• 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 the East Asian Society of Dietary Life
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• v.26 no.6
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• pp.543-549
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• 2016

The objective of this study was to investigate quality properties of 'Cheonghyang' wine using different commercial yeast strains. Soluble solid content, pH level and total acidity of 'Cheonghyang' grape were $20^{\circ}Bx$, pH 3.5 and 0.66%, respectively. Total acidity ranged from 0.91~1.06% in the middle stage of fermentation and decreased to 0.77~0.82% when alcoholic fermentation finished. Alcohol content in wines ranged from 12.5% to 12.9% showing no significant difference in yeast strains. Wine fermented with Red Fruit had high volatile acid content (189.0 mg/L) whereas wine fermented with Fermivin indicated low volatile acid content (77.7 mg/L). Wines made with Montrachet, Fermivin and Aroma White had low brightness (L-value) compared to others. Results from sensory evaluation demonstrated that commercial wine yeasts, Montrachet and Fermivin, can be applied to improve sensory properties of 'Cheonghyang' wine such as aroma, acidity and transperency. On the other hand, preferences of wine fermented with EC-1118 strain containing lots of tannins and total polyphenols were significantly reduced.

• Korean journal of food and cookery science
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• v.20 no.5
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• pp.529-536
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• 2004

In this study, the author examined the fermentative abilities and baking properties of commercial baker's yeasts and suggested the fundamental data for the development of the yeast products industry. Carbon dioxide production, expansion abilities of doughs, and maltose fermentative abilities were measured with commercial yeasts. The fermentative abilities of various bread doughs were determined in comparison to a reference yeast and a selected yeast from commercial yeast. Various breads were prepared by these two yeasts and their sensory properties were evaluated. Y7, followed by Y5 and Y4, showed higher ability than any other commercial yeasts in the gassing power of the dough, as measured by a Meissle fermenter. In the expansion abilities of the doughs made from various yeasts by M-Cylinder, Y7, followed by Y4 and Y5, showed the best expansion ability the results were similar to those for gassing power. Therefore, Y7 was selected. The maltose fermentative abilities of various yeasts in Atkin's liquid medium showed a higher value in Y5, Y7 and Y 4. Selected yeast Y7 and the reference yeast K were used for determining the fermentative abilities of various bread doughs. For the various breads prepared by K and Y7, the qualities of the breads such as volume, weight and specific volume were measured. The volume by Y7 was higher in the straight dough bread, and that by K was higher in the sponge dough bread. In the sweet dough bread, both Y7 and K were excellent groups for it. Sensory properties of various breads made from K scored high on the items such as external properties and color in the straight dough bread. It also acquired a good score on the item of the crusts in the sweet dough bread. The overall acceptability of Y7 and K were similar.

• Journal of the East Asian Society of Dietary Life
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• v.11 no.5
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• pp.393-399
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• 2001

Effects of various types of salts (commercial low salt, sea salt, refined salt, and bamboo salt) and concentrations (0, 3.0 and 5.0% ) on the growth of yeasts isolated from Kimchi were investigated. The isolated yeasts used in the study are as follows : Saccharomyces cerevisia, Sporobolomyces albo-rubescens, Issatchenkia orientalis Cryptococcus luteolous, Ustilago maydis, Candida humilis, Pichia onychis, Cadida nitratophila, and Pichia jadinii. The growths of the yeasts were inhibited against each salt concentration. The growths of Candida sp. isolated from the later stage of fermentation was strongly inhibited against 5% concentration of salt. On the other hand the induction phase of Issatchenkia orientalis isolated at the early stage of fermentation was the quickest among all the tested yeasts. Among the salts, bamoo salt was found to be strongest inhibitor of the growth of yeasts.

• Journal of Microbiology and Biotechnology
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• v.24 no.4
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• pp.497-506
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• 2014

In this study, crude glycerol was used as a carbon source in the cultivation of wild yeasts, aiming at the production of microbial lipids and citric acid. Forty yeasts of different sources were tested concerning their growth in crude and commercial glycerol. Four yeasts (Lindnera saturnus UFLA CES-Y677, Yarrowia lipolytica UFLA CM-Y9.4, Rhodotorula glutinis NCYC 2439, and Cryptococcus curvatus NCYC 476) were then selected owing to their ability to grow in pure ($OD_{600}$ 2.133, 1.633, 2.055, and 2.049, respectively) and crude ($OD_{600}$ 2.354, 1.753, 2.316, and 2.281, respectively) glycerol (10%, 20%, and 30%). Y. lipolytica UFLA CM-Y9.4 was selected for its ability to maintain cell viability in concentrations of 30% of crude glycerol, and high glycerol intake (18.907 g/l). This yeast was submitted to lipid production in 30 g/l of crude glycerol, and therefore obtained 63.4% of microbial lipids. In the fatty acid profile, there was a predominance of stearic (C18:0) and palmitic (C16:0) acids in the concentrations of 87.64% and 74.67%, respectively. We also performed optimization of the parameters for the production of citric acid, which yielded a production of 0.19 g/l of citric acid in optimum conditions (38.4 g/l of crude glycerol, agitation of 184 rpm, and temperature of $30^{\circ}C$). Yarrowia lipolytica UFLA CM-Y9.4 presented good lipid production when in the concentration of 30 g/l of glycerol. These data may be used for production in large quantities for the application of industrial biodiesel.

