臺灣博碩士論文加值系統

全世界甘藷塊根的年產量超過133億噸，分別為開發中國家第五及世界第七大宗的主要糧食作物。本研究評估並比較三種不同品系的甘藷（Ipomoea batatas Lam.）:台農57、台農66及台農73之抗氧化活性、酚類及類胡蘿蔔素含量與顏色參數，研究主要探討因子有萃取溶劑、不同甘藷品系、不同甘藷部位、乾燥方式、分離方法、貯存溫度及貯存時間的影響。
結果顯示萃取的溶劑中:以乙醇和乙醚萃取所得的平均總酚含量較高，之後依序為丙酮、甲醇、乙酸乙酯、50%乙醇及去離子水；以DPPH法評估抗氧化活性，結果顯示以甲醇、乙醇及丙酮的萃取物平均抗氧化活性較高，依序為乙醚、乙醇水溶液、乙酸乙酯及去離子水。由於以乙醇萃取具有較高的抗氧化效果且相對於丙酮、乙酸乙酯及甲醇，其毒性較低，因此選為進一步之萃取溶劑。在不同品系間，其多酚含量及抗氧化活性含量依序為台農73＞台農66＞台農57；台農66品系則表現出較高含量之類胡蘿蔔素，而台農57 及台農73中的總胡蘿蔔素含量極低，甘藷皮之抗氧化活性及酚含量均高於果肉的部位。
以冷凍乾燥處理的樣品其抗氧化活性及酚類含量平均高於以空氣乾燥處理的樣品。空氣乾燥法包含有日曬、低溫乾燥（25C）及熱風乾燥 ﹙50ºC及75ºC﹚共5種，結果顯示以DPPH、linoleic acid抗氧化系統﹙AOP﹚和ABTS測定後三種不同品系之甘藷其抗氧化活性均明顯下降。抗氧化活性的下降歸因於總酚及總類黃酮含量的下降。而其中台農73之抗氧化活性，在熱風乾燥過程，抗氧化活性、總酚及總類黃酮含量會隨溫度增加而下降。然而台農57 及台農66的抗氧化活性、總酚及總類黃酮含量會隨著乾燥溫度增加及時間減少而增加。由結果顯示食品在乾燥過程中，抗氧化物質及其活性的變化和品系具有相關性，低溫乾燥法不但費時且製程難以放大，而台農73品系，較適合以乾燥處理。
由於此三種抗氧化分析方法之間缺乏相關性，因此利用決定係數（R2）及變異係數（CV）來探討它們之間的最適配合度；結果顯示，這些方法之間因缺乏足夠的證據來指出哪個方法較佔優勢，因此利用單一抗氧化活性指標（single AOA indicator），也稱作抗氧化相關的期望指標（relative desirability index），來評估DPPH、AOP及ABTS之能力，以克服不同方法間缺乏相關性的問題。台農57品系，經冷凍乾燥後其RDI值最高，日曬乾燥最低，相較於多酚及胡蘿蔔素含量，以胡蘿蔔素含量與RDI值有較高的相關性；而台農66品系，經冷凍乾燥後其RDI值最高，日曬乾燥最低。在低溫與熱風乾燥（50 ºC 及75 ºC）時，台農57 及台農66品系，其RDI值會伴隨乾燥溫度增加而降低；台農73品系，以冷凍乾燥法處理其RDI值最高，其次為75C熱風乾燥、日曬乾燥及50C熱風乾燥，以25 ºC處理的樣品其RDI值最低。於台農66及台農73品系，其多酚含量較胡蘿蔔素含量呈現較高的RDI相關性。不同品系之最適乾燥條件，分別為台農73品系: 75 ºC，24 小時、台農57品系及台農66品系，為 25ºC， 10天。
於台農73品系中含有三種主要的酚類化合物；亦即，兒茶素 （catechin）、芸香素（rutin）及沒食子酸（gallic acid），其在萃取物中的含量依序為268.24 mg/kg、67.06 mg/kg 及 25.56 mg/kg。在甘藷不同部位方面，皮的部份以catechin 及 gallic acid含量較高，rutin含量少於果肉的部份，在台農73中主要的抗氧化活性來源為rutin，依序為catechin及 gallic acid。
在貯存試驗方面，樣品貯存在4℃及室溫下其總酚含量並沒有顯著差異，但抗氧化活性以貯存在4℃較室溫為佳；然而，總酚含量和抗氧化活性，均會隨貯存時間增加而下降；甘藷果肉經貯存在室溫9個月及4 ℃貯存10個月其總酚含量會顯著下降，而甘藷皮經貯存在4℃及室溫，11個月總酚含量；甘藷果肉貯存在室溫，5個月及4 ℃，10個月其抗氧化活性均會顯著下降，而甘藷皮經貯存於4℃，11個月其抗氧化活性會顯著下降。
糊化分析方面，結果顯示三種不同品種的尖峰黏度及最終黏度，分別超過495及335 RVU，且尖峰黏度在80 ℃，5分鐘內，由以上結果顯示，三種不同品種的甘藷其萃取殘留物可以應用在原料需要適度高糊化的凝膠食品或其它食品，由本研究的結果中證明將地瓜萃取後的殘留物製成布丁、餅乾及蛋糕是可行的。

Sweet potato production and utilization exceeds 133 million tons of tuberous roots annually in the world. It represents the 5th and 7th staple food crop in developing countries and the world, respectively. This study evaluated and compared three sweet potato (Ipomoea batatas Lam.) cultivars: Tainong 57 (TNG57), Tainong 66 (TNG66), and Tainong 73 (TNG73) on the basis of their antioxidant activity (AOA), phenolic and carotenoid contents, and color parameters. The effects of extracting solvent, genotype, part of the root, drying method, fractionation method, storage temperature, and storage duration were tested.
The results showed that on average, ethanol and diethyl ether (DE) extracts exhibited the highest total phenolic contents, followed in descending order by acetone, methanol, ethyl acetate (EA), aqueous ethanol (1:1 v/v) and distilled de-ionized water (ddH2O) extracts. The highest AOA, as evaluated by 1, 1-diphenyl-2-picrylhydrazyl (DPPH) assay, were observed in methanol, ethanol, and acetone extracts, followed in descending order by DE, aqueous ethanol, and EA, and ddH2O extracts. Due to its high effectiveness and its relative lower toxicity compared to acetone, DE and methanol, ethanol was chosen for further extractions. Among the three cultivars, TNG73 had on average the highest phenolic content and AOA, followed by TNG66 and TNG57. TNG66 exhibited the highest carotenoid content, while TNG57 and TNG73 showed low content of total carotenoids. The skin samples had, on average, a higher AOA and phenolic content than the flesh samples.
Freeze-dried samples had on average higher AOA and phenolic content than the air-dried samples. During the air-drying process, including sun-drying, low temperature air drying (LTD) at 25C, hot air drying (HAD) at 50ºC, and HAD at 75ºC, we observed in the three cultivars significant decreases of the AOA, as evaluated by DPPH, anti-oxidative potency in linoleic acid system model (AOP); and 2,2’-Azino-di-[3-ethylbenzothiazoline-6-sulfonate] (ABTS) assays. The decrease of AOA was attributed to a decrease of total phenolics and total flavonoids. The losses of AOA, total phenolics, and total flavonoids decreased with the increase of the drying temperature and the decrease of the drying time of TNG73 during the air-drying process. However, in TNG57 and TNG66, an increase of the losses of AOA, total phenolics, and total flavonoids during the air-drying process was observed with the increase of the drying temperature associated with a decrease of the drying time. These results indicated that changes in antioxidant components and activities during food drying are genotype-dependant, as the trend of variation was different for the three cultivars. As LTD is time consuming and difficult to scale up, TNG73 was therefore the most suitable for being processed by drying.
Low correlations were observed among the three AOA analytical methods. Therefore, their relative goodness of fit was studied using the coefficients of determination (R2) and variation (CV). Based on the results, there was no sufficient evidence to show that one method was better than another. Thus, a single AOA indicator, referred to as AOA relative desirability index (RDI), was computed from the results of DPPH, AOP, and ABTS assays to overcome the problem of lack of correlation among the analytical methods used. For TNG57, the highest RDI value was observed in freeze-dried samples, while the lowest was observed in those treated by sun-drying. Higher correlation of the RDI was observed with carotenoid than with phenolic contents of TNG57. For TNG66, freeze-dried samples showed the highest RDI, followed by sun-dried ones. In LTD, HAD at 50ºC, and HAD at 75ºC, the RDI decreased with the increase of the drying temperature for both TNG57 and TNG66. For TNG73, the highest RDI was observed in freeze-drying, followed by HAD at 75C, then sun-drying, and then HAD at 50C. The samples dried at 25ºC showed the lowest RDI. Both for TNG66 and TNG73, higher correlation of the RDI was observed with phenolic than carotenoid contents. The best air-drying conditions were at 75ºC for 24 h for TNG73, and at 25C for 10 days for TNG57 and TNG66.
Three major phenolic compounds, namely, catechin, rutin, and gallic acid were identified in TNG73. Catechin (268.24 mg/kg dry matter) was the highest, followed by rutin (67.06 mg/kg dry matter), and then gallic acid (25.56 mg/kg dry matter), respectively. Comparing with the flesh samples, the skin exhibited higher contents of catechin and gallic acid, but had lower content of rutin. Rutin was the major contributor to the AOA of TNG73, followed by catechin, and gallic acid.
In a storage test, the samples stored at room temperature and 4ºC did not show significant difference in the total phenolic content, but the AOA was on average lower at room temperature than at 4ºC. Both the AOA and total phenolics exhibited a general trend of decrease during the storage. The decrease of the total phenolics of the flesh samples was significant after nine-month storage at room temperature and 10 months at 4ºC. For the skin samples, the decrease of total phenolics was significant after 11-month storage both at room temperature and 4ºC. The decrease of the AOA of the flesh samples was significant after five-month storage at room temperature and 10-moonth storage at 4ºC. For the skin samples, the decrease of AOA was significant after 11-month storage both at room temperature and at 4ºC.
