Challenge Test Analysis of Salmonella Behavior During Sardinian Fermented Sausage Production and Storage

This study evaluated Salmonella behavior during Sardinian fermented sausage (SFS) production through a challenge test on experimentally inoculated raw meat. The objectives were to (i) determine the survival and reduction kinetics of Salmonella during fermentation and ripening and (ii) evaluate the relationship between pathogen behavior and the evolution of key chemical-physical parameters (pH, water activity). Three batches of SFS were produced, and the meat mixture was inoculated with a three-strain Salmonella cocktail (reference and field strains) to 10² CFU/g. After 20 days of ripening, sausages were vacuum-packed and stored under refrigerated conditions (+4 ± 2 °C). For each batch, triplicate samples were collected and analyzed at different production stages (mixing, after overnight rest, and 24 h after stuffing) and during shelf life (days 6, 21, 30, and 40). Analyses included Salmonella detection and enumeration by direct plating, aerobic colony count, Enterobacteriaceae, staphylococci, lactic acid bacteria, molds and yeasts, as well as pH, water activity, and gross composition. Salmonella counts increased by approximately one log unit after stuffing, before the onset of acidification. During fermentation and ripening, pathogen levels declined but remained detectable, even after prolonged refrigerated storage. These findings indicate that although ripening, and particularly fermentation, significantly (p < 0.05) reduce Salmonella levels, complete inactivation is not achieved. The study highlights the importance of controlling initial contamination levels, validating fermentation and ripening conditions, and the application of additional post-process hurdles to ensure product safety.