• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.11
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• pp.376-385
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• 2019

This study was undertaken is to isolate brewing yeast suitable for rice beer fermentation from the traditional Nuruk, and to identify the brewing ability of the isolated yeast. After 6 months of research, four brewing yeast isolated from traditional Nuruk showed a normal fermentation pattern in terms of physicochemical data (pH, brix, alcohol content) and higher vitality, as compared to commercial brewing yeast. The concentrations of higher alcohol and ester, that impart the aroma to beer, were 78.4 to 106.5 ppm and 15.1 to 29.3 ppm, respectively. In particular, S. cerevisiae (KCCM 90313) bestowed significantly higher contents of higher alcohol and ester concentrations than rice beer prepared from commercial yeast. We conclude that the four variants of yeast isolated from traditional Nuruk are potentially suitable for manufacturing rice beer. Especially, the S. cevisiae (KCCM 90313) yeast shows excellent yeast activity and aroma production, thereby displaying potential application for manufacturing rice beer in the future.

• Journal of Microbiology and Biotechnology
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• v.20 no.4
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• pp.767-774
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• 2010

In this study, the problems of high caloric content, increased maturation time, and off-flavors in commercial beer manufacture arising from residual sugar, diacetyl, and acetaldehyde levels were addressed. A recombinant industrial brewing yeast strain (TQ1) was generated from T1 [Lipomyces starkeyi dextranase gene (LSD1) introduced, ${\alpha}$-acetohydroxyacid synthase gene (ILV2) disrupted] by introducing Saccharomyces cerevisiae glucoamylase (SGA1) and a strong promoter (PGK1), while disrupting the gene coding alcohol dehydrogenase (ADH2). The highest glucoamylase activity for TQ1 was 93.26 U/ml compared with host strain T1 (12.36 U/ml) and wild-type industrial yeast strain YSF5 (10.39 U/ml), respectively. European Brewery Convention (EBC) tube fermentation tests comparing the fermentation broths of TQ1 with T1 and YSF5 showed that the real extracts were reduced by 15.79% and 22.47%; the main residual maltotriose concentrations were reduced by 13.75% and 18.82%; the caloric contents were reduced by 27.18 and 35.39 calories per 12 oz. Owing to the disruption of the ADH2 gene in TQ1, the off-flavor acetaldehyde concentrations in the fermentation broth were 9.43% and 13.28%, respectively, lower than that of T1 and YSF5. No heterologous DNA sequences or drug resistance genes were introduced into TQ1. Hence, the gene manipulations in this work properly solved the addressed problems in commercial beer manufacture.

• Journal of Microbiology and Biotechnology
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• v.20 no.11
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• pp.1539-1545
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• 2010

In beer, glutathione works as the main antioxidant compound, which also correlates with the stability of the beer flavor. In addition, high residual sugars in beer contribute to major nonvolatile components, which are reflected in a high caloric content. Therefore, in this study, the Saccharomyces cerevisiae GSH1 gene encoding glutamylcysteine synthetase and the Saccharomycopsis fibuligera ALP1 gene encoding ${\alpha}$-amylase were coexpressed in industrial brewing yeast strain Y31 targeting the ${\alpha}$-acetolactate synthase (AHAS) gene (ILV2) and alcohol dehydrogenase gene (ADH2), resulting in the new recombinant strain TY3. The glutathione content in the fermentation broth of TY3 increased to 43.83 mg/l as compared with 33.34 mg/l in the fermentation broth of Y31. The recombinant strain showed a high ${\alpha}$-amylase activity and utilized more than 46% of the starch as the sole carbon source after 5 days. European Brewery Convention tube fermentation tests comparing the fermentation broths of TY3 and Y31 showed that the flavor stability index for TY3 was 1.3-fold higher, whereas its residual sugar concentration was 76.8% lower. Owing to the interruption of the ILV2 gene and ADH2 gene, the contents of diacetyl and acetaldehyde as off-flavor compounds were reduced by 56.93% and 31.25%, respectively, when compared with the contents in the Y31 fermentation broth. In addition, since no drug-resistant genes were introduced to the new recombinant strain, it should be more suitable for use in the beer industry, owing to its better flavor stability and other beneficial characteristics.

