• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.439-439
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• 2003

• Food Science and Biotechnology
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• v.14 no.6
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• pp.803-807
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• 2005

This study examined the effects of ozone exposure alone (1, 3, and 5 ppm) as well as in combination with 1% acetic acid, citric acid, or lactic acid on the growth of indigenous microorganisms in enoki mushrooms. Populations of mesophilic bacteria, yeasts and molds in enoki mushrooms appeared to be decreased by stepwise increases in concentration (1 to 5 ppm) or exposure time (0.5 to 5 min) to ozone. Compared to untreated (control) enoki mushrooms, there were reductions of 1.03 to $2.61\;\log_{10}\;CFU/g$ in mesophilic bacteria and of 1.21 to $2.7\;\log_{10}\;CFU/g$ in yeasts and molds in all ozone- treated enoki mushrooms. Combination of 3 ppm ozone and 1% citric acid (p<0.05) synergistically brought about significant reductions in both mesophilic bacteria ($3.52\;\log_{10}\;CFU/g$) and fungi (yeasts and molds) ($2.77\;\log_{10}\;CFU/g$) from enoki mushrooms. The results of this study show that low concentrations of ozone inhibit indigenous microflora populations in enoki mushrooms. Combination treatments of 3 ppm ozone with 1% citric acid showed greater antimicrobial effectiveness than either 3 ppm ozone or 1% citric acid alone.

• Asian-Australasian Journal of Animal Sciences
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• v.29 no.7
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• pp.965-970
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• 2016

This study was conducted to determine the effects of freezing and supplementation of molasses (M), lactic acid bacteria (LAB) and LAB+enzyme mixture on chemical and nutritional composition of sunflower silage (SF). Sunflower crops were harvested (at about $29.2%{\pm}1.2%$ dry matter) and half of fresh sunflower was ensiled alone and half was frozen (F) at $-20^{\circ}C$ for 7 days. Silage additives were admixed into frozen SF material. All samples were ensiled in glass jars with six replicates for 90 days. The treatments were as follows: i) positive control (non-frozen and no additives, NF), ii) negative control (frozen, no additives, F), iii) F+5% molasses (FM), iv) F+LAB (1.5 g/tons, Lactobacillus plantarum and Enterococcus faecium, FLAB); v) F+LAB+enzyme (2 g/tons Lactobacillus plantarum and Enterococcus faecium and cellulase and amylase enzymes, FLEN). Freezing silage increased dry matter, crude ash, neutral detergent fiber, and acid detergent lignin. The organic matter, total digestible nutrient, non-fiber carbohydrate, metabolizable energy and in vitro dry matter digestibility were negatively influenced by freezing treatments (p<0.05). In conclusion, freezing sunflower plants prior to ensiling may negatively affect silage quality, while molasses supplementation improved some quality traits of frozen silage. Lactic acid bacteria and LAB+enzyme inoculations did not effectively compensate the negative impacts of freezing on sunflower silage.

• Journal of Dairy Science and Biotechnology
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• v.37 no.2
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• pp.83-93
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• 2019

Food spoilage by fungi is responsible for considerable food waste and economical losses. Among the food products, fermented dairy products are susceptible to deterioration due to the growth of fungi, which are resistant to low pH and can proliferate at low storage temperatures. For controlling fungal growth in dairy products, potassium sorbate and natamycin are the main preservatives used, and natamycin is approved by most countries for use in cheese surface treatment. However, a strong societal demand for less processed and preservative-free food has emerged. In the dairy products, lactic acid bacteria (LAB) are naturally present or used as cultures and play a key role in the fermentation process. Fermentation is a natural preservation technique that improves food safety, nutritional value, and specific organoleptic features. Production of organic acids is one of the main features of the LAB used for outcompeting organisms that cause spoilage, although other mechanisms such as antifungal peptides obtained from the cleavage of food proteins and competition for nutrients also play a role. More studies for better understanding these mechanisms are required to increase antifungal LAB available in the market.

• KSBB Journal
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• v.30 no.1
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• pp.33-37
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• 2015

Recently, several health benefits of rice wine, makgeolli, were known due to the interest on the traditional Korean liquor and the researches on the rice wine are increasing. Organic acids produced during the process of rice wine fermentation play important roles in the taste and flavor. In this study, we have examined the optimal conditions for lactic acid production in rice koji as a carbon source. Skim milk was also used as a supplementary ingredient for the optimization of lactic acid fermentation. Bacterial growth of Lactobacillus sakei was monitored under this condition. The pH, acidity of the culture and the ethanol tolerance of this bacterium were also tested. Through these experiments, we were able to optimize the growth condition of lactic acid bacteria by the addition of skim milk. This was also able to affect the change of pH, acidity, sugar concentration and alcohol tolerance, which might contribute to the improvement of the quality of rice wine. The optimal condition for the growth was 2 days with 10% (w/v) of skim milk concentration. With these results, it was confirmed that rice koji was an effective carbon source for the growth of lactic acid bacteria.

