PurposeMany cases of food poisoning originate in the domestic environment and can be associated with improper food handling and ineffective cleaning by consumers. These practices could lead to the introduction and spread of bacterial contamination in the kitchen and if not subsequently removed could present an infection risk. This study proposes investigating changes in levels of bacterial contamination at five key sites in ten domestic kitchens during a period of 24 hours.Design/methodology/approachMicrobiological swabs were used to provide an aerobic colony count and an Enterobacteriacea count. A record was kept of cooking, cleaning and other activities within the kitchen.FindingsResults showed that contamination levels varied during the day, peaking after meal preparation and generally falling overnight. There was also indirect evidence of cross contamination, particularly from hands to other surfaces. Sites such as the refrigerator handle, kettle handle and taps, which generally only come into contact with hands, show increases in the levels of contamination recorded. Levels of microbiological contamination were lower in vegetarian than non‐vegetarian households. A variety of data showed that non‐food preparation activities also take place in the kitchen. These could also introduce bacterial contamination into the kitchen and facilitate their spread.Originality/valueThe implications of these results are that the most important time for cleaning in the kitchen is immediately after food has been prepared, with attention focussing on high risk areas such as the work surface, chopping board, taps and other hand contact surfaces.
The possibility exists that environmental dust could be a source of gastro-intestinal infection in the domestic environment and that the causative microbes are collected during vacuum cleaning. This study examines the survival of total bacterial populations, Enterobacteriaceae and salmonella species in vacuum cleaner dust in vitro and in use. Total counts remain constant at around 10(6)-10(8) colony forming units (cfu) g-1 for at least 60 days. Enterobacteriaceae showed only a slight decline over the same period. Recovery of salmonellae artificially inoculated into vacuum dust was dose and time dependent: even relatively small inocula (< 100 cfu g-1) were recoverable more than one month after inoculation. Questionnaires and vacuum cleaner dust samples were received from 76 households. A significant association was found between total bacterial counts and whether the household was in a rural or urban situation and the number of people in the household. No association was found between total bacterial counts and the number of children in the household, the presence of pets, wearing shoes indoors, the makes, model and age of the vacuum cleaner, the type of dust collector or dust bag, how often the vacuum cleaner was used and the length of time between sample collection and microbiological testing. Salmonella species were isolated from vacuum cleaner dust from three of the 76 households although no factors could be identified linking the homes. This study shows that vacuum cleaners are effective collectors and reservoirs of microbial contamination and that these contaminants are able to survive for up to two months. Vacuum cleaner dust could thus be a useful indicator of environmental contamination in the home.
In this study a simple meal was prepared from raw chicken and lettuce in a manner which incorporated examples of common food hygiene malpractice. Prior to meal preparation, the chicken was inoculated with varying levels of Salmonella Typhimurium. The spread of microbial contamination (total viable counts, Enterobacteraceae counts and the presence of Salmonella species) from the chicken to sites in the kitchen was traced. Results indicate how easily bacterial contaminants from food may be spread around a kitchen. Levels of contamination on foods ready for consumption and in areas considered clean after washing up and wiping surfaces are established. These indicate that contaminants are unlikely to be removed from some sites unless cleaning procedures are rigorous.
Purpose -This paper is aimed at food science or biology students planning a practical independent study into the antimicrobial properties of spices and academic staff wishing to develop a straightforward and reproducible practical activity. Design/methodology/approach -Disc-diffusion assays are used to investigate the antimicrobial activity of cinnamon and cloves against two bacteria Escherichia coli B and staphylococcus albus and a yeast Saccharomyces cerevisiae. Aqueous and alcoholic extracts of the spices and alcoholic extracts of their essential oils are examined. Minimum inhibitory concentrations of alcoholic extracts of both spices and oils are also determined. Findings -Both spices demonstrated microbial inhibitory effects; alcoholic extracts had greater activity than aqueous extracts. Additionally, essential oils had greater activity than the spices. Minimum inhibitory concentrations were smaller with the oils than with the spices. Research limitations/implications -Although the research for this paper involved just two spices, such is the size of the plant kingdom that there are wide opportunities for further investigations using this procedure. Practical implications -Disc-assays were found to be a simple, cheap and reproducible practical method. For this paper, micro-organisms available for educational purposes were used; however, other organisms could be investigated depending upon available microbiological expertise and facilities. Originality/value -The results demonstrate that the antimicrobial effects of spices and particularly their essential oils can be examined using disc-diffusion assay. The method provides many opportunities for student investigation.
The killing or removal of microbes from the hands is a critical factor in food safety as many studies have shown the hands to be both an important source of microbes and powerful agents of cross‐contamination in hospital and domestic situations. In response to this concern, a number of novel hand‐washing products have appeared on the market. These products contain anti‐microbial agents and claim to be more effective at removing bacteria than soap bars and conventional liquid soaps. This study attempts to test these claims by comparing the effectiveness of a conventional soap bar, a conventional liquid soap and an anti‐microbial liquid soap containing triclosan. In vitro tests demonstrate that the anti‐microbial liquid soap is more effective than conventional liquid soaps in reducing the viability of six bacterial species and that this effect is both time and dose dependent. However, when the three soaps were compared for their ability to reduce microbial counts on the hands no differences were observed between the three products. For all three soaps, counts after washing sometimes went up and sometimes down when compared with pre‐wash counts. This was the case both when the soaps were used ‘normally’– that is, with great variation in the time taken, water and soap volumes used and method of washing and after a standardized, rigorous wash recommended in clinical situations. Furthermore, reduction in microbial counts from hands contaminated by handling raw meat was no greater for the anti‐microbial than for the conventional liquid soap.
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