• Korean Journal of Food Science and Technology
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• v.29 no.5
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• pp.919-924
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• 1997

The changes in physicochemical properties of cooked rice stored in an electric rice cooker at different temperature (63, 66, 69 and $72^{\circ}C$) were investigated. The growth of thermophilic bacteria was gradually increased in all samples with storage time up to 6 hours and increased rapidly afterward. The bacterial growth rate was higher during storage at low temperature than at high temperature, and the bacterial number generally reached the maximum at 18 hours of the storage. The number of bacteria in sample stored at $63^{\circ}C$ was increased to $10^6$ CFU/g after storage for 6 hours. The heat treatment at 6 hours of storage decreased the bacterial number to $10^5 $ CFU/g at 8 hours of storage. Bacterial number was gradually increased with storage time after the first heat treatment. When the sample was reheated after 8 hours of storage, the bacterial number was reduced to the level at which off-odor was not detected after storage for 24 hours. During the storage, moisture content of heat-treated sample was lower than that of sample stored at $63^{\circ}C$ but higher than that of sample stored at $72^{\circ}C$. The L value of heat-treated sample was higher than that of the sample stored at $72^{\circ}C$, but lower than that of the sample stored at $63^{\circ}C$. The b value showed an opposite trend to the L value with regard to the storage temperature. Changes in texture were not remarkable during the storage for the sample heat-treated and stored at low temperature. The occurrence of off-odor and browning was depressed in the heat-treated sample, and the texture and overall eating quality were more acceptable than the samples stored at low temperature.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.1
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• pp.28-35
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• 1999

The effects of addition of celulases (A cremonium cellulolyticus and Trichoderma viride, CE), a commercial inoculum containing lactic acid bacteria (Lactobacillus casei, LAB), fermented green juice (macerated napier grass with water was incubated anaerobically with 2% glucose for 1 day, FGJ) and glucose (G), and regional difference of ensiling on napier grass (Pennisetum purpureum Schum.) silage were studied by using 900 ml laboratory glass bottle silos under 30 and $40^{\circ}C$ storage conditions in 1995 and 1996. Experiment 1 was carried out to compare the addition of CE, LAB, FGJ and the combinations. Silages were stored for 45 days after ensiling. Experiment 2 studied the effects of applications of CE, LAB, FGJ and G. Experiment 3 was carried out using the similar additives as experiment 2 except for LAB. Silages were stored for 60 days in the experiments 2 and 3. Experiments 1 and 2 were done in Nagoya, and experiment 3 in Okinawa. Sugar addition through CE or G improved the fermentation quality in all the experiments, which resulted in a greater decrease in the pH value and an increased level of lactic acid, while butyric acid contents increased under $30^{\circ}C$ storage condition in CE addition. LAB and FGJ additions hardly affected the silage fermentation quality without additional fermentable carbohydrate. But the combination of LAB, FGJ and glucidic addition (CE and G) improved the fermentation quality. The effect of the regional difference of ensiling between temperate (Nagoya; $35^{\circ}$ N) and subtropical (Okinawa; $26.5^{\circ}$ N) zones on silage fermentation quality was not shown in the present study.

• Journal of Microbiology and Biotechnology
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• v.26 no.4
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• pp.648-658
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• 2016

Preservation of fresh algae plays an important role in algae seed subculture and aquaculture. The determination and examination of the changes of cell viability, composition, and bacterial species during storage would help to take suitable preservation methods to prolong the preservation time of fresh algae. Nostoc flagelliforme is a kind of edible cyanobacterium with important herbal and dietary values. This article investigated the changes of bacterial species and biochemical characteristics of fresh N. flagelliforme concentrate during natural storage. It was found that the viability of cells decreased along with the storage time. Fourteen bacteria strains in the algae concentrate were identified by PCR-DGGE and were grouped into four phyla, including Cyanobacteria, Firmicutes, Proteobacteria, and Bacteroidetes. Among them, Enterococcus viikkiensis may be a concern in the preservation. Eleven volatile organic compounds were identified from N. flagelliforme cells, in which geosmin could be treated as an indicator of the freshness of N. flagelliforme. The occurrence of indole compound may be an indicator of the degradation of cells.

