Stress Tolerance Assays for Salmonella enterica: Methods for Evaluating Heat, Acidity, and Osmotic Resistance

Salmonella remains a leading cause of foodborne illness worldwide and imposes substantial public health and economic burdens, particularly due to its persistence in food production systems. This persistence is driven not only by antimicrobial resistance but also by adaptive survival strategies, including stress tolerance that allows the cells to endure sublethal and lethal stresses encountered across the farm-to-fork continuum. Quantitative characterization of these phenotypes is crucial for understanding pathogen survival dynamics and strain-specific variability, thereby improving food safety interventions and enhancing risk management in practical settings. This chapter describes a standardized in vitro assays for quantifying Salmonella stress tolerance to three major environmental stressors: heat, pH, and osmotic stress, with detailed procedures and troubleshooting notes. The protocols are designed to generate high-resolution data for the precise determination of growth kinetics, survival rate, and decimal reduction time across different stressor intensities and exposure durations. Taken together, these assays provide a practical framework for evaluating the effectiveness of heating, acidification, and salting in controlling Salmonella under conditions relevant to real-world food safety.