Use of Hypoxia Combined with Acid Stress to Enrich GABA in Adzuki /Mung Beans, and Optimization of GABA-rich Sprouted Bean/Rice Mixture Processing Conditions

In order to study the effect of hypoxia combined with acid stress on GABA enrichment in adzuki bean and mung bean, germination time, germination temperature, hypoxia time and L-glutamic acid concentration were investigated by single factor. Based on the stress conditions identified for high GABA sprouted beans, GABA-enriched adzuki and mung beans were mixed with rice, and D-mixture design was used to optimize processing conditions for these sprouted bean/rice mixtures. Results showed that hypoxia combined with acid stress promoted GABA enrichment in adzuki and mung beans. In sprouted adzuki beans, GABA reached levels as high as 158.32±3.24 mg/100 g under the germination time of 48 h, germination temperature of 40 ℃, 15 h exposure to hypoxia, and L-glutamic acid concentration of 2.5 mg/mL. Mung bean stress conditions were: Germination time of 24 h, germination temperature of 35 ℃, 15 h exposure to hypoxia, and L-glutamic acid concentration of 2.5 mg/mL, the content of GABA was 141.57±4.35 mg/100 g. The sprouted beans and rice formulation was optimized by D-mixture design as follows: Rice 76%, sprouted mung beans 11%, and sprouted adzuki beans 13%. Under this composition, the GABA content of sprouted bean/rice mixture was 23.73±1.03 mg/100 g, and the average sensory score was 88.76±2.47. The taste, color, and aroma of the sprouted bean/rice mixture fell within acceptable ranges, and the active ingredient GABA was enriched, enhancing the nutritional and functional properties of sprouted beans/rice. This study provided a theoretical reference for the further development of rice/grain mixtures.