Control of Listeria monocytogenes in Nitrite-Reduced Mediterranean Dry-Fermented Sausages Using Two Bacteriocinogenic Pediococcus acidilactici Strains

Abstract Biopreservation has great potential as a novel strategy to increase the shelf-life and safety of foods, especially fermented ones. In this study, two strains of pediocin-producing Pediococcus acidilactici (MP14 and B-LC-20) were assayed as protective cultures against Listeria monocytogenes for Mediterranean dry-fermented sausages. P. acidilactici MP14 was isolated from artisanal sausages, while P. acidilactici B-LC-20 is a commercially available starter. Previous in vitro assays were conducted to assess the effect of temperature (22 and 12 °C), nitrate/nitrite (0 and 75 mg/kg each) and L. monocytogenes strain on the antilisterial activity of both pediococci. Among these factors, temperature had the greatest effect, suggesting better conditions for bacteriocin production at 22 °C, while no influence of nitrate/nitrite was observed. No interactions among the factors under study were shown. Antilisterial activity was further tested in fermented sausages inoculated with L. monocytogenes and ripened during 28 days. Both pediococci showed good implantation in the sausage environment and provided L. monocytogenes inhibition already at fermentation, preventing the growth of the pathogen from the early stages of production. One log cfu/g inhibition of L. monocytogenes was obtained at the end of ripening in the sausages inoculated with pedicocci, in comparison with the initial levels. The final numbers of the pathogen were 2-log cfu/g lower in pediocci-inoculated sausages compared to those inoculated with a non-bacteriocinogenic Latilactobacillus sakei starter. The final Listeria counts were not influenced by nitrate/nitrite, although a certain trend to lower numbers was observed. The antilisterial activity provided by P. acidilactici MP14 was similar to that of the commercial starter, showing potential as a new protective culture for the meat industry.