Measurement and comparison of multi-scale structure in heat and pressure treated corn starch granule under the same degree of gelatinization

Abstract

In order to popularize the application of high hydrostatic pressure (HHP) in staple food, the different impact of HHP (from 300 to 600 MPa) and heat treatment (from 60 to 75 °C) on corn starch (80 wt%) under the same DG was investigated. Granule morphology, crystalline characteristics, short-range ordered structure and lamellae structure was examined with a combination of SEM, CLSM, XRD, ATR-FTIR, and SAXS. Results obtained demonstrated Heat-Treated starch appeared endo- and exo-corrosion with more collapses and destructiveness, whereas just endo-corrosion with a dense periphery was induced by HHP. Under the same degree of gelatinization (DG), the long-range and short-range structure sustained more ordered in Pressure-Treated starch than Heat-Treated starch. Further, Heat-Treated starch exhibited more flawed semi-crystalline lamellae. The larger DG, the thicker amorphous lamellae thickness (da) of Heat-Treated starch and Pressure-Treated starch was. Moreover, when DG up to 70%, the increase of da in Heat-Treated starch was more obvious. Heat treatment was shown to be more severe than HHP to disrupt the lamellae. The loss of semi-crystalline structure order occurs more violent than crystalline structure for corn starch. It is of value to reveal that heat and HHP treatment led to similar change trend for multi-scale structural features, whereas the change extent was quite various. This study was potential to provide a theoretical basis to improve the quality of novel starch-based food.