Investigating carotenoid loss after drying and storage of

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ABBREVIATIONS ABTS 2,2'-azino-bis 3ethylbenzthiazoline-6-sulphonic acid LA linoleic acid aw Water activity LOX lipoxygenase BET Brunauer-Emmett-Teller LPDE Low density polythene CIAT International Center for Tropical Agriculture, Colombia VI MTBE Methyl-ter-butyl-ether CIELAB CIE 1976 (L*, a*, b*) color space NARL National Agricultural Research Laboratories, Uganda CIP International Center for Potato OFSP Orange fleshed-sweet CIRAD Agricultural Research Institute for Developing Countries, France potato POD: Peroxidase DCP Dichlorophenol R gas constant = 8.314 J · K −1 · mol −1 DHA Dihydroactinidiolide RDA Recommended Dietary Allowance Ea Activation energy (kJ.mol -1 ) RE Retinol Equivalent EDTA Ethylene diamine tetra acetic acid SO2 Sulphur gas FAO Food Agriculture Organization SPME/GC/MS Solid-phase microextraction/Gas Chromatography/Mass Spectra HIV Human Immunodeficiency Virus TDRI Thailand Development Research Institute HPDE High density polythene Tukey HSD Tukey’s honest significant difference HPLC High Liquid Performance Chromatography ITDG Intermediate Technology Development Group VAD Vitamin A deficiency VITAA Vitamin A Partnership for Africa k degradation constant rate (day -1 ) WFSP White fleshed-sweet potato WHO World Health Organization
CONTENTS CHAPTER 1.! LITERATURE REVIEW ............................................................................................. 1! 1.1! BACKGROUND.......................................................................................................................... 1! 1.1.1! Introduction ......................................................................................................................... 1! 1.1.2! Vitamin A deficiency ............................................................................................................ 2! 1.1.3! Importance of sweet potato ................................................................................................. 5! 1.1.4! Uses of dried sweet potatoes ............................................................................................... 9! 1.2! DRYING AND STORAGE TECHNOLOGIES ADAPTED TO LOCAL CONDITIONS ........ 14! 1.2.1! Introduction ....................................................................................................................... 14! 1.2.2! Artificial drying ................................................................................................................. 15! 1.2.3! Sun drying.......................................................................................................................... 16! 1.2.4! Shade drying ...................................................................................................................... 17! 1.2.5! Solar drying ....................................................................................................................... 17! 1.2.6! Packaging .......................................................................................................................... 21! 1.2.7! Pre-treatments to limit provitamin A degradation ............................................................ 22! 1.2.8! Storage at low temperatures .............................................................................................. 23! 1.3! DEGRADATION OF CAROTENOIDS .................................................................................... 23! 1.3.1! Introduction to carotenoids ............................................................................................... 23! 1.3.2! Incorporation of carotenoids in the plant structure and human absorption ..................... 25! 1.3.3! Factors affecting degradation of β-carotene ..................................................................... 27! 1.3.4! Mechanisms of degradation .............................................................................................. 30! 1.3.5! Products of degradation .................................................................................................... 35! 1.4! INFLUENCE OF DRYING AND STORAGE ON CAROTENOID LOSS IN SWEET POTATO ROOTS ................................................................................................................................................... 37! 1.4.1! Introduction ....................................................................................................................... 37! 1.4.2! Determination of carotenoid degradation ......................................................................... 37! 1.4.3! Carotenoid losses after drying .......................................................................................... 40! 1.4.4! Carotenoid losses during storage of dried products ......................................................... 45! 1.4.5! Carotenoid losses during food preparation ....................................................................... 49! 1.5! SUMMARY OF ISSUES HIGHLIGHTED BY THE LITERATURE REVIEW AND OBJECTIVES OF THE RESEARCH ..................................................................................................... 50! 1.5.1! Summary and outcomes ..................................................................................................... 50! 1.5.2! Hypothesis and objectives of the research ......................................................................... 51! CHAPTER 2.! DESCRIPTION AND ASSESSMENT OF METHODS .......................................... 52! 2.1! INTRODUCTION...................................................................................................................... 52! 2.2! GENERAL DESCRIPTION OF ROOT MATERIAL, DRYING AND STORAGE PROCESSES…………… ....................................................................................................................... 52! 2.2.1! Flow chart of sweet potato drying and storing .................................................................. 52! 2.2.2! Root samples...................................................................................................................... 53! 2.2.3! Drying of sweet potato chips ............................................................................................. 55! 2.2.4! Dry matter determination .................................................................................................. 55! 2.2.5! Water activity .................................................................................................................... 55! 2.2.6! Storage of dried sweet potato samples .............................................................................. 56! 2.2.7! Transport of samples ......................................................................................................... 56! 2.3! DESCRIPTION OF CAROTENOID ANALYIS ...................................................................... 56! 2.3.1! Preparation of homogeneous samples for carotenoid analysis ......................................... 56! 2.3.2! Colorimetric analysis ........................................................................................................ 57! 2.3.3! Carotenoid analysis by Dhuique-Mayer’s method (France) ............................................. 57! 2.3.4! Carotenoid analysis by HarvestPlus method (UK and Uganda) ....................................... 60! 2.3.5! SPME/GC/MS analysis ...................................................................................................... 62! 2.3.6! Statistical analyses ............................................................................................................ 63 VII
Page 1 and 2: Investigating carotenoid loss after
Page 3 and 4: DECLARATION I certify that this wor
Page 5: ACKNOWLEDGEMENTS I am deeply gratef
Page 9 and 10: 4.3.2! Effect of trial and sweet po
Page 11 and 12: 1.1 BACKGROUND 1.1.1 Introduction C
Page 13 and 14: 3 1. Literature review It is estima
Page 15 and 16: 5 1. Literature review food corresp
Page 17 and 18: - the leaves that make energy and s
Page 19 and 20: 9 1. Literature review Uganda and M
Page 21 and 22: 11 1. Literature review communicati
Page 23 and 24: 13 1. Literature review soya grains
Page 25 and 26: 15 1. Literature review Drying is a
Page 27 and 28: 17 1. Literature review Modelling o
Page 29 and 30: 19 1. Literature review Other types
Page 31 and 32: 21 1. Literature review The perform
Page 33 and 34: 23 1. Literature review degradation
Page 35 and 36: 25 1. Literature review carotene an
Page 37 and 38: 27 1. Literature review (Rees, NRI,
Page 39 and 40: 29 1. Literature review red (>800 n
Page 41 and 42: 31 1. Literature review Figure 1-17
Page 43 and 44: 33 1. Literature review induced by
Page 45 and 46: 35 1. Literature review Enzymatic c
