• Korean Journal of Agricultural Science
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• v.35 no.1
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• pp.1-9
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• 2008

There were four types of Doenjang fermentation as following conditions for investigation ; 1) low temperature fermentation at $13^{\circ}C$ for 180 days, 2) low temperature at $13^{\circ}C$ for 7 days to room temperature at $30^{\circ}C$ for 10 days, to low temperature at $13^{\circ}C$ for 163 days, and for 173 days, 3) low temperature at $13^{\circ}C$ 7 days to room temperature at $30^{\circ}C$, 4) room temperature at $30^{\circ}C$ for 180 days. There were no changes of moisture, NaCl and total nitrogen content during fermentation period of four types conditions, but pH and amino type nitrogen decreased in room temperature at $30^{\circ}C$ for 180 days. It required 3 times more fermentation period until same quantity of the amino type nitrogen. The low temperature fermentation sample was lower than room temperature fermentation sample in pH and amino type nitrogen. The yeast decreased in low temperature fermentation sample taken 15 to 30 days longer than room temperature sample. The yeast is increased up to 30 days, and decreased little by little. After 60 days, it remained a few without effectiveness on the Doenjang quality. The low temperature fermentation sample showed brighter than room temperature fermentation sample. Different fermentation condition affected Doenjnag quality, especially, low temperature fermentation sample showed bright color in Doenjnag. So low temperature fermentation must be expected as good method for getting high quality Doenjnag.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.1
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• pp.16-23
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• 1998

Effect of Fermentation temperature on the changes of chemical components in Kakudgi during fermentation was investigated by measuring free sugar, organic acid and volatile compounds up to 57 days at several temperatures. The mannitol was increased in palatable period in contrast with those of other free sugars. The higher the initial fermentation temperature was and the longer the initial fermentation time at 2$0^{\circ}C$ was, the faster the second increasing period was and the less the initial contents was. Lactic acid was increased 6~31 times from a little amount at the initial period. The higher the initial fermentation temperature was and the more the increasing content was. But malic acid which was abundant(55.1% of total nonvolatile organic acid) in the initial fermentation period was remarkably decreased in the palatable period. The change of the sulfides among the volatile compounds was remarkable. Methyl allyl sulfide which was a little in the initial fermentation period was remarkably increased in the final fermentation period, and the correlation coefficients between the content of methyl allyl sulfide and aroma in sensory evaluation were high. It could be suggested that the fermentation temperature should be set to 4$^{\circ}C$ after fermentating at 2$0^{\circ}C$ for 36 hours in the view point of keeping the Kakdugi taste and quality well because of high content of free sugar and nonvolatile organic acids.

• Journal of Fisheries and Marine Sciences Education
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• v.24 no.6
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• pp.755-762
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• 2012

Qualities properties of fish sauce made jack mackerel (Trachurns japonicus) at different salt concentrations (25~35%) for 240 days at fermentation temperature ($25{\sim}55^{\circ}C$) were investigated. Total nitrogen content of the fish sauce made jack mackerel at 25% salt concentration after 240 day of fermentation was higher than those of 30%, 35% salt concentration. Total nitrogen content was increased under the same condition as fermentation temperature increased except at $55^{\circ}C$. Amino nitrogen contents at 25% salt concentration after 240 day of fermentation at 35, 45, $55^{\circ}C$ were 949.3, 812.8 and 834.4 mg/100 g, respectively. Those at 25, $55^{\circ}C$ fermentation temperature were 811.2 and 614.8 mg/100 g, respectively. The amino acid nitrogen content at 30 and 35% salt concentration ware lower than 20% salt concentration and that after 240 day of fermentation at $55^{\circ}C$ was lowest. The volatile basic nitrogen content increased during fermentation as fermentation temperature increased. However, increasing salt concentration controlled the formation of volatile basic nitrogen. Histamine content of samples fermented at $25{\sim}55^{\circ}C$ after 240 days were 9~20 mg/kg showing that it was not significantly different among salt concentration. The results indicated that the controlled salt concentration and fermentation temperature could be used as a successful process for fish sauce of jack mackerel as an unused resource.

