Purpose: The objective of this study was to develop a survival, growth, and death model for Salmonella in leafy greens in order to predict the growth and decline behaviors of the pathogen under non-isothermal time-temperature profiles.
Methods: Experimental data for the growth of Salmonella under different conditions and storage temperatures were retrieved from published studies, followed by development of three-phase linear model as primary growth model and square-root model as secondary model to calculate growth rate (μ) at different temperatures. Death data was also collected for storage temperature below 5°C. A total of 35 growth and 18 death curves were available from 16 published studies.
Results: The square-root model was fitted as μ = (0.20*(Temperature+0.57))2. Mean death rate at the temperature below 5°C was 0.014 log CFU/h. These models were validated using several dynamic time-temperature profiles for the supply chain of leafy greens. Variability was taken into consideration by calculating 95% confidence intervals. Based on statistical parameters, such as accuracy factor and bias factor, and acceptable prediction zone (APZ) analysis, the model predictions were found to be within acceptable range.
Significance: The results from this study will be useful for future microbial risk analyses and predictions of behavior of Salmonella in leafy green supply chain.