Inactivation of Listeria monocytogenes by pulsed light in packaged and sliced salpicão, a ready-to-eat traditional cured smoked meat sausage

Abstract

The efficacy of pulsed light (PL) for the surface decontamination of a sliced ready-to-eat cured meat product, salpicão, was studied. The surface of the slices was inoculated with Listeria monocytogenes (107 cfu/g), and then PL treatment was applied. Microbial analyses (L. monocytogenes, coagulase-negative Staphylococci (CNS), Lactic acid bacteria (LAB) and Enterobacteriaceae) were performed immediately after the treatment. pH, aw, colour and volatile profile were also evaluated. Response Surface experimental Design was applied regarding factors voltage (ranging from 1828 to 3000 V) and distance (ranging from 2.6 to 5 cm) to the light source, and a maximum of 16.11 J/cm2 energy dose was achieved. A reduction of 1.58 log cfu/g in L. monocytogenes count was obtained when a fluence of 5.31 J/cm2 was applied. Enterobacteriaceae, LAB and CNS endogenous microbial populations were not influenced by PL treatment. PL application reduced a* values and influenced b* values without impacting the sample ΔE or L* values. The potential oxidative effect of this technology was evaluated by solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS), and no significant changes were verified after its application in this sliced cured meat product.