The interaction of the non-bacteriocinogenic Lactobacillus sakei 10A and lactocin S producing Lactobacillus sakei 148 towards Listeria monocytogenes on a model cooked ham

摘要

Two lactic acid bacteria, Lactobacillus sakei subsp. carnosus (10A) and lactocin S producing Lactobacillus sakei 148 (LS5), were examined for their usefulness as protective culture in the biopreservation of cooked meat products. Co-culture experiments on a model cooked ham (MCH) between 10A or LS5 and a cocktail of three Listeria monocytogenes strains were performed to examine the influence of inoculum level (10~5 vs. 10~6cfu/g), storage temperature (4 vs. 7℃) and packaging type (vacuum-packaging vs. modified atmosphere-packaging). At 7℃, applying Lactobacillus sakei 10A at 10~6 cfu/g limited the growth of Listeria monocytogenes to < 1 log_(10) cfu/g during 27 days, whilst an application level of 10~5 cfu/g failed to prevent growth to unacceptable levels. Lactobacillus sakei LS5 did not demonstrate an antagonistic effect towards Listeria monocytogenes. Lowering the temperature to 4℃ or switching from vacuum-packaging to modified atmosphere packaging (MAP) did not influence the ability of strain 10A to grow on the MCH, as its dominance did not change. A combination of strain 10A and 4℃ or a MAP containing 50% CO_2 completely inhibited the growth of Listeria monocytogenes. Sensory assessments and pH measurements confirmed that 10A, even when present at a high level for prolonged storage times, did not acidify the cooked ham to a point of sensory rejection.