Modeling the Growth of Salmonella on Sliced Cucumbers as a Function of Temperature and Relative Humidity

Abstract: Recent multistate outbreaks of salmonellosis linked to fresh cucumbers underscore the importance of understanding Salmonella behavior on cucumbers under different storage conditions. No validated models that describe the impact of environmental factors on the growth of Salmonella on sliced cucumbers currently exist. This study developed mathematical models to predict the growth of Salmonella on sliced cucumbers at different temperature and relative humidity (RH) conditions. Sliced cucumbers were inoculated with a four-strain cocktail of Salmonella and placed in desiccators containing a saturated salt solution to create controlled RH environments (∼15, 50, and 100% RH) at 7, 14, and 21°C for up to 120 h. Predictive models were developed by using the Baranyi and Roberts equation as a primary model, and estimated kinetic parameters were fitted into a square root (or Ratkowsky) equation for secondary models. The maximum growth rates for Salmonella on sliced cucumbers depended on temperature but not RH. The square root model for Salmonella growth was √μ= 0.0297 × (T - 6.5185), with a high R2 value (0.98). The models in this study will be useful for future microbial risk assessments and predictions of Salmonella behavior in the cucumbers to manage the risk of Salmonella on sliced cucumbers.