Comparative Study of Starch Characteristics, In-Vitro Starch Digestibility and Glycemic Index of Some Starchy Foods Consumed in Nigeria

Abstract

The study investigated the carbohydrate characteristics and in-vitro starch digestibility of some starchy food consumed in Nigeria. Ten foods samples (cassava, yam, red and white sorghum, rice, plantain, banana, semovita, noodles and bread) were selected. The content of starch, amylose and sugar were determined by colorimetric method, in vitro rate of starch hydrolysis was evaluated by multi-enzyme digestion method over a period of two hours, the glucose released was estimated by colorimetric method and was compared to the reference food (bread). The result showed that the percentage moisture content and total starch ranged from 9.8 to 15.3% and 236 to 248 mg/g, while amylose, Rapidly Digestible Starch (RDS) and Resistance Starch (RS) ranged from 8.41 to 19.2%, 30.8 to 51% and 7.8 to 37.4%, respectively. The in-vitro digestibility study indicated that the equilibrium Concentration (C?), Kinetic constant (K ), Hydrolysis Index (HI) and Glycemic Index (GI) ranged from 34 to 64.9, and 0.02 to 0.07, 56.6 to 104 and 71 to 96.8, respectively. Positive correlations (P < 0.05) exist between RDS and GI (r = 0.700) and RS and amylose (r = 0.899) The study revealed that, structure of dietary carbohydrate could greatly influenced the Glycemic Index, plantain and noodles with low RDS and low hydrolysis constant may be beneficial in management of diabetes whereas sorghum, semovita, cassava and bread with high RDS, and high GI should be taken sparingly or combined with high protein and low glycemic load foods.