Inactivation of Escherichia coli O157:H7 in dry-cured ham by high-pressure treatments combined with biopreservatives

The effect of high-pressure (HP) treatments combined with biopreservatives such as a commercial nisin or pediocin on the survival of Escherichia coli O157:H7 and the physicochemical, rheological and color characteristics of sliced dry-cured ham stored under mild temperature abuse conditions (8 °C) was investigated. Immediately after treatments, a synergistic antimicrobial effect was registered when 400 MPa and 500 MPa for 10 min combined with nisin were applied. After 60 d, this synergistic effect was only maintained with the combined treatment of 500 MPa and nisin. Counts of E. coli in dry-cured ham were not affected by either nisin or pediocin applied individually, whereas counts in pressurized samples were 3 log units lower than in non-treated dry-cured ham after 60 d of refrigerated storage. Changes in textural parameters caused by pressurization and biopreservatives were minor. Lightness (L*) values were slightly affected, with lower values in samples pressurized at 500 MPa in combination with bacteriocins and a trend to decrease during storage. Redness (a*) and yellowness (b*) were less modified by HP and biopreservatives and tended to diminish during refrigeration. The results obtained in the present work demonstrate the effectiveness of pressurization of sliced dry-cured ham at 500 MPa for 10 min combined with nisin on the inactivation of E. coli O157:H7.