Effect of Some Preliminary Processing Techniques on Nutrients, Anti-nutrients, Mineral and Vitamin Composition of Four Varieties of Nigerian Sweet Potato [Ipomoea Batatas L. (Lam.)]

ABSTRACT Effects of preliminary processing techniques such as peeling, washing, cutting, slicing and drying on chemical composition of sweet potato were studied. Generally there were increases in protein, fat, carbohydrates, ash, fiber and sugars. Calcium, potassium and magnesium contents were increased in all samples. Iron contents were increased as much as 37% to 88%, zinc 7% to 9%, copper 252% to 333%. Vitamin C contents were reduced by 46% and 52%. Thiamine contents increased by between 14% and 100%. Riboflavin and Niacin were greatly increased for all samples. β-carotene contents were increased between 17% and 72%. Tannin was the only anti-nutrient found. It was observed to have reduced in all samples between 66% and 70%. The results of this study may help in understanding changes in nutrition during preliminary processing and therefore preservation of food quality. Abbreviations: Orange fleshed sweet potato (OFSP); Purple fleshed sweet potato (PFSP); Yellow fleshed sweet potato (YFSP); White fleshed sweet potato (WFSP); Association of Official Analytical Chemists (AOAC); Trypsin Inhibition Activity (TIA); Analysis of Variance (ANOVA); Statistical Packages for Social Sciences (SPSS); Duncan’s Multiple Range Test (DMRT); International Union of Food Science and Technology (IUFosT); United States Potato Board (USPB), ND (Not Detected).