Investigation on the microbiological hazards in an artisanal salami produced in Northern Italy and its production environment in different seasonal periods

In the present study, the occurrence of Listeria monocytogenes, Staphylococcus aureus, Salmonella spp. and Escherichia coli VTEC was investigated in two batches of artisanal Italian salami tested in winter and summer. Moreover, enumerations of total bacterial count, lactic acid bacteria and Enterobacteriaceae were performed as well as monitoring of water activity and pH. Samples were taken from raw materials, production process environment, semi-finished product and finished products. The results revealed an overall increase of total bacterial count and lactic acid bacteria during the ripening period, along with a decrease of Enterobacteriaceae, pH and water activity. No significant difference was observed between the two batches. The enterobacterial load appeared to decrease during the maturation period mainly due to a decrease in pH and water activity below the limits that allow the growth of these bacteria. E. coli VTEC, Salmonella spp. or L. monocytogenes were not detected in both winter and summer batches. However, Klebsiella pneumoniae was detected in both summer and winter products. Except for one isolate, no biological hazards were detected in the finished salami, proving the efficacy of the ripening period in controlling the occurrence of microbiological hazard in ripened salami. Further studies are required to assess the virulence potential of the Klebsiella pneumoniae isolates.