Fate of Listeria monocytogenes in diced onions, and celery, and Salmonella typhimurium in diced tomatoes, in different packaging systems during simulated commercial storage

Temperature is arguably the most important factor affecting microbial proliferation in fresh-cut produce. In this study, the growth responses of Listeria monocytogenes in diced onions and celery, and Salmonella typhimurium in diced tomatoes in modified atmosphere packages and snap-fit containers were examined using three fluctuating time/temperature scenarios for transport, retail storage and display. As expected, L. monocytogenes growth in diced onions and celery varied depending on the extent of temperature abuse, with the products stored under the profiles with the highest and intermediate temperature abuse showing significant growth (P < 0.05) in all packages. Salmonella typhimurium did not show any significant growth in diced tomatoes under the three temperature conditions considered in this study, regardless of the packaging systems. Overall, diced produce in high oxygen atmosphere showed reduced growth compared to other packaging systems. The primary growth parameters for L. monocytogenes in diced onions, and celery were estimate at 12, 16, and 23°C using the Baranyi growth model. The maximum growth rates for L. monocytogenes in both products were highest at 23°C, while the populations were highest at 12°C. The Ratkowsky root-square model was used to estimate the secondary growth parameters for L. monocytogenes in both products. Findings from this study will be particularly useful in assessing the risk associated with the consumption of these fresh-cut products.