Purpose: To advise consumers on food preparation practices that could affect the risk of contamination in the kitchen, studies were conducted that monitored the fate of bacterial pathogens on fresh-cut produce items that were subjected to brushing, peeling, grating, or cutting using common kitchen utensils.
Methods: GFP-labeled Escherichia coli O157:H7 and Salmonella spp. were spot-inoculated (50-150 µl of a 6-7 log CFU/ml inoculum) onto cantaloupe, honeydew melon, carrot, or celery prior to brushing, peeling, cutting, or grating. Bacterial enumeration or detection by enrichment culture was conducted on the utensils as well as the brushed or peeled produce items. The potential to contaminate non-contaminated produce items subsequently used with the contaminated utensil was also evaluated.
Results: Removal of bacterial pathogens by brushing of contaminated cantaloupes, honeydew melons, and carrots ranged from 0.1-0.6, 1.4-3.0, and 0.7-2.8 log CFU/100 g, respectively. Peeling carrots and celery led to pathogen losses ranging from 2.1-3.2 and 2.0-2.8 log CFU/100 g, respectively. A scouring pad used to brush produce items led to the highest incidence of contamination (57 positive of 89 items tested) whereas the nylon brush was the least likely to be contaminated (7 positive of 120 items tested). Transfer of bacterial pathogens to graters occurred 100% of the time but their transfer to knives ranged from 40% for tomatoes to 3% for cantaloupes. Contaminated knives and graters consistently transferred the pathogens to seven consecutive tomatoes or carrots being cut or grated whereas contaminated polyester-bristle brushes did not transfer the pathogens to carrots subsequently brushed.
Significance: In quantifying the cross-contamination risk associated with various steps in the food preparation process, the data collected in this study will aid risk management efforts in both home and food service kitchens.