Results of a pasting profile analysis showed that the peak and final viscosity of the starches isolated from all three cultivars exceeded 495 and 335 RVU, respectively, with a peak viscosity time shorter than 5 min around 80ºC. These results showed that the solid extraction residue of the three cultivars could be processed as gel foods and other food items that require moderate to high gelatinization ability of the raw material. Sweet potato-based puddings, cookies, and cakes prepared in this study supported our findings of the suitability and usefulness of the starches contained in the residue of sweet potato after extraction of antioxidants.

Table of Contents

List of Figures XVIII
List of Tables XXI
PART I. GENERAL FRAMEWORK 1
Chapter 1. General introduction 1
1.1. Background information and justifications 1
1.2. Objectives 6
1.2.1. Overall objective 6
1.2.2. Specific objectives 6
1.3. Hypothesis 8
1.4. Research questions 9
PART II. LITERATURE REVIEW 10
Chapter 2. An overview of sweet potato, food constituents, and food analysis 10
Abstract 10
2.1. An overview of sweet potato 11
2.1.1. General description 11
2.1.2. Origin, distribution, and production 11
2.1.3. Use and nutritional value 12
2.1.4. Sweet potato cultivars 13
2.1.5. Sweet potato and food and nutrition security 14
2.2. Food constituents and analysis 18
2.2.1. Introduction 18
2.2.2. Macronutrients 18
2.2.2.1. Carbohydrates in foods 18
2.2.2.2. Proteins in foods 19
2.2.2.3. Lipids in foods 19
2.2.2.4. Water in food 20
2.2.3. Micronutrients 21
2.2.3.1. Natural emulsifiers 21
2.2.3.2. Organic acids 21
2.2.3.3. Oxidants and antioxidants 21
2.2.3.4. Enzymes 22
2.2.3.5. Pigments and colors 22
2.2.3.6. Flavors 23
2.2.3.7. Vitamins and minerals 24
2.2.3.8. Natural toxicants 24
2.2.4. Proximate analysis of foods 25
2.2.5. Concepts of functional foods and secondary metabolites in foods 26
2.2.6. Antioxidants in foods: concept, role, and assessment 27
2.2.6.1. Concepts and importance 27
2.2.6.2. Antioxidants and health promotion 28
2.2.6.3. Concept of total antioxidant activity of foods 29
2.2.6.4. Strategies to measure total antioxidant activity of foods 30
2.2.6.5. Some selected techniques of assessment total AOA in foods 31
2.2.6.5.1. DPPH method 31
2.2.6.5.2. ABTS methods 32
2.2.6.5.3. TEAC method 33
2.2.6.5.4. ORAC method 33
2.2.7. Place of the solvent in antioxidant activity analyses 34
2.2.8. Phenolic compounds in foods 34
2.2.8.1. Total phenolic content assessment 35
2.2.8.2. Total flavonoids content assessment 36
2.2.9. Carotenoids in foods 36
2.2.9.1. Occurrence and role 36
2.2.9.2. Carotenoids analysis 39
2.3. Conclusions 42
PART III. EXPERIMENTATION 43
Chapter 3. Color characteristics, proximate composition, and carotenoid content of TNG57, TNG66, and TNG73 sweet potato (Ipomoea batatas Lam.) cultivars 46
Abstract 46
3.1. Introduction 47
3.2. Materials and Methods 49
3.2.1. Materials 49
3.2.2. Experiment design 49
3.2.3. Color parameter measurements 49
3.2.4. Proximate analysis 51
3.2.5. Carotenoids extraction 52
3.2.6. Total carotenoids and beta-carotene analysis 53
3.2.7. Statistical analysis 54
3.3. Results 55
3.3.1. Color parameters 55
3.3.2. Proximate composition 55
3.3.3. Total carotenoids and beta-carotene contents 59
3.4. Discussion 62
3.5. Conclusions 63
Chapter 4. Total phenolics and antioxidant activity of sweet potato (Ipomoea batatas Lam.) as affected by the extracting solvent and the genotype 64
Abstract 64
4.1. Introduction 65
4.2. Materials and Methods 68
4.2.1. Materials 68
4.2.2. Experiment design 68
4.2.3. Crude extract preparation 70
4.2.4. Total phenolic content assay 70
4.2.4. Antioxidant activity assay 72
4.2.6. Statistical analysis 73
4.3. Results 75
4.3.1. Total phenolic content 75
4.3.2. DPPH free radical scavenging activity (FRSA) 78
4.3.3. Correlations between antioxidant activity (AOA) and total phenolic content 81
4.3.4. Heat stability of ethanol extracts of sweet potato antioxidant activity in liquid media incubated at increasing temperature 84
4.4. Discussion 86
4.5. Conclusions 90
Chapter 5. Effect of freeze-drying on phenolic content and antioxidant activity of TNG57, TNG66, and TNG73 cultivars of sweet potato (Ipomoea batatas Lam.) 91
Abstract 91
5.1. Introduction 92
5.2. Materials and Methods 95
5.2.1. Materials 95
5.2.2. Experiment design 95
5.2.3. Sample preparation and extraction 95
5.2.4. Total phenolic and total flavonoids assays 96
5.2.5. Antioxidant activity (AOA) assays 96
5.2.6. Statistical analysis 97
5.3. Results 99
5.3.1. Dry matter content and extraction yield of the samples 99
5.3.2. Total phenolic and total flavonoid contents 99
5.3.2. DPPH free radical scavenging activity 103
5.3.2. ABTS free radical scavenging activity 106
5.4. Discussion 111
5.5. Conclusions 112
Chapter 6. Effects of different air drying methods on color parameters, antioxidant activity, phenolic, and carotenoid content of TNG57, TNG66, and TNG73 sweet potato (Ipomoea batatas Lam.) cultivars 113
Abstract 113
6.1. Introduction 114
6.2. Materials and Methods 115
6.2.1. Materials 115
6.2.2. Experiment design 115
6.2.3. Sample preparation and color parameter measurements 115
6.2.4. Crude extract preparation 116
6.2.5. Carotenoids extraction 116
6.2.6. Total phenolic, total flavonoid, total carotenoid, and beta-carotene contents assays 118
6.2.7. Determination of the antioxidant activity 118
6.2.8. Determination of a single antioxidant activity indicator 120
6.2.9. Statistical analysis 120
6.3. Results 122
6.3.1. Effect of the drying process on the color parameters 122
6.3.2. Effect of the drying process on total phenolic and flavonoid contents 130
6.3.3. Effect of the drying process on the total carotenoid and beta-carotene contents 135
6.3.4. Effect of the drying process on the antioxidant activity 142
6.3.5. Correlations among the antioxidant activity indicators, total phenolic, flavonoid, carotenoid, and β-carotene contents 152
6.3.6. Relative fit goodness of the three analytical methods 155
6.3.7. Effect of the drying process on the RDI Value 161
6.4. Discussion 165
6.5. Conclusions 166
Chapter 7. Extraction, HPLC separation, and characterization of the major phenolic antioxidants of TNG73 sweet potato (Ipomoea batatas Lam.) cultivar 167
Abstract 167
7.1. Introduction 168
7.2. Materials and Methods 170
7.2.1. Materials 170
7.2.2. Sample preparation 170
7.2.3. Extraction 170
7.2.4. Fractionation 171
7.2.5. Experiment Design 174
7.2.6. HPLC separation and phenolic profile analysis 174
7.2.7. Antioxidant activity (AOA) assay 175
7.2.8. Statistical analyses 175
7.3. Results 177
7.3.1. Phenolic profile of TNG73 177
7.3.2. Distribution of rutin, gallic acid, and catechin in the skin and the flesh of TNG73 177
7.3.3. Comparison of LLP and PHM methods to extract catechin, rutin, and gallic acid of TNG73 182
7.3.4. Distribution of rutin, catechin, and gallic acid in different fractions of TNG73 182
7.3.5. DPPH FRSA of different fractions of TNG73 185
7.3.6. Contribution of individual phenolic compounds to the AOA of TNG73 188
7.4. Discussion 193
7.5. Conclusions 195
Chapter 8. Evolution of the total phenolic content and antioxidant activity of TNG73 sweet potato (Ipomoea batatas Lam.) flour during 12-month storage 196
Abstract 196
8.1. Introduction 197
8.2. Material and Methods 199
8.2.1. Materials 199
8.2.2. Experiment design 199
8.2.3. Sample preparation 199
8.2.5. Total phenolic content measurements 200
8.2.6. Antioxidant activity (AOA) assay 200
8.2.7. Statistical analyses 201
8.3. Results 202
8.3.1. Total phenolic content 202
8.3.2. Antioxidant activity 207
8.4. Discussion 215
8.5. Conclusions 217
Chapter 9. Pasting behavior of TNG57, TNG66, and TNG73 sweet potato starch and flour and their applicability in new food product development 218
Abstract 218
9.1. Introduction 219
9.2. Materials and methods 221
9.2.1. Materials 221
9.2.2. Flour preparation and starch extraction 221
9.2.3. Pasting behavior evaluation 221
9.2.4. Development of new food products 223
9.2.5. Sensory evaluation of the new products 227
9.3. Results 230
9.3.1. Pasting behavior of starches extracted from TNG57, TNG66, and TNG73 230
9.3.2. Pasting behavior of flour of TNG57, TNG66, and TNG73 233
9.3.3. Results of the sensory evaluation of the new products 236
9.4. Discussion 245
9.5. Conclusions 246
Chapter 10. General summary conclusions 247
References 250
Index 278
Appendix 281
Biosketch (Vitae) of the author 303


List of Figures
Figure 1. Diagram of the study design. 45
Figure 2. Illustration of the experiment design for proximate analysis conducted in step one of the research project. 50
Figure 3. Color appearance of entire and cut roots of TNG57, TNG66, and TNG73. 57
Figure 4. Representative chromatograms of beta-carotene and TNG66 extract. 60
Figure 5. Flowchart of the sample extraction to measure DPPH FRSA and total phenolic content of fresh samples. 71
Figure 6. Dose-response curve of DPPH FRSA of vitamin C. 79
Figure 7. Decrease of the total phenolics and total flavonoids of TNG73 during freeze-drying. 102
Figure 8. DPPH FRSA of of raw and freeze-dried sweet potato cv TNG57 TNG66, and TNG73. 104
Figure 9. ABTS FRSA of raw and freeze-dried sweet potato cv TNG57, TNG66, and TNG73. 107
Figure 10. Flowchart of samples preparation to assess the effects of the drying process on the antioxidant activity, phenolic, and carotenoid contents. 117
Figure 11. Visual color appearances of TNG57 before and after drying. 124
