• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.3
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• pp.405-410
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• 2002

The optimum conditions of the alcohol fermentation with raw tapioca by simultaneous saccharification and alcohol fermentation (SSAF) were studied using raw starch enzyme. The optimum conditions for maximum alcohol production were 0.5% (w/w) of enzyme content, 250% (v/w) of added water content and 96 hr of fermentation time. The alcohol and reducing sugar contents were 11.7% and 306 mg% after 96 hr fermentation, respectively. During the fermentation pH decreased from 6.2 to 4.2 and total acidity increased from 0.11 to 0.43. Alcohol components were detected such as ethanol, methanol, iso-propanol, n-propylalcohol and iso-butylalcohol, besides acetaldehyde. We could construct raw starch fermentation conditions which was 250% (v/w) of added water content and 0.5% (w/w) of enzyme content. However, yield of raw starch alcohol fermentation was lower than that of steaming alcohol fermentation.

• Journal of Korean Medicine for Obesity Research
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• v.18 no.2
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• pp.64-73
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• 2018

Objectives: This study investigated the effect on microbial ecology, fermentation characteristics and anti-obesity of Platycodon grandiflorum (PG) fermentation with salt. Methods: PG was fermented for four weeks with 2.5% salt and the characteristics of fermented PG were performed by measuring pH, total sugar content, viable bacteria number and microbial profiling. Also, we measured total polyphenol, flavonoid and the percent of inhibition of lipase activity and lipid accumulation. Results: Salt added to PG for fermentation had an effect on pH, total sugar, total and the number of lactic acid bacteria. Total sugar and pH were reduced and number of total and lactic acid bacteria were increased after fermentation. The majority of bacteria for fermentation were Lactobacillus plantarum, Leuconostoc psedomesenteroides and Lactococcus lactis subspecies lactis regardless of salt addition. However, microbial compositions were altered by added salt and additional bacteria including Weissella koreensis, W. viridescens, Lactobacillus sakei and Lactobacillus cuvatus were found in fermented PG with salt. Total flavonoid was increased in fermented PG and lipid accumulation on HepG2 cells treated with fermented PG was reduced regardless of salt addition. Moreover, fermented PG without salt suppressed lipase activity. Conclusions: Addition of salt for PG fermentation had influence on fermentation characteristics including pH and sugar content as well as number of bacteria and microbial composition. In addition, fermented PG showed anti-obesity effect by increasing flavonoid content and inhibition of lipase activity and lipid accumulation.

• Journal of Life Science
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• v.32 no.2
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• pp.119-124
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• 2022

To effectively isolate acetic acid bacteria for producing makgeolli vinegar, various products were researched, and Acetobacter pasteurianus CK-1, a strain that is excellent in acetic acid production, was finally isolated. The optimal growth temperature of the isolated strain was confirmed to be 30℃, and it grew well in the pH range of 5.5~6.5, with optimal growth at pH 6. A. pasteurianus CK-1 had the most active proliferation when the initial ethanol concentration in the medium was 4%, and growth was possible even at an ethanol concentration of 7%. When inoculating the isolated strain into makgeolli to induce acetic acid fermentation, the pH at the beginning of fermentation was 3.54, which was gradually lowered to 2.77 after 18 days of fermentation. The acidity was 0.75% at the beginning of fermentation and gradually started to increase from the 4th day of fermentation. The final acidity at the end of fermentation was 5.54%. In the vinegar fermented by inoculating A. pasteurianus CK-1, acetic acid content was detected to be as high as 3,575.7±48.6 mg%, and the malic acid and citric acid contents were 2,150.8±27.6 and 55.8±3.7 mg%, respectively. Further, it was confirmed that the content and ratio of the organic acids produced significantly differed depending on the type of inoculated bacterial strain. During acetic acid fermentation, the populations of yeast and A. pasteurianus CK-1 were inversely changed. In the initial stage of fermentation, yeast dominated, and after 10 days of fermentation, A. pasteurianus CK-1 slowly proliferated and reached stationary phase.

• Journal of Sensor Science and Technology
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• v.18 no.1
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• pp.72-76
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• 2009

The sensing system was designed and fabricated to investigate the ferment environment of soybeans. $NH_3$ gas was saturated after about 7 h and $CO_2$ gas was reached the peak after about 8 h in the inoculation of Bacillus subtilis. However, times that $CO_2$ gas and $NH_3$ gas were reached maximum value without Bacillus subtilis were about 15 h and 18 h, respectively. The sample that inoculated Bacillus subtils had deeper taste than one without it. We found that the peak time of $CO_2$ gas means the starting time of fermentation. If we control the operating time after the start of fermentation, it is expected to make a suitable Chungkukjang to individual preference.

• 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 Microbiology and Biotechnology
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• v.22 no.3
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• pp.400-406
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• 2012

To improve the hydrogen yield from biological fermentation of organic wastewater, a co-culture system of dark- and photo-fermentation bacteria was investigated. In a pure-culture system of the dark-fermentation bacterium Clostridium butyricum, a pH of 6.25 was found to be optimal, resulting in a hydrogen production rate of 18.7 ml-$H_2/l/h$. On the other hand, the photosynthetic bacterium Rhodobacter sphaeroides could produce the most hydrogen at 1.81mol-$H_2/mol$-glucose at pH 7.0. The maximum specific growth rate of R. sphaeroides was determined to be 2.93 $h^{-1}$ when acetic acid was used as the carbon source, a result that was significantly higher than that obtained using either glucose or a mixture of volatile fatty acids (VFAs). Acetic acid best supported R. sphaeroides cell growth but not hydrogen production. In the co-culture system with glucose, hydrogen could be steadily produced without any lag phase. There were distinguishable inflection points in a plot of accumulated hydrogen over time, resulting from the dynamic production or consumption of VFAs by the interaction between the dark- and photo-fermentation bacteria. Lastly, the hydrogen production rate of a repeated fed-batch run was 15.9 ml-$H_2/l/h$, which was achievable in a sustainable manner.

• Microbiology and Biotechnology Letters
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• v.20 no.2
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• pp.203-206
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• 1992

Conditions of fermentation for the production of demethyltetracycline were examined using the mutant, which was obtained through the cell fusion of demeclocycline producing strains, The optimum temperature and the initial pH of broth for demethyltetracycline fermentation were $25^{\circ}C$ and 6.7, respectively. Unlike any other cases, the control of pH with alkali solution during the fermentation process affected the productivity. As a general rule, the larger the inoculum size the higher the early consumption of sugar and the viscosity of broth, which means that fermentation proceeds more rapidly as the inoculum size is increased. The highest productivity was shown when the inoculum size was 5% (v/v), and the phase of seed also influenced the fermentation. Among the parameters of pre-culture thus examined, pH was the most important factor.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.3
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• pp.11-17
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• 2015

In acid hydrolysis process of biomass saccharification. neutralization of acid hydrolyzate is essential step, which resulted in dissolved cations in glucose solution. Impact of cations to Kluyveromyces marxianus in glucose solution was investigated focused on ethanol fermentation. Either potassium or sodium cations decreased the ethanol fermentation and glucose to ethanol conversion. Glucose consumption by K. marxianus was delayed by increasing potassium cation concentration as completely consumed within 12 h in potassium cation 0.46 mol and 0.92 mol but within 24 h in potassium cation 1.38 mol. Also, ethanol fermentation process was slowed down with increasing concentration of the potassium sulfate. Fermentation of glucose solution to ethanol was more inhibited by sodium cation than potassium cation in glucose solution. Glucose was completely consumed within 24 h in sodium cation 0.95 mol. but at 1.90 mol or 2.84 mol in sodium cation could not finish the fermentation within 48 hour. Ethanol concentration was 22.26 g/L at low sodium cation in glucose solution with complete fermentation within 24 h. With increasing sodium cation in glucose solution, final ethanol concentration was reached at 14.10 g/L (sodium cation con) and 0.21 g/L (sodium cation con), which meant delaying of fermentation by sodium cations.

• Korean journal of food and cookery science
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• v.19 no.4
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• pp.504-510
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• 2003

To optimize the preparation process of Jeung-Pyun, an experiment was derived, using a central composite design, to fmd the optimal mixing conditions. The addition of Paecilomyces japonica powder, the volume of Tak-Ju and the second fermentation time were independent variables, with the pH, volume, color, sensory and texture properties of the Jeung-Pyun selected as response variables. As the Paecilomyces japonica powder and fermentation time were increased, the b values and volume after the second fermentation also increased. The color of the Jeung-Pyun became deeper with increases in the Paecilomyces japonica powder and fermentation time, and was deepest on the addition of 30% Tak-Ju. The pH increased with increasing fermentation time of the Jeung-Pyun, and on the addition of 3% Paecilomyces japonica rapidly increased more than with the other groups. The optimal mixing conditions for the best quality Jeung-Pyun, with restricted conditions above a b value of 3, a color intensity above 3, and a volume of 40mQ and a pH of 4.02-4.04 after the second fermentation, were 4.0%, 20% and 45 mins for the Paecilomyces japonica powder, Tak-Ju and second fermentation time, respectively.

• Food Science and Preservation
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• v.5 no.4
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• pp.374-379
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• 1998

A vinegar was prepared from uncleaned rice by two step fermentation, alcohol fermentation followed by acetic acid fermentation. The contents of alcohol reached to 10.8% during the alcohol fermentation of uncleaned rice with nuruk, and acidity reached to 5.78% during the acetic acid fermentation. Acidity and pH of vinegar of two step fermentation were higher than those of commercial vinegars. 'L' value(Light) of the vinegar was lower, 'a' and 'b' value were higher than those of commercial vinegars. The contents of acetic acid, malic acid, citirc acid and tartaric acid were hish in organic acid of vinegars. The content of each ofganic acid in vinegars was remarkably different. The content of free amino acids was 2199.7${\mu}\ell$/ml in the vinegar produced by two step fermentation which is higher than that of others.