Effect of ultrasound-assisted enzyme pretreatment on γ-aminobutyric acid content, eating quality and starch properties of germinated brown rice

A novel technique has been developed to increase γ-aminobutyric acid levels and enhance the quality of germinated brown rice (GBR) by ultrasound and enzyme treatment. The combined use of ultrasonic and enzyme treatments notably enhanced the germination rate of brown rice. Additionally, the γ-aminobutyric acid content substantially improved from 18.79 ± 1.87 mg/100 g to 38.60 ± 3.19 mg/100 g when compared to the untreated group. Moreover, the cracks produced on the GBR surface and disruption of the starch structure resulted in increased water absorption, shortening of cooking time, and reduction in GBR hardness, thereby improving the cooking and edible quality of GBR. Additionally, ultrasonic and enzyme treatments increased the amount of fast-digestible starch and enhanced starch digestibility. However, they had minimal impact on the crystal structure, degree of crystallinity, and heat energy changes during the starch pasting process of GBR.