• 한국균학회소식:학술대회논문집
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• 2014.10a
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• pp.23-23
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• 2014

There are many yeast strains have been discovered for industrial usage in global scale. In the point of view for the alcoholic fermentation performance and producing alcoholic beverage products, recently many countries have known about the importance of microorganisms as a valuable resource. Discovered with well performed yeasts have potential industrial application in diverse ways such as foods, beverages, cosmetics, pharmaceutical functions, and so on. In Korea, the yeast research has not been sufficiently performed especially for distilled spirits industry. As a result, not so little manufacturers use exotic yeasts from overseas even included the expensive royalties. Besides of those, to produce distilled spirits, many manufacturers do not use specialized yeast for distilled spirits. Distiller's characterized yeasts such as whisky, brandy, vodka, Japanese shochu and awamori, are all well-known industrialized. For decades, the distillers, except us, have selected, developed, and practised yeasts in accordance with distilled spirits characters. This study is about selection and industrial application of yeasts for the Korean pot distilled spirits. Finally 7 yeast strains were selected among over 1,000 yeasts from the traditional Nuruks, through the essential related tests based on brewing and distilling science. The selected yeasts show the appropriate characteristics of distilled spirits. The result of this study could help our distilled spirits industry be activated and stand independent from the exotic microbes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.340-347
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• 2019

This study investigated the brewing properties of rice beer made with yeast isolated from traditional whole wheat nuruk. The experimental method was followed by alcohol fermentation and quality analysis for six months after separating the yeast from nuruk. The yeasts isolated from traditional nuruk showed normal fermentation characteristics, like those of commercial yeast, in terms of alcohol production capability, sugar content, and pH reducing power. Especially, the yeast (KCCM 301) isolated from whole wheat nuruk showed higher contents of glycogen and trehalose than that of commercial yeast, and so KCCM 301 yeast has excellent yeast vitality. Meanwhile, the yeast (KCCM 90301) isolated from traditional Nuruk produced significantly higher alcohol and ester contents than that of commercial yeast. This has a positive effect for supplementing the taste and aroma of rice beer. In conclusion, the yeasts isolated from whole wheat nuruk showed the general alcohol fermentation pattern and aroma content of rice beer. These yeasts seem to be effective in strengthening the flavor of rice beer.

• Applied Biological Chemistry
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• v.14 no.2
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• pp.121-129
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• 1971

During the Brewing of Soy Sauce on an industrial scale, Saccharomyces rouxii $T_9$ was cultured and added to the soy sauce mash. The comparative experiments of soy sauce mash in non-addition and addition group of yeast were examined in this report. The yeast flora and chemical composition of Soy sauce mash through out the brewing were observed and the results obtained were as follows. (1) The number of Osmophilic yeast in one ml of soy sauce mash showed $185{\times}10^3$ 1 month after mashing and $750{\times}10^3$ 4 months after mashing in case of yeast group, while presented as $98{\times}10^3$ 1 month after mashing and $394{\times}10^3$ 4 months after mashing in case of non-yeast group. And the number of Osmphilic yeast in yeast group was twice of that in non-yeast group. (2) The number of ordinary yeast of TTC red group was shown as $2132{\times}10^3\;to\;3252 ×10^3$ 5 to 6 months after mashing in case of yeast group, while presented $752{\times}10^3\;to\;1251{\times}10^3$ in case of non-yeast group. And the yeast group was shown more than non-yeast group in ordinary, red pink and pink yeast number. (3) TTC red yeast were strongly appeared in both addition and non-addition group of yeast from 1 month after mashing to 6 months after mashing. (4) Though total nitrogen, pure extract, pH and buffer action contents of soy sauce showed similiar tendency in yeast and non-yeast group, alcohol and color density contents were highly appeared in yeast group and reducing sugar content was in non-yeast group respectively. (5) By the results of Organic function test of soy sauce mash, the difference of taste quality in yeast and non-yeast group were not evidently appeared, however, the appearance and flavour of the soy sauce were better in yeast group than in non-yeast group.

