• Korean Journal of Food Science and Technology
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• v.52 no.5
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• pp.529-537
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• 2020

This study was carried out to confirm changes in the microbial community and physicochemical characteristics of Korean traditional Makgeolli during fermentation by yeast as a fermentation starter. We demonstrate that the microbial community during fermentation affects the quality of Makgeolli. At the species level, Pediococcus pentosaceus, Weissella confusa, Pantoea vagans, and Lactobacillus graminis were dominant on fermentation mix, after 1-2 days, in the control group without yeast treatment. Acid production in the control group was higher than that in the yeast-treated group. P. pentosaceus was dominant throughout the fermentation process, and the proportion of P. vagans remarkably decreased following yeast addition. Considering quality characteristics, the alcohol content rapidly increased after yeast addition, and the lactic acid content was lower in the yeast-treated group than in the control. These results suggest that the rapid increase in alcohol at the start of fermentation inhibits the growth of lactic acid-producing bacteria. The addition of yeast may contribute to the reduction in the high amount of lactic acid, which can be one of the causes of changes in Makgeolli quality.

• Journal of Korean Medicine Rehabilitation
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• v.20 no.4
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• pp.17-31
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• 2010

Objectives : Ganoderma Lucidum has been used in traditional oriental medicine to treat various conditions including chronic fatigue and cough. This experimental study was designed to investigate the effects of yeast-fermented Ganoderma Lucidum extract on the fatigue of rats elicited by forced swimming. Materials and methods : The rat subjects were divided into 4 groups: normal group, control group administered with 0.9% normal saline, experimental I(Exp I) group administered with yeast-fermented Ganoderma lucidum extract and experimental II(Exp II) group administered with Ganoderma lucidum extract for 4 weeks. All the serum samples collected by heart puncture were used to measure biochemical factors such as glucose, lactate, lactate dehydrogenase(LDH), creatine kinase(CK), inorganic phosphorus, ammonia, total cholesterol(TC), triglycerides(TG), high-density lipoprotein(HDL), low-density lipoprotein(LDL), aspartate transaminase(AST), alanine transaminase(ALT). Results : 1. Weight change and swimming time were not significantly different in the experimental groups as compared with control group. 2. Lactate was significantly decreased in the experimental groups as compared with control group. Inorganic phosphorus was also significantly decreased in the Exp I group as compared with control group(p<0.05). 3. Serum lipid concentration was not significantly different in the experimental groups as compared with control group. 4. AST and ALT were significantly decrease in the experimental groups as compared with control group. Conclusions : Yeast-fermented Ganoderma lucidum in forced swimming rats would appear to reduce fatigue-related factors, AST, ALT of serum and promote anti-fatigue effect.

• Journal of Microbiology and Biotechnology
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• v.20 no.12
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• pp.1702-1710
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• 2010

Korean traditional rice wines yakju and takju are generally brewed with nuruk as the source of the saccharogenic enzymes by natural fermentation. To improve the quality of Korean rice wine, the microorganisms in the nuruk need to be studied. The objective of this research was to improve the quality of Korean wine with the wild-type yeast strains isolated from the fermentation starter, nuruk. Only strain YA-6 showed high activity in 20% ethanol. Precipitation of Y89-5-3 was similar to that of very flocculent yeast (>80%) at 75.95%. Using 18S rRNA sequencing, all 10 strains were identified as Saccharomyces cerevisiae. Volatile compounds present in yakju were analyzed by gas chromatography-mass selective detector. The principal component analysis (PCA) of the volatile compounds grouped long-chain esters on the right side of the first principal component, PC1; these compounds were found in yakju that was made with strains YA-6, Y89-5-3, Y89-5-2, Y90-9, and Y89-1-1. On the other side of PC1 were short-chain esters; these compounds were found in wines that were brewed with strains Y183-2, Y268-3, Y54-3, Y98-4, and Y88-4. Overall, the results indicated that using different wild-type yeast strains in the fermentation process significantly affects the chemical characteristics of the glutinous rice wine.

