Inhibition of Listeria monocytogenes by bacteriocin-producing Pediococcus during the manufacture of fermented semidry sausage

Abstract

A bacteriocin-producing Pediococcus species inhibitory to Listeria monocytogenes was used to manufacture fermented semidry sausage. Separate 13.6 kg batches of a commercial summer sausage formulation were inoculated to contain an initial level of 106 cells/g of Listeria monocytogenes Scott A. In each of two independent studies, an ca. 2 log10 CFU/g reduction of L. monocytogenes occurred over the fermentation period, as compared to a less than 1 log10 CFU/g reduction in sausage fermented with a non-inhibitory Pediococcus strain. Inactivation of L. monocytogenes was also observed in one study where adequate acid production did not occur (pH>5.5), indicating that bacteriocin production occurred independently of carbohydrate fermentation. Following heating to an internal temperature of 64.4°C and storage up to 2 weeks, 9 of 90 sausages sampled were positive for Listeria. Recovery was intermittent and did not indicate that the bacteriocin was effective in eliminating L. monocytogenes that had survived the heating process.