Fate of Listeria monocytogenes, Salmonella spp., and Shiga toxin-producing Escherichia coli on slices of an all-beef soppressata during storage

Authors: Luchansky, John; Shane, Laura; Osorio, Manuela; Vinyard, Bryan; Shoyer, Brad; CAMPANO, STEPHEN - Hawkins, Inc; Porto-Fett, Anna

Submitted to: Foods
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/8/2023
Publication Date: 5/11/2023
Citation: Luchansky, J.B., Shane, L.E., Osoria, M., Vinyard, B.T., Shoyer, B.A., Campano, S.G., Porto Fett, A.C. 2023. Fate of Listeria monocytogenes, Salmonella spp., and Shiga toxin-producing Escherichia coli on slices of an all-beef soppressata during storage. Foods. https://doi.org/10.3390/foods12101954.
DOI: https://doi.org/10.3390/foods12101954

Interpretive Summary: Soppressata is a globally-recognized, well-liked, Mediterranean-type, dry-cured, salami made from coarsely ground leaner cuts of pork. It is also one of the most preferred, widely distributed, and trendiest salumi included on charcuterie boards. The longstanding demand for high-quality and locally-sourced artisanal meats such as soppressata, and in more recent years especially for all-beef products formulated to accommodate individuals on a restrictive diet, has served as a justification to scientifically validate the safety and to certify the shelf life of all-beef soppressata and related products. Thus, the primary objective of this study was to determine if an all-beef soppressata would allow for survival or support the (out)growth of L. monocytogenes, Salmonella spp., or STEC during storage. In brief, commercial soppressata purchased from an online vendor was sliced, placed into bags, separately inoculated with multi-strain cocktails of each of the above-mentioned food borne pathogens, vacuum-sealed, and stored at refrigeration (4°C) or ambient (20°C) temperature. Our results confirmed that levels of all three pathogens decreased by ca. 150 to 1200 cells per slice during storage at 4°C or by ca. =2000 cells per slice during storage at 20°C. These data affirmed that slices of the commercial-produced soppressata selected for this study did not provide a favorable environment for either survival or outgrowth of surface-inoculated cells of L. monocytogenes, Salmonella spp., or STEC during storage.

Technical Abstract: Cells of Listeria monocytogenes, Salmonella spp., or Shiga toxin-producing Escherichia coli (STEC) were inoculated onto slices of an all-beef soppressata (ca. pH 4.97 and aw 0.854) and viability was monitored during storage at 4°C and 20°C. After placing a single slice of soppressata within a nylon-polyethylene-vinyl bag, a 25-µL portion per side (ca. 4.0 log CFU/slice) of a rifampicin-resistant (100 mg/ml) multi-strain cocktail of either L. monocytogenes (5 strains), Salmonella spp. (5 strains), or STEC (8 strains) was introduced into each bag with the aid of a micropipette. When vacuum sealed slices of soppressata were stored at 4°C or 20°C for 90 days, levels of all three pathogens decreased by ca. 2.2 to 3.1 or by ca. =3.3 log CFU/slice, respectively. When pathogen levels decreased to below detection (=1.18 log CFU/slice) by direct plating, it was more likely to recover all three target pathogens by enrichment from soppressata following storage at 4°C compared to 20°C. Thus, slices of the commercial-produced soppressata selected for this study did not provide a favorable environment for either survival or outgrowth of surface-inoculated cells of L. monocytogenes, Salmonella spp., or STEC during storage.