New insights into gelatinization mechanisms of cereal endosperm starches

Abstract

A thorough understanding of starch gelatinization is needed to control starch functional properties for food processing and human nutrition. Here, we reveal the mechanism of structural disassembly of rice, maize and wheat starch granules during thermal transitions in which a Rapid Visco Analyzer (RVA) was used to pre-heat the starches to certain transition points in the differential scanning calorimetry (DSC) heating profiles. This was done to generate sufficient material for structural analyses. The results from DSC, Raman, X-ray diffraction and scanning electron microscopy (SEM) analyses all showed that at the conclusion temperature (T_c) of the DSC endotherm rice starch gelatinization was complete, whereas residual structural order remained in maize and wheat starches. Gelatinization of wheat and maize starch was complete at a temperature higher than T_c in the profile, which we define as the end temperature (T_e). We propose that T_e would be better to define the completion point of starch gelatinization than T_c.