Stability of Anti-Yeast Activities and Inhibitory Effects of Defatted Green Tea Seed Extracts on Yeast Film Formation
2017
Yang, E.J., Jeonnam Bioindustry Foundation, Naju, Republic of Korea | Seo, Y.S., Jeonnam Bioindustry Foundation, Naju, Republic of Korea
Water and 75% ethanol extracts were prepared from defatted green tea seeds and evaluated for their anti-yeast activities. The antimicrobial activities of defatted green tea seed extracts (DGTSEs) were tested against food-spoilage bacteria, yeasts, and molds. DGTSEs exhibited antimicrobial activities with minimum inhibitory concentrations of 39∼1,250 microgram/mL against three bacteria, two molds, and all tested yeast strains. Ethanol extract showed higher antimicrobial activity than water extract. The stability of anti-yeast activities of DGTSEs was examined under different conditions of temperature, pH, and NaCl concentrations. The anti-yeast activities of DGTSEs were stable at pH 3~9, 0~20% NaCl, and 100℃ for 30 min. However, anti-yeast activities of DGTSEs decreased upon heating at 70℃ for 24 h or 121℃ for 15 min. DGTSEs were applied to food models to determine their inhibitory effects on yeast film formation. Water and 75% ethanol extracts were effective in preventing yeast film formation at concentrations more than 156 and 39 microgram/mL in soy sauce, 156 and 78 microgram/mL in pickle sauce, and 78 and 39 μg/mL in kimchi, respectively.
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