The microbiological quality of washing-up water and the environment in domestic and commercial kitchens

Abstract

Aims: To determine the microbiological quality of washing-up water and the environment in domestic and commercial kitchens. Methods and Results: Chicken meals were prepared by people without food safety training in their own kitchen (n = 52) or by trained staff in a commercial kitchen (n = 10). Study participants then washed-up, cleaned the kitchen and completed a food hygiene questionnaire. The temperature and microbiological quality of the washing-up water, and the presence of pathogens in dishcloths, tea towels and other kitchen samples was determined. Of the raw chickens used in meal preparation, 96 and 13% were naturally contaminated with Campylobacter or Salmonella spp., respectively. In domestic kitchens, two of 45 sponges, dishcloths or scourers and one of 32 hand- or tea towels were contaminated with Campylobacter after washing-up and cleaning but none of the tap or sink swabs yielded pathogens. The mean washing-up water temperature in the domestic kitchens was 40.7°C, whereas in the commercial kitchen it was 44.7°C (P = 0.04). Study participants who used hotter water (≥40°C) had lower levels of bacteria in their washing-up water. The aerobic plate counts of the washing-up water samples in domestic homes were usually between 105 and 106 CFU ml-1 but those associated with the commercial kitchen were consistently lower (P = 0.01). Despite this, Campylobacter was detected in one of 10 washing-up water samples from the commercial kitchen but in none of the samples from domestic kitchens. Conclusions: Pathogenic microorganisms can be recovered relatively frequently from the kitchen environment. Significance and Impact of Study: By identifying factors that affect the number of microorganisms in washing-up water and the kitchen environment, evidence-based recommendations on implementing domestic food hygiene can be made.