• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.3
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• pp.193-197
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• 2003

Psychrotrophic characteristics of Listeria monocytogenes YM-7 showed similar growth at $8^{\circ}C$ as L. monocytogenes ATCC 15313. But it showed different growth pattern at $4^{\circ}C.$ Thus the isolated strain from the Patient can not grow at $4^{\circ}C,$ while L. monocytogenes ATCC 15313 grow slowly. Number of the injured cells of L. monocytogenes YM-7 was higher at $-3^{\circ}C$ than at $-18^{\circ}C$ in phosphate buffer solution. The rate of the injured cell was higher in the TSB (tryptic soy broth) medium than in phosphate buffer solution at $-3^{\circ}C$ and $-18^{\circ}C.$ When L. monocytogenes YM-7 stored at $-18^{\circ}C$ in homogenized fish muscle, the cell numbers decreased by 2-3 log cycles in 12 weeks.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.4
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• pp.443-450
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• 1995

Listeria monocrogenes has been increasingly recognized as an important food poisoning and pathogenic bacterium which is Gram positive, non spore forming and facultative anaerobic rod shape. Bacteriological and physiological characterization of L. monocytogenes YM-7 isolated from a patient was performed. Optimum growth condition of 1. monocytogenes YM-7 was at $37^{\circ}$, pH 8.0 and $0\%$ sodium chloride in tryptic soy broth, and then it grew pretty well in the range of $8-40^{\circ}C,\;pH 5.0-10.0\;and\;up\;to\;7\%$ of sodium chloride in the medium. The highest hemolysin activity of hemolysin produced by L. monocytogenes YM-7 was shown in the stationary phase of its growth. Hemolysin produced by the isolated strain was stable at $4^{\circ}C\;and\;pH\;6.0-8.0, while it was gradually unstable by increasing the storage temperature.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 1995.06a
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• pp.282-284
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• 1995

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 1995.06a
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• pp.285-287
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• 1995

• Journal of Food Hygiene and Safety
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• v.37 no.2
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• pp.87-96
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• 2022

Recently, the purchase of fresh-cut produce and meal kits has increased. Ready-to-eat (RTE) fresh-cut products have potentially hazard of cross-contamination of various microorganisms in the processes of peeling, slicing, dicing, and shredding. There are frequent cases of protozoa food poisoning, such as Cyclospora and Cryptosporidium, caused by fresh-cut products. The objective of the study is to investigate the microbiological qualities of various types of RTE fresh-cut products in the domestic on/offline markets. RTE fresh-cut fruits cup (n=100), fresh-cut vegetables (n=50), and vegetables in meal kits (Vietnamese spring rolls and white radish rolls kits, n=50) were seasonally analyzed. The contamination levels of hygienic indicator organisms, yeast and mold (YM), and foodborne pathogens (Bacillus cereus, Staphylococcus aureus, Listeria monocytogenes, Salmonella spp., and Escherichia coli O157:H7) were monitored. Overall, the lowest microbiological qualities of meal kits vegetables were observed, followed by RTE fresh-cut fruits cup and fresh-cut vegetables. Contamination levels of total aerobic bacteria, coliforms, and YM in meal kits vegetables were 5.91, 3.90, and 4.71 logs CFU/g, respectively. From the qualitative analysis, 6 out of 200 RTE fresh-cut products (3%) returned positive result for S. aureus. From the quantitative analysis, the contamination levels of S. aureus in purple cabbage from a meal-kit and fresh-cut pineapple were below the acceptable limit (100 CFU/g). Staphylococcus enterotoxin seg and sei genes were detected in RTE fresh-cut celery and red cabbage from meal-kits, respectively. S. aureus contamination must be carefully controlled during the manufacturing processes of RTE fresh-cut products. Neither Cyclospora cayetanensis nor Cryptosporidium parvum was detected in the samples of RTE fresh-cut products and vegetables from meal-kits from the Korean retail markets.