Quantifying cross-transfer dynamics of planktonic and biofilm Listeria monocytogenes and disinfection efficacy in ice cream processing environments

The food processing environment is a primary source of Listeria monocytogenes contamination in ice cream. This study aimed to investigate the cross-contamination of planktonic and biofilm-associated L. monocytogenes in ice cream processing settings and evaluate the impact of peracetic acid (PAA) spray treatment on their transfer. Results showed that PAA effectively reduced viable L. monocytogenes counts on stainless steel surfaces but failed to achieve complete eradication. A negative correlation was observed between PAA treatment duration and both the single-contact transfer amount from food-contact surfaces to ice cream and the residual amount after multiple contacts, with transfer amounts generally decreasing during repeated contacts. In reverse contamination, inoculum size significantly affected transfer amount but had no significant overall effect on transfer rate. Incubation temperature influenced the maximum viable count of mature L. monocytogenes biofilms, and dynamic transfer mode facilitated biofilm cell transfer more than static mode. The Logistic model effectively described biofilm transfer kinetics within a specific timeframe ( R 2 adj: 0.82-0.93; RMSE < 0.2). Collectively, these findings highlight the critical importance of controlling initial L. monocytogenes contamination and provide valuable references for quantitative microbial risk assessment of ice cream. • The transfer and residual status of L. monocytogenes differ across different scenarios. • L. monocytogenes can also transfer from ice cream to food-contact surfaces. • The Logistic model could describe the transfer behavior of biofilm cells. • Controlling the initial contamination of L. monocytogenes is crucial for reducing cross-contamination.