Physicochemical properties of infrared heat-moisture treated wheat starch

摘要

In this study, wheat starch was tempered to 20 or 30% moisture content and infrared (IR) treated at 550 or 730W for 30, 60, 90 min. Infrared-treated wheat starch samples mostly retained birefringence and typical A-type diffraction pattern. Intensity of a new peak (at 2 theta = 20 degrees) slightly increased as the IR power increased. Relative crystallinity values decreased after the infrared treatment, especially at the higher moisture content (30%) or IR power (730 W). Significant increases in T-o, T-p, and T-c-T-o values and decrease in Delta H were observed after the infrared treatment (p 0.05). Remarkable changes in thermal properties were observed for the starch samples treated at higher moisture contents. Decrease observed in retrogradation enthalpies of the infrared-treated wheat starches after 7 days of storage was not significant. Infrared treatment at 30% moisture content and 550 or 730W caused decreases in viscosity values. The sample treated at 30% moisture content and 730W for 90 min gave the lowest viscosity values. Results of the present study were consistent with the results of the literature using conventional heat-moisture treatment methods and this revealed that infrared heat-moisture treatment may provide an alternative route for modification of wheat starch in a shorter time.