Influence of the processing method and antimicrobial agents on properties of starch-gelatin biodegradable films

Abstract

[EN] Biodegradable films based on corn starch (CS), bovine gelatin (BG), glycerol as a plasticizer, and lysozyme or N--lauroyl-l-arginine ethyl ester monohydrochloride (LAE) as antimicrobial agents were obtained by both extension-drying (casting) of the aqueous dispersions and melt blending and compression moulding. Microstructural analyses revealed the lack of miscibility between CS and BG, which implied polymer phase separation, with the formation of domains rich in each polymer, with different arrangements for casting and melt blending processes. Thermoprocessed films were more permeable to water vapour (60%-115%) and oxygen (70%-355%) compared to the corresponding cast films and exhibited lower stiffness (50%-75%) and resistance to break (17%-33%) and greater extensibility (150%-190%) than casting films. LAE improved the water vapour barrier and reduced the oxygen barrier of both kinds of films, whereas the opposite effect was observed for lysozyme. Antimicrobial activity against Listeria innocua was observed for formulations containing LAE processed by both casting and compression moulding, all of which exhibited a bactericidal effect. (c) 2016 Society of Chemical Industry