Prebiotic Effects of Colocasia esculenta Starch on the Nutritional, Physicochemical and Microbial Properties of Yogurt

Abstract

Native cocoyam (Colocasia esculenta) was modified using heat moisture conditioning process to obtain Resistant Starch (RS). The native and modified starch samples were used to partially replace the milk content of yogurt at three different levels (0.5, 1.0 and 1.5%). The stirred yogurt samples produced were analyzed for proximate and mineral compositions, physicochemical, and microbial properties using standard methods. The results showed that the yogurt samples with native and modified starches had 76.89 - 82.09, 2.64 - 2.87, 5.39 - 5.55, 0.75-0.78, and 8.72 - 14.34% moisture, fat, protein, ash and carbohydrate, respectively while the control sample had 85.92, 3.02, 5.64, 0.79, 4.63% carbohydrate, respectively. The mineral content, pH, total soluble solids, syneresis of the yogurt samples decreased with increases in the addition of native and resistant starches while the titratable acidity and lactic acid bacteria count increased. During storage at refrigerated temperature, the pH and lactic acid bacteria count decreased while titratable acidity, total soluble solids and syneresis increased. The yogurt sample with 1.5% resistant starch had the least fat content, highest viscosity, lowest rate of syneresis and highest lactic acid bacteria count.