Investigating carotenoid loss after drying and storage of

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Storage time (days) Storage time (days) Storage time (days) 220 200 180 160 140 120 100 80 60 40 20 220 200 180 160 140 120 100 80 60 40 20 220 200 180 160 140 120 100 80 60 40 20 0 Loss 10% 20% 30% 40% 50% (Α) (Α) ββ-carotene β 10% 20% 30% 40% 50% (C) Total carotenoids 180 8. Study under controlled conditions 0 10 15 20 25 30 35 40 10% T (°C) Loss 20% 30% 40% 50% (B) 5,6 epoxy-β− β− β−carotene β− 0 10 15 20 25 30 35 40 T (°C) Loss 10 15 20 25 30 35 40 T (°C) Figure 8-7: Prediction curves of carotenoid (β-carotene (A); 5,6-epoxy-β-carotene (B); total-carotenoids (C)) loss (%) on a fresh weight basis with temperature and with storage time in dried sweet potato chips stored between 10-40 ºC in air; aw 0.52-0.65.
181 8. Study under controlled conditions These curves can be used for practical applications, such as the determination of product shelf life. For instance, for a 20% loss in β-carotene (Figure 8-7A), the predicted storage duration in tropical conditions (average 30 ºC) is about 10 days. On the other hand, if the dried sweet potato is stored at temperate ambient temperature (average 20 ºC), then the predicted storage time is one month. If it is stored in refrigerated conditions (average 10 ºC) the predicted storage time increases up to 70 days. Predicted storage time based on total carotenoids (Figure 8-7B) is slightly shorter and when based on 5,6 epoxy-β- carotene, longer (Figure 8-7C) because the barrier energy to overcome (Ea) is lower for total carotenoids and higher for 5,6 epoxy-β-carotene. For instance, for a sample stored at 10 ºC, the storage duration would be 160, 200 and 110 days for a 40% loss in β- carotene, 5,6-epoxy-β-carotene or total carotenoids respectively. 8.3.4 Influence of water activity and oxygen on carotenoid degradation Water activity The water sorption properties of dried sweet potato chips stored at 40ºC in different saturation salt solutions are shown in Figures 8-8 and 8-9. aw/(M(1-aw)) 10 9 8 7 6 5 4 3 2 1 0 y = 17.99x - 0.257 R 2 = 0.999 0.0 0.1 0.2 0.3 0.4 0.5 0.6 aw Figure 8-8: Linearised equation of Brunauer-Emmett-Teller (BET) for dried sweet potato chips at 40ºC and stored for 54 days. C and M0 were calculated from the linearised equation. BET model (C = -68.88, M0 = 0.0564). The experimental data were fitted with the BET equation (R 2 = 0.999) for an aw interval of 0.13-0.76. At high water activity for a dried flour (aw = 0.76), the BET model slightly
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Investigating carotenoid loss after
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DECLARATION I certify that this wor
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ACKNOWLEDGEMENTS I am deeply gratef
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CONTENTS CHAPTER 1.! LITERATURE REV
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4.3.2! Effect of trial and sweet po
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1.1 BACKGROUND 1.1.1 Introduction C
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3 1. Literature review It is estima
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5 1. Literature review food corresp
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- the leaves that make energy and s
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9 1. Literature review Uganda and M
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11 1. Literature review communicati
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13 1. Literature review soya grains
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15 1. Literature review Drying is a
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17 1. Literature review Modelling o
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19 1. Literature review Other types
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21 1. Literature review The perform
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23 1. Literature review degradation
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25 1. Literature review carotene an
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27 1. Literature review (Rees, NRI,
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29 1. Literature review red (>800 n
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31 1. Literature review Figure 1-17
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33 1. Literature review induced by
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35 1. Literature review Enzymatic c
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37 1. Literature review Volatile pr
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39 1. Literature review Carotenoid
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Table 1-5: Effect of type of proces
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Comparison of losses in drying proc
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45 1. Literature review observed we
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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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123 5. Mozambican field study carot
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Tot. carotenoid content (!g/g) Tot.
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127 5. Mozambican field study 5.3.6
Page 139 and 140: a b c c 129 5. Mozambican field stu
Page 141 and 142: 131 5. Mozambican field study Table
Page 143 and 144: 133 5. Mozambican field study #-car
Page 145 and 146: 135 5. Mozambican field study carot
Page 147 and 148: CHAPTER 6. 137 6. Effect of pre-tre
Page 149 and 150: 139 6. Effect of pre-treatment out
Page 151 and 152: 141 6. Effect of pre-treatment afte
Page 153 and 154: 143 6. Effect of pre-treatment leve
Page 155 and 156: 145 6. Effect of pre-treatment Citr
Page 157 and 158: 147 6. Effect of pre-treatment trea
Page 159 and 160: 149 6. Effect of pre-treatment inte
Page 161 and 162: CHAPTER 7. 151 7. Involvement of en
Page 163 and 164: 7.2.2. pH measurement 153 7. Involv
Page 165 and 166: 155 7. Involvement of enzymes glyce
Page 167 and 168: 157 7. Involvement of enzymes Table
Page 169 and 170: 159 7. Involvement of enzymes carot
Page 171 and 172: 161 7. Involvement of enzymes carot
Page 173 and 174: 163 7. Involvement of enzymes Perox
Page 175 and 176: CHAPTER 8. 165 8. Study under contr
Page 177 and 178: Kilner jar (with metal lever catch
Page 179 and 180: Figure 8-2: Storage system for wate
Page 181 and 182: 8.2.4 Carotenoid analyses 171 8. St
Page 183 and 184: 8.3 RESULTS & DISCUSSION 8.3.1 Samp
Page 185 and 186: 175 8. Study under controlled condi
Page 189: 179 8. Study under controlled condi
Page 193 and 194: k (day-1) k (day-1) 0.10 0.08 0.06
Page 205 and 206: CHAPTER 9. GENERAL DISCUSSION AND F
Page 207 and 208: 197 9. Discussion carotene loss aft
Page 209 and 210: 199 9. Discussion total carotenoids
Page 211 and 212: 9.4.2 Varietal influence 201 9. Dis
Page 213 and 214: 203 9. Discussion 2008). The side e
Page 215 and 216: 205 9. Discussion Absence of cis-is
Page 217 and 218: 207 9. Discussion (Chapter 7). Howe
Page 219 and 220: 209 9. Discussion of these cultivar
Page 221 and 222: References 211 References Aguayo, V
Page 223 and 224: 213 References Bechoff, A., Dhuique
Page 225 and 226: 215 References Chen, H.E., Peng, H.
Page 227 and 228: DIAS (2006) Semi-Annual and Annual
Page 229 and 230: 219 References Tropical Agriculture
Page 231 and 232: 221 References has a positive effec
Page 233 and 234: 223 References Kamiya N. and Nagamu
Page 235 and 236: Lee, S.B. and Kim, K.J. (1995) Effe
Page 237 and 238: 227 References Mills, R.C. and Hart
Page 239 and 240: Nestel, P., Bouis, H.E., Meenakshi,
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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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