Characterization of rice starch gels reinforced with enzymatically-produced resistant starch

Abstract

Enzymatically-modified resistant starch (RS) was prepared by amylosucrase (ASase) reaction and was applied to develop structurally strengthened rice starch gels. Effects of ASase-modified and commercial RSs were examined for textural and physicochemical properties of rice starch gels. Rice gel hardness increased up to 60% with the presence of ASase-modified RS; the increase was proportional to the substitution level. Gel cohesiveness seemed to decline significantly, while springiness kept intact when RSs were added. A slight decrease in elasticity was observed for the sample with 20% (w/w) of ASase-modified normal corn starch, while 2-5 times higher RS content in this sample was obtained compared to untreated gel. Rice starch gels reinforced with ASase-modified RS decreased up to 40% of water exudation from gel structure, and intact morphological structure was observed after 7-day storage. These results suggested that ASase-modified RS would be applicable for producing rice starch gel foods as a texture enhancer and a functional ingredient.