Development of a food packaging coating material with antimicrobial properties

Antimicrobial films may provide an effective way to control food-borne pathogens and spoilage microorganisms to thus enhance food safety and decrease product spoilage. Antimicrobial films can be produced by incorporation of chemical preservatives or antimicrobial agents into a plastic film. The agents can then diffuse into the food to control target microorganisms. In this work, antimicrobial coatings were developed by incorporation of nisin, lactoferrin (an antimicrobial peptide derived from bovine lactoferrin in cow's milk), sodium diacetate, sorbic acid, and potassium sorbate into a coating material. Saran(R) F-310 resin, a copolymer of vinylidene chloride, was used to produce the base coating using a solvent casting method. The antimicrobial activity of these films was verified on laboratory media against the food-borne pathogen Listeria monocytogenes. Films containing nisin, sorbic acid, and potassium sorbate inhibited L. monocytogenes strain CWD 95. The lowest level of nisin, sorbic acid, and potassium sorbate that had antimicrobial activity was 1, 1.5, and 2% w/v respectively. Films containing sorbic acid were the most compatible with the resin solution and had the best physical appearance. The water vapor barrier of films containing sorbic acid was almost unchanged compared to the control film (no antimicrobial agent). The three-dimensional structure of the films was observed using Scanning Electron Microscope (SEM). The results show that films containing sorbic acid were the most homogenous of the sample films.