Bactericidal synergism through bacteriocins and high pressure in a meat model system during storage

Abstract

High hydrostatic pressure represents an attractive non-thermal process for meat products to avoid post-processing contamination. When combined with antimicrobials, like bacteriocins, the death rate may be increased because of sub-lethal injuries to living cells. The behaviour of several foodborne bacteria inoculated in a meat model system with added bacteriocins (enterocins A and B, sakacin K, pediocin AcH or nisin) after pressurization (400 MPa, 10 min, 17°C) and during chilled storage was investigated. Although Staphylococcus was the genus least sensitive to pressurization, the samples including nisin displayed lower and significantly different counts during the 4°C storage than the rest of the treatments. A greater inactivation of Escherichia coli (>6 log 10) in the presence of nisin was recorded, the number of survivors remained unchanged during storage at 4°C for 61 days. Nisin was also the bacteriocin capable of maintaining slime-producing lactic acid bacteria below the detection limit (<10 2 cfu g −1 ). Listeria monocytogenes in treatments with sakacin, enterocins or pediocin was kept <10 2 cfu g −1 till the end of storage (61 days). Salmonella enterica subsp. enterica ser London and Salmonella enterica subsp. enterica ser Schwarzengrund counts in every treatment were kept at the level obtained after pressurization, with no significant differences between treatments during the chilled storage.