• Korean journal of food and cookery science
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• v.6 no.2
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• pp.51-58
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• 1990

Quality deterioration of barley drink during storage was examined by measuring viable count, titratable acidity (TA), turbidity and pH of barley drinks with or without barley particles stored at temperatures of 20, 25, 30, and 35$^{\circ}C$. Qualitative analysis of organic acids in spoiled barley drink was also performed. TA of barley drink during storage increased to 0.009, 0.0095, 0.0097 and 0.020% at 20, 25, 30 and 35$^{\circ}C$, respectively. TA reached the mixima between 7 and 10 days of storage and reduced from then on. pH values followed the exactly reverse trend of TA. The rate of bacterial spoilage of barley drinks was faster when it was stored at higher temperatures. The numbers of bacteria were in the range between 9.0${\times}10^6-8.0{\times}10^8$ cells/ml depending on the storage temperatures and the different brands. Those samples with higher bacterial growths showed higher optical densities. Volatile organic acids such as acetic, formic, propionic, isobutyric, isovaleric acids were detected in addition to ethyl alcohol. Non-volatile organic acids such as pyruvic, lactic, oxalacetic, succinic, fumaric acids were detected. Among them, acetic acids were most important in their quantities. Five different kinds of spoilage bacteria were isolated and identified as Bacillus Licheniformis, Bacillus coagulans, Badillus cirulans, Bacillus stearothermophilus and Bacillus brevis, all of which were found to form endospores.

• Korean Journal of Food Science and Technology
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• v.25 no.4
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• pp.340-344
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• 1993

Gel type yoghurts from 5 representative manufacturers were collected at market and evaluated their physico-chemical properties during storage at $5^{\circ}C$. The range of pH, acidity, Brix and viscosity of each product were $3.87{\sim}4.19,\;0.97{\sim}1.42%,\;16.2{\sim}22.2\;and\;7,850{\sim}21,000 cp$ respectively. The pH of each product decreased gradually during storage time and reached around pH 4.1 after 16 days with proportional acidity increasing. The viscosity of all test products showed increasing trend by lactic acid bacterial action. Total lactic acid bacteria were $10^8{\sim}10^9\;CFU/ml$ at the beginning storage and increased or decreased depending upon each product. But all product maintained over than $10^8 CFU/ml$ which meets regulatory level after 16 days storage.

• Korean Journal of Food Science and Technology
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• v.16 no.1
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• pp.47-50
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• 1984

Effects of irradiation on microbiological, physicochemical aspects and quality of onion powder were investigated during three months storage. Total bacteria and coliform were sterilized by irradiation of 7 and 5 kGy, respectively and no microorganisms were grown after three months storage at $30{\pm}1^{\circ}C$. $D_{10}$ value of total bacteria was 1.64 kGy. Proximate composition of onion powder was not remarkably changed during storage except the slight decrease of pyruvic acid content. Color difference could not be distinguished by naked eye but was slightly changed by the mechanical measurement.

• Food Science and Preservation
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• v.10 no.2
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• pp.136-141
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• 2003

This they was conducted to investigate the surface treated effect of Packaged kimchi on the PH, acidity, total microbe, number of lactic acid bacteria, browning and formation of off-flavor during storage at 10$^{\circ}C$. Kimchi was treated with 70% ethanol(1 time spraying) and attachment of polyethylene film(PE) on the surface of packaged kimchi and stored at 10$^{\circ}C$. pH of the control and ethanol treated kimchi stored for 15 days was decreased to 4.0 level but, the pH of PE-treated kimchi maintained over pH 4.0 until 21 days of storage. The aridity was the same tendency as the pH, which showed delaying of fermentation by PE treatment. Total microbe of PE treated kimchi was lower and number of lactic acid bacteria was higher than those of control and ethanol treated products, respectively. Degree of browning and off-flavor of control and ethanol treated kimchi increased from 13 days of storage, but the degrees of the PE-treated kimchi was lower during all storage periods.

