• 한국식품조리과학회지
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• 제29권6호
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• pp.671-677
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• 2013

The objective of this study was to examine the levels of free amino acids and identify the correlation between ${\gamma}$-aminobutyric acid (GABA)and L-glutamic acid contents in Kimchi during fermentation. During 2 weeks of fermentation, the acidity of Kinchi increased, i.e., the pH level decreased from 5.24 to 4.40. The content of amino acids determined using HPLC differed significantly (p < 0.05) during 7 weeks of fermentation. Over the 7 weeks of fermentation, the content of most free amino acids increased in the order L-valine > L-glutamic acid > L-glycine, except L-methionine decreased. Initially, the GABA content was found to be $72.43{\mu}M/100g$ fresh weight (fw), and it increased to $229.06{\mu}M/100g$ fw after 7 weeks. This rapid increase in the GABA content in the initial stage is considered to be due to L-glutamic acid. However, during the period of 0~7 weeks, no correlations were found between the L-glutamic acid and GABA contents.

• Food Science and Biotechnology
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• 제17권5호
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• pp.940-946
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• 2008

In the development of a nutrient enhanced functional food, kimchi was produced by using high $\gamma$-aminobutyric acid (GABA) producing lactic acid bacterium as a starter strain. The strain isolated from kimchi was identified by using an API kit and named Lactobacillus sp. OPK 2-59. Kimchi was produced by 3 methods 1) monosodium glutamate (MSG) added (M group); 2) starter added (S group); 3) MSG+starter added (M&S group). The produced kimchi was fermented for 24 hr in an incubator at a temperature of $15^{\circ}C$ and stored at $0-1^{\circ}C$ to examine its characteristics. The M&S group exhibited a sharper increase in acidity and a steeper fall in pH as well as a higher number of lactobacilli. The M&S group kimchi had 18 mg/100 g (fresh weight, f.w.) of GABA, whereas the M and S group each had 6 mg/100 g (f.w.) GABA. According to functional evaluation, the M&S group kimchi, which has higher GABA, was not significantly different in taste, color, texture, or smell, but the M&S group was generally superior. In summary, using Lactobacillus sp. OPK 2-59 and MSG, a high quality kimchi with increased GABA content can be produced as a functional food.

• Journal of Microbiology and Biotechnology
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• 제17권1호
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• pp.104-109
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• 2007

Lactic acid bacteria that accumulated ${\gamma}-aminobutyric$ acid (GABA) in culture medium were screened to identify strains with high GAB A-producing ability. One strain, MS, which was isolated from kimchi, showed the highest GABA-producing ability among the screened strains. MS was identified as Lactobacillus buchneri based on Gram-staining, metabolic characteristics, and 16S rDNA sequence determination, Optimum culture conditions for GABA production were determined: MRS broth containing 5% MSG, 1% NaCl, and 1% glucose, at an initial pH of 5.0, the incubation temperature at $30^{\circ}C$ for 36 h. Under these conditions, MS produced GABA at a concentration of 251 mM with a 94% GABA conversion rate. Moreover, culture extracts of Lb. buchneri MS partially or completely protected neuronal cells against neurotoxicantinduced cell death.

• 한국식품영양과학회지
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• 제45권6호
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• pp.923-928
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• 2016

김치용 결구배추를 겉잎(L1), 중잎(L2), 속잎(L3)으로 세 등분하여 부위별로 일반성분을 포함한 이화학적인 성분을 측정하여 비교하였다. 조단백질 및 조지방 함량은 겉잎(L1)이 높았고, 조회분 및 탄수화물 함량은 속잎(L3)이 높았다(P<0.05). 열량은 24.5~26.5 kcal/100 g이었고 부위별로 유의적인 차이가 없었으며, 총식이섬유는 겉잎(L1)이 가장 높았다(P<0.05). 유리당은 fructose, glucose, sucrose가 확인되었으며, 속잎(L3)에서 fructose 및 glucose 함량이 높았다(P<0.05). 유기산은 citric acid, malic acid, succinic acid가 검출되었으며, citric acid와 malic acid 함량은 속잎(L3)이 높았고 succinic acid는 겉잎(L1)이 높았다(P<0.05). 총유리 아미노산의 30% 이상을 차지하는 glutamic acid 함량은 속잎(L3)에서 높았으며, ${\gamma}-aminobutyric$ acid의 함량은 겉잎(L1)이 가장 높았다(P<0.05). 결구배추 잎의 주요 미네랄 성분은 K, Na, Ca, Mg이며, 이 중 K의 함량이 가장 높았다. 총미네랄 함량은 겉잎(L1)이 가장 높았다(P<0.05). 결구배추 잎은 부위에 따라 이화학적 성분 조성이 다른 특성을 가지므로 신선편의 식재료로서 활용성이 더욱 증대될 수 있을 것으로 생각한다.

