In this study, the effectiveness of an active polyvinylalcohol-based film against Alicyclobacillus acidoterrestris was assessed. The active film was fabricated by immobilizing an active compound on the surface of a polymeric matrix and then tested by putting the film in contact with a medium that had been inoculated with microbial cells. Microbiological tests showed that the film was antimicrobial against both a single strain and a culture cocktail of A. acidoterrestris, at 44 degrees C. By monitoring the viable cell concentration under three different packaging conditions, it was possible to demonstrate that the active film was equally effective against both the single strain and the culture cocktail and that it maintained this efficacy at various medium volumes. The same microbial tests were also conducted on viable spores of the investigated microorganism, inoculated both into a laboratory medium and apple juice. The results indicate that these viable spores were better inhibited than cells by the active film in both investigated media.