• Food Science and Preservation
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• v.6 no.4
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• pp.456-462
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• 1999

The radish juice inoculated with mixed culture of Leuconostoc mesenteroides and Lactobacillus brevis was fermented and stored. Radish juice was heat-treated for 30 min at 65$^{\circ}C$ and 15 min at 80$^{\circ}C$, and stored for 8 weeks at 25$^{\circ}C$, 15$^{\circ}C$, and 5$^{\circ}C$, respectively. When the radish juice was heat-treated, any bacteria were not detected and any quality changes were not occured. On the other hand non-heated radish Juice, pH was decreased and acidity was increased during storage. The turbidity of the heat-treated radish juice was higher than that of the non-heated juice when it stored at 5'E. From the sensory evaluation, the pasteurization condition of 15 min at 80$^{\circ}C$ was not appropriate because the fresh smell of Dongchimi was decreased and the cooked smell was increased. The radish juice stored at 5$^{\circ}C$ without heat-treatment was evaluated to have the best quality. The storage period of the non-heated radish juice was shown to be extended over 8 weeks at 5$^{\circ}C$.

• Animal Bioscience
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• v.37 no.1
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• pp.123-130
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• 2024

Objective: Beef of Jeju black cattle (JBC) is considered as a healthy meat type due to its significantly higher unsaturated fatty acids (UFA). Lipid (e.g., UFA) is highly susceptible to oxidizing agents, which results in the quality deterioration and economic value loss of meat products. Therefore, development and application of novel preservative techniques is necessary to improve the shelf-life stability of high-UFA beef. The objective of this study was to assess the applicability of chitosan-based coatings in preservation of JBC beef. Methods: Different coating solutions: 2% chitosan alone, and 2% chitosan containing 0.1% or 0.3% gallic acid were prepared to investigate their applicability in preservation of fresh beef during storage. Jeju black cattle beef (2-cm thick steaks) were non-coated (control) or coated with the above coating solutions, placed on trays, over-wrapped with plastic film and stored at 4℃. The microbiological indices, color, total volatile basic nitrogen (TVBN) and lipid oxidation of the beef were investigated after 1, 10, and 21 days of storage. Results: Coating with 2% chitosan alone reduced the spoilage bacteria count, TVBN and thiobarbituric acid reactive substances levels in the beef compared with control during storage (p<0.05). Noticeably, coating with 2% chitosan containing 0.1% or 0.3% gallic acid was more effective on retardation of spoilage bacteria growth, lipid oxidation and discoloration in the beef compared to the chitosan coating alone over the storage period (21 days) (p<0.05). Conclusion: Taken together, the combined chitosan and gallic acid coating could be used as a bio-preservative technique in the meat industry.

• Journal of Food Hygiene and Safety
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• v.35 no.2
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• pp.170-176
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• 2020

We investigated the pH, volatile basic nitrogen (VBN), microbial changes and dominant microbes in raw beef, wet-aging beef, and dry-aging beef after the meat had been stored in a refrigerator. The count of mesophilic bacteria was 3.3-3.9 log CFU/g in raw beef and dry-aging beef, and 5.4 log CFU/g in wet-aging meat. After 18 days of refrigeration, the mesophilic bacterial count in raw and aging beef increased to 6.1-6.4 log CFU/g. In wet-aging beef, the number of lactic acid bacteria increased from 4.5 log CFU/g to 6.0 log CFU/g at refrigeration temperature. However, lactic acid bacteria were not detected in dry aging beef. Major foodborne pathogens such as Salmonella spp, Listeria monocytogenes, and Escherichia coli (EHEC) were not detected. Based on the legal standard for mesophilic bacteria count, the estimated shelf-life of aged beef was less than 12 days and the average VBN was 15 mg%. The dominant microorganisms varied between the different types of meat. In raw meat, Staphylococcus saprophyticus was the dominant microorganism, and as the VBN increased, Carnobacterium divergens dominated. In wet-aging beef, Carnobacterium divergens dominated during the initial days of refrigeration after which the number of Lactobacillus sakei increased. Dermacoccus nishinomiyaensis was initially the dominant microbe in dry-aging beef, after which Pseudomonas fragi dominated. In addition to the role of specific bacteria in the early stage of decay, it is thought that microorganisms can be utilized for safe distribution and storage of matured meats by conducting research on changes in rot, fragrance analysis, and changes of ingredients in matured meats.