Effects of glutamic acid (Glu) and monosodium glutamate (MSG) on oxidative stability of oil-in-water (O/W) emulsions with different emulsifier charges during riboflavin (RF) photosensitization were evaluated by analyzing headspace oxygen content and conjugated dienes. Cetyltrimethylammonium bromide (CTAB), Tween 20, and sodium dodecyl sulfate (SDS) were used as cationic, neutral, and anionic emulsifiers, respectively. Glu acted as an antioxidant in CTAB- and Tween-20-stabilized O/W emulsions during RF sensitization, whereas Glu acted as prooxidants in SDS-stabilized O/W emulsions in the dark. However, adding MSG did not have a constant impact on the degree of oxidation in O/W emulsions irrespective of the emulsifier charge. In RF-photosensitized O/W emulsions, the emulsifier charge had a greater influence on antioxidant properties of Glu than on those of MSG.

글루탐산은 식물의 생장과 발달에 중요한 역할을 하는 필수 아미노산의 전구체이며, 저온 보호 물질로 이어지는 생합성 경로를 자극하여 저온 피해를 줄이는 생물자극제 중 하나이 다. 본 연구에서는 저온 스트레스 조건에서 글루탐산 엽면 처 리가 배추에 미치는 영향을 평가하였다. 글루탐산 2가지 엽면 시비 농도(0 및 10mg·L-1)와 3가지 주/야간 온도 수준(11/－1 °C extremely low, E; 16/4°C moderately low, M; 21/9°C optimal, O)을 결합하여 6개의 처리가 수행되었다. 글루탐산 의 엽면 처리는 정식 후 10일에 1회 살포하고, 글루탐산 처리 직후 온도 처리는 최대 4일 동안 실시하였다. 처리 4일 후, ABA, PA, DPA 및 ABA-GE 함량은 M 처리에서 Glu 0 처리 보다 Glu 10 처리에서 함량이 더 높았다. Glucose 함량은 E 및 Glu 10 처리에서 가장 높은 반면(52.1mg·100g-1 dry weight), fructose 함량은 O 및 Glu 0 처리에서 함량이 가장 높았다 (134.6mg·100g-1 dry weight). GLP, GBS, 4MGBS, GNBS 및 GNS 함량은 E 및 Glu 10 처리에서 모든 처리 중 가장 높았 다(0.72, 2.05, 1.67, 9.40 및 0.85μmol·g-1 dry weight). 처리 2일 후 E 및 Glu 10 처리의 PA와 DPA함량에서 급격한 변화 를 확인하였고, 몇몇 개별 glucosinolate 함량(GLP, GBS, 4MGBS, GNBS 및 GNS)은 저온과 글루탐산 처리에 따라 유 의적 차이를 확인할 수 있었다. 또한, fructose는 glucose 대신 fructan을 에너지원으로 사용하였기 때문에 처리 4일후 E와 M처리에서 O 처리에 비하여 유의적으로 낮은 함량을 보였다. 따라서, 저온과 글루탐산 엽면 처리에 따른 PA, DPA, glucose, fructose 및 개별 glucosinolate 물질들의 변이를 확 인하였지만, 저온과 글루탐산의 효과에 관한 명확한 상관관계를 평가할 수는 없었다. 배추과 작물은 호냉성 채소로서 저 온에 민감하게 반응하지 않고, 대부분 내한성을 가지고 있기 때문으로 판단된다.

Poly-γ-glutamic Acid(γ-PGA)를 다량 생산하는 균주를 우리나라의 전통발효식품인 청국장으로부터 Bacillus subtilis GS-2를 분리하였다. 이 균은 glutamic acid 의존형 균으로, 이 균에 의한 γ-PGA 생산 최적 조건을 검토한 바, 단순배 지(L-glutamic acid 2.0%, glucose 1.0%, NH₄Cl 0.5%, KH₂PO₄ 0.05%, MgSO₄, 7H₂O 0.01%, pH 7.0)로 진탕배양(220 rpm) 하였을 때, 배양시간 48시간, 최적온도 33℃, 그리고 초기 pH 6.5로 나타났다. 영양원으로 glutamic acid 3%, sucrose 3%, NH₄Cl 0.25%, KH₂PO₄ 0.15%, MgSO₄, 7H₂O 0.015%에서 γ-PGA 최대 생산량이 31.0 g/ℓ이었다. Key words: Chungkookjang, culture medium, poly(γ-glutamic acid), PGA, soybean paste