• Journal of Microbiology and Biotechnology
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• v.23 no.1
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• pp.40-46
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• 2013

A variety of nuruk were collected from various provinces in Korea, and their microflora profiles were analyzed at the species level. A total of 42 nuruk samples were collected and when the viable cell numbers in these nuruk were enumerated, the average cell numbers of bacteria, fungi, yeast, and lactic acid bacteria from all nuruk were 7.21, 7.91, 3.49, and 4.88 log CFU/10 g, respectively. There were no significant differences in viable cell numbers of bacteria or fungi according to regions collected. Bacillus amyloliquefaciens and B. subtilis were the predominant bacterial strains in most samples. A significant portion, 13 out of 42 nuruk, contained foodborne pathogens such as B. cereus or Cronobacter sakazakii. There were various species of lactic acid bacteria such as Enterococcus faecium and Pediococcus pentosaceus in nuruk. It was unexpectedly found that only 13 among the 42 nuruk samples contained Aspergillus oryzae, the representative saccharifying fungi in makgeolli, whereas a fungi Lichtheimia corymbifera was widely distributed in nuruk. It was also found that Pichia jadinii was the predominant yeast strain in most nuruk, but the representative alcohol fermentation strain, Saccharomyces cerevisiae, was isolated from only 18 out of the 42 nuruk. These results suggested that a variety of species of fungi and yeast were distributed in nuruk and involved in the fermentation of makgeolli. In this study, a total of 64 bacterial species, 39 fugal species, and 15 yeast species were identified from nuruk. Among these strains, 37 bacterial species, 20 fungal species, and 8 yeast species were distributed less than 0.1%.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.1
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• pp.41-46
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• 2004

A correlation between fibrinolytic activity and microflora in Korean traditional soybean fermented food was investigated. The fibrinolytic activities of traditional soybean pastes and commercially processed samples were 2.42$\pm$1.01 unit/g and 1.58$\pm$0.98 unit/g, respectively. The cell density of Bacillus in traditional soybean pastes was about 10$^{7}$ CFU/g and its commercially processed one was 10$^{6}$ CFU/g. Acid producing bacteria, fungi and yeast group were higher in commercially processed one. The correlations of fibrinolytic activity and microflora in traditional and commercial Doenjang were positively correlated in Bacillus ($R^2$≒ 0.69), negatively correlated in fungal group ($R^2$≒0.40), and there were no significant correlations in acid forming bacteria and yeast group ($R^2$<0.16). Fibrinolytic activities in Meju and Koji were 6.54$\pm$1.97 unit/g and 1.46$\pm$0.43 unit/g respectively, and were positively correlated with Bacillus. Yeast and acid forming bacteria were grown by 5∼6 decimal induction during fermentation period of Doenjang, but Bacillus, fungal cells and fibrinolytic activity were nearly stable. Results indicate that fibrinolytic activity of Doenjang depends on enzyme induction in Meju or Koji processing by Bacillus, Doenjang fermentation process.

• Journal of Food Hygiene and Safety
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• v.19 no.4
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• pp.209-216
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• 2004

Dry rehydratable film methods were compared to conventional methods for the enumeration of microorganisms in Korean traditional foods. Kimchi, doenjang, kochujang, kanjang, takju, sujeongkwa and sikhe were used as Korean traditional foods. $Petrifilm^{TM}$ aerobic count plate, $Petrifilm^{TM}$ coliform count plate, $Petrifilm^{TM}$ E. coli/coliform count plate, $Petrifilm^{TM}$ yeast and mold count plate and $Petrifilm^{TM}$ staph express count plate were compared to plate count agar, most probable number (MPN) for coliform, MPN for E. coli, potato dextrose agar and coagulase test, respectively. Regression analysis indicated that correlation coefficient values were 0.974-0.998, 0.913-0.995, 0.955-0.978, 0.968-0.986 and 0.998-0.999 for total aerobic bacteria, yeast and mold, coliform, E. coli and S. aureus, respectively. There were no significant differences between two methods, suggesting that $Petrifilm^{TM}$ plates can be used as an alternative to conventional method for the determination of microorganisms in Korean traditional foods.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.6
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• pp.840-846
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• 2015

