EFFECT OF DIFFERENT POSTHARVEST TREATMENTS ON
KEEPING QUALITY OF APRICOT (Prunus armeniaca L.) PRODUCED
IN NORTHERN AREAS OF PAKISTAN
SARTAJ ALI 07-arid-09
Department of Food Technology
Faculty of Crop and Food Sciences Pir Mehr Ali Shah
Arid Agriculture University, Rawalpindi Pakistan
2013
ii
EFFECT OF DIFFERENT POSTHARVEST TREATMENTS ON KEEPING QUALITY OF APRICOT (Prunus armeniaca L.) PRODUCED
IN NORTHERN AREAS OF PAKISTAN
by
SARTAJ ALI (07-arid-09)
A thesis submitted in partial fulfillment of the requirements for the degree of
Doctor of Philosophy
in
Food Technology
Department of Food Technology Faculty of Crop and Food Sciences
Pir Mehr Ali Shah Arid Agriculture University, Rawalpindi
Pakistan
2013
iii
CERTIFICATION
I hereby undertake that this research is an original one and no part of this thesis falls
under plagiarism. If found otherwise at any stage, I will be responsible for the consequences.
Student’s Name: Sartaj Ali Signature: ____________
Registration No: 07-arid-09 Date:
Certified that the contents and form of the thesis entitled “Effect of different
postharvest treatments on keeping quality of apricot (Prunus armeniaca L.) produced in Northern Areas of Pakistan” submitted by Sartaj Ali have been found satisfactory for the requirement of the degree.
Supervisor: __________________________ (Prof. Dr. Tariq Masud)
Member: ___________________________
(Dr. Anwaar Ahmed)
Member: ___________________________ (Prof. Dr. Irfan Ul-Haque) Chairman: _____________________ Dean: ______________________ Director Advanced Studies: ___________________________
iv
IN THE NAME OF ALLAH THE MOST MERCIFUL THE MOST BENEFICIANT
v
I Dedicate
This Humble Effort
To My Parents
vi
CONTENTS
Page Certification iii
Dedication v
List of Tables xii
List of Figures xiii
List of Abbreviations xvi
Acknowledgement xvii
ABSTRACT 01 1. INTRODUCTION 02 2. REVIEW OF LITERATURE 05 2.1 POSTHARVEST PHYSIOLOGY 05
2.2 LOSS REDUCTION TECHNOLOGY 08
2.3 CALCIUM CHLORIDE 09
2.4 SALICYLIC ACID 10
2.5 MODIFIED ATMOSPHERE PACKAGING 11
3. MATERIALS AND METHODS 13 3.1 PHYSICO-CHEMICAL CHARACTERIZAYION OF APRICOT GENOTYPES 13
3.2 EFFECT OF POSTHARVEST TREATMENTS ON KEEPING QUALITY OF
APRICOT 14
3.2.1 Effect of Calcium chloride on the Keeping Quality of Apricot 14 3.2.2 Effect of Salicylic acid on the Keeping Quality of Apricot 14
3.2.3 Effect of Packaging Material on Keeping Quality of Apricot 15 3.3 EFFECT OF COMBINE TREATMENT ON KEEPING QUALITY OF
APRICOT 15 3.4 PHYSICO-CHEMICAL PROPERTIES OF APRICOT 16
3.4.1 Proximate Composition 16
3.4.1.1 Moisture content 16
3.4.1.2 Dry matter 16
3.4.1.3 Ash 16
vii
3.4.1.4 Crude fiber 17
3.4.1.5 Crude fat 17
3.4.1.6 Crude protein 17
3.4.1.7 Sugars estimation 18
3.4.2 Mineral Contents 18
3.4.3 Technological Properties 18
3.4.3.1 Fruit weight 19
3.4.3.2 Fruit size and shape 19
3.4.4 Post harvest Quality Attributes 19
3.4.4.1 Firmness 19
3.4.4.2 Weight loss 19
3.4.4.3 Total soluble solids 20
3.4.4.4 pH 20
3.4.4.5 Titratable acidity 20
3.4.4.6 Ascorbic acid 20
3.4.4.7 Total phenolic contents 21
3.4.4.8 Total carotenoids 21
3.4.4.9 Antioxidant activity 22
3.4.4.10 Extraction of enzymes 22
3.4.4.11 Total soluble protein 22
3.4.4.12 Polyphenol oxidase assay 23
3.4.4.13 Peroxidase assay 23
3.4.4.14 Catalase assay 24
3.4.4.15 Total viable count 24 3.4.4.16 Total Fungal Count 25
3.4.5 Sensory Attributes 25
3.4.6 Statistical Analysis 25
4. RESULTS AND DISCUSSION 26 4.1 PHYSICO-CHEMICAL CHARACTERISTICS OF APRICOT GROWN
IN NORTHERN AREAS OF PAKISTAN 26
4.1.1 Proximate Composition of Apricot 26
viii
4.1.2 Chemical and Functional Properties of Apricot 30
4.1.3 Mineral Contents 36
4.1.4 Technological Properties of Apricot 37
4.1.5 Sensory Attributes of Apricot 40
4.2 EFFECT OF POST HARVEST TREATMENTS ON QUALITY
ATTRIBUTES OF APRICOT DURING AMBIENT STORAGE 44
4.2.1 Effect of Different Concentrations of Calcium Chloride on Keeping
Quality of Apricot at Ambient Conditions 44
4.2.1.1 Fruit firmness as affected by different CaCl2 concentrations 44
4.2.1.2 Fruit weight loss as affected by different CaCl2 concentrations 46
4.2.1.3 Total soluble solids as affected by different CaCl2 concentrations 49
4.2.1.4 Reducing sugars as affected by different CaCl2 concentrations 51
4.2.1.5 Total sugars as affected by different CaCl2 concentrations 51
4.2.1.6 Non- reducing sugars as affected by different CaCl2 concentrations 53
4.2.1.7 Fruit pH as affected by CaCl2 concentration 57
4.2.1.8 Titratable acidity as affected by different CaCl2 concentrations 57
4.2.1.9 Ascorbic acid as affected by different CaCl2 concentrations 61
4.2.1.10 Total phenolic contents as affected by different CaCl2 concentrations 62
4.2.1.11 Total carotenoids as affected by different CaCl2 concentrations 65
4.2.1.12 Antioxidant activity as affected by different CaCl2 concentrations 66
4.2.1.13 Polyphenol oxidase activity as affected by different CaCl2 concentrations 68
4.2.1.14 Peroxidase activity as affected by different CaCl2 concentrations 72
4.2.1.15 Catalase activity as affected by different CaCl2 concentrations 73 4.2.1.16 Fruit color as affected by different CaCl2 concentrations 77
4.2.1.17 Fruit flavor as affected by different CaCl2 concentrations 78
4.2.1.18 Fruit taste as affected by different CaCl2 concentrations 81
4.2.1.19 Fruit texture as affected by different CaCl2 concentrations 81
4.2.1.20 Overall acceptability as affected by different CaCl2 concentrations 83
4.2.1.21 Microbial load as affected by different CaCl2 concentrations 85
4.2.2 Effect of Salicylic acid on Keeping Quality of Apricot 87
4.2.2.1 Fruit firmness as affected by salicylic acid concentrations 90
ix
4.2.2.2 Fruit weight loss as affected by salicylic acid concentrations 92
4.2.2.3 Total soluble solids as affected by salicylic acid concentrations 94
4.2.2.4 Reducing sugars as affected by salicylic acid concentrations 96
4.2.2.5 Total sugars as affected by salicylic acid concentrations 98
4.2.2.6 Non-reducing sugars as affected by salicylic acid concentrations 100
4.2.2.7 Fruit pH as affected by salicylic acid concentrations 101
4.2.2.8 Titratable acidity as affected by salicylic acid concentrations 103
4.2.2.9 Ascorbic acid as affected by salicylic acid concentrations 106
4.2.2.10 Total phenolic content as affected by salicylic acid concentrations 107
4.2.2.11 Total carotenoids as affected by salicylic acid concentrations 110
4.2.2.12 Antioxidant activity as affected by salicylic acid concentrations 111
4.2.2.13 Polyphenol oxidase activity as affected by salicylic acid concentrations 113
4.2.2.14 Peroxidase activity as affected by salicylic acid concentrations 115
4.2.2.15 Catalase activity as affected by salicylic acid concentrations 119
4.2.2.16 Fruit color as affected by salicylic acid concentrations 119
4.2.2.17 Fruit flavor as affected by salicylic acid concentrations 122
4.2.2.18 Fruit taste as affected by salicylic acid concentrations 123
4.2.2.19 Fruit texture as affected by salicylic acid concentrations 125
4.2.2.20 Overall acceptability as affected by salicylic acid concentrations 127
4.2.2.21 Microbial load as affected by salicylic acid concentrations 130
4.2.3 Effect of Packaging Material on Quality Attributes of Apricot
during Ambient Storage 133
4.2.3.1 Fruit firmness as affected by packaging materials 133
4.2.3.2 Fruit weight loss as affected by packaging materials 134
4.2.3.3 Total soluble solids as affected by packaging materials 136
4.2.3.4 Reducing sugars as affected by packaging materials 139
4.2.3.5 Total sugars as affected by packaging materials 142
4.2.3.6 Non-reducing sugars as affected by packaging materials 144
4.2.3.7 Fruit pH as affected by packaging materials 146
4.2.3.8 Titratable acidity as affected by packaging materials 146
4.2.3.9 Ascorbic acid as affected by packaging materials 149
x
4.2.3.10 Total phenolic contents as affected by packaging materials 151
4.2.3.11 Total carotenoids as affected by packaging materials 153
4.2.3.12 Antioxidant activity as affected by packaging materials 156
4.2.3.13 Polyphenol oxidase as affected by packaging materials 158
4.2.3.14 Peroxidase activity as affected by packaging materials 160
4.2.3.15 Catalase activity as affected by packaging materials 162
4.2.3 .16 Fruit color as affected by packaging materials 164
4.2.3.17 Fruit flavor as affected by packaging materials 166
4.2.3.18 Fruit taste as affected by packaging materials 169
4.2.3.19 Fruit texture as affected by packaging materials 171
4.2.3.20 Overall acceptability as affected by packaging materials 171
4.2.3.21 Microbial load as affected by packaging materials 173
4.3 Combine Effect of Chemical Treatments and Packaging Films on
Postharvest Quality of Apricot during Storage 177
4.3.1 Fruit firmness as affected by combine treatment 177
4.3.2 Fruit weight loss as affected by combine treatment 179
4.3.3 Total soluble solids as affected by combine treatment 181
4.3.4 Reducing sugars as affected by combine treatment 183
4.3.5 Total sugars as affected by combine treatment 185
