et al., 2005). Large numbers of distilled and
un-distilled alcoholic products are enjoyed in different geographical regions throughout the
globe. Alcoholic beverages are believed to have originated in Egypt and Mesopotamia
some 6000 years ago (Jones, 1985).
Despite this early application of microbiology, the ability of microorganisms to stimulate
the biochemical changes was demonstrated several years later. Gay Lussac first identified
alcoholic fermentation in 1810, but at that time yeast was not recognized as a causative
organism. Schwan in 1835 demonstrated that yeast could produce alcohol and carbon
dioxide when introduced in sugar-containing solution. He termed yeast Zuckerpilz meaning
sugar fungus from which the name Saccharomyces originated (Prescott and Dunn, 1987).
Saccharomyces group possesses almost all the credits of producing alcoholic beverages
(Tannanhill, 1937).
7
The production and consumption of alcoholic beverage is one of the man’s oldest
activities. Today brewing, wine making and distilling are of major commercial importance
in many non-Islamic countries and, through taxation, can be an important source of
government revenue (Vernam and Sutherland, 1994).
There are different types of alcohols. Some are used in chemistry and industry, e.g.
isopropyl and methyl alcohol. Another type of alcohol, also known as ethanol has been
consumed by human beings for its intoxicating and mind-altering effects. The term
‘alcohol’, unless specified otherwise, refers to ethanol or ethyl alcohol.
2.5.1 Brief description of alcoholic beverages
There are many types of alcoholic beverages. They are briefly described as;
Wine: Wines are the oldest of the alcoholic beverages made by fermentation of grape
juice. Wine, strictly speaking, is a product of vine, but often includes all fermented liquors
obtained from different fruit juices (fruit wines). Wines differ greatly in their characters,
because grapes grown in different regions differ in composition, particularly in their
volatile components which contribute to flavor and bouquet and in the method used for
wine making (Amerine et al., 1972).
Wine is the end product of partial or complete alcoholic fermentation of the juice of
grape (Prescott and Dunn, 1987). It is also made from a variety of fruits, such as grapes,
peaches, plums or apricots etc. and saps of different palm tree (Okafor, 1072).
Wine is an un-distilled beverages having 6-20% ethanol by volume (Pearson, 1976).
Most of the natural wines contain 8-10% alcohol. Fortified wines contain about 20%
alcohol, which is sufficiently high to kill the microorganisms that attack natural wines.
Wines containing less than 14% alcohol are table wines, whereas those containing more are
dessert wines. The term wine is broadly used to include any properly fermented juice of
ripe fruits. The names of the fermented products are different according to the types of
fruits used. For example: the product obtained from the grape juice is known as wine,
similarly product from apple juice and pear pulps are known as cider and perry respectively
(CFRL, 1984).
The most common wines are produced from grapes. The soil in which the grapes are
grown and the weather conditions in the growing season determine the quality and taste of
the grapes which in turn affects the taste and quality of wines. When ripe, the grapes are
crushed and fermented in large vats to produce wine.
8
Beer: Beer is also made by the process of fermentation. A liquid mix, called wort, is
prepared by combining yeast and malted cereal, such as corn, rye, wheat or barley.
Fermentation of the liquid mix produces alcohol and carbon dioxide. The process of
fermentation is stopped before it is completed to limit the alcohol content. The product so
produced is called beer. It contains 4 to 8 percent of alcohol.
Whisky: Whisky is made by distilling the fermented juice of cereal grains such as corn, rye
or barley. Scotch whisky was originally made in Scotland. The word “Scotch” has become
almost synonymous with whisky of good quality.
Rum: Rum is distilled beverage made from fermented molasses or sugarcane juice and is
aged for at least three years. Caramel is sometimes used for coloring.
Brandy: Brandy is distilled from fermented fruits juices. Brandy is usually aged in oak
casks. The color of brandy comes either from the casks or from caramel that is added.
Gin: Gin is a distilled beverage. It is a combination of alcohol, water and various flavors.
Gin does not improve with age, so it is not stored in wooden casks.
Liqueurs: Liqueurs are made by distilling sugar and flavoring such as fruits, herbs or
flowers to brandy or to a combination of alcohol and water. Most liqueurs contain 20-65
percent alcohol. They are usually consumed in small quantities after dinner.
2.5.2 Classification of alcoholic beverages
There are different types of distilled and un-distilled congeneric alcoholic beverages all
over the world according to source of raw materials; some are listed in the following table
2.2.
9
Table 2.2 Classification of distilled and un-distilled alcoholic beverages produced from
different raw materials.
a. Cereal Grains as raw materials.
Source Name of fermented beverage Name of distilled beverages
Barley Beer, Barley wine Scotch whisky, Irish whiskey
Rye Rye beer kvass Rye whiskey, Roggenkon (Germany)
Corn Chichi, Corn beer Bourbon whiskey, Vodka
Sorghum Burukutu (Nigeria), Pito
(Ghana)
Maotai, Gaoliang, types of Baijiu
(China)
Wheat Wheat beer Wheat whisky
Rice Huangjiu, Choujiu (China), Sake,
Sonti, Makkoli,
Rice baijiu (China), Shochu and
Awamori (Japan)
Millet Millet beer(Sub-Saharan Africa),
Tongba (Tibet)
b. Vegetables as raw materials.
Source
Name of
fermented
beverage
Name of distilled beverage
Juice of ginger
root
Ginger beer
(Botswana)
Potato and/ or
Grain
Potato beer Vodka: Poland and Germany, Aquavit or Brannvin:
Sweden, Akvavit: Denmark
Beets Pink vodka/ Woman’s vodka/ Girlie vodka (Russia)
10
c. Fruit juice as raw materials.
d. Other Sources of raw materials.
Source Name of fermented beverage Name of distilled beverage
Sap of
palm
Coyol wine (Central America), Tembo
(Sub-Saharan Africa), Toddy in
Nigeria, Tadi (Nepal)
Arrack
Honey Mead, Teg (Ethiopia) Distilled mead (“mead brandy” or
“honey brandy”)
Pomace Pomace Wine Raki (Turkey), tsikoudia (Greece),
grappa (Italy), Trester (Germany),
marc (France)
Milk Kumis or Kefir Araka
Source: htto://en.wikipedia.org/wiki/Alcoholic_beverage
Source Name of fermented
beverage Name of distilled beverage
Juice of grapes Wine, grapes wine Brandy, Cognac (France)
Juice of apples (“Hard”) Cider,
Apfelwein
Applejack (or apple brandy), Calvados,
Cider, Lambic
Juice of pears Perry, or Pear cider,
Poire (France)
Pear brandy, Eau-de-Vie (France)
Juice of sugarcane,
or molasses
Basi, Betsa- betas
(regional)
Rum (Caribbean), Pinga or Cachaca
(Brasil), Aguardiente, Tequila, Mezcal
Juice of agave Pulque Tequila, Mezcal
Juice of plums Plum wine Slivovitz, Tzuica, Palinca
Juice of pineapples Tepache (Mexico)
Juice of Bananas Urgwagwa (Uganda,
Rwanda)
11
2.6 Traditional alcoholic beverages of Nepal
Alcoholic beverages have played an important role in human spiritual and cultural life both
in Eastern and Western societies. Unlike in Europe and the Middle East, where indigenous
alcoholic beverages are produced primarily from fruit, alcoholic beverages are produced
from cereals in the Asia-Pacific region, and serve as an important source of nutrients.
European beer uses barley malt as the primary raw material, while Asian beer utilizes rice
with molded starters as the raw material. Beverages vary from crystal-clear products to
turbid thick gruels and pastes. Clear products which are generally referred to as
Shaosingjiu in China, Chongju in Korea and Sake in Japan, contain at least 15% alcohol
and are designated as rice-wine, while turbid beverages, such as Takju in Korea and Tapuy
in the Philippines which contain less contain less than 8% alcohol along with suspended
insoluble solids and live yeasts, are referred to as rice-beer (Haaed, 1999).
2.6.1 Jand
Jand is an alcoholic beverage (un-distilled) indigenous to Nepal. It is prepared by solid-
substrate fermentation of starchy cereals like corn, rice, wheat and millet. Murcha, a starter
culture, is used as the inoculum in traditional fermentation. Murcha contains saccharifying
molds, lactic acid bacteria and fermenting yeasts. Jand is therefore the result of concerted
action of these microorganisms on the cooked cereal (Rai, 2005).
2.6.2 Rakshi
Raksi (also spelt rakshi, rukhsi) is an un-aged congeneric spirit obtained by pot distillation
of the slurry of jand. The product likens whiskey and has highly varying alcohol contents
(K.C. et al., 2004), generally between of 15 and 40% (Subba et al., 2005). Several basic
researches have been done on raksi production from different cereals using murcha starter
as well as wine cultures isolated thereof (Rai, 1984) but there seems to be general lack of
attention towards process development such as preparation of good starter culture,
increasing efficiency of traditional distillation apparatus, and separation of fients and
foreshots for improving quality of raksi.
2.6.3 Toddy/ Tadi
It is a fermented sap of palm trees by natural contamination. In Nepal naturally fermented
palm sap used as alcoholic beverage is called “Tadi”. Traditionally, sap is collected
12
overnight in clay pots (with bottom containing a crust of microorganisms formed from the
previous fermentation), from the slit made at the top portion of the tree trunk. The tapped
sap, which is trickles down into the collection pot, is inoculated and fermentation sets
immediately. The sap is converted into sweet Tadi by the fermentation. This product is
white and effervescent (Dhakal, 2007).
2.7 History of wine making
As stated by sir John Malcohn in his first account of Persia during the regime of king
Jamshed, Viticulture flourished and it is he who is credited with the dictionary of
fermentation (Andrew, 1980). History of wines has left its traces in Near East, particularly
Mesopotamia (Iraq, Iran territory), later– in Persia (Iran), Egypt, Ancient Greece, Roman
Empire. Think of Greek classical pottery and Dionysus cavorting with his satyrs and
maenads and you will get a clue of the ancient history of wine that created immortal
legends. Egyptian history of wines origin in Nile delta– the fertile land where grapes grew
and white wine made from what is today called the Muscat grape of Alexandria. It is not
surprising that the early Egyptians attributed this drink with the god Osiris and used it
during funerary rituals.
Since Roman times, wine (potentially mixed with herbs and minerals) was assumed to
serve medicinal purposes as well. It was not uncommon to dissolve pearls in wine for
better health. Cleopatra created her own legend by promising Marc Anthony she would
"drink the value of a province" in one cup of wine, after which she drank an expensive
pearl with a cup of wine. From Rome winemaking greatly prospered under the Catholic
Church who held widespread influence over Christian Europe. Eventually, winemaking
capability and practiced extended to far-flung places like England who enjoyed wine
varieties of Sherry, Port and Madeira. Christian monks of France and Northern Italy kept
records of their winemaking practices and grape cultivation. By 1800, France would be
recognized as the best of the wine-producing regions of the world.
(Source: http.//www.metalimagination.com/winemaking.html).
The Pheonicians from Lebanon introduced the wine and its secrets to the Romans and
Greeks who subsequently propagated wine making and even dedicated a God to wine the
Roman Bacchus and the Greek Dionysus. Fermented beverages have been produced since
the Paleolithic period probably at first by accident from honey. Later, cereals were used
13
and then grapes and various fruits. During the Neolithic period, wines from fruits, and
especially from grapes, were more popular in Greek and Roman territory (Dhakal, 1988).
Heating wine to produce a caramelized or baked odor was known in the Roman period. In
the 19th century, it was first used in the Madeira Islands (Johnson, 1974).
Crude methods of clarification, preventing spoilage, and treating spoiled wines were
developed by the Romans (Kirk, 1969). Wine is probably the most widespread and
historically significant beverage starting from ancient times. Wine is the drink of kings,
just as it is the beverage of choice for ordinary people. Wine has played a major role in the
rise and fall of countless individuals, nations and even civilizations. History of wine is very
long, interesting and intricate at the same time; nevertheless, classification of wine is no
less capturing and complicated as its history.
Grape wine is found widely distributed throughout the world. The most important species
Vitis vinifera is believed to have been brought by man from Southern Russia to Asia
Minor. Europe is obviously the most important wine-producing area with more than 75%
on average and over 68% of wine production comes from European countries, with France
and Italy capturing nearly 45% of total production (Amerine et al., 1967). For the mass
production in wineries, new methodologies and technologies were implemented so called
modern wineries. (Source: http://www. Byronwines.com/iw_facilities.asp)
Modern wineries are automatic and computerized and are capable of producing 3-4
million liters of wine with only handful of people (Birch and Lindley, 1985). More
recently, the use of tower fermentation (Berry and Watson, 1987) with timer and
programmer for the production of both wine and cider has been demonstrated.
In Nepal, there are only three wineries, one in Basantapur, Tehrathum (Makalu wine
industries (P.) Ltd.) and others in Jomsom, Mustang and Pokhara (Hill Hut Winery) to
produce raspberry wine, cider and different fruit wines respectively.
2.8 Classification of wine
Types of wines are normally classified by vinification method, by taste, by vintage, by
wine style, and/or by quality. Vinification refers to how the wine is made. Vinification
wine classification refers to three major categories: table wines, sparkling wines, and
fortified wines. Types of wine can also be classified by taste. Table wines, for instance, are
classified by character as dry (not sweet), semidry, semisweet; sweet wines are classified
as dessert wines. Apart from palate, types of wines can also be distinguished by sugar and
14
alcohol percentage. Dry wine contains 2-3% of sugar and about 10% of alcohol– such wine
is the lightest. Semisweet wines have sugar 5-6% and alcohol 13-14%, while semidry
wines are a little bit sweeter than semisweet ones. Dessert or sweet wines contain the
highest percentage of sugar and alcohols than other types of wine– about 14-16%, and 16%
of alcohol. Table wines are also further classified by color, as red, white, or rose (pink). In
addition to this wine classification, wines may also be classified according to specific
flavors, types of grape they are made of and origins where this grape grew.
Table wines, also called still or natural wines, are consumed mostly with food, they tend
to compliment the meal. Table wines contain less than 14% alcohol. White dry wine is
usually served with seafood, fish, cheese, or nuts. Red dry wine is served with meals of
meat and vegetables that are roasted, stewed, smoked, etc. Fortified or dessert types of
wine, such as sherry or vermouth, are most commonly drunk before or after meals and are
served with various cakes, pastry, chocolate, fruits, etc. Fortified wines are also frequently
used in cooking. Concerning sparkling wines, for example champagne, is distinguishable
by its effervescence and is drunk for the most part on festive occasions such as weddings,
birthdays, and during the holidays.
Wines are usually named either by their grape variety or by their place of production.
Generally speaking, European wines are named both after the place of production (e.g.
Bordeaux, Rioja, Chianti, Cotnari) and the grapes used (e.g. Pinot, Riesling, Chardonnay,
Merlot). Wines from everywhere except Europe are generally named for the grape variety.
Whether you prefer vintage wine or not, whatever the classification of wine you like, wine
is an ideal gift for any special occasion.
Wines can be classified on various bases viz., (i) color, (ii) relative sweetness, (iii)
effervescence, (iv) alcohol content, and (v) the system used by Wine Advisory Board,
USA. However, the basic groups of wines are most easily distinguishable for the consumer.
They are (i) table wines, (ii) sparkling wines, and (iii) fortified wines. A summary of the
classification scheme is given in table 2.3.
15
Table 2.3 Classification of wines.
Basis of classification Class/ type Description Example
Color Red wine Contains the red coloring matter of skin,
pulp and seeds.
Burgundy
White wine Does not contain the red coloring matter,
pulp and seeds.
Rhine wine
Pink wine Low concentration of red coloring
matter is maintained.
Rose
Relative sweetness Sweet wine Contains up to 7% sugar. Sherry
(sweet)
Dry wine Contains less than 0.12% sugar. Sherry (Dry)
Alcohol content Natural Contains 8.5-16% alcohol by volume (%
abv)
Table wines
Fortified Contains 17-21% abv. Sherry
Effervescence Still Does not contain CO2 Chianti
Sparkling Contains CO2 (Natural or Artificial ) Champagne
Wine Advisory Board,
USA
Dessert wine Contains sugar; taken after meal Sherry
(Sweet)
Appetizer
wine
Dry; fortified; taken before meal Sherry (Dry)
Sparkling
wine
Contains CO2 Champagne
Red-table
wine
Natural; red in color Chianti
White-table
wine
Natural; pale yellow to straw color Rhine wine
Note: There is considerable overlapping of wine types in the classification shown above.
For example, a Red Table wine can at the same time is sweet, sparkling, fortified, or
natural. Similarly, a fortified wine can be sweet, sparkling, red, or white (Rai, 2002).
