• Korean Journal of Microbiology
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• v.11 no.4
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• pp.167-174
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• 1973

This study included two parts of investigation, the microfloral changes during the brewing process with the changes of pH, total acidity, temperature and alcoholic contents, as well as determination of survival times of major enteric pathogens in Takju. 1. Maximum number of Saccharomyces cerevisiae was $4.3{\times}10^7$ per milliliter on the 5th day of fermentation and gradually decreased. Saccharomyces cerevisiae was one of the predominant strains of the fermentation process. The number of Saccharomyces cerevisiae was $4.3{\times}10^6$ per milliliter at the completion of the brewing and human consumption. In a few days after the completion of the brewing. Bacillus subtilis and some species of Staphylococcus spp. began to grow and those organisms were responsible for the spoilage. 2. Maximum pH, during the brewing, was 5.8 on the first day of fermentation and rapidly decreased until 6th day of fermentation at pH 4.3. 3. Maximum alcholic content was 14.5 degree on the 4th day of fermentation, 10.3 degree on the 5th day and this degree was continued during the experimentation. 4. Maximum temperature, during Takju brewing was 34.deg.C on the 3rd day of fermentation and rapidly decreased up to 23.deg.C on the 6th day and this temperature was continued until the brewing process was finished. 5. Maximum total acidity was 0.57 percent on the 4th day of fermentation and gradually decreased by brewing process was completed. 6. Survival time of major enteric pathogenic bacteria in Takju was as follows : Shigella dysenteriae and Escherichia coli were isolated in two hours and 14 hours respectively, but Salmonella typhi, Vibrio parahemolyticus were not isolated even in an hour after the inoculation of those organisms in undiluted Takju. In diluted Takju, Salmonella typhi, Vibrio parahemolyticus were not isolated even in an hour after the inoculation of those organisms in undiluted Takju. In diluted Takju, Salmonella typhi, Shigella dysenteriae, and Escherichia coli were survived for 50-60 hours, but Vibrio cholerae and Vibrio parahemolyticus were not isolated even if treated within one hour.

• Journal of Food Hygiene and Safety
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• v.32 no.1
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• pp.27-34
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• 2017

Effect of salt concentration (10, 20 and 30%, respectively) and fermentation temperature (10 and $20^{\circ}C$, respectively) on changes in quality index (VBN, Histamine, Amino nitrogen, Total viable cell counts, Coliform bacteria and E. coli counts) of culinary salted and fermented anchovy during fermentation were investigated to suggestion of fundamental documents for industrial objectives. Our results show that the effect of salt concentration on changes in quality index was not high compared with fermentation temperature in salted and fermented anchovy with below 20% of salt concentration however effect of salt concentration and fermentation temperature on quality index was not significant with 30% salt concentration. And all most whole changes of quality index were rapidly increased or decreased for 30 days of fermentation.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.1
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• pp.155-159
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• 2016

The objective of this study was to investigate the effect of fermentation temperature on quality characteristics of apple wine. Apple wine mashes were fermented in 15, 20, and $25^{\circ}C$ water bathes for 9 days. The pH levels of all samples were below 4 from 24 h of fermentation until the end. Total acidities of 0.05% acetic acid solution were 7.8, 7.4, and 7.0% in the 15, 20, and $25^{\circ}C$ fermented samples, respectively. The evaporation of esters generated by combining alcohol and organic acids might be the reason for lower total acidity for high temperature fermentation. Alcohol contents of the 20 and $25^{\circ}C$ fermented samples were 6.5 and 6.6% (v/v), respectively, whereas that of the $15^{\circ}C$ fermented sample was 5.6% (v/v) and significantly lower than the others (P<0.05). Methanol contents were 0.68, 0.82, and 1.69 mg/L in the 15, 20, and $25^{\circ}C$ fermented samples, respectively. Fermentation at higher temperatures generated higher methanol content in apple wine. On the other hand, acetaldehyde contents were 3.43, 2.39, and 1.02 mg/L in the 15, 20, and $25^{\circ}C$ fermented samples, respectively, due to the lower boiling point of acetaldehyde ($20.2^{\circ}C$). Based on the results, a fermentation temperature of $20{\sim}25^{\circ}C$ is effective for apple wine fermentation.

