• Korean Journal of Food Science and Technology
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• v.41 no.6
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• pp.681-686
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• 2009

Cronobacter spp. (Enterobacter sakazakii) is known to be highly resistant to dry conditions than any other Enterobacteriaeae. In this study, one hundred and ten Korean Cronobacter isolates were characterized to find out their survival characteristics under conditions of desiccation and humidity. Thirty percentage strains of the isolates showed high resistance to desiccation exposed on the metal surface for eight hours by half survival of the initial number, whileas less than 10% strains showed dry sensitivity by less one log scale survival among seven log scales. Finally, more than 90% of the strains consisted of dry-resistant and dry-intermediate groups. The same tendencies were evident in a 15-day exposure. Dry-resistant and intermediate strain groups showed 3 log scale survival among 5 log initial numbers in the powdered infant formula for 30 days, which were more resistant than on the above metal surface exposed. So, almost the isolate strains showed high resistance to dry condition. Dry-resistant and intermediate groups exposed on the metal surface formed a biofilm at the beginning, and the dry-sensitive group showed biofilm formation mainly only after a 7-day exposure. However, without a time difference in formation of biofilm, the dry-resistant and sensitive isolates seemed to similar biofilm formation activity. Most of the isolates showed very low survival at 75% relative humidity in 48 hours; however, they showed high resistance by 60% survival at 40% relative humidity. The Cronobacter isolates showed high resistance to desiccation on the metal surface and in the powdered infant formula, but low survival at high relative humidity. Therefore, high humidity may be a control method for Cronobacter in food processing environments.

• The Korean Journal of Food And Nutrition
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• v.26 no.4
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• pp.936-944
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• 2013

Cronobacter muytjensii is an important foodborne pathogen as a potential risk in infant formula powder (IFP). To develop a new and sensitive method for the detection of Cronobacter spp. in IFP, an immunoglobulin G (IgG) specific for C. muytjensii (formerly known as Enterobacter sakazakii ATCC 51329) was developed. Further, an indirect noncompetitive enzyme-linked immunosorbent assay (INC-ELISA) was developed by using the anti-C. muytjensii IgG. As a result, this newly developed INC-ELISA method was found very sensitive for C. muytjensii with detection limit of $6.5{\times}10^3CFU/ml$ in pure culture and 1 cell/25 g of IFP. This INC-ELISA method also displayed excellent specificity for C. muytjensii showing no cross-reactivity with other strains of Cronobacter genus and 11 other foodborne pathogenic strains. These results show that the developed INC-ELISA method was very sensitive, efficient, and rapid for the detection of C. muytjensii. Hence, this method could be applied to the development of diagnostic kits for the rapid and easy detection of C. muytjensii.

• Journal of Food Hygiene and Safety
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• v.25 no.4
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• pp.341-345
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• 2010

Three-hundred samples of powdered infant formula milk and related products from four different manufacturers in 2010 were collected and surveyed their contaminations for aerobic bacteria, coliform, Enterobacter(Cronobacter) sakazakii, and food-borne pathogens. Fifteen samples of sterilized infant formula milk were all negative on these microorganisms. In all collected products of un sterilized infant formulas and follow-on infant formulas, aerobic bacteria were detected at 239 (83.9%) among 285 samples, and they all were found below $10^3$ cfu/g. Coliform bacteria were also detected at four among 285 samples. Salmonella spp. and Ent. sakazakii, weren't detected at the all samples. Bacillus cereus was detected at 24 (8.4%) among 285 samples. The level of B. cereus was below 100 cfu/g but it was suitable for the range of specification of B. cereus in infant formulas. Clostridium perjringens, Escherichia coli O157:H7, Staphylococcus aureus and Listeria monocytogenes weren't also detected. In consequence, it was suitable for total viable count, coliform and potential pathogen to the specification of infant formulas and related products.