Physical properties and enzyme susceptibility of rice and high-amylose maize starch mixtures.

Resistant starch has promising health benefits and possesses great potential as a functional ingredient in diverse food formulation and production. Here, 10-50% high-amylose maize starch with 70% amylose content (H7) representing type 2 resistant starch was incorporated into three types of rice starch with varying amylose content (1.6-32%). Thermal properties, rheology, and enzyme susceptibility to porcine pancreatic α-amylase of the starch mixtures were analyzed. Addition of H7 at levels of 10-50% decreased the yield stress and consistency coefficient of rice starches for the flow properties as modeled by the Herschel-Bulkley equation. Dynamic rheological analysis showed that addition of H7 decreased the storage modulus during heating and increased it during cooling and frequency sweeping for all rice starches tested. Gelatinization, retrogradation, and enzyme susceptibility of the resulting mixtures appeared additive of that of individual components. A desirable reduction in the digestibility of starchy foods could be achieved by adding high-amylose maize starch. The physical modifications in properties of the starch blends are dependent on the addition level of resistant starch.