• Preventive Nutrition and Food Science
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• v.1 no.1
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• pp.37-40
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• 1996

Kinchi is and important source of various vitamins, minerals, dietary fiber, organic acids and other nutrients. In order to get a basic information for developing vitamins-rich funtional kimchi, we investigated microorganisms which are capable of synthesis of vitamin C in Kimchi system. Microorganisms isolated from aliquots of kimchi were screened and cultured by using MRS or nutrient agar medium. L-Ascorbic acid produced by microorganism in medium was measured with high performance liquid chromatography. As the result, we isolated two bacteria strins N7 and N5202 preducing L-ascorbic acid from the kimchi system. Morphological and Gram staining experiment showed that N7 was Gram positive bacilli, while N5202 was Gram negative. There were also several bacteria that were considered to synthesizs erythorbic acid which is an analog of ascorbic acid. These results suggested that vitamin C-rich functional food could be developed by using the kimchi microorganisms.

• Journal of Environmental Science International
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• v.30 no.12
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• pp.1093-1100
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• 2021

The present study investigated the effect of ammonia load on microbial communities in mesophilic anaerobic digestion of propionic acid. A laboratory-scale continuous anaerobic digester treating propionic acid as a sole organic substrate was operated under non-inhibitory condition and inhibitory conditions with ammonia (1.5 g and 3.5 g ammonia-N/L, respectively), and bacterial and archaeal communities in the steady states of each ammonia condition were analyzed using high-throughput sequencing. Thirteen bacterial families were detected as abundant bacterial groups in mesophilic anaerobic digestion of propionic acid. Increase in ammonia concentration resulted in significant shifts in microbial community structures. Syntorophobacter, Pelotomaculum, and Thermovigra were determined as the dominant groups of (potential) propionate oxidizing bacteria in the non-inhibitory condition, whereas Cryptanaerobacter and Aminobacterium were the dominant groups of (potential) propionate oxidizing bacteria in the ammonia-inhibitory condition. Methanoculleus and Methanosaeta were the dominant methanogens. Acetate-oxidation coupled with hydrogenotrophic methanogenesis might be enhanced with increases in the relative abundances of Methanoculleus and Tepidanaerobacter acetatoxydans under the ammonia-inhibitory condition. The results of the present study could be a valuable reference for microbial management of anaerobic digestion systems that are exposed to ammonia inhibition and propionic acid accumulation.

• Journal of the Korea Organic Resources Recycling Association
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• v.4 no.2
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• pp.11-17
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• 1996

Photosynthetic bacteria, strains KN 1-1, KN 2-1 and KN 2-3 were isolated from nature, and were studied for swine wastewater treatment. Growth of those photosynthetic bacteria were increased to 2~3 fold in organic-acid added medium(sodium acetate 1g, sodium propionate 1g and sodium butyrate 1g in Lascelles basal medium $1{\ell}$) than cultivation in Lascelles basal medium, and amount of bacteriochlorophyll a were increased to 1.5~2 fold. Chemical Oxygen Demand(COD) in swine wastewater using photosynthetic bacteria, strains KN 1-1, KN 2-1 and KN 2-3 were reduced 80%, 89% and 75%, respectively.

• Journal of the East Asian Society of Dietary Life
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• v.13 no.4
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• pp.305-312
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• 2003

The effect of addition of ethanol and/or organic acid on slowing down the fermentation of Mul-kimchi was tested by measuring the changes in pH, acidity and counting the number of microorganisms in kimchi fermentation, and sensory evaluation were carried out. The addition of 0~5％ ethanol to kimchi delayed the decrease of pH and the delaying effect during kimchi fermentation was dependent on the ethanol concentration used. The pH of kimchi without ethanol decreased from 5.7 to 4.13, however, the pH of the kimchi added with 5％ ethanol only from 5.8 to 5.14. The increase of acidity in kimchi with 5％ ethanol was only 0.5~0.6％, while that without ethanol was 0.7~0.8％. Among the organic acids tested, adipic acid was found to be most effective on the prevention of kimchi souring. The Mul-kimchi added 2％ ethanol together with 0.1％ organic acid showed similar effect to that of organic acid alone in the change of pH and acidity. By the sensory evaluation, Mul-kimchi with 0.1％ adipic acid and 2％ ethanol was selected the most desirable one except control without any addition. And the numbers of total microbes, lactic bacteria and yeast count, showed the most effective inhibition in Mul-kimchi with 0.1％ adipic acid and 2％ ethanol.

• Journal of Food Hygiene and Safety
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• v.34 no.6
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• pp.591-594
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• 2019

Some strains of Escherichia coli are categorized as pathogenic bacteria and alternative antimicrobials including bacteriophages for controlling these bacteria have been studied. In this study we screened antimicrobial candidates that present synergistic inhibition of the growth of E. coli DH5α as a model when co-treated with the bacteriophage ECP27 to target the bacteria. As candidates, CaCl₂, lactic acid, and citric acid were tested. CaCl₂ showed a synergistic inhibition against the strain by dose-dependent manner at 6 h of incubation but the viable cell count was recovered at 12 h. However, lactic acid and citric acid at 30 mM concentration showed synergistic inhibitions at 6 h of incubation and cleared the viable cells of E. coli DH5α at 12 h when co-treated with the bacteriophage even though lactic acid or citric acid alone was effective. Therefore, co-treatment using the bacteriophage and organic acids such as lactic acid and citric acid can be a solution for synergistic inhibition of the growth of E. coli.