• 한국축산식품학회지
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• 제37권6호
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• pp.804-812
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• 2017

This study was carried out to determine the physicochemical, microbiological, and quality characteristics of a new type of fermented sausage manufactured by incorporating Baechu-kimchi powder and gamma-aminobutyric acid (GABA)-producing lactic acid bacteria (LAB). The LAB count was at the maximum level by day nine of ripening in inoculated sausages, accompanied by a rapid decrease in the pH. The addition of kimchi powder decreased the lightness ($L^*$) and increased the redness ($a^*$) and, yellowness ($b^*$) values, while also significantly increasing the hardness and chewiness of the sausage (p<0.05). Moreover, although the thiobarbituric acid reactive substances values increased in all samples during the study period, this increase was lower in the kimchi-treated samples, indicating a reduction in lipid oxidation. Overall, our results show that the addition of Baechu-kimchi powder to sausages reduced the off-flavor properties and improved the taste profile of the fermented sausage in sensory evaluations. The GABA content of all fermented sausages increased from 17.42-25.14 mg/kg on the third day of fermentation to 60.95-61.47 mg/kg on the thirtieth day. These results demonstrate that Baechu-kimchi powder and GABA-producing LAB could be functional materials in fermented sausage to improve quality characteristics.

• Journal of Microbiology and Biotechnology
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• 제29권11호
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• pp.1745-1748
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• 2019

Gamma-aminobutyric acid (GABA) plays important roles in host physiology. However, the effects of GABA are greatly restricted due to its low bioavailability in the human body. Here, a high acid-tolerance GABA-producing strain, Lactobacillus brevis Bmb5, was isolated from kimchi. Bmb5 converted glutamate to GABA (7.23 ± 0.68 ㎍/μl) at a rate of 72.3%. The expression of gadB gene, encoding the enzyme involved in the decarboxylation of glutamate to GABA, was decreased upon incubation. Our findings indicate GABA production in Bmb5 is not directly correlated with gadB gene expression, providing new insight into the mechanisms underlying GABA production in Lactobacillus.

• 미생물학회지
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• 제47권4호
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• pp.316-322
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• 2011

김치로부터 분리한 유산균 Lactobacillus sakei OPK2-59는 ${\gamma}$-aminobutyric acid (GABA) 생성능력과 glutamate decarboxylase(GAD) 활성을 보유하고 있음이 확인되었다. Lactobacillus sakei OPK2-59를 59.13 mM과 177.40 mM monosodium glutamate (MSG)가 함유된 MRS 배지에서 배양하면 균주의 성장을 위한 최적 온도범위와 pH는 각각 $25-37^{\circ}C$와 6.5였다. 59.13 mM과 177.40 mM MSG 함유 MRS 배지에서 배양온도 $25^{\circ}C$ 조건에서, 48시간 배양하였을 경우 MSG의 GABA 전환율은 각각 99.58%와 31.00%였다. 또한 Lactobacillus sakei OPK2-59 세포추출액을 이용하여 MSG를 GABA로 전환할 수 있었으며, 추출물에 의한 GABA 전환율은 $30^{\circ}C$, pH 5 조건에서 78.51%로 가장 높았다. 세포추출액에 의한 MSG의 GABA 전환에 미치는 무기염의 영향을 조사한 결과 $CaCl_2$, $FeCl_3$, $MgCl_2$를 첨가한 반응액에서 염을 넣지 않고 반응한 control보다 GABA 전환율이 2-3배 증진되는 것으로 조사되었다. 이러한 결과들은 김치 유산균 Lactobacillus sakei OPK2-59의 GABA 생성능은 유산균 세포 내에 존재하는 GAD에 의한 것이며, GAD에 의한 GABA 전환율은 무기염에 의하여 증진될 수 있음을 제안해 주는 것이다.

