SAKACIN A-CONTAINING PULLULAN FILM: AN ACTIVE PACKAGING SYSTEM TO CONTROL EPIDEMIC CLONES OF LISTERIA MONOCYTOGENES IN READY-TO-EAT FOODS

The effectiveness of sakacin A, a bacteriocin produced by Lactobacillus sakei DSMZ 6333, was evaluated against epidemic clones of Listeria monocytogenes isolated from foodborne outbreaks; sakacin A activity was determined in ready-to-eat (RTE) foods, and a biopolymer was identified to deliver the bacteriocin onto a RTE food. Sakacin A demonstrated antimicrobial activity against epidemic clones of L. monocytogenes in food slurries. When sakacin A (50 mg/mL) was applied directly to experimentally inoculated turkey breast, populations of the most sensitive epidemic clone were reduced more than 2 log(10) cfu/g after 3 weeks at 4C. Sakacin A-containing (1 mg/cm2) pullulan films demonstrated antimicrobial activity in vitro. When experimentally inoculated surfaces of turkey breast were treated with these pullulan films, L. monocytogenes populations were reduced 3 log(10) cfu/g after 3 weeks under refrigerated storage. These results demonstrate the possibility of using sakacin A-containing-pullulan film to inhibit or reduce L. monocytogenes on the surface of a RTE food. PRACTICAL APPLICATIONS Increased use of synthetic packaging films has led to ecological problems due to their nonbiodegradability. Consumers are demanding that food packaging materials be made of biobased materials, and to be easily biodegradable and recyclable. The incorporation and/or slow release of antimicrobial agents in packaging materials may provide a means of extending the bacterial lag phase, reducing microorganism growth rate and extending the shelf life of foods. Bacteriocins are compounds that can be used as a means of biopreservation. In this study, we demonstrated the effectiveness of sakacin A-containing pullulan films to control Listeria monocytogenes growth and the applicability of active pullulan films as a means of delivering a bacteriocin directly to a food surface. Pullulan films require less antimicrobial, demonstrate longer antimicrobial activity and allow for controlled migration of the molecule from film to the food matrix, as compared with the direct addition of sakacin A to ready-to-eat meat products.