• Korean Journal of Human Ecology
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• v.5 no.1
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• pp.48-61
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• 2002

This study was carried out to investigate the effects of four kinds of leavening agents on Jeung-Pyun fermantation. Milk-wine(M), fresh yeast(F), dry yeast(D), instant yeast(I) were used in Jeung-Pyun ingredients. The physicochemical properties, sensory evaluation were examined. The results of this study are summarized as follows: 1. Basic recipes for Jeung-Pyun by preliminary test were developed. 2. Specific volumes and expansion ratio of Jeung-Pyun was higher in the fresh yeast-added sample. 3. The pH of Jeung-Pyun was decreased significantly as the fermentation progressed 4. In the result comparing Jeung-Pyun extracting after 1st fermentation with Jeung-Pyun extracting 2nd fermentation by SEM, the former was widely distributed in stability of bubble and pore than the latter. 5. Standard recipe by Q.D.A. test added four kinds of leavening agents were as follows: (1)Jeung-Pyun added milk wine was 240min for 1st fermentation time, 60min for 2nd fermentation time, 35$^{\circ}C$ for fermentation temperature, 80% for fermentation humidity respectively. (2) Jeung-Pyun added fresh yeast was 90min for 1st fermentation time, 40min for 2nd fermentation time, 35$^{\circ}C$ for fermentation temperature, 80% for fermentation humidity respectively. (3)Jeung-Pyun added dry yeast was 90min for 1st fermentation time, 60min for 2nd fermentation time, 35$^{\circ}C$ for fermentation temperature, 60% for fermentation humidity respectively. (4)Jeung-Pyun added instant yeast was 90min for 1st fermentation time, 40min for 2nd fermentation time, 30$^{\circ}C$ for fermentation temperature, 60% for fermentation humidity respectively. 6.Based on sensory evaluation, Jeung-Pyun added fresh yeast was significantry higher than others in color, sweetness, moistness, softness, and overall quality. There was negative significance between milk wine flavor and astrigentness, and yeast flavor.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.4
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• pp.467-475
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• 2007

This study was conducted to examine temperature effects on hydrogen production in anaerobic fermentation. 18 batch reactors were operated at mesophilic ($35^{\circ}C$) and thermophilic conditions ($55^{\circ}C$) to achieve maximum hydrogen production in anaerobic fermentation. Optimum hydrogen production conditions were also investigated at each temperature. Different trends were observed regarding pH effects on hydrogen production. This effect was not significant for mesophilic fermentation ($35^{\circ}C$). In this case, pH may not drop to interfere hydrogen production during the test. However, hydrogen production decreased without pH control for thermophilic condition ($55^{\circ}C$). Effects of heat treatment were observed for both fermentation process. Hydrogen production with heat treatment was higher than hydrogen production without heat treatment for both fermentation processes. The amount of produced hydrogen for each substrate concentration with temperature changes showed that more hydrogen was produced at $35^{\circ}C$ than at $55^{\circ}C$.

• Journal of Microbiology and Biotechnology
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• v.34 no.4
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• pp.863-870
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• 2024

Meju, a fermented soybean brick, is a key component in soybean foods like doenjang and ganjang, harboring a variety of microorganisms, including bacteria and fungi. These microorganisms significantly contribute to the nutritional and sensory characteristics of doenjang and ganjang. Amplicon-based next-generation sequencing was applied to investigate how the microbial communities of meju fermented at low and high temperatures differ and how this variation affects the microbial communities of doenjang, a subsequently fermented soybean food. Our metagenomic data showed distinct patterns depending on the fermentation temperature. The microbial abundance in the bacterial community was increased under both temperatures during the fermentation of meju and doenjang. Weissella was the most abundant genus before the fermentation of meju, however, it was replaced by Bacillus at high temperature-fermented meju and lactic acid bacteria such as Weissella and Latilactobacillus at low temperature-fermented meju. Leuconostoc, Logiolactobacillus, and Tetragenococcus gradually took over the dominant role during the fermentation process of doenjang, replacing the previous dominant microorganisms. Mucor was dominant in the fungal community before and after meju fermentation, whereas Debaryomyces was dominant under both temperatures during doenjang fermentation. The dominant fungal genus of doenjang was not affected regardless of the fermentation temperature of meju. Strong correlations were shown for specific bacteria and fungi linked to specific fermentation temperatures. This study helps our understanding of meju fermentation process at different fermentation temperatures and highlights different bacteria and fungi associated with specific fermentation periods which may influence the nutritional and organoleptic properties of the final fermented soybean foods doenjang.

