Combined effect of High Pressure Processing and lactocin 705/AL705 on inactivation of Listeria innocua 7 in slices of cured cooked pork loin

DALLAGNOL, A.M.; BARRIO, Y.; VAUDAGNA, S.R. ; SZERMAN, N.; CAP, M.; MASANA, M.; CASTELLANO, P. ; VIGNOLO, G.

Ohio

Workshop; International Nonthermal Processing Workshop; 2014

The Ohio State University

Post-processing manipulation (such as cutting, skinning, slicing or packaging) of meat products can result in pathogenic bacteria contamination. High Pressure Processing (HPP) has been approved as a post-packaging treatment for pasteurization of ready-to-eat foods. The synergistic effect of HPP and natural antimicrobials has been proved in some foodstuffs. The aim of this work was to evaluate the effect of HPP and the bacteriocins lactocin 705/AL705 produced by Lactobacillus curvatus CRL705 against Listeria innocua 7 on slices of cured cooked pork loin (low NaCl level -0.6%w/w). Longissimus dorsii pork muscles were injected with brines formulated with different additives, cooked and sliced. Some slices were inoculated with L. innocua 7 (6 log CFU/cm2) and two groups of samples were prepared: (C) control without bacteriocins and (L) with lactocin 705/AL705 (105 UA/cm2). Slices were then individually vacuum-packed and treated at 400 MPa (C400, L400) or 600 MPa (C600, L600) for 5 min at 5°C. Unpressurized samples (C0, L0) were also prepared. L. innocua 7, total aerobic mesophilic bacteria (TAMB) and lactic acid bacteria (LAB) were analyzed after 1, 20 and 40 days of storage at 4±1 °C. The pH values and water activity were also measured. Results showed that treatments L0 and C400 reduced about 1 log unit the growth of L. innocua 7 compared with the control (C0) during first 20 days at 4±1ºC; after longer storage time (40 days) this difference was not observed showing the re-growth of the microorganism. A similar tendency was observed when treatments L400 and C600 were applied although in these cases the reduction of L. innocua 7 was significantly (p