Analysis of the Relationship of Microbial Contamination with Temperature and Cleaning Frequency and Method of Domestic Refrigerators in Japan

摘要

Hygiene management of domestic refrigerators is an important aspect of food poisoning prevention. The aim of the present study was to confirm the relationship between microbial contamination and hygiene management by measuring microbial levels and investigating temperature and cleaning frequency and method of domestic refrigerators in Japan. We analyzed three internal sections (the egg compartment, bottom shelf, and vegetable drawer) of 100 domestic refrigerators in Japan. Salmonella, Listeria monocytogenes, and Yersinia enterocolitica were not found in any of the refrigerators, but coliforms and Escherichia coli were detected in more than one household, and Staphylococcus aureus was the most frequently isolated pathogen. The prevalences of these microorganisms had similar tendencies in all three sections sampled and were highest in the vegetable drawer. The temperature distribution in the refrigerators was also investigated, and a temperature ＞6.1°C (improper temperature) was found in 46.2% of the areas surveyed. Only 17% of the respondents cleaned their refrigerators monthly or more often, and this frequency was lower than that reported in other countries. Fifty percent of the respondents used only water to clean the refrigerator, 10% used only an alcohol or disinfecting wipe, and 8% used only a dry cloth. Although no significant correlations were found between microbial contamination and temperatures in refrigerators, correlations were found between microbial contamination and refrigerator cleaning frequency and/or method. To our knowledge, this is the first detailed survey concerning relationships between microbial contamination and hygiene management in domestic refrigerators in Japan. The data obtained can be used to promote food poisoning management in Japanese households.