Department of Food Science, Rutgers University, 65 Dudley Road, New Brunswick, New Jersey 08901-8520, USA.
J Food Prot. 2013 Sep;76(9):1530-8. doi: 10.4315/0362-028X.JFP-13-098.
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.
食品加工环境和家庭厨房中食物与表面之间的交叉污染可能在食源性疾病传播中发挥重要作用。本研究通过不同的交叉污染方向、表面类型、食品类型和干燥时间/水分水平的情景，量化了各种新鲜切割农产品与常见厨房表面（陶瓷、不锈钢、玻璃和塑料）之间的交叉污染率。在涉及芹菜、胡萝卜和西瓜的转移情景中，使用了耐 rifampin 的五株沙门氏菌鸡尾酒，在涉及生菜的转移情景中，使用了耐 rifampin 的五株大肠杆菌 O157:H7 鸡尾酒。将农产品或表面优惠券放入充满缓冲液的滤袋中，分别进行匀浆或按摩，以回收细胞。将得到的溶液在 0.1%蛋白胨中进行连续稀释，并在含有 80μg/ml rifampin 的胰蛋白酶大豆琼脂和含有 80μg/ml rifampin 的亚硫酸铋琼脂上对沙门氏菌或含有 80μg/ml rifampin 的山梨醇麦康凯琼脂上对大肠杆菌 O157:H7 进行表面划线。当食品接触面刚被接种时，大量（>90%）接种物几乎总是转移到切割的农产品上。如果让接种的食品接触面干燥 1 小时，通常胡萝卜和西瓜的平均转移量>90%，但芹菜和生菜的转移量从<1 到∼70%不等。与刚接种的胡萝卜或西瓜相比，刚接种的芹菜或生菜转移的细菌数量较少（<2 到∼25%的接种物）。干燥 1 小时后，从接种的芹菜、胡萝卜和生菜转移的速率<0.01 到∼5%，从接种的西瓜转移的速率<1 到∼5%。表面水分和转移方向对微生物转移率的影响最大。
