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

Ohio, Columbus

Workshop; International Nonthermal Food Processing Workshop; 2014

Post-processing manipulation of meat products can result in pathogenicbacteria contamination. High Pressure Processing (HPP) has been approvedas a post-packaging treatment for pasteurization of ready-to-eat foods. Thesynergistic effect of HPP and natural antimicrobials has been proved in somefoodstuffs. The aim of this work was to evaluate the effect of HPP and thebacteriocin lactocin 705/AL705 produced by Lactobacillus curvatus CRL705against 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 preparedwith 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 individually vacuum-packed and treated at 400MPa (C400, L400) or600MPa (C600, L600) for 5min at 5°C. Unpressurized samples (C0, L0) werealso prepared. L. innocua 7, total aerobic mesophilic bacteria (TAMB) and lacticacid bacteria (LAB) were analyzed after 1, 20 and 40 days of storage at 4±1°C.The pH values and aw were also measured. Results showed that treatments L0and C400 reduced about 1 log unit the growth of L. innocua 7 compared withthe control (C0) during the first 20 days at 4±1ºC. However, no differences wereobserved after 40 days of storage, which indicates the re-growth of themicroorganism. A similar tendency was observed when treatments L400 andC600 were applied; although, in these cases the reduction of L. innocua 7 wassignificantly (p<0.05) higher. Only treatment L600 was effective to keep L.innocua 7 below the detection limit throughout 40 days of storage. TAMB andLAB counts were significantly (p<0.05) reduced by HPP treatments but not bylactocin 705/AL705. No significant differences (p>0.05) among treatments wereobserved in pH (6.36±0.08) and aw (0.985±0.001) values.