Cross-contamination between foods and surfaces in food processing environments and home kitchens may play a significant role in foodborne disease transmission. This study quantifies the cross-contamination rates between a variety of fresh-cut produce and common kitchen surfaces (ceramic, stainless steel, glass, and plastic) using scenarios that differ by cross-contamination direction, surface type, produce type, and drying time/moisture level. A five-strain cocktail of rifampin-resistant Salmonella was used in transfer scenarios involving celery, carrot, and watermelon, and a five-strain cocktail of rifampin-resistant Escherichia coli O157:H7 was used in transfer scenarios involving lettuce. Produce or surface coupons were placed in buffer-filled filter bags and homogenized or massaged, respectively, to recover cells. The resulting solutions were serially diluted in 0.1% peptone and surface plated onto tryptic soy agar with 80 μg/ml rifampin and bismuth sulfite agar with 80 μg/ml rifampin for Salmonella or sorbitol MacConkey agar with 80 μg/ml rifampin for E. coli O157:H7. When the food contact surface was freshly inoculated, a high amount (>90%) of the inoculum was almost always transferred to the cut produce item. If the inoculated food contact surfaces were allowed to dry for 1 h, median transfer was generally >90% for carrots and watermelon but ranged from <1 to ~70% for celery and lettuce. Freshly inoculated celery or lettuce transferred more bacteria (~2 to ~25% of the inoculum) compared with freshly inoculated carrots or watermelon (approximately <1 to 8%). After 1 h of drying, the rate of transfer from inoculated celery, carrot, and lettuce was <0.01 to ~5% and <1 to ~5% for watermelon. Surface moisture and direction of transfer have the greatest influence on microbial transfer rates.
Quantifying Transfer Rates of Salmonella and Escherichia coli O157:H7 between Fresh-Cut Produce and Common Kitchen Surfaces
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DANE A. JENSEN, LORETTA M. FRIEDRICH, LINDA J. HARRIS, MICHELLE D. DANYLUK, DONALD W. SCHAFFNER; Quantifying Transfer Rates of Salmonella and Escherichia coli O157:H7 between Fresh-Cut Produce and Common Kitchen Surfaces. J Food Prot 1 September 2013; 76 (9): 1530–1538. doi: https://doi.org/10.4315/0362-028X.JFP-13-098
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