| Polyvinylidene chloride (PVDC) copolymer films containing nisin, potassium sorbate, lactoferrin, sodium diacetate or sorbic acid were developed to have antimicrobial activity against four strains of Listeria monocytogenes (CWD 95, CWD 246, CWD 201 and CWD 1503). Only films containing nisin, potassium sorbate and sorbic acid had antimicrobial activity. The minimum concentrations of nisin, sorbic acid and potassium sorbate that had antimicrobial activity using a disc diffusion assay were 1.0%, 1.5% and 2.0% (w/v), respectively. Films containing sorbic acid had the most antimicrobial activity, best barrier and mechanical properties, and greatest distribution of sorbic acid in the polymer structure. The polyvinylidene chloride copolymer coating containing 3.0% (w/v) sorbic acid in a 0.75 mil coating thickness on polyethylene terephthalate (PET) film had antimicrobial activity against L. monocytogenes.; PVDC films containing 1.5% and 3.0% (w/v) sorbic acid were selected to verify their antimicrobial activity on Cheddar cheese and bologna, which were previously surface inoculated with L. monocytogenes (CWD 95) at inoculum levels of 105 or 103 CFU/g. Both products were examined at selected intervals for numbers of L. monocytogenes, mesophilic aerobic bacteria, lactic acid bacteria, and yeast/mold. Films containing 1.5 and 3.0% (w/v) sorbic acid decreased L. monocytogenes populations 0.1–1 log and 4.0–7.0 logs on cheese and bologna after 35 and 28 days refrigerated storage, respectively. Potential reduction in the number of mesophilic and lactic acid bacteria was also found on both cheese and bologna using film containing sorbic acid. Mold growth was found only on cheese wrapped with sorbic acid-free film.; The migration of sorbic acid from PVDC antimicrobial films into Cheddar cheese and beef bologna was determined using high performance liquid chromatography (HPLC). At the end of refrigerated storage, 40 and 93% of the sorbic acid migrated from the film into Cheddar cheese and bologna, respectively. The rate constant for Cheddar cheese was 0.007 per day, and for bologna was 0.040 per day. |
