Antimicrobial effect of natural preservatives in a cooked and acidified chicken meat model

The inhibitory effect of Microgard™ 100, Microgard™ 300, nisin, Alta™ 2002, Perlac™ 1902, sodium lactate and essential oil of mustard on microorganisms experimentally inoculated was screened in an acidified chicken meat model (pH=5.0) and stored for 2 weeks at a none restrictive growth temperature of 22 °C. All antimicrobials tested were used at the highest concentration recommended by their manufacturer. Sausage batter made with mechanically deboned chicken was inoculated with a mixed culture of Escherichia coli ATCC 25922, Brochothrix thermosphacta CRDAV452, and a protective culture Lactobacillus alimentarius BJ33 (FloraCarn L-2). A final cell concentration of 3–4 log CFU g−1 was targeted after cooking at a core temperature of 55 °C for each microorganism in order to assess cell count variation effectively. Composition, water activity (aw), pH and redox potential of the sausage model was also evaluated. The E. coli population decreased steadily during storage and was close or below detection level (<1 log CFU g−1) for all treatments, including the control, after 14 days. Sodium lactate was most effective against B. thermosphacta; population was 4 log lower than the control after 14 days of storage. When essential oil of mustard was used, aerobic mesophilic bacteria and lactic acid bacteria were significantly lower than the control after 2 days of storage (P≤0.05). The other antimicrobial agents tested had no significant effect on the aerobic mesophilic bacteria, E. coli, B. thermosphacta and lactic acid bacteria counts, when compared to the control.