The influence mechanism of brown rice starch structure on its functionality and digestibility under the combination of germination and zinc fortification

Abstract

This study explored the influence of germination and fortification on the functionality and digestibility of brown rice from the perspective of starch structure changes. The surface of germinated brown rice starch appeared some pits and holes under the action of endogenous hydrolase, and the amylose content, relative crystallinity and short-range order of the starch decreased significantly after germination. However, the fortification treatment seemed to intensify the enzymatic hydrolysis of germinated brown rice starch, showing deeper pits, lower short-range order and less double helix structure. These changes in structural characteristics led to a significant decrease in peak viscosity, enthalpy change (ΔH) and starch hydrolysis rate after germination and fortification treatment. As the germination time increased, the trend became more obvious. And the peak viscosity and enthalpy change (ΔH) of fortified brown rice reached the minimum values of 290.89 cP and 13.73 J/g after 34 h of germination, respectively, while the starch hydrolysis rate reached the maximum value of 85.42 %. Overall, the combination of germination and fortification could be an effective method to adjust the functional and digestive characteristics of starch by changing its structural characteristics.

Keywords: Brown rice; Digestibility; Functionality; Germination; Structure; Zinc fortification.