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Food Preservation ( MT 203)
Iman_Jan2011
MT 203 FOOD PRESERVATION
LABORATORY MANUAL
Food Technology Department Politeknik Sultan Haji Ahmad Shah
Food Preservation ( MT 203)
Iman_Jan2011
Lab : 1 Title : Equipments Used In Processing Laboratory Objectives : At the end of the lab, students must be able to:
1) know the functions of specific equipments used in processing
laboratory.
2) operate the specific equipments.
Introduction : Food preservation is defined as any purposeful treatment or
processing of food which extends the keeping quality of raw material to a
period longer than its natural keeping quality. The processes involved in
protecting food against microbes and other spoilage agents to permit its
future consumption. The preserved food should retain a palatable
appearance, flavour, and texture, as well as its original nutritional value.
Preservation can be arbitrarily divided between temporary, a short term
preservation to keep product fresh while distributing to markets and
permanent, a longer term where products can remain in consumers
homes indefinitely until use
Materials and Equipment : Refractometer Fruit juice pH meter Rice Vernier caliper Can Micrometer Method :
1) Measure the sweetness of the fruit juice using refractometer.
Take the value of Brix.
2) Measure the pH value of the fruit juice using pH meter.
Take the pH value.
3) Using micrometer, measure the size of a rice( length, thickness).
4) Using vernier calliper, measure the size of a can ( diameter,
thickness, depth).
Food Preservation ( MT 203)
Iman_Jan2011
Result :
1
2
3
4
5
6
average
Fruit Juice
Brix
pH value
Rice
Length
Thickness
Can
Thickness
Diameter
Depth
Discussion :
1) Specifically discuss the function and the manual procedure of each
equipments.
2) Discuss the advantages and the disadvantages of each equipments.
Conclusion : References :
Food Preservation ( MT 203)
Iman_Jan2011
Lab : 2 Title : Fruits Canning Objectives : At the end of the lab, students must be able to:
1) operate fruits canning operation according to the right methods.
2) compare and determine the organoleptic values of canned fruits.
Introduction : Canning is a process of preserving food by heating and sealing it
in airtight containers. It is one of the easiest and fastest preservation
method which using thermal process. Heating destroys enzymes and
microorganisms. The sealing of can ensure no microorganisms and
oxygen can get in. Airtight containers make sure that no oxygen in the
containers for bacteria to live and chemical changes. The thermal process
is depends on the pH value of the food.
Materials and Equipment :
Pineapples Refractometer
Syrup pH meter
Citric Acid Jacketed Steam Pot
CMC Sealing Machine
Method :
1) Weigh a pineapple.
2) Clean the pineapple and peel it.
3) Cut it into cubes. Wash and weigh.
4) Blanch the pineapple for about 1 minute at 90C 99C.
5) Prepare the syrup( 18 20 Brix). Take the Brix and pH value.
6) Fill the pineapple and syrup into cans which have been sterilized.
The syrup must be about 82C( hot filling ). Close the cans quickly.
7) Seal the cans by using sealing machine.
8) Sterile the cans in boiling water (100C) for about 30 minutes.
9) Cool the cans immediately to 38C and dry it.
10) Label the cans and evaluate it after 1 week.
Food Preservation ( MT 203)
Iman_Jan2011
Result :
Parameter Group
1 2 3 4 5
Initial syrup concentration
Final syrup concentration
Initial pH value
Final pH value
Cut out Brix
Initial weight
Net weight
Drained weight
% of yield
Discussion :
1) Specifically discuss and identify the importance of each methods in
the canning process.
2) Discuss the end product in chemical, physical and organoleptic
aspects.
3) Compare your end product (canned fruits) with the one in the
market.
Conclusion : References :
Food Preservation ( MT 203)
Iman_Jan2011
Lab : 3 Title : Examination of Can Double Seam Objectives : At the end of the lab, students must be able to:
1) inspect visually the external and internal of the can double seam
2) calculate the overlap percentage of the double seam
Introduction : Cans used in food processing should be properly constructed to
give the desired protection to food while being able to withstand the
severe treatment of heat and pressure. The double seam of a can should
be examined very carefully because the success of the canning depends
largely on the degree of perfection achieved in sealing the can
airtight.The external and internal conditions of the double seam should be
inspected visually and every measurements should be taken carefully to
judge the quality of the double seam.
