Microbial competitiveness and risk of ochratoxin A in salami: in situ evaluation along maturation.

Abstract

This study investigated interactions and competition between the starter culture Penicillium nalgiovense and the toxigenic fungus Aspergillus westerdijkiae, focusing on their effects on processing parameters and on ochratoxin A (OTA) production on the dry-fermented salami surface during ripening. The influence of Lactococcus lactis, incorporated into the meat matrix, was also assessed. Salami was produced in accordance with official technical standards in a controlled environment. Half of the meat batter was inoculated with L. lactis. Following stuffing, salami was treated with one of three inoculum solutions: (A) P. nalgiovense, (B) P. nalgiovense plus A. westerdijkiae, or (C) A. westerdijkiae alone. Samples ripened for 20 days under industry-standard conditions. At days 0, 4, 8, 12, 16, and 20, pH, water activity, total bacterial counts in the meat, total fungal counts on the casing, and OTA concentrations in both matrices were measured. A. westerdijkiae rapidly colonised and dominated the casing surface by day 4, even in the presence of P. nalgiovense, and reached peak growth between days 8 and 12. OTA concentrations increased significantly after day 12, reaching 69 μg/g in the casing and 16 μg/g in the meat by day 20. Indicating that the surface provides more favorable conditions for toxin production, so removing casing could reduce the exposure to the toxin. The addition of L. lactis accelerated early acidification and temporarily reduced bacterial load but did not significantly affect fungal growth or OTA biosynthesis. These findings demonstrate that, under favorable environmental conditions, toxigenic fungi represent a significant food safety risk during salami ripening. Starter cultures alone are insufficient to prevent mycotoxin contamination in dry-cured meat products.