Figure 12. Visual color appearances of TNG66 before and after drying. 126
Figure 13. Visual color appearance of the TNG73 after drying at in different conditions. 129
Figure 14. Decrease of the total phenolic and total flavonoid contents of TNG57 during air-drying with regards to the freeze-drying values. 132
Figure 15. Decrease of the total phenolic and total flavonoid contents of TNG66 during air-drying with regards to the freeze-drying values. 134
Figure 16. Representative chromatograms of a standard beta-carotene solution and fractions of TNG66. 139
Figure 17. Decrease of the DPPH FRSA, AOP, and ABTS FRSA of TNG57 during air-drying with regards to the freeze-drying values. 144
Figure 18. Decrease of the DPPH FRSA, AOP, and ABTS FRSA of TNG66 during air-drying with regards to the freeze-drying values. 147
Figure 19. Decrease of the DPPH FRSA, AOP, and ABTS FRSA of TNG73 during air-drying with regards to the freeze-drying values. 151
Figure 20. Antioxidant activity relative desirability index (RDI) of the flesh of TNG57 submitted to different drying processes. 162
Figure 21. Antioxidant activity relative desirability index (RDI) of the flesh of TNG66 submitted to different drying processes. 163
Figure 22. Antioxidant activity relative desirability index (RDI) of TNG73 submitted to different drying processes. 164
Figure 23. Flowchart of fractionation of TNG7373 ethanol extract by liquid-liquid partition using immiscible solvents 172
Figure 24. Flowchart of fractionation of TNG73 ethanol extract by pH modification 173
Figure 25. Representative chromatograms of a standard phenolics solution and fractions of TNG73. 179
Figure 26. Comparative contents of catechin, rutin, and gallic acid in the skin and the flesh of TNG73. 181
Figure 27. Comparative contents of catechin, rutin, and gallic acid, obtained by liquid-liquid partition (LLP) and pH modification (PHM) methods in TNG73. 183
Figure 28. Contents of catechin, rutin, and gallic acid of different fractions of TNG73. 184
Figure 29. DPPH FRSA vs concentration of different fractions of the skin and the flesh of TNG73. 186
Figure 30. DPPH IC50 of different fractions of the skin and the flesh of TNG73. 187
Figure 31. General evolution trend of total phenolics content of TNG73 flour during 12-month storage. 203
Figure 32. Changes in total phenolics of the flesh and the skin flours of TNG73 during 12-month storage at room temperature and at 4ºC. 204
Figure 33. DPPH inhibition vs concentration of the extract from the flour of the flesh of TNG73 after 1 month of storage at room temperature. 208
Figure 34. General evolution trend of DPPH IC50 of TNG73 flour during 12-month storage. 209
Figure 35. Changes in DPPH IC50 of the flesh and the skin flours of TNG73 during 12-month storage at room temperature and at 4ºC. 210
Figure 36. Correlation between total phenolic content and DPPH IC50. 214
Figure 37. General scheme employed for the extraction of starch from sweet potato. 222
Figure 38. Sponge cakes from sweet potato flour. 224
Figure 39. Compact cookies from sweet potato flour with peanut top. 225
Figure 40. Banana puddings with starch isolated from TNG57 as binder. 226
Figure 41. Questionnaire for sensory evaluation of the new sweet potato products. 228
Figure 42. Representative viscograms of starches extracted from sweet potato cultivars. 232
Figure 43. Representative viscograms of flours of sweet potato cultivars. 235

List of Tables
Table 1. Hue angle, color lightness, and color intensity of the fresh samples of sweet potato cultivars TNG57, TNG66, and TNG73 56
Table 2. General composition of 100 g sample dry sweet potato flesh 58
Table 3. Total carotenoids and beta-carotene contents of TNG57, TNG66, and TNG73 61
Table 4. Matrix of 63 treatments issued from a factorial combination of three cultivars with three parts of the root and seven solvents in the second step of the project research 69
Table 5. Structure of the analysis of variance (ANOVA) for DPPH FRSA of the fresh samples 74
Table 6. Interactive effects of the solvent and genotype on total phenolic content of the extract of TNG57, TNG66, and TNG73 76
Table 7. Interactive effects of the solvent, part of the root, and genotype on total phenolic content of TNG57, TNG66, and TNG73 77
Table 8. Interactive effects of the solvent and genotype on the percentage DPPH FRSA of the extracts of TNG57, TNG66, and TNG73 80
Table 9. Interactive effects of the solvent, part of the root, and genotype on the percentage DPPH free radical scavenging activity of the extracts of TNG57, TNG66, and TNG73 82
Table 10. Regression parameters between total phenolics (X) and DPPH FRSA (Y) 83
Table 11. Percentage of DPPH FRSA of TNG57 extracts incubated at 25, 50, 75, and 100ºC 85
Table 12. Percentage of DPPH FRSA of TNG66 extracts incubated at 25, 50, 75, and 100ºC 86
Table 13. Percentage of DPPH FRSA of TNG73 extracts incubated at 25, 50, 75, and 100ºC 87
Table 14. Dry matter content and extraction yield of raw and freeze-dried samples of TNG57, TNG66, and TNG73 100
Table 15. Content of total phenolics and total flavonoids of raw and freeze-dried sweet potato cv TNG57, TNG66, and TNG73 101
Table 16. DPPH IC50 (mg/ml) of raw and freeze-dried sweet potato cv TNG57, TNG66, and TNG73 105
Table 17. ABTS IC50 of raw and freeze-dried sweet potato cv TNG57, TNG66, and TNG73 109
Table 18. Pearson correlation coefficients (R) of total phenolics and total flavonoids with the antioxidant activities 110
Table 19. Changes induced in hue angle, color lightness, and color intensity of sweet potato cultivar TNG57 by the drying process 123
Table 20. Changes induced in hue angle, color lightness, and color intensity of TNG66 by the drying process 125
Table 21. Changes induced in hue angle, color lightness, and color intensity of TNG73 by the drying process1 128
Table 22. Evolution of the total phenolic and flavonoid contents of the flesh of TNG57 during the drying process 131
Table 23. Evolution of the total phenolic and total flavonoid contents of the flesh of TNG66 during the drying process 133
Table 24. Evolution of the total phenolic and flavonoid contents of the flesh of TNG73 during the drying process 136
Table 25. Evolution of the total carotenoids and beta-carotene contents of the flesh of TNG57 137
Table 26. Total carotenoid and beta-carotene contents of TNG66 as affected by the drying process 138
Table 27. Total carotenoid and beta-carotene contents of TNG73 as affected by the drying process 141
Table 28. DPPH FRSA, AOP, and ABTS FRSA of TNG57 as affected by the drying process 143
Table 29. DPPH FRSA, AOP, and ABTS FRSA of TNG66 as affected by the drying process 146
Table 30. DPPH FRSA, AOP, and ABTS FRSA of TNG73 as affected by the drying process 149
Table 31. Matrix of coefficients of correlation (R) among different variables analyzed for TNG57 samples 153
Table 32. Matrix of coefficients of correlation (R) among different variables analyzed for TNG66 samples 154
Table 33. Matrix of coefficients of correlation (R) among different variables analyzed for TNG73 samples 156
Table 34. Regression parameters for relative fit goodness of DPPH, AOP, and ABTS assays in TNG57 157
Table 35. Regression parameters for relative fit goodness of DPPH, AOP, and ABTS assays in TNG66 159
Table 36. Regression parameters for relative fit goodness of DPPH, AOP, and ABTS assays in TNG73 160
Table 37. Catechin, gallic acid, and rutin contents in different fractions of TNG73 180
Table 38. DPPH IC50 of fractions and the crude extract of TNG73 189
Table 39. DPPH IC50 ratios of crude extract to fractions 190
Table 40. Matrix of Pearson coefficients of correlation (R) of DPPH IC50 to catechin, rutin, and gallic acid contents 191
Table 41. Regression parameters for the evolution of the total phenolic content of TNG73 flesh flour during 12-month storage 205
Table 42. Regression parameters for the evolution of the total phenolic content of TNG73 skin flour during 12-month storage 206
Table 43. Regression parameters for the evolution of DPPH IC50 of the flour of TNG73 flesh during 12-month storage 212
Table 44. Regression parameters for the evolution of DPPH IC50 of the flour of TNG73 skin during 12-month storage 213
Table 45. Gelatinization characteristics of starches of TNG57, TNG66, and TNG73 231
Table 46. Gelatinization characteristics of flours of TNG57, TNG66, and TNG73 234
Table 47. Overall acceptance score of the different sweet potato products developed in the framework of this study1 237
Table 48. Taste score of the different sweet potato products developed in the framework of this study 238
Table 49. Flavor score of the different sweet potato products developed in the framework of this study 239
Table 50. Sweetness score of the different sweet potato products developed in the framework of this study 241
Table 51. Texture score of the different sweet potato products developed in the framework of this study 242
Table 52. Softness score of the different sweet potato products developed in the framework of this study 244

References
2020 Africa Conference Advisory Committee (2004) A way forward from the 2020 Africa conference. Statement prepared by the Conference Advisory Committee of the conference on “Assuring Food and Nutrition Security in Africa by 2020: Prioritizing Actions, Strengthening Actors, and Facilitating Partnerships,” held in Kampala, Uganda, April 1–3, 2004. International Food Policy Research Institute (IFPRI), Washington, D.C.