• Korean Journal of Microbiology
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• v.20 no.2
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• pp.67-72
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• 1982

The effect of fermentation temperature on the production of high content alcohol has been investigated with high substrate concentration. The maximum specific growth rate, ${\mu}max\;was\;0.461hr^{-1}\;at\;35^{\circ}C$ which was the highest, whereas the maximum biomass concentration waas 8.7g/l at $25^{\circ}C$, at the growth rate lower than at $35^{\circ}C$. Approximately 140g/l of ethanol was produced in the temperature range of 20 to $25^{\circ}C$ with nearly complete comsumption of the substrate. Extended fermentation time has been required at lower temperatures, however, for the maximum values of biomass concentration and alcohol content, hence higher ethanol productivity, as the temperature was elevated to $40^{\circ}C$. The viability of yeasts was greatly improved by lowering the fermentation temperature down to $25^{\circ}C$ and also extended survival of the cells has been observed at lower fermentation temperatures, although the ethanol concentration of both waas higher.

• Microbiology and Biotechnology Letters
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• v.17 no.6
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• pp.619-623
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• 1989

The effects of temperature on yeast growth and ethanol production were investigated in batch cultures. The maximum specific growth rate of yeast was obtained at 36$^{\circ}C$ and the maximum specific production rate of ethanol was obtained at 33$^{\circ}C$. A mathematical model was employed to describe the temperature effects in ethanol fermentation and the parameters in the model were expressed as a function of temperature. Optimum temperature control strategy, from the simulation result, consists of starting the fermentation at high temperature and lowering the temperature as the fermentation proceeds.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.4
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• pp.773-779
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• 1999

This study was conducted to determine the changes in the contents of vitamin C and fermentation characteristics of kimchi on different Chinese cabbage variety(Koreangji Yureum: KY, Kalak Shin Il Ho: KS) and fermentation temperature(5oC, 15oC). Kimchi were fermented at 5oC and 15oC for 140 days and 25 days respectively. In all samples, total acidity increased, and the pH, total sugar and reducing sugar content decreased as the fermentation proceeded. Also, the number of lactic acid bacteria reached the maximum at the optimum fermenting stage. On the other hand, total ascorbic acid, dehydroascorbic acid and ascorbic acid from individual kimchi solid tissue significantly decreased with fermentation periods, however, increased kimchi liquid at the 7day in KS 15(kimchi prepared with Kalak Shin Il Ho at 15oC), KY 15(kimchi prepared with Korangji Yureum at 15oC) and at the 65day in KY 5(kimchi prepared with Korangji Yureum at 5oC) respectively. Therefore, different fermentation temperature as well as variety affected ascorbic acid contents and chemical characteristics of kimchi.

• Journal of Microbiology and Biotechnology
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• v.4 no.4
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• pp.316-321
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• 1994

We investigated the possibility of industrial application and economit process of high temperature fermentation by thermotolerant alcohol producing yeasts as previously reported. From the 20% glucose media, the RA-74-2 produced 11.8% (v/v) ethanol at $32^{\circ}C$ (0.5% inoculum) and 10.6% (v/v) ethanol at $40^{\circ}C$ (3% inoculum), respectively. Also, 11.3% (v/v) ethanol was produced for 96 hours in the temperature-gradient fermentation. These results suggest that the RA-74-2 could isuccessfully be applied to save the cooling water and energy in industrial scale without re-investment or modification of established fermentation systems. When potato starch was used as the substrate for the RA-74-2, high temperature fermentation above $40^{\circ}C$ was more appropriate for industrial utilization because organic nitrogen was not necessary to economical fermentation. As the naked barley media just prior to industrial inoculation, taken from the Poongkuk alcohol industry Co., were used, 9.6% (v/v) ethanol was produced at $40^{\circ}C$ for 48 hours in jar-fermentor scale (actually, 9.5-9.8% (v/v) ethanol was produced at 30~$32^{\circ}C$ for 100 hours in industrial scale). The ethanol productivity was increased by the high glucoamylase activity as well as the high metabolic ratio at $40^{\circ}C$ Therefore, if the thermotolerant yeast RA-74-2 would be used in industrial scale, we could obtain a high productivity and saving of the cooling water and energy. Meanwhile, the RA-912 produced 6%(v/v) ethanol in 10% glucose media at $45^{\circ}C$ and showed the less ethanol-tolerance compared with industrial strains. As the produced alcohol was recovered by the vacuum evaporator at $45^{\circ}C$ in 15% glucose media, the final fermentation ratio was enhanced (76% of theoretical yields). This suggest that a hyperproductive process could be achieved by a continuous input of the substrate and continuous recovery of the product under vacuum in high cell-density culture.