• Journal of Food Hygiene and Safety
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• v.32 no.5
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• pp.355-362
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• 2017

Fermentation temperature (10 and $20^{\circ}C$) and salt concentration (10, 20, and 30%) on volatile basic nitrogen (VBN), histamine, amino nitrogen, total viable cell counts, coliform bacteria and Escherichia coli counts as the quality index in salted shrimp were investigated during fermentation. Results show that the effect of salt concentration on changes in quality index was not high compared with fermentation temperature (10 and $20^{\circ}C$) in salted shrimp treated with 10% and 20% salt concentration. However, effect of salt concentration and fermentation temperature on the quality index was not significant with 30% salt concentration. And all most whole changes of quality index were rapidly increased or decreased for 30 days of fermentation.

• Journal of Microbiology and Biotechnology
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• v.30 no.10
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• pp.1574-1582
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• 2020

Flavonoids have diverse biological functions in human health. All flavonoids contain a common 2-phenyl chromone structure (C6-C3-C6) as a scaffold. Hence, in using such a scaffold, plenty of high-value-added flavonoids can be synthesized by chemical or biological catalyzation approaches. (2S)-Naringenin is one of the most commonly used flavonoid scaffolds. However, biosynthesizing (2S)-naringenin has been restricted not only by low production but also by the expensive precursors and inducers that are used. Herein, we established an induction-free system to de novo biosynthesize (2S)-naringenin in Escherichia coli. The tyrosine synthesis pathway was enhanced by overexpressing feedback inhibition-resistant genes (aroG^fbr and tyrA^fbr) and knocking out a repressor gene (tyrR). After optimizing the fermentation medium and conditions, we found that glycerol, glucose, fatty acids, potassium acetate, temperature, and initial pH are important for producing (2S)-naringenin. Using the optimum fermentation medium and conditions, our best strain, Nar-17LM1, could produce 588 mg/l (2S)-naringenin from glucose in a 5-L bioreactor, the highest titer reported to date in E. coli.

• Journal of Life Science
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• v.18 no.4
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• pp.556-564
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• 2008

Response surface methodology was used to monitor the optimization of fermentation conditions for red ginseng wine. A central composite design was applied to investigate the effects of independent variables, fermentation temperature ($X_1$), fermentation time ($X_2$) and initial pH ($X_3$) on dependent variables, physicochemical characteristics and effective ingredients. Alcohol and total sugar content were significantly affected both by fermentation temperature and time. Crude saponin content was greatly affected by fermentation time, and pH was significantly affected by initial pH. Fermentation time and initial pH had a greater effect on ginsenoside content than fermentation temperature. Ginsenoside content increased along with fermentation time and initial pH. We elicited a regression formula for each variable, and superimposed the total optimum points of fermentation conditions for physicochemical characteristics and the effective constituents. The predicted values at the optimum fermentation conditions were at $21{\sim}27^{\circ}C$ for $15{\sim}20$ day in initial pH $4.6{\sim}5.2$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.8
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• pp.492-501
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• 2016

This study was conducted to investigate the physiochemical characteristics of Cheongju prepared using different types of rice (rice and glutinous rice) according to addition rate of Nuruk during low temperature fermentation. The characteristics of Cheongju prepared using three different temperatures ($10^{\circ}C$, $18^{\circ}C$, $25^{\circ}C$) were compared. After fermentation for 30-50 days, the pH of mash prepared at lower temperature was lower, as was that of mash made from rice relative to that prepared using glutinous rice. The total acidity was formed at lower temperature and generated in mashing prepared by glutinous rice. The organic acid content of mash made from rice at $18^{\circ}C$ was lowest, while that of mash prepared from glutinous rice was lowest at $10^{\circ}C$. The fermentation speed was lowest at $10^{\circ}C$; however, low temperature fermentation resulted in the highest alcohol content. The mash prepared from glutinous rice showed faster fermentation than that made from rice. In addition, the pH was lower when lower levels of Nuruk were added and higher in mash made from glutinous rice than that prepared from rice. The lower addition rate of Nuruk also showed a lower sugar content and final alcohol content. The levels of citric acid and lactic acid were higher, while those of succinic acid, acetic acid, and ethyl acetate were lower when lower levels of Nuruk were added. The mash prepared from glutinous rice showed a higher alcohol content than that made from rice.