Afanas, E. V., A. I. Dorozhka, A. V. Brodskii, V. A. Kostyuk, and A. I. Potapovitch (1989) Chelating and free radical scavenging mechanisms of inhibitory action of rutin and quercetin in lipid peroxidation. Biochem. Pharmacol. 38(11):1763-1769.
Alderman H., J. Behrman, and J. Hoddinott (2004) Improving child nutrition for sustainable poverty reduction in Africa. International Food Policy Research Institute (IFPRI), Washington, D.C. 6 pp.
Ansari, N. M., L. Houlihan, B. Hussain, and A. Pieroni (2005) Antioxidant activity of five vegetables traditionally consumed by South-Asian migrants in Bradford, Yorkshire, UK. Phytother. Res. 19: 907–911.
AOAC (1970) Official methods of analysis of the association of analytical chemists (11th edn.). AOAC, Washington, D.C., USA. pp. 1015 pp.
AOAC (2000) Official methods of analysis of the association of analytical chemists (17th edn.). Association of Analytical Communities, Gaithersburg, MD, USA.
Arima, H. K. and D. B. Rodriguez-Amaya (1988) Carotenoid composition and vitamin A value of commercial Brazilian squashes and pumpkins. J. Micronutr. Anal. 4: 177-191.
Arima, H. K. and D. B. Rodriguez-Amaya (1990) Carotenoid composition and vitamin A value of a squash and a pumpkin from Northeastern Brasil. Arch. Latinoam. Nutr. 40: 284-292.
Arnao, M. B., A. Cano, and M. Acosta (1999) Methods to measure the antioxidant activity in plant material. A comparative discussion. Free Rad. Res. 31: 89-96.
Arora, A., M. G. Nair, and G. M. Strasburg (1998) Structure-activity relationships for antioxidant activity of a series of flavonoids in liposomal system. Free Radical Biol. Med. 24 (9):1355-1363.
Aruoma O. I. (1993) Free radicals: their role in nutrition. pp. 187-217. In: Aruoma, O. I. (ed.) Free radicals in tropical diseases. Harwood Academic Publishers, London.
Aruoma, O. I. (1994) Nutrition and health aspects of free radicals and antioxidants. Food Chem. Toxicol. 32: 671-683.
Aruoma, O. I. (1998) Free radicals, oxidative stress, and antioxidants in human health and disease. JAOCS. 75: 199-212.
Aruoma O. I. and B. Halliwell (1991) Free radicals and food additives. Taylor and Francis Ltd., London. 119 pp.
Asami, D. K., Y. J. Hong, D. M. Barrett, and A. E. A. E. Mitchell (2003) Comparison of total phenolics and ascorbic acid content of freeze-dried and air-dried marionberry, strawberry, and corn grown using conventional, organic, and sustainable agricultural practices. J. Agric. Food Chem. 51: 1237-1241.
Auerbach, H. R. and D. A. Gray (1999) Oat antioxidant extraction and measurement. Towards a commercial process. J. Sci. Food Agric. 79: 385-389.
Awad, M. A., A. de Jager, L. H. W. van der Plas, and A. R. van der Krol (2001) Flavonoid and chlorogenic acid changes in peel of ‘Elstar’ and ‘Jonagold’ apples during development and ripening. Scientia Hort. 90:69-83.
Bachrach, U. and Y-C Wang (2002) Cancer therapy and prevention by green tea: role of ornithine decarboxylase. Amino Acids. 22: 1-13.
Bartosz, G., A. Janaszewska, D. Ertel, and M. Bartosz (1998) Simple Determination of peroxyl radical-trapping capacity. Biochem. Mol. Biol. Int. 46 (3): 519-528.
BeMiller, J. N. and R. L. Whistler (1996) Carbohydrates. pp. 157-223. In: Fennema O. R. (ed.). Food Chemistry (3rd edn.).
Bendich A. (1990). Carotenoids and the immune system. pp. 323-335. In: Krinsky, N.I., M. M. Mathews-Roth, and R. F. (eds). Carotenoids: Chemistry and Biology. Taylor Plenum Press, NY, USA.
Bendich, A. and J. A. Olson (1989) Biological actions of carotenoids. FASEB J. 3:1927-1932.
Benson, T. (2004) Assessing Africa’s Food and Nutrition Security Situation. IFPRI, Washington, D.C. 6 pp.
Benson, T. (2006) Assessing Africa’s Food and Nutrition Security Situation. IFPRI, Washington, D.C. 4 pp.
Blasco, A. J., M. C. Rogerio, M. C. Gonzalez, and A. Escarpa (2005) Electrochemical index as a screening method to determine total polyphenolics in foods: A proposal. Anal. Chim. Acta. 539: 237–244.
Block, G., B. Paterson, and A. Subar (1992) Fruit, vegetables and cancer prevention: a review of the epidemiological evidence. Nutr. Cancer. 18: l-29.
Bloem, M. W., S. de Pee, and I. Darnton-Hill (1998) New issues in developing effective approaches for the prevention and control of vitamin A deficiency. Food Nutr. Bull. 19: 137 – 148.
Blois, M. S. (1958) Antioxidant determinations by the use of a stable free radical. Nature. 181: 1199- 1200.
Bondet, V., W. Brand-Williams, and C. Berset (1997) Kinetics and mechanisms of antioxidant activity using the DPPH free radical method. Food Sci. Technol. 30: 609-615.
Bonorden, W. R. and M. W. Pariza (1994) Antioxidant nutrients and protection from free radicals. pp. 1948. In: Katsonis, F. N., M. Mackey, and J. J. Hjelle (eds.) Nutritional Toxicology. Raven Press, NY, USA.
Borowska, E. J., A. Szajdek, and J. Borowski (2005) Antioxidant properties of fruits, vegetables and their products. Fruit Proces. 15(1): 38-43.
Bouayed, J., K. Piri, H. Rammal, A. Dicko, F. Desor, C. Younos, and R. Soulimani (2007) Comparative evaluation of the antioxidant potential of some Iranian medicinal plants. Food Chem. 104: 364–368.
Bovell-Benjamin, A. C. (2007) Sweet potato: a review of its past, present, and future role in human nutrition. Adv. Food Nutr. Res. 52:1-59.
Brand-Williams, W., M. E. Cuvelier, and C. Berset (1995) Use of a free radical method to evaluate antioxidant activity. Food Sci. Technol. 28: 25-30.
Britton, G. (1991) Carotenoids. Methods Plant Biochem. 7:473-518.
Brownridge, E. (1993) Food that fights back: antioxidants are nutrition’s newest superheroes. Pharm. Prac. 9:40-50.
Burns, J., P. T. Gardner, D. Matthews, G. G. Duthie, M. E. Lean, and A. Crozier (2001) Extraction of phenolics and changes in antioxidant activity of red wines during vinification. J. Agric. Food Chem. 49: 5797-5808.
Burton, G. W. (1989) Antioxidant action of carotenoids. J. Nutr. 119:109-111.
Burton, G. W. and K. U. Ingold (1984) β-carotene: An unusual type of lipid antioxidant. Science. 224: 569-573.
Byers, T. and G. Perry (1992) Dietary carotenes, vitamin C, and vitamin E as protective antioxidants in human cancers. Ann. Rev. Nutr. 12:139-159.
Cano, A., J. HernKndez-Rulz, E García-Cánovas, M. Acosta and M.B. Arnao (1998) An end-point method for estimation of the total antioxidant activity in plant material. Phytochem. Anal. 9:196-202.
Cano, A., O. Alcaraz, and M. B. Arnao (2003) Free radical-scavenging activity of indolic compounds in aqueous and ethanolic media. Anal. Bioanal. Chem. 376: 33–37.
Cao, G., C.P. Verdon, A.H.B. Wu, H. Wang, and R.L. Prior (1995) Automated assay of oxygen radical absorbance capacity with the Cobas Fara II. Clin. Chem. 41: 1738-1744.
Cao, G., H. M. Alessio, and R.G. Cutler (1993). Oxygenradical absorbance capacity assay for antioxidants. Free Radic. Biol. Med. 14 (3): 303-311.
CGIAR. (2006) Research and Impact: area of research: sweet potato. Retrieved February 6, 2007, from the World Wide Web: [http://www. cgiar.org/ impact/ research/ sweet potato. html.
Chandler, L. A. S. J. Schwartz (1998) Isomerization and losses of trans-carotene in sweet potatoes as affected by processing treatments. J. Agric. Food Chem. 36: 129–133.
CIELab (2003) Ets wine color analysis. (Ets laboratories, 15 October 2003). Retrieved January 1, 2006, from the World Wide Web: http://www. etslabs. com/scripts/ets/ ContentDocs/
CIP (1998) Publications / Annual Report 1998. Diversifying Diets in China. Retrieved March 10, 2007, from the World Wide Web: http:// www. cipotato.org/sweetpotato/.
Cooper, T. G. (1977) The tools of biochemistry (1st edn). John Wiley and Sons, NY, USA. 423 pp.
Council of Agriculture, Executive Yuan, R.O.C. (2006) Sweet potato. Retrieved February 28, 2007, from the world wide web: http://eng.coa.gov.tw/
Craft, N. E. and J. H. Jr. Soares (1992) Relative solubility, stability, and absorptivity of lutein and β-carotene in organic solvents. J. Agric. Food Chem. 40:431-43.
Damodaran, S. (1996) Amino-acids, peptides, and proteins. pp. 321-429. In: Fennema O. R. (ed). Food Chemistry (3rd edn.).
Davies, B. H. (1976) Carotenoids. pp 38-165. In: Goodwin TW (ed). Chemistry and biochemistry of plant pigments (2nd edn.). Academic Press, London.
de Arantes-Frota A. C., A. A. F. de Souza-Lima, A. B. J. Dias, A. C. dos Santos-Lourenço, E. Antecka, and M. N. J. Burnier (2008) Freeze-drying as an alternative method of human sclera preservation. Arquivos Brasileiros de Oftalmologia. 71(2): 137-141.
Diaz, M. N., B. Frei, J. A. Vita, and J. F. Keaney (1997) Antioxidants and atherosclerotic heart disease. N. Engl. J. Med. 337: 408-416.
Dietrich, H., A. Rechner, and C. D. Patz (2004) Bioactive compounds in fruit and juice. Fruit Proces. 14: 50-55.
Di Mascio, P., S. Kaiser, and H. Sies (1989) Lycopene as the most efficient biological carotenoid singlet oxygen quencher. Arch. Biochem. Biophys. 274:532-538.
Di Venere, D., L. V. Sergio, and V. V. Bianco (2005) Antioxidant phenolics in escarole and radicchio during storage of fresh-cut 'ready-to-use' Product. Acta Hort. 682: 1947-1951.
Duvivier P., Hsieh P.-C., Lai P.-Y., and Charles A. L. (2008a) Total phenolic content and antioxidant activity of seven extracts of sweet potato (Ipomoea batatas Lam.) as affected by the extracting solvent and the genotype. Recherche, Etude, développement (RED) 4 (1): 20-27.
Duvivier P., Hsieh P.-C., Lai P.-Y., and Charles A. L. (2008b). Evaluation of drying methods on antioxidant activity, total phenolic and total carotenoid contents of sweet potato (Ipomoea batatas Lam.) var. Tainong 73. J. International Cooperation (JIC) 3(1): 73-86.
Duvivier P., P.-C. Hsieh, P.-Y. Lai, and A. L. Charles (2009) Effect of freeze-drying on phenolic content and antioxidant activity of Tainong 57, Tainong 66, and Tainong 73 cultivars of sweet potato (Ipomoea batatas Lam.). J. International Cooperation (JIC) 4(1): 1-15.
Ehlenfeldt, M. K. and R. L. Prior (2001) Oxygen radical absorbance capacity (ORAC) and phenolic and anthocyanin concentrations in fruit and leaf tissues of high-bush blueberry. J. Agric. Food Chem. 49:2222-2227.
Ekanayake, P. M., G. T. Park, Y. D. Lee, S. J. Kim, S. C. Jeong, and J. Lee (2005) Antioxidant potential of eel (Anguilla Japonica and Conger Myriaster) flesh and skin. J. Food Lipids 12: 34–47.
Elbe, J. H. V., and S. J. Schwartz (1996) Colorants. pp. 651-722. In: Fenema O. R. (ed.). Food Chemistry (3rd edn.).
Etkin, N. L. (1996) Medicinal cuisines: diet and ethnopharmacology. Int. J. Pharmacol. 34: 313–326.
European Parliament (2002) Regulation (EC) No 178/2002 of European Parliament (28 January 2002). 37 pp.
FAO (1984) Production yearbook 1983. FAO, Rome. Retrieved December 2, 2006, from the World Wide Web: http://www.fao.org/ newsroom/ en/ focus.
FAO (2003) Trade reforms and food security. FAO, Rome. 296 pp.
FAO (2004) Understanding food insecurity. The state of food insecurity in the world. FAO, Rome. 43 pp. Retrieved December 2, 2006, from the World Wide Web: http://www.fao.org/ newsroom/en/focus/ 2004/ 51786/ index. html.
FAO (2006a) The state of food insecurity in the world 2005. FAO, Rome. 9 pp. Retrieved October 22, 2006, from the World Wide Web: http://en.wikipedia.org/ wiki/ Food.
FAO (2006b) FAO Contrystat. Repiblik d Ayiti. Retrieved October 21, 2006, from the World Wide Web: http://www.fao.org/ countryProfiles/ default. asp?lang=en
FAO and WHO (2002) Joint WHO/FAO expert consultation on diet, nutrition and the prevention of chronic diseases. WHO technical report series 916. Geneva, 28 Jan.-1 Feb. 2002. Retrieved on Oct. 21, 2006, from the World Wide Web: http://www.who.int/nutrition/topics/ dietnutrition_ and_chronicdiseases/en/print.html
FAOSTAT (2005). Food and Agricultural Statistical Database. Retrieved January 18, 2008, from the World Wide Web: http://faostat.fao.org.
FAO / WHO / UNU (1985) Energy and protein requirements. WHO Technical Report Series 724. Geneva: WHO. 301 pp.
FDA (2006) Federal Food, Drug, and cosmetic act. Retrieved October 21, 2006, from the World Wide Web: http://www.fda. gov/ opacom/ laws/ fdcact/ fdctoc.htm
Fennema, O. R. (1996) Water and Ice. pp. 17-94. In: Fennema O. R. (ed). Food Chemistry (3rd edn.).
Fogliano, V., V. Verde, G. Randazzo, and A. Ritieni (1999) Method for measuring antioxidant activity and its application to monitoring the antioxidant capacity of wines. J. Agric. Food Chem. 1999, 47, 1035-1040.
Folin, O. and V. Ciocalteu (1927) On tyrosine and tryptophane determination in proteins. J. Biol. Chem. 72 (2): 627–650.
Foote, C. S., Y. C. Chang, and R. W. Denny (1970) Chemistry of singlet oxygen X. Carotenoid quenching parallels biological protection. J. Am. Oil Chem. Soc. 92:5216-5218.
Garret, E. H. (2002) Fresh-cut Produce: Tracks and Trends. pp. 1-10. In: in Lamikanra, O. (ed.). Fresh Cut Fruits and Vegetables, Science, Technology, and Market. Florida, USA: CRC Press.
Gerster, H. (1991) Potential role of beta-carotene in the prevention of cardiovascular disease. Int. J. Vit. Nutr. Res. 61:277-291.
Goh, S.H. (1996) Carotene controversy. Malaysian Oil Sci. Technol. 5: 17.
Gomes, K. S. M. (2007) Extração e uso de corantes vagetais da amâzonia no tingimendo do couro da Matrinxiã (Brycon amazonicu, Spix & Agassiz, 1819). Master thesis, Instituto Nacional de Pesquisa da Amâzonia, Universidade Federal da Amâzonias, Brazil.
Goodman, G., E. Thornquist, J. Balmes, M. R. Cullen, F. L. Meyskens Jr, G. S. Omenn, B. Valanis, and J. H. Williams Jr. (2004) The β-carotene and retinol efficacy trial: incidence of lung cancer and cardiovascular disease mortality during 6-year follow-up after stopping β-carotene and retinol supplements. J. Natl. Cancer Inst. 96:1743-1750.
Grabowski, S., M. Marcotte, M. Poirier, and T. Kudra (2002) Drying characteristics of osmotically pretreated cranberries – energy and quality aspects. Drying Technology. 20 (10): 1989-2004.
Gregory III, J. F. (1996) Vitamins. pp. 531-616. In: Fennema O. R. (ed). Food Chemistry (3rd edn.).
Grey, K. F. (1990) The antioxidant hypothesis of cardiovascular disease: epidemiology and mechanisms. Biochem. Soc. Trans. 18: 1041-1045.
Gross, J., R. Ikan, and G. Eckhardt (1983) Carotenoids of the fruit of Overrhoa carambola. Phytochem. 22:1479-1481.
Guo, J.-T., H.-L. Lee, S.-H. Chiang, F. I. Lin, and C.-Y. Chang (2001) Antioxidant properties of the extracts from different parts of broccoli in Taiwan. J. Food Drug. Anal. 9(2): 96-101.
Halliwell, B. and J. M. C. Gutteridge (1989) Free radicals in biology and medicine (2nd edn.). Clarendon Press, Oxford. 543 pp.
Heidhues, F., A. Atsain, H. Nyangito, M. Padilla, G. Ghersi, and J.-C. Le Vallée (2004) Development strategies and Africa’s food and nutrition security. IFPRI, Washington, D C.60 pp.
Heinäaho, M., J. Pusenius, and R. Julkunen-Tiitto (2006) Organic farming methods affect the concentration of phenolic compounds in sea buckthorn leaves. Joint Organic Congress, Odense, Denmark, May 30-31, 2006. Retrieved May 21, 2008, from the World Wide Web: http://orgprints.org/7382/
Hertog, M. G. L., E. J. M. Feskens, P. C. H. Hollman, M. B. Katan, and D. Kromhout (1993) Dietary antioxidant flavonoids and risk of coronary heart disease: Lancet. 342: 1007-1011.
Hendren, E., V. Diaz, and U. Svanberg (2002) Estimation of carotenoid accessibility from carrots determined by an in vitro digestion method. Eur. J. Clin. Nutr. 56: 425–430.
Hertog, M. G. L., E. J. M. Feskens, P. C. H. Hollman, M. B. Katan, and D. Kromhout (1993) Dietary antioxidant flavonoids and risk of coronary heart disease: Lancet. 342: 1007-1011.
Higashi-Okai, K., M. Yamazaki, H. Nagamori, and Y. Okai (2001) Identification and antioxidant activity of several pigments from the residual green tea (Camellia sinensis) after hot water extraction. J. UOEH. 23(4):335-44.
Higby, W. K. A. (1962) A simplified method for determination of some aspects of the carotenoids distribution in natural and carotene fortified orange juice. J. Food Sci. 27: 42–49.
Higley, J. S., S. L. Love, W. J. Price, J. E. Nelson, and K. C. Huber (2003) The rapid visco analyzer (RVA) as a tool for differentiating potato cultivars on the basis of flour pasting properties. Amer. J. Potato Res. 80:195-206.
Hogg, J. S., D. H. Lohmann and K. E. Russell (1961) The kinetics of reaction of 2,2-diphenyl-l-picrylhydrazyl with phenols. Can. J. Chem. 39:1588-1594.
Houghton, P. J. and A. Raman (1998) Laboratory handbook for the fractionation of natural extracts (1st edn). Chapman and Hall, NY, USA. 199 pp.
Howe, P. and S. Devereux (2004) Famine intensity and magnitude scales: A proposal for an instrumental definition of famine. Disasters, 28 (4): 353-372.
Huaman, Z. and D. P. Zhang (1997) Sweet potato. pp. 29-38. In: D. Fuccillo et al. (Eds). Biodiversity in trust – Conservation and use of plant genetic resources in CGIAR centers. Cambridge University Press, Cambridge, UK.
Huang, D.-J., C.-D. Lin, H.-J. Chen, and Y.-H. Lin (2004) Antioxidant and antiproliferative activities of sweet potato (Ipomea batatas [L.] Lam.) ‘Tainong 57’ contituents. Bot. Bull. Acad. Sinica. 45:179-186.
IFPRI (1995) A 2020 vision for food, agriculture, and the environment: The vision, challenge, and recommended action. IFPRI, Washington, D.C. 23 pp.
Islam, M. S., M. Yoshimoto, S. Yahara, S. Okuno, K. Ishiguro, and O. Yamakawa (2002) Identification and characterization of foliar polyphenolic composition in sweet potato (Ipomoea batatas L.) genotypes. J. Agric. Food Chem. 50: 3718-3722.
Jenner, P. (1991) Oxidative stress as a cause of Parkinson’s disease. Acta Neurol. Sand. 84(136): 6-15.
Jung, C. H., H. M. Seog, I. W. Choi, and H. Y. Cho (2005) Antioxidant activities of cultivated and wild Korean ginseng leaves. Food Chem. 92: 535-540.
Kazantzis, G. (2004) Cadmium, osteoporosis and calcium metabolism. Biometals 17 (5): 493-498.
Kazutoshi, O. (2004) Germplasm enhancement and breeding strategies for crop quality in Japan. Genebank, National Institute of Agrobiological Sciences, Japan. Retrieved May 21, 2008, from the World Wide Web: http:www/nias.affrc.go.jp, okusan@affrc.go.jp.
Kendall, P. (2000) Good Food Sources of Antioxidants. Colorado State University, Cooperative Extension.
Kessler, G. J. (2000) The bone density diet. Retrieved on Dec. 2, 2006, from the World Wide Web: http://www.ncbi.nlm.nih.gov/ entrez/ query. fcgi? cmd
Khachik, F., G. R. Beecher, and B. G. Mudlagiri (1991) Separation, identification, and quantification of carotenoids in fruits, vegetables, and human plasma by high performance liquid chromatography. Pure Appl. Chem. 63(1): 71-80.
Kim J.-K., J. H. Noh, S. Lee, J. S. Choi, H. Suh, H. Y. Chung, Y.-O. Song, and W. C. Choi (2002) The first total synthesis of 2,3,6-tribromo-4,5- dihydroxybenzyl methyl ether (TDB) and its antioxidant activity. Bull. Korean Chem. Soc. 23(5): 661-662.
Kim, K. H., R. Tsao, R. Yang, and S. W. Cui (2005) Phenolic acid profile and antioxidant activity of wheat bran and the effect of hydrolysis conditions. Food Chem. 95: 466–473.
KMA, GTZ, and FAO (1998) Post-harvest systems of potato and sweet potato in Kenya - Final report, Nairobi, Kenya - June, 1998.
Kondo, S., K. Tsuda, N. Muto, and J. Ueda (2002) Antioxidative activity of apple peel or flesh extracts associated with fruit development on selected apple cultivars. Sci. Hort. 96:177-185.
Kooijman L. M., K. J. Ganzeveld, R. M. Manurung, and H. J. Heeres (2003) “Experimental Studies on the Carboxymethylation of Arrowroot Starch in Isopropanol-Water Media.” Starch, 55: 495–503.
Kozai, T., C. Kubota, and Y. Kitaya (1996) Sweet potato technology for solving the global issues on food, energy, natural resources, and environmental in 21st century. Environ Control Biol. 34: 105-114.
Krinsky, N. I. (1989) Antioxidant functions of carotenoids. Free Radical Biol. Med. 7:617-635.
Krinsky, N. I. (1990) Carotenoids in medicine. pp. 279-291. In: Krinsky, N.I., M. M. Mathews-Roth, and R. F. Taylor (eds). Carotenoids: Chemistry and biology. Plenum Press, NY, USA.
Krinsky, N. I. (1994) The biological properties of carotenoids. Pure Appl. Chem. 66:1003-1010.
Kuehl, O. R. (1999) Design of experiments: Statistical principles of research design and analysis (2nd edn). Brooks/Cole, Florence, KY, USA. 688 pp.
Kuntz, L.A. (1992) Keeping microorganisms in control. Food Product Design. August: 44-51.
Kurata, R., M. Adachi, O. Yamakawa, and M. Yoshimoto (2007) Growth suppression of human cancer cells by polyphenolics from sweet potato (Ipomoea batatas L.) leaves. J. Agric. Food Chem. 55: 185–190.
Ladislav, F., P. Vera, S. Karel, and V. Karel (2005) Reliability of carotenoid analyses: A review. Curr. Anal. Chem. 1: 93-102.
Lana, M. M. (2006) Effects of cutting and maturity on antioxidant activity of fresh–cut tomatoes. Food Chem. 97(2): 203-211.
Lana, M.M. (2005) Modelling quality of fresh-cut tomato based on stage of maturity and storage conditions. Ph.D. Thesis. Wageningen University. With references and summary in English, Dutch and Portuguese. Horticultural production Chains Group, Plant Science, Wageningen University, Wageningen, The Netherlands. 208 pp.
Lappé, F. M. (1976) Diet for a small planet (2nd edn.) Ballantine Books, NY, USA. 411 pp.
Laranjinha, J. A. N., L. M. Almeida, and V. M. C. Madeira (1994) Reactivity of dietary phenolic acids with peroxyl radicals: antioxidant activity upon low density lipoprotein peroxidation. Biochem. Pharmacol. 48: 487-494.
Larraruri, J. A., C. Sanchez-Moreno, and F. Saura-Calixto (1998) Effect of temperature on the free radical scavenging capacity of extracts from red and white grape pomace peels. J. Agric. Food Chem. 46: 2694–2697.
Larsen, E. and L. P. Christensen (2005) Simple saponification method for the quantitative determination of carotenoids in green vegetables. J. Agric. Food Chem. 53 (17): 6598 -6602.
Lebeau, J., C. Furman, J.-L. Bernier, P. Duriez, E. Teissier, and N. Cotelle. (2000) Antioxidant properties of di-tert-butylhydroxylated flavonoids. Free Radic. Biol. Med. 29(9): 900-912.
Leitão, G.G., S. G. Leitao, and W. Vilegas (2002) Quick preparative separation of natural naphthoquinones with antioxidant activity by high-speed counter-current chromatography. Z. Naturforsch. 57: 1051-1055.
Li, P., H. Anu, S. Jari , Y. Teijo, and V. Heikki (2006) TLC method for evaluation of free radical scavenging activity of rapeseed meal by video scanning technology. In: Proceedings of the 10th International Rapeseed Congress, Camberra, Australia.
Lindsay, R. C. (1996) Flavors. pp. 723-765. In: Fennema O. R. (ed). Food Chemistry (3rd edn.).
Lineback, D. R. and C. H. Ke (1975) Starches and low-molecular -weight carbohydrates from chick pea and horse bean flours. Cereal Chemistry, 52:334-347.
Liu, C. L., Y. S. Chen, J. H. Yan, and B. H. Chang (2008) Antioxidant activity of tartary (Fagopyrum tartaricum (L) Gaerth) and common (Fagopyrum esculentum Moench) buckwheat sprouts. J. Agric. Food Chem. 56:173-178.
Lo, S.-F., S. M. Nalwade, V. Mulabagal, S. Matthew, C.-L. Chen, C. –L. Kuo, and H.-S. Tsay (2004) In vitro propagation by asymbiotic seed germination and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity studies of tissue culture raised plants of three medicinally important species of Dendrobium. Biol. Pharm. Bull. 27(5): 731-735.
Loliger, J. 1991. The use of antioxidants in foods. pp. 121-l 50. In: Aruoma O. I. and B. Halliwell (eds). Free Radicals and Food Additive. Taylor and Francis, London.
Lowry, O H, N. J. Rosebrough, A. L. Farr, and R. J. Randall (1951) Protein measurement with the Folin phenol reagent. J. Biol. Chem. 193: 265-275.
Lu, Y. and L. Y. Foo (2000) Antioxidant and radical scavenging activities of polyphenols from apple pomace. Food Chem. 68: 81-85.
Marc, F., A. Davin, L. Deglène-Benbrahim, C. Ferrand, M.Baccaunaud, P. Fritsch (2004) Méthodes d’évaluation du potentiel antioxydant dans les aliments. Med. Sci. 20: 458-63.
Marinova, D., F. Ribarova, and M. Atanassova (2005) Total phenolics and total flavonoids in Bulgarian fruits and vegetables. J. U. Chem. Technol Metall. 40 (3): 255-260.
Mathews-Roth, M. M. (1985) Carotenoid and cancer prevention — experimental and epidemiological studies. Pure Appl. Chem. 57: 717-722.
Mathews-Roth, M. M. (1991) Recent progress in the medical applications of carotenoids. Pure Appl. Chem. 63: 147-156.
McGee, H. J. (2004) On food and cooking. Scribner. ISBN 0684800012. 896 pp. Retrieved October 21, 2006, from: http://en. wikipedia.org/wiki/ Food#Legal_definition
Meloan, C. E and Y. Pomeranz (1980) Food analysis laboratory experiments, (2nd edn.). The AVI publishing company, Inc. Westport, Connecticut. 157 pp.
Mercadante, A. Z., D. B., Rodriguez-Amaya, and G. Britton (1997) HPLC and mass spectrometric analysis of carotenoids from mango. J. Agric. Food Chem. 45:120-123.
Mercadante, A. Z., G. Britton, and D.B. Rodriguez-Amaya (1998) Carotenoids from yellow passion fruit (Passiflora edulis). J. Agric. Food Chem. 46:4102-4106.
Miliauskas, G., P. R. Venskutonis, and T. A. van Beek (2004) Screening of radical scavenging activity of some medicinal and aromatic plant extracts. Food Chem. 85: 231–237.
Miller, D. D. (1996) Minerals. pp. 617-649. In: Fennema O. R. (ed). Food Chemistry (3rd edn.).
Miller, N. J. and C.A. Rice-Evans (1997) Factors influencing the antioxidant activity determined by the ABTS radical cation assay. Free radical Res. 26:195-199.
Miller, N. J., C. Rice-Evans, M. J. Davies, V. Gopinathan, and A. Milner (1993) A novel method for measuring antioxidant capacity and its application to monitoring the antioxidant status in premature neonates. Clin. Sci. 84: 407-412.
Millward, D. J., Newsholme, E. A. Pellett, P. L. and R. Uauy (1992). Amino acid scoring in health and disease. In: Protein-Energy Interactions - Proceedings of a workshop held by the International Dietary Energy Consultancy Group. Switzerland: IDECG.
Molyneux, P. (2004) The use of the stable free radical diphenylpicrylhydrazyl (DPPH) for estimating antioxidant activity. Songklanakarin J. Sci. Technol. 26(2) : 211-219.
Moure, A., J. M. Cruz, D. Fanco, M. Dominguez, J. Sineiro, H. Dominguez, J. Nunez, and J. C. Parajo (2001) Natural antioxidants from residual sources. Food Chem. 72: 145–171.
Nawar, W. W. (1996) Lipids. pp. 225-319. In: Fennema O. R. (ed). Food Chemistry (3rd edn.).
Muchoki C. N., J. K. Imungi, and P. O. Lamuka (2007) Changes in beta-carotene, ascorbic acid and sensory properties in fermented, solar-dried and stored cowpea leaf vegetables. African Journal of Food, Agriculture, Nutrition and Development (AJFAND) 7(3). Online journal. Accessible at www.ajfand.net
Nagao, T., Y. Komine, S. Soga, S. Meguro, T, Hase, Y. Tanaka, and I. Tokimitsu (2005) Ingestion of a tea rich in catechins leads to a reduction in body fat and malondialdehyde-modified LDL in men. Am. J. Clin. Nutr. 81:122–129.
NRLO. (2001) Functional Foods: Position and future perspectives, report no 2000/15. The Hague, February 2001. ISBN: 90 - 5059 - 121 - 3. 79 pp.
O’Brien, P.J. (1972) The sweet potato: its origin and dispersal. Am. Anthropologist. 74: 343-365.
Ooyanagui, Y. (1984) Re-evaluation of assay methods and established of kit for superoxide dismutase activity. Anal. Biochem. 142:290-296.
Padda M. S. (2006) Phenolic Composition and Antioxidant Activity of Sweetpotatoes [Ipomoea batatas (L.) Lam.]. PhD thesis. Louisiana USA: Louisiana State University and Agricultural and Mechanical College.
Palozza, P, and N. I. Krinsky (1992) Antioxidant effects of carotenoids in vivo and in vitro: An overview. Methods Enzymol. 213:403-420.
Pardey, P. G., J. M. Alston, and R. R. Piggott (2006) Agricultural R&D in the developing world: Too little, too late? International Food Policy Research Institute (IFPRI), Washington, D.C.Washington, DC, USA. 22 pp.
Pariza, M. W. (1996) Toxic substances. pp. 825-840. In: Fennema O. R. (ed). Food Chemistry (3rd edn.).
Picha, D. H. (1985) Crude protein, minerals, and total carotenoids in sweet potatoes. J. Food Sci. 50: 1768-1769.
Pieroni, A. (2000) Medicinal plants and food medicines in the folk traditions of the upper Lucca Province, Italy. J Ethnopharmacol. 70: 235–273.
Pieroni, A., and L. L. Price (2005) Eating and healing: Traditional food as medicine. Haworth Press, Binghamton, NY, USA. 480 pp.
Pieroni, A., C. Nebel, C. Quave, H. Münz, and M. Heinrich. (2002). Ethnopharmacology of liakra: traditional weedy vegetables of the Arbëreshë of the Vulture area in southern Italy. J Ethnopharmacol. 81: 165–185.
Pieroni, A., V. Janiak, C. M. Dürr, S. Lüdeke, E. Trachsel, and M. Heinrich (2002). In vitro antioxidant activity of non-cultivated vegetables of ethnic Albanians in southern Italy. Phytother. Res. 16: 467–473.
Pinstrup-Andersen, P. (2001) The future world food situation and the role of plant diseases. The Plant Health Instructor. [online], 10 (1094). Retrieved October 28, 2006, from: http://en. wikipedia. org/ wiki /Food.
Potter, N. N. (1986) Food science (4th edn.). Avi publishing company, Inc. Westport Connecticut. 735 pp.
Prince, R. L., A. Devine, and S. S. Dhaliwal (2006) Effects of calcium supplementation on clinical fractures and bone structure: Results of a 5-year, double-blind, placebo-controlled trial in elderly women. Arch. Intern. Med. 166: 869-875.
Prior, R. L., G. Cao, A. Martin, E. Sofic, J. McEwen, C. O’Brien, N. Lischner, M. Ehlenfeldt, W. Kalt, G. Krewer, and C. M. Mainland (1998) Antioxidant capacity as influenced by total phenolic and anthocyanin content, maturity, and cultivar of Vaccinium species. J. Agric. Food Chem. 46: 2686-2693.
Puah, C. W., Y. M. Choo, N. A. Ma, and C. H. Chuah (2005) Supercritical fluid extraction of palm carotenoids. Am. J. Environ. Sci. 1 (4): 264-269.
Quackenbush, F. W., and R. L. Smallidge (1986) Nonaqueous reverse phase liquid chromatographic system for separation and quantitation of provitamins A. J. Assoc. Off. Anal. Chem. 69:767-772.
Raina, K., S. Rajamanickam, G. Deep, M. Singh, R. Agarwal, and C. Argawal (2008) Chemopreventive effects of oral gallic acid feeding on tumor growth and progression in TRAMP mice. Mol. Cancer Ther. 7(5):1258–1267.
Raisz, L. (2005) Pathogenesis of osteoporosis: concepts, conflicts, and prospects. J. Clin. Invest. 115 (12): 3318-3325.
Randhir, R. and K. Shetty (2005). Developmental stimulation of total phenolics and related antioxidant activity in light and dark-germinated corn by natural elicitors. Process Biochem. 40: 1721−1732.
Ratti, C. (2001) Hot air and freeze-drying of high-value foods: a review. J. Food Eng. 49: 311-319.
Ravindran, V., G. Ravindran, R. Sivakanesan, and S. B. Rajaguru (1995) Biochemical and nutritional assessment of tubers from 16 cultivars of sweetpotato (Ipomoea batatas L.). J. Agric. Food Chem. 43: 2646-2651.
Rehman, Z., A. M. Salariya, and F. Habib (2003) Antioxidant activity of ginger extract in sunflower oil. J. Sci. Food Agric. 83: 624–629.
Rembiałkowska, E. (2006) Organic food quality – axioms and ambiguities. Paper presented at Joint Organic Congress, Odense, Denmark, May 30-31, 2006.
Ribeiro, S. M. R., J. H. de Queiroz, M. E. L. R. de Queiroz, F. M. Campos, and H. M. S. Pinheiro (2007) Antioxidant in mango (Mangifera indica L.) pulp. Plant Foods Hum. Nutr. 62: 13-17.
Rice-Evans, C., N. J. Miller, and G. Paganga (1995) Structure-antioxidant activity relationships of flavonoids and phenolic acids. Free Radical Biol. Med. 20 (7): 933-956.
Riemersma, R. A., D. A. Wood, C. E. MacIntyre, R. A. Elton, K. F. Grey, and M. F. Oliver (1991) Risk of angina pectoris and plasma concentrations of vitamin A, C and E and carotene. Lancet. 337: l-5.
Rimbach, G., J. Fuchs, and L. Packer (2005) Application of nutrigenomics tools to analyze the role of oxidants and antioxidants in gene expression. pp. 1–12. In: Rimbach, G., J. Fuchs, and L. Packer (Eds.). Nutrigenomics. Taylor and Francis, Boca Raton, FL.
Rodney, J. G. (2004) Antioxidant activity of peanut plant tissues. Master Thesis. Graduate Faculty of North Carolina State University, Department of Food Science. 91 pp.
Rodriguez-Amaya, D. B (2001) A guide to carotenoid analysis in foods. International Life Sciences Institute (ILSI) Press, N.W. Washington, D. C, USA. pp. 71.
Rosegrant, M. W., S. A. Cline, L. Weibo, A. S. Timothy, and A. V.-S. Rowena (2005) Looking ahead long-term prospects for Africa’s agricultural development and food security. IFPRI, Washington, D.C. 75 pp.
Sanchez-Moreno, C., J. A. Larrauri, and F. Saura-Calixto (1998) New parameter for evaluation of free radical scavenging capacity of polyphenols. 2nd International Electronic Conference on Synthetic Organic Chemistry, September 1-30. Retrieved May 21, 2008, from: http://www. mdpi.org/escoc/
Scalbert, A., C. Manach, C. Morand, C. Remesy, and L. Jimenez (2005) “Dietary Polyphenols and the Prevention of Diseases. Crit. Rev. Food Sci. Nutr. 45: 287-306.
Schiedt, K. and S. Liaaen-Jensen (1995) Isolation and analysis. pp. 81-108. In: Britton G., S. Liaaen-Jensen, and H. Pfander (eds). Carotenoids: isolation and analysis, vol 1A. Birkhäuser Verlag, Basel.
Schulzová, V., J. Hajšlová, J. Diviš, and P. Botek. (2006) Organic versus conventional potatoes – is there basis for consumers preference? Paper presented at Joint Organic Congress, Odense, Denmark, May 30-31, 2006.
Schwarz, K., G. Bertelsen, L. R. Nissen,P. T. Gardner, M. L. Heinonen, A. Hopia, T. Huynh-Ba, P. Lambelet, D. McPhail, L. H. Skibsted, and L. Tijburg (2001) Investigation of plant extracts for the protection of processed foods against lipid oxidation. Comparison of antioxidant assays based on radical scavenging, lipid oxidation, and analysis of the principal antioxidant compounds. Eur. Food Res. Technol. 212: 319-328.
Scott, K. J. (1992) Observations on some of the problems associated with the analysis of carotenoids in foods by HPLC. Food Chem. 45:357-364.
Seidel V. (2006) Initial and bulk extraction. pp. 27-46. In: Sarker S. D., Latif Z., and Gray A. I. (eds). Natural products isolation (2nd edn.). Humana Press, NJ, USA.
Shahidi, F. and P. K. J. P. D. Wanasundara (1992) Phenolic antioxidants. Crit. Rev. Food. Sci. Nut. 32: 67-103.


Shimelis E., M. Meaza, and S. Rakshit (2006) Physico-chemical properties, pasting behavior and functional characteristics of flours and starches from improved bean (Phaseolus vulgaris L.) varieties grown in east Africa. Agricultural Engineering International: the CIGR Ejournal. Manuscript FP 05 015. Vol. VIII. February, 2006.
Shimozono, H., M. Kobori, H. Shinmoto, and T. Tsushida (1996) Suppression of the Melanogenesis of Mouse Melanoma B16 Cells by Sweet Potato Extract. J. Jap. Soc. Food Sci. Technol. 43: 313-317.
Sies, H. (1991) Oxidative Stress: Introduction. pp. 15-22. In: Sies, H. (ed.). Oxidative stress: Oxidants and antioxidants. Academic Press, London.
Slater, T. F. (1989) Free radicals in medicine. Free Radical Res. Commun. 7: 119-390.
Smith, M. A., G. Perry, P. L. Richey, L. M. Sayre, V. E. Anderson, M. F. Beal, and N. Kowal (1996) Oxidative damage in Alzheimer's. Nature. 382: 120-121.
Staessen, J., H. Roels, D. Emelianov, T, Kuznetsova, L. Thijs, J. Vangronsveld, and R. Fagard (1999) Environmental exposure to cadmium, forearm bone density, and risk of fractures: prospective population study. Public Health and Environmental Exposure to Cadmium (PheeCad) Study Group. Lancet 353 (9159): 1140-1144.
Stavric, B. and T. I. Matula (1992) Flavonoids in foods: their significance for nutrition and health. pp. 274-294. In: Ong, A. S. H. and L. Packer (eds.). Lipid-Soluble Antioxidants: Biochemistry and Clinical Applications. Birkhluser, Basel.
Steinmetz, K. A. and J. D. Potter (1996) Vegetables, fruit and cancer prevention: a review. J. Am. Diet. Assoc. 96: 1027 – 1039.
Stock J. S. (1939) A method of graphic interpolation. J. Am. Stat. Ass. 34 (108): 709-713.
Suda, I., S. Furuta, Y. Nishiba, O. Yamakawa, K. Matsugano, and K. Sugita (1997) Reduction of liver injury induced by carbon tetrachloride in rats administered purple-colored sweet potato juice. J. Jap. Soc. Food Sc. Technol. 44: 315-318.
Teow, C. C., V.-D. Truong, R. F. McFeeters, R. L. Thompson, K. V. Pecota, G. C.Yencho (2007) Antioxidant activities, phenolic, and β-carotene contents of sweet potato genotypes with varying flesh colors. Food Chem. 103: 829–838.
Terão, J. (1989) Antioxidant activity of ß-carotene-related carotenoids in solution. Lipids. 24:659-661.
Tonucci, L. H., J. M. Holden, G. R. Beechert, F. Khachik, C. S. Davis, and G. Mulokozi (1995) Carotenoid content of thermally processed tomato-based food products. J. Agric. food Chem. 43: 579-586.
Tsai, P. J., L. Delva, T. Y. Yu, Y. T. Huang, and L. Dufossé (2005) Effect of sucrose on the anthocyanin and antioxidant capacity of mulberry extract during high temperature heating. Food Res. Int. 38: 1059–1065.
Turkmen, N., F. Sari, and S. Velioglu (2005) The effect of cooking methods on total phenolics and antioxidant activity of selected green vegetables. Food Chem. 93: 713-718.
UNICEF (2006) UNICEF analysis of the number of underweight children in the developing world. UNICEF, NY, USA. 36 pp.
United Kingdom Office of Public Sector Information (1990) Food Safety Act 1990 (c. 16). (1990). 11 pp. Retrieved October 21, 2006, from: http://www.opsi.gov.uk/acts/acts1990/ ukpga_ 19900016.
USDA (1975) Composition of foods, USDA, Washington, D.C. 49 pp.
van Poppel, G. (1993) Carotenoids and cancer: an update with emphasis on human intervention studies. Eur. J. Cancer. 29A: 1335 – 1344.
Vinson, J.A., Y. Hao, X. Su, and L. Zubik. 1998. Phenol Antioxidant Quantity and Quality in Foods: Vegetables. J. Agric. Food Chem. 46: 3630-3634.
von Elbe J. H. and S. J. Schwartz (1996) Colorants. pp. 661-672. In: Fennema O. R. (ed.). Food chemistry (3rd edn.). Marcel Dekker, Inc., NY, USA.
Walkowiak-Tomczak, D. (2007) Changes in antioxidant activity of black chokeberry juice concentrate solutions during storage. Acta Sci. Pol., Technol. Aliment. 6(2): 49-55.
Walter, W.M. and W.E. Schadel (1981) Distribution of phenols in ‘Jewel’ sweet potato [Ipomoea batatas (L.) Lam.] roots. J Agric Food Chem. 29: 904-906.
Wanda, W. C. (1995) Sweet potato. Retrieved Februar 13, 2007, from the World Wide Web: http://www.hort.purdue.edu/newcrop/ crop fact sheets/ sweetpotato.html.
Wang, C. C., C. Y. Chu, K. O. Chu, K. W. Choy, K. S. Khaw, M. S. Rogers, and C. P. Pang (2004) Trolox-equivalent antioxidant capacity assay versus oxygen radical absorbance capacity assay in plasma. Clin. Chem. 50:952-954.
Wayner, D. D. M., G.W. Burton, K. U. Ingold, and S. Locke (1985) Quantitative measurement of the total peroxyl radical-trapping antioxidant capability of human blood plasma by controlled lipid peroxidation. FEBS Letters. 187: 33-37.
Westman, E. C. (2002) Is dietary carbohydrate essential for human nutrition? Am. J. Clin. Nutr. 75 (5): 951-953.
WFP (2006) Breaking out of the poverty trap. How do we use food aid. Retrieved October 22, 2006 from: http://en. wikipedia. org/wiki/Food#
Whitaker, J. R. (1996) Enzymes. pp. 431-530. In: Fennema O. R. (ed). Food Chemistry (3rd edn.).
WHO/UNICEF (1995) Global prevalence of vitamin A deficiency. WHO micronutrient deficiency information system (MDIS), Working Paper no 2, WHO/NUT/95.3. WHO, Geneva. 116 pp.
Wilhelmina, K., C. F. Forney, A. Martin, and R. L. Prior (1999) Antioxidant capacity, vitamin C, phenolics, and anthocyanins fresh storage of small fruits. J. Agric. Food Chem. 47: 4638-4644.
William, P. J. and A. K. Douglas (2006) Extraction of plant secondary metabolites. pp. 323-351. In: Satyajit DS, Zahid L, Alexander IG (eds). Natural product isolation (2nd edn.). Humana Press, NJ, USA.
Woolfe, J. (1993) Sweet potato: An untapped food resource. Cambridge University Press, Cambridge, USA. 179 pp.
World Bank (1997) World Development Report 1997. The state in a changing world. Oxford University Press for the World Bank, NY, USA. 18 pp. Retrieved October 21, 2006, from http://www.worldbank. org/html.
World Bank (2004) World development indicators 2004. Washington, D.C., USA. 400 pp.
Yagasaki, K., Y. Miura, R. Okauchi, and T. Furuse (2000) Inhibitory effects of chlorogenic acid and its related compounds on the invasion of hepatoma cells in culture. Cytotechnology 33: 229-235.
Yamakawa, O. and M. Yoshimoto (2002) Sweet Potato as Food Material with Physiological Functions. Acta Hort. 583: 179-184
Yap, S.C. (1995) Palm oil carotenes: Chemistry and technology. Ph.D. Thesis, University of Malaya, Kuala Lumpur. 94 pp.
Yen, D. E. (1982) Sweet potato in historical perspective. pp. 17–30. In: Villareal R.L. and T.D. Griggs (Eds.). Sweet potato, proceedings of first international symposium, AVRDC Publ. No. 82-172, Tainan, Taiwan.
Yen, G.-C., P.-D. Duh, and C.-L. Tsair (1993) Relationship between antioxidant activity and maturity of peanut hulls. J. Agric. Food Chem. 41: 67-70.Yoshikawa, T. (1993) Free radicals and their scavengers in Parkinson’s disease. Eur. Neural. 33( I): 6 and 68.
Zaidul, I. S. M., N. A. N. Norulaini, A. K. M. Omar, H. Yamauch, and T. Noda (2007) RVA analysis of wheat flour and potato, sweet potato, yam, and cassava starches. Carbohydrate Polymers. 69: 784-791.
Zechmeister, L. (1960) Cis-trans isomeric carotenoid pigments. vol. 18. pp. 223-334. In: Zechmeister, L. (Ed). Progress in chemistry of organic natural products, Springer-Verlag, Wien.
Zhang, D., J. Cervantes, Z. Huaman, E. Carey, and M. Ghislain (2000) Assessing genetic diversity of sweet potato (Ipomoea batatas (L.) Lam.) cultivars from tropical America using AFLP. Genet. Resour. Crop Ev. 47: 659–665.
Zhu, Q.Y., R. M. Hackman, J. L. Ensunsa, R. R. Holt, and C. L. Keen (2002) Antioxidative activities of oolong tea. J. Agric. Food Chem. 50: 6929-6934.
Ziegler, R. G. (1991) Vegetables, fruits, and carotenoids and the risk of cancer. Am. J. Clin. Nutr. 53: 251S-259S.