2.9 General cultural conditions for fermentation
Cultural condition refers to the environment of yeast i.e. fermentation media on which the
propagation of yeast as well as final quality of wine is largely depended (Varnam and
16
Sutherland, 1994). Following are the few parameters, which determine cultural condition
of the fermentation media.
2.9.1 pH
The optimum pH for wine production varies from types of the selected fruit but generally
3.8-4.5 is supposed to be optimum. At higher pH, the concentration of glycerine is
increased during fermentation whereas at lower pH, there is a noticeable effect of log phase
(Prescott and Dunn, 1987).
2.9.2 Temperature
The optimum temperature for the fermentation is dependent upon the types of wines
produced. For white wine, the temperature is 10-15oC and that for the red wine is 20-30oC
(Prescott and Dunn, 1987). There is possibility of ‘stuck’ fermentation if it is carried at
higher temperature. On the other hand, low temperature may delay onset of fermentation.
At high temperature, the loss of alcohol and aroma substance takes place. Also, a large
amount of by-product like glycerol, acetaldehyde may be formed. An imbalance of these
constituents can be very detrimental to wine quality. It has been reported that at higher
temperature the formation of higher alcohol decreases (Peynand and Gumiberteau, 1962).
The fermentation temperature for most white wines is in the range of 18oC to 24oC and
there is little interest in fermenting at higher temperatures due to the progressive loss of
volatiles under these conditions. The contribution of the fermentation temperature to white
wine aroma is directly related to the retention of grape-based aromas and formation of the
group of volatile byproducts referred to as fermentation bouquet (Boulton et al., 1997).
There are additional effects of fermentation temperature on the formation of glycerol
(Ough and Amerine, 1965) and the higher alcohols (Ough et al., 1966). The advantage of
lower fermentation temperature are the fresher and fruitier character of wine, smaller losses
of ethanol and less danger of producing volatile acidity (Prescott and Dunn, 1987).
2.9.3 Sugar concentration
The ‘must’ having very high sugar concentration imparts high osmotic pressure, which in
turn has a negative effect on yeast cells, since both growth of yeast and fermentation
activity are lowered. The tolerance of higher sugar concentration varies according to the
yeast species (Prescott and Dunn, 1987).
17
2.10 Wine yeast
Wine yeast is the member of the Saccharomyces cerevisiae group. The name originates
from the Greek word sakchar means sugar and mykes means fungus, referring to the strong
sugar fermenting properties of the genus in general. Although, Hansen regarded them as a
separate species, they are more ellipsoid in shape than the round or oval cells of brewery
and bakery yeasts. Hansen restricted the name S. ellipsoideus to them. In the nomenclature
of Dutch school, these yeasts are classified as a variety of S. ellipsoideus and consequently
named S. cerevisiae var. ellipsoideus (Austin, 1968).
Good wine yeast is one which will impart a vinous or fruit like flavor, will ferment sugar
to a low content producing 14-18% alcohol, and is characterized by remaining in
suspension during fermentation and than agglomerating to yield a coarse granular sediment
that settles quickly and is not easily disturbed in racking (Pederson, 1971).
Good wine yeast should have the following four properties:
1. High alcohol tolerance, i.e. the yeast should continue to ferment despite the
increasing concentration of the alcohol, giving stronger, drier wines with up to 16%
alcohol (v/v), or even up to 18% (v/v) where the yeast is fed by periodic additions
of sugar in small amounts.
2. Good degree of agglutination, i.e., the tendency of the yeast to flocculate into small
lumps that give a cohesive sediment as fermentation ceases, so that racking is
simple and the wine clears easily.
3. Steady, persistent fermentation capacity; this leads to wines of better quality than
when the fermentation falls away after a tempestuous start.
4. Absence of unpleasant flavors generated by dead and dying cells (Austin, 1968).
2.11 Alcoholic fermentation
There are different kinds of alcohols, but when the term is used loosely as by winemakers,
it invariably applies to the potable alcohol called ethyl alcohol or ethanol. It mixes easily
with water in any proportion and where quantities are mixed there is a contraction in
volume. It has a low boiling point, 78.4oC, compared with water. It burns easily in air, so
that oxidation is possible and then gives a blue, smokeless flame, producing water and
CO2. Ethyl alcohol is produced by the zymase complex of enzymes in yeast (Austin,
1968). There are three main classes of alcoholic beverages; wines, malted beverages and
18
distilled liquors (Lal et al., 1987). The essential step in all the fermentation processes is the
conversion of glucose into alcohol by yeast (Manay and Shsdasharaswamy, 1987).
The intermediate products are methyl glyoxal (CH3:OCH:O), Acetaldehyde (CH3CHO)
and pyruvic acid (CH3COCOOH).
Alcoholic fermentation is simply the production of alcohol by using carbon and nitrogen
substrate (Kaushik and Yadav, 1997). Sugar and nitrogen compounds are the principal
substrates for alcohol fermentation (Prescott and Dunn, 1987).
2.11.1 Biochemistry of alcohol fermentation
Alcoholic fermentation is an anaerobic process (i.e. takes place in the absence of air).
Microorganisms utilize the carbohydrate present in the materials to obtain energy for
growth and metabolic activities, leading to the formation of alcohol. Monosaccharides
(hexoses) are directly fermented. The flow of carbon in ethyl alcohol formation takes place
via the well known Embden-Meyerhof-Parnas pathway (Patel, 1999). The formation of
alcohol from sugar is accomplished by yeast enzymes which are contributed by the
growing yeasts. S. ellipsoideus is the true wine yeast. The organism uses EMP pathway,
generating two ATPs per mole of glucose converted to ethanol, plus CO2. Ethanol, which
is the end product, is primary metabolite. In an industrial fermentation, the basic strategy is
to maintain Crabtree effect during the fermentation. A truncated form of the metabolic
pathway for ethanol synthesis is given in Fig. 2.1.
Fig. 2.1 Simplified pathway of alcohol synthesis by yeast.
+C6H12O6 C2H5OH 2CO2
2ADP2ATP
Glucose 2[1, 3-di P glycerate]
4 ADP
4 ATP
4 Pyruvate
2 Acetaldehyde
2 [NAD + H+] 2 [NAD]
Alcohol dehydrogenase2 Ethanol CO2
19
2.11.2 Malo-lactic fermentation
It refers to secondary fermentation in which lactic acid bacteria are allowed to metabolize
malic acid to lactic acid and carbon dioxide. This fermentation is particularly useful if the
titrable acidity of wine is to be reduced. Wines with low levels of acidity should be
protected from malo-lactic fermentation: wine quality decreases if the acid level falls too
low. Malo-lactic fermentation can be easily prevented by early racking, cool storage, and
maintaining 100 p.p.m. or more of SO2. On the other hand, if such fermentation is desired,
it can be facilitated by leaving the wine on the lees (yeast sediments) for prolonged periods
at higher temperatures. This storage causes lysis of yeast cells and releases amino acids and
other nutrients needed for the growth of the ‘contaminant’ lactic acid bacteria.
Malo-lactic fermentation has an important bearing in the quality of wine. It is a natural
way of reducing acidity in wine. Besides, the fermentation also results in wines with
greater softness and mellowness. The bacteria implicated for malo-lactic fermentation are
Leuconostoc oenos, Lactobacillus, and Pediococcus, the first one being the most important
(Rai, 2005). The biochemistry of fermentation is given in figure 2.2.
Figure 2.2 The malo-lactic pathway.
2.12 Technology of wine production
Winemaking starts during the time of harvest when grapes are selected and placed in
containers. After harvesting, the grapes are crushed to squeeze out the juice and then are
left for some time to ferment. The winemaking technology of red and white wines also
differs. If red wine is desired, the skins are left to soak in the juice for a while so that the
wine would take the skin’s color. In order to make white wine, the juice is extracted with
COOH
COOH
CH2
COOH L-malic acid
L-malate dehydrogenase Pyruvate + CO2
Malo-lactic enzyme
L-lactose dehydrogenase
CH3CH2COOH
20
minimal contact from the grape skin. After this first step of winemaking, the primary
fermentation stage that usually takes around one to two weeks while yeast transforms
majority of the sugars in the grape juice to ethanol, which is alcohol.
According to winemaking technology, the resulting liquid is then transferred to several
vessels for secondary fermentation when the remaining sugar is slowly converted to
alcohol and the wine gets clearer in color. Sweet wines are created by allowing some
residual sugar to remain before or after fermentation or by adding another alcoholic
beverage to kill the yeast before fermentation is completed. Some amount of the wine is
then placed in oak barrels to age before bottling that adds aromas to the wine. Most of the
wines, however, are placed inside bottles and shipped right away that can be opened
starting from after a few months to twenty years for top wines. It is important to note
though that only a small percentage of wines will be tastier after five years, compared to
after one year.
Wild yeast and other microorganisms are present on the skin of the grapes and these pass
into the juicy pulp (known as must) when the fruit is crushed. These are destroyed by
adding sulfur dioxide (or KMS) in the required quantity. If the sugar content is low,
sucrose is added to the desired strength and the pH is adjusted to 3.2 to 3.4 by the addition
of tartaric acid. Next, the must is inoculated with a wine culture of actively growing yeast
(S. ellipsoideus). The temperature and duration of fermentation depend upon whether dry
or sweet wine is required. Fermentation usually lasts 4-10 days.
When fermentation is complete, the clear wine is siphoned from the yeast sediment into
barrels (racking) and the wine is allowed to age. During this period, secondary
fermentation takes place and wine also losses its raw and harsh flavor and mellows down.
During this period of maturation, clarification takes place in natural way. It can also be
achieved by fining and filtration. Next, the wine is bottled and allowed to mature; the time
of this maturation extends to a number of years depending upon the quality desired (Manay
and Shadaksharaswamy, 1987).
21
2.12.1 Selection of raw material
A suitable raw material is chosen to function as a substrate. Compared to cereals, fruit
juices are more readily utilizable substrate by yeasts for the alcoholic fermentation. The
later is also a suitable media for the yeast to grow (Varnam and Sutherland, 1994). Good
raw material for fermentation should be clean, sound, mature, impart from any taste and
odor and good source of carbon and Nitrogen with sufficient amount of fermentable sugar.
(Source: http/www.austwine/0089a/rm.html).
2.12.2 Blending/ Crushing
This step is carried out to extract the juice from the fruit. It has been suggested that the
process should be very gentle (Vernam and Suthearland, 1994). If the blending and
crushing machine is constructed of mild steel or cast iron then iron causes ‘ferric casse-
cloudiness’ of wine due to iron; actually iron will react with the tannin of the juice to form
ferric-tannin complex. Bronze equipment is also used but may cause dissolution of copper
and tin from bronze equipment and it will affect the color. Usually, stainless steel is used
for the crushing machine. Water may be added during blending/crushing for smoothness of
operation.
2.12.3 Sulphiting/ Preservatives
The antiseptic and antioxidant properties of sulfur dioxide are taken advantage of both in
connection with treatment of musts prior to fermentation and later in the winemaking
process. The dosage of SO2 usually ranges between 100 and 200 p.p.m. (Douglas and
Considine, 1982). SO2 is added before the fermentation process to prevent air oxidizing the
juice and converting the alcohol into vinegar. The air has bacteria principally Acetobacter
i.e. it is alive in the presence of air of oxygen, takes of the oxygen from the must to let the
wine yeast which is anaerobic condition convert the fruit sugar into alcohol. SO2 also
forms a coating on the surface of juice to prevent the air entering the juice (Andrew, 1980).
2.12.4 Yeast
Wine yeasts are the member of Saccharomyces and consequently of great individual
importance (Austin, 1968). A good quality of wine yeast should have the following
characters (Vernam and Sutherland, 1994):
• Introduction of flocculation and reduction of H2S production.
22
• Reduction of higher alcohol production.
• Improvement of fermentation efficiency.
• Resistance of ethanol.
• Resistance of killer activity.
Fig. 2.3 Outline of Red Table Wine production
Red table wine
Bottling, Labelling, Casing
Secondary Fermentation and Filling
Racking, Blending, Fining, Malo-lactic fermentation
Filtration and Tartarate Stabilization
Polishing
Pasteurization
SO2 (75 ppm)
Yeast
Press wine
Propagation
Free-run wine
Primary Fermentation
Drawing off and Pressing
Purple grapes
Destemming
Crushing
Must
Must Treatment
Pomace
SO2 (75-125 ppm)
23
2.12.4.1 Inoculum Development and Pitching
Sufficient quantity of inoculums (pitch) is developed before the preparation of must. The
developing medium should have law sugar concentration so that the ‘Pasteur Effect’ is
maintained and maximum growth is necessary for the respiration of growing yeast cells.
The medium should, preferably, be the juice of the same fruit so that the yeast is adopted
with the fruit juice composition. Pitching is done when the culture of the pitch is at its
optimum stage of growth. Vigorous agitation is done after pitching to help distribute the
culture and also to help in their initial growth (Karki, 2001).
2.12.4.2 Fermentation
In alcoholic fermentation by yeast, which is an anaerobic process, sugar (or glucose) is the
substrate and alcohol is produced as the product along with carbon dioxide. According to
the Gay-Lussac’s equation, theoretical yield of 51.1% alcohol (ethanol) and 48.9% CO2 of
the weight of the sugar fermented, is possible. This is biologically unobtainable and
possible only in absence of yeast growth and loss of alcohol as vapor (Karki, 2001). The
yield of alcohol varies from 47.87 to 48.12% and of CO2 from 47.02 to 47.68% of the
weight of sugar fermented (Gvaladez, 1936). Fermentation is the soul (heart) of wine
making. All the desirable reactions take place during this step, so most of wine makers pay
strict attention to this stage. Fermentation is the process of adding wine yeast (technically
termed as S. ellipsoidues) to fresh juice to convert the natural sugar to ethyl alcohol. In this
process, CO2 is simultaneously released making fermentation violent at first and then slow.
The yeast added is 1-3% of the volume of the juice. Generally, 14 days is required for
complete alcoholic fermentation.
Most of the fermentation takes place in three stages.
• An initial stage during which time the yeast cells are multiplying.
• A very vigorous stage accompanied by bubbling and marked rise in temperature.
• Quiet fermentation that can proceed for quite along time at a lower and lower rate.
Fermentation time may range from 2-20 days depending upon numerous variables- types
and condition of fruits, type of wine made, and climatic conditions. Among others
temperature is quite critical to the fermentation process (Douglas and Considine, 1982).
The optimum temperature for fermentation of red wine is higher than that of white wine.
The optimum temperature is believed to be 21.1-27.4oC (Johnson and Peterson, 1974). At
temperature above 90oF (32.2oC), it is likely that wine flavor and bouquet will be injured.
24
High temperature also encourages heat tolerant bacteria to produce acid, mannitol and off
flavor (Douglas and Considine, 1982).
At the usual total sugar content of 19-23%, alcoholic fermentation proceeds rapidly and,
with alcohol tolerant strains of yeast, to completion, producing about 10-12.5% alcohol (by
volume) (Johnson and Peterson, 1974). If sugar content is greater than 23%, the high sugar
content may inhibit fermentation and the rate of fermentation, form glycine for example,
but is primarily derived from hydrolysis of naturally occurring pectin. The amount of
higher alcohols produced is less when ammonium phosphate is added prior to
fermentation. At very low concentration, the higher alcohols may play a desirable role in
sensory quality (Amerine et al., 1967). The oxidative conditions during fermentation favor
higher alcohol production (Guymon et al., 1961). Glycerol production is favored by low
temperature, high tartaric content and by addition of SO2. Most of the glycerol develops in
the early stages of fermentation. Most enologists consider that glycerol is of considerable
sensory importance because of its sweet taste and its oiliness (Gentillini and Cappelleri,
1959).
Acetaldehyde is a normal by-product of alcoholic fermentation. Acetaldehyde retention is
much greater when SO2 is added before the fermentation (Keilhofer and Wurding, 1960).
The primary source of acetaldehyde is from enzymatic process, i.e., in the presence of
yeast (Kielhofer and Wurding, 1960). Acetaldehyde reacts with ethyl alcohol to form
acetal, a substance with a strong aldehyde like odor, found very little in wines.
The tartaric, malic and citric acids of the must are found in the resulting wines but in
decreased amounts. They are important constituents of wine not only for their acid taste but
also they protect the wine from spoilage, maintain the color, and are themselves sometimes
attacked by microorganisms. Malic acid disappears during alcoholic fermentation to the
extent of 10 to 30%.