• Journal of Microbiology and Biotechnology
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• v.1 no.3
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• pp.202-206
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• 1991

To produce acetoin as a precursor of the tetramethylpyrazine flavor compound from citrate by Lactococcus lactis ssp. lactis biovar. diacetilactis FC1, fermentation factors such as inital pH of culture media, temperature, concentration of Na-citrate, thiamin-HC1 and sugars were examined. The best acetoin production was achieved with initial pH in the culture media of 5.5, fermentation temperature of $34^{\circ}C$, Na-citrate concentration of 3%, addition of thiamin-HC1 at 2 mg/l and galactose as a carbon source. When fermentation was carried out under the optimum conditions, the exhaustion of Na-citrate and the production of acetoin took simultaneously and acetoin reached the maximum content, 80 mmole/l after 20 hours.

• Journal of Microbiology and Biotechnology
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• v.1 no.4
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• pp.281-284
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• 1991

To investigate the optimum conditions for the production of ammonia as a precursor of tetramethylpyrazine flavor compound from arginine by Lactococcus lactis ssp. lactis biovar. diacetilactis FC1, fermentation factors such as initial pH of culture media, fermentation temperature, concentration of arginine-HC1, and sugars were examined. The optimum conditions were initial pH 5.5 of the culture media, fermentation temperature of $34^{\circ}C$, 6% (w/v) of arginine-HC1, and 1% (w/v) of galactose as a carbon source. Under the optimum fermentation conditions, 40 mmole/l of ammonia was produced after 40 h.

• Journal of the Korean Wood Science and Technology
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• v.36 no.6
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• pp.147-158
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• 2008

In this study, fermentation characteristics of waste agricultural and forest biomass for production of heat energy were focused to be used in agricultural farm households. The purpose of this study was focused on seeking practical utilization of agricultural and forest biomass wastes in agricultural farm households in the form of thermal energy by means of simple fermentation process. Fermentation process was performed in terms of different raw-materials and their mixture with different ratios. Urea, lime, and bioaids were added as fermenting aids. Moisture contents of fermenting substrates were adjusted to 55~65%. In order to optimize the fermentation process various factors, such as raw-materials, moisture contents, amount of fermenting aids, and practical measurement of hot-water temperature during fermentation were carefully investigated. The optimum condition of fermenting process were obtained from hardwood only and hardwood: softwood (50 : 50) beds. In case of hardwood only the highest temperature was recorded between 60 to $90^{\circ}C$ the lowest temperature was determined to more or less $40^{\circ}C$ and the average temperature was ranged to $50{\sim}60^{\circ}C$ and this temperature ranges were maintained up to 20~30 days. The optimum amount of additives were estimated to ca. 15 kg of urea, 20 kg of bioaids, and 10 kg of lime for 1 ton of substrate. To reach the highest temperature the optimum moisture content of fermenting substrate was proved to 55% among three moisture content treatments of 45%, 55% and 65%. The temperature of hot-water tank installed in fermenting bed of hardwood : grass (50 : 50) showed very different patterns according to measuring positions. In general, temperatures in the mid- and upper-parts of substrate piling were relative higher than lower and surface parts during 45-day fermentation process. The maximum temperature of fermenting stage was determined to $65^{\circ}C$, minimum temperature, more or less $40^{\circ}C$, and average temperature was $60^{\circ}C$. The water temperature of tank exit was ranged to $33{\sim}48^{\circ}C$ during whole measuring periods. It could be concluded that fermentation process of waste agricultural and forest biomass produces a considerable amounts of heat, averaging about $50{\sim}60^{\circ}C$ for maximum 3 months by using the heat exchanger (HX-helical type).