Temperature distribution and hygienic status of domestic refrigerators in Lemnos island, Greece

Chilling is a common food preservation practice applied overwhelmingly in the domestic environment through refrigerator use. Nevertheless, the hygiene conditions and temperatures prevailing in household refrigerators are often inappropriate. Moreover, the way of life in non- or semi-urban settings (e.g., less stress intensive life), such as those encountered in most Greek islands, imposes changes in consumer behavior which are probably being reflected in the domestic hygiene. The purpose of this research was to investigate the hygienic status and temperature distribution of the domestic refrigerators in Lemnos island, Greece. Seventy refrigerators (n = 70) were surveyed by placing temperature data loggers in three different storage areas of each refrigerator (upper shelf, lower shelf, door) and temperature was recorded every 15 min for 24 h. Placement of food in the refrigerators was also monitored and assessed using a predetermined questionnaire. Two food-contact surface samples from each storage area of the refrigerator were collected by swabs (n = 6) for microbiological analyses (total viable count; TVC, total coliforms, Escherichia coli, Staphylococcus spp., Salmonella spp., and Listeria spp.). The results demonstrated that only 11.4% of the refrigerators were operating below or equal to 5 °C, whereas most refrigerators (68.6%) were found to operate at temperatures over 7 °C. The majority (77.1%) of survey participants did not correctly place their food commodities in the fridge, according to standard good hygiene practices (GHPs). Salmonella and Listeria were not detected in the refrigerators (i.e., absence in 100 cm²), while E. coli was not recovered (i.e., <1 CFU/cm²) from any of the refrigerator's storage areas. TVCs and total coliforms ranged above the adopted reference values of 1.3 and 1.0 log CFU/cm² in 41.4 and 2.9% of the refrigerators, respectively. Staphylococci were above the settled limit of 1.0 log CFU/cm² in 8.6% of the refrigerators, but S. aureus counts were always below this limit (i.e., <1.0 log CFU/cm²). Overall, although the monitored microbiological safety of the sampled domestic refrigerators was satisfactory, the percentage of refrigerators exceeding the acceptable limit in TVC indicates poor cleanliness of home fridges. In addition, both the operating temperatures and placement of food in the refrigerators in many cases did not comply with the recommended GHPs, suggesting a potential risk for the microbiological safety and expected shelf-life of refrigerated food in the kitchen environment. To sum, the present study highlights the necessity of increased consumer awareness and emphasizes the need for further education of the household consumer in proper GHP implementation in their fridges.