Antimicrobial gelatin films reduce Listeria monocytogenes on turkey bologna

Antimicrobial films and coatings may be useful to inhibit bacterial growth on ready-to-eat poultry meats. Nisaplin and Guardian CS1-50 were added at 6 and 5 different concentrations to cast gelatin-based films to inhibit Listeria monocytogenes inoculated in liquid media, solid media, and on bologna. Color properties and antimicrobial activity were measured during storage of films at 21 degrees C+/-2. For the shelf-life study on bologna, color change and antimicrobial effect of 0.5% Nisaplin and 1% Guardian were measured. The intensity of yellowness in films increased as both Nisaplin and Guardian concentrations increased. Film tensile strength and percentage of elongation decreased as incorporation of antimicrobials increased. All 6 Nisaplin films showed a 3-log reduction after 1 h and a 6-log reduction after 6 to 8 h compared with control, in which there was no reduction in Listeria population in 0.1% peptone water. Two Guardian films (0.5 and 1%) showed approximately a 3-log reduction in 24 h. In the solid media, all Nisaplin films (except 0.05%) and all Guardian films inhibited L. monocytogenes after 48 h of incubation. Nisaplin films and all Guardian films still showed antilisterial effects after 16 wk of storage in the solid media. Total color difference compared with control (bologna) decreased from highest to lowest in the following order: 1% Guardian>control (film with no antimicrobial)>0.5% Nisaplin film>bologna. Both 0.5% Nisaplin film (4 log lower than control) and 1% Guardian film (3 log lower than control) effectively inhibited L. monocytogenes on bologna during storage at 4 degrees C for 56 d.