Survival of Naturally Contaminating Listeria monocytogenes in Commercial Mediterranean-Style Dry Fermented Sausages during Storage

Abstract

The aim of the present study was the determination of Listeria monocytogenes, competitive microbiota, microbial hygiene indicators, and physicochemical parameters in the typical Mediterranean-style fermented sausages Salsiccia Sarda. A batch of Salsiccia Sarda (25 samples) naturally contaminated by L. monocytogenes and vacuum packaged after 24 days of ripening was included in the study. Fifteen samples stored at 88C were analyzed after 13 days, after 90 days, and at the end of shelf life (after 180 days from vacuum packaging). Ten vacuum-packaged samples were stored at 128C in a domestic fridge simulating temperature abuse and were evaluated at the end of the shelf life. Samples were subjected to physicochemical analysis (pH and water activity) and investigated for the presence and enumeration of L. monocytogenes. Competitive microbiota, lactic acid bacteria, coagulase-negative staphylococci, and microbial hygiene indicators (total mesophilic bacterial counts, Enterobacteriaceae, Enterococcuss spp., and Staphylococcus aureus) were determined in all the samples. Although a decreasing trend in L. monocytogenes prevalence was observed through the shelf life, the detection of this pathogen in fermented sausages confirms its ability to overcome hurdles of the manufacturing process. The results highlight the importance of the careful evaluation of the Salsiccia Sarda production process by food business operators to maintain unfavorable conditions for the growth of L. monocytogenes.