Materials and Equipment : Screw gauge Seam Cutting Saw
Cutting Plier Magnifying Glass
Double Seam Can
Methods :
A. External Examination
1) Observe carefully all around the seam end, both on the body and lid.
2) Record the presence of defects if any such as V, droop, cut-over,
sharp seam etc.
3) Measure the seam length (L), seam thickness (T) and countersink
(CS) at 3-4 points by using screw gauge.
B. Internal Examination
1) Strip can end all around using plier and get a ring of the cover hook
portion.
2) Observe wave like wrinkle on inside surface of the cover hook and
record them.
Food Preservation ( MT 203)
Iman_Jan2011
3) Cut seam section at 3-4 points and observe for hooking, overlapping
and clearance using magnifying glass.
4) Separate body hook (BH) and cover hook (CH), without altering the
shape and measurement of double seam and record their lengths.
5) Find out average value of body hook (BH) and cover hook (CH).
6) Measure the end plate thickness (EPT) and body palte thickness
(BPT).
7) Calculate the overlap (OL) percentage by using following formula.
% OL = BH + CH + EPT L X 100
L ( 2 EPT + BPT )
Where :
BH : body hook length
CH : cover hook length
L : length / seam width
EPT : end plate thickness
BPT : body plate thickness
OL : overlap
Result :
Seam cutting point
External Examination Internal Examination
L
T
CS
BH
CH
EPT
BPT
%OL
1
2
3
Average
Discussion :
1) Discuss your observation for external examination ( defects).
2) Discuss your observation for internal examination ( wrinkles).
3) Discuss the percent of overlap from your result.
Conclusion : References :
Food Preservation ( MT 203)
Iman_Jan2011
Lab : 4 Title : Heat Penetration in Canned Food Objectives : At the end of the lab, students must be able to:
1) calculate the heat penetration value in selected canned food
Introduction : Heating times and temperature for canned food are based on the
destruction of the spores of Clostridium botulinum, as this organism has
been known to survive an inadequate process and thereafter grow up,
producing toxins that can cause sickness and in instances, death. The
temperature required to process food is based on their pH. Low acid food
required high temperature of processing. Meanwhile high acid foods,
required low temperature process. This is because acidic food produce
natural preservatives to microorganism (microorganism cannot stand in
acid condition).
Materials and Equipment : Food sample Retort
Thermometer Can
Thermocouple Table of Thermal Death Time
Methods :
1) Put the thermocouple into the can.
2) Fill the can with the sample and seal.
3) Connect the thermocouple with a thermometer and put into the retort.
4) Fill in the table below with the data from the thermometer.
5) Calculate the Fo value using formula and the Thermal Death Time.
6) Stop the stim when the Fo is 12.
7) Cool the cans immediately and dry.
Food Preservation ( MT 203)
Iman_Jan2011
Result : Fill in the data into the blank
Time of Processing (minute)
Temperature (C)
Thermal Death Time
Sum of Thermal Death Time
Calculate the Sterilizing Value (Fo) from the data
Sum of Thermal Death Time ( X ) = --------------------
Time Interval ( Y ) = --------------------
Sterilizing Value (Fo) = X x Y
= ----------------
Discussion :
1) Discuss the result of Sterilizing Value (Fo).
2) Discuss the effect of the Sterilizing Value (Fo) on food.
Conclusion : References :
Food Preservation ( MT 203)
Iman_Jan2011
Lab : 5 Title : Freezing Operation (Blast Freezer). Objectives : At the end of the lab, students must be able to :
1) describe the function of blast freezers compartments.
2) operate blast freezer.
Introduction : Air at -18 to - 40 C flows around packaged or unpackaged
product to freeze. The earliest freezing sharp freezing used still air
(no fans). This slow freezing process took 3 to more than 72 hours for
complete freezing - poor quality.
Now air blast freezing is used - rapid forced circulation of
air around product to get moderately fast freezing. Most common
arrangement is -29 C air moving at 2500 ft/min.
Materials and Equipment : Blast freezer
Sample
Methods :
1) Prepare the sample.
2) Determine each component of blast freezer and its functions.
3) Operate it and collect the frozen product.
