Effects of conventional and microwave pretreatment acetylation on structural and physicochemical properties of wheat starch

Abstract

SummaryThe changes in structural and physicochemical properties of wheat starch after conventional and microwave pretreatment acetylation process were investigated and compared. The microscopy analysis showed that the microwave pretreatment acetylation significantly influenced the surface and interior structure of starch granules compared with the conventional acetylation. The microwave pretreated and untreated starch granules retained the A‐type crystalline structure with decreased relative crystallinity after acetylation. The microwave pretreated starch showed higher degree of substitution, acetyl content, and gelatinisation and pasting temperatures than those of the untreated starch after acetylation under the same conditions. However, the microwave pretreated starch showed lower gelatinisation enthalpy, light transmittance, and peak viscosity compared with the untreated starch after acetylation. Furthermore, water solubility and swelling power of the microwave pretreated and untreated starch increased after acetylation. Generally, the microwave pretreatment acetylation significantly modified structural and physicochemical properties of wheat starch compared with single acetylation process. Therefore, a combination of microwave pretreatment with acetylation can be suggested for modification of wheat starch to promote its applications in the food and nonfood industries.