• Microbiology and Biotechnology Letters
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• v.43 no.4
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• pp.350-356
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• 2015

There have been several studies on role of hormesis with light stimulation, however, the influence of light on fermentation is still poorly understood. In this study the relationship between LED (light emitting diode) hormesis and ethanol fermentation for Muscat bailey A wine was investigated. Two LEDs, one blue ($453{\pm}4nm$) and one green ($522{\pm}3nm$), were used. Both LED groups showed an inhibited production of lactic acid. The blue LED stimulated the growth of the yeast in early stage of the fermentation. Polyphenolic compounds and their antioxidant abilities were significantly increased by the green LED. These results demonstrate that LED irradiation must bring about hormesis and affect the growth rate of yeast in the early stage of the fermentation, and the contents of phytochemicals during fermentation. These findings indicate the possible application of LED hormesis for the wine fermentation. Further studies are needed to understand how LED irradiation induces hormesis effects during the fermentation process.

• Food Science and Preservation
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• v.21 no.6
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• pp.851-858
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• 2014

Muscat Bailey A (MBA) wine was fermented using the indigenous Korean Saccahromyces cerevisiae strains S13 and D8, and the fermentation characteristics were compared with those of S. cerevisiae W-3, an industrial wine yeast. The strains S13 and D8 showed delayed alcohol fermentation compared with the W-3 strain, but the final alcohol contents of the S13 and D8 wines after fermentation were similar to those of the W-3 wine. The S13 wine showed significantly lower malic-acid content than the W-3 wine, but the D8 wine showed a similar level. Both the wines fermented using the S13 and D8 strains showed significantly lower acetaldehyde, methanol, and fusel oil contents, including n-propanol, iso-butyl alcohol, and iso-amyl alcohol, compared to the W-3 wine. Especially, the methanol content was 98.6 mg/L in the S13 wine and 112.0 mg/L in the D8 wine, which were much lower than 192.8 mg/L in the W-3 wine. The S13 wine obtained the highest score in terms of color among the three wines in the sensory evaluation, with lower Hunter's L, a, and b values compared to the W-3 wine.

• Journal of Microbiology and Biotechnology
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• v.15 no.3
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• pp.568-572
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• 2005

Saccharomyces yeast spores are more resistant to drying and storage than vegetative cells. For the mass production of yeast spores, compressed yeast was directly inoculated into a sporulation medium (SM). The effects of inoculum size and the addition of rice wine cake (RWC) into SM on the sporulation were examined using flasks. With $1\%$ inoculum of compressed yeast, $1.45{\times}10^8/ml$ of asci was obtained. The addition of $0.5\%$ RWC into SM improved the cell growth and spore yield, and the number of asci formed was $2.31{\times}10^8/ml$. The effects of culture temperature, temperature-shift, and concentrations of inoculum, potassium acetate, and RWC on the sporulation were also evaluated using a jar fermentor. The optimum temperature for spore formation was $22^{\circ}C$ where the number of asci formed was $2.46{\times}10^8/ml$. The shift of culture temperature from initial $30^{\circ}C$ for 1 day to $22^{\circ}C$ for 3 days increased the number of asci formed to $2.96{\times}10^8/ml$. The use of $2\%$ (w/v) inoculum of compressed yeast, $2\%$ potassium acetate, and $1\%$ (w/v) RWC in SM with the shift of culture temperature of initial $30^{\circ}C\;to\;22^{\circ}C$ resulted in $90\%$ sporulation ratio and formation of $6.18{\times}10^8\;asci/ml$.

• Microbiology and Biotechnology Letters
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• v.44 no.3
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• pp.229-235
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• 2016

Korea has a long history of brewing traditional rice wine using a authentic starter culture called nuruk, which contains natural microbial flora. Because rice wine is consumed fresh without filtration, its viable cells contribute to the biological activities of the wine. In numerous studies, microbial strains isolated from rice wine have been screened for their functionalities, which were mainly probiotic properties and antimicrobial activities. Indeed, some lactic acid bacteria (LAB) were confirmed to have strong probiotic activities as well as other health-promoting effects. Moreover, some of the isolated probiotic strains produced functional compounds, such as exopolysaccharides and γ-aminobutyric acid. For antimicrobial activities, some LAB and yeast strains were identified to produce bacteriocins and killer toxins, respectively, with significantly broad spectrum of antimicrobial activity. These functional strains originating from traditional rice wine and their metabolites can be used directly for the production of value-added food products.

• Journal of the Korean Society of Food Culture
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• v.26 no.2
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• pp.178-183
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• 2011

The objective of this study was to determine the quality and sensory characteristics of ginpi wine using different levels of ginpi at each fermentation step. In the first mash with or without ginpi, lactic acid bacteria and yeast counts were maximum between days 2 and 3 of fermentation. The reducing sugar content increased after 2 days of fermentation of the first mash. Brix content increased rapidly after 1 day of fermentation, but pH decreased rapidly. After 3 days of fermentation of the second mash, 0, 30, 60, or 90 g of ginpi were added, and the yeast counts were 8.89, 8.72, 8.81, and 8.88 \log CFU/mL, respectively but then continually decreased. After 3 days of ginpi wine fermentation of the second mash, the addition of 0, 30, 60, 90 g ginpi resulted in alcohol content of 11.40, 8.90, 9.40, and 8.95%, respectively, and after 3 days of fermentation, alcohol content increased slightly. The results of a sensory evaluation showed that overall acceptability of ginpi wine was not different with different levels of added ginpi. However, the flavor of the 90 g ginpi wine had the highest acceptability.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.2
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• pp.254-260
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• 2012

