Physicochemical properties of infrared heat-moisture treated wheat starch

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.