High hydrostatic pressure treatment of raw sausages: impact on microbiological safety, textural properties and colour

This study aimed to assess High Hydrostatic Pressure (HHP) process (5 min at 600 MPa) effects on the quality and safety of commercially produced raw pork sausages. In particular, the evolution of key microbial populations was monitored under different storage conditions, including thermal abuses before HHP treatment or during storage. The results showed an increase in shelf-life up to 90 days in HHP-treated samples, compared to 15-20 days for conventional products. Overnight storage at 15 °C before HHP affected the quality only of untreated samples, while storage at 8 °C after HHP strongly increased microbial counts. In addition, challenge tests were performed using Salmonella Enteritidis, Staphylococcus aureus and Listeria innocua . HHP treatment was effective against S. Enteritidis, while L. innocua remained below the detection limit during the storage, but was qualitatively detected after 90 days. Staph. aureus was the most resistant, showing a 3-log reduction after HHP, with stable counts during storage. The study also evaluated the effects of HHP on texture and colour during storage at 4 °C, evidencing increased hardness and chewiness in treated samples, with reduced exudate release. Colour parameters were initially affected by the treatment but showed convergence with control samples over the storage period.