This study was conduced to ferment high quality wine by using Omija fruit. Dry Omija farmed and dried in the Moonkyung area was used in this study. The Omija was soaked in 10~40 folds of distilled water to extract water-soluble components and the fluid was filtered after soaking for 6 hours at $50^{\circ}C$. Strains of alcoholic yeast were isolated respectively from spoiled Omija extract. Isolated alcoholic yeasts, OM-1 and OM-2, showed a round to ellipsoidal shape and formed white or milky white colonies on a solid YM medium. Two yeasts produced 10.33~11.23% alcohol from Omija extract adjusted to $10^{\circ}Brix$ with sugar. Their abilities to ferment alcohol were higher than those of other yeast strains belonging to Saccharomyces cerevisiae such as KCTC 7296 (standard strain of Korean Biological Resources Center), Makgeolli yeast, or beer yeast. The isolates OM-1 and OM-2 showed similar abilities in alcohol fermentation. However, the wine fermented by OM-2 got a better sensory score especially with color. Growth of OM-2 was significantly accelerated by addition of a 0.1% urea and 0.02% mineral mixture. A vitamin mixture was effective for the growth only when urea was added as well.

• Korean Journal of Food Science and Technology
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• v.49 no.6
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• pp.605-609
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• 2017

The effect of malic acid-degrading yeast on the quality of Gaeryangmerou (Vitis spp.) wine obtained from grapes commonly used for making wine in Korea was investigated. Alcoholic fermentation was carried out at $25^{\circ}C$, for 14 days. A malic acid-degrading yeast was used as the experimental sample and a commercial yeast, Fermivin, was used as a control. The fermentation process for the experimental yeast lasted 2-3 days longer than that of Fermivin. The pH and the volatile acid content of the wine were 3.94 and 244.20 mg/L, respectively. The total acid content was 0.86% for the experimental group and 0.94% for the control group. The contents of malic acid and succinic acid in the experimental group were significantly lower than that of the control group (245.61, 50.18 mg% for experimental group versus 302.44, 68.39 mg% for control group, respectively). In contrast, lactic acid content was slightly higher in the experimental group. As expected, the main volatile flavor compounds of Gaeryangmerou wine varied with the yeast used for fermentation and were determined to be isoamyl alcohol, ${\beta}$-phenethyl alcohol, 2-methyl-1-propanol, and diacetyl for the experimental wine.

• The Korean Journal of Food And Nutrition
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• v.10 no.3
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• pp.360-364
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• 1997

Rice Sikhye was fermented by Saccharomyces cerevisiae for 10 day at 29$^{\circ}C$. Fermentable sugars such as glucose, maltose and maltotriose in rice Sikhye were converted into ethanol by the yeast, but limit dextrin was remained after the fermentation. Rice Sikhye wine was found to contain 5.3% of limit dextrin, 6.5% of ethanol, 2.9 $\mu$mol/ml of amino acid, 457$\mu\textrm{g}$/ml of protein, and the acidity of the Sikhye showed 3.1, respectively, and its pH was 3.67. Limit dextrin in rice Sikhye wine showed both signal of $\alpha$-1,4- and $\alpha$-1,6-glucosidic linkage wit its estimation ratio of 5.6:1 by 1H-NMR analysis. The taste of rice Sikhye wine was similar that of wine.

• Proceedings of the Microbiological Society of Korea Conference
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• 2009.05a
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• pp.78-78
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• 2009

$^1H$ NMR spectroscopy coupled with multivariate statistical analysis was used for the first time to investigate metabolic changes in musts during alcoholic fermentation and wines during ageing. Three Saccharomyces cerevisiae yeast strains (RC-212, KIV-1116 and KUBY-501) were also evaluated for their impacts on the metabolic changes in must and wine. Pattern recognition (PR) methods, including PCA, PLS-DA and OPLS-DA scores plots, showed clear differences for metabolites among musts or wines for each fermentation stage up to 6 months. Metabolites responsible for the differentiation were identified to valine, 2,3-butanediol (2,3-BD), pyruvate, succinate, proline, citrate, glycerol, malate, tartarate, glucose, N-methylnicotinic acid (NMNA), and polyphenol compounds. PCA scores plots showed continuous movements away from days 1 to 8 in all musts for all yeast strains, indicating continuous and active fermentation. During alcoholic fermentation, highest levels of 2,3-BD, succinate and glycerol were found in musts with the KIV-1116 strain, which showed the fastest fermentation or highest fermentative activity of the 3 strains, whereas the KUBY-501 strain showed the slowest fermentative activity. This study highlights the applicability of NMR-based metabolomics for monitoring wine fermentation and evaluating the fermentative characteristics of yeast strains.

• Korean Journal of Food Science and Technology
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• v.36 no.5
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• pp.773-778
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• 2004

Properties of wine produced from domestic grape, cultivar Campbell's Early, by carbonic maceration vinification process (CM) were investigated. Process required whole grape clusters without crushing or destemming and no yeast inoculation for fermentation. Fermentation heat was not generated. Yield of wine was 77%, close to that obtained by conventional process, 76%. Acidities of CM wines, free run and pressed wines, and conventional wine were pH 3.6 and 3.3, respectively. Tartaric acid contents of conventional, free run, and pressed wines were 1,813, 4,691, and 5,633 ppm, while those of malic acid were 3,446, 2,077, and 2,275 ppm, respectively. CM could reduce malic acid content by 2/3 that of conventional process. Both processes gave almost equal amounts of citric and acetic acids. CM wines had intense grape aroma and deep purple-blue, natural grape color.