Abstract:The effects of exogenous γ-aminobutyric acid (GABA) combined with ultrasonic treatment on the structural characteristics and glycemic index fluctuations of mung bean starch during germination were studied, and mung bean starch products with low glycemic index values were acquired. Mung bean starch was examined after different germination times using various analysis methods including scanning electron microscopy, X-ray diffraction, and Fourier infrared spectroscopy. The results demonstrate that the total starch content of the mung beans decreased from 52.13%~21.18% after 96 h of germination. Moreover, after 12 h of germination, the resistant starch content reached 70.65%. The morphology of the mung bean starch granules did not change significantly during germination. After 96 h of germination, the relative crystallinity of the mung bean starch decreased from 39.64%~12.72%, but germination did not alter the crystal type of the mung bean starch. After germination, no new functional groups were produced, but the orderliness of the starch crystal structure was reduced. After germination, the retrogradation of the mung bean starch was enhanced, and its digestive resistance also increased. After 12 h of germination, the estimated glycemic index of the germinated mung bean starch reached 22.52, indicating that germination can slow the increase of the glycemic index of mung bean starch compared with untreated counterparts (which had a glycemic index of 27.13). Exogenous GABA combined with ultrasonic treatment reduced the total starch content while increasing the resistant starch content, and the digestive characteristics of the mung bean starch was remarkably modified. These finding provide a theoretical basis for the application of mung bean starch in functional foods.