We investigated blueberry wine made using traditional yeast (Saccharomyces cerevisiae M-5) and Saccharomyces cerevisiae Fermivin which is widely used in wine manufacturing, and measured its fermentative characteristics and antioxidant activity. S. cerevisiae M-5 is a traditional yeast isolated from domestically grown Black raspberry (Rubus occidentalis). Both S. cerevisiae M-5 and Fermivin were inoculated into blueberry juice (BBJ) up to $1{\times}10^9CFU/kg$, followed by incubation at $25^{\circ}C$ for 39 days. Final fermentation products of blueberry fermented with S. cerevisiae M-5 (BBM) presented 13.10% alcohol, $8.42^{\circ}Bx$ of sugar, and 1.183% acidity, and final fermentation products of blueberry fermented with Fermivin (BBF) presented 14.20% alcohol, $8.2^{\circ}Bx$ of sugar, and 1.153% acidity. The contents of total polyphenol and flavonoid compounds of BBM were higher than those of BBF and BBJ. DPPH and ABTS radical scavenging activities and reducing power of BBM were higher than those of BBF. The sensory evaluation revealed that BBM showed excellent flavor, taste, and overall acceptability compared with BBF. Based on these results, the possibility of industrial utilization of S. cerevisiae M-5 as traditional yeast was confirmed by sensory evaluation and antioxidant activity. Fermentation rate of S. cerevisiae M-5 was similar to Fermivin, which is used in the food industry.

• Biotechnology and Bioprocess Engineering:BBE
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• v.6 no.5
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• pp.337-340
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• 2001

A galactooligosaccharide(GalOS)-producing yeast, OE-20 was selected from forty seven strains of yeast growing in Korean traditional Meju (cooked soybean) and the yeast was tentatively identified as Kluyveromyces maxianus var lactis by its morphology and fermentation profile. A maximum yield of 25.1%(w/w) GalOS, which corresponds to 25.1 g of GalOS per liter, was obtained from the reaction of 100 g per liter of lactose solution at 3$0^{\circ}C$, pH 7.0 for 18 h with an intracellular crude $\beta$-galactosidase. Glucose and galactosidase were found to inhibit GalOS formation. The GalOS that were purified by active carbon and celite 545 column chromatography were supplemented in MRS media and a stimulated growth was observed of some intestinal bacteria. In particular the growth rate of Bifidobacterium infantis in the GalOS containing MRS broth increased up to 12.5% compared to that of the MRS-glucose broth during a 48h incubation period.

• Food Science and Biotechnology
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• v.15 no.2
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• pp.298-302
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• 2006

Kochujang was fermented using hot red pepper, meju prepared with soybean and rice, and malt-digested syrup. To reduce salt content, mustard powder (1.2%, w/w) was added to Korean traditional kochujang with 4-10% salt, and microbial characteristics, enzyme activities, and gas formation in kochujang were evaluated during fermentation for 120 days at $25^{\circ}C$. Yeast numbers of all treatments maintained 2.43-2.86 log CFU/g up to 60 days fermentation, indicating salt concentration had no effect on yeast count. Activities of ${\alpha}$- and ${\beta}$-amylases, and neutral and acidic proteases of kochujang added with mustard powder were slightly higher than those of control group. Total accumulative volume of gas produced during fermentation of kochujang without mustard powder (control group) was 5,892 mL/pack, but decreased to 34-99 mL/pack in low-salted kochujang (4 and 6% salt) added with mustard powder. Major gas produced was carbon dioxide (79-80%) with oxygen content less than 1.25%(v/v). Results indicate salt concentration of kochujang could be lowered up to 6-8% by addition of mustard powder without gas formation and quality alteration during distribution.

• Mycobiology
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• v.41 no.3
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• pp.139-144
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• 2013

Makgeolli is a traditional cloudy-white Korean rice wine with an alcohol content of 6~7%. The present study investigated the morphological characteristics, carbon-utilizing ability, fatty acid composition, alcohol resistance, glucose tolerance, and flocculence of Saccharomyces cerevisiae Y98-5 and Pichia anomala Y197-13, non-S. cerevisiae isolated from Nuruk, which is used in brewing Makgeolli. Similar morphological characteristics were observed for both isolated wild yeast strains; and the carbon source assimilation of Y197-13 differed from that of other P. anomala strains. Strain Y197-13 was negative for D-trehalose, mannitol, arbutin, I-erythritol, and succinic acid. The major cellular fatty acids of strain Y197-13 included C18:2n6c (33.94%), C18:1n9c (26.97%) and C16:0 (20.57%). Strain Y197-13 was Crabtree-negative, with 60% cell viability at 12% (v/v) ethanol. The flocculation level of strain Y197-13 was 8.38%, resulting in its classification as a non-flocculent yeast.