Page 47 and 48: 37 1. Literature review Volatile pr
Page 49 and 50: 39 1. Literature review Carotenoid
Page 51 and 52: Table 1-5: Effect of type of proces
Page 53 and 54: Comparison of losses in drying proc
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47 1. Literature review Different p
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Oxygen 49 1. Literature review Oxyg
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51 1. Literature review the storage
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2.2.2 Root samples 53 2. Assessment
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2.2.5 Water activity 55 2. Assessme
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57 2. Assessment of Methods below t
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59 2. Assessment of Methods !-carot
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61 2. Assessment of Methods indicat
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63 2. Assessment of Methods were we
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65 2. Assessment of Methods Table 2
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67 2. Assessment of Methods Intra-l
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69 2. Assessment of Methods Signifi
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71 2. Assessment of Methods Table 2
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Content (µg/g) Content (µg/g) Con
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75 2. Assessment of Methods way-ANO
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77 2. Assessment of Methods puree.
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Percentage loss "a" redness 45% 40%
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CHAPTER 3. 81 3. Preliminary study
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83 3. Preliminary study Figure 3-1:
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85 3. Preliminary study Air velocit
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3.2.10 Statistical analyses 87 3. P
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89 3. Preliminary study because it
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Sample area (cm2) 91 3. Preliminary
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Figure 3-9: UV-Visible spectrum of
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95 3. Preliminary study Mulokozi an
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97 3. Preliminary study One hundred
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99 4. Ugandan field study respectiv
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Transmittance (%) 101 4. Ugandan fi
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4.2.5 Total carotenoids extraction
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105 4. Ugandan field study The dryi
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107 4. Ugandan field study individu
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109 4. Ugandan field study values a
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111 4. Ugandan field study caroteno
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113 4. Ugandan field study observed
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115 4. Ugandan field study OFSP chi
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117 5. Mozambican field study carot
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119 5. Mozambican field study kg (p
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121 5. Mozambican field study Table
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Tot. carotenoid content (!g/g) Tot.
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127 5. Mozambican field study 5.3.6
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a b c c 129 5. Mozambican field stu
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131 5. Mozambican field study Table
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133 5. Mozambican field study #-car
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CHAPTER 6. 137 6. Effect of pre-tre
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139 6. Effect of pre-treatment out
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141 6. Effect of pre-treatment afte
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143 6. Effect of pre-treatment leve
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145 6. Effect of pre-treatment Citr
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147 6. Effect of pre-treatment trea
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149 6. Effect of pre-treatment inte
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CHAPTER 7. 151 7. Involvement of en
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7.2.2. pH measurement 153 7. Involv
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155 7. Involvement of enzymes glyce
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157 7. Involvement of enzymes Table
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159 7. Involvement of enzymes carot
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161 7. Involvement of enzymes carot
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163 7. Involvement of enzymes Perox
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CHAPTER 8. 165 8. Study under contr
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Kilner jar (with metal lever catch
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Figure 8-2: Storage system for wate
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8.2.4 Carotenoid analyses 171 8. St
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8.3 RESULTS & DISCUSSION 8.3.1 Samp
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175 8. Study under controlled condi
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k (day-1) k (day-1) 0.10 0.08 0.06
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CHAPTER 9. GENERAL DISCUSSION AND F
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197 9. Discussion carotene loss aft
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199 9. Discussion total carotenoids
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9.4.2 Varietal influence 201 9. Dis
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203 9. Discussion 2008). The side e
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205 9. Discussion Absence of cis-is
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207 9. Discussion (Chapter 7). Howe
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209 9. Discussion of these cultivar
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References 211 References Aguayo, V
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213 References Bechoff, A., Dhuique
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215 References Chen, H.E., Peng, H.
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DIAS (2006) Semi-Annual and Annual
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219 References Tropical Agriculture
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221 References has a positive effec
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223 References Kamiya N. and Nagamu
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Lee, S.B. and Kim, K.J. (1995) Effe
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227 References Mills, R.C. and Hart
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Nestel, P., Bouis, H.E., Meenakshi,
Page 241 and 242:
231 References Preston, C.M. and Ba
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Simon, P.W. (1997) Plant pigments f
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235 References Tran, T.H., Nguyen,
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237 References Walter, W.M., Purcel
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! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! A
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Arrhenius model: = ∞ − Ea RT ek
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242 Appendix 1 B/Calculation of Arr
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Temperature is integrated for each
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2) Integration of temperature in Ug
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Appendix 2b: Dryers cost in Lualua,
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250 Appendix 2 Technical informatio
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252 Appendix 2 Technical informatio
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Open air flat and sloped dryers 254
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Appendix 3: Total carotenoids metho
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4. Partition - Pour 40 ml of Petrol
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