The conditions to produce γ-aminobutyric acid by utilizing rice bran and lactic acid bacteria

• Main Authors: Shu-Hao Chen, 陳叔豪
• Other Authors: Tze-Kuei Chiou
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/54776573526411346729

碩士 === 國立臺灣海洋大學 === 食品科學系 === 101 === This study investigated the condition to produce γ-aminobutyric acid (GABA) by utilizing rice bran and lactic acid bacteria. Rice bran contains the active glutamate decarboxylase (GAD) which is a useful enzyme whose main function is to catalyze the irreversible α-decarboxylation of L-glutamate to produce GABA. The amount of lactic acid bacteria could provide more glutamate from the hydrolysis of rice bran and also existed the GAD. For this reason, we compared the function of the productivity of GABA on the different conditions of rice bran and lactic acid bacteria. Rice bran incubated with different pH value, it contained the highest quantity of GABA especially when using the pH 5.6 and pH 5.8 (1.78-1.79 mM). It found the GABA contained highest quantity was under water medium and no significantly with other pH value buffer when adding the selected lactic acid bacteria (LAB-A, -F, -J and -M) and nutrient source (5% skim milk powder and 1% glucose). Then we chose water as incubated medium, the four groups productions were between 5.59-10.69 mM. It was higher than without added nutrient source group 2.2-4.9 times. Rice bran and selected lactic acid bacteria in water medium with different concentrations of glucose to be the carbon source, and yeast extract to be the nitrogen source at 40oC for 48 hours, the results indicated the highest GABA content was 1% glucose group and 8% yeast extract group, the four groups productions were between 39.85-91.80 mM (411-947 mg/100 mL). It contents higher than without rice bran group 3.73-15.33 times. The results revealed the rice bran is efficient on the accumulation of GABA. In this reaction system, the GABA content no differs significantly while extra adding monosodium L-glutamate (MSG). The optimal time and temperature for LAB-A, -J and -M groups were at 40oC for 36 hours, and LAB-F group was at 35oC for 24 hours. The GABA content increased significantly when adding the rice bran to 2 times, it was higher than 1.1 times, but rose up to 4 and 6 times, the GABA content increased gradually slow. According to the situation, we suggested there were too many rice bran to disturb the liquidity and caused it reacted slowly.