Structure and Physicochemical Properties of Resistant Starch Prepared by Autoclaving-Microwave

This work is focused on evaluating the structure (granular morphology, crystalline structure, molecular order structure), and properties (resistant starch content, swelling power, amylose leaching) of resistant starch (RS) prepared from corn starch by an autoclaving and autoclaving-microwave method. The results indicated that compared with native starch, all of the RS granules became loose, bigger, and rough fragmented, and displayed a B+V crystalline structure. Meanwhile, the relative crystallinity, helix content, molecular orders for RS samples decrease. The RSs displayed mainly RS3 and RS5 types, with enhanced thermal stability. Compared to autoclaving method, the autoclaving-microwave treatment significantly increases the RS content from 30.15% to 40.70%, since microwave could promote the formation of the double helix in RS. In particular, the RS prepared by autoclaving-microwave (HRS-CM) exhibits the highest degree of crystallinity, ordered structure, and degree of double helical structure as confirmed by XRD, FT-Raman, and C-13 NMR.