Effect of microwave irradiation-retrogradation treatment on the digestive and physicochemical properties of starches with different crystallinity

The effect of microwave irradiation-retrogradation (MIR) treatment on the physicochemical properties and in vitro digestibility of corn starch (A-type crystallinity), potato starch (B-type) and chestnut starch (C-type) were evaluated. After MIR treatment, the amount of resistant starch (RS) increased and rapid digestible starch (RDS) decreased along with the retrogradation time in all three starches. The degree of retrogradation (DR) of starch was significantly positive correlated with amylose and RS content. All three starches subjected to MIR treatment exhibited a B-type crystalline structure. With the increase in retrogradation time, starch granules became more orderly. The DR was significantly positively correlated with relative crystallinity of X-ray pattern, T_o, ΔH of thermal properties, and the Fourier transform infrared ratio of 1047/1022 cm^-1 of starch. The results indicated that MIR treatment is a good industrial method for preparing low digestive starch and retrogradation time is an important parameter for the process.