Combined effect of high hydrostatic pressure and enterocin LM-2 on the refrigerated shelf life of ready-to-eat sliced vacuum-packed cooked ham

The combined effect of high hydrostatic pressure (HHP, 200 MPa for 10 min, and 400 MPa for 10 min) and enterocin LM-2 (256, 2560 AU/g) on the refrigerated shelf life of sliced cooked ham was evaluated. The evolution of microbiological, physicochemical (pH, a(w), TVB-N, lipid oxidation and color) and sensory properties, as well as enterocin activity were analyzed during a three months period of refrigerated storage. The combination of HHP and enterocin was found to inhibit the growth of bacteria of sliced cooked ham and extend the shelf life of refrigerated sliced ham. Also, a strong combined effect of both methods for inactivation of Listeria monocytogenes and Salmonella enteritidis was observed (P < 0.05). Bacteriocin activity decreased during storage and a maximum enterocin concentration of 160 AU/g was detected at the end of storage. There was no effect on physicochemical and sensory characteristics when using the treatments of 200 MPa HHP and enterocin (P >= 0.05): however, the final product possessed a comparatively short shelf life (30-40 days). HHP at 400 MPa in combination with enterocin (256 or 2560 AU/g) could extend the shelf life up to 70 or 90 days respectively and overall did not affect TVB-N values (P >= 0.05). An exception occurred on day 1 (after pressurization) when a slight lipid oxidation was induced that affected the hardness, color, odor and overall acceptability in the ham. Overall, from a microbiological and physicochemical point of view, the most effective treatment was achieved with a combination of 400 MPa HHP and 2560 AU/g enterocin, extending the shelf life to above 90 days and producing a better sensory profile during the whole storage. (C) 2011 Elsevier Ltd. All rights reserved.