• Korean Journal of Food Science and Technology
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• v.37 no.5
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• pp.812-815
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• 2005

Effects of poly-${\gamma}$-glutamate (PGA) on antioxidative characteristics of amino-carbonyl reaction products of glucose were investigated. Rapid browning reaction was observed under heat and alkaline condition (pH 8.2). Browning products were separated by Sephadex G-50, and brown color intensity and electron-donating ability of DPPH (2,2-diphenyl-1-picrylhydrazyl) of each fraction were measured. Fraction-7 (F-7) and -20 (F-20) showed high DPPH scavenging values. UV-VIS absorption spectrum of F-20 was similar to melanoidin peak, and F-7 showed maximum absorption peak at 270 nm. Molecular weight of F-7 was over 35 kDa as determined by SDS-PAGE. Although F-20 could not be measured on SDS-PAGE, its size was smaller than F-7.

• Preventive Nutrition and Food Science
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• v.13 no.4
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• pp.354-361
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• 2008

A novel bacterium isolated from Cheonggukjang was identified as a glutamate-dependent Bacillus subtilis HA with 98.3% similarity to Bacillus subtilis Z99104. Optimization of poly-$\gamma$-glutamic acid ($\gamma$-PGA) production by modulating fermentation factors including carbon sources, nitrogen sources, inorganic salts and fermentation time was investigated. Optimum culture broth for $\gamma$-PGA production consisted of 3% glutamate, 3% glucose and various salts, resulting in the PGA production of 22.5 g/L by shaking culture for 72 hr at $37^{\circ}C$. Average molecular weight of $\gamma$-PGA was determined to be 1,220 kDa through MALLS analysis. The $\gamma$-PGA solution showed a typical pseudoplastic flow behavior, and a great decrease in consistency below pH 6.0 regardless of the same molecular weight of $\gamma$-PGA. The molecular weights of isolated $\gamma$-PGA were drastically decreased by heat treatment in various acidic conditions, resulting in different hydrolysis of $\gamma$-PGA. The consistency of $\gamma$-PGA solution was greatly decreased with increase heating time in acidic conditions.

• Journal of Microbiology and Biotechnology
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• v.23 no.6
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• pp.785-793
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• 2013

We studied the effects of 2 different dosages of high-molecular-weight poly-${\gamma}$-glutamic acid (hm ${\gamma}$-PGA) derived from Bacillus subtilis chungkookjang on lipid metabolism in a high-fructose diet-induced hypertriglyceridemic animal model. For 4 weeks, rats were fed either AIN-93 diet (normal control, NC; n = 10) or modified AIN-93 diet in which cornstarch was substituted with 63% fructose (n = 30) to induce hypertriglyceridemia. After 4 weeks, the hypertriglyceridemic rats were treated with daily oral doses of 0 mg (hypertriglyceridemic control, HC), 2.5 mg (hypertriglyceridemic, low hm ${\gamma}$-PGA, HL), or 5 $mg{\cdot}kg{\cdot}bw^{-1}{\cdot}d^{-1}$ (hypertriglyceridemic, high hm ${\gamma}$-PGA, HH) hm ${\gamma}$-PGA for 4 weeks. The HL and HH groups exhibited significantly lower levels of serum triglyceride, total cholesterol, LDL cholesterol, and free fatty acids than the HC group. The administration of hm ${\gamma}$-PGA reduced serum ALT and AST levels. The activities of lipogenic enzymes such as hepatic malic enzyme and glucose-6-phosphate dehydrogenase as well as glucose-6-phosphate dehydrogenase mRNA expression were significantly decreased by hm ${\gamma}$-PGA administration (p < 0.05). These results indicate that hm ${\gamma}$-PGA has an anti-hypertriglyceridemic effect in high-fructose diet-induced hypertriglyceridemic rats.

• Food Science and Preservation
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• v.31 no.1
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• pp.138-148
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• 2024

The production of poly-γ-glutamic acid (γ-PGA) and γ-aminobutyric acid (GABA) was optimized by serial fermentation of Dendropanax morbiferus extract (DME) using Bacillus subtilis HA and Lactobacillus plantarum KS2020. The 1st alkaline fermentation was performed on 60% DME including 2% glucose and 10% monosodium ʟ-glutamate (MSG) as a precursor. The 1^st fermented DME had 57 mg% tyrosine. Consequently, the 2^nd lactic acid fermentation for 5 days increased the tyrosine content of 106 mg%. The mucilage containing γ-PGA showed a high content of 3.50% on the first day of alkaline fermentation and then increased to 4.10% after 2 days. The precursor (MSG) remaining in the 1^st fermented DME was efficiently converted to GABA by the 2^nd lactic acid fermentation in the presence of 5% skim milk, 1.5% glucose and 0.5% yeast extract, resulting in the production of 18.29 mg/mL GABA. The viable cells of lactic acid bacteria increased and indicated 9.49 log CFU/mL on the fermentation for 5 days, and the acidity of co-fermented DME indicated the highest value of 1.55%. Conclusively, the serial fermented DME has multi-functional ingredients containing γ-PGA, GABA, peptides and probiotics.

• Korean Journal of Food Science and Technology
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• v.50 no.6
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• pp.572-580
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• 2018

Biologically active substances including gamma-aminobutryric acid (GABA) were added into whey by co fermentation using Bacillus subtilis HA and Lactobacillus plantarum EJ2014. The first fermentation using B. subtilis HA with 5% monosodium glutamate (MSG) and 2% glucose enhanced the production of poly-${\gamma}$-glutamic acid (PGA), resulting in higher consistency of $4.09Pas^n$ as well as whey protein peptides. After the second fermentation using L. plantarum EJ2014, the remaining MSG (3.40%) as a precursor was completely converted to 2.21% GABA. Furthermore, the lactose content in whey decreased from 6.73 to 3.68% after co-fermentation, and the tyrosine content increased from 20.47 to 38.24%. Peptides derived of whey proteins were confirmed by SDS-PAGE. Viable cell counts of B. subtilis and L. plantarum were 5.83 log CFU/mL and 9.20 log CFU/mL, respectively. Thus, co-fermentation of whey could produce the novel food ingredient fortified with biologically active compounds including GABA, ${\gamma}$-PGA, peptides, and probiotics.