Seasoning containers as reservoirs of pathogenic Escherichia coli: Cross-contamination dynamics during yukhoe (Korean beef tartare) preparation.

This study investigated the role of seasoning containers as a critical hub for cross-contamination with pathogenic Escherichia coli during the preparation of yukhoe (Korean beef tartare). A survey of food handlers revealed inconsistent glove management practices and frequent contact between contaminated hands and seasoning containers. Based on these findings, simulation experiments were conducted to evaluate (i) the transfer of pathogenic E. coli from yukhoe to seasoning containers via artificial skin, latex glove, and PE glove, (ii) the survival of transferred bacteria on seasoning container surfaces, and (iii) the subsequent transfer back to yukhoe. In the presence of the yukhoe matrix containing 6.32 log CFU/g of pathogenic E. coli, transfer to simulated hand surfaces (artificial skin, latex glove, and PE glove) yielded populations of 4.72-5.01 log CFU/coupon. Subsequent transfer to polyethylene terephthalate (PET), a common material for seasoning containers, resulted in 3.75-4.09 log CFU/coupon, representing transfer rates of 11.4-15.5%. In contrast, without the yukhoe matrix, E. coli directly inoculated onto hand surfaces (5.96-6.63 log CFU/coupon) was transferred to PET surfaces at 3.66-5.04 log CFU/coupon, representing markedly lower transfer rates of only 1.1-4.7%. Survival analysis demonstrated that transferred pathogens could persist on container surfaces for extended periods, up to 35 days, with long-term persistence significantly enhanced by the presence of the yukhoe matrix. Crucially, qualitative enrichment revealed that sub-lethally injured cells remained viable at 5 °C throughout the 35-day storage period, even when populations fell below quantitative detection limits, posing a lasting, latent cross-contamination hazard. Finally, contaminated seasoning containers readily facilitated the transfer of high levels of E. coli back to yukhoe (>4 log CFU/g), regardless of glove material. This study provides quantitative evidence of bidirectional transfer and the prolonged survival of pathogenic E. coli on underappreciated seasoning containers. These findings advance our understanding of cross-contamination dynamics beyond primary food-contact utensils, offering a crucial scientific basis for improving hygiene practices associated with yukhoe and other raw beef dishes.