Purpose: Objectives of this study are to compare two different coated antimicrobial films containing nisin for eventual application in a commercial setting. Formulations of the coatings were developed for commercial coating application versus batch lab process produced in the past. Specifically, evaluation of the film’s efficacy against Listeria monocytogenes and evaluation of the coating properties were performed.
Methods: Pectin (C1) and methyl cellulose (C2) were used as the carriers for the antimicrobial nisin in two separate coatings. Coatings contained 10,000 IU/g of nisin A. Coatings were produced same day and coated onto a PET laminate film by draw down method. Films were dried for 24 hrs before evaluation for the following; color (Δ E), coating weight, thickness (mil), percent solids (%), viscosity (Zahn cup #2 and Brookfield), pH and inhibition against L. monocytogenes using the film on lawn method. Control films did not contain nisin. Methods were completed in triplicate.
Results: Coatings achieved inhibition against L. monocytogenes compared to the control (P < 0.05). The pH of C1 averaged 2.5 and 4.38 for C2. Percent solids average was 9.5 (C2) & 4.73% (C1). Average coating thickness was 0.1 mil. Average Δ E values were less than 1.0. Average coating weight was 1.5 (C2) &1.64 lbs/ ream (C1). Zahn Cup time averaged 40-45sec. Viscosity was determined to be in the pump-able range for commercial coatings (Centipoise and torque were measured).
Significance: The coating properties collected allow for novel commercialization of coated antimicrobial films which industry currently is demanding. Both coatings were effective against L. monocytogenes and could be produced utilizing current industry equipment. To the authors’ knowledge, an antimicrobial coated film developed for commercial production has not been previously performed.