Starch-based films enriched with nanocellulose-stabilized Pickering emulsions containing different essential oils for possible applications in food packaging

Consumers are increasingly demanding biodegradable food packaging with a minimal amount of synthetic preservatives and, at the same time, worried about potential contaminants, particularly during any pandemic event. Plant essential oils (EO) are natural compounds with remarkable antimicrobial properties. This study aimed to prepare thermoplastic starch films (TPS) containing nanocellulose-stabilized Pickering emulsions (PE) of different essential oils: ho wood (Cinnamomum camphora), cardamom, and cinnamon, and investigate the suitability of biopolymer films as packaging material. The films were prepared via casting method and were characterized concerning chemical interactions by FT-Raman and FTIR, mechanical, crystallinity, thermal, and water vapor permeability properties. PE Ho wood-starch films showed strong chemical interactions, which significantly improved the film's mechanical resistance. The films with cardamom and cinnamon showed low compatibility, with a decrease in tensile strength. All films showed less crystallinity than the pristine TPS, which can be attributed to the starch chain organization's changes. The films showed high thermal stability due to the strong molecular interactions among starch chains and PE, as confirmed by TGA and DSC analysis. The films' thermal stability is an indication that it can be safely applied in the food industry. Besides, the films showed a lower water vapor transmission rate, and the water may act as a carrier for PE, improving the release of the active compounds. This study reveals the differences between three essential oils incorporated into starch-based films. The ho wood films are the most promising PE to be applied as biodegradable active packaging.