Encapsulation and controlled release of antifungal propionic acid utilizing biodegradable active films based on natural polymers

Propionic acid represents a powerful and volatile antifungal agent widely used for protection of dry agricultural products such as grain and cereals. To improve its effectiveness and safety, we incorporated propionic acid into an active film matrix. A series of biodegradable antifungal films loaded with propionic acid and based on natural polymers chitosan and gelatin were prepared. The structural and functional properties of the prepared active films were studied utilizing various spectroscopic, microscopic and analytical techniques. The release of propionic acid from the active films was examined at varying temperatures and humidity conditions. An edible oligosaccharide, beta-cyclodextrin, was added during film preparation to form hydrogen bond interactions with propionic acid. It was found that beta-cyclodextrin significantly increases loading capacity of the film matrix resulting in high amounts of encapsulated propionic acid. It was found that encapsulation into active film matrix allows for the control and therefore for the inhibition of the propionic acid release rate, thus enabling the maintenance of an effective concentration of the antimicrobial agent for prolonged periods.