Quantifying Escherichia coli contamination in milling equipment during lab-scale milling operations

Background and Objectives Cross-contamination of foodborne pathogens from equipment to food is a food safety concern. The objective of this study was to quantify the amount of Escherichia coli contamination in mill equipment after milling inoculated and noninoculated wheat in single milling run. Findings Mill equipment used for milling inoculated kernels contained substantial amounts of E. coli. The hoppers, feeders, rollers, and break system sifter surfaces had higher E. coli counts compared to other surfaces sampled (2.0-3.6 log CFU/100 cm(2)). Surfaces from the break system of the mill had higher counts in general compared to the sizing/reduction system. The majority of equipment surfaces had nonquantifiable E. coli counts after milling noninoculated kernels indicating cross-contamination of E. coli from contaminated equipment to mill fractions. Conclusions The findings indicate that E. coli could easily transfer from wheat kernels into milling equipment and vice-versa. This demonstrates that mill equipment is a viable route for E. coli contamination during milling and that cleaning and sanitation practices could be focused on the surfaces mentioned in this study to reduce cross-contamination risk. Significance and Novelty The findings from this study could help determine surfaces where microbial contamination could accumulate, which could improve mill cleaning and sanitation practices.