Succinic acid is a product of alcoholic fermentation. Lactic acid has a slight odor and is a
weak acid. It is a constant by-product of alcoholic fermentation, 0.04 to 0.75 g/L. Carbonic
acid constitutes a very special case for both still and sparkling wines. It has no odor and
very little taste. But it does have a feel and disengagement of the bubbles from wine
probably brings more oxygen away from the surface of wine (Amerine et al., 1967).
The end of fermentation is signaled by a clearing of the liquid, by a vinous taste and aroma,
and by a drop in temperature, and can be confirmed by checking degrees balling (sugar
residual) (Douglas and Considine, 1982).
25
2.12.4.3 Factors influencing fermentation
Various factors influence the course and consequence of the fermentation. These are
briefly discussed below.
2.12.4.3.1 Yeast culture
Yeast culture plays important role in winemaking. The pattern and end products of
alcoholic fermentation are greatly affected by the type of yeast culture utilized. The natural
wine culture and wine culture also produce wine with differing chemical constituents,
which may alter the organoleptic qualities of wines. Natural yeast flora of wine (i.e. raisin
culture) is a mixed culture, containing the wine strain of wine yeast, Saccharomyces
cerevisiae var. ellipsiodeus. It is said that the mixed flora produce wines with motalre
complex distribution of aroma components than wine fermented with S. cerevisiae (Reed,
1987).
Several species of Saccharomyces are the more important yeasts for winemaking, and
they constitute the true wine yeasts. The physiological properties of the yeast culture are of
importance in winemaking (Prescott and Dunn, 2004). The strain of yeast to be used for
alcohol fermentation should possess the following selective features:
1. Should be a sufficient strain. In other word, it should produce a large quantity of
alcohol.
2. It should be a fast growing strain.
3. It should have a high tolerance to alcohol, as well as to osmotic pressure.
4. It should possess uniform and stable biochemical properties.
2.12.4.3.2 Sugar and its concentration
Generally, monosaccharides are the normal and preferred substrates for the alcoholic
fermentation by yeast. The concentration of sugar determines the rate of fermentation.
High sugar concentration exerts high osmotic pressure which has negative effect on yeast
cells since both growth and fermentation activities are lowered. The inhibition is further
increased by ethanol which is formed during fermentation. The tolerance of high sugar
concentrations differs for various yeast species (Prescott and Dunn, 2004). The optimum
sugar concentration for maximum speed of fermentation is fairly low, perhaps only 1 or 2
percent. The maximum alcohol content in a single fermentation is obtained with musts of
from 25 to 35 percent sugar. The maximum alcohol content obtainable in normal winery
26
practice is about 16%; however, this varies with strain of yeast, temperature, conditions of
aeration, and method of conducting fermentation. The rate of fermentation is rapid below
25% sugar concentration of the must. Above 25% sugar concentration, the fermentation
gets retarded and at even higher concentration i.e. about 70%, most wine yeast will not
ferment the sugar. The inhibitory effect of high sugar is partly owing to the osmotic effect
(Amerine et al., 1967).
2.12.4.3.3 Sulphur-dioxide
The biological effect of SO2 comprises an inhibition of undesirable the microorganisms of
the must including acetic acid bacteria and lactic acid bacteria, which affect the course of
fermentation and quality of wine negatively. The chemical effect of SO2 is to bind
acetaldehyde which is formed during fermentation and which has undesirable organic
properties. Further, SO2 is added to prevent oxidative reactions of enzymatic or non-
enzymatic nature. For must with low total acidity, it is often desirable to use So2 to inhibit
malo-lactic fermentation. The SO2 is also desirable to suppress undesirable yeast species
such as Kloeckera apiculata and Metschnikowia pulcherrima on the must to retain good
wine quality. SO2 has also a direct effect on the course of the fermentation by
Saccharomyces yeasts. It delays the onset of fermentation, and the lag period is longer the
greater the amount of H2SO3 added to the must (Prescott and Dunn, 2004). However in
spite of its some desirable properties, SO2 is never added in base wine for brandy
manufacture due to its adverse effects on the quality of volatile acids is a advantage of
fermentations under CO2. Also, the metabolism of lactic acid bacteria is not inhibited
which may result malo-lactic fermentation and its undesirable consequences (Koch et al.
1953). In alcoholic media, the inhibition of yeast growth due to CO2 pressure is increased.
At relatively low CO2 concentrations of 0.6 to 1.8 g per liter, the growth is inhibited.
However, this effect depends also on the original yeast cell counts in the medium, and this
is also true at higher CO2 concentrations (Haubs et al., 1974).
2.12.4.3.4 Acids and pH
Yeasts are not very sensitive to the amounts of fixed organic acid but there may be some
effect of organic acids on the by-product of alcoholic fermentation (Amerine et al., 1967).
Microbiologically, the low pH (4.5 or below) is considered a favorable and selective factor
for wine fermentation. Most undesirable bacteria are inhibited at lower pH. For yeast, a pH
27
range between 3 and 6 is most favorable for growth and fermentation activity. A change in
pH can affect the formation of fermentation by-products. For instance, at higher pH values
the concentration of glycerine is increased. There is a positive relationship between the pH
of the must and the formation of pyruvic acid (Rankine, 1967A).Within the range from pH
3 to 4, there is a noticeable effect on lag phase and fermentation activity. At higher pH
values, the lag phase is reduced and fermentation activity increased (Ough, 1966A, B). The
effect of pH on growth and fermentation activity depends also on the concentration of
sugar and ethanol (Neish and Blackwood, 1951; Trautwein and Wassermann, 1931).
2.12.4.3.5 Temperature
The optimum temperature for fermentation by most wine yeasts is between 71.6oF and
80.6oF (Schanderl, 1959).However, temperature has many other effects besides its direct
effect on yeast growth and activity. These are due to losses of alcohol and aromatic
constituents at higher temperatures and to the by-products formed as well as to direct
effects on the efficiency of fermentation. Temperature affects yeast and consequently the
course of wine fermentation considerably, and a number of factors should be considered
for the selection of proper temperature. The fermentation metabolism of yeast can be
carried out within a rather large temperature range. Maximum value for S. cerevisiae is
near 40-45oC (White and Munas, 1951) and minimum temperature approaches to 0oC
(Osterwalder, 1934; Saller, 1955). Temperature also affects the formation of by-products.
With higher temperature within the 15-35oC range the concentration of glycerin, acetone,
2, 3-butanediol and acetaldehyde increase (Lafone, 1955; Rankie and Bridson, 1971).
Similarly, formation of acetic acid and other volatile acids, pyruvic acid and 2-ketoglutaric
acid also increase with increase in temperature. Whereas the formation of higher alcohols
decreases with increase in temperature. Whereas the formation of higher alcohols decreases
with increased the fermentation temperature having a maximum concentration at 20oC
(Dittrich, 1977). The temperature sensitivity of yeast is also affected by the ethanol formed
during fermentation.
2.12.4.3.6 Nitrogen
Yeasts readily assimilate amino acids but proteins can be hydrolyzed and used for cell
growth. Between 50 to 70% of total nitrogen of musts can be assimilated by yeasts
(Tarantola, 1955). The quantity of nitrogenous substances is entirely adequate for a
28
vigorous fermentation, and under normal circumstances there is even excess. Generally,
nitrogen is not required for grape juice, but fruit musts are often deficient in nitrogen. So,
urea or ammonium phosphate must be added. Nitrogen source addition is used to check the
formation of fusel oil, which is formed due to the action of yeast on amino acids. The
member countries of European economic country permit the addition of up to 30 gm/hL of
ammonium phosphate or ammonium sulfate to provide additional nitrogen in readily
assimable form (Reed, 1987).
2.12.4.3.6 Minerals and growth factors
The normal course of alcoholic fermentation requires magnesium, potassium, zinc, cobalt,
iodine, iron, calcium, copper and anions of phosphorous and sulfur. For growth alone
yeasts require copper, iron, magnesium, potassium, phosphorus, and sulfur. Adequate
amounts are supplied by grape and fruit juices. The presence of excessive iron (over
6p.p.m.) or copper hinders the fermentation of sparkling wines (Schanderi, 1959). Some
desirable growth factors for yeast are biotin, inositol, nicotinic acid, pentothenic acid, p-
aminobenzoic acid, pyridoxine and thiamine (Karki, 2001).
2.12.4.3.7 Oxygen
Oxygen is necessary for the maximum growth of yeast. But alcoholic fermentation is best
in an anaerobic condition. Here less of sugar is used by the yeast in respiration and there is
no oxygen to interfere with enzymatic activity. Aeration during normal fermentation may
results in wine with higher aldehyde content and darker color (Amerine et al., 1967).
2.12.4.3.8 Ethanol toxicity
Yeasts show some adaptive responses to the challenge of ethanol toxicity. The adaptive
behavior of yeast to ethanol response is also found in the relative resistance of the cells to
ethanol formed during fermentation, in contrast to the high sensitivity of cells to ethanol
supplementation. The most important response is that to the major toxic effect, the
disruption in the membrane permeability and change in fluidity. Increased ethanol
concentration can cause a decrease in yeast viability, reduction in yeast growth and
reduction in the rate of ethanol production. Slapack et al. reported that wine range of
cellular function is affected by ethanol, including inhibition of solute uptake, denaturation
and inhibition of glycolytic enzymes, uncoupling of oxidative phosphorylation and the
29
induction of peptic yeast strains. Saccharomyces cerevisiae may tolerate up to 17% by
volume ethanol concentration (Ribereau-Gayon and Peynaud, 1960).
2.12.5 Problems during fermentation
Different problems may arise during fermentation such as stuck fermentation, off-flavors
production, methanol production, and contamination with undesirable microorganisms.
There are two general classes of problems for winemakers that can arise during the
alcoholic fermentation: sluggish or stuck fermentations and off-flavor production.
2.12.5.1 Stuck fermentation
Premature arrest of alcoholic fermentation is an occasional but continuing problem for
wine makers. It may manifest itself as sluggish activity during mid and later phases of
alcoholic fermentation. Whereas in other cases cessation of fermentation activity may be
abrupt. In either case, the resultant wine may have perceivable (an often objectionably
high) levels of sugar with decreased production of alcohol. The causes of sluggish and
stuck fermentations include fermentation at temperature extremes, nutritional deficiencies,
osmo-regulation, ethanol toxicity, and in low-temperature fermentation, long-term
anaerobiosis. Such problem is generally treated with addition of deficient nutrition such as
nitrogenous compounds e.g. di-ammonium phosphate, and provision of optimum
temperature along with aeration for the reactivation of yeast (Kenneth, 1997).
2.12.5.2 Production of off-characters
Saccharomyces strains have also been implicated in the production of certain volatile
phenols in wine (Chatonner et al. 1993). During fermentation, production of off-characters,
off flavors or off aroma compound detract from overall wine quality. An important class of
spoilage compounds is sulfur-containing volatiles which have very unpleasant odors.
Although they are produced in traces, they cause damaging effect on the quality. Foremost
among the sulphur containing volatiles is hydrogen sulfide (H2S) (Baulton, 1997). To
prevent this problem very careful control of fermentation conditions is worthwhile.
30
2.12.5.3 Methanol production and its quality
Small amount of methanol is inevitably present in brandies, but if significant quantity is
formed during fermentation, large accumulation may result in distilled product which may
be detrimental to health. Methanol is produced by the demethylation of pectin present in
the substrate by fruit pectin esterase enzymes. Yeast does not form an enzyme capable of
hydrolyzing pectin and consequently the reaction does not commonly occur in fruit
fermentation but the fruit itself contains this enzyme. Methanol is very toxic to humans
with a fatal internal dose of 60-250 ml. The methanol production can be prevented by
inactivating the fruit pectin esterase enzymes before fermentation with heat treatment and
by obstructing the contamination of the fermentation with molds and bacteria.
2.12.5.4 Activity of undesirable microorganisms
Low pH values of the must are inhibitive for most of the bacteria but two types of bacteria
viz. lactic acid bacteria and acetic acid bacteria, which may start malo-lactic fermentation,
metabolizing the malic acid to lactic acid and CO2. The malo-lactic fermentation is
desirable in some cases, but generally it lowers the acidity causing rise in pH and
susceptibility of wine to further spoilage. Similarly, lactic acid bacteria ferment the sugar
into lactic acid and other volatile acids, causing an undesirably high acidity. Acetic acid
bacteria are aerobic and if they get favorable condition, they grow on the must and change
the produced ethanol into acetic acid (Reed, 1987).
2.13 Racking
After completion of fermentation, the wine must be separated from the dead cells, which
decomposes and give off flavors and odors to wine (Andrew, 1980). This dead yeast settle
at the bottom of the fermentation vessel and the wine is carefully transferred (siphoned) to
other vessel without disturbing the dead yeast leaving some wine at the bottom called lees.
The advantages of racking are:
• It helps removing CO2.
• It raises O/R potential, which retards the formation of H2S.
• It clarifies the wine.
31
2.14 Clarification and fining
Clarification by conventional racking process is a long process. To hasten this, certain
agents commonly called fining agents are added during racking. Fining is a traditional
method of bringing about clarification. Fining agents may be used during ageing as well.
They not only clarify the wine (by physical adsorption) but also help to remove excess
tannins (Rai, 2005). The purposes of clarification and fining during wine processing
include removal of excessive levels of certain wine components, achieving clarity, and
making that clarity stable especially from a physiological viewpoint. The materials used for
these reasons are collectively referred to as fining agents. Examples of such fining
reactions are: This is a process of converting cloudy wine into clear wine. This may be
done by adding gelatinous substances such as icing glass, egg white, bentonite and tannin.
Pectin hydrolyzing enzymes are also used in the clarification of wine (Andrew, 1982).
After clarification, the wine is passed through fine filters for filtration. The pad filters are
most common. In order to increase filter life, diatomaceous earths are added to wine during
filtration. These mix with mucilaginous materials and maintain the capacity of the filter for
longer times i.e. increase filter capacity. Recently membrane filters have been widely
employed for wines. These have uniform but small pore size so that a very large percentage
of the filter-surface is available for filtration. They also greatly reduce the number of
bacteria (Johnson and Peterson, 1974).
2.15 Stabilization of wine
Because of the unknown nature of the wine, it is generally good practice to stabilize them
against microbiological changes by use of antiseptics such as sorbic acid or its potassium
and sodium salts in amounts ranging from 300 to 1000 p.p.m. An alternative is to
pasteurize the wines after bottling. Another alternative may be to flash pasteurize, fill into
clean bottles, and seal using clean closures (Chan, 1983).
2.16 Maturing and aging of wine
This is one of the most interesting and one of the most important, yet one of the most
complex processes of wine making. This takes place naturally by retaining the wine in oak
barrel for one or two years to gain maturity and pick up soft and mellow characters from
the oak wood. Andrew (1980) found that maturation can be artificially induced by
32
agitation, heating, refrigeration and electrical impulses. The bouquet and aroma of wine are
developed during aging (Banwart, 1987).
Aging of wine for long periods of months to years produces desirable changes in body
and flavor of wine. In addition, malic acid of grape juice is fermented by lactobacilli during
aging to give lactic acid and carbon dioxide and also decrease the acidity (Sivasankar,
2005).
Aging is one of the most interesting and important yet one of the most complex process
in winemaking. Newly fermented wine is cloudy, harsh in taste, yeasty in odor and without
the pleasing bouquet that develops later in its history (Amerine et al., 1967). The wine is
aged to reduce the acidity and to develop a characteristic bought. The main acid in most
wines is tartaric acid but, in some red wines, malic acid is present in a high concentration.
In these, secondary malo-lactic fermentation by lactic acid bacteria converts malic acid to
lactic acid to reduce the acidity and to improve the flavor and aroma. Lactic acid bacteria
produce small amount of aldehydes and lactic and acetic acids, which give the product a
characteristic aroma and flavor (Fellows, 1990). Aging of wines improves the flavor and
bouquet due to oxidation and formation of esters. These esters of higher acids formed
during aging give the ultimate pleasing bouquet to the well aged wine. Aged wine may be
polished by filtration to give a clear, bright appearance prior to bottling (Desrosier and
Desrosier, 1978).
2.17 Bottling
This is done before the blended wine has lost its bouquet, fineness, quality and color.
Bottles are cleaned and dried with hot air. Cool and dry weather is chosen for this purpose.
Bottles are closed with a fine, soft supple cork applying pressure with the finger. Corks are
finally sealed with Spanish wax (Andrew, 1980).
