Development of multifunctional chitosan packaging film by plasticizing novel essential oil-based hydrophobic deep eutectic solvent: Structure, properties, and application.

To improve the limited mechanical and water barrier properties of chitosan film while granting extra functionalities simultaneously, present study pioneered the incorporation of chitosan film with newly developed essential oil (EO)-based hydrophobic deep eutectic solvents (HDES, EO:octanoic acid (OA), EO:menthol (ME) and OA:ME:EO). The highest tensile strength (66.22 MPa) and elongation at break (45.99 %) were obtained in OA:ME:EO-40 and OA:ME:EO-80 films, respectively. The OA:EO-based films showed excellent and stable hydrophobicity. HDESs also endowed film with additional functionalities including thermal stability, bio-compatibility, controlled release, antioxidant, and antibacterial capacity. The extension of the storage period of strawberry treated with OA:EO-containing films confirmed their preservation ability. Compared with ME:EO and OA:ME:EO, OA:EO had better compatibility with chitosan matrix and could serve as a promising plasticizer for strengthening functionalities of chitosan film. These results also promote application of HDESs as emerging plasticizers in manufacture of other polymer-based packaging film.