Active films from water-soluble chitosan/cellulose composites incorporating releasable caffeic acid for inhibition of lipid oxidation in fish oil emulsions

In this study, antimicrobial and antioxidant active packaging films were prepared from water-soluble chitosan (N,O-carboxymethyl chitosan, NOCC) and cellulose (methylcellulose, MC). Composite films were prepared by directly blending NOCC and MC in water, followed by cross-linking the NOCC/MC composite films with calcium ions. The microstructure, water vapor permeability and mechanical strength of the composite films could be modulated via adjusting the NOCC/MC blending ratio and subsequently cross-linking the films with calcium ions. To prepare active packaging films, a natural phenolic antