Modelling the impact of water activity and fat content of dry-cured ham on the reduction of Salmonella enterica by high pressure processing

This work aimed to quantify the impact of aw and fat content of dry-cured ham on the Log reduction of Salmonella enterica by high pressure (HP). Dry-cured ham with adjusted aw (0.86-0.96) and fat content (10-50%) was inoculated with S. enterica and pressurised (347-852 MPa, 5 min/15 °C), following a Central Composite Design. Polynomial regression indicated a significant impact of pressure and aw on S. enterica HP-lethality. By lowering aw a clear piezoprotection was observed. At low aw (0.88) the S. enterica reduction was little affected by increasing pressure (e.g. 2.3 to 3.2 Logs at 450 to 750 MPa, respectively). At the highest aw the estimated inactivation ranged from 3.3 to 8.9 Logs at 450 to 750 MPa, respectively. No significant piezoprotective effect on S. enterica was recorded by the fat content. The relevance of food characteristics on the HP-lethality of S. enterica indicate the need to validate the HP effectiveness on the specific product.