• The Korean Journal of Food And Nutrition
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• v.6 no.4
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• pp.287-293
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• 1993

This study was carried out to investigate the influences of cultural conditions of koji on the production of organic acid during rice-koji making by Aspergillus awamori var. kawachii which is now widely used as koji-mold in brewing Takju and Yakju in Korea. The optimum temperature for the germination of the conidia of the mold was 35'8, and the time required for germination at this temperature was 8 hours. Rapid germination occurred when the water content of steamed rice was above 40%, but germination retardation occurred markedly below 35%. The optimum cultural temperature for the production of organic acid was 32$^{\circ}C$, and the production of organic acid was markedly restricted at 36$^{\circ}C$ and 4$0^{\circ}C$. It was effective for the high production of both saccharogenic amylase and organic acid to shift the cultural temperature from initial 36$^{\circ}C$ to 32$^{\circ}C$ after 20~25 hours of cultivation. Initial water content suitable to the production of organic acid was 40% in steamed rice, but its production was markedly restricted below 30% of water content. When the quantity of conidial inoculation was too small, the production of organic acid was low in initial phase, but it was retrived at later period. Acid production was markedly restricted together with the increase in koji thickness.

• Microbiology and Biotechnology Letters
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• v.22 no.2
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• pp.120-125
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• 1994

By using a synthetic medium simulated on the amino acid composition of soybeam, the effect of salt concentrations on the production of volatile organic acid by the strains of Zygosaccharomyces rouxii So-3101, a soy sauce yeast, was studied at the concentrations of 12.5, 18.0, 22.0 and 28.5% NaCl. The growth, consumption of glucose, and production of alcohol, total acid and volatile organic acid, showed the highest values at a concentration of 12.5% NaCl, and those values were decreased with an increase in the salt concentration. The ratio of volatile organic acid to total organic acid was remained at approximately the same level within the range of salt concentrations between 12.5~22.0%, whereas the ratio was decreased at a salt concentration of 28.5%. After incubation for 16 days, 8 volatile organic acids, i.e. acetic, propionic, n-butyric, isobutyric, isovaleric, isocaproic, n-caproic, and heptanoic acids, were detected by gas chromatography. Among the volatile organic acids, acetic acid was produced in the appreciable amiunt and its ratio to the other volatile acids was increased with an increase in the salt concentration.A small amount of isocaproic, propionic, isobutyric and isovaleric acids were produced, and n-caproic, n-butyric and heptanoic acids were detected only at the lower salt concentration.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.9
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• pp.1255-1259
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• 2004

The objective of this study was to evaluate the effects of halogenated compounds, organic acids, unsaturated fatty acids and their mixtures on in vitro methane production and fermentative characteristics of mixed rumen microorganisms. Agents used in two in vitro experiments were bromoethanesulfonic acid (BES) and pyromellitic diimide (PMDI) as halogenated compound, fumarate and malate as organic acid, and linoleic acid and linolenic acid as unsaturated fatty acid sources. Ruminal fluid collected from a Holstein steer fed tall fescue and concentrate mixtures was incubated at $39^{\circ}C$ for 48 h with addition of those materials. Single supplementation of halogenated compounds, organic acids or unsaturated fatty acids decreased in vitro methane production (p<0.05). The second experiment was designed to investigate effects of combination of one of halogenated compounds and either organic acids or fatty acids on methane production. Lower concentration of methane and lower A:P ratio were observed with PMDI compared with BES (p<0.01). In general medium pH, VFA, total gas and hydrogen production, and dry matter degradability were affected by addition of the same compounds. In addition, PMDI+malate treatment resulted in the highest molar proportion of propionate, and lowest A:P ratio and methane production (p<0.01). Hydrogen production was highest in PMDI+linolenic acid and lowest in BES+malate treatment (p<0.01). PMDI+malate combination was the most recommendable in reducing methane production without too much influence on digestibility under conditions of present studies.

