Germinated brown rice and its bio-functional compounds.

GABA has attracted great attention over the last several decades due to its ubiquity in life. It is an important molecule naturally present in considerable amounts in many feed and food matrices of...

https://www.tandfonline.com/doi/pdf/10.1080/23311932.2018.1534323

GABA, a non-protein amino acid ubiquitous in food matrices

In this study we investigated the effect of temperature on the two-stage fermentation of Makgeolli using uncooked germinated black rice. The fermentation processes were conducted at 15℃ for three weeks and 25℃ for 7 days. The pH of Makgeolli at 25℃ increased from pH3.0 to pH 4.2, which was consistent with that at 15℃. In contrast total acidity of Makgeolli at 15℃ was about half of that at 25℃ (0.36% and 0.59%, respectively). By the 7 days-fermentation at 25℃, 11% of alcohol was produced, whereas three weeks were required for the same alcohol production at 15℃. In the case of sugar contents, the amounts of total glucose-equivalent reducing sugars and glucose increased at the end of the fermentation at 25℃ up to 2.25 mg/mL and 3.4 mM, respectively, whereas those at 15℃ were maintained at very low levels (0.18 mg/mL and 0.1 mM, respectively). Such limited supplement of sugars at 15℃ seemed to affect metabolism of yeast, resulting in different composition of organic acid. At 25℃, citric acid that was 73.4 ppm at the initial fermentation was consumed completely, whereas 20 ppm of citiric acid was remained at 15℃. In addition, acetic acid and lactic acid in Makgealli at 15℃ were 53% and 14% of those at 25℃.

무증자 발아흑미를 이용한 막걸리 제조 시 온도가 미치는 영향

Effects of soaking and sprouting on bioactive compounds of black and red pigmented rice cultivars

To isolate GABA-producing microorganisms, 1,500 strains were isolated from different Chungkookjang samples and screened. From these strains, 20 were selected for further analyses based on a protease and slime-producing activity test. The MC 31 strain showed the highest GABA concentration in Chungkookjang and was used in this study. MC 31 was identified as Bacillus subtilis by an API 50CHB kit and 16S rDNA sequences analysis and named as B. subtilis MC 31. B. subtilis MC 31 showed exponential growth up to 12 hours at in LB broth, and it reached a stationary phase after 24 to 36 hours of incubation. B. subtilis MC 31 showed maximum GABA content at 72 hours after incubation at .

https://www.koreascience.or.kr:443/article/JAKO201306735657653.pdf

Isolation and Identification of GABA-producing Microorganism from Chungkookjang

The level of -aminobutyric acid (GABA) in pigmented rice was quantitatively and qualitatively determined by high pressure liquid chromatography/fluorescence detection (HPLC/FLD). In this study, the recovery rate and limit of detection (LOD) of GABA were 122.42.4% and 0.23 , respectively. The geminating pigmented rice samples, which were harvested in Paju, Korea, were soaked in water at for 20 hr. After soaking, the samples were germinated at for about 24 hr. GABA content was highest (293.0 ) in the germinated red rice. Furthermore, GABA levels in the germinated rice increased significantly by up to 11.1 and 24.7-fold as compared to non-germinated rice and milled rice, respectively. The GABA concentrations of non-germinated rice, with the exception of red rice, were significantly higher than those of milled rice by 7.6-20.6-fold.

Sang-Hwa Lee

Papers

Anaylsis of ${\gamma}$-aminobutyric Acid (GABA) Content in Germinated Pigmented Rice