2.18 Pasteurization
Pasteurization is the process used to kill microorganisms present in the wine so that
fermentation is stopped. Pasteurization is applied in one of the three ways:
1. By flash pasteurizing and returning to the storage tank.
2. Flash pasteurizing into the final bottles and
3. Pasteurization by heating the filled and sealed bottles.
33
The time temperature relationship for pasteurization of wine is: vegetative yeast cells are
killed at about 40oC while yeast spores are only killed at 57oC (Desrosier and Disrosier,
1978). The quality of some wine is reduced by pasteurization while that of other may be
improved. Pasteurization inactivates the enzymes but injures the quality of the product
(Johnson and Peterson, 1974).
2.19 Finishing
The traditional method of finishing the wine was to turn the bottles on end, place them in
racks at about 45o angle and turn them to the left and right daily to get the yeast deposit
into the neck of the bottle and on the cork. The process is called riddling “reumage”. The
temperature of the whole bottle is then reduced to about 30oC to 40oC. The neck of the
bottle containing the yeast deposit is then frozen (by placing in brine or other freezing
solution). When the cork is removed, the solid plug containing the yeast is ejected. This is
called disgorging (Johnson and Peterson, 1974).
2.20 Storage and ageing of wine
Actually racked wine contains some suspended particles. Racked wine is flash pasteurized
in order to coagulate the suspended particles. After pasteurization it is kept at room
temperature for 1-2 days, then at -3 to -4oC for 2-5 days. Then it is filtered in the cold state
(-3 to -4oC) and transferred to storage tank. Wines are aged in bottles, barrels, tanks or
puncheons. The tank may be wood, concrete or metal ((Dhakal, 1988).
A wine cellar should be maintained at a uniform temperature of 60oF and a humidity of
50%. When stored, each bottle of wine must be laid in a horizontal position so that the
wine keeps the cork moistened. The room should be darkened, free from dirt, and
mechanical or sound vibrations (Smith and Milner, 1974).
The purposes of storage and ageing are:
• For the development of body, flavor and bouquet,
• To aid the clarification.
Ageing of wines improves the flavor and bouquet due to oxidation and formation of
esters. These esters of higher acids formed during ageing give the ultimate pleasing
bouquet to well aged wine. Aged wine may be polished by filtration to give a clear, bright
appearance prior to bottling (Desrosier, 1982). The period of ageing depends upon quality
of wine. For example- dry wines are aged for 2 years, and fine wines for 5 years.
34
2.21 Wine made from different raw materials
Wine can be prepared from different raw materials. It can be made from different fruits
(grapes, apple, pears, bael, guava, banana, pineapple, pumpkins, etc.) and roots (ginger,
potato, calocassia, etc.). Many researchers have prepared wines from different raw
materials in CCT, Hattisar, Dharan. Dhakal, (1988) prepared wines from ginger and banana
having varied recipes fermented by yeast isolated from murcha. TSS and pH were
optimized for banana and ginger wines. Banana wine was found best having 17oBrix TSS
and 4.5 pH. Similarly, ginger wine having 22oBrix and 5pH was found best. The alcohol
content of ginger and banana wines was found to be 7.06% and 8.39% (v/v) respectively.
He found that 17-20% sugar concentration, 100-200 p.p.m. SO2, 25-30oC temperature and
4.5-5pH were suitable for appreciable starter activity.
Shakya, (2002) prepared bael wines from bael pulps obtained by hot and cold extractions.
The bael wine prepared from hot extracted pulp was found to be better than the cold
extracted. Bael wine from mash of 25% pulp content was the best. Fining agents tannin and
gelatin produced exceptional clarity. The bael wine contained 11%(v/v) alcohol, 0.12%
volatile acidity, 0.49% fixed acidity, 9.5g/100L methanol, 225 mg/L esters, 280 mg/L
aldehydes and 193 g/100L total higher alcohol.
Gubhaju, (2006) prepared wine from Rhododendron flower using wine yeast. Effect of
fresh and dried flower on quality of wine was studied. She found that use of raisin and
brown sugar did not improve the quality of wine. TSS of 20oBrix and pH of 4.5 were found
optimum for the preparation of Rhododendron wine using dry flower and S. cerevisiae.
Average alcohol content and esters of the prepared wine were found to be 11.03% (v/v)
and 3.81 mg/L respectively.
Dhakal, (2007) prepared wine from palm sap using baker’s yeast. Wine made from mash
with 4.5 pH and 20oBrix was found to be most acceptable. Total solids (%m/v), sp. gr. (at
25oC), alcohol content (%m/v) and ash content (%m/v) were found to be 0.13, 0.9529, 36.5
and 0.005 respectively. Similarly, total aldehydes (as g acetaldehyde), esters (as g ethyl
acetate), fusel oil (as g amyl alcohol), total acidity (as g lactic acid), volatile acidity (as g
acetic acid) and fixed acidity (as g lactic acid) were found to be 0.525, 44.1, 84.46, 281,
162 and 37.47 per 100 L of ethanol respectively.
35
2.22 Fining agent and its types
The material which is used to achieve clarity of wine is called fining agent. The fining
agent has several adsorption sites on each head or molecule and a number of solute
molecules are either adsorbed to its surface or exchanged into its inferior. Several of the
agents currently in use (such as the proteins and the gums) are colloidal in nature and as the
adsorption occur, resulting in precipitation of the solute/agent complex from the solution.
The amount of solute removed by a certain addition of an agent will depend on the
solute/agent pair as well as the concentration of the solute in the wine and the quantity of
the agent added. The fining agents can be classified into the following groups:
2.22.1 The Proteins
The purpose of adding a protein preparation to wine is to soften or reduce the wine’s
astringency or reduce its color by the adoption and precipitation of polymeric phenols and
tannins. Although it is rarely practiced today, white wines can be clarified by adding a
protein followed by tannin due to the co-precipitation that occurs. All of these proteins
come from natural sources usually in a partially purified form. The four most commonly
used proteins for wine precipitation are casein, gelatin, albumin, and isinglass. Their
properties are summarized in Table 2.4.
36
Table 2.4 Typical ranges of application of fining agents.
Agent Common Range of Application (mg/L)
White Table Wine Red Table Wine
Casein 60 to 120 60 to 240
Albumin N/A 30 to 240
Isinglass 10 to120 30 to 240
Gelatin 15 to 120 30 to 240
Bentonite (Na form) 120 to 720 N/A
Silica Sol 40 to 200 40 to 200
PVPP 120 to 240 120 to 480
Agar/ Alginate 120 to 480 120 to 480
Activated Carbon 120 to 600 120 to 480
(Source: Boulton et al., 1997)
2.22.2 The Earths
There are a number of clays: silica, alumina matrix with exchangeable cations, bentonite
etc. The clays (silica, alumina matrix) have been considered as alternatives to bentonite and
these include kaolin, Spanish earth. They generally have a lower adsorption capacity and
therefore are not preferred in winemaking applications.
2.22.2.1 Bentonite and its properties
Bentonite is widely used for the adsorption of proteinaceous material from wines.
Bentonite was originally introduced as a means of clarifying wines and vinegars (Saywell,
1934A.B) and its application to inducing heat stability in white wines came several years
later. Bentonites are mined from several areas of world and come in different levels of
purity, particle size, adsorption and swelling capacity. Bentonite is natural clay that is
classified as a montmorillonite, with a general composition of the form: Mg, Ca, Na,
Al2O3.5SiO2.nH2O (Siddiqui, 1968). The source of the bentonite influences its properties
slightly and the main difference lie in the proportion of Mg++, Ca++, and Na+ in the
lattice. Bentonite has a structure which expands after contact with water and preparations
have optimum adsorption after two days of soaking. The limited cation exchange capacity
37
poses particular problems with the removal of negatively charged and neutral protein
fractions from wines. Bentonite is essentially inert with respect to the phenolic components
in wine except for cationic anthocyanins. There is little effect of temperature on the
adsorption (Jacob, 1968; Blade and Boulton, 1988). Bentonite may indirectly bind phenols
that have complexed with proteins. Bentonite may affect red wine color by binding with
positively-charged anthocyanin monomers and may result in color decrease depending
upon the age of the wine.
Bentonite may also remove more color in younger wines because of the greater action on
the colloidally colored material found in the younger wines (Bergeret, 1963). Addition of
bentonite to red wines at levels of 6 to 12 g/hL (0.5 to 1 lb/1000 gal) improves membrane
filterability due to reduction in colloidally suspended particles. Bentonite fining of juice
may remove peptides and some amino acids, potentially affecting rate and completion of
fermentation. Bentonite fining is known to indirectly prevent or impede formation of
copper, and possibly iron casse, this is probably due to removal or reduction in levels of
proteins and peptides known to be involved in the formation of haze and precipitate.
2.22.2.2 Preparation of bentonite
Preparation of bentonite greatly impacts its activity toward proteins. In solution, bentonite
swells to many times its dehydrated dimensions. Its activity is much like that of a
multiplateted, ong-chain, linear, negatively-charged molecule (Singleton, 1967). During
the hydration phase, charged platelets repel each other and begin to separate. Water
molecules partially neutralize and separate exposed surfaces, exposing a large matrix of
reactive surface. The presence of water molecules within the network prevents flocculation
and precipitation. The water used in hydration phase should have a low mineral content.
Dissolved metal cations present in slurry water preferentially replace sodium ions on the
clay surface and detrimentally affect the hydration, viscosity, and binding capacity of the
bentonite (American Colloid Co.). Typically, the bentonite-to-water ratio for slurries is 5-
6% (w/v). Heating non-agglomerated bentonite allows the platelets to fully separate and
slurry resembles a gel. Bentonite additions, especially those exceeding 48g/hL (4 lbs/1,000
gal), may strip wine flavor, body, and in the case of young red wines, significant color.
Further, it may impart an earthy character to the wine. Some winemakers choose to ferment
settled juice in contact with benttonite to aid protein stability and to eliminate or reduce the
38
amount of bentonite needed to stabilize the wine. The procedure for the fermentation of
white juice in contact with bentonite used in USA is as follows:
1. Settle juice to remove non-soluble solids by refrigeration and/ or fining agents (A
high solids level could foul the bentonite utilized during fermentation and reduce
overall efficiency). Add the desired quantity of bentonite in-line while racking into
the fermentor.
2. Add yeast nutrient and any needed sugar and/or acid where allowed.
3. Add yeast inoculum to juice surface.
2.22.3 Synthetic Polymers
Materials such as polyglycine, polyamide (nylon), and polyvinyl-polypyrrolidone (PVPP)
are synthetic products with available carbonyl oxygen atoms at the surface that act as
adsorption sites. Nylon and PVPP are both insoluble white powders that have been used in
wine. The more efficient adsorption of PVPP has led to its preferential use (Caputi and
Peterson, 1965; Rossi and Sigleton, 1966). The agents are generally added in a batch
treatment and commonly settled or filtered out of the wine and discarded after one use. The
catechins are involved in the chemical browning of white wines and are thought to be
particularly bitter in nature above their sensory threshold level of 20 mg/L (Singleton and
Noble, 1976).
2.22.4 The Colloids
The colloids that are used for wine clarification are classified into two groups:
2.22.4.1 Natural Polysaccharides
The polysaccharides, agar and acasia (gum arabic), both have protective colloid properties
and can partially neutralize surface charges on other naturally dispersed colloids, thereby
allowing them to either dissolve or to coagulate. The polysaccharides of this kind are
especially useful in neutralizing the charge of other haze components of what are generally
referred to as protective colloids, one polar or charged entity is adsorbed to the outer
surface of another, causing the overall complex to repel like species and causing a
suspension to occur. In wines and juices natural polysaccharide contents are in the range
200 to 1000 mg/L (Usseglio-Tomasset, 1976; Villettaz, 1988; Feuillat, 1987;
Wucherpfernnig and Dietrich, 1989).
39
2.22.4.2 Ferrocyanide Preparations
The application of ferrocyanide salts for the removal of transition metal cations from wine
has been widely practiced in Europe for more than 50 years. Sometimes referred to as
Moslinger fining, after its inventor, the form used is potassium ferrocyanide, K4Fe(CN)6.
The ferrocyanide salts of most metals are blue (hence the term blue-fining), sparingly
soluble, and when used properly, the residue should be less than 0.02 mg/L (Wurdig and
Woller, 1989).
2.22.5 Alternative Methods of Metal Depletion
The removal of metals could be achieved by the use of immobilized forms of ferrocyanide
or alternatively, other chelating materials. There are presently a number of chelating resins
available commercially, but several of them have limited chelating functions at pH values
less than 4. Alternative polymeric materials based on 1-vinylpyrrolidone and 1-
vinylimidazole have also been suggested for the removal of metals from wine (Fussnegger
et al., 1992). The polymer containing a ratio of the pyrrolidone to imidazole of 9:1 gave the
best results, although a significance pH rise occurred at treatment levels that were required
to lower the copper content to below 0.2 mg/L, the level generally considered to be
acceptable.
2.22.6 Activated Carbon
The activated carbons have high and broad affinities particularly for benzenoid and non-
polar substances. They are used to remove color pigments and a wide range of phenolics
but are rather nonselective in their adsorption (Singleton, 1964). They do not adsorb
substances such as sugars and amino acids which are highly water soluble. They are not
generally used and offer no benefits to most wines. They adsorb a range of other trace
constituents including some vitamins and this could have secondary effects on
microbiological stability. The carbons are usually sold as either decolorizing or
deodorizing forms. The treatment levels are determined by a dose-response trial on the
wine in question with the specific carbon.
2.22.7 Silica Suspension
Silica suspensions, or sols, are most often used in clarification and settling applications,
particularly with apple and fruit wines. In such cases, the silica sol preparations which vary
40
with the loading and wine concerned. The treatment limit in the United States is 2.4 g/L of
a 30% by weight silica solution.
2.22.8 Copper Sulfate
Copper sulfate is used to remove H2S and thiols from wines and the level of addition
should be less than 0.5 mg/L. The residue of copper should be less than 0.5 mg/L in the
United States and 0.2 mg/L in the most countries. Copper sulfate can be used in
conjugation with a sulfite/ascorbate addition to remove disulfites from wines.
2.23 Components of wine
Being produced from complex material, wine contains innumerable components. The chief
component of wine is ethyl alcohol but many other components specially present on the
mash of the fruit or may form during fermentation. Further more, other components are
formed during ageing or are extracted from the wood.
2.23.1 Ethanol
Ethanol (C2H5OH) is completely miscible with water and is an excellent solvent for
odorous materials such as essential oils, esters, tannins, various acids and certain other
organic compounds. It has a slight sweet taste and moderates the taste of acids. A de-
alcoholized wine is much more tart than the same wine with its alcohol. The odor
threshold, according to Berg et al. (1955B) is 0.004 to 0.0052 gm. per 100 ml. Most of the
alcohol in wines result from fermentation, a little may result from hydrolysis of glycosides
during prolonged ageing. The alcohol content varies from 5% up to 21% (v/v). Natural
wines contain 8.5 to 16% ethanol by volume. The legal limits for alcohol vary markedly
for different countries and are usually related to the tax structure (Amerine et al., 1967).
2.23.2 Methanol
It is generally agreed that methanol, CH3OH, is not generally produced by alcoholic
fermentation, but is primarily derived from hydrolysis of naturally occurring pectin in
fruits by pectolytic enzymes. Methanol is shown to be higher in wines from macerated
grapes than from non-macerated fruit. There is no change in the methanol content during
the fermentation of a white must. Methanol increases in red must during fermentation. The
methanol content is not related to the pectin content and that fermentation does not change
41
the methanol content. The amount of methanol in wines ranges from traces to 0.635 gm.
per liter, average about 0.1 (Amerine, 1954). The sensory importance of methanol has not
been studied.
2.23.3 Higher alcohols (Fusel oils)
The higher alcohols constitute a part of flavor in wine. The higher alcohols account for the
major portion of the products of yeast metabolism. At very low concentrations the higher
alcohols may play a desirable role in sensory quality. Higher concentrations lower the
quality of the wine (Wagener and Wagener, 1968). But the complexity of the substrates
rarely permits clear-cut conclusions (Guymon and Heitz, 1952). The higher alcohols
always present are 1-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, 2-methyl-1-
butanol, 3-methyl-1-butanol, 1-pentanol, and 1-hexanol. Higher alcohols which are not
present or only in traces amounts include 2-propanol, 2-methyl-2-propanol, 3-methyl-2-
butanol, 2-pentanol, 3-pentanol, and 2-hexanol (Usseglio-Tomasset, 1964). The oxidative
conditions during fermentation favor higher alcohol production. The presence of pomace,
as in red wine production, aerates the wine and thus leads to greater amounts of higher
alcohols (Guymon et al., 1961). The amount of higher alcohols produced is less when
ammonium phosphate is added prior to fermentation.
