Comparative analysis of nutrient composition and glycaemic indices of nine sweet potatoes (Ipomoea batatas) varieties

Abstract

Sweet potatoes are one of the major tuberous roots consumed around the world. The objective of the present study was to determine the nutritional composition, glycaemic indices and glycaemic loads of selected Sri Lankan sweet potato varieties, in order to address the inadequacy of information and the controversial findings on glycaemic indices. Nutrient composition (moisture, ash, digestible carbohydrates, dietary fiber, crude protein and fat) of boiled sweet potatoes, GI and glycaemic loads (GL) of nine varieties were determined using standard methods. Digestible carbohydrate content ranged between 29-88% on dry weight. Ash, crude protein and crude fat contents of the varieties ranged between 3.1-5.0%, 3.0-5.9% and 2.6-5.3% on dry weight basis (DW) respectively. The total dietary fiber content was above 9.5% DW in the studied varieties. Moisture content of boiled sweet potato tubers were 72-81% on fresh weight basis and both the GIs (86-119) and GLs (>20) were high. However, the GL reduced to medium or low when considering an actual edible portion for all the varieties except for two varieties. Sweet potatoes are a good source of highly available carbohydrates which elicit high GIs.