Study On The Enrichment Conditions Of γ-aminobutyric Acid Content In Germinated Brown Rice Or Soybean And Compound Grain Beverage

Glutamic acid decarboxylase catalysis glutamate to synthesis GABA which is a kind of non-protein amino acid.As a kind of important inhibitory neurotransmitters,it plays a very important role in life.Therefore,in this paper,brown rice and soybean were treated through germination to improve GABA content.The method of RP-HPLC wich was used to determinate GABA content in germinated brown rice were studied.The results showed that this method was precision(relative standard deviation＜1.1%) and have good stability(RSD 1.08%).The soaking conditions on water absorption,as well as the different germination conditions on GABA content were studied.The culture fluid was added pyridoxal phosphate (PLP) as a coenzyme of glutamic acid decarboxylase,sodium glutamate(MSG) as a substrate to measure their impact on GABA content;Response surface method was used to optimize the process,arrived at the optimum technological conditions of germinated brown rice as follows: soaking temperature at 30℃,soaking time at 12h,germination time at 25h,germination temperature at 31℃,MSG at 2.0mg/mL,PLP/MSG at 2.0mmol/mol,the GABA content reached to 48.92mg/100g.dry weight;the optimum technological conditions of germinated soybean as follows:soaking temperature at 25℃,soaking time at 16h,germination time at 50h,germination temperature at 30℃,MSG concentration at 2.6mg/mL PLP/MSG at 1.6mmol/mol,the GABA content reached to 220.60mg/100g.dry weight.The technological conditions of compound beverage were studied,along with the utilization of raw materials and the DE value of supernatant as indexes.The optimum hydrolysis process was obtained by orthogonal test as follows:the ratio of material to water at 1:8,the temperature of enzymatic hydrolysis at 80℃,the time of enzymatic hydrolysis at 30min,the amounts of thermo-stable amylase at 5U/g;through sensory evaluation to determine the best formula:nob-dairy creamer 0.8%,white sugar 5%.The effects of stabilizer for the stability of the compound beverage were studied.The best compatibility proportion of emulsifiers and thickeners is:sodium caseinate 0.15%,sucrose fatty acid ester 0.15%,sodium alginate 0.05%,sodium carboxymethyl fiber 0.15%.Through different conditions of sterilization and homogenization to determine the best parameters: homogeneous temperature at 65℃,frist homogeneous stress at 40MPa,second homogeneous stress at 30MPa;sterilization temperature at 115℃,sterilization time at 15min;under these parameters,GABA content in the compound beverage reaches to 9.48mg/100mL,microbial quantity was in line with national standards.