2.23.4 Carbonyl compounds
Carbonyl compounds are always present as part of the aroma of wine (Rapp et al., 1973;
Schreier et. al. 1976; Webb, 1967). These are mainly aldehydes which are formed during
fermentation as intermediates in the formation of alcohol from sugars and amino acids; but
some ketones also occur (Lehtonen and Suomalainen, 1977). Acetaldehyde is a normal by-
product of alcoholic fermentation. Aldehyde retention is much greater when SO2 is added
before the fermentation and especially high when SO2 is added during fermentation. The
primary source of aldehydes is from enzymatic processes, i.e., in the presence of yeast.
Non-enzymatic production of aldehyde in white wines is very small, especially in the
absence of iron (Kielhofer and Wurdig, 1960B). The amounts found in newly-fermented
wines are below about 75 mg per liter, it has little sensory importance, especially so since
most of our wines have SO2 added which fixes most of the aldehyde. However, it has a
pronounced odor and a threshold is of only 1.3 to 1.5 mg. per liter in water (Berg et al.,
1955A). But the thresholds are of 100 to 125 p.p.m. The diketone, diacetyl, which is a well
42
known flavorant in many foods, occurs in wine where it is produced by yeasts during the
alcoholic fermentation. The diacetyl produced during the fermentation is immediately
metabolized by the yeasts (Suomalainen and Ronkinen, 1968).Its content in fermenting
mash, therefore, is zero. It rises slightly in the wine after the yeast is removed. Sherry has
usually high concentrations of aldehydes, yet there seems to be no correlation between
their concentration and the quality of the wine (Amerine et al., 1980).
2.23.5 Esters
Wine, as well as other fermented beverages, is rich in esters. Esters are very important for
the aroma of the wine because of their intense aroma at relatively small concentrations. A
total of more than 50 various esters have been identified in wines. For beverages with
relatively low ethanol concentrations, such as wine, enzymatic reactions are responsible for
the formation of esters, while strictly chemical reactions do not proceed (Nordstrom,
1964). Yeasts determine the composition and the amounts of the esters formation. The
effect of esters on wine quality is difficult to quantify. There is a tendency toward higher
quality for wines with higher ester concnetrations (Wagener and Wagener, 1968). Only
ethyl acetate seems to be important-below about 200 mg. per liter it may be a desirable
odor but above this it appears to give a spoiled character to the wine. Both neutral and acid
esters are found in wine. The total esters in various wines vary between about 200 and 400
mg. per liter (as ethyl acetate).
2.23.6 Acids
The acids includes both volatile and fixed. Besides acetic acid and lactic acid, which are
normal by-products of alcoholic fermentation, formic, butyric, propionic and traces of
other fatty acids are present. Acetic acid is not only a by-product of alcoholic fermentation
but during the course of fermentation an appreciable amount may be utilized by the yeast.
Wine always contains some volatile free acids, mainly aliphatic acids. They occur in higher
concentrations in spoiled wines because of the activity of film forming yeasts, and
particularly of acetic acid bacteria and lactic acid bacteria. Volatile acidity refers to the
volatility with steam of the fatty acids. The volatile acidity thus includes the fatty acids in
the series starting acetic but excludes lactic, succinic, carbonic and sulfurous acids. The
volatile acids are produced mainly during the initial stage of fermentation, and more is
formed in presence of oxygen than in absence (Amerine et al., 1967). The determination of
43
volatile acidity as an indication of spoilage has become a part of the legal requirements for
wine standardization. The amounts of acetic acid produced during alcoholic fermentation
are small-usually less than 0.03 gm. per 100 ml. Bacterial action before, during, and after
fermentation may lead to much higher quantities of alcohol or occasionally to bacterial
attack on fixed acids include tartaric, malic, and citric acids. These acids of the must are
found in resulting wines, but decreased amounts. They are important constituents of wine
not only for their acid taste but also because they protect the wine from spoilage, maintain
the color, and are themselves sometimes attacked by microorganisms (Amerine et al.,
1967). Both pH and titratable acidity are important in determining sensory response to
sourness.
2.23.7 Glycerol
Glycerol is a by-product of alcoholic fermentation. Glycerol production is favored by
lower temperatures, higher tartaric acid content, and by addition of SO2. Glycerol is of
considerable sensory importance because of its sweet taste and its oiliness. A dry table and
red table wines contain 0.3 gm. and 0.8 gm. per 100 ml of glycerol respectively (Hienreiner
et al., 1955A).
2.23.8 Minerals
The inorganic constituents of wines are of considerable biochemical, technological and
physiological importance. Many are needed in alcoholic fermentation. Some are significant
in human nutrition-usually desirable so but in a few cases from toxic point of view so that
legal maxima are prescribed. Wines contain anions (bromide, chloride, fluoride,
phosphates, silicate, sulfate etc.) and cations (aluminium, arsenic, cadmium, calcium,
copper, iron, magnesium, manganese, sodium, potassium, rubidium, etc.). The anion and
cation balance of wine is made in winemaking (Amerine et al., 1967).
2.23.9 Pectins and gums
Finished wines have 0.3 to0.5 gm. per 100 ml of pectins and gums. The gums of wines are
generally arabans, anhydrates of arabinose and galactans. To remove pectins, pectolytic
enzymes are frequently used-either before or after fermentation. They do aid filtration and
reduce the pectin content. They also raise the galacturonic acid content and slightly
increase the methanol content.
44
2.23.10 Water and sugar
Their amounts are variable. Dry wine contains less than 0.12% sugar and sweet wine
contains up to 7% sugar.
2.24 Yield
The yield of alcohol is of great importance to the wine maker. According to the Gay-
Lussac equation theoretical yields of 51.1 per cent alcohol and 48.9 per cent carbon dioxide
are possible. It is obvious that this is biologically unobtainable and in practice will depend
on a variety of factors-amount of by-products, amount of sugar used by yeasts, sugars used
by other micro-organisms, alcohol lost by evaporation or entrainment (which in turn
partially depends on the temperature and the rate of fermentation), presence of air, stirring
or other movement of fermenting mass, and other factors. The yield is therefore not a fixed
quantity but will vary depending on the variables mentioned above. The best practical
yardstick for yield is therefore empirical studies made under carefully controlled conditions
(Amerine et al., 1967).
Kirk (1967) has found that roughly each percentage of sugar fermented yield 0.55% of
alcohol by volume. Under special condition of simulation, 16-18% alcohol can be reached,
but normally in commercial operation, 13-15% is the maximum (Johnson and Peterson,
1974).
2.25 Wine defects and spoilage
Wine defects include turbidity, cloudiness, precipitation and loss of color, coloration due to
metals such as iron, tin and copper and their salts. Microorganisms, both aerobic and
facultative, cause wine spoilage by imparting cloudiness, bitter characteristics, ropiness,
undesirable flavors high volatile acidity and low alcohol content. Wild yeasts, molds and
bacteria of the genera Acetobactor, Lactobacillus, Leuconostoc and Pediococcus cause
spoilage if wine (Sivasankar, 2005). Leuconostoc mesenteroids causes sliminess or
ropiness of wine as well as it increases the viscosity of wine (Parry, 1973).
Wine defects may be caused by micro-organisms or non microbial causes. Defects
include those due to metals or their salts, enzymes and agents employed in clearing the
wine. Iron, for example, may produce a sediment known variously as grey, black blue or
ferric casse and in white wine may be responsible for white precipitate of iron phosphate
termed white casse. Tin and copper and their salts have been blamed for cloudiness. White
45
wines may be turned brown and red wines may have their color precipitate by peroxidases,
an oxidizing enzyme of certain molds. Gelatin, used in clarifying wines, may cause
cloudiness (Frazier, 1967).
2.26 Wine and its health benefits
No other drinks, except water and milk, have earned such universal acceptance and esteem
throughout the ages as has wine.
Most of the world’s wines have been consumed with food or as food itself. Wines
reputedly aided in maintaining health not only because of their own nutritive value, but
also because they replaced inadequate wine or otherwise unsatisfactory water supplies,
(Peterson, 1971).
Medical studies have revealed a lot of health benefits of drinking wine.
We have probably heard about the 'French Paradox'. This finding concerns wine and health
and shows that the French have a lower incidence of coronary disease as we find in the
United States, despite the rich, high fat foods found in French cuisine. Many experts
attribute this to the regular consumption of wine in the French diet. Some wine and health
medical studies have shown that an occasional glass of wine can reduce the risk of heart
disease or stroke. Moderate wine consumption can reduce the risk of death by
cardiovascular disease, stroke, and cancer. Studies are still being conducted on the red wine
health benefits. Wine contains flavanoids, anti-oxidants that help to prevent free-radicals
from damaging cells. One in particular helps to prevent hardening of the arteries. Wine also
contains a substance called reservatrol. This substance has been shown to boost the
immune system, block cancer, and protect against cardiovascular diseases. These
substances are found in all wines, but there are more in red wine than in white wine, that is
why we are speaking particularly about red wine health benefits. With red wines, the
grapes are pressed, and the juice sits for a while with the grape skins and stems still
present. Because of this, the grape juice has a chance to leach more of the flavanoids and
resveratrol from the grape skins. So, red wines will have a higher concentration of anti-
oxidants than white. (Source:http.//www.metalimagination.com/historyofwine.html).
White wine contains more riboflavin than red wine (Morgan et al., 1987). While studying
the vitamin content in fermenting musts, Castor found that riboflavin increased,
panthothenate usually decreased, vitamin B6 slightly decreased, and biotin was largely lost.
Lucia (1954) reported that when wines are taken along with a good and balanced diet, their
46
content of thiamine, riboflavin, pantothenate, niacin and vitamin B6 contribute to total
nutrition. Wine has an anti-inflammatory and anti-oxidant substance called resveratrol,
which is effective against lung disease (Srilakshmi, 2007).
2.27 Brief Introduction of Ginger wine
Ginger Wine is an alcoholic beverage made from a fermented blend of ground ginger
(Zingiber officinale Rosco.) and raisins. The word drink is primarily a verb, meaning to
ingest liquids, see Drinking. ... Ginger is usually used to flavor a wine. It also contributes to
color of wine. Powder ginger is not used in wine making. It has many health benefits.
Ginger wine can be consumed by blending with whisky, brandy or rum. The first
documented appearance of Ginger Wine occurred with the foundation of 'The Finsbury
Distilling Company' based in the City of London in 1740.
(Source:http.//www.statemaster.com/encyclopedia/Ginger-wine).
Part III
Materials and methods
3.1 Raw Materials
The raw materials viz. raisin, ginger and sugar were procured from local market of Dharan.
Baker’s yeast (Saccharomyces cerevisiae) manufactured by Vitabe-Belgium bvba
Langerbruggekaai 37, 9000 Gent-Belgium was collected from Gorkha Department Store,
Itahari and true wine yeast (Saccharomyces ellipsoideus) was obtained from Makalu wine
industries (P.) Ltd., Basantapur, Tehrathum.
3.2 Optimization of TSS and amount of ginger in the fermentation mash
3.2.1 Preparation of mash
Ginger was washed and removed its skin by a knife. Raisin was sorted and washed in tap
water. The ginger and soaked raisin were flaked by iron mortar and pestle. The sugar syrup
was made with warm water, and then stained by muslin cloth.
The different fermentation mashes having 10% raisin of the total mash and 4.5 pH were
prepared as follows:
Table 3.1 Composition of different mashes.
Mash Ginger (%) TSS (oBrix)
1 1 16
2 1 20
3 1 24
4 1.5 16
5 1.5 20
6 1.5 24
7 2 16
8 2 20
9 2 24
The TSS of these mashes was adjusted with addition of sugar syrup and pH was adjusted to
4.5 by using 5% sodium bi-carbonate and citric acid solutions with a pH meter (Henna,
48
Portugal). All these mashes were pasteurized by heating t0 70-72oC for 15 minutes and
brought to room temperature (30oC) by cooling in tap water.
3.2.2 Pitching and agitation
One set of the prepared mashes was inoculated with baker’s yeast and another one was
inoculated with wine yeast at the rate of 1g/ Liter, and was filled into clean and boiled
bottles up to 2/3rd of their capacity. The bottles were then plugged by cotton, agitated and
kept for fermentation at room temperature.
3.2.3 Fermentation
The progress of fermentation was monitored by measuring the drop of TSS. After 5 days of
pitching, the TSS of the fermented mashes was measured by hand refractometer every day
till constant TSS was obtained. After 11 days from pitching, the fermentation was assumed
to be completed when the TSS ceased to drop further.
(a) (b)
Fig 3.1 Fermentation of ginger wines.
3.2.4 Racking, pasteurization and bottling
The clear wines were siphoned off from the lees in still pot using a sterilized polythene
pipe, and covered with metal dish and pasteurized by heating to 70oC for 15 minutes and
cooled to room temperature (30oC) by cooling in tap water. Bentonite suspension was
49
added at the different concentrations (0.5, 1 and 1.5g/L) for the clarification of the ginger
wines. The cold wines were racked and filled in to the pre sterilized bottles and kept in
room until needed for further analyses.
Fig. 3.2 Flow sheet for the preparation of ginger wine
Screening
Weighing
Washing and soaking
Flaking
Ginger
Washing
Skin removal
Weighing
Flaking
Mixing
Adjustment of TSS and pH
Pasteurization at 70oC/15 minutes
Cooling to 30oC
Addition of starter culture @ 1 g/L
Fermentation at 28-30oC/11 days
Racking
Pasteurization at 70-72oC/15 minutes
Bottling
Storage at room temperature
Analyses
Raisin
Addition of bentonite suspension (5%)
Clarification
50
0.5 g/L 1 g/L 1.5 g/L 0 g/L
3.2.5 Quality analysis
The quality of the prepared wines were analyzed by chemical analysis (TSS and alcohol
content) and sensory analysis (smell, taste, mouth feel, color and overall acceptance) by
ANOVA.
3.3 Selection of the best yeast
The optimized fermentation mash (20oBrix TSS, ginger 1% m/v and 4.5pH) was inoculated
with true wine and baker’s yeasts separately at the same rate 1g per liter.
3.4 Clarification of ginger wine using Bentonite
Both fermented ginger wines were mixed with bentonite suspension at the rate of 0.5, 1.0
and 1.5 g/L separately, stirred for 10 minutes in magnetic stirrer and left for overnight to
separate clear layers. Next day, the upper clear layer was racked into the next bottle gently.
Fig. 3.3 Clarification of ginger wine using bentonite.
3.5 Analytical methods
The moisture content of ginger was determined by distillation method as per AOAC
(2005). Reducing sugar, esters, aldehydes, acidities (total, fixed and volatile) and alcohol
content were determined as per AOAC (2005). TSS was measured by hand refractometer
and pH was measured by potable digital pH meter (Henna, Portugal). Turbidity of the
clarified wines was measured by turbidometer (Henna, Portugal).
51
3.6 Quality analysis of prepared wines
3.6.1 Sensory evaluation
Prepared ginger wines fermented by Baker’s and true wine yeasts were subjected to
sensory evaluation for consumer’s acceptability. Sensory attributes (such as smell, taste,
mouth feel, color and overall acceptance) were evaluated using a 9 point Hedonic scale
rating test ranging from dislike extremely (1) to like extremely (9) as described by
Ranganna (2001) by the help of semi-trained 15 panelists selected from those who were
familiar with alcoholic beverage. Samples were served in clean transparent labeled glasses.
Questionnaires and water for mouth rinsing between each tasting were provided. Sensory
evaluation sheet is given in Appendix III.
3.6.2 Statistical analysis
The determination was conducted in triplicates. The data were analyzed by using Genstat
programming (GenStat Discovery Edition 3, 2008) at 5% level of significance. The means
were compared using LSD method and t-test.
Part IV
Results and discussion
Raisin, sugar and ginger, available at local market of Dharan, were used for the preparation
of fermentation mashes. The ginger wines were prepared from the mashes having 10%
raisin, sugar concentrations (16o, 20o and 24 oBrix), ginger amounts (1, 1.5 and 2% m/v)
and pH of 4.5 by using baker’s yeast at room temperature. The pH was adjusted to 4.5 by
sodium bicarbonate or citric acid solutions. Similarly, TSS was adjusted to by using sugar
syrup. In the next experiment, the mashes having 10% raisin, 20oBrix TSS, 1% ginger and
4.5pH were pitched with true wine yeast and baker’s yeast separately. The fermentation
was allowed to proceed for 11 days at room temperature (28-30oC) until constant TSS was
obtained. After completion of the fermentation, the wines were analyzed for chemical
properties and subjected to sensory evaluation.