• The Microorganisms and Industry
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• v.20 no.2
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• pp.46-48
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• 1994

The aim of the sutdy is to collect a variety of wild yeasts from different regions in Korea and in different seasons and to account for the natural patterns of regional and seasonal variation that they display. From the specimens collected in this study, more useful strains are expected to be discovered, which can be cultivated and utilized fro industrial development. The study attempts to determine the degree to which utilizable yeasts can be applied in brewing, confectionary, baking, the manufacture of medicine, and as feed yeast. Such findings would contribute not only to the development of academic research, but would also be important in obtaining raw material that can be applied in our daily lives and in industrial development in response to the demands of the times.

• KSBB Journal
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• v.14 no.2
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• pp.181-187
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• 1999

We have investigated industrial media for lactic acid fermentation to reduce the cost of nitrogen sources. Corn steep liquor (CSL) was successfully used at 5% (v/v) in batch fermentations. Use of soluble CSL improved the productivity about 20% with an advantage of clearer fermentation broth. Yeast extract-complemented CSL improved the productivity about 20% with an advantage of clearer fermentation broth. Yeast extract-complemented CSL media further increased the increased the productivity. It was found that 3.1 g/L yeast extract and 5% CSL could be an effective substitute for 15 g/L yeast extract in 10% glucose medium. Brewing yeast was also used as a sole nitrogen source equivalent to 5% CSL. A continuous culture coupled with cell-recycle by microfiltration at the dilution rate of 0.05-0.065 h-1 led to the highest lactic acid productivity. Lactic acid was recovered by electrodialysis from the cell free broth. Depleted cell free broth supplemented with 5-10 g/L of yeast extract performed reasonably in batch and continuous cultures. Reuse of the fermentation broth may reduce the cost of raw materials as well as minimize the fermentation wastes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.8
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• pp.5468-5475
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• 2015

This present work was aimed to analyse characteristics of fermentation and aging of Korean traditional cheongju prepared by adding of different brewing water. The three different mashes were used for fermentation and maturation. The cheongju(A) was prepared without adding of brewing water in two stage mashing. Cheongju(B) and cheongju(C) were made with adding of 1 liter and 2 liter brewing water in two stage mashing respectively whereas the cheongju(B) and cheongju(C) showed higher fermentation ability than that of cheongju(A) regarding to pH, ethanol, specific gravity and sugar concentration(brix). In terms of volatile compounds content after six months aging, cheongju(A and B) prepared by adding brewing water showed the higher content of ethyl acetate than that of cheong(C) and the concentrations were maintained during the aging period. In addition, the content of fusel oil(n-propanol, i-butanol, n-butanol, i-bmyl alcohol, n-bmyl alcohol)indicated similar pattern as ethyl acetate. The organic acid of cheongju B(4873.46 mg/l) and C(4963.12 mg/l) also indicated the higher content than that of cheongju A(4661.47 mg/l). In conclusion, cheongju B and C prepared by adding brewing water in two stage mashing showed better quality and taste than that of cheongju A.

• Korean Journal of Microbiology
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• v.10 no.2
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• pp.51-68
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• 1972

The aim of the sutdy is to collect a variety of wild yeasts from different regions in Korea and in different seasons and to account for the natural patterns of regional and seasonal variation that they display. From the specimens collected in this study, more useful strains are expected to be discovered, which can be cultivated and utilized fro industrial development. The study attempts to determine the degree to which utilizable yeasts can be applied in brewing, confectionary, baking, the manufacture of medicine, and as feed yeast. Such findings would contribute not only to the development of academic research, but would also be important in obtaining raw material that can be applied in our daily lives and in industrial development in response to the demands of the times.