Result :
Parametres Group
1 2 3 4 5
Initial Temperature
Final Temperature
Initial Time
Final Time
Time Differential
Food Preservation ( MT 203)
Iman_Jan2011
Discussion :
3) Specifically discuss the operation process of blast freezer and identify
the functions of each components.
4) Discuss the advantages and the disadvantages of blast freezer.
5) Discuss the suitable product that can be frozen using blast freezer.
Conclusion : References :
Food Preservation ( MT 203)
Iman_Jan2011
Lab : 6 Title : Oven Drying Objectives : At the end of the lab, students must be able to :
1) describe the function of oven and operate the oven.
2) determine a few factors affecting drying.
Introduction : Drying is one of the oldest methods of preserving food for later
use. It is simple, safe and easy. Drying removes the moisture from the
food so bacteria, yeast and mold can not grow and spoil the food. Drying
also slows down the action of enzymes (naturally occurring substances
which cause foods to ripen), but does not activate them. Because drying
removes moisture, the food becomes smaller and lighter in weight. When
the food is ready for use, the water is added back, and the food returns to
its original shape.
Materials andEquipment :
Oven
Potatoes
Methods :
1) Weight a few potatoes.
2) Peel the potatoes, cut into different size and shape.
3) Weight it again.
4) Blanch the potatoes for about 1 minute at 90C 99C.
5) Arrange the potatoes in a tray and dry it in an oven for about 4 - 5
hours at 60C.
6) After dried, weight the potatoes and get the moisture percent.
7) Evaluate the dried potatoes and determine the differences after dried.
Food Preservation ( MT 203)
Iman_Jan2011
Result :
Parameter Group
1 2 3 4 5
Initial weight
Weight of cutting
% of cutting
Dried weight
% of drying
% of moisture content
Discussion :
1) Compare the changes of weight and the differences of drying
percentage among samples.
2) Discuss the physical changes in colour, texture, shape and size.
3) Discuss factors affecting drying and the quality of the dried product.
Conclusion : References :
Food Preservation ( MT 203)
Iman_Jan2011
Lab : 7 Title : Drum Dryer Objectives : At the end of the lab, students must be able to :
1) describe the function of drum dryers compartments.
2) operate drum dryer.
Introduction : Drum driers are hollow drums of iron or stainless steel heated
internally usually by steam. Food to be dried must be in the form of liquid
or slurry and is applied to outer surface of drum by dipping, splashing,
spraying, spreading devices, or feed rollers. Transfers heat to food by
conduction is direct contact of food with heating surface.
Hollow drums, heated internally with steam have smooth surfaces
of machined steel. Food applied to the drum in a form of slurry. Food is
dried as it is carried by the rotating drum to a point where it is removed by
a fixed scraper. Foods that can be dried using drum dryer are potato
flakes, instant cereals (e.g. baby food), and fruit leather.
Materials and Equipment : Drum dryer
Sample
Methods : 1) Prepare the sample.
2) Determine each component of drum dryer and its functions.
3) Operate it and collect the dried product.
Result :
Parametres Group
1 2 3 4 5
Initial weight
Final weight
% of drying
Food Preservation ( MT 203)
Iman_Jan2011
Discussion :
1) Specifically discuss the operation process of drum dryer and identify
the functions of each components.
2) Discuss the physical changes in colour, texture, shape and size of
dried product.
3) Discuss the advantages and the disadvantages of drum dryer.
4) Discuss the suitable product that can be dried using drum dryer.
Conclusion : References :
Food Preservation ( MT 203)
Iman_Jan2011
Lab : 8 Title : Spray Dryer Objectives : At the end of the lab, students must be able to :
1) describe the function of spray dryers compartments.
2) operate spray dryer.
Introduction : Spray dryer is used for drying liquid products including milk,
coffee,and eggs.Initially developed for dairy products but has been used
for many food and pharmaceutical products.
Spray dryer using hot air for drying liquid food to become powder.
The liquid material is sprayed into the top of a chamber simultaneously
with hot air, which is also blown in at the top where it is in contact with a
stream of hot dry air. Dehydration is very rapid because of the large
surface area of droplets.
The cool, moist air exits near the bottom, and the dried particles
suspended in air flow move to separation equipment at the bottom and
are collected by gravity flow, or with the aid of scrapers that may also be
used to removed dried material from the walls or bottom. Cyclones
[conical-shaped collectors] may be used to collect particles escaping with
the exit air.
