Effects of continuous and intermittent retrogradation treatments on in vitro digestibility and structural properties of waxy wheat starch

The effects of continuous retrogradation (CR) and intermittent retrogradation (IR) treatments under 4 °C and 25 °C or temperature-cycled condition of 4/25 °C on the digestibility and structural properties of waxy wheat starch were investigated. The results indicated that IR treatment under temperature cycles of 4/25 °C (IR-4/25) was more beneficial to the formation of slowly digestible starch (SDS, 42.24%). Moreover, the gelatinisation enthalpy of IR-4/25-treated starch sample was lower than that of CR-4/25-treated sample. Variation in infrared absorbance ratio of 1047 cm−1/1022 cm−1 of IR-treated starch samples was consistent with relative crystallinity. Through retrogradation treatment under 4/25 °C or 4 °C, starch samples exhibited X-ray diffraction pattern of B-type, while CR-25 and IR-25-treated samples showed a mixed A + B type pattern. Besides, the swelling power of CR-4/25-treated starch sample was higher than that of IR-4/25-treated sample. The pasting temperatures of IR-treated starch samples were higher than those of the CR-treated samples.