• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.1
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• pp.176-181
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• 2004

Gluconacetobacter hansenii TF-2, an isolate from black tea fungus, was statically cultivated to ferment cellulose gel from citrus juice. The juice prepared by press filtering of peeled citrus fruit contained 135.5 mg of total sugar/mL, 1.23% of total acid, and average pH of the juice was 3.98. The bacterium produced cellulose gel optimally on the surface of culture broth containing 17% of citrus juice and 10$^{\circ}$Brix of total sugar. The optimum temperature was 3$0^{\circ}C$ for producing acetic acid and gel formation. The bacterium could not produce acetic acid on gel formation at 4$0^{\circ}C$. The optimum pH was 3.0∼4.0 but was not significantly different between pH 3.0∼4.0. The cultivation for 18 days under optimal conditions produced gel as 14.2$\pm$0.6 mm of thickness and acids equivalent to 1.90$\pm$0.22% of acetic acid. The pH of culture broth was stabilized at 2.6∼2.8 during the cultivation. Remaining sugar content was 27.1$\pm$4.2 mg/mL of total sugar and 6.9 mg/mL of reducing sugar. The gel productivity was 137.8$\pm$9.7 g/L.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.10
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• pp.1341-1350
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• 2007

This study was designed to ultimately develop a highly efficient mass production technology of bacterial cellulose isolated from the citrus gel fermented by G. hansenii TL-2C. Pilot equipment made with FRP vessel length (665 mm) ${\times}$ width (375 mm) ${\times}$ height (210 mm) was developed for mass production of the citrus gel. To develop the optimal conditions for mass production of citrus gel, comprised of citrus juice (6,000 mL) diluted 100 times, containing 5% seed bacteria, 10% sucrose, and 1% ethanol, citrus juice was fermented at $30^{\circ}C$ for 14 days, and gel productivity in pilot system was examined. BC was isolated and purified from the citrus gel, and their chemical composition and physicochemical properties were investigated.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.8
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• pp.1037-1043
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• 2008

In this experiment, citrus juice was fermented by Gluconacetobacter hansenii TF-2, an isolate from tea fungus to develop a new type of acidic beverage. The juice broth is made by fermenting of $11{\sim}17%$ (v/v) juice and sweetened with sucrose (initial sucrose $10^{\circ}Brix$). The fermentation by G. hansenii TF-2 was initiated by adding 5% (w/v) of seed gel (pellicle, tea fungus) which was previously cultured in the same medium (fresh juice broth) and the fermentation was carried out in a dark incubator at $28{\sim}30^{\circ}C$ for about 15 days. During the fermentation a pellicle grew on the surface of the fermenting fluid and acids were produced. Fermented fluid (beverage) was centrifuged at 7,000 rpm for 15 min for further analyses. The highest amount of the other metabolites including organic acids were observed in 5 to 10 days. Major acids were acetic acid (fermented citrus beverage, CB). After 15 days of fermentation, organic acid content such as acetic acid in fermented beverage was measured to be $183.5{\sim}186.6\;ppm$. Free sugars content in CB were 56.8%, 35.1%, 40.7% and 63.2% of unfermented sucrose, glucose, fructose and sorbitol, respectively. When the growth rate of inhibitory effect of the fermented beverage was measured by using several species of food-related bacteria, the beverage fermented with CB exhibited the strongest inhibition against gram-negative (E. coli and Sal. Typhimurium). Its inhibition rate was between $71.9{\sim}94.0%$ at CB. Fermented beverage has shown effectiveness for antimicrobial activity against some species of food-related bacteria.

• Food Science and Preservation
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• v.18 no.1
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• pp.46-52
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• 2011

Wild grape juice was fermented by Gluconacetobacter hansenii TF-2 isolated from tea fungus, to develop a new acidic beverage (fermented wild grape beverage, WGB). Broth was prepared by fermentation of 11~17% (v/v) juice, and sweetened with sucrose (initial sucrose level: $10^{\circ}$ Brix). Fermentation was initiated by addition of 5% (w/v) seed gel (the pellicle of the tea fungus) which had been previously cultured in the same medium (freshjuice broth), and fermentation proceeded in the dark at $29{\pm}1^{\circ}C$ for about 15 days. The major acids produced were succinic acid, malic acid, and acetic acid. After 15 days of fermentation, the organic acid content (principally succinic acid) was 49.6 ppm in WGB 11 and 77.4 ppm in WGB 17. The free sugar content of WGB was 1063.6-1082.5 mg/mL, composed of unfermented fructose, glucose, and sucrose, in that order. The microbial inhibitory effects of the fermented beverage were most apparent when Gram-negative bacteria (Escherichia coli and Salmonella typhimurium) were tested; the inhibition rate was 34.46-88.00%. The new fermented beverage thus displays effective antimicrobial activity against some species of bacteria.