• Journal of Microbiology and Biotechnology
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• 제27권3호
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• pp.450-459
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• 2017

This study evaluated the effects of culture conditions, including carbon and nitrogen sources, L-monosodium glutamate (MSG), and initial pH, on gamma-aminobutyric acid (GABA) production by Lactobacillus brevis HYE1 isolated from kimchi, a Korean traditional fermented food. L. brevis HYE1 was screened by the production analysis of GABA and genetic analysis of the glutamate decarboxylase gene, resulting in 14.64 mM GABA after 48 h of cultivation in MRS medium containing 1% (w/v) MSG. In order to increase GABA production by L. brevis HYE1, the effects of carbon and nitrogen sources on GABA production were preliminarily investigated via one-factor-at-a-time optimization strategy. As the results, 2% maltose and 3% tryptone were determined to produce 17.93 mM GABA in modified MRS medium with 1% (w/v) MSG. In addition, the optimal MSG concentration and initial pH were determined to be 1% and 5.0, respectively, resulting in production of 18.97 mM GABA. Thereafter, response surface methodology (RSM) was applied to determine the optimal conditions of the above four factors. The results indicate that pH was the most significant factor for GABA production. The optimal culture conditions for maximum GABA production were also determined to be 2.14% (w/v) maltose, 4.01% (w/v) tryptone, 2.38% (w/v) MSG, and an initial pH of 4.74. In these conditions, GABA production by L. brevis HYE1 was predicted to be 21.44 mM using the RSM model. The experiment was performed under these optimized conditions, resulting in GABA production of 18.76 mM. These results show that the predicted and experimental values of GABA production are in good agreement.

• Preventive Nutrition and Food Science
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• 제13권3호
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• pp.219-224
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• 2008

In this study, we investigated changes in some physico-chemical and biochemical properties of Kimchi during fermentation and storage. After fermenting Kimchi at $15^{\circ}C$ for 23, 36, 40, 44, and 60 hrs during the first week, we stored it at $-1^{\circ}C$ in a Kimchi refrigerator until the end of 8th week. The pH of samples fermented for 36 hr, 40 hr, 44 hr and 60 hr sharply decreased during the first seven days and then slowly decreased. Acidities of samples fermented for 36 hr, 40 hr and 44 hr sharply increased for the first seven days. According to measured changes of lactic acid bacteria number, samples fermented for 60 hr revealed the largest augmentation in the number of lactobacilli for the first seven days. The $\gamma$-aminobutyric acid (GABA) content of the sample fermented for 40 hr was the most superior, with an early increase and maintenance of GABA content, which maintained a maximum 20 mg per 100 g of Kimchi sample on the seventh, fourteenth, and twenty eighth days. These results suggest that relatively enhanced levels of GABA in Kimchi samples can be produced and maintained by controlling the fermentation and storage processes, as with the 40 hr fermented sample conditions.

• Journal of Microbiology and Biotechnology
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• 제28권4호
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• pp.534-541
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• 2018

Kimchi (a traditional Korean fermented vegetable) was prepared with a starter, Lactobacillus zymae GU240 producing ${\gamma}$-aminobutyric acid (GABA), and one precursor of GABA (glutamic acid, glutamic acid monosodium salt (MSG), or kelp extract). L. zymae GU240, an isolate from kimchi, can grow at 7% NaCl and low temperature. Five different kimchi samples were fermented for 20 weeks at $-1^{\circ}C$. Kimchi with starter alone could not produce GABA. The GABA content was highest in kimchi with co-inoculation of the starter and MSG (1% (w/w)). Kimchi co-inoculated with the starter and kelp extract powder (3% (w/w)) had the second highest GABA content. Addition of glutamic acid powder (1% (w/w)) caused a reduction in the pH level of kimchi and growth inhibition of lactic acid bacteria and yeasts. Kimchi samples with MSG or kelp extract showed improvement of sensory evaluation scores. The results demonstrate the possibility to produce kimchi with improved functionality and taste by using L. zymae GU240 as a starter along with a suitable precursor such as MSG or kelp extract.