Thermoplastic cassava starch-chitosan bilayer films containing essential oils

Starch-chitosan bilayer films, containing or not essential oils in the casted chitosan layer were obtained by thermo-compression. Bilayer films exhibited a good interfacial adhesion and better mechanical resistance than starch monolayers, although they were less stretchable and less transparent. Starch-chitosan films were effective at controlling the bacterial growth in pork meat, but the thermal treatment applied to obtain the bilayers reduced their antimicrobial properties as compared to chitosan monolayers. The addition of essential oils did not promote any antimicrobial action in chitosan mono and bilayer films applied to pork meat. The final amount of essential oils in the films was very limited probably due to the losses occurred during film processing method. Other strategies to incorporate the essential oils into chitosan-based films should be used to improve their final retention in the film matrix and their effective release into the coated food.