Effects of Pretreatment Methods on the Quality of Rice Bran Ferment

In order to study the effect of the treatment of ultrasound, microwave and baking on the quality of rice bran ferment after fermentation, rice bran was used as raw materials, Saccharomyces cerevisiae and Lactobacillus plantarum were used as fermentation strains. Based on the effects of fermentation time, fermentation temperature, and inoculation amount on the content of γ-aminobutyric acid content and pH in rice bran ferment, orthogonal experiments were used to obtain optimal conditions for rice bran ferment. Then, the rice bran raw materials were processed under different process conditions of ultrasound, microwave and baking, and the effects of different pretreatment methods on the rice bran ferment were compared. The results showed that the optimal fermentation conditions for rice bran ferment were as follows: fermentation time 24 h, fermentation temperature 30 ℃, and the inoculation ratio of L.plantarum to S.cerevisiae was 1:2 (3% compound fermentation strain). Ultrasonic pretreatment method significantly increased the content of γ-aminobutyric acid in rice bran ferment (P<0.05), microwave had no significant effect on the content of γ-aminobutyric acid(P>0.05), baking significantly reduced the content of γ-aminobutyric acid( P <0.05). Rice bran was treated with ultrasonic power 240 W for 24 h, the content of γ-aminobutyric acid in rice bran ferment was 2.61 g/L, which was 1.85 times than that of untreated rice. This article preliminary discusses the effect of different pretreatment methods on the quality of rice bran enzyme in order to provide a new idea for the subsequent preparation of rice bran ferment.