Effect of microwave heat/moisture treatment on physicochemical properties of Canna edulis Ker starch

Abstract BACKGROUND: Microwave heat/moisture treatment (MWT) is being used increasingly in food processing, but very little research has been carried out on its effect on tuber starches. In this study, Canna edulis Ker tuber starch was subjected to MWT with moisture contents ranging from 20 to 45% (w/w), and the effects of MWT on the physicochemical properties of the starch, including the extent of amylose leaching, enzymatic digestibility, X‐ray diffraction (XRD) and differential scanning calorimetry (DSC) characteristics, were determined. RESULTS: In the process of MWT, temperature exhibited a positive correlation with microwave power and moisture content. When amylose leaching was used as an index, a moisture content of 40%, a treatment time of 15 min and a microwave power of 800 W were found to be the optimal conditions for MWT of C. edulis starch. The enzymatic digestibility changed under different treatment conditions. Furthermore, XRD measurements revealed a change in crystalline structure from type B to type A and an increased degree of crystallinity. Thermal (DSC) studies showed higher values of T o , T p and T c of endothermic peaks, and exothermic peaks were also observed. CONCLUSION: MWT increased the degree of crystallinity, resulting in more resistant fractions in C. edulis starch, which will be beneficial to human health. Copyright © 2009 Society of Chemical Industry