Effect of nisin, EDTA, and abuse temperature on the growth of Salmonella Typhimurium in liquid whole egg during refrigerated storage

Authors: Bermudez-Aguirre, Luz; Niemira, Brendan

Submitted to: Food Research International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/9/2023
Publication Date: 10/10/2023
Citation: Bermudez-Aguirre, L.D., Niemira, B.A. 2023. Effect of nisin, EDTA, and abuse temperature on the growth of Salmonella Typhimurium in liquid whole egg during refrigerated storage. Food Research International. 174. https://doi.org/10.1016/j.foodres.2023.113568.
DOI: https://doi.org/10.1016/j.foodres.2023.113568

Interpretive Summary: Pathogens such as Salmonella have been reported in pasteurized liquid whole egg (LWE) and egg products because of some heat-resistant strains or post-contamination. The effect on the growth of Salmonella of natural antimicrobials alone or in combination with EDTA added to LWE was studied under two different refrigeration temperatures, 7°C (retail temperature) and 10°C (retail abuse temperature). pH and color were evaluated during storage. The results showed that those samples of LWE stored at 7°C had a decay in the number of cells that was increased for the action together of natural antimicrobials and EDTA. Meanwhile, those samples at higher temperatures (10°C) showed a constant growth rate of Salmonella during the storage regardless of the use of antimicrobials. The pH and color remained unchanged after 31 days of storage. Using natural antimicrobials, EDTA, and 7°C represents an option to minimize the risk of Salmonella in pasteurized LWE during storage.

Technical Abstract: Salmonella spp. can be present in pasteurized liquid egg products because of its heat resistance or post-processing contamination representing a food safety risk. The effect of 1000 IU nisin/ml plus 20 mM EDTA, two refrigerated temperatures (7°C and 10°C), and two inoculation levels (10^3 and 10^5 cfu/ml) were studied in the growth of S. Typhimurium in pasteurized liquid whole egg (LWE). Two mathematical models were used to fit the microbial curves. Physico-chemical characteristics of LWE, such as pH and color, were assessed for 31 days at the two storage temperatures, and no significant changes (p < 0.05) were observed for most of the samples. Results showed the significant impact of temperature on microbial growth. Samples kept at 7°C showed the decay of microbial cells during storage; meanwhile, the effect at 10°C was shown as fast growth. The combination of nisin plus EDTA and 7°C accelerated the decay of microbial cells during the storage showing a synergistic effect. The Weibull model described the decline of cells during the shelf-life. Meanwhile, the logistic model fitted the growth of Salmonella in LWE at 10°C. Adding these additives to LWE, combined with the correct temperature during pasteurization and adequate conditions during the cold chain, can minimize the food safety risk related to Salmonella.