Enzyme-Resistant Dextrin from Chinese Yam Starch for Potential Application in Beverage Industry: Preparation, Physicochemical Properties and In Vitro Digestion

Preparation conditions, physicochemical properties and in vitro digestibility of enzyme-resistant dextrin from Chinese yam starches, which are native, easily accessible and cheap raw materials in China, were investigated in the current study. The results showed that the enzyme-resistant fraction content in enzyme-resistant dextrin increased and the whiteness of the enzyme-resistant dextrin decreased with the increasing concentrations of hydrochloric and citric acids and the rising heating temperatures, and the prolonged heating times. Considering the manufacturing cost and the beneficial usage, the enzyme-resistant dextrin produced by heating of Chinese yam starch in the presence of hydrochloric (0.11% dsb) and citric (0.2% dsb) acids at 150°C for 60min was selected. Enzyme-resistant dextrin had a low molecular weight of about 6800 Da and rich “non-digestible” α-1,2 glycosidic bond and was well-soluble in water, stable at pH 3.0–7.0 or after heating at 85°C for 0.5 h showed, high thermal stability and high resistant to the artificial gastric juice and small intestinal fluids. These characteristics make the selected enzyme-resistant dextrin suitable for use in the soft drink industry as the soluble dietary fibres and prebiotics in the beverages. This would provide an excellent opportunity to reduce the caloric value of the beverages and exert a beneficial effect on the intestinal microflora of people consuming beverages enriched with enzyme-resistant dextrins.