Radio frequency plus heat for in-shell egg pasteurization

Authors: Bermudez-Aguirre, Luz; Sites, Joseph; Carter, Joshua; Niemira, Brendan

Submitted to: Innovative Food Science and Emerging Technologies
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/2/2024
Publication Date: 10/5/2024
Citation: Bermudez-Aguirre, L.D., Sites, J.E., Carter, J.R., Niemira, B.A. 2024. Radio frequency plus heat for in-shell egg pasteurization. Innovative Food Science and Emerging Technologies. 98:103834. https://doi.org/10.1016/j.ifset.2024.103834.
DOI: https://doi.org/10.1016/j.ifset.2024.103834

Interpretive Summary: The presence of foodborne pathogens in different commodities represents a food safety risk. A novel technology named radio frequency plus heat was studied to inactivate Salmonella cells inoculated inside eggs. The eggs were processed with the radio frequency pasteurizer and evaluated for the presence of alive, sub-lethally injured and recovered cells after processing and after the storage of eggs for a week under refrigerated conditions. Furthermore, the quality attributes for eggs were evaluated after the processing. The pasteurization standard of 5 – log reduction was achieved using this novel technology, which means 99.999% of the inoculated cells were inactivated. The presence of sub-lethally injured cells or cell recovery after processing was not observed. The quality of radio frequency – processed eggs remained almost similar to raw eggs. This technology is an option to ensure the food safety of eggs without compromising the egg quality.

Technical Abstract: Less than 3% of the eggs in the United States are sold pasteurized because of the long thermal process (~ 60 min). This research studied the inactivation of Salmonella Typhimurium in in-shell eggs using radio frequency (RF), evaluating quality, presence of sub-lethally injured cells (SLICs), and cell recovery (7°C). Eggs were inoculated inside with S. Typhimurium (10^5 CFU/egg) and processed with RF (40.68 MHz, 35 W, 4.5 min) followed by hot water spray (HWS 56.7°C, 20 min). The studied quality attributes were yolk color, Haugh unit, yolk index, shell breakage strength, yolk and albumen pH, and albumen degradation. ANOVA one–way was used to find significant differences (' alpha = 0.05). RF plus HWS was able to pasteurize the eggs after 24.5 min (5-log reduction). No SLICs were detected in any of the samples, and cells did not recover after 7 days of storage (Limit of detection < 1 log CFU/g). Most quality attributes were like the control eggs. Albumen degradation showed a significant difference (p < 0.05) after processing. RF represents a potential option to ensure the safety of in-shell eggs, preserving their quality.