4.3.6 Non-reducing sugars as affected by combine treatment 186
4.3.7 Fruit pH as affected by combine treatment 189
4.3.8 Titratable acidity as affected by combine treatment 189 4.3.9 Ascorbic acid as affected by combine treatment 192
4.3.10 Total phenolic contents as affected by combine treatment 194
4.3.11 Total carotenoids as affected by combine treatment 195
4.3.12 Antioxidant activity as affected by combine treatment 198
4.3.13 Polyphenol oxidase activity as affected by combine treatment 198
4.3.14 Peroxidase activity as affected by combine treatment 200
4.3.15 Catalase activity as affected by combine treatment 202
4.3.16 Fruit color as affected by combine treatment 204
4.3.17 Fruit flavor as affected by combine treatment 206
xi
4.3.18 Fruit taste as affected by combine treatment 208
4.3.19 Fruit texture as affected by combine treatment 211 4.3.20 Overall acceptability as affected by combine treatment 213
4.3.21 Microbial load as affected by combine treatment 213
SUMMARY 217 CONCLUSIONS AND FUTURE DIRECTIONS 221 LITERATURE CITED 222
xii
List of Tables
Table No. Page
1. Proximate composition of the apricot varieties 27
2. Chemical and functional composition of apricot varieties 32
3. Mineral contents in apricot varieties 38
4. Weight dimensions of apricot 41
4. Geometrical properties of apricot 42
5. Sensory attributes of apricot varieities 43
xiii
List of Figures
Figure No. Page
1. Fruit firmness of apricot under different CaCl2 concentrations 45
2. Weight loss in apricot under different CaCl2 concentrations 48
3. Total soluble solids in apricot under different CaCl2 concentrations 50
4. Reducing sugars in apricot under different CaCl2 concentrations 52 5. Total sugars in apricot under different CaCl2 concentrations 54
6. Non-reducing sugars in apricot under different CaCl2 concentrations 56
7. pH in apricot under different CaCl2 concentrations 58
8. Titratable acidity in apricot under different CaCl2 concentrations 60
9. Ascorbic acid in apricot under different CaCl2 concentrations 63
10. Total phenolics in apricot under different CaCl2 concentrations 64
11. Total carotenoids in apricot under different CaCl2 concentrations 67
12. Antioxidant activity in apricot under different CaCl2 concentrations 69
13. Polyphenol oxidase activity in apricot under different CaCl2 concentrations 71
14. Peroxidase activity in apricot under different CaCl2 concentrations 74
15. Catalase activity in apricot under different CaCl2 concentrations 76
16. Color in apricot under different CaCl2 concentrations 79
17. Flavor in apricot under different CaCl2 concentrations 80
18. Taste in apricot under different CaCl2 concentrations 82
19. Texture in apricot under different CaCl2 concentrations 84
20. Overall acceptability in apricot under different CaCl2 concentrations 86
21. Total bacterial count in apricot under different CaCl2 concentrations 88
22. Total fungal count in apricot under different CaCl2 concentrations 89
23. Fruit firmness of apricot under different concentrations of salicylic acid 91
24. Weight loss in apricot under different concentrations of salicylic acid 93
25. Total soluble solids in apricot under different concentrations of salicylic acid 95
26. Non-reducing sugars in apricot under different concentrations of salicylic acid 96
27. Total sugars in apricot under different concentrations of salicylic acid 97
28. Non-reducing sugars in apricot under different concentrations of salicylic acid 99
xiv
29. pH of apricot under different concentrations of salicylic acid 102
30. Titratable acidity of apricot under different concentrations of salicylic acid 104
31. Ascorbic acid in apricot under different concentrations of salicylic acid 105
32. Total phenolics in apricot under different concentrations of salicylic acid 108
33. Total carotenoids in apricot under different concentrations of salicylic acid 109
34. Antioxidant activity in apricot under different concentrations of salicylic acid 112
35. Polyphenol oxidase activity in apricot under different concentrations of salicylic
acid 114
36. Peroxidase activity in apricot under different concentrations of salicylic acid 116
37. Catalase activity in apricot under different concentrations of salicylic acid 118
38. Color of apricot under different concentrations of salicylic acid 120
39. Flavor of apricot under different concentrations of salicylic acid 122
40. Taste of apricot under different concentrations of salicylic acid 124
41. Texture of apricot under different concentrations of salicylic acid 126
42. Overall acceptability of apricot under different concentrations of salicylic acid 128
43. Total bacterial count in apricot under different concentrations of salicylic acid 129
44. Total bacterial count in apricot under different concentrations of salicylic acid 131
45. Fruit firmness of apricot under different packaging systems 132
46. Weight loss in apricot under different packaging systems 137
47. Total soluble solids in apricot under different packaging systems 140
48. Reducing sugars in apricot under different packaging systems 141
49. Total sugars in apricot under different packaging systems 143
50. Non-reducing sugars in apricot under different packaging systems 145
51. pH of apricot under different packaging systems 147
52. Titratable acidity in apricot under different systems 148
53. Ascorbic acid in apricot under different packaging systems 150
54. Total phenolic compounds in apricot under different packaging systems 152
55. Total carotenoids in apricot under different packaging systems 154
56. Antioxidant activity in apricot under different packaging systems 157
57. Polyphenol oxidase activity in apricot under different packaging systems 159
58. Peroxidase activity in apricot under different packaging systems 161
xv
59. Catalase activity in apricot under different packaging systems 163
60. Color of apricot under different packaging systems 165
61. Flavor of apricot under different packaging systems 167
62. Taste of apricot under different packaging systems 170
63. Texture of apricot under different packaging systems 172
64. Overall acceptability of apricot under different packaging systems 174
65. Total bacterial count in apricot under different packaging systems 175
66. Total fungal count in apricot under different packaging systems 176
67. Fruit firmness in apricot under combine treatment 178
68. Weight loss in apricot under combine treatment 180
69. Total soluble solids in apricot under combine treatment 182
70. Reducing sugars in apricot under combine treatment 184
71. Total sugars in apricot under combine treatment 187
72. Non-reducing sugars in apricot under combine treatment 188
73. pH in apricot under combine treatment 190
74. Titratable acidity in apricot under combine treatment 191
75. Ascorbic acid in apricot under combine treatment 193
76. Total phenoilcs in apricot under combine treatment 196
77. Total carotenoids in apricot under combine treatment 197
78. Antioxidant activity in apricot under combine treatment 199
79. Polyphenol oxidase activity in apricot under combine treatment 201
80. Peroxidase activity in apricot under combine treatment 203
81. Catalase activity in apricot under combine treatment 205
82. Color in apricot under combine treatment 207
83. Flavor in apricot under combine treatment 209
84. Taste in apricot under combine treatment, 210
85. Texture in apricot under combine treatment 212
86. Overall acceptability of apricot under combine treatment 214
87. Total bacterial count in apricot under combine treatment 215
88. Total fungal count in apricot under combine treatment 216
xvi
LIST OF ABBREVIATIONS
Cfu Colony forming units
CAT Catalase
DPPH 2, 2-diphenyl-l-picrylhydrazyl
GAE Gallic acid equivalent
kgf Kilogram force
PGA Polygalacturonase
POD peroxidase
PPO polyphenoloxidase
PVC Polyvinyl chloride
xvii
ACKNOWLEDGMENTS
All praises to Almighty Allah, the compassionate and merciful, whose bounteous
blessing gave me the potential and opportunity to make this humble contribution. Blessing of
Allah on Holy Prophet, Muhammad (PBUH) the city of knowledge and his Ahlulbait (AS),
who made us aware about our Creator and guided us to the track which leads us to the
success.
I feel privileged to express my profound gratitude to my supervisor, Prof. Dr. Tariq
Masud, Chairman Department of Food Technology, whose motivation and guidance at every
step towards educational excellence made me a student of the scientific world. I also extend
my feelings of gratitude to the members of my supervisory committee Dr. Anwaar Ahmed
and Prof. Dr. Irfan-Ul-Haque for their indispensible guidance and help while completing this
work. I am thankful to all faculty members of Food Technology Department especially to
Dr. Asif Ahmad, Mrs. Asia Latif and Dr. Farzana Siddique for their cooperation. I am too
much grateful to Sana-ul-Allaha and M. Rashid of Central Lab, Syed Yasin of Deptt. of
Biochemistry and Syed Khalid Sherazi (Shah Photostat) for their sincere support during my
research.
Very special thanks to my PhD fellows Mr. Talat Mahmood and Mr. Kashif Sarfarz
Abbasi for their treatment as a family member and all out help through thick and thin during
this period. Thanks are also due to Muhammad Zafar Iqbal Lab. Technician for his
cooperation. I am extending my thanks to my students Mr. Amjad Ali and Shehzad Hussain
for their time whenever I needed. I also avail this opportunity to thank Haji Kamal Shah
(Malook General Store) for his extended helping hand throughout my educational career. I am
xviii
also obliged to my nephew Fakhar Haider who proved to be a blessing at certain critical
stages.
I am extending my heartiest admirations to the sacrifices of my Loving Parents and
my wife who actually made it possible for me to continue my education and also my children
who missed me in their early development ages when they deserve to be cared. Their hands
were raised for prayers before Almighty Allah for my success. I bow my head and thank to
all. I pray to Allah Almighty to extend me His blessings so that I could serve them in the rest
of my life.
(Sartaj Ali)
1
ABSTRACT
Apricot is a highly nutritious fruit with a rich composition of health promoting components
with a unique taste. Due to its perishable nature, enormous amounts of fresh produce goes to
waste during peak season. In order to reduce the postharvest losses, the present study was
designed in three phases. Initially, twelve commonly grown cultivars were characterized for
their proximate composition, biochemical attributes, mineral contents and some technological
traits. Among the tested cultivars, Habi variety had best physico-chemical and sensory
attributes, Jahangir was rich in mineral contents, while Mirmalik had better technological
traits. On the basis of overall quality characteristics, Habi variety was selected for the
postharvest studies. The second phase was comprised of three experiments. Different
concentrations of CaCl2 (1, 2, 3 and 4% w/v), salicylic acid (0.5, 1, 1.5 and 2 mM w/v),
polyethylene films of varying densities and wrapping paper as packaging material were
applied to determine suitable treatment. Physiological, biochemical and microbial attributes
were analyzed at two day interval. Three percent CaCl2 maintained quality attributes with
lower microbial load and higher sensory acceptance up to 12 days followed by 2, 4% CaCl2
respectively during ambient storage. Similarly, 2 mM salicylic acid and low density
polyethylene film significantly retained all the tested nutritional and biochemical traits. The
combined effect of the best selected treatments (3% CaCl2, 2 mM salicylic acid and LDPE
packaging with KMnO4) maintained acceptable quality of the fruit up to 18 days at ambient
temperature. The present study provides a baseline for the effective postharvest application of
calcium chloride and salicylic acid along with polyethylene packaging on apricot in order to
reduce losses and increase its availability in the distant markets.
2
Chapter 1
INTRODUCTION
Apricot is an important source of livelihood for the peoples of Gilgit-Baltistan. It is the
abundant and most preferred fruit among horticultural crops and accounts for 62 percent of
total fresh fruit production (DOA, 2009). The major income from horticultural crops comes
from apricot after the potato. An average farming family earns 20 percent of their agricultural
income from apricot only (Jasra and Rafi, 2002). Sulfur dried and organic apricots are
marketed in the local and national market and now some sizable portion is also exported to
the international market.
Postharvest shelf life is affected by a number of factors, i.e. agronomic practices,
harvesting, handling, climatic and storage conditions as well as spoilage microorganisms. The
climacteric nature of apricot makes it susceptible to postharvest decay and spoilage as a result
of rapid ripening, accompanied by flesh softening, tissue browning and complete senescence
(Egea et al., 2007). Apricots are considered vulnerable to dehydration and shrinkage, owing to
their non waxy skin. Two main physiological disorders appear in apricot that are internal
browning and breakdown of tissues which reduce their storage life (Manolopoulou and
Mallidis, 1999). Tissues breakdown results in the liberation of phenolic compounds,
carotenoids and enzymes that are compartmentalized within the cellular structure of fruits.
These contents further degrade with increased metabolic activities, resulting in quantity and
quality loss. The levels of phenolic compounds reduce with the increased enzyme activity
2
3
because they are utilized as substrates by respiration process and many enzyme systems (De
Regal et al., 2000). Therefore cellular integrity of the commodity is important towards the
conservation of nutritional contents.
Postharvest shelf life determines the suitability of any fruit for its distant marketing.
The core purpose of postharvest treatment of fruits is to present good quality fruit to the end
user in markets for away from the production regions (Fuchs and Zauberman, 1987).
Researchers and scientists are interested in extending shelf life of economically important
fruits so as to increase their useful life. Apricots have limited storage life and can only stay
fresh for 3-5 days at ambient temperatures and 1-4 weeks when stored at -0.5 to 0 oC and
90±5% relative humidity, depending on cultivar (Fan et al., 2000). Being climacteric in
nature, apricots undergo rapid ripening, resulting into flesh softening and complete
senescence (Egea et al., 2007; Agar and Polate, 1995). Owing to their non waxy skin, apricots
are considered susceptible to desiccation and shriveling. During storage, two main
physiological disorders appear in apricots that are internal browning and breakdown of tissues
which reduce their storage life (Manolopoulou and Mallidis, 1999).
Fresh fruit wastage in case of apricot in Gilgit-Baltistan is up to 44 percent annually
(DOA, 2009) due to inappropriate postharvest management. Being an important economic
crop of that area, no serious attention has been paid so far to avoid the huge postharvest
losses. The area is very rich in terms of a wide array of indigenous apricot genotypes with
more than 60 different varieties (DAO, 2009), which were needed to be explored for their
nutritional and health potentials. In addition, no systematic study has been reported on the
effect of different chemical treatments and packaging application during the post harvest
4
storage. It is therefore hypothesized that the application of generally accepted as safe (GRAS)
chemicals and cheap indigenous packaging material will improve the storage life of this
perishable commodity at ambient conditions. The study of storage associated changes in
different quality attributes of apricot would also be helpful to sketch the physiological and
biochemical modifications during the prolonged storage. A comprehensive study was
therefore planned to achieve the following objectives:
1. To determine the nutritional and technological properties of locally grown varieties of apricot
to furnish a ready reference data.
2. To evaluate the effect of chemical treatments (CaCl2 and Salicylic acid) on storage life of
apricots.
3. To select the appropriate packaging material for maintaining quality during storage.
4. To assess the combined effect of chemical treatments and packaging material on postharvest
quality attributes of apricots during ambient storage.
5
Chapter 2
REVIEW OF LITERATURE
Fruits are living commodities and the ripening and aging continues even after harvest
resultingintoo tissue breakdown (Chaudhury, 2008). The most important mechanisms are
respiration, ethylene production, enzymatic activities and gaseous concentration of the storage
environment responsible for quality loss. Many physiological processes taking place within
the cellular structure and cause gradual changes in the quality of the produce. During the
course, respiration continues, exchange of gases takes place and ethylene is produced that
accelerates the ripening process (Anon, 2008).
2.1 POSTHARVEST PHYSIOLOGY
Fruits are classified into climacteric and non-climacteric based on their ripening
behavior. Climacteric fruits ripen even after harvest, while non-climacteric fruits do not ripen
when detached from the plant. The most important biological process is respiration
accompanied by release of ethylene in climacteric fruits. As a growth regulating hormone,
ethylene plays significant role in shelf life of fruits by affecting the ripening rate (Pech et al.,
2008). The concomitant changes result into flesh softening, the development of color and
production of aroma compounds are attributed to the evolution of ethylene. Ethylene
biosynthesis takes place through enzyme mediated metabolic pathway by using sulfur
containing amino acid methionine as the biological precursor (Argueso et al., 2007).
5
6
Methionine (Met) is converted to S-adinosyl-L-methionine (SAM) by S-adinosylmethionine
synthetase and then SAM is converted to 1-amino-cyclopropane 1-carboxylic acid (ACC) and
5´-deoxy-5´ methylthioadnosine (MTA) by 1-aminocyclopropane-1-carboxylase synthase
(ACS). The enzyme ACC oxidase then converts ACC into ethylene (C2H4), while the MTA is
recycled into methionine via Yang cycle, which allows ethylene production without using the
endogenous reserves of methionine (Miyazaki and Yang, 1987). The ethylene evolution
pathway can be simply illustrated as under:
Figure: Ethylene biosynthesis pathway (Arteca and Arteca, 1999)
Ethylene accumulation in the tissues accelerates the rate of respiration which results in to
degradation of structural carbohydrates. Respiration is the major factor contributing to
postharvest losses. It enhances senescence through converting sugars into energy (Nourian et
al., 2003).
Ethylene emission in apricot fruit is correlated to excessive softening and firmness
loss (Botondi et al., 2003). The underlying mechanism is conversion of structural
carbohydrates into simple sugars which function as an energy source for continued
7
respiration. Respiration and evolution of ethylene speed up the ripening process, leading to
accelerated membrane deterioration, nutrient depletion and excessive water losses. During
ripening, respiration considerably increases over a short period of time (Eskin, 1990). If the
storage atmosphere (temperature, O2 and CO2) is not properly managed, rapid ripening leads
to internal tissue breakdown with the production of volatile characteristics of over ripe fruit
(Mathooko, 1995).
The maturity stage at harvest strongly influences the ripening process during storage;
since harvest at early or late maturity both affects the apricot fruit quality (Manolopoulou and
Mallidis, 1999). Post harvest handling, physical damage and wounding of tissues induce
deleterious physico-chemical changes within the product (Saltviet, 1997). These symptoms
might be visual as loss of color, shrinkage due to water removal, browning, or flavor changes,
microbial contamination and internal quality deterioration.
The respiration process involves oxygen and carbohydrates to make intermediate
products and eventually CO2 and water. This mechanism accompanied by enzymatic activities
cause excessive textural softening leading to adverse effects on the nutritional and sensory
quality of produce (Prasanna et al., 2007). Similarly, PPO and POD assist in browning
reactions and thus deteriorate fruit color. In contrast to this, certain enzymes play a protective
role against the destructive mechanism evolved during ripening. These are catalase and
superoxide dismutase along many others which scavenging free radicals harmful to the
tissues. Reactive oxygen species involve in senescence and aging of fresh commodities (Yang
et al., 2008). These enzymes avert the harmful effect of active oxygen species (O2-) and
hydroxyl groups i.e. HO- and H2O2 by converting them into the water. Lower activities of
CAT and SOD may result into tissue browning in may fruits, however the pace of action of
different enzymes vary with the species and variety of fruits (Vicente et al., 2007).
8
2.2 LOSS REDUCTION TECHNOLOGY
In spite of significant progress made in increased production of food commodities
around the globe, nearly half of the population from third world has no access to adequate
food. Quantitative and qualitative losses of food are tremendous in developing world where
food shortage already exists due to poor management techniques and lack of skill. Among the
realm of factors, postharvest food losses occurring during harvest and in the marketing chain
are the most common (FAO, 2008).
Consumer quality is defined in terms of color, flavor and physical integrity of the fruit.
The visible quality is affected by respiration and metabolic activities which deteriorate
nutritional contents and sensory attributes. Postharvest handling and storage conditions
strongly influence ripening and subsequent decay of fresh commodities. Among different loss
reduction technologies, chemical elicitors, packaging, controlled atmospheric storage,
modified atmospheric storage, sub-atmospheric, hypobaric, low temperature storage as well as
drying, dehydration and irradiation are being applied to reduce postharvest losses of
horticultural commodities (Kader, 1997; Soliva and Martin, 2006). While selecting an
appropriate loss reduction technology, a number of factors are required to be considered i.e.
cost effectiveness, simple and easy to handle, energy efficient and maintenance of maximum
quality attributes of the produce. Based on the physiological responses during storage, a
variety of synthetic or plant based chemical compounds as surface coatings, anti-aging, anti
antioxidants, anti-ripening, ethylene scavengers, firming and antimicrobial agents generally
recommended as safe (GRAS) are widely used to delay ripening and retard decay.Besides
this, packaging is also crucial to maintain freshness and nutritional content of fresh
commodities during storage and marketing. Today’s consumer is health conscious and
9
demands food of natural origin and devoid of chemical and pesticide residue (Valero et al.,
2011). The focus of most of the researchers is the preservation technologies utilizing plant
based compounds for postharvest quality retention of perishable commodities. Among a wide
range of natural agents; calcium based compounds and salicylic acid are now increasingly
investigated for their roles in the shelf life extension and eliminating postharvest decay of
fruits. Previous studies on different fruits regarding the effect of chemical treatments in
combination with packaging are reviewed here below:
2.3 CALCIUM CHLORIDE
In post harvest management chemical preservatives are widely used to maintain the
final quality of the fruits. Calcium chloride is an example of such chemicals that have
considerable impact on the shelf life of different fruits and vegetables. It delays aging or
ripening, reduce post harvest decay, control development of many physiological disorders and
increase the calcium content in the fruit and thus improve the nutritional value. Roy et al.
(1996) states that calcium infiltration in to fruit tissues delays softening and ripening rate by
retarding disintegration of cell walls. The role of calcium in maintenance and regulation of
cell function is evident from the fact that it is essential to have Ca2+ in the extra-cellular
solutions to ensure the selective permeability or membrane integrity. Calcium is also an
integral part of cell wall and provides stability and rigidity to it (El-Shemy, 1998). Previous
studies have reported that calcium sprays increased calcium concentration in apricot fruit and
improved shelf life by increasing fruit firmness (Rease et al., 1999). It has further been
suggested that pre and postharvest application of calcium salts maintain firmness and slow
down the ripening process of apricot fruits (Souty et al., 1995). It modifies intra-cellular and
extra-cellular processes, which delay ripening and softening, lowers the rates of color change,
10
CO2 and ethylene production, increase in sugar and reduction in total acid content (Conway,
1987). Antunes, et al. (2006) investigated the effect of post harvest calcium chloride
application on fruit storage ability and quality of Beliana and Lindo apricot (prunus
armeniaca L.) cultivars. They concluded that dipping apricot fruits in concentrations up to 1%
CaCl2 could improve storage ability. It has been established that calcium ions link up peptic
molecules in the middle lamella that are responsible for cell organization (Knee and Bartley,
1981). Therefore, softening may be due to the result of calcium loss from the middle lamella
or loss of its place in the linkage between the peptic molecules (Knee, 1982).
2.4 SALICYLIC ACID
Salicylic acid (SA) belongs to a group of phenolic compounds widely distributed in
plants and it is now considered as a hormonal substance playing an important role in
regulating plant growth and development (Wang et al., 2006). This is somewhat recently
known plant hormone with multiple modes of stress resistance in plants and has some
similarities in functions with ethylene (Asghari and Aghdam, 2010). As endogenous signal
molecules salicylic acid and methyl salicylate (MeS) play crucial roles to regulate numerous
growth and stress responses, including heat production, photosynthesis, transpiration, stomatal
conductance, ion uptake and transport, seed germination, crop yield, glycolysis and diseases
resistance (Klessing and Malamy, 1994). Salicylic acid has been reported to delay ripening of
fruits by inhibiting ethylene biosynthesis and maintain postharvest quality (Srivastava and
Dwivedi, 2000). External applications of salicylic acid affect many physiological mechanisms
(Zavala et al., 2004) and being a natural and safe phenolic source can effectively control
postharvest losses of horticultural crops (Asghari and Agdham, 2010). It is associated with a
number of mechanisms which strengthen the cellular structure and retard senescent events
11
that ultimately cause depletion of nutritional components. Wang et al. (2006) concluded that
salicylic acid maintained fruit firmness, reduced chilling injury and membrane lipid
peroxidation during cold storage in peach. It was further concluded that pre-storage SA
application provides useful ways for shelf life extension of peach fruit during storage.
Similarly, Shafiee et al. (2010) also observed that the SA application significantly reduced
weight loss, maintained fruit firmness and hue angle in strawberry fruit. Previous studies
suggesting that SA may be related to oxidative stress response during ripening of banana and
kiwi fruit as well as in postharvest diseases (Srivastava and Dwiyedi, 2000; Qin et al., 2003;
Zhang et al., 2003). Salicylic acid treatments have shown good results in controlling fungal
disease and delayed ripening in tomato, sweet cherry, strawberry, asparagus and Haward Kiwi
fruits (Pila et al., 2010; Yao and Tian, 2005; Wei et al., 2010; Aghdam et al., 2011). It has
been established that SA prolongs storage life by maintaining nutritional attributes and
controls the decay incidence during postharvest through inhibiting ripening and senescence
mechanisms (Pila et al., 2010).
2.5 MODIFIED ATMOSPHERE PACKAGING
To sustain the freshness of the produce, it is necessary to maintain the temperature,
gas concentrations and moisture in the packaging. The rate of respiration depends on the
concentration of oxygen. Slower respiration is achieved at lower concentrations of O2 and
vice versa. Best packaging modifies the atmosphere and the gaseous accumulation (O2, CO2
and C2H4) exert a synergistic effect, thus delaying the ripening process and extending shelf
life of the produce (Akhtar, 2009).
Corrugated boxes and polyethylene sheets have extensive uses in packaging of fresh
produce. Packaging material helps to maintain; modified atmosphere, weight, firmness and
physical integrity of fruits. Many studies have been reported on polyethylene packaging of
12
fruits where PE films reduce weight loss during storage (Sarkar et al., 1997). Since the
packaging films are not completely impermeable; hence, gas and water vapor exchange
depends on the strength or thickness of the film, the temperature and the difference in the
pressure of gases in and outside of the film (Anon, 2008). It is necessary to select proper
packaging material that is suitable for particular fruit, since physiological responses of each
fruit vary to different environmental stress.
Chamara et al. (2000) performed packaging of banana under modified atmosphere in
low density polyethylene (LDP) bags, with and without ethylene scavengers. He reported 24
days shelf life increase by LDP alone. Jiang et al. (1999) reported effective packaging of
banana with polyethylene in combination with 1-MCP. Longest storage (58 days) was
achieved with sealed polyethylene bags. Kleinhenz et al. (2000) have reported shelf life
extension of Bamboo shoots by packing in low density polyethylene sheets. Furthermore,
packaging also aids in reducing water losses and delay ripening by creating a modified
atmosphere with in the storage environment. Weight loss is indicator of inferior quality and
cause economical loss in the marketing chain. The basis for the present study were the
available scientific evidences of previous work which states that chemical preservatives and
packaging films ameliorate external as well as internal factors and extend shelf life of fruits at
ambient storage. Thus the present endeavor was designed to determine the nutritional and
technological properties of locally grown varieties of apricots to furnish a ready reference
data. It was further aimed to evaluate the effect of chemical treatments (CaCl2 and Salicylic
acid) on storage life of apricots, selection of appropriate packaging material and assessment of
combined effect of chemical treatments and packaging material on postharvest quality
attributes of apricots during ambient storage.
13
Chapter 3
MATERIALS AND METHODS
The current study was designed to characterize common apricot varieties from the Northern
Areas and evaluate the postharvest shelf life of fruit under different treatments. All the
chemicals and reagents of analytical grade were purchased from the sole distributers of Sigma
Aldrich (St. Louis MO), Merck (England) and Oxide (UK). The plan of work was divided in
to three phases.
3.1 PHYSICO-CHEMICAL CHARACTERIZAYION OF APRICOT GENOTYPES
In the first phase, most common apricot varieties in the Northern Areas were analyzed
for their nutritional, functional, technological and sensory properties. Fruits at ripening stage
were harvested from 3 to 5 trees of same the variety during the 2nd week of June 2008. The
samples were immediately shifted to the postharvest laboratory of Food Technology
Department, PMAS, Arid Agriculture University, Rawalpindi. The fruits were washed and
graded to select uniform and blemish free sample for further studies. Technological attributes
were recorded without delay after grading, while remaining samples were freezed for
assessment of physico-chemical characteristics and functional attributes. The fruit volume for
each variety was 10 kg and a composite sample of randomly selected 40 fruits was used for
the determination of each parameter.
13
14
3.2 EFFECT OF POSTHARVEST TREATMENTS ON KEEPING QUALITY OF
APRICOT
In the second phase, the selected variety from phase-1 was investigated for postharvest
shelf life under the effect of postharvest treatments during ambient storage. Fruits from 3-5
trees of the selected variety were harvested at commercial maturity stage during the 2nd week
of June 2009. The fruits were sorted, graded and cleaned for selection of uniform sample for
further treatments. Three different experiments were conducted as under:
3.2.1 Effect of Calcium chloride on Keeping Quality of Apricot
The fruits were divided into five lots and treated by dipping with different
concentrations (1, 2, 3 and 4% w/v) of CaCl2 solution (2 L volume) for 3 minutes at room
temperature, while one set was dipped in distilled water and kept as control. The samples
were air dried and put into corrugated cartons. Sponge cubes of equal size were cut and
dipped into saturated solution of potassium permanganate and placed in the same cartons of
treated samples, sealed and stored at ambient conditions. The following parameters were
analyzed during storage at two day’s intervals.
3.2.2 Effect of Salicylic acid on the Keeping Quality of Apricot
Fruits were treated by dipping in different concentrations of salicylic acid solution (2 L
volume) at room temperature as control, 0.5 mM, 1.0 mM, 1.5 mM, and 2.0 mM. The
experiment was conducted as stated in section 3.2.1
15
3.2.3 Effect of Packaging Material on Keeping Quality of Apricot
Fruits were washed, dried and packed in to varying density polyethylene bags of given
specifications as under. Number of fruits per packaging was 10 to 12 depending on size.
Potassium permanganate dipped sponge cubes (1 No each) were also put in to the bags,
sealed and placed in to cartons for storage at ambient conditions.
The specifications of different packaging films were as under:
i) Common food grade brown paper of 0.06 mm density, ii) Low Density Polyethylene
(LDPE) bags (20 x 30cm) of 0.03 mm thickness and with 0.25% perforations, sealed
leaving 3 inch head space, iii) Medium Density Polyethylene (MDPE) bags (20 x 30cm) of
0.06 mm thickness and 0.25% perforations, sealed leaving 3 inch head space, iv) High
Density Polyethylene (HDPE) bags (20 x 30cm) of 0.09 mm thickness and 0.25%
perforations, sealed leaving 3 inches head space.
3.3 EFFECT OF COMBINE TREATMENT ON KEEPING QUALITY OF
APRICOT
In the third phase of the study, combined effect of chemical treatments and packaging
on the shelf life of apricot at ambient storage was assessed. This phase was comprised of
following treatments:
Control = Dipping in distilled water and Combine treatment = 3% CaCl2 and 2 mM SA +
LDPE. The experiment was carried out as steated in section 3.2.1. Data was recorded on
the following parameters in three replicates at an interval of three days during ambient
storage.
16
3.4 PHYSICO-CHEMICAL PROPERTIES OF APRICOT
3.4.1 Proximate Composition
Following compositional properties of the fruit were analyzed;
3.4.1.1 Moisture content
Moisture content was evaluated by oven drying method according to AOAC (2000),
method No. 984.25. 5 grams of commuted pieces of 10 randomly selected fruits were taken
and properly weighed on an electronic balance (AND Electronic Balance, FX-40, Canada).
The sample was put in a hot air oven at 105±5 oC for subsequent drying till constant weight.
3.4.1.2 Dry matter
Dry matter was determined by hot air oven drying method described by AOAC
(2000), 934.06. Five gram of fruit sample was weighed and put in an oven, evaporated at 105
± 5oC till constant weight.
3.4.1.3 Ash
Ash content of whole fruit was determined by AOAC, (2000). Method No. 940.26.
Five grams of fruit sample was weighed and taken in a porcelain dish. The dish with the
contents was put in an muffle furnace at 100 oC for removal of moisture and the temperature
was gradually increased at 50 oC after every one hour and maintained at 500-550 oC for 4 to 5
hours till the complete burning of contents to white ash. After complete ashing, the dish was
cooled and weighed to determine ash content of percent basis.
17
3.4.1.4 Crude fiber
Crude fiber in apricot fruit was estimated by the standard method of AOAC (2000).
Fruit sample (10 g) was weighed and dried in an oven (65±5 oC) till constant weight. The
dried samples were digested in 1.25 percent sulphuric acid and 1.25 percent sodium hydroxide
solution. The digested sample was washed, dried and then put in a muffle furnace at 500 or
550 oC till white ash and the amount was calculated accordingly.
3.4.1.5 Crude fat
Crude fat was determined Soxhlet extraction method (No. 983.23, AOAC 2000). Ten
gram of dried fruit sample was ground to 2mm seive size. The contents were packed in filter
paper and put in the thimble. A round bottom flask was taken, weighed and extraction was
carried by using hexane (B.P. 40-60 oC) as solvent. The flask containing oil was removed
from the assembly and solvent residues were evaporated on a water bath. The oil content was
calculated on weight differences.
3.4.1.6 Crude protein
Crude protein was estimated by using Kjeldhal apparatus (AOAC, 2000 method No.
920.10). Five gram sample was digested with 30 mL sulphuric acid, 10 g potassium sulphate
and 1 g copper sulphate. The contents were heated to colorless mixture and then cooled. The
obtained contents were again diluted with distilled water and distillation was carried out in a
distillation apparatus by taking 10 mL of 40% NaOH. Ammonia obtained was taken in four
percent solution of boric acid and methyl red was used as indicator. Titration of obtained
distillate was done with 0.1 N sulphuric acid till end point of golden brown color.
18
3.4.1.7 Sugar estimation
Sugar estimation was carried out by Lane and Eynon method as described by AOAC,
(2000), method No. 925.36. Ten gram fruit sample was transferred to a beaker and diluted to
100 mL with hot water. The mixture was mixed thoroughly and to dissolve the contents and
filtered with a cotton cloth in 250 mL volumetric flask. 100 mL of this solution along with 10
mL diluted hydrochloric acid was taken in a conical flask. The contents were boiled for 5
mints, cooled and neutralized with 10 mL NaOH. The volume of the solution was made up to
250 mL in a volumetric flask. Titration was made against Fehling’s solution and amounts
were determined on percent basis.
3.4.2 Mineral Contents
Mineral contents of apricot fruit were estimated according to AOAC ( 2000), method
No. 923-07. Dried sample (0.8-1 g) was ignited at 500 to 550 oC for 6 h, till white ash. The
ash was then dissolved in 5 mL 6 M HCl, dried and then added 7 mL of 0.1 M nitric acid
(HNO3). The sample was diluted to 100 mL with double deionized water (Nielsen,1994). Ca,
Cu, Fe, Mg, Mn, Ni and Zn were determined in atomic absorption spectrophotometer (GBC-
932, Australia), Na and K by flame photometer (Model PFP 7, Jenway® England), while P
was determined by spectrophotometer (Model CE-2021, CECIL Instruments®, England).
3.4.3 Technological Properties
Technological properties were determined immediately after the arrival of fruit in the
laboratory. The following weight and size fractions of apricot fruit were measured according
to Baryeh, (2001).
19
3.4.3.1 Fruit weight
Fruit weight, pulp weight and pit weight in grams was measured with an electronic
balance (FX-40, Canada) by randomly selecting 40 fruits from each variety. In addition to
weight dimensions flesh/ seed ratio was also calculated.
3.4.3.2 Fruit size and shape
Dimensional characteristics of apricot (size and shape) were assessed on randomly
selected 100 fruits for each variety. Different features as fruit length (L), fruit width (W), fruit
thickness (T), surface area (SA) and fruit sphericity (Sph.) were measured by a digital slide
caliper.
3.4.4 Post harvest Quality Attributes
3.4.4.1 Firmness
Fruit firmness was recorded with a Fruit firmness tester (Wagner®, model FT-327)
with 11 mm plunger by following the method of Muzumdar and Majumder (2003). Five fruits
from each treatment were used and five points per fruit were selected to determine the
firmness. The firmness value for each fruit was calculated from the average of five
determinations and expressed in terms of kilogram force (kgf).
3.4.4.2 Weight loss
To assess the percent weight loss, three replicates from each treatment were separately
kept in the same ambient conditions. These samples were evaluated for weight loss at three
days intervals by using the following formula:
20
3.4.4.3 Total soluble solids
Soluble solid contents in apricot fruit were determined with the help of a refractometer
(PAL-3®, ATAGO Japan) following the procedure in AOAC, (2000) method No. 920.151.
Wedge shaped pieces of ten fruits were taken and extracted for a composite juice sample.
Data was recorded for three replications and expressed as oBrix.
3.4.4.4 pH
pH in fruit juice was estimated by a pH meter (Inolab) according to AOAC, (2000)
method No. 981.12. Before taking readings, pH meter was calibrated and electrode was rinsed
and dried for each replication.
3.4.4.5 Titratable acidity
Titratable acidity (TA) in terms of malic acid equivalent in apricot was estimated by
AOAC (2000), method No. 981.12. 10 g pulp was taken from randomly selected 10 fruits,
homogenized and mixed with distilled water (40 mL) and filtered to obtained clear extract. 10
mL aliquot was titrated by using 0.1 N sodium hydroxide solution and adding few drops of
phenolphthalein as indicator till the appearance of light pink color end point. Data was
recorded on three replications and percent titratable acidity was calculated in terms of malic
acid.
3.4.4.6 Ascorbic acid
Ascorbic acid (AA) estimation was carried out by using 2-6 di-chlorophenol indo-
phenol dye as described in AOAC, (2000), method No. 967.21. Ten gram fruit sample was
transferred to a beaker and volume was made up to 100 mL with 3% phosphoric acid and then
21
filtered. 10 mL of the above filtrate was titrated with standard dye and the amount of ascorbic
acid was calculated as mg/ 100g.
3.4.4.7 Total phenolic contents
Total phenolic contents (TPC) were estimated by Folin-Ciocalteu (FC) method as
reported by Sponas and Wrolstad (1990). Randomly selected apricots were homogenized to
prepare a representative sample. Five gram representative sample was diluted with 30 mL
deionized water, clarified followed by centrifugation for 15 minutes at 10000 g. The clarified
extract was then filtered through a membrane filter (0.45 mm). From this filtrate 0.5 mL was
taken in a 25 mL volumetric flask. To the same flask 5 mL of 0.2 N FC reagent and 4 mL of
sodium carbonate solution (7.5%) was added and volume made up to the mark with deionized
water. This content was incubated at 50 oC for 8 minutes and absorbance was recorded at 765
nm by using a Spectrophotometer (CE-2021, CECIL® Instruments, England). TPC were
calculated as milligram GAE per 100 g on dry weight basis from a calibration curve using
gallic acid as reference compound.
3.4.4.8 Total carotenoids
Total carotenoids (TC) of apricot were estimated by following the procedure described
by Rodriguez-Amaya (1999). Carotenoids were extracted by taking 5 g homogenized sample
with a 100 mL methanol and petroleum ether (1:9 v/v), and then poured in to a separating
funnel. The layer of petroleum ether was separated through sodium sulpahte and methanolic
extract was taken in a 100 mL volumetric flaks and volume made up. Carotenoid contents
were estimated spectrophotometerically at 450 nm wave length and expressed as milligrams
per 100 g of β-carotene on dry weight basis.
22
3.4.4.9 Antioxidant activity
Antioxidant activity (AoA) of apricot sample was estimated in terms of DPPH (2, 2
diphenyl 1 pecrylehydrazyl) free radical scavenging capacity according to Brand-Williams et
al. (1995). Five gram of frozen tissues were taken, homogenized and extracted with methanol
(10 mL) for two hours in triplicate. A reaction mixture was prepared by taking 0.1 mL of the
above extract in test tube and added 3.9 mL of DPPH solution (6 × 10–5 mol/L). The mixtures
were allowed to stand for thirty minutes at room temperature and absorbance was recorded at
517 nm (UV-Spectrophotometer, UNICO 2100® Series Japan) against blank. Fresh DPPH
solution was prepared daily and kept in dark between the readings. Similarly, blank samples
were prepared from methanol and DPPH by taking the same concentrations as mentioned in
sample preparation. The valuses were calculated as percent antioxidant activity.
3.4.4.10 Extraction of enzymes
Enzyme extraction was performed according to the procedure described by Abbasi et
al., (1998) with minor alterations. 5 gram of frozen apricot pulp of 10 randomly selected fruits
from each replication was taken and pasted with mortar and pestle. A suspension was made
with 15 mL of 100 mM KH2PO4 buffer of pH 7.8 with Triton X-100 (0.5% v/v) and 1 g
polyvinyl polypyrolidone (PVPP). The above homogenate was then centrifuged at 18000 x g
for 30 minutes at 4 oC. The supernatant was separated, stored at -2 oC and triplicate data was
recorded for each treatment.
3.4.4.11 Total soluble protein
Soluble proteins were estimated by using bovine serum albumin (BSA) as reference
according to Bradford (1976). The basic principle of this method is protein binding to the dye
23
(coomassie blue G-250). When the protein binds to the dye a shift in the absorbance of dye is
caused up to a maximum of 465-495 nm. For the preparation of protein reagent, 100 mg
coomassie blue dye was dissolved in 50 mL ethanol (95%) 100 mL phosphoric acid (85%)
and a final volume of 1 liter was made with distilled water. Measurement of protein
concentration of sample was under taken by taking 100 µl of supernatant in 5mL protein
reagent. A standard solution of 1mg/ mL BSA was prepared and used to determine protein
contents. A series of protein solutions with concentrations of 10-100 µg with 5 mL protein
reagent were taken to plot standard curves of protein weight against their corresponding
absorbance. Cavettes of 3 mL sample were let stand for two minutes the absorbance was
measured against reagent blank containing 0.1 mL buffer with 5 mL protein reagent at a wave
length of 595 in spectrophotometer. The contents were expressed as mg of protein per g of
fresh sample weight.
3.4.4.12 Polyphenol oxidase assay
Polyphenol oxidase (PPO) was determined based on catichol oxidation according to
Jiang and Fu (1998). A reaction mixture of 2 mL total volume was prepared by taking 1.3 mL
(0.05 M) potassium phosphate buffer (pH 7.5), 0.2 mL (0.2 M) catichol and 0.5 mL enzyme
extract in test tube. The contents were incubated at 30 oC for 5 mints. Absorbance was
measured at 420 nm in a UV-visible spectrophotometer (CE-2021, 2000 series, CECIL
Instruments England). Enzyme activity was determined based on change in absorbance over a
period of 1 minute and expressed as U/g (enzyme unit per gram of protein on fresh weight
basis).
3.4.4.13 Peroxidase assay
Peroxidase activity (POD) in apricot fruit was estimated by using guaiacol as substrate
accoding to Abbasi et al. (1998) with some modifications. A reaction mixture of 2.5 mL total
24
volume was prepared with 2.3 mL of sodium acetate buffer (pH 6.0), 0.05 mL of substrate
(0.1% guaiacol v/v), 0.1 mL of 0.1% H2O2 (v/v) and 0.05 mL of enzyme extract. Activity was
calculated at 470 nm on the basis of change in optical density over a 1 minute period and
expressed as units/ gram of protein on fresh weight basis.
3.4.4.14 Catalase assay
Catalase activity (CAT) was estimated by using the method of Abbasi et al. (1998). To
complete the reaction two solutions were used as buffer A and B. The buffer A consist of 2.7
mL (15 M) potassium phosphate buffer (pH 7.0), and buffer B consist of 2.7 mL 12.5 mM
H2O2 in 15 M KPO4 (pH 7.0). To each cavettes containing buffer A and B, 300 µl enzyme
extract was added and held in dark. Optical density at 45 seconds and 60 seconds was
recorded and time starting from the addition of enzyme extract to the cavettes. The difference
in the optical density of two time intervals as stated above were noted to calculate enzyme
activity and expressed as units per gram of protein on fresh weight basis.
3.4.4.15 Total viable count
Total viable count (TVC) was carried out by serial dilution agar plate method
(Cappuccino and Sherman 1996). Total viable count was expressed in term of colony forming
units (log10 cfu/mL of sample). Serial dilutions were made in the ratio of 1:10 and 1 mL of
each dilution was poured in to the plates of nutrient agar and incubation was carried out at 28-
30 oC for 24 hours.
25
3.4.4.16 Total fungal count
Total fungal count (TFC) was carried out by the method described by El-Nagerabi and
El-Shafie (2000) with some modification. Each sample of fruit (25 g) was combined in to 225 mL
of 0.85% sterile solution of sodium chloride in a polyethylene bag and pummeled for two minutes
with a stomacher. The obtained aliquot was used for serial dilutions for determination of total fungal
count. 0.2 mL from each dilution was poured on potato-dextrose agar (PDA) and incubated at
room temperature for three days. The colonies of fungi, developed around the sample were
examined, counted and data presented as colony forming units (log cfu) per mL of sample.
3.4.5 Sensory Attributes
Sensory evaluation of apricot fruit was carried out to determine consumer preference
according to Larmond (1997) on 9 point hedonic scale by panel of five trained judges. Fruits
of same maturity level were used to eliminate any bias. The key features of the scale are:
9 = Like extremely, 8 = Like very much, 7 = Like moderately, 6 = Like slightly, 5 = Neither
like nor dislike, 4 = Dislike slightly, 3 = Dislike moderately, 2 = Dislike very much, 1 =
Dislike extremely
3.4.6 Statistical Analysis
One way analysis of variance (ANOVA) considering varieties as source of variance
was used in the first phase, while two way ANOVA was used in the second and third phase.
Means of three replications were compared by Duncan Multiple Range Test (DMRT) at p ≥ F
0.05 (Steel et al., 1997) using MSTAT-C soft ware (Michigan State University 1991).
26
Chapter 4
RESULTS AND DISCUSSION
In the first phase of the study, physico-chemical, functional and technological
characterization of twelve commonly grown varieties of apricot in the Northern Areas was
carried out. The results reveald Habi, Khakhas, Alman and Halman as prominent varieties
regarding proximate composition, Jahingir superior in mineral contents, while, Mirmalik as
the leading variety in technological traits.
