NaCl-free processing, acidification, smoking and high pressure: Effects on growth of Listeria monocytogenes and Salmonella enterica in QDS processed® dry-cured ham

To evaluate the food safety effect of NaCl-free processing, acidification, smoking and high pressure in QDS processed® dry-cured ham, 3 ham types (non-acidified smoked, acidified, and acidified smoked) were produced according to a standard (-S) and a new NaCl-free (-F) process. Slices were spiked with Listeria monocytogenes and Salmonella enterica (three strains each, <2 log CFU/g), dried by the QDS process®, vacuum packed, high pressure treated at 600 MPa and stored under refrigeration for 112 days. Results of the challenge test showed that L. monocytogenes could only be eliminated from acidified smoked (AS) -S and -F processed ham slices at the end of storage, while S. enterica was present in all non-pressurized slices. The safest hams were those pressurized, especially AS-S hams, where L. monocytogenes was eliminated from 25 g of product immediately after HP treatment and S. enterica after 14 days. Compared with standard processing, NaCl-free processing showed lower levels of pathogens in non-pressurized slices but their elimination was delayed in pressurized ham slices.