Inhibition of Salmonella on poultry skin using protein- and polysaccharide-based films containing a nisin formulation

The objective of this study was to examine the use of protein- and polysaccharide-based films containing bacteriocin formulations for inhibiting salmonellae on fresh broiler skin. The lethality of the films containing a nisin-based formulation was determined against Salmonella Typhimurium-contaminated broiler drumstick skin samples coated with the film. In the first study, varying concentrations of nisin (0, 100, 300, and 500 mu g/ml) plus 3% citric acid, 5.0 mM EDTA, and 0.5% Tween 80 were incorporated into 0.5% calcium alginate films at a 20% level (wt/wt) and then applied to Salmonella Typhimurium(NAr)- contaminated skin samples (log(10) 5.0) at a 1:2 weight ratio (film:skin). Salmonella Typhimurium(NAr) skin population reductions ranged from 1.98 to 3.01 log cycles after a 72-h exposure at 4 degrees C. In comparison to the 0- and 100-mu g/ml nisin concentrations, significantly greater population reductions were achieved at nisin concentrations of 300 and 500 mu g/ml. In related studies, the 500-mu g/ml nisin formulation was incorporated into 0.75 and 1.25% agar gels and applied to contaminated broiler drumstick skin samples (log(10) 7.0). Salmonella Typhimurium(NAr) skin population reductions following a 96-h exposure at 4 degrees C were 1.8(1.25% agar gel) and 4.6-log cycles (0.75% agar gel). These results demonstrated that the inclusion of nisin-based treatments into either calcium alginate or agar gels that were subsequently applied to contaminated broiler drumstick skin yielded significant Salmonella Typhimurium(NAr) population reductions ranging between 1.8 to 4.6 log cycles after 72 to 96 h of exposure at 4 degrees C. The level of kill was affected by film type and gel concentration (i.e., gel network formation), exposure time, and nisin concentration.