[Object] Gamma-Amino Butyric Acid (GABA), a four-carbon non protein amino acid, is widely distributed in nature and acts as the major suppressive neurotransmitter in the mammalian central nervous system. Recently, GABA has been reported to have several physiological functions such as antihypertensive, diuretic, relaxing and antidiabetic effects. Due to these unique biological functions, GABA has been used as functional ingredients for functional foods. Glutamic Acid Decarboxylase (GAD), which catalyzes decarboxylation of L-glutamic acid to GABA, has been purified from mammals, higher plants, and some microorganisms and their properties have already been reported. On the other hand, mushrooms are commonly appreciated as healthy food due to their nutritional properties, such as low calorie, rich in fiber, vitamin and mineral. L-Glutamic acid and GABA are also commonly distributed in edible mushrooms. The fact that mushrooms accumulate GABA suggests the existence of GAD. However, the enzyme property of mushroom GAD has not been reported. In the present study, we tried to evaluate the property of Flammulina veltipes GAD, and the purification and characterization of enzyme is also investigated. [Methods and Results] Mushroom (fruit-body of Flammulina veltipes) used in this study was purchased in local market. GAD activity was determined by formation of GABA from L-glutamic acid in the presence of pyridoxal-5’- phosphate (PLP). The activity of enzyme was determined semi-quantitatively by color intensity of GABA on TLC analysis. Fruit-body was crushed and then centrifuged to separate supernatant and precipitate. To investigate the location of GAD, both supernatant and precipitate were subjected to enzyme reaction after dialysis. The enzyme activity of precipitate is stronger than that of supernatant. The formation of GABA was observed between pH 4 and 6 and the maximum color intensity of GABA was observed at pH 6. However, GAD activity was lost after dialysis for overnight against buffer of pH 6-11. These results suggest that GAD from Flammulina veltipes is stable at pH 4-5 in spite of its optimum pH for GABA production is around 6.

Gamma-Amino Butyric Acid (GABA), a four-carbon non protein amino acid, is widely distributed in nature and acts as the major suppressive neurotransmitter in the mammalian central nervous system. Recently, GABA has been reported to have several physiological functions such as antihypertensive, diuretic, relaxing and antidiabetic effects. Due to these unique biological functions, GABA has been used as functional ingredients for functional foods. Glutamic Acid Decarboxylase (GAD), which catalyzes decarboxylation of L-glutamic acid to GABA, has been purified from mammals, higher plants, and some microorganisms and their properties have already been reported. On the other hand, mushrooms are commonly appreciated as healthy food due to their nutritional properties, such as low calorie, rich in fiber, vitamin and mineral. L-Glutamic acid and GABA are also commonly distributed in edible mushrooms. The fact that mushrooms accumulate GABA suggests the existence of GAD. However, the enzyme property of mushroom GAD has not been reported. In the present study, we tried to purify and characterize the property of Flammulina veltipes. [Methods and Results] Mushroom (fruit-body of Flammulina veltipes) used in this study was purchased in local market. GAD activity was determined by formation of GABA from L-glutamic acid in the presence of pyridoxal-5’š- phosphate (PLP). The GAD activity was determined by the formation of GABA from L-glutamic acid. Fruit- body was crushed and then centrifuged to separate supernatant and cell debris. To investigate the localization of GAD, both supernatant and precipitate were subjected to enzyme reaction after dialysis. The cell debris showed stronger GAD activity than that of supernatant. The formation of GABA was observed between pH 4 and 6 and the maximum GAD activity was observed at pH 6. However, GAD activity was lost after dialysis for overnight against buffer of pH 6-11. These results suggest that GAD from Flammulina veltipes is stable at pH 4-5 in spite of its optimum pH for GABA production is around 6.

현미(brown rice)를 이용하여 기능성 성분인 GABA의 고함량 발아조건을 효과적으로 활용한 최적조건을 설정하고자 조단백 함량과 GABA 함량을 분석하였다. 발아온도 에서 조단백 함량과 GABA 함량은 와 425.7 nmole/g으로 나타났으며 발아시간 72시간에서 조단백 함량과 GABA 함량이 와 637.0 nmole/g으로 나타났다. chitosan과 glutamic acid 100 ppm을 혼합한 처리구에서 발아시킨 현미의 조단백 함량