Materials and Equipment : Spray dryer
Milk
Methods : 1) Prepare the sample.
2) Determine each component of spray dryer and its functions.
3) Operate it and collect the dried product.
Ingredient Weight (gram)
Milk Powder 400
Water 3000
Dextrin 30
Food Preservation ( MT 203)
Iman_Jan2011
Result :
Parametres Group
1 2 3 4 5
Initial weight
Final weight
% of drying
Discussion :
1) Specifically discuss the operation process of spray dryer and identify
the functions of each components.
2) Discuss the physical changes in colour, texture, shape and size of
dried product.
3) Discuss the advantages and the disadvantages of spray dryer.
4) Discuss the suitable product that can be dried using spray dryer.
Conclusion : References :
Food Preservation ( MT 203)
Iman_Jan2011
Lab : 9 Title : The Effects of Food Additive On Food Objectives : At the end of the lab, students must be able to :
1) determine the suitable limit for food additive.
2) evaluate the effects of food additive on food.
Introduction : Food Additives , natural and synthetic compounds added to food
to supply nutrients, to enhance color, flavor, or texture, and to prevent or
delay spoilage. Some additives can inactivates or kill micro-organisms,
retard chemical spoilage. All food additives are carefully regulated by
federal authorities and various international organizations to ensure that
foods are safe to eat and are accurately labeled.It is important to note that
food additives are not all bad. There are often good and proper reasons
for using additives in the commercial preparation of foods. Unfortunately,
additives have received a bad press because they are used on occasions
to disguise inferior products.
Materials and Equipment: Dried Chilli - 1 kg
Water - 2.5 L
Natrium Benzoat
Methods :
1) Weigh the chilli.
2) Cut and wash the chilli.
3) Boil in boling water 10 minutes.
4) Blend the chilli with water.
5) Divide the mixture into 7 portion.
6) Put each portion with 0.2%, 0.15%, 0.125%, 0.1%, 0.075%, 0.05%
and 0% of Natrium Benzoate.
7) Check pH value for each portion.
8) Store each portion in a plastic container for 2 weeks.
9) Observe the containers and check the pH value every 2 days. Record
the observation and the pH value.
Food Preservation ( MT 203)
Iman_Jan2011
Result :
Day Observation
2
4
6
8
10
12
14
Discussion :
1) Discuss your observation for every 2 days.
2) Discuss your observation after 2 weeks.
3) Discuss the function of Natrium Benzoat.
Conclusion : References :
Food Preservation ( MT 203)
Iman_Jan2011
Lab : 10 Title : Food Fermentation ( Preparation of Tapai Pulut ) Objectives : At the end of the lab, students must be able to :
1) Describe the fermentation process of Tapai Pulut.
2) determine the organoleptic characteristics of Tapai Pulut.
Introduction : Fermentation is the use of biological processes to make products.
Its major uses are in the production or preservation of food. Fermentation
is not new. For many centuries fermentation has used micro-organisms to
make beer, yogurt and cheese.
The basis of the fermentation process is the conversion of sugar
(glucose) to alcohol or to lactic acid by enzymes. Fermentation acts as a
preservation method by producing an acid which lowers the pH of the
product, converting a perishable food into one that has a longer shelf-life.
Materials and Equipment: Beras pulut - 500g
Ragi - 1g
Water - 450ml
Plastic container
Methods :
1) Clean the beras pulut. Wash and soak it for about 15 minutes.
2) Pour the water and wash again.
3) Cook the rice with 450ml water for about 5-10 minutes.
4) Cooled the rice to 400C on a clean plastic after cooked.
5) Spread the ragi on the rice.
6) Mix the ragi and the rice carefully.
7) Put the rice into the plastic containers.
8) Close it and ferment for about 45 hours.
Food Preservation ( MT 203)
Iman_Jan2011
Result : Sensory evaluation of final product for the organolleptic characteristics ( scoring test).
Discussion :
1) Specifically discuss each step in preparing tapai pulut and identify the
importance of each step.
2) Discuss the end product in chemical, physical and organoleptic
aspects.
3) Compare your end product with the other group.
Conclusion : References :
Food Preservation ( MT 203)
Iman_Jan2011