• The Korean Journal of Food And Nutrition
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• v.11 no.2
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• pp.143-149
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• 1998

Sugars in Korean beer(3 brands) and Japanese beer(21 brands) were studied by HPLC and TLC. Total sugar of beer were estimated to 1.71∼3.93%(average 3.15%). Ethanol 4.5% class beers were estimated to 3.24% for Korean brands and 2.5% for Japanese brands. Ethanol 5% and 5.5% class beer were estimated to contain 3.2% for Japanese brands, respectively. Maltooligosaccharide series from glucose to maltodecaose were detected in the test of TLC and HPLC. No fermentable maltooligosaccarides and limit dextrin were estimated to 2.32%. But sugars in Korean Sikhye, rice drink saccharifide by malt, were not detected maltooligosaccharide series form maltotetraose to maltoheptaose.

• The Korean Journal of Food And Nutrition
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• v.30 no.3
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• pp.491-500
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• 2017

Sweet potato-malt worts were prepared by using sweet potato paste of Shinyulmi and Shinjami as the main adjunct, enzymes, malt, hop, and water. We brewed low-malt beers of the lager- or ale-type by using these worts and inoculating bottom and top fermenting yeast, respectively. Moreover, the componential and functional characteristics of the resulting beers were evaluated. During saccharification of sweet potato, the addition of an enzyme agent containing ${\alpha}-amylase$ caused an improvement in filterability and an increase of total sugar. The sugar content of sweet potato-malt wort which was prepared by the addition of 0.1% enzyme agent containing ${\alpha}-amylase$ and a three-step infusion procedure was $13.5^{\circ}Brix$ adequate for beer brewing. The polyphenol and anthocyanin contents of Shinjami beer were increased with increasing content of the paste, and also increased DPPH and ABTS radical scavenging activities. But in Shinyulmi beer it were decreased. A strong correlation was obserbed between antioxidave activities and polyphenol and anthocyanin contents of sweet potato beers. In all lager- and ale-type low-malt beers using 41.6% of Shinjami pastes, sensory attributes very similar to those of 100% malt beer were obtained and they were very good as they had unique red color.

• 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.

• 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.

• 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.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.62 no.2
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• pp.113-117
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• 2017

The purpose of this study was to evaluate the effects of rice cultivars (Hangaru, Seolgaeng, Dasan-1 and Anda) on the quality characteristics of rice beer. Hangaru and Seolgaeng which are soft rice varieties, had moisture contents that were 14.48% and 14.62% higher than those of Dasan-1 and Anda, respectively. Dasan-1 and Anda showed higher protein contents than those of the other two varieties. The amylose content of Hangaru was found to be 17.71% lower than that of the other varieties, whereas the reducing sugar content of Hangaru and Seolgaeng was higher than that of Dasan-1 and Anda. Hardness measurements for Hangaru and Seolgaeng were lower than those for Dasan-1 and Anda. Measurements of the alcohol content, pH and color of beers brewed using these rice cultivars revealed no significant difference among the cultivars. However, measurement results for bitterness showed that beers brewed with Hangaru and Seolgaeng had lower bitterness than did the beers brewed with Dasan-1 and Anda. The results of this study indicate that Hangaru and Seolgaeng can be considered as cultivars with brewing qualities suitable for rice beer.