73.
The effectiveness of antimicrobial mixtures against
Listeria innocua 7, used as a
L. monocytogenes surrogate, was investigated in broth and a food system. Synergistic effects were found for nisin (Nis), potassium sorbate (PS), calcium propionate (CP) and sodium lactate (SL), Nis + PS being the most effective binary mixture that exhibited listericidal activity in broth. To assess the effect of adding lactocin AL705 (AL705) to Nis + organic acid salt combinations, tridimensional isobolograms were generated. Sub-MIC combinations of the antimicrobials exerted bactericidal activity against
L. innocua 7 after AL705 addition to the binary mixtures. However, when applied on Sardo cheese contaminated with
L. innocua 7 (initial inoculum 4.45 ± 0.06 CFU g
−1), only Nis + PS + AL705 produced count reductions respect to the control, reaching 3.04 ± 0.35 CFU g
−1 counts after 15 days at 15 °C. Ternary combinations containing AL705 showed potential to reduce antimicrobial usages for
L. innocua 7 inhibition.
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