Study On Γ-Aminobutyric Acid Accumulation And Freeze-Drying Technology Of Germinated Soybean (Glycine Max L. Merr.)

The cultivar for γ-amino butyric acid (GABA) accumulation was selected from four soybean cultivars. The culture conditions and culture solution composition for GABA accumulation in germinated soybean was optimized. In the optimal culture conditions and medium, the changes of main physiological and biochemical index, GABA content, enzyme activity and precursor content during germination were determined. One lyophilized soybean soup rich in GABA was designed and developed. The main results were the following:1. After 4 days germination, the germination percentage, sprout length and respiratory rate of soybean cultivar YH-NJ was higher than that of the others. The increment of soluble protein, free amino acid and protease activity in YH-NJ sprouts were higher than that of the others. The GABA content and its amount increased in YH-NJ sprouts were the highest. So cultivar YH-NJ was selected for GABA accumulation for further experiments. Using orthogonal design method, the optimal culture conditions for GABA accumulation in 4-day germinated YH-NJ sprouts were germinated in a culture solution of pH 5.0 for another 48 h under hypoxia stress at 30℃. Under these conditions, the content of GABA was 1.97 mg/g DW, which was 1.56 times of the control.2. The optimal compositions of culture solution for GABA accumulation were NaCl of 42.49 mmol/L, VB6 of 62.6μmol/L and CaCl2 of 6.21 mmol/L. In this medium, GABA content in soybean sprouts was 2.77 mg/g DW. The changes of physiological and biochemical parameters of soybean germinated under hypoxia indicated that the growth and the respiration was inhibited, the consumption of crude protein increased, At the same time, the content of free amino acid increased, the activity of GAD and DAO were promoted, leading to the accumulation of GABA.3. The formula and product of lyophilized soybean soup containing germinated soybean rich in GABA were designed and developed. The results showed that the optimal blanching conditions were blanched at 100℃ for 30 s with the Ca2+ concentration of 0.05%. The lyophilized soybean soup was combined with soybean sprouts, eggs, carrots, mushrooms and vegetables in a certain percentage, optimized flavor and dried-freezed. The product has a nice mouth-feel, good reconstituability and mobility. This soup was rich in GABA and suitable for consumers’ health.