• The Korean Journal of Food And Nutrition
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• v.10 no.1
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• pp.97-101
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• 1997

Gas formation, and container swelling and explosion during the distribution of commercial soy sauce is an important problem to be solved. Six yeasts were isolated from soy sauce returned because of container swelling. Three isolates (SS-1, SS-2, SP-1) formed film on soy sauce while others did not. Five isolates(SS-1, SS-2, SS-4, SP-1, SP-2) actively fermented soy sauce to produce gas and all were identified as Zygosaccharomyces rouxii, and one other isolate (SS-3) fermented soy sauce very weakly and was identified as Candida globosa.

• Mycobiology
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• v.40 no.2
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• pp.138-141
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• 2012

We measured physiological functionalities, including antihypertensive angiotensin I-converting enzyme inhibitory activity and immun-stimulating ${\beta}$-glucan content for sixty kinds of Makgeolli that is commercially available from the market. As a result, we selected R-12 commercial raw Makgeolli, with a high content of immuno-stimulating ${\beta}$-glucan, and R-14 commercial raw Makgeolli, exhibiting high antihypertensive activity. Due to the similarities in their overall physicochemical properties and raw materials used for fermentation, we compared the microbial flora in order to investigate the reason for the differences in their functionalities. Nested PCR and denaturing gradient gel electrophoresis for yeasts and bacteria were performed for analysis of microbial diversity of two different kinds of Makgeolli (i.e., R-12, R-14), which showed immuno-stimulating ${\beta}$-glucan content and exhibited a very high level of antihypertensive activity, respectively. Analysis of the 18S rDNA amplicon revealed a major presence of the yeast strain Pichia burtonii in every Makgeolli sample. Analysis of the 16S rDNA amplicon revealed a predominance of lactic acid bacteria, and the most frequent lactic acid bacteria were Lactobacillus ingluviei, L. fermentum, and L. harbinensis, and Lactobacillus sp. Among these, L. harbinensis was detected only in R-12 and L. ingluviei was found only in R-14. Different functionalities from the individual commercially available Makgeolli may be attributed to actions of different microbial flora during fermentation.

• Mycobiology
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• v.39 no.1
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• pp.33-39
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• 2011

Wild yeasts on the surface of various fruits including grapes were surveyed to obtain yeast strains suitable for fermenting a novel wine with higher alcohol content and supplemented with rice starch. We considered selected characteristics, such as tolerance to alcohol and osmotic pressure, capability of utilizing maltose, and starch hydrolysis. Among 637 putative yeast isolates, 115 strains exhibiting better growth in yeast-peptone-dextrose broth containing 30% dextrose, 7% alcohol, or 2% maltose were selected, as well as five ${\alpha}$-amylase producers. Nucleotide sequence analysis of the 26S rDNA gene classified the strains into 13 species belonging to five genera; Pichia anomala was the most prevalent (41.7%), followed by Wickerhamomyces anomalus (19.2%), P. guilliermondii (15%), Candida spp. (5.8%), Kodamaea ohmeri (2.5%), and Metschnikowia spp. (2.5%). All of the ${\alpha}$-amylase producers were Aureobasidium pullulans. Only one isolate (NK28) was identified as Saccharomyces cerevisiae. NK28 had all of the desired properties for the purpose of this study, except ${\alpha}$-amylase production, and fermented alcohol better than commercial wine yeasts.

• Korean Journal of Microbiology
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• v.12 no.1
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• pp.31-36
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• 1974

Four strains of yeasts were chosen from those isolated previously, and a strain from 160 isolates collected in this year were examined for the treatment of pulp waste liquor. Experiments about optimum nutrient condition, composition of cells, and reduction of B.O.D. on the "S" pulp industry waste liquor were performed with 5 strains. 1. The isolates(strain 112) was identified as Candida utilis. 2. The optium concentration of 4 components of nutrients were ($NH_4$)$SO_2$lg/l, yeast extract 70mg/l, $KH_2PO_4$ 300mg/l, and $MgSO_4{\ddot}7H_2O$ 500mg/l. 3. Specific growth ratio of Candida utilis KYRI 112 was 0.48/hr at optimum nutrient media and the yield was 0.45%(V/V). 4. Endomycopsis capsularis KYRI 613 contained more crude protein than the most of commercial yeasts. 5. The B.O.D. of waste liquor was reduced ro 20% of its value by the culture.e culture.

• Journal of Microbiology and Biotechnology
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• v.32 no.3
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• pp.307-316
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• 2022

Yeasts play an important role in spontaneous fermentation of traditional alcoholic beverages. Our previous study revealed that a mixed-consortia of both Saccharomyces and non-Saccharomyces yeasts were responsible for fermentation of khadi, a popular, non-standardized traditional beverage with an immense potential for commercialization in Botswana. Functional characterization of isolated fermenting yeasts from mixed consortia is an indispensable step towards the selection of potential starter cultures for commercialization of khadi. In this study, we report the characterization of 13 khadi isolates for the presence of brewing-relevant phenotypes such as their fermentative capacity, ability to utilize a range of carbon sources and their ability to withstand brewing-associated stresses, as a principal step towards selection of starter cultures. Khadi isolates such as Saccharomyces cerevisiae, Saccharomycodes ludwigii and Candida ethanolica showed good brewing credentials but Lachancea fermentati emerged as the isolate with the best brewing attributes with a potential as a starter culture. However, we were then prompted to investigate the potential of L. fermentati to influence the fruity aromatic flavor, characteristic of khadi. The aroma components of 18 khadi samples were extracted using headspace solid phase micro-extraction (HS-SPME) and identified using a GC-MS. We detected esters as the majority of volatile compounds in khadi, typical of the aromatic signature of both khadi and L. fermentati associated fermentations. This work shows that L. fermentati has potential for commercial production of khadi.