Viability of listeria monocytogenes and salmonella spp. on slices of a german-style bologna containing blends of organic acid salts during storage at 4 or 12C

Authors: Luchansky, John; CAMPANO, STEPHEN G. - Hawkins, Inc; RIEKER, MARCUS - Riekers Meats; MAHONEY, CAROLINE - Riekers Meats; Vinyard, Bryan; Shane, Laura; Shoyer, Brad; Osorio, Manuela; Porto-Fett, Anna

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/24/2022
Publication Date: 12/1/2022
Citation: Luchansky, J.B., Campano, S., Rieker, M., Mahoney, C., Vinyard, B.T., Shane, L.E., Shoyer, B.A., Osoria, M., Porto Fett, A.C. 2022. Viability of listeria monocytogenes and salmonella spp. on slices of a german-style bologna containing blends of organic acid salts during storage at 4 or 12C. Journal of Food Protection. 86(1):100019. https://doi.org/10.1016/j.jfp.2022.100019.
DOI: https://doi.org/10.1016/j.jfp.2022.100019

Interpretive Summary: Processors of ready-to-eat (RTE) red meat and poultry products have several food grade chemicals they can use to control pathogens in/on meats. The most widely used chemicals for this purpose are organic acids, and especially lactic acid and acetic acid, based on efficacy, availability, ease of use, and price point. These chemicals have been used extensively as ingredients for delicatessen-type meats to control foodborne pathogens such as Listeria monocytogenes and Salmonella spp. However, given the number and magnitude of recalls and illnesses still being caused by contamination of deli meats with these pathogens, further studies are warranted to develop additional organic acid blends for pathogen control and/or shelf-life extension. In this study, we validated the efficacy of different blends and levels of potassium lactate, potassium acetate, and sodium diacetate to control L. monocytogenes (Gram-positive bacterium) and a Gram-negative pathogen, namely Salmonella spp., on slices of a German-style bologna formulated specifically for this study. In the absence of antimicrobials added to the formulation, L. monocytogenes numbers increased by about 250,000 or 1,000,000 cells per bologna slices stored at 4C for up to 90 days or 12C for up to 30 days, respectively. Cells of Salmonella also increased by about 1,000,000 cells per slice at 12C after 30 days but decreased by about 100 cells per slice at 4C after 90 days when antimicrobials were not added to the formulation. When antimicrobials were included in the formulation, levels of both pathogens decreased by about 10 to 250 cells per slice during storage at 4C. When inoculated product was stored at 12C, levels of Salmonella decreased by about 10 to 100 cells per slice, whereas levels of L. monocytogenes increased by 2,500 cells per slice. These data show that blends of salts of lactic or acetic acid were effective for controlling cells of L. monocytogenes and Salmonella spp. on slices of bologna during refrigerated storage.

Technical Abstract: Viability of cells of Listeria monocytogenes or Salmonella spp. was quantified on slices of a German-style bologna manufactured by a local butcher to contain no added antimicrobials or to include 0.9% or 1.3% of a blend of potassium acetate and sodium diacetate (K-Ace) or 2.5% of a blend of potassium lactate and sodium diacetate (K-Lac) as ingredients. After slicing (ca. 7.1 cm L x 6.7 cm W, ca. 0.5 cm thick, ca. 22.4 g each), a single slice of bologna was placed into a nylon polyethylene bag and surface inoculated with 250 ul per side of a five-strain mixture of either cells of L. monocytogenes or Salmonella spp. to achieve an initial level of ca. 3.5 to 4.0 log CFU/slice. The packages were vacuum-sealed and then stored at 4 or 12degC for 90 and 30 days, respectively. Without antimicrobials added to the formulation, L. monocytogenes numbers increased by ca. 5.4 and 6.0 log CFU/slice at both 4 and 12degC, respectively. Likewise, levels of Salmonella also increased by ca. 6.0 log CFU/slice at 12degC in the absence of added antimicrobials; however, levels of this pathogen decreased by ca. 1.7 log CFU/slice at 4degC. With inclusion of 0.9% or 1.3% K-Ace or 2.5% K-Lac in the bologna formulation, levels of L. monocytogenes decreased by ca. less than 0.7 log CFU/slice at 4°C, whereas levels of Salmonella decreased by ca. 1.6 to 2.3 log CFU/slice. At 12degC, and regardless of which antimicrobial blend was used, levels of L. monocytogenes remained relatively unchanged after 18 days of storage. Thereafter, pathogen levels increased by ca. less than 3.4 log CFU/slice on product containing 0.9% K-Ace or 2.5% K-Lac but remained relatively unchanged on slices formulated with 1.3% K-Ace. For Salmonella, in the presence of 0.9% or 1.3% K-Ace or 2.5% K-Lac pathogen levels decreased by ca. less than 0.7 log CFU/slice at 12degC after 30 days. Our data validate that inclusion of K-Ace (0.9% or 1.3%) or K-Lac (2.5%) as ingredients is effective for controlling L. monocytogenes and Salmonella on slices of bologna during refrigerated storage.