Effects of temperature and sanitizer wash treatments on foodborne pathogen survival during storage of work-in-process fresh-cut Brassica vegetables.

چکیده اصلی

Work-in-process (WIP) ingredients, within the fresh-cut produce industry, are often washed, then held for varying lengths of time, prior to incorporating into finished products. The effects of sanitizer washing and storage temperature on the survival and growth of Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella enterica were evaluated on WIP broccoli stalk, Brussels sprout, and kale. WIP produce was inoculated with pathogen cocktails (ca. 8 log CFU/ml), which were untreated or washed with water, free chlorine (ca. 100 ppm), or peracetic acid (PAA, ca. 80 ppm). Following storage at 4, 8, or 12 °C for 7 days, pathogen populations and indigenous microbiota were enumerated. Results showed that at 4 °C, populations declined or remained stable during the 7-day storage period but increased by up to ca. 3 log CFU/g at 12 °C, particularly for E. coli O157:H7 and S. enterica. Sanitizer washing reduced initial pathogen populations, with PAA generally producing greater immediate reductions than chlorine. However, sanitizer washing occasionally resulted in higher growth, particularly for L. monocytogenes, at elevated temperatures. In addition, indigenous microbiota often grew significantly faster on PAA-washed samples than on unwashed controls (e.g., mesophile population growth at 4 °C after 7-days' storage was 1.59 vs. 0.51, 0.96 vs. -0.27, and 1.61 vs. 0.71 log CFU on PAA vs. unwashed broccoli stalk, Brussels sprout, and kale, respectively). These results indicate that sanitizer washing provides only short-term reductions of microbial growth, highlighting temperature control at ≤4 °C as the most critical intervention for ensuring the microbial safety of WIP brassica vegetables.

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