• Journal of Microbiology and Biotechnology
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• v.21 no.5
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• pp.519-524
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• 2011

The correlation between alcoholic fermentation rate, measured as carbon dioxide ($CO_2$) evolution, and the rate of hydrogen sulfide ($H_2S$) formation during wine production was investigated. Both rates and the resulting concentration peaks in fermentor headspace $H_2S$ were directly impacted by yeast assimilable nitrogenous compounds in the grape juice. A series of model fermentations was conducted in temperature-controlled and stirred fermentors using a complex model juice with defined concentrations of ammonium ions and/or amino acids. The fermentation rate was measured indirectly by noting the weight loss of the fermentor; $H_2S$ was quantitatively trapped in realtime using a pre-calibrated $H_2S$ detection tube which was inserted into a fermentor gas relief port. Evolution rates for $CO_2$ and $H_2S$ as well as the relative ratios between them were calculated. These fermentations confirmed that total sulfide formation was strongly yeast strain-dependent, and high concentrations of yeast assimilable nitrogen did not necessarily protect against elevated $H_2S$ formation. High initial concentrations of ammonium ions via addition of diammonium phosphate (DAP) caused a higher evolution of $H_2S$ when compared with a non-supplemented but nondeficient juice. It was observed that the excess availability of a certain yeast assimilable amino acid, arginine, could result in a more sustained $CO_2$ production rate throughout the wine fermentation. The contribution of yeast assimilable amino acids from conventional commercial yeast foods to lowering of the $H_2S$ formation was marginal.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.6
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• pp.812-817
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• 2003

In the first stage, strawberry wine was manufactured in 14$^{\circ}$Brix initial sugar content, for 50 hr at 28$^{\circ}C$ using Saccharomyces kluyeri DJ97. In the second stage, the acetic acid fermentation conditions for maximun acidity (4.60%) were 1.48% initial acidity and 195.76 rpm in agitation rate for 7.34 day. The fermentation conditions for maximun Hunter color a value were 1.78% initial acidity and 117.63 rpm in agitation rate for 7.35 day. Therefore, optimum acetic acid fermentation conditions were 1.5% initial acidity and 196 rpm in agitation rate for 176 hr using Acetobacter sp. PA97.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.1
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• pp.15-21
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• 2004

The purpose of this research was to investigate loading rate of influent for acidogenic fermentation. Laboratory batch experiments were conducted, at $35^{\circ}C$, HRT 18hr, pH 6 and used 3.5L reactor. Loading rate of influent was varied 2.0 to 4.0g VSS/L, TOA concentration is decreased according to increasing loading rate Over 2.5g VSS/L. When loading rate is 2.0g VSS/L, hydrolysis percentage show the maximum value of 87%. Most of SCFA is consist of HAc, HPr, I-HBu and MBu. HAc concentration is 5,233mg/L in the 2.0g VSS/L condition. So, for this study, we think that limiting loading rate is 2.5g VSS/L. SCFA species was investigated to HAc, HPr, I-HBu and n-HBu during our studying. HAc/SCFA ratio is about 89.3%, SCFA production rate is highest to $1,104mg\;COD/L/d{\cdot}gPCOD$ for 2.0g VSS/L loading rate.

• Microbiology and Biotechnology Letters
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• v.20 no.5
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• pp.588-596
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• 1992

The fermentation characteristics of ethanol production by the use of immobilized Zymomonas mobilis KCTC 1534 cells were investigated in terms of formation factors such as substrate and product concentration. In batch fermentation, the maximum values of specific ethanol productivity, specific substrate uptake rate, ethanol yield, and glucose conversion rate were $29.14g/{\ell}{\cdot}h$, $60.24g/{\ell}{\cdot}h$, 0.48g/g, and 98.4%, respectively, with 17% glucose medium, and its ethanol productivity was $2.91g/{\ell}{\cdot}h$ in the case of 25 hour fermentation time. Repeated batch fermentation was possible for 30 days with 2.24-$2.94g/{\ell}{\cdot}h$ ethanol productivity. In semicontinuous fermentation, the maximum ethanol productivity was shown to be $15.7g/{\ell}{\cdot}h$ at $0.36h^{-1}$ effective dilution rate with 17% glucose concentration. In this case, ethanol yield coefficient and glucose conversion rate were 0.39 g/g, 64.7%, respectively.

• Applied Biological Chemistry
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• v.34 no.3
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• pp.235-241
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• 1991

Several spices in the range of $1{\sim}3%\;(w/w)$ were added during Kimchi preparation in order to investigate their effects on the chemical changes and fermentation rate. The results showed that addition of red pepper powder by 2% slightly increased the fermentation rate reaching max. value after 36 hours, while 3% addition gradually increased its rate without max. point. Generally higher reducing sugar and acidity were measured for red pepper added Kimchi. The fermentation rate and its max. point were significantly increased as more garlic added and the max. value of ascorbic acid produced was also increased. Little effects were found for Welsh onion and ginger on Kimchi fermentation.

• Korean Journal of Food Science and Technology
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• v.35 no.4
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• pp.642-647
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• 2003

In order to investigate utilization possibility of persimmon peel as a source of vinegar, we had been examined the alcohol and acetic acid fermentations of persimmon peel. In the first stage, alcohol fermentation, alcohol content was maximum value (8.22%) in 12.43 mL/g of added water, $12.41^{\circ}Brix$ of initial sugar content and 48.05 hr of fermentation time. Acidity was minimum value (0.30%) in 12.18 mL/g of added water, $13.72^{\circ}Brix$ of initial sugar content and 46.22 hr of fermentation time. In the second stage, acetic acid fermentation, acidity was maximum value (6.40%) in 2.02% of initial acidity, 67.98 rpm of agitation rate and 6.94 day of fermentation time. Browning color was minimum value in 1.50% of initial acidity, 150.0 rpm of agitation rate and 6.0 day of fermentation time. To manufacture persimmon vinegar using persimmon peel, in the first stage, optimal alcohol fermentation conditions was 12mL/g in added water, $12^{\circ}Brix$ in initial sugar concentration and 48 hr in fermentation time. In the second stage, optimal acetic acid fermentation conditions was 1.8% in initial acidity, 70 rpm in agitation rate and 6 day in fermentation time using Acetobacter sp. PA97.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.5
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• pp.807-813
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• 1997

Various additives(glucono-$\delta$-lactone, glycine, chitosan, Chinese pepper extract+msutard oil, cinnamon oil+ginger oil+mustard oil, Chinese pepper extract), used in the Korean patents singularly or in combination, were tested for extension of shelf-life of kimchi. Addition of glucono-$\delta$-lactone or chitosan was somewhat effective in delaying the fermentation rate, however no such effect was seen by other additives. Chitosan at the concentrations of 0.5, 1.0, and 1.5% was similarily effective in delaying the fermen-tation rate. Mustard oil or cinnamon oil tend to delay the fermentation rate by singular addition at the concern tration of 0.5% or 1%. Soaking of the salted and washed Chinese cabbage in 0.5% chitosan solution resulted in delay of the fermentation rate of kimchi.

• Journal of Animal Environmental Science
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• v.18 no.3
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• pp.137-144
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• 2012

This study was conducted to determine the effect of feed additives including probiotics, moisture and feed ingredients and the effect of fermented feed on digestibility and volatile fatty acid (VFA) level in finishing pigs. Feed was mixed with microbials including Saccharomyces, Lactobacillus, Enterococcus and Pediococcus together with different levels of probiotics, 0.25, 0.5, 1, 2, 3%. Addition of probiotics showed improved fermentation rate after 48 h incubation. To determine the optimal moisture level for fermentation, different levels of water, 30, 40, 50 and 60%, were added into the feed. Fermentation rate of feed with 40~50% moisture level was higher than that from 60% level at 60 h post-fermentation. In vitro fermentation rate of feed ingredients was analyzed by comparing VFA levels. Beet pulp and tapioca showed higher fermentation rate compare to other ingredients including canola meal or rapeseed meal. To determine the effect of administration of fermented feed In vivo, feces from finishing pigs were analyzed. Finishing pigs administrated with fermented feed showed improved digestibility and higher volatile fatty acid (VFA) level. In conclusion, results from the current study indicate that 40~50% of moisture with addition of beet pulp and tapioca in feed is optimal condition for fermentation. Furthermore, our data suggest that fermentation of feed can improve the feed quality and digestibility, thereby provide more nutrient in finishing pigs.

• Microbiology and Biotechnology Letters
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• v.23 no.4
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• pp.479-484
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• 1995

The effect of initial cell concentration on the characteristics of ethanol fermentation was investigated in the batch fermentation of Saccharomyces cerevisiae ATCC 24858. The characteristics were investigated in the range of 60 to 230 g/l of the initial sugar concentrations and 0.5 to 85 g/l of the initial cell concentrations. When the initial cell concentrations were 27 g/l for 60 g/l of the initial sugar and 85 g/l for 230 g/l, the fermentation time required for the complete consumption of the initial sugar was one hour, respectively. The ethanol productivity increased with the initial cell concentration so that, in the case of 100 g/l of initial sugar, the productivity rose up to 55 g/l/hr at 55 g/l of the initial cell concentration. The specific growth rate decreased according to the increase in the initial biomass concentration and finally became zero at around 25 g/l of the cell concentration regardless of the initial sugar concentration. The specific ethanol production rate was constant as 1.02 g/l/hr up to 150 g/l of the initial sugar. However, the rates decreased sharply with the augmentation of concentration of the initial sugar above 160 g/l. The overall ethanol yield represented a constant value, 0.475 g/g irrespective of the initial cell and sugar concentrations. The overall biomass yietd showed a trend to diminish in values with the biomass and ultimately to reach zero more than 25 g/l of the initial cell concentration.

• The Korean Journal of Community Living Science
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• v.26 no.1
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• pp.127-133
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• 2015

This study identifies the factors improving bread quality by using fermented liquid dough. Fermented liquid dough, the main part of bread dough, contains yeasts that are prepared in order to enhance the fermentation rate. This study investigates the fermentation rate after mixing dough, the pH of dough, loaf volume, water activity, hardness, and sensory properties of loaf bread samples with different amounts of fermented liquid dough. The fermentation rate was slightly higher in the bread samples, the control dough and 10% fermented liquid dough, than in samples with more than 20% dough. The pH values of dough decreased with an increase in the content of fermented liquid dough. The loaf volume of bread with 10% fermented liquid dough was the highest. The water activity of loaf bread increased with an increase in amount of fermented liquid dough. For the sensory evaluation of loaf bread, adding 10% fermented liquid dough improved the loaf volume and evenness of baking. These results suggest that 10% fermented liquid dough increased the fermentation rate and bread quality. Further research is required to enhance internal quality characteristics of loaf bread, including taste and flavor.