High-Pressure Cold Pasteurization of Gilthead Seabream Fillets: Selection of Process Conditions and Validation of Shelf Life Extension

The objective of this study was to identify and kinetically study the most high-pressure (HP) resistant deteriorative factor of gilthead seabream (Sparus aurata) fillets aiming in their shelf life extension using in pack cold pasteurization technology. Fillets were HP processed (600 MPa, 25 °C, 5 min) and stored at 15 °C for 15 days, until spoilage. Lactobacilli were isolated from the spoiled fillets and were identified and classified as Pediococcus spp. The necessary HP process conditions for Pediococcus spp. cells inactivation were studied at various combinations of pressure (150–600 MPa) and temperature (20–40 °C) for appropriate time. The D values were calculated at all pressure–temperature combinations. The effect of temperature (zT) and pressure (zP) was estimated at all pressures and temperatures, respectively. According to the developed model for Pediococcus spp. inactivation, HP treatment of seabream fillets at 600 MPa and 25 °C for 5 min seemed to be capable for a 6-log10 reduction of the initial microbial load, potentially providing shelf life extension. Shelf-life experiments were conducted for validation. Untreated and HP treated at 600 MPa for 5-min samples were stored at 0, 5, 10 and 15 °C. Quality indices (colour, texture, microbial growth, sensory scoring) were monitored and kinetically modelled. Temperature dependence of quality loss rates was modelled by the Arrhenius equation. Microbial growth was well correlated with the sensory indices. HP treatment led to significant shelf life extension of fillets. Based on sensory scoring, the shelf life of the untreated samples was 11, 7, 4 and 3 days while for the HP-treated fillets 37, 27, 17 and 10 days after storage at 0, 5, 10 and 15 °C, respectively.