Evaluation of the Antimicrobial Effect of Bioprotective Lactic Acid Bacteria Cultures Against Listeria monocytogenes in Vacuum-Packaged Cold-Smoked Rainbow Trout (Oncorhynchus mykiss) at Different Temperatures

The growing demand for Ready-to-Eat (RTE) fish products increases the need for effective safety measures against <i>Listeria monocytogenes</i>, a pathogen associated with high fatality rates. This study evaluated the bioprotective potential of lactic acid bacteria (LAB) strains, including probiotic ones, against <i>L. monocytogenes</i> in cold-smoked rainbow trout. Two LAB cocktails were tested: a commercial mix (LC-LL) and a vegetable-derived mix (LAB2-LP15). LC-LL effectively inhibited <i>L. monocytogenes</i> at both static (5 °C) and dynamic (4-20 °C) conditions by the inhibitory effect of the bacteriocin leucocin (≈4 log unit growth inhibition). In contrast, LAB2-LP15 was effective only at 5 °C (≈2 log unit growth inhibition), maintaining the best sensory characteristics. These findings support the use of LAB as natural bioprotective agents in RTE fish, combining food safety and sensory preservation.