View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Repository@USM ASSESSMENT OF ANTIOXIDANT POTENTIAL OF DATE (PHOENIX DACTYLIFERA) FRUITS FROM IRAN, EFFECT OF COLD STORAGE AND ADDITION TO MINCED CHICKEN MEAT by FOROOGH BIGLARI UNIVERSITI SAINS MALAYSIA Thesis submitted in fulfillment of the requirements for the degree of Master of Science JANUARY 2009 ACKNOWLEDGMENT Acknowledging the dedicated efforts of those who gave me support and made my master studies a great experience, is a great pleasure for me. Praise and thanks to Allah for granting me grace, wisdom, and the opportunity to pursue the master study program. I would like to express my grateful appreciation to Associate Prof. Dr. Azhar Mat Easa, my supervisor for his great leadership and valuable comments during my entire studies. I would also like to express my sincere gratitude to Dr. Abbas F.M. Al-Karkhi who gave me guidance for the completion of my master thesis. I particularly want to thank Professor Baharodhin Saad for his patience and guidance. I also want to thank Professor Dr. Rahmah Noordin for her precious advice. I am also grateful to my friends, Ms Sabiha, Yanti, Maizura, Rodiah, and Mohammad who helped me tremendously during my experimental work. Further, I would like to express my special thanks to Mrs. Beth Thompson for her advice in English phrasing. Greatest thanks to the School of Industrial Technology and University Sains Malaysia under the student assistant support scheme for their financial assistance. Last but not least a special word of gratitude to my wonderful family; I thank my parents and my brother, Associate Prof. Dr. Faridreza Biglari for their unfailing encouragement and my beloved husband, Hamidreza, for his moral and unconditional support and my daughter’s encouragement which enabled me to complete my master project. FOROOGH BIGLARI August 2008 ii TABLE OF CONTENT PAGE ACKNOWLEGEMENT ii TABLE OF CONTENT iii LIST OF TABLES viii LIST OF FIGURES x LIST OF PLATES xii LIST OF ABBREVIATIONS/SYMBOLS xiii ABSTRAK xvi ABSTRACT xviii CHAPTER 1: INTRODUCTION 1 1.1 Background and Rationale 1 1.2 Hypotheses and research questions 6 1.3 Objectives 7 1.4 Thesis Outline 8 CHAPTER 2: LITERATURE REVIEW 10 2.1 Date as the oldest cultivated plant in the Middle East 10 2.1.1 History of date fruits (Phoenix dactylifera) 10 2.1.2 Productions 10 2.1.3 Dates in Iran 11 2.1.4 Stages of date ripening 15 2.1.5 Storage of date 16 2.1.6 Chemical composition of date fruit 17 iii 2.1.6.1 Moisture content 17 2.1.6.2 Sugars 19 2.1.6.3 Proteins and Fats 20 2.1.6.4 Crude fibres (non-soluble solids) 21 2.1.6.5 Vitamins and Minerals 22 2.1.6.6 Enzymes 23 2.1.6.7 Other chemical substances 25 2.1.6.7.1 Polyphenols 25 2.1.6.7.2 Organic acids 27 2.1.6.7.3 Others 27 2.2 Antioxidant activity 29 2.2.1 Antioxidant activity in dates 30 2.2.2 Antioxidant activity in other fruits 31 2.2.3 Antioxidant activity assays 34 2.2.3.1 DPPH 34 2.2.3.2 ABTS 35 2.2.3.3 FRAP 37 2.3 Effect of heat or cold storage on phenolic compound 38 2.3.1 Phenolic compound 38 2.3.2 Changes of total phenolic compounds during storage 40 2.4 Application of antioxidant activity and phenolic compound in food to 44 retard lipid oxidation. 2.4.1 Lipid oxidation 44 2.4.2 Chicken meat 45 2.4.3 Inhibition of lipid oxidation in food by using of natural antioxidant 46 and phenolic compound. iv 2.5 Statistical analyses 49 2.5.1 Multivariate analysis of variance (MANOVA) 49 2.5.2 Discriminant function 49 2.5.3 Principal component analysis (PCA) 50 2.5.4 Cluster analysis (CA) 51 CHAPTER 3: MATERIALS AND METHODS 52 3.1 Antioxidant content of eight types of Iranian date fruits 52 3.1.1 Plant material 52 3.1.2 Chemicals and reagents 54 3.1.3 Extraction 54 3.1.4 Measurement of antioxidant activity 56 3.1.4.1 ABTS assay 56 3.1.4.1.1 Determination of TEAC value 59 3.1.4.2 FRAP assay 63 3.1.5 Total phenolic content 64 3.1.6 Total flavonoid content 66 3.2 Effect of long term cold storage on antioxidant compounds in dates 67 (Phoenix dactylifera). 3.2.1 Plant material 67 3.2.2 Chemicals and reagents 67 3.2.3 Storage of dates 67 3.2.4 Total phenolic (TPC) and total flavonoid content (TFC) 68 analysis v 3.3 Application of aqueous extracts of date to inhibit lipid oxidation in 68 chilled minced chicken meat (MCM). 3.3.1 Plant material and extraction 68 3.3.2 Chemicals and reagents 69 3.3.3 Meat samples 69 3.3.4 Proximate composition 72 3.3.5 pH measurements 72 3.3.6 Measurement of peroxide value by iodometric titration 73 3.3.6.1 Preparation and standardization of sodium thiosulfate 74 solution. 3.3.6.1.1 Standardize solution 78 3.3.6.2 Saturated potassium iodide solution 79 3.3.6.3 Starch indicator solution, 1 % (w/v) 79 3.3.7 Determination of 2-thiobarbituric acid reactive substances as an 80 index of lipid oxidation. 3.3.7.1 Preparation of TBA solution 82 3.3.7.2 Determination of TBA 82 3.4 Statistical analyses 84 85 CHAPTER 4: Results and discussions 4.1 Antioxidant content of eight types Iranian date fruits 85 4.1.1 Introduction 85 4.1.2 TEAC and FRAP result 86 4.1.2.1 Information processing and data presentation 90 vi 4.1.3 Total phenolic content (TPC) of eight types of Iranian date fruits. 91 4.1.4 Total flavonoid content (TFC) of eight types of Iranian date fruits. 92 4.1.5 Percentage of inhibition 96 4.1.6 Statistical analysis of AA, TPC, and TFC of eight selected DPF 97 4.1.6.1 Relationship between AA, TPC, and TFC 97 4.1.6.2 Descriptive statistics 99 4.1.6.3 Multivariate analysis 100 4.1.6.4 Discriminant function 100 4.1.6.5 Principal component analysis (PCA) 102 4.2 Effect of long term cold storage on antioxidant compounds in dates. 105 4.3 The effects of aqueous extracts of date palm fruits on lipid oxidation of 108 chilled minced chicken meat. 4.3.1 Proximate analysis 108 4.3.2 pH 109 4.3.3 The effect of aqueous date palm fruit extract on primary lipid 111 oxidation (Peroxide value). 4.3.4 The effect of aqueous date palm fruit extract on secondary lipid 115 oxidation (TBARS values). 4.3.5 Statistical analysis of pH, PV, and TBA 122 CHAPTER 5: GENERAL CONCLUSION AND RECOMMENDATIONS 132 5.1 General conclusions 132 5.2 Recommendations for future study 133 REFERENCES 135 APPENDICE 167 LIST OF PUBLICATION 175 vii viii LIST OF TABLES Table Page 2.1 Top ten dates producers in 2005 (1000 tones). 11 2.2 The main producing areas in Iran. 13 2.3 Number of date varieties described per country. 14 2.4 Some variety of Iranian dates. 14 2.5 Water content of a date fruit during its maturation from 15 Khalal to Tamar stage. 2.6 Vitamin content of Dates. 23 4.1 Antioxidant activity of different date varieties from Iran 167 (based on fresh weight). 4.2 Antioxidant activity of different date varieties from Iran 88 (based on dry weight). 4.3 Total phenolic content and total flavonoid of different date 93 varieties from Iran (based on dry weight). 4.4 Linear correlation coefficient matrix for selected 167 parameters in dates. 4.5 Descriptive statistics including minimum, maximum, 168 mean and standard deviation for selected parameters in dates. 4.6 Multivariate analysis of variance (MANOVA) for eight 169 types of dates. 4.7 Wilks’ Lambda for testing discriminant function validity. 169 viii 4.8 Classification results for discriminant analysis of all types 169 of dates. 4.9 Extracted values of PCA for all types of dates. 170 4.10 Descriptive statistics of dates before and after storage at 170 4°C for 6 months followed by 7 days storage at 18°C. 4.11 Proximate composition of dates (Bam and Kharak). 109 4.12 The results of experimental design for three factors. 171 4.13 The results of ANOVA for pH, PV, and TBA. 173 4.14 The results of Tukey’s test for pH, PV, and TBA at 174 different concentration and storage time. ix LIST OF FIGURES Figure Page 3.1 Extraction process and analysis of phenolic compound from date 55 fruits. 3.2 Chemical structure of ABTS•+ radical cation. 56 3.3 The basis of the ABTS•+ radical cation assay for measurement total 57 antioxidant activity. 3.4 Design of experiment based on three factor, types of dates (two 71 types), concentration of antioxidant extract (three levels), and storage time (five times) on three responses pH, PV, and TBA. 3.5 Spectrophotometric analysis of 0.01 N iodine (dotted line) and 74 iodine-starch complex (solid line) from 400 nm to 900 nm. Absorption spectrum indicates the absorption maximum of iodine- starch complex is 563 nm. 3.6 Malondialdehyde formation pathway from peroxyl radical of 81 triunsaturated C18 fatty acid (a) and formation of TBA chromophore from TBA and malondialdehyde (b).