4.1 PHYSICO-CHEMICAL ATTRIBUTES OF APRICOT
4.1.1 Proximate Composition of Apricot
The proximate composition in terms of dry matter, ash, crude fiber, fat, protein and
sugars showed significant differences (p ≥ F 0.05) among the tested cultivars (Table 1). Dry
matter ranged from 14.0 to 21.48 g/100g on fresh weight basis. The highest dry matter was
found in Jahangir, Khakhas, Alman and Halman, while the lowest was observed in Yagoo.
Dry matter is an important character in determining the suitability of a variety for its value
addition and processing. Low dry matter varieties are susceptible to handling and
transportation; hence higher postharvest losses occur during marketing. Furthermore, high
moisture levels also permit increased chemical and microbial activities that further limit the
shelf life and leads to complete senescence and spoilage. Similarly, dry matter is instrumental
in selecting apricots for dry products or fresh consumption. Varieties carrying higher moisture
26
27
Table 1. Proximate composition of the apricot varieties expressed on dry weight basis suggesting that the Habi, Jahangir, and Khakhas had greater dry matter, ash and reducing sugars compared to the other genotypes
Note: Means in a column with different letter(s) are significant at p ≥ F 0.05.
Varieties Dry matter Ash Crude fiber Crude fat Crude protein
Reducing sugars
Non-reducing sugars
Total sugars
---------------------------------------------------------------%---------------------------------------------------------------- Alman 19.10b 10.55d 11.38cd 2.47f 6.18ef 16.73d 47.13b 63.89bc
Habi 21.20a 12.10a 11.93bc 2.94cd 6.54d 21.38a 43.55d 64.74ab
Khakhas 20.99a 11.61b 12.23b 2.18i 6.18ef 14.95g 47.54b 62.49de
Mirmalik 14.73fg 10.92c 13.60a 2.10j 7.61c 15.96de 40.82f 56.78g
Neeli 15.00f 9.45h 11.85bc 3.00c 8.25b 15.32g 45.95c 61.27ef
Shai 15.50ef 9.61f 12.24b 2.25h 8.70a 15.10fg 41.98e 57.08g
Halman 18.00c 9.55g 10.27e 2.88d 6.10f 15.87ef 49.59a 65.23a
Jahangir 21.48a 10.59d 11.35d 2.54e 6.32e 19.73b 43.55d 63.31cd
Margulam 16.00e 10.00e 11.86bc 2.94cd 6.25ef 13.19h 47.31b 60.57f
Shakanda 16.87d 8.48i 9.66ef 4.26a 6.64d 18.63c 45.30c 64.19bc
Shirini 15.00f 8.21j 9.42f 3.57b 5.52g 19.76b 43.43d 63.44cd
Yagoo 14.00g 8.20j 11.13d 2.33g 4.86h 16.00de 46.00c 61.99e
LSD 0.82 0.05 0.62 0.07 0.16 0.80 0.88 1.24
28
levels are considered suitable for fresh consumption and processing in to juices, while low
moisture fruit best fits for dehydration and drying. Previously, Akin et al., (2008) and
Haciseferogullari et al., (2007) have reported high dry matter contents of apricots and
observed variation in contents among the fruits of different regions. Ash content, crude fiber,
fat protein and sugars were evaluated on dry weight basis, since moisture influence the
composition of different constituents. Analytical results regarding ash content ranged from
8.20 to 12.10% among the genotypes and the differences were significant (p ≥ F 0.05) except
for Jahangir, Alman and Shirini, Yago. Habi was rich in terms of percent ash followed by
Khakhas and Mirmalik, while, the lowest was found in Shakanda, Shirini and Yagoo. Ash
content is the indicator of minerals present in the commodity and according to our findings
Habi was the leading variety.
Crude fiber contents in the evaluated varieties found in the range of 9.42-13.60%
(Table 1). Mirmalik was the leading genotype regarding crude fiber contents followed by
Shai, Khakhas, Habi, Marghulam, Neeli, Alman, Jahangir, Yagoo, Halman, Shakanda and the
lowest was observed in Shirini. A partially significancant (p ≥ F 0.05) pattern was observed
for fiber contents among the evaluated varieties. These differences might be due to genetic
variations of the tested samples (Ahmadi et al., 2008). Previously fiber content in fresh
apricot has been reported in the range of 1.5-2.4 g/100g (Haciseferogullari et al., 2007).
Owais, (2007) has reported lower concentrations of fiber in Jordan apricots. It has been
established that geographical origin, genotype, cultivation practices and climatic conditions
may influence the composition of fruits (Munzuroglu et al., 2003; Leccses et al., 2007).
Although fiber has no energy value, however, it is important in providing roughage and
improving bowl movement (Akin et al., 2008); thus improve overall gut environment and
29
prevent constipation (Tamura et al., 2011). It also maintains blood sugar levels, reduce body
weight, absorb extra fat from body and thus vital in maintaining good health (Lairon, 1990).
Crude fat contents were established from 2.10-4.26% among the cultivars (Table 1)
and the results were significant (p ≥ F 0.05). Shakanda was the rich regarding percent fat
followed by Shirini, Neeli and Halman, Habi, Marghulam, Jangir, Alman, Yagoo, Shai and
Khakhas while minimum amount was found for Mirmalik. Apricot flesh is low in fat;
however it contains important unsaturated fatty acids which have high nutritional value and
health benefits (USDA, 2005). Previously Chauhan et al. (2001) and Owais, (2007) have also
established fat composition of apricot fruits. Those results were found to be in close
agreement with the findings of present study.
Crude protein was recorded in the range of 4.86-8.70% (Table 1). The results were
partially significant (p ≥ F 0.05) among the varieties. High protein content was found in Shai
followed by Neeli, Mirmalik, Shakanda, Habi, Jahangir, Marghulam, Alman, Khakhas,
Halman, Shirini and Yagoo respectively. Protein content in apricot fruit is found in minute
quantities; however, their role from nutritional point of view is of significance. Proteins
supply essential amino acids which are important part of nucleic acid and many enzyme
systems in the body; hence crucial in performing different physiological and biochemical
functions (Sochor et al., 2011). The findings of current work are closely related to the
previous reports by Owais, (2007) and Chauhan et al. (2001) regarding the protein content of
apricot.
The data obtained for sugars indicated partially significant (p ≥ F 0.05) patterns among
30
different sugars (reducing, non-reducing and total) in the tested varieties (Table 1). The range
found for reducing sugars was 13.19-21.38% and the results were significant except for
Jahangir and Shirini. High reducing sugar was observed in Habi followed by Sirini, Jahangir,
Shakanda and lowest in Marghulam. Non-reducing sugars were ranged between 40.82 to
49.59%. Higher contents were obsered in Halman followed by Khakhas, Marghulam, Alman,
Yagoo, Neeli, Sakanda, Habi, Jahangir, Shirini, Shai and lowest in Mirmalik. The data
regarding total sugars revealed high amounts for Halman followed by Habi, Shakanda,
Alman, Shirini, Jahangir, Khakhas, Yagoo, Neeli, Marghulam, Shai and the minimum was
observed in Mirmalik. All the values were significant (p ≥ F 0.05) except for Shai and
Mirmalik.
Sugars determine consumer acceptability of a fruit and also indicators of maturity.
They provide instant energy to the body for the performance of various activities. Apricot is
rich in sugars and the concentration increase towards ripening. Higher concentrations at full
ripening stage results from breakdown of complex carbohydrates in to simpler sugars. Reports
have established increased sugar level in the later stages of ripening in fruits (Aydin and
Kadioglu, 2001; Var and Ayaz, 2004). Due to elevated sugar levels apricot is considered as a
high energy fruit. The results were also comparable with earlier studies by Leccese et al.
(2010), Haciseferogullari et al. (2007), Chauhan et al. (2001) and Gurrieri et al. (2001). A
variation was noted in sugar content among the tested genotypes that might be due to genetic
variation in the samples. Leccese et al. (2007) and Akbulut and Artik, (2002) have reported
differences in composition due to geographical origin, cultivar and stage of ripening.
4.1.2 Chemical and Functional Properties of Apricot
Total soluble solids ranged from 12.73 to 23.00 OBrix and varied significantly (p ≥ F
0.05) among the tested varieties (Table 1). Highest TSS was found for Halman that was
31
followed by Shakanda, Habi, Alman, Shirini, Khakhas . TSS content of fruits is an indicator
of ripening process and used as a tool in determining the harvesting time (Crisosto and Kader,
1999). It also represents the sugar content and hence considered as a quality parameter
(Gurrieri et al., 2001). Furthermore TSS also determines the consumer acceptance of fresh
commodities (Infante et al., 2008). The soluble solid contents established in the present study
were in consistent with the earlier investigations by Milosevic et al. (2010) and
Haciseferogulari et al. (2007).
pH values for different cultivars in the current study ranged from 3.80-5.53 (Table 2).
