Resistant Starch Content, Starch Digestibility and the Fermentation of Some Tropical Starches In Vitro

Abstract

Tropical starches including cereal starches (waxy, non-waxy rice and maize), legume starch (mung beans), tuber starches (potatoes, edible cannas, taros and tapiocas) and starchy fruit (unripe bananas) were investigated for their resistant starch (RS) content, thermal properties by differential scanning calorimetry, starch digestibility and the production of short chain fatty acids (SCFAs) through fermentation processes in the colon by an in vitro method. Two commercial high-fibre modified starches from corn and tapioca were also investigated for comparison. It was found that RS content of the samples varied from 10 to 52 g/100 g dry sample. All starch samples showed a single endothermic peak located broadly around 60–99 °C except both the commercial modified starches. The starch samples also exhibited as the very rapidly digested starch resulting in high values of predicted glycaemic index, ranging from 53 to 94. In vitro fermentation of the starch samples showed that SCFA production increased as the RS content of the samples increased.