Peracetic acid efficacy against Salmonella is driven by temperature, bacterial concentration and serovar

Peracetic acid (PAA) is a widespread antimicrobial in food processing, yet its efficacy could be influenced by biological and environmental factors. The combined impact of the interactions of such factors remains largely unexplored. This study evaluated the efficacy of PAA against Salmonella by determining the minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC). Four Salmonella serovars (Enteritidis, Typhimurium, Newport, and Kentucky), represented by three strains each, were evaluated using a broth microdilution approach with inoculum levels ranging from 3 to 8 log₁₀ CFU/mL and temperatures of 4, 26, and 37°C. Statistical analysis was conducted using cumulative link mixed effects models fitted to MIC and MBC responses. The present study shows that PAA efficacy has a complex function, which was modeled not only by a single factor, but after the interaction of bacterial load, temperature, and serovar. Bacterial concentration was a key factor determining susceptibility values, which highlighted the importance of this factor when designing interventions. Lower temperatures reduce PAA efficacy systematically (at 4°C), which poses a significant challenge for interventions that use cold temperatures. Serovar differences were observed, which reinforces the evidence of uneven antimicrobial susceptibility among serovars. This study shows that probabilistic modeling could be a useful tool for decision making by providing benchmarks for optimizing PAA applications in either future research or industry applications. Ultimately, this work shows that PAA efficacy against Salmonella is variable but could be explained by the biological and environmental conditions encountered in food processing.