The difference in pH was significant (p ≥ F 0.05) among the tested samples except for Habi
and Shirini. Halman was dominating regarding pH among the varieties, while, the lowest
value was obtained for Mirmalik. Chemically, pH represents the hydrogen ion concentration
of a commodity and the values decrease when the fruit ripens. Studies on apricot fruit by
many researchers (Mratinic et al., 2011; Owais, 2007; Chauhan et al., 2001) have agreement
with the outcomes of the current investigation. The quality characters of fruits however differ
due to variations in pomological traits (Milosevic et al., 2010; Crossa-Raynaud and
Audargon, 1991) and agro-ecological factors (Guerririo, et al., 2006). Titratable acidity was
higher in Marghulam followed by Mirmalik, Khakhas, Jahangir, Yagoo, Neeli, Alman, Habi,
Shai and Halman, while, the minimum was observed in Shakanda and Shirini with significant
differences (p ≥ F 0.05). Titratable acidity shows the organic acid concentration. Apricot
carries malic acid as the major organic acid followed by citric acid (Gurrieri et al., 2001)
32
Table 2. Chemical and functional composition expressed on dry weight basis indicating Halman variety having maximum total soluble
solids, total phenolics, total carotenoids and antioxidant activity among the tested cultivars
Varieties Total soluble
solids*
pH Titrable
acidity
Ascorbic acid Total phenolic
contents*
Total carotenoids* Antioxidant
activity
OBrix % ------------------------mg/100g---------------------- % Alman 19.00d 4.70e 3.60d 77.76f 6530b 17.03h 64.50bc
Habi 20.00c 5.20c 3.15e 79.27e 7310a 18.13g 82.33a
Khakhas 18.00ef 4.10i 4.09b 86.26d 6305bc 16.12h 62.19cd
Mirmalik 12.67i 3.80k 4.14b 86.60d 6012cd 14.50i 58.42ef
Neeli 12.73i 4.00j 3.60d 90.94b 4591fg 12.23j 55.70f
Shai 14.40h 4.51g 2.90f 67.39i 4894ef 10.12k 56.77f
Halman 23.00a 5.53a 2.38g 76.44g 7109a 50.12a 79.43a
Jahngir 17.30f 4.60f 3.96c 89.34c 5211e 40.54c 61.02de
Marghulam 14.03h 4.80d 4.62a 96.87a 4376g 19.61f 32.44h
Shakanda 21.97b 5.40b 1.78h 56.44j 5722d 46.07b 66.76b
Shirini 18.20de 5.20c 1.74h 67.71i 5115e 39.45d 60.85de
Yagoo 16.20g 4.20h 3.67d 71.27h 4612fg 36.41e 39.71g
LSD 0.85 0.06 0.09 1.20 334.56 0.98 3.34
Legend: *, Total soluble solids were assessed in fresh juice, while total phenolic contes expressed as gallic acid equivalent(GAE) and total carotenoids as ß-carotene equivalent Note: Means in a column with different letter(s) are significant at p ≥ F 0.05.
33
beside minute amounts of tartaric, oxalic, succinic and fumaric acid (Hasib et al. 2002). Acid
composition is also an important attribute in determining the taste of the commodity. A
balanced composition of organic acids, sugars and volatile compounds is responsible for
exceptional flavor of fruit (Baldwin et al., 2000). Furthermore organic acids are required in
minute quantities and play their role in the fluid systems of body in maintaining acid base
balance (Hasib et al., 2002).
Ascorbic acid contents revealed significant differences (p ≥ F 0.05) among the tested
genotypes of apricot (Table 2). A non-significant trend was noticed between Mirmalik and
Khakhas followed by Shirini and Shai. Marghulam was leading variety followed by Neeli,
Jahangir, Mirmalik, Khakhas, Habi, Alman, Halman, Yagoo, Shirini, Shai and least
concentration observed in Shakanda. Overall results demonstrated a rich ascorbic acid profile
in all cultivars and the established range was 56.44 to 96.87 mg/100g on dry weight basis.
Ascorbic acid is the most important water soluble vitamin supplied by fruits and vegetables
(Hernandez et al., 2004). It is an indicator of postharvest fruit quality, since increase in AA
indicates continual ripening while a decrease is the indication of senescent stage (Esteves et
al., 1984). As an antioxidant it performs numerous roles in the body (Suh, 2002; Berger et al.,
1997). It has great significance due to its high bioavailability and recognized as a vital
indicator of postharvest shelf life of fresh fruits (Pila et al., 2010). Ascorbic acid is also
considered as an important antioxidant and free radical scavenger. Available literature
reflected apricot as a rich source of ascorbic acid among different fruits. Akin et al. (2008)
have narrated higher contents of ascorbic acid in apricot fruit from Turkey (20.6-96.80
mg/100g DW). Similarly, Chauhan et al. (2001) and Thompson and Trenerry (1995) have
also established good contents of ascorbic acid i.e. 5-19.00 mg/100g and 10 mg/100g in
34
apricot pulp respectively. These results are also in close agreement with previous work of
Haciseferogullari et al. (2007) on apricot. It has been further shown that genetic variations,
geography, cultural practices and climatic conditions may influence fruit composition
(Gurerrio et al., 2010).
The varieties under investigation showed statistically significant (p ≥ F 0.05) amounts
of total phenolic contents (Table 2). Total phenolic contents were established in the range of
4376 to 7310 mg GAE/100g among the tested genotypes. Habi and Halman were leading with
higher amounts of phenolic compounds followed by Alman, Khakhas, Mirmalik, Shakanda,
Jahangir, Shirini, Shai, Yagoo, Neeli and the least content was observed in Marghulam.
Phenolic compounds (phenolic acids and Flavonoids) are important plant chemicals and carry
a variety of functions in the living systems. These are vital contributors (color, astringency,
bitterness) towards sensory quality of fruits and hence attracted the attention of researchers in
the recent years (Hamauzu, 2006). Apricot fruits have been reported having varying amounts
of phenolic compounds (Leecesse et al., 2010; Lecesse et al., 2007; Akin et al., 2008) and the
compositions ranges from 50-1600.00 mg/ 100g on fresh weight basis (Akbulut and Artik,
2002; Sochor et al., 2010; Kalyoncu et al., 2009; Ruiz et al., 2005). Previously, phenolic
content of Turkish apricots (4233.70-8180.49 mg GAE/ 100g) have been reported by Akin et
al. (2008) on dry weight basis. The results of present study with comparison to previous
literature suggest rich phenolic composition of apricot from this region. Scalzo et al. (2005),
Ruiz et al. (2005), Akbulut and Artik, (2002) have established TPC concentrations from 214-
266 mg/ L, 326-1600 mg GAE/ 100g, 769-1283 mg GAE/ 100g respectively in different
apricot genotypes on fresh weight basis. Phenolic composition is affected by stage of maturity
and the concentration increases towards ripening (Lecesse et al., 2010). In contrast, some
studies have shown higher contents of phenolics in unripe fruit and decrease in some
constituents with advanced maturity stage (Dragovic-Uzlac et al., 2007). It has been shown
35
that several factors affect the compositions of fruits and vegetables i.e. harvesting stage,
cultural practices, genotype and climate of the region (Milosevic et al., 2010; Guerririo et al.,
2006).
Total carotenoid (TC) composition of apricot was determined by using β-carotene as
standard. The data revealed carotenoid range from 10.12 to 50.12 mg/100g in the varieties
under investigation (Table 2). A significant pattern (p ≥ F 0.05) was observed among the
genotypes except Alman and Khakhas. Higher TC concentration was observed in Halman
followed by Shakanda, Jahangir, Shirini, Yagoo, Marghulam, Habi, Alman, Khakhas,
Mirmalik, Neeli and the lowest in Shai. Apricot contains fairly higher amounts of carotenoids.
Previously, it has been reported that ß-carotene is the predominant carotenoids in apricot
representing 50 % of total concentration (Radi et al., 2004). Akin et al. (2008) investigated
the carotenoids content in terms of ß-carotene of Malatya apricots and found 14.83-91.89
mg/100g DW. Dragovic-Uzlac et al. (2007) have also reported similar results for three
cultivars of apricot from Croatia. Carotenoids are pigment compounds responsible for giving
different colors to fruits, vegetables and flowers (Rao and Rao, 2007). They act as
antioxidants and thus prevent many degenerative disorders caused by free radicals in the body
(Bramley, 2003). Previously reported range of carotenoids in apricots is 2.00-20.77 mg/ 100g
Beta carotene (De Regal et al., 2000; Ruiz et al., 2008), however the contents were high in the
present study. It has been established that carotenoids concentration increases with the
advancement in maturity and higher accumulation can be observed at full ripening. However
the contents decrease in later stages of senescence due metabolic activities (Khachik et al.,
2002). The composition may be however affected by agro-ecology and method of cultivation
(Akinci et al., 2004). Antioxidant capacity in apricot varieties in terms of DPPH free radical
scavenging activity ranged from 32.44 to 82.33%. The results were partially significant at p <
0.05 with some non-significant patterns as indicated in table 2. Habi was dominating in
36
antioxidant activity followed by Halman (with statistically same levels), Shakanda, Alman,
Khakhas, Jahangir, Shirini, Mirmalik, Shai, Neeli, Yagoo and Marghulam respectively.
Apricot fruit contains a variety of bioactive compounds (phytochemicals) having significant
antioxidant properties (Lecesse et al., 2010).
Antioxidant compounds fast becoming a quality index in fruits and vegetable, since
they indicate the free radical scavenging potential of the commodity (Lecesse et al., 2007).
Higher antioxidant activity was observed in the varieties with increased levels of total
phenolics in the present study. Early studies by Andlauer and Faust (1998) and Vinson et al.
(1998) have established higher antioxidant potential in foods with numerous phyto-nutrients.
Our studies are also in line with previous investigations that high phenolic concentrations are
responsible for increased antioxidant capacity in apricot (Durmaz and Alpaslan, 2007).
Drogoudi et al. (2008) have established a strong correlation among phenolics concentration
and antiox
