Evaluation of Potential Impacts of Free Chlorine during Washing of Fresh-Cut Leafy Greens on Escherichia coli O157:H7 Cross-Contamination and Risk of Illness

Journal Article · 15 September 2021 · Risk Analysis

DOI: https://doi.org/10.1111/risa.13818 · OSTI ID:1905015

Mokhtari, Amir ^[1]; Pang, Hao  ^[2]; Santillana Farakos, Sofia ^[2]; Davidson, Gordon R. ^[2]; Williams, Elizabeth Noelia ^[2]; Van Doren, Jane M. ^[2]

---

1. U.S. Food and Drug Administration (FDA), College Park, MD (United States). Center for Food Safety and Applied Nutrition; OSTI
2. U.S. Food and Drug Administration (FDA), College Park, MD (United States). Center for Food Safety and Applied Nutrition

Addition of chlorine-based antimicrobial substances to fresh-cut leafy green wash water is done to minimize microbial cross-contamination during processing. We developed the FDA Leafy Green Risk Assessment Model (FDA-LGRAM) to quantify the impact of free chlorine concentration in wash water during fresh-cut lettuce processing on the extent of water-mediated cross-contamination between shredded lettuce and the associated risk of illness due to exposure to Escherichia coli O157:H7. At different contamination prevalence and levels of E. coli O157:H7 on incoming lettuce heads, the model compared the predicted prevalence of contaminated fresh-cut lettuce packages and the risk of illness per serving between: (1) a scenario where fresh-cut lettuce was packaged without washing; and (2) scenarios involving washing fresh-cut lettuce with different levels of free chlorine (0 ppm, 5 ppm, 10 ppm, 15 ppm, and 20 ppm) prior to packaging. Our results indicate that the free chlorine level in wash water has a substantial impact on the predicted prevalence of contaminated fresh-cut lettuce packages and the risk of illness associated with E. coli O157:H7 in fresh-cut lettuce. Results showed that the required level of free chlorine that can minimize water-mediated cross-contamination and reduce the corresponding risk of illness depended on contamination prevalence and levels of E. coli O157:H7 on incoming lettuce heads. Our model also indicated that the pathogen inactivation rate in wash water via free chlorine was a key model parameter that had a significant impact on the extent of cross-contamination during washing and the predicted associated risk of illness.

• Research Organization: Oak Ridge Institute for Science and Education (ORISE), Oak Ridge, TN (United States)
• Sponsoring Organization: U.S. Food and Drug Administration (FDA); USDOE Office of Science (SC)
• Grant/Contract Number: SC0014664
• OSTI ID: 1905015
• Journal Information: Risk Analysis, Journal Name: Risk Analysis Journal Issue: 5 Vol. 42; ISSN 0272-4332
• Publisher: WileyCopyright Statement
• Country of Publication: United States
• Language: English