Purpose: To investigate the antimicrobial effect of HPP, in combination with natural marinades, against Listeria monocytogenes in a ready-to-eat, cooked pork meat product, during chilled storage.
Methods: Lemon juice (1:1v/v), pomegranate juice (1:1), white wine (1:1) and oreganum oil (0.1 or 0.2%), were screened against L. monocytogenes (4-5 log CFU/ml; 5-strain composite), in a sterile meat homogenate (10% w/v), within 30 min at 4°C. The two most effective ingredients were selected and further evaluated for their antimicrobial activity in combination with 400 or 600 MPa/2min of HPP, in a cooked (70°C, 10 min) pork meat product inoculated with 3-4 log CFU/g L. monocytogenes. Marinade- and HPP-treated samples were stored aerobically at 4 or 10°C and were analyzed for pathogen populations and Total Viable Counts (TVC), at appropriate time intervals.
Results: Results showed a 0.5 (pomegranate juice, white wine) to 1.6 (lemon juice) log CFU/ml reduction of L. monocytogenes counts. Marinades combined with 600 Mpa/2min of pressure reduced (P<0.5) the pathogen below the detection limit (<0.3 log CFU/g) until the end of storage (40 days). Similar trends were obtained for TVC. Effective antimicrobial treatments and combinations, from the most to the least effective were: Lemon juice (L)+600 MPa, pomegranade juice (P)+600 MPa, L+400 MPa, P+400 MPa, 600 MPa, 400 MPa, P, L.
Significance: These data showed that marination combined with HPP may be used by the meat industry as alternative preservation technologies.