4.1 Effect of TSS and ginger amount on the chemical and sensory quality of ginger
wine
4.1.1 Effect on chemical characteristics
0
2
4
6
8
10
12
14
10 12 14 16 18 20 22 24 26
Initial TSS of the mash
Res
idua
l TSS
of g
inge
r w
ine
1% (m/v) ginger1.5% (m/v) ginger2% (m/v) ginger
Fig. 4.1 Effect of mash TSS on the TSS of the ginger wines.
53
0
2
4
6
8
10
12
14
0 0.5 1 1.5 2 2.5
Ginger amount, % (m/v)
Res
idua
l TSS
of t
he g
inge
r w
ine
16 Brix TSS20 Brix TSS24 Brix TSS
Fig. 4.2 Effect of ginger amount on the TSS of the ginger wines.
The final TSS of the ginger wines made from the mashes having initial TSS of 16o, 20o and
24 oBrix were found to be 6o, 7o and 11.7oBrix respectively. The ANOVA result showed
that the variation of initial TSS had a significant effect on the final TSS of the ginger
wines. The LSD test showed that the TSS of ginger wines made from the mashes having
initial TSS of 16o and 20oBrix were not significantly different (p<0.05). The TSS of the
ginger wine prepared from the mash having TSS of 24oBrix was significantly different
higher than those of the ginger wines prepared from the mashes of 16o and 20oBrix.
However, the variation of ginger amount had no significant effect on the final TSS of the
ginger wines (Appendix IV). Dhakal (2007) also reported that the same result in palm
wines.
o
o
54
4
5
6
7
8
9
10
11
10 12 14 16 18 20 22 24 26
Initial TSS of the mash
Alc
ohol
con
tent
of t
he g
inge
r w
ine,
%(v
/v) 1% (m/v) ginger
1.5% (m/v) ginger2% (m/v) ginger
Fig. 4.3 Effect of initial TSS on the alcohol content of the ginger wines.
4
5
6
7
8
9
10
11
0 0.5 1 1.5 2 2.5
Ginger amount, % (m/v)
Aco
hol c
onte
nt o
f the
gin
ger
win
e, %
(v/v
)
16 Brix TSS20 Brix TSS24 Brix TSS
Fig. 4.4 Effect of ginger amount on the alcohol content of the ginger wines.
The alcohol contents of the ginger wines made from the mashes having initial TSS of 16o,
20o and 24oBrix were found to be 6.87, 8.63 and 9.46 % (v/v) respectively. The ANOVA
result concluded that the variation of initial TSS had significant effect but ginger amount
had no significant effect on the alcohol content of the ginger wines (Appendix IV). The
LSD test showed that the ginger wines made from the mashes having TSS of 16o and
o
o
o
55
20oBrix and 16o and 24oBrix were significantly different but the ginger wines prepared
from the mashes of 20o and 24oBrix TSS were not significantly different in alcohol content.
Similarly, the alcohol content of the ginger wines made from the mashes having different
ginger amounts (1, 1.5 and 2 % m/v) were not significantly different.
4.1.2 Effect on sensory quality
0123456789
Smell Taste Color Mouth feel OverallSensory attributes
Mea
n sc
ore
16 Brix20 Brix24 Brix
4.5 Effect of initial TSS on the sensory properties of ginger wines.
012345678
Smell Taste Color Mouthfeel
Overall
Sensory attributes
Mea
n sc
ore
1% (m/v) ginger1.5% (m/v) ginger2% (m/v) ginger
4.6 Effect of ginger amount on the sensory properties of the ginger wines.
The average scores for smell of ginger wines made from the mashes having 16o, 20o and
24o Brix were found to be 6.41, 6.81 and 6.11 respectively. The ANOVA report indicated
o
o
o
56
that the variation of TSS of the mashes had significant effect (p<0.05) (Appendix V). The
smell of ginger wines made from the mashes of 16o and 20oBrix, 20o and 24oBrix, and 16o
and 24oBrix was significantly different each other.
The average scores for taste of ginger wines made from the mashes having 16o, 20o and
24o Brix were found to be 6.26, 6.41 and 5.78 respectively. The ginger wines made from
the mashes of 16o and 20oBrix were not different in taste. But the taste of the wines made
the mashes of 16o and 24oBrix and 20o and 24oBrix was significantly different.
The average scores for color of ginger wines made from the mashes having 16, 20 and 24
Brix were found to be 6.46, 7.18 and 5.96 respectively. The ginger wines prepared from the
mashes having TSS of 16o and 20oBrix were similar in color but the wines made from the
mashes having TSS of 16o and 24oBrix and 20o and 24oBrix were significantly differ in
color.
The average scores for mouth feel of ginger wines made from the mashes having 16o, 20o
and 24oBrix were found to be 5.87, 6.48 and 5.71 respectively. The ginger wines made
from the mashes containing TSS of 20o and 24oBrix and 16o and 24oBrix had same mouth
feel but the wines prepared from the mashes of 16o and 20oBrix had significantly different
mouth feel.
The average scores for overall acceptance of ginger wines made from the mashes having
16o, 20o and 24oBrix were found to be 6.27, 6.48 and 5.24 respectively. The overall
acceptance of the ginger wines prepared from the mashes with 16o and 20oBrix TSS was
same. But the wines made from the mashes with TSS of 16o and 24oBrix, TSS of 20o and
24oBrix were significantly different in overall acceptance.
The average scores for smell, taste, color, mouth feel and overall acceptance of ginger
wines made from the mashes having 1, 1.5 and 2g/L were found to be 6.56, 5.75, 6.13,
5.27and 6.27, 6.48, 6.54, 6.54, 6.48 and 6.38 and 6.54, 5.74, 6.14, 6.34 and 5.97
respectively.
The ANOVA report showed that the variation of ginger amount in the mashes had no
significant effect on sensory characteristics (smell, taste, color, mouth feel and overall
acceptance) of the ginger wines (p>0.05). However, the LSD test showed that there was
not significant different difference in smell of the ginger wines containing different ginger
amounts while the taste of the ginger wines having the ginger amounts 1 and 1.5% m/v was
significantly different. Similarly, the wines containing 1.5 and 2% m/v were also different
in taste. But the ginger wines having ginger amounts 1 and 2% m/v were not significantly
57
different in taste. There was not significant different difference in color of the ginger wines
containing different ginger amounts. The ginger wines made from the mashes having
ginger 1 and 1.5 % (m/v) and 1.5 and 2 % (m/v) were significantly different in mouth feel.
But the ginger wines made from the mashes containing 1 and 2% (m/v) were similar in
mouth feel. The LSD test indicated that the overall acceptance of the wines made from the
mashes containing 1 and 1.5% m/v ginger, 1 and 2% m/v ginger was not significantly
different but the wines made from the mash having 1.5 and 2% m/v ginger were
significantly different.
By the chemical and sensory analyses, the ginger wine made from the mash having
20oBrix TSS, 1% ginger (m/v) and 4.5pH was found to be the best among all prepared
ginger wines.
4.2 Effect of yeast culture on chemical and sensory properties
The ginger wines prepared from pre optimized composition of mash (20oBrix, 1% m/v
ginger and 4.5pH) by fermenting by true wine and baker’s yeasts were analyzed for
reducing sugar, acidities (total, fixed and volatile), esters, total aldehydes, alcohol content
and results are shown in Table 4.1. (Appendix VII)
Table 4.1 Chemical composition of the ginger wines.
Parameters Values*
Wine A Wine B
pH 4.1a (0.06) 4.2b (0.08)
TSS (oBrix) 5.80a (0.20) 6.20a (0.15)
Alcohol Content (%v/v) 7.80a (0.15) 8.71b (0.16)
Total Acidity (as g lactic acid/L alcohol) 7.56a (0.10) 7.92a (0.17)
Fixed Acidity (as g lactic acid/L alcohol) 5.4a (0.20) 5.88a (0.24)
Volatile Acidity (as g lactic acid/L alcohol) 2.16a (0.05) 2.04a (0.10)
Reducing sugar (g/L) 5a (0.2) 6b (0.21)
Esters (as mg ethyl acetate/L alcohol) 45.5a (3.23) 40.23a (4.36)
Total aldehydes (as acetaldehyde), mg/L alcohol 30.61a (4.0) 40.23a (4.36)
Note: * Values are the means of three determinations. Figures in the parenthesis are the
standard deviation. Means having same superscripts in a row are not significantly different
(p>0.05).
58
Wine A=fermented by true wine yeast.
Wine B=fermented by baker’s yeast.
4.2.1 pH
The average pH of the ginger wines fermented by true wine and baker’s yeasts were found
to be 4.1 and 4.2 respectively. t-test result indicated that the pH of ginger wines fermented
by true wine and baker’s yeasts were significantly different (p<0.05). Wine prepared by
true wine yeast had significantly higher pH than that of baker’s yeast. Dhakal (2007) found
that palm wine made from high pH had the high final pH while the TSS of mash had no
effect on the pH of the wines. He prepared palm wine having pH 3.23 from the mashes
having 20oBrix TSS and 4.5 pH. The prepared palm wine had low pH. The palm sap is
sensitive to spoilage microorganisms. It could be acidified before the initiation of desirable
fermentation by yeast culture.
4.2.2 TSS
The average TSS of ginger wines fermented by true wine and baker’s yeasts were found to
be 5.8 and 6.2 respectively. Statistical analysis indicated that the ginger wines were not
significantly different in TSS (p>0.05) (Appendix VII). Dhakal (2007) found that the
variation in TSS and pH had a significant effect on the final TSS of palm wine. The palm
wine made from mash having initial TSS of 20oBrix and pH of 4.5 had final TSS of 6.8 oBrix. According to Gautam (1992), apple wine prepared from the mash having TSS of
20oBrix and pH of 4.5 by using S. ellipsodeus and murcha had the final TSS of 5oBrix. He
reported that the wine with high initial TSS had high final TSS. These values of TSS were
similar to that of other wines. The TSS of the prepared ginger wines lies within the
reported range of TSS.
4.2.3 Alcohol content
The alcohol contents were found to be 7.8 and 8.71% (v/v) in the ginger wines fermented
by true wine and baker’s yeasts respectively. t-test indicated that ginger wines fermented
by true wine and baker’s yeasts were significantly different in alcohol content (Appendix
VIII). The alcohol in wines is formed as a result of utilization of carbohydrates present in
the mash for the growth and metabolic activities of yeast during fermentation (Patel, 1999).
In a suitable environment and substrate, the amount of alcohol produced depends upon the
59
amount of sugar present and the efficiency of the yeast in converting the sugar to alcohol.
The alcohol content varies from 5% up to 21% (v/v). Natural wines contain 8.5 to 16%
ethanol by volume (Boulton et al., 1997). The legal limits for alcohol vary markedly for
different countries and are usually related to the tax structure (Amerine et al., 1967).
Dhakal (1988) prepared banana and ginger wines containing 8.39% and 7.06% (v/v)
alcohol. Shakya (2002) reported 11% (v/v) alcohol in bael wine. Gubhaju (2006) prepared
Rhododendron wine having 11.03% (v/v) alcohol. According to Gvaladez (1936), the
alcohol yield varies from 47.87-48.12% of TSS of fermentation mash. The alcohol contents
of the ginger wines were within the range of other reported wines. The result showed that
baker’s yeast could produce more alcohol than that of true wine yeast. It could be due to
higher fermentation temperature (28 to 30oC) than that optimum fermentation temperature
required wine yeast (below 20oC). Baker’s yeast could tolerate higher temperature and
produce more alcohol than wine yeast.
4.2.4 Total acidity
The average total acidity of the ginger wines fermented by true wine and baker’s yeasts
were found to be 7.56 and 7.92 g/L (as lactic acid) respectively. t- test indicated that ginger
wines fermented by baker’s and true wine yeasts were not significantly different (p> 0.05)
in total acidity (Appendix VIII). It was found that baker’s yeast results higher total acidity
than that of ginger wine fermented by true wine yeast. Total acidities are important
constituents of wine not only for their acid taste but also because they protect the wine
from spoilage, maintain the color, and are themselves sometimes attacked by
microorganisms (Amerine et al., 1967). Dhakal (2007) prepared palm wines having
acidities 4.05 g/L as lactic acid from the mashes having 20oBrix TSS and 4.5 pH. Gubhaju
(2006) also prepared wines having similar results. According to Reed, (1987) the higher
amount of total acid of naturally fermenting wine may be due to the presence of significant
numbers of Kloeckera species. The calculated values of total acidities were higher than
other reported values. It could be caused by the growth of the spoilage micro-organisms in
the ginger wines. The growth of lactic acid bacteria could produce lactic acid and increased
total acidity.
4.2.5 Fixed acidity
The average fixed acidity of the ginger wines fermented by true wine and baker’s yeasts
were calculated to be 5.4 and 5.88 g/L (as lactic acid) respectively, but the values of the
60
ginger wines were not significantly different (Appendix VIII). Dhakal (2007) prepared
palm wine having acidities 2.96 g/L as lactic acid from the mashes having TSS of 20oBrix
and 4.5 pH. The calculated values of fixed acidities were higher than other reported values.
The growth of lactic acid bacteria could produce lactic acid and increased fixed acidity in
the ginger wines.
4.2.6 Volatile acidity
It was found that the amount of volatile acidities of the wines fermented by true wine and
baker’s yeasts were found to be 2.16 and 2.04 g/L (as lactic acid) respectively. Statistical
analysis result showed that the values were not significantly different (Appendix VIII). The
volatile acids are produced mainly during the initial stage of fermentation, and more is
formed in the presence of oxygen than in absence (Amerine et al., 1967). The
determination of volatile acidity as an indication of spoilage has become a part of the legal
requirements for wine standardization. The amounts of acetic acid produced during
alcoholic fermentation are small-usually less than 0.03 gm. per 100 ml. The volatile acidity
of a sound, newly fermented dry table wine may range from 0.2 to 0.4 g/L (Ribereau-
Gayon, 1961). Increase beyond this level, however, may signal microbial involvement and
potential spoilage. According to Egon et al., (1981) the volatile acidity of wines such as
Port, Sherry, Claret, Burgundy, Hock and Campagne were 0.05-0.10, 0.05-0.23, 0.09-0.15,
0.20-0.35, 0.05-0.15 and 0.03-0.20% (m/v) respectively. The calculated values of volatile
acidity were out of the range of all types of wines. It could be due to the activity of film
forming yeasts, and particularly of acetic acid bacteria and lactic acid in the ginger wines.
2.4.7 Reducing sugar
The average reducing sugar in ginger wines fermented by wine and baker’s yeast were
found to be 5 and 6 g/L as dextrose respectively. t-test indicated that ginger wines
fermented by baker’s and true wine yeasts were significantly different in reducing sugar
content in the ginger wines at p<0.05 (Appendix VIII). The amount of reducing sugar is
variable. Dry wine contains less than 0.12% sugar and sweet wine contains up to 7% sugar.
The amount of reducing sugar depends on the conditions for fermentation. The
consumption of sugar by yeast depends on the strain of the yeast. The results obtained
showed that wine yeast utilized more sugar than that by baker’s yeast.
61
4.2.8 Esters
The average values of esters in ginger wines fermented by true wine and baker’s yeasts
were 45.5 and 40.23 mg/L as acetaldehyde respectively. The values of esters were not
significantly different in ginger wines fermented by true wine and baker’s yeast (Appendix
VIII). Esters are an important part of odor of wines. Only ethyl acetate seems to be
important-below about 200 mg. per liter for a desirable odor but above this it appears to
give a spoiled character to the wine. Both neutral and acid esters are found in wine. The
total esters in various wines vary between about 200 and 400 mg. as ethyl acetate per liter
(Amerine et al., 1967). These values are lower than that of various wines. Esters are
formed mainly during ageing by the oxidation of higher alcohols. These lower values of
esters in the ginger wines could be due to lack of ageing as the ginger wines were not aged.
4.2.9 Total aldehydes
The average total aldehydes as acetaldehyde in ginger wines fermented by true wine and
baker’s yeasts were found to be 30.61 and 23.16 mg/L as acetaldehyde respectively. t-test
result indicated that the wines fermented by true wine and baker’s yeasts were not
significantly different (p>0.05) (Appendix VIII).Acetaldehyde is a normal by-product of
alcoholic fermentation. The amount of aldehydes ranges from 200 to 500 mg/L as
acetaldehyde in various wines (Amerine et al., 1967). The amounts found in newly-
fermented wines are below about 75 mg per liter. These values are within the range.
4.3 Sensory Evaluation
The sensory evaluation of ginger wines was done by semi trained panelists including
teachers, research students, and staff of CCT, Dharan. The parameters selected for sensory
evaluation were smell, taste, color, mouth feel and overall acceptance. The data was
analyzed by t-test at p=0.05 (Appendix IX).
62
0123456789
10
Smell Taste Mouth feel Color OverallacceptanceSensory attributes
Mea
n Sc
ores Fermented by wine yeast"
Fermented by baker's yeast"
Fig. 4.7 Effect of yeast type on the sensory properties of ginger wines fermented by true
wine and baker’s yeasts.
4.3.1 Smell
The average score for smell were found to be 8.1 and 6.9 for ginger wines fermented by
true wine and baker’s yeasts respectively. Statistical analysis showed that the smell of
ginger wine made by fermenting with true wine yeast was superior to that made by
fermenting with baker’s yeast (Appendix IX). Baker’s yeast could tolerate higher
temperature and consumed sugar faster. The fermenting yeast settled down at the bottom.
The ginger wine fermented by baker’s yeast came in contact with yeast cells and gained
yeasty flavor. So, ginger wine made by using true wine yeast was superior to that made by
using baker’s yeast at the provided conditions.
4.3.2 Taste
The average taste scores were found to be 7.2 and 7.5 respectively. The taste is combined
effect of oBrix and acidity. The t-test on the data on taste showed that there was no
significance difference between ginger wines fermented by true wine and baker’s yeasts.
These ginger wines did not differ each other at p<0.05 (Appendix IX).
4.3.3 Mouth feel
The average scores of ginger wines fermented by true wine and baker’s yeasts were found
to be 7.8 and 6.8 respectively. t-test of the data on mouth feel showed that there was not
significant difference between these ginger wines at p<0.05 (Appendix IX). The mouth feel
63
score of ginger wine fermented by true wine yeast was higher than that of ginger wine
fermented by baker’s yeast (Table 4.1). It could be due to higher sugar and alcohol content
in the ginger wine fermented by baker’s yeast.
4.3.4 Color
The average scores were found to be 7.8 and 6.8 for ginger wines fermented by true wine
and baker’s yeasts respectively. The t-test on the data on color showed that there was
significant difference between ginger wines fermented by true wine and baker’s yeasts at
p<0.05 (Appendix IX). The color score of ginger wine A higher than that of ginger wine B
(Table 4.1).
4.3.5 Overall acceptance
The average scores for overall acceptance were found to be 7.6 and 7.2 for ginger wines
fermented by true wine and baker’s yeasts respectively. The t-test showed that there was
significance difference between ginger wines at p<0.05 (Appendix IX). The overall score
of ginger wine fermented by true wine yeast is higher than that of ginger wine fermented
by baker’s yeast (Appendix VI).
4.4 Effect of bentonite on the clarification of ginger wine.
Bentonite was used for the clarification of the ginger wines at the rates of 0.5, 1 and 1.5
g/L. The average values of turbidities were found to be 16.52, 17.01, 17.81 and 526 FTU
for the ginger wines clarified by bentonite at the rate of 0, 0.5, 1.0 and 1.5 g/L respectively.
The ANOVA result showed that there was significant different on the clarity of ginger
wines by the use of bentonite in different concentrations (0.5, 1 and 1.5 g/L) at p<0.05. But
the ginger wines clarified by bentonite at the rate of 0.5, 1 and 1.5 g/L were not
significantly different each other. The turbidity of the ginger wine, which was clarified by
bentonite at the rate of 0.5g/L, was found to be the least (Fig. 4.8).
64
0
100
200
300
400
500
600
0 0.5 1 1.5
Bentonite concentration (g/L)
Turb
idity
(FTU
)
Fig. 4.8 Effect of bentonite on the clarification of ginger wine.
The result showed that the use of bentonite at the rate of 0.5 g/L was effective for the
clarification of the ginger wines. According to Boulton et al., 1997, the recommended
amount of bentonite for white table wine is 0.12 to 0.72 g/L (Table 2.4). In the experiment,
the effective amount of bentonite was found to be 0.5g/L for the prepared ginger wines.
The amount of bentonite for the clarification of wines depends on the pH. The amount of
bentonite for the clarification of the ginger wine was within the prescribed amount.
Part V
Conclusion and recommendation
On the basis of the results and discussion, the following conclusions were drawn:
5.1 Conclusions
1. The ginger wine could be prepared from the mash having 10% raisin, 20oBrix TSS, 1%
ginger (m/v) and 4.5pH by using baker’s yeast as comparable quality of the ginger
wine fermented by true wine yeast in the provided conditions.
2. Bentonite was found to be most effective at the rate of 0.5g/L for the clarification of
ginger wine.
5.2 Recommendations
1. The clarifying effects of different fining agents other than bentonite can be studied in
ginger wine.
2. Study on anti-microbial effects of ginger can be done.
3. Study on the physicochemical changes during its ageing can be carried out.
4. Study on the flavor profiles of the ginger wines can be carried out.
Part VI
Summary
The term “wine’’ used alone generally refers to the fermented product made from grape
juice and the wines made from fermented mashes of other fruits are commonly identified
by the specific fruit names such as pineapple wine, pumpkin wine etc. In the same way,
wine made by using spice to flavor and to add some nutritional values, the wine is also
named by the name of the spice used such as ginger wine.
In this study, the ginger was bought from local market of Dharan which was cultivated in
Bhojpur district, baker’s yeast was bought from Gorkha Department Store, Itahari-1, which
was manufactured in Belgium and true wine yeast was collected from Makalu Wine
Industries (P.) Ltd., Basantapur, Tehrathum. First, mashes having different sugar
concentrations (16o, 20o and 24oBrix) and ginger amounts (1, 1.5 and 2% m/v) were
fermented by baker’s yeast at the rate 1 g/L at room temperature. After completion of
fermentation, final TSS and alcohol content were determined. The ginger wines thus
prepared were analyzed for both chemical and sensory properties. The data obtained was
analyzed and interpreted statistically by ANOVA at p<0.05. The initial TSS of the mash
had a significant effect but ginger amount had no significant effect on the chemical and
sensory properties. The ginger wine made from the mash having TSS of 20oBrix, 4.5pH
and ginger amount 1% m/v was found to be superior to other wines.
The mashes having TSS of 20oBrix, 4.5pH and ginger amount 1% m/v were made,
inoculated with true wine and baker’s yeasts at the rate of 1gm. per liter separately and left
for fermentation. After completion of fermentation, they were clarified by using bentonite
suspension (5% m/v) at the rates of 0.5, 1 and 1.5 g/L. The use of bentonite had a
significant effect on the clarification of the ginger wines. The bentonite at the rate of 0.5
g/L was found to the most effective for the clarification of the ginger wines. The ginger
wines were analyzed for chemical properties (pH, TSS, alcohol content, total acidity, fixed
acidity, volatile acidity, reducing sugar, esters and total aldehydes). The pH, TSS, and
alcohol content of the ginger wines A and B were 4.1 pH, 5.8oBrix, 7.8% (v/v) and 4.2 pH,
6.2oBrix, 8.71 respectively. The total, fixed and volatile acidities (as g lactic acid) of the
ginger wines fermented by true wine and baker’s yeasts were 7.56, 5.4, 2.16 and 7.92 g,
67
5.88, 2.04 g/L respectively. The reducing sugar of the ginger wines were 5 and 6 g/L
respectively.
Similarly, the esters and total aldehydes of the ginger wines fermented by true wine and
baker’s yeasts were 45.5, 30.61 and 40.23, 23.16 mg/L alcohol respectively.
There was significant difference in the pH, alcohol content and reducing sugar between
them by t-test at p<0.05. TSS, total acidity, fixed acidity, volatile acidity, esters and total
aldehydes were not significantly different by t-test.
The prepared ginger wines were subjected for sensory evaluation (smell, taste, mouth
feel and overall acceptance). These ginger wines were not significantly different in taste
and mouth feel but they were significantly different in smell, color and overall acceptance
by t-test at p<0.05.
The ginger wine could be prepared from the mash having 10% raisin, 20oBrix TSS, 1%
ginger (m/v) and 4.5pH by using baker’s yeast as comparable quality of the ginger wine
fermented by true wine yeast in the provided conditions. Bentonite was found to be most
effective at the rate of 0.5g/L for the clarification of ginger wine.
References
Alan, H.V. and Jane, P.S. (1994). Beverage Technology, Chemistry and Microbiology
Chapman and Hall.
Amerine, M.A., Berg, H.W., and Cruess, W.V. (1980). The Technology of Wine Making.
The AVI publishing Co., INC., Westport, Connecticut.
Andrew, S. (1980). The Food Beverage Service, Tata McGraw Hill Publishing Co. Ltd.,
New Dehli.
Anon. (1975). The Brandy Market of The World. Rep. Cent. Fr. Commer. Exter. In Wine
and Brandy. Presott and Dunn’s Industrial Microbiology, G. Reed (Ed), 1987. CBS
Publisher and Distributer. New Dehli.
AOAC. (2005). Official Method of Analysis, Association of Official Analytical Chemists,
Washington DC.
Austin, C. (1968). The Science of Wine Making, University of London Press Ltd.
Battcock, M. and Azam-Ali, S. (1998). Fermented Foods and Vegetables, A global
Perspective; FAO Agriculture service Bullletine 134; Italy.
Benda, I. (1987). Wine and Brandy. In Prescott and Dunn’s Industrial Microbiology, G.
Reed (Ed), 1987. CBS Publisher and Distributer. P.293-380.
Berry, D.R. and Watson, D.C. (1987). Production of Organoleptic Compounds. In: “ Yeast
Biotechnology’’ D.R., Berry, I. Russel and G.G. Stewart eds. Elsevier Applied science
publishers, London and Newyork.
Bhagat, B.K. (1989). Wine making and its maderization from Jack-Fruit and Pineapple. B.
Tech. (Food) Dissertation, CCT, TU, Nepal.
Birch, G.G. and Lindley, M.G. (1985). Alcoholic Beverage, Elsevier Applied Science
Publishers, London.
Boulton, R.B. (1998). Principles and Practices of Wine Making, An Aspen Publication,
Maryland, US.pp, 455-465
Campbell-Plant, G. (1980). Fermented Food of The World, A dictionary and guide.p. 150,
Butter worths, London.
Connel, D.W. (1970). The Chemistry of essential oil and oleoresin of ginger (Zingiber
officinale Rosc.) Fla. Ind. 1(10): 677-693.
69
Desrosier, N.W. and Desrosier, J.N. (1978). The Technology of Food Preservation, 4th
edn., CBS Publishers and Distributers, New Dehli, India.
Dittrich, H.H., (1977). Microbiology of Wines. In Wine and Brandy. Prescott and Dunn’s
Industrial Microbiology, G. Reed (Ed), 1987. CBS Publisher and Distributer.
Douglas, M. and Considine, P.E. (1982). Food and Food Production Encyclopedia, Van
Nostrand, Reinhold Company, Inc., New York, N.Y. 10020.
Egan, H., Kirk, R. S. and Sawyer, R. (1981). Pearson’s Chemical Analysis of Foods.
Churchill Livingstone. pp. 353-364.
Govindrajan, V.S. (1982). Ginger Chemistry, Technology and Quality Evaluation CRC.
Crit. Review of Food Sci. and Nutrition Part II; pp..189-258.
Graham, W.O. (1940 a, b, c). The Influence of Distillation Method on Brandy
Composition. Australian Brewing and Wine Journal 58 (6), 40-42. In Alcohol
recovery. Yeast biotechnology. D.E. Berry, I. Russell and G.G. Stewart (Eds), 1987.
Allen and Unwin. p. 505.
Gubhaju, M., (2006). Preparation and quality evaluation of wine prepared from
Rhododenron flower. Dissertation, B. Tech. (Food), Central Campus of Technology,
Tribhuwan University, Nepal.
Guymon, J.F., Ingraham, J.L. and Crowell, E.A. (1961). In: “The Technology of Wine
Making” by Amerine et. al.,(2nd edn),p203, The AVI Pub. Co. Ltd.(1967).
Guymon, J.F. and Crowell E.A. (1969). American Journal of Journal of Enology and
Viticucltur 20, 76. In Pearson’s Chemical Analysis of Foods, H. Egan, R.S. Kirk and R.
Sawyer(Edss), 1981.
Gvaladze, V. (1936). Relation Between the Products in alcoholic Fermentation. Lennin.
Agr. Acad. USSR, Moscow. Chemistry of Fermentation and Composition of Wines. In
The technology of wine making, M.A. Amerine, H.W. Berg, and W.V. Cruess (Eds),
1967. The AVI publishing Co. Inc. p. 180.
Haard, N.F. (1999). Cereals: Rationale for Fermentation. In: Fermentated Cereals, a Global
Perspective. FAO Agriculture Services Bulletin no. 138 (e-book)
www.austwine.com/
http/www.austwine/0089a/rm.html
http://www. Byronwines.com/iw_facilities.asp
http://www.ehow.com/facts_4924826_health-benefits-ginger.html
http.//www.metalimagination.com/historyofwine.html
70
http.//www.metalimagination.com/winemaking.html
http.//www.statemaster.com/encyclopedia/Ginger-wine
http://en.wikipedia.org/wiki/Alcoholic-beverage.
Johnson, A.H. and Peterson, M.S. (1974). Encyclopedia of Food Technology, The AVI
Pub. Co., INC., Westport, Connecticut.
Jones, K.C. (1985). Adoption of Fermentative Organisms to Alcoholic Environments. In:
“Alcoholic Beverages” G.G. Birch and M.G. Lindley (Eds). Elsevier Appliedn Sc.
Publication, p171
Karki, D.B. and Karki, R.J. (2001). Preparation and Quality Evaluation of Orange
(Mandarin) Brandy. Dissertation, B. Tech. (Food), Central Campus of Technology,
Tribhuwan University, Nepal.
Kenneth, C.F. (1997). Wine Microbiology. Chapman and Hall. P. 137-140.
Koch, J. (1953). Formation of Lactic Acid in Sweet must During Storage in tanks Under
CO2 Pressure .Z. Lebensm.-Unters.-Froch. 97, 17-24. In Wine and Brandy. Prescott
and Dunn’s Industrial Microbiology, G. Reed (Ed), 1987. CBS Publisher and
Distributer. P.302.
K.C., J. B., B.K., Subba, D. K. and Ghimire, G. (2004). Praticals in Basic biochemistry and
Industrial Microbiology. Publ. Maya K.C., Kathmandu, Nepal.
Lafon, M. (1995). The Formation of Secondary Products of the Alcoholic Fermentation.
Sci. thesis. Univ. Bordeaux. In Wine and Brandy. Prescott and Dunn’s Industrial
Microbiology, G. Reed (Ed), 1987. CBS Publisher and Distributer.p. 379.
Lal, G., Siddapa, G.S. and Tondon, G.L., (1986).Preservation of Fruits and Vegetables.
Publications and Information division, Indian council of agriculture research. pp. 97-
99, 113-115.
Leverington, R.E. (1975). Ginger Technology; Food Tech. Aust. 27 (8), pp. 309-313.
Lewis, Y.S. (1984). Spices and Herbs for Food Industry; Food Trade Press; pp. 62.
Lucia, (1954). In: “Food and Food Production Encyclopedia” by Doulas et al., p 2149, Van
Nostrand Reinhold Company, INC., New York, N.Y. 10020 (1982).
Manay N.S. and Shadashaswaswany, M. (1987). Food Facts and Principals, Wiley, Eastern
limilted. Mmegwa S.V.A. (1987). Factors controlling organoleptic properties in palm
wine fermentation. Ph. D. Thesis, Univ. Nigeria, Nsukka.
71
Mangalakumari, C.K., Nihan, C.A. and Mathew, A.G. Histochemical studies on
localization of significant constituents of Ginger; Indian Spices: 21(4), 22(1), 1984/85,
pp.15, 17, 19.
Morgan et al., In “Food and Food Production Encyclopedia” by Douglas et al., p 2149,
Van Nostrand Reinhold.
Nair, P.C.S. Agronomy of ginger and turmeric; in National Seminar on ginger and
turmeric; Status paper and abstracts; Central Plantation Crops Research Institute;
Regional Station; Calicut, April; 1980.
Odunfa S.A. (1985). African fermented foods. In Microbiology of Fermented Foods, Vol. 2
(B.J.B. Wood, ed.) pp. 155-191, Elsevier Applied Science, London.
Okafor, N. (1978). Microbiology and Chemistry of Oil Palm-Wine. Advance Applied
Microbiology. Academic Press, London 24, 273-256.
Oli, P. (1999). Study on the temperature optimization for multistage drying and bleaching
effect in the production of dried ginger. B.Tech. (Food) Dissertation, TU, CCT,
Hattisar, Dharan, Nepal.
Osterwalder, A. (1934). Cold Fermentations and Cold Fermentation , London 24, 273-256.
Osterwalder, A. (1934). Cold Fermentations and Cold Fermentation Yeasts. Zentralbl.
Bakteriol. Parasitenkd. Infektionkr. Hyg. Abt. 2 90,226-249. In Wine and Brandy.
Prescott and Dunn’s Industrial Microbiology, G. Reed (Ed), 1987. CBS Publisher and
Distributer . p.299
Pederson, C.S. (1971). Microbiology of Food Fermentation, The AVI Publishing Co. Inc.
pp133-161.
Peynand and Gumiberteau, (1962). The Formation of Higher Alcohol By Wine Yeast. Ann.
Techno. Agric. 11 pp 85-105. In “Wine and Brandy” Prescott and Dunn’s Industrial
Microbiology (1987. CBS Pub. and Dist. P300.
Prescott, S.C. and Dunn, C.G. (1987). Industrial Microbiology, 3rd edn. McGraw-Hill
Book Co., New York.,
Rai, B. (2002). Industrial Microbiology, CCT, Hattisar, Dharan; Nepal.
Rai, R.K. (1984). To study Rakshi (Distilled Liquor) Making Process in Eastern Nepal. B.
Tech. (Food) Dissertation. Tribhuwan University, Nepal.
Ranganna, S. (2001). Handbook of Analysis and Quality Control for Fruits and Vegetable
Products. Tata McGraw-Hill Publishing Co. Ltd.
72
RCAPS (1974). Research Commetee on Analysis of Potable Spirits, Journal of Association
of Public Analysis. In Pearson’s Chemical Analysis of Foods, H. Egan, R.S. Kirk and
R. Sawyer (Eds), 1981.
Regmi, P.R. (1980). An Introduction to Enumeration of Nepalese Foods Plants.
Rouniyar, R.K. (1994). Studies on Fermentation Pattern and Preservation Techniques of
palm sap. B. Tech. (Food), Dissertation, CCT, TU, Nepal.
Saller, W. (1955). Improvement in the Quality of Wines and Sweet Musts by Cooling.
Sigurd Horn-Verlag, Frankfurt. In Wine and Brandy. Prescott and Dunn’s Industrial
Microbiology, G. Reed (Ed), 1987. CBS Publisher and Distributer. p.379.
Schreier, P. (1979). Flavor Composition of Wines, a review. CRC Crit. Rev. Food Sci.
Nutr. 12, 59-111. In Uzochuwu et al., (1996). Volatiles of palm wine using solvent
Extract. Journal of Food Quality; Food and Nutrition Press, Inc., Trumbull,
Connecticut. 20(1997) 483-494.
Shakya, A. (2002). Preparation and Quality Evaluation of Beal wine (Aegle marmelos)
wine. B.Tech. (Food), Dissertation, CCT, Hattisar, Dharan,Nepal.
Sharma, B.P. (1967). Ginger Production Technology (A text in Nepali); published by
GRP/NARC; pp.1-9, 14-16.
Sharpnel, G.S. (1967). The technological development of the Green Ginger Industries in
Australia; Fd.
Sills, V.E. (1961). Processing and marketing of ginger products; South Pacific Bulletin;
South Pacific Commission Noumea; 11(3): 58-61.
Subba, C., Rai, B.K., Limbu, K.P. and Maden, K. (2005). Indigenous Foods of Limbus of
Dhankuta, Tehrathum and Dharan. Project report submitted to National Foundation for
Uplift of Adivasis/Janajati, Nepal.
Tannanhill, R. (1973). Alcoholic beverage. In; “Food and Beverage Mycology” (L. R.
Beuchat ed.). The AVI Publishing Co. Inc. Westport, Connecticut.
The Encyclopedia Britannica, 2007. Alcoholic Beverages.
The Wealth of India (1969). Phoenix Vol. 8, 17-28, published by the information
directorate of Council of scientific and Industrial Research, New Dehli, India.
Thompson, E.H., Wolf, I.D. and Allen, E.C. (1987). Ginger rhizome; A new source of
proleolytic enzyme: J.F.S.T., 38; 625-655.
Varnam, A.H. and Sutherland, J.P. (1994). Beverages, 1st edn., Chapman and Hall,
London,UK. pp642-656.
73
Veera Raj Urs., M. (1978). In Symposium on Alcoholic beverage industries in India. Dehli:
17-19.
Wikipedia, The free encyclopedia, Alcoholic beverage, Jan. 12, 2007.
Whiley, A.W. (1974). Ginger growing in Queeensland; Qld. Agric. J; 100(11); pp. 551.
White, J. and Munns, D.J.J. (19510. Influence of Temperature on Yeast Growth and
Fermentation. Influence of temperature on yeast growth and fermentation. J. Inst.
Brew. 57, 280-284. In: Wine and Brandy. Prescott and Dunn’s Industrial Microbiology,
G. Reed (Ed), 1987. CBS Publisher and Distributer.p. 379.
Zoecklein, W.B., Fugelsang, C.K., Gump, H.B. and Nury, S.F. (1997). Wine analysis and
production. CBS Publ. and Dist. P.
Appendices
Appendix I
Table A.1 TSS reduction during fermentation of mashes.
Days from pitchingTSS
Mash A Mash B
5 days 8 9.5
6 days 7.5 8.5
7 days 7 7.5
8 days 6.5 7
9 days 6 6.5
10 days 5.8 6.2
11 days 5.8 6.2
Appendix II
Table A.2 Data obtained from analysis of samples of wines.
Parameters Values*
Wine A Wine B
pH 4.1a (0.06) 4.2b (0.076)
TSS (oBrix) 5.80a (0.2) 6.20a (0.153)
Alcohol Content (%v/v) 7.80a (0.150) 8.71b (0.160)
Total Acidity (as gm lactic acid/L alcohol) 7.56a (0.104) 7.92a (0.166)
Fixed Acidity (as gm lactic acid/L alcohol) 5.4a (0.200) 5.88a (0.239)
Volatile Acidity (as gm lactic acid/L alcohol) 2.16a (0.051) 2.04a (0.104)
Reducing sugar (g/L) 5a (0.2) 6b (0.208)
Esters (as mg ethyl acetate/L alcohol) 45.5a (3.229) 40.23a (4.364)
Total aldehydes (as acetaldehyde), mg/L alcohol 30.61a (3.992) 23.16a (1.967)
Note: * Values are the means of three determinations.
Wine A=fermented by true wine yeast
Wine B=fermented by baker’s yeast
75
Appendix III
Table A.3 Specimen cards for sensory evaluation by hedonic rating
Hedonic Rating Test
Name:
Date:
Product: Ginger Wine
Please taste the samples (wines fermented by baker’s yeast and wine yeast separately) and
taste how much you like or dislike. Use the appropriate scale to show your attitude by
giving the point that best describe your feeling about the sample.
Give points as follows:
Like extremely 9
Like very much 8
Like moderately 7
Like slightly 6
Neither Like nor dislike 5
Dislike slightly 4
Dislike moderately 3
Dislike very much 2
Dislike extremely 1
Parameters Scores of samples
A B
Smell
Taste
Color
Mouth feel
Overall acceptance
Comment if any:
76
Appendix IV
Table A.4 ANOVA table for the chemical properties (TSS and alcohol content) of the
ginger wines fermented by baker’s yeast.
Variate: TSS
Source of variation d.f. s.s m.s. v.r. F pr.
Initial TSS 2 127.527 63.7639 255 <0.001
Ginger amount, % m/v 2 0.3611 0.1866 0.72 0.512
Ginger amount, % m/v× Initial TSS 4 6.4722 1.6181 6.47 0.010
Residual 9 2.2500 0.2500
Total 27 136.6111
Variate: Alcohol content
Source of variation d.f. s.s m.s. v.r. F pr.
Initial TSS 2 21.623 10.81159 128.11 <0.001
Ginger amount, % m/v 2 0.01034 0.00517 0.06 0.941
Ginger amount, % m/v× Initial TSS 4 1.04858 0.26215 3.11 0.073
Residual 9 0.75954 0.08439
Total 17 23.44164
77
Appendix V
Table A.5 ANOVA table for sensory characteristics of ginger wines fermented by baker’s
yeast.
Variate: Smell
Source of variation d.f. s.s m.s. v.r. F pr.
Ginger amount, % m/v 2 0.296 0.148 0.14 0.871
Initial TSS 2 6.741 3.370 3.14 0.049
Ginger amount, % m/v× Initial TSS 4 5.630 3.14 1.31 0.274
Residual 72 77.333 1.074
Total 80 90.000
Variate: Taste
Source of variation d.f. s.s m.s. v.r. F pr.
Ginger amount, % m/v 2 4.519 2.259 1.30 0.278
Initial TSS 2 5.852 2.926 1.69 0.192
Ginger amount, % m/v× Initial TSS 4 14.963 3.741 2.16 0.083
Residual 72 124.889 1.735
Total 80 150.222
Variate: Mouth feel
Source of variation d.f. s.s m.s. v.r. F pr.
Ginger amount, % m/v 2 8.617 4.369 3.04 0.054
Initial TSS 2 1.506 0.753 0.53 0.590
Ginger amount, % m/v× Initial TSS 4 5.679 1.420 1.00 0.412
Residual 72 102.000 1.417
Total 80 117.802
78
Variate: Color
Source of variation d.f. s.s m.s. v.r. F pr.
Ginger amount, % m/v 2 9.5840 5.2920 3.46 0.066
Initial TSS 2 1.54420 0.7210 0.65 0.67
Ginger amount, % m/v× Initial TSS 4 5.25640 1.5410 1.34 0.617
Residual 72 102.230 1.523
Total 80 2.85900
Variate: Overall acceptance
Source of variation d.f. s.s m.s. v.r. F pr.
Ginger amount, % m/v 2 2.691 1.346 1.01 0.368
Initial TSS 2 7.802 3.901 2.94 0.059
Ginger amount, % m/v× Initial TSS 4 2.864 0.716 0.54 0.707
Residual 72 95.556 1.327
Total 80 108.914
Appendix VI
Table A.6 Sensory evaluation scores of the wine samples.
Parameters
Panelists
1 2 3 4 5 6 7 8 9 10
A B A B A B A B A B A B A B A B A B A B
Smell 9 8 8 6 8 7 8 7 9 8 8 6 8 7 7 6 8 7 8 7
Taste 8 8 7 8 7 8 7 8 8 8 7 6 7 8 7 8 7 8 7 6
Mouth Feel 8 7 7 8 7 6 8 8 8 7 7 7 7 6 7 6 8 8 8 7
Color 8 8 8 6 8 7 8 7 8 7 7 6 8 7 7 6 8 7 7 8
Overall acceptance 8 7 7 8 8 7 8 8 8 8 7 6 8 7 7 6 8 7 8 7
Note: In Table A= Wine fermented by baker’s yeast
B= Wine fermented by wine Yeast
79
Appendix VII
Table A.7 Chemical composition of the ginger wines fermented by true wine and baker’s
yeasts.
Parameters Values*
Wine A Wine B
pH 4.1a (0.06) 4.2b (0.08)
TSS (oBrix) 5.80a (0.20) 6.20a (0.15)
Alcohol Content (%v/v) 7.80a (0.15) 8.71b (0.16)
Total Acidity (as g lactic acid/L alcohol) 7.56a (0.10) 7.92a (0.17)
Fixed Acidity (as g lactic acid/L alcohol) 5.4a (0.20) 5.88a (0.24)
Volatile Acidity (as g lactic acid/L alcohol) 2.16a (0.05) 2.04a (0.10)
Reducing sugar (g/L) 5a (0.2) 6b (0.21)
Esters (as mg ethyl acetate/L alcohol) 45.5a (3.23) 40.23a (4.36)
Total aldehydes (as acetaldehyde), mg/L alcohol 30.61a (4.0) 40.23a (4.36)
Appendix VIII
Table A.8 t-test table for chemical properties of the ginger wines.
Parameters Mean Variance
df tcal. ttab. A B A B
pH 4.1333 4.3166 0.0033 0.0058 4 3.316 2.7764
TSS 5.8 6.1667 0.04 0.0233 4 2.524 2.7764
Alcohol 7.7933 8.7067 0.0226 0.0256 4 7.201 2.7764
Total acidity 6.2667 6.5967 0.0108 0.0277 3 2.910 3.1824
Fixed acidity 4.54331 4.8867 0.0401 0.0443 4 2.045 2.7764
Volatile acidity 1.80667 1.7333 0.0026 0.0108 3 1.094 3.1824
Reducing sugar 5.1 6.0333 0.04 0.0433 4 5.6 2.7764
Esters 45.5367 40.23 10.428 19.047 4 1.693 2.7764
Total aldehydes 30.7667 23.163 15.936 3.8682 3 2.959 3.1824
80
Appendix IX
Table A.9 t-test table for sensory properties of the ginger wines.
Parameters Mean Variance
tcal. ttab. A B A B
Smell 8.1 6.9 0.3222 0.5444 17 4.076 2.110
Taste 7.2 7.6 0.1778 0.4889 15 1.549 2.131
Mouth feel 7.5 7 0.2778 0.6667 15 1.627 2.131
Color 7.7 6.9 0.2333 0.5444 16 2.868 2.112
Overall acceptance 7.7 7.1 0.2333 0.5444 16 2.151 2.112
Appendix X
Table A.10 ANOVA table for turbidities of ginger wines.
Source of variation d.f. s.s m.s. v.r. F pr.
Replicate 2 0.05840 0.02920 0.46 0.663
Amount of bentonite 2 2.54420 1.27210 19.85 0.008
Residual 4 0.25640 0.06410
Total 8 2.85900
81
Appendix XI
Table A.11 Effect of bentonite on the clarification of ginger wine.
Bentonite concentration Turbidity (FTU)
0.0 g/L 526
0.5 g/L 16.52
1.0 g/L 17.01
1.5 g/L 17.81
Appendix XII
Table A.12 Average chemical analysis of prize-winning high quality wines.
Component
(g per 100 ml)
Dry
White
Dry Red Sweet White Sweet Red Sparkling
Alcohol by volume, (%) 2.45 12.61 18.38 19.30 13.22
Alcohol 9.88 10 14.58 10.48
Glycerol 0.7019 0.6355 0.3025 0.5089 0.4177
Ash 0.196 0.247 0.203 0.311 0.153
Total acids 0.586 0.649 0.412 0.502 0.658
Volatile acids 0.101 0.128 0.092 0.122 0.082
Reducing sugars 0.134 0.146 11.30 10.20 3.409
Protein 0.162 0.150 0.162 0.232 0.214
Tannins 0.039 0.236 0.036 0.096 0.035
Specific gravity 0.9917 0.9947 1.0298 1.0276 1.0045
Source: Amerine et al., 1972
82
Appendix XIII
Table A.13 Major wine producing countries of the world-1996.
Countries
Wine
production
(million L)
Wine
exports
(million L)
Wine
consumption
(million L)
Total
grape’000
Ton
Area of
vines’000
Hectare
France 5965 1229 3479 7701 917
Italy 5877 1511.5 3562 9459 922
Spain 3267 672.9 1475 4846 1224
USA 1864 163.8 2046 4935 311
Argentina 1268 125.4 1355 2040 211
S. Africa 1000 99.6 406 1440 106
Portugal 953 200 580 1270 259
Germany 830 300.8 1866 1297 105
Romania 766 46.7 725 1427 256
Australia 678 147.1 329 1086 81
Others 4785 1241.6 6499 23180 3350
World
total
27253 5738.4 22322 58681 7742
(Source: Anon, 1996)
83
Appendix XIV
Table A.14 Composition of some wines.
Parameters Port Sherry Claret Burgundy Champagne
Specific gravity 0.995-
1.050
0.992-
1.015
0.990-
1.001
0.995-
1.001
1.040-1.055
Alcohol (gm/100ml) 13.5-20.0 13.5-20.5 7.5-12.5 7.5-12.5 10.0-14.0
% Total solid 3.3-13.0 2.0-9.6 2.0-3.5 2.0-3.5 9.5-18.0
% Free volatile acid (as
acetic acid)
0.05-0.10 0.15-0.23 0.09-0.15 0.2-0.35 0.03-0.20
% Fixed acid (as acetic
acid)
0.35-0.55 0.25-0.50 0.30-0.50 0.3-0.60 0.30-0.45
% Ash 0.25-0.35 0.35-0.55 0.2-0.3 0.2-0.4 0.25-0.45
% Sugars 2.5-12.0 2.0-7.0 0.0-0.7 0.03-0.55 8.5-16.0
(Source: Pearson, 1981)