Lethality of high-pressure carbon dioxide on Shiga toxin-producing Escherichia coli, Salmonella and surrogate organisms on beef jerky

Danielle M Schultze; Ricardo Couto; Feral Temelli; Lynn M McMullen; Michael Gänzle

doi:10.1016/j.ijfoodmicro.2020.108550

Lethality of high-pressure carbon dioxide on Shiga toxin-producing Escherichia coli, Salmonella and surrogate organisms on beef jerky

Int J Food Microbiol. 2020 May 16:321:108550. doi: 10.1016/j.ijfoodmicro.2020.108550. Epub 2020 Feb 5.

Authors

Danielle M Schultze¹, Ricardo Couto¹, Feral Temelli¹, Lynn M McMullen¹, Michael Gänzle²

Affiliations

¹ University of Alberta, Department of Agricultural, Food and Nutritional Science. 4-10 Agriculture/Forestry Centre, Edmonton, Alberta T6G 2P5, Canada.
² University of Alberta, Department of Agricultural, Food and Nutritional Science. 4-10 Agriculture/Forestry Centre, Edmonton, Alberta T6G 2P5, Canada. Electronic address: mgaenzle@ualberta.ca.

PMID: 32058874
DOI: 10.1016/j.ijfoodmicro.2020.108550

Abstract

Low water activity (a_W) foods permit the survival of low-infectious dose pathogens including Escherichia coli and Salmonella. Desiccation of non-heat resistant E. coli and Salmonella enterica increases their heat resistance; therefore, alternative methods are necessary to ensure the safety of low a_W foods. High-pressure carbon dioxide (HPCD) reduced microbial contaminants in high a_W foods. This study aimed to identify HPCD conditions that reduce pathogenic E. coli and Salmonella in low a_W conditions. Four strains of Shiga toxin-producing E. coli (STEC) and one strain of enteropathogenic E. coli were treated as a cocktail, and five strains of Salmonella were treated individually. The suitability of E. coli AW1.7, Pediococcus acidilactici FUA 3072, Enterococcus faecium NRRL B-2354 and Staphylococcus carnosus R6 FUA 2133 as surrogate organisms was evaluated. Treatments were validated in beef jerky. Samples were equilibrated to a_W 0.75 and treated with heat, HPCD or pressurized N₂. Treatment of desiccated E. coli AW1.7 and the STEC cocktail with dry gaseous CO₂ (5.7 MPa and 65 °C) did not reduce cell counts; however, treatment with gaseous CO₂ saturated with water reduced cell counts of all strains of E. coli. Treatment of beef jerky inoculated with E. coli and Salmonella with saturated gaseous CO₂ resulted in >5-log reductions for all strains. E. faecium NRRL B-2354 and S. carnosus R6 were suitable surrogates for Salmonella on beef jerky treated with HPCD. Treatment of beef jerky with water-saturated gaseous CO₂ was more effective than treatment with supercritical CO₂ or treatments with N₂ at the same temperature and pressure. Overall, the treatment of low a_W foods with water-saturated gaseous HPCD can meet industry standards by achieving a >5-log reductions of E. coli and Salmonella. Additionally, surrogate organisms representing pathogenic E. coli and Salmonella have been validated.

Keywords: Beef jerky; Enterohaemorrhagic E. coli; High pressure carbon dioxide; Meat safety; Salmonella; Verotoxin.

MeSH terms

Animals
Carbon Dioxide / pharmacology*
Cattle
Food Microbiology
Food, Preserved / analysis
Food, Preserved / microbiology*
Pasteurization / methods
Red Meat / microbiology*
Salmonella / drug effects*
Shiga-Toxigenic Escherichia coli / drug effects*
Water / analysis

Substances

Water
Carbon Dioxide