Behavior of Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella enterica During Storage of Work-in-Process Fresh-Cut Carrot and Onion as Affected by Sanitization and Storage Temperature

Fresh-cut produce operations often generate work-in-process (WIP) ingredients that have undergone peeling, cutting, washing, etc., and are then subjected to temporary holding, prior to packaging, creating conditions that may favor pathogen survival and growth. The objective of this study was to evaluate the survival of Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enterica, and native microbiota on WIP fresh-cut carrot and yellow onion treated with deionized water, sodium hypochlorite (NaOCl, >10 ppm free chlorine), or peracetic acid (PAA, 80 ppm) and held at 4, 8, or 12 °C for up to seven days. Pathogen behavior was strongly influenced by storage temperature and commodity matrix. At 4 °C, E. coli O157:H7 and S. enterica populations generally declined or remained stable. Conversely, at 8 °C and 12 °C, which were evaluated to simulate potential temperature-abuse scenarios, E. coli O157:H7 and S. enterica proliferated in unwashed samples but were often suppressed by chlorine and PAA. L. monocytogenes on carrot did not grow under any treatment or temperature, likely due to intrinsic antimicrobial compounds, while it persisted on onion and grew by 0.5-1.6 logs under temperature abuse. PAA often provided the greatest pathogen reductions on onion, although chlorine was more effective against E. coli O157:H7 on carrot. Native mesophilic or psychrotrophic bacteria, and yeast and mold populations, increased rapidly across all treatments and storage conditions, with PAA-washed samples often having the greatest growth rates. Overall, while sanitizer efficacy was commodity-dependent, strict temperature and holding time management emerged as the most critical factor in limiting pathogen growth. These findings underscore the necessity of an integrated management approach for WIP produce, although further validation under dynamic industrial conditions and mechanisms for the rapid regrowth of microbiota in PAA-washed samples warrant further investigations.