• Korean Journal of Organic Agriculture
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• v.25 no.2
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• pp.461-473
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• 2017

Total mixed ration (TMR) including concentrate diet and roughage together have been used for the ruminant animal. Relatively high concentrations of moisture and water soluble carbohydrate are representative feature of TMR. Those moisture and water can also provide a niche for bacterial growth. Therefore, a possible fermentation of TMR induced by micro-organism is generally accepted. The present study hypothesized that different lactic acid bacteria could alter fermentation of TMR and subsequently rumen fermentation. Three lactic acid bacteria, Lactobacillus paracasei (A), L. plantarum (B) and L. parabuchneri (C), were employed and 7 treatments under full factorial design were compared with control without inoculation. TMR for dairy cow was used. Significant alterations by treatments were detected at lactic acid and butyric acid contents in TMR (p<0.05). Treatment AC (mixture of A and C) and BC (mixture of B and C) showed great lactate production. Great butyrate production was found at treatment C. At in vitro rumen fermentation, treatments B, C and AB (mixture of A and B) showed significantly great total gas production (p<0.05). All treatments except treatments B and AB, showed less dry matter digestibility, significantly (p<0.05). Total volatile fatty acid production at treatment AC was significantly greater than others (p<0.05). In individual volatile fatty acid production, treatment AB and AC showed great acetate and propionate productions, significantly (p<0.05). This study investigated correlation between organic acid production in TMR and rumen volatile fatty acid production. And it was found that butyric acid in TMR had significant negative correlation with acetate, propionate, total volatile fatty acid, AP ratio and dry matter digestibility.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.9
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• pp.958-964
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• 2005

Experiment was conducted to investigate the amount of hydrogen gas and the characteristics of organic acids production from various carbohydrates by anaerobic bacteria. The variation characteristics of organic acids and hydrogen gas production at the fermentative culture were also studied in the presence of heavy metals such as cadmium or lopper. 3.43 mole hydrogen per mole of hexose was produced when sucrose was used as a carbon source. Acetic acid and butyric acid were main products by the anaerobic fermentation. Hydrogen production rate was decreased and formation of acetic acid was increased as the concentration of heavy metals was increased in the medium. The inhibition of hydrogen production by the copper was more serious than the cadmium.

• The Korean Journal of Food And Nutrition
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• v.23 no.1
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• pp.70-75
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• 2010

This study was conducted to determine the influence of culture conditions such as temperature, time, water content, koji-thickness and agitation on the production of organic acid by Rhizopus sp. ZB9 isolated from Korean Nuruk during the preparation of rice koji, which is used in brewing the Korean rice wines, Takju and Yakju. Rice koji was made under different culture conditions, and the acidity of each koji was tested. The temperature range suitable for the production of organic acid was $28{\sim}32^{\circ}C$, and 36~48 hours of cultivation at that temperature range seemed to produce the optimum results. The production of organic acid increased in proportion to the increase in water content of steamed rice from 25% to 60%. An increase in koji-thickness induced no adverse effects on the production of organic acid, and agitation-work during cultivation showed very beneficial effects.

• Korean Journal of Food Science and Technology
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• v.6 no.3
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• pp.127-132
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• 1974

This experiment was carried out to investigate the producing conditions of organic acid and saccarifing amylase in Koji culture by Asp. usamii shirousamii $U_2$. The results were as follows. 1. When the strain $U_2$ was incubated at $30^{\circ}C$, for 3 days in wheat flour and wheat bran media, the organic acid production was maximum. In the case of incubation at $35^{\circ}C$, for 3 days in wheat flour medium and at $35^{\circ}C$, for 2 days in wheat bran medium the activity of saccharifing amylase was highest. 2. When water was added 60% to wheat flour and 50% to wheat bran in the case of 3 days incubation, the organic acid production was superior. Both in wheat flour and wheat bran media, the saccharifing amylase production was most highly, when water was added 90-100%. 3. Comparatively speaking, the organic acid production was better in wheat flour medium than wheat bran medium, but the activity of saccharifing amylase was higher in wheat bran medium. 4. When the sweet potato starch waste and the wheat flour were mixed with same amount, the organic acid and saccharifing amylase production were higher than in simple wheat flour medium. 5. In the medium of sweet potato starch waste the organic acid and saccharifing amylase production were low extremely. 6. In the case of incubation at $30^{\circ}C$, 3 days in wheat flour medium admixed with 60% water, the amount of citric acid in the organic acid formed was about 91%.

• Journal of Animal Science and Technology
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• v.49 no.4
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• pp.481-490
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• 2007

An experiment was conducted to investigate the effects of dietary supplementation of MOS, lectin and organic acid mixture(Organic acid F, Organic acid G) on the egg production, egg quality, profile of leukocytes and erythrocytes, small intestinal microflora and immune response in laying hens. A total of 900 Hy-line BrownⓇ laying hens of 48 wks old were assigned to one of the following 6 dietary treatments:control(C), C+AvillamycinⓇ 6ppm, C+MOS 250ppm, C+lectin 12.5ppm, C+Organic acid F(formic acid 35.4%, formate 34.6%, potassium 30.0%) 0.3% and C+0rgarnic acid G(fumaric acid 23%, calcium formate 14%, potassium sorbate 5%, calcium propionate 7%) 0.06%. Each treatment was replicated five times with thirty birds per replicate, housed in 2 bird cages. Feeding trial lasted for 6 wks under 16 hours lighting regimen. All supplemental groups were higher than the control in 6 wks hen-day and hen-housed egg production showing the highest with MOS treatment(P<0.05). Soft & broken egg productions were lower in supplemental groups than in the control except lectin treatment(P<0.05). Eggyolk color of supplemental groups was higher than that of the control except Organic acid G treatment(P<0.05). The values of RBC, HB, MCHC were highest in lectin treatment and lowest in MOS treatment(P<0.05). The numbers of intestinal microflora were not significantly different among the treatments. Serum IgG levels of all supplemental groups were higher than those of the control(P<0.05). In conclusion, for supplementation of antibiotics, immune modulators and organic acid mixture improved production parameters in general. Among the supplements, MOS showed the best performance in egg production and eggyolk color.

• Journal of Dairy Science and Biotechnology
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• v.40 no.1
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• pp.23-34
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• 2022

In this study, to determine the importance of lactic acid bacteria (LAB) in Kombucha fermentation, biological functions, such as organic acid production and anti-inflammatory and antibacterial activities, of Kombucha, with or without LAB inoculation, were evaluated. Lactobacillus paracasei DK215, Saccharomyces cerevisiae C3, and Acetobacter pasteurianus P2 were selected as the inoculants. Organic acids were measured every 3 days from the end of fermentation using HPLC; the organic acid content of LAB-inoculated Kombucha was relatively high. Samples with or without LAB inoculation showed high antibacterial activity against Escherichia coli. The MTT assay results indicated no significant difference in concentration difference and cell death. In the NO production test, compared with the uninoculated Kombucha sample, the LAB-inoculated Kombucha sample exhibited a value similar to that of the group without LPS treatment. The levels of cytokine (IL-1α, IL-6, TNF-α) production were significantly lower than those of the LPS(+) group, indicating the anti-inflammatory activity potential of the Kombucha sample. This improvement in the biological function of the LAB-inoculated Kombucha further verifies the value of LAB in the fermented food and beverage industry.

• Mycobiology
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• v.48 no.2
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• pp.122-132
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• 2020

Citric acid is a commercially valuable organic acid widely used in food, pharmaceutical, and beverage industries. In this study, 260 yeast strains were isolated from soil, bread, juices, and fruits wastes and preliminarily screened using bromocresol green agar plates for their ability to produce organic acids. Overall, 251 yeast isolates showed positive results, with yellow halos surrounding the colonies. Citric acid production by 20 promising isolates was evaluated using both free and immobilized cell techniques. Results showed that citric acid production by immobilized cells (30-40 g/L) was greater than that of freely suspended cells (8-19 g/L). Of the 20 isolates, two (KKU-L42 and KKU-L53) were selected for further analysis based on their citric acid production levels. Immobilized KKU-L42 cells had a higher citric acid production rate (62.5%), while immobilized KKU-L53 cells showed an ~52.2% increase in citric acid production compared with free cells. The two isolates were accurately identified by amplification and sequence analysis of the 26S rRNA gene D1/D2 domain, with GenBank-based sequence comparison confirming that isolates KKU-L42 and KKU-L53 were Candida tropicalis and Pichia kluyveri, respectively. Several factors, including fermentation period, pH, temperature, and carbon and nitrogen source, were optimized for enhanced production of citric acid by both isolates. Maximum production was achieved at fermentation period of 5 days at pH 5.0 with glucose as a carbon source by both isolates. The optimum incubation temperature for citric acid production by C. tropicalis was 32 ℃, with NH₄Cl the best nitrogen source, while maximum citric acid by P. kluyveri was observed at 27 ℃ with (NH₄)₂ SO₄ as the nitrogen source. Citric acid production was maintained for about four repeated batches over a period of 20 days. Our results suggest that apple and banana wastes are potential sources of novel yeast strains; C. tropicalis and P. kluyveri which could be used for commercial citric acid production.