Survival of Listeria monocytogenes and Salmonella Typhimurium in Pepperoni With Reduced Salt and Sodium Nitrite Levels, and Sublethal Thermal Treatments

Authors

• Shannon Heapes, Department of Food Chemistry and Technology
• Victoria Caballero, Sustainability and Health Research Hub
• Jesus Frias, Research Hubs
• Bradley Afanda, Department of Food Chemistry and Technology
• Martin Danaher, Department of Food Chemistry and Technology
• Joseph P. Kerry, School of Food & Nutritional Sciences
• Geraldine Duffy, Department of Food Chemistry and Technology

ORCID

• Jesus Frias: 0000-0001-5424-5167

Abstract

There is increasing pressure to reduce sodium nitrite and salt levels in processed and fermented meats in response to consumer demands and updated legislation. However, such reductions may impact pathogen control. In this study, the survival of Listeria monocytogenes and Salmonella Typhimurium was evaluated in pepperoni produced with reduced salt and sodium nitrite levels, with or without an enhanced postfermentation thermal treatment. Pepperoni batters with formulations varying in sodium nitrite (50–150 ppm) and salt (1.4%–2.5%), were inoculated with cocktails of L. monocytogenes or S. Typhimurium (~log₁₀ 4–6 CFU g⁻¹), subjected to a postfermentation thermal treatment (53.5°C × 61 min; 61°C × 40 min; 64°C × 20 min), and dried to a target water activity of 0.91 or 0.94. Overlay plating was used to enumerate both pathogens, allowing recovery of sublethally injured cells, and residual nitrite was also measured. In the standard formulation reductions of log₁₀ 4.47 CFU g⁻¹ for L. monocytogenes and log₁₀ 4.18 CFU g⁻¹ for S. Typhimurium were observed from prefermentation to endpoint. Formulation 1a, which differed from the standard formulation only in having a lower sodium nitrite level (50 ppm), showed endpoint reductions of log₁₀ 4.21 CFU g⁻¹ for L. monocytogenes and log₁₀ 4.58 CFU g⁻¹ for S. Typhimurium. A similar trend was observed in formulations with reduced sodium nitrite and salt levels. However, formulations subjected to the elevated thermal treatment (61°C × 40 min) showed greater endpoint reductions in both L. monocytogenes and S. Typhimurium compared with formulations processed at 53.5°C × 61 min. Residual nitrite levels at endpoint were well below legal limits across all recipes, reflecting extensive nitrite depletion during fermentation, heating, and drying. These findings demonstrate that pepperoni can be manufactured safely with reduced sodium nitrite and salt when a validated, postfermentation heat treatment is incorporated within a multihurdle system, supporting the feasibility of reformulation under current consumer and regulatory pressures.

Keywords

fermented meats 2, Listeria monocytogenes 4, pepperoni 3, Salmonella Typhimurium 5, salt reduction, sodium nitrite reduction 6

DOI Link

10.1111/jfs.70091

Publication Date

2026-01-01

Publication Title

Journal of Food Safety

Volume

46

Issue

5

ISSN

0149-6085

Deposit Date

2026-10-30

Funding

This project was funded by the Department of Agriculture, Food and the Marine (Dublin, Ireland) Through the Food Institutional Research Management (FIRM) Programme (project number 2019R452) and the Teagasc Walsh Scholarships Programme

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.

Additional Links

https://www.scopus.com/pages/publications/105049368082

Recommended Citation

Heapes, S., Caballero, V., Frias, J., Afanda, B., Danaher, M., Kerry, J., & Duffy, G. (2026) 'Survival of Listeria monocytogenes and Salmonella Typhimurium in Pepperoni With Reduced Salt and Sodium Nitrite Levels, and Sublethal Thermal Treatments', Journal of Food Safety, 46(5). Available at: 10.1111/jfs.70091