Modeling quality changes and Salmonella Typhimurium growth in storage for eggs pasteurized by radio frequency treatments

Authors: Bermudez-Aguirre, Luz; Niemira, Brendan

Submitted to: Food Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/19/2023
Publication Date: 1/21/2023
Citation: Bermudez-Aguirre, L.D., Niemira, B.A. 2023. Modeling quality changes and Salmonella Typhimurium growth in storage for eggs pasteurized by radio frequency treatments. Food Control. https://doi.org/10.1016/j.foodcont.2023.109638.
DOI: https://doi.org/10.1016/j.foodcont.2023.109638

Interpretive Summary: There is a need to understand how Salmonella can grow in eggs stored after antimicrobial treatements like radio frequency energy, and what those treatments do to the quality of the eggs. In this study, eggs were pasteurized with radio frequency treatments in less than 20 min. A high initial number of Salmonella cells was inoculated in the eggs to study the number of survivors and the possible microbial growth over refrigerated storage. Three different mathematical models were fitted to the growth curves. Each model showed a good fit and demonstrated that Salmonella can still multiply under refrigerated conditions in the unlikely event there are viable cells after processing. Changes in egg quality were also modeled and key shelf-life parameters were calculated. These mathematical models showed that the quality of radio frequency treated eggs is well preserved during the 5-week storage period. These results will help scale up the technology and support further commercializing of RF-treated eggs.

Technical Abstract: Salmonella Typhimurium 53647 was inoculated in eggs and inactivated with radio frequency (RF). Processing was conducted at 40.68 MHz, 35 W, 56.7°C, and 19.5 min. Control and RF-treated eggs were stored at 7.2 °C and 10°C, and the microbial and overall quality was assessed weekly for five weeks. Mathematical models were used to describe the growth of Salmonella and the quality degradation over time. The logistic, Gompertz, and Richards models accurately described the microbial growth in RF-treated eggs (R2 > 0.97). The weight loss was best described by zero-order kinetics and the Haugh unit by first-order kinetics. The Weibull equation described the behavior of albumen pH over storage. The degradation over time of the egg quality attributes was efficiently evaluated with the Global Stability Index (GSI). RF-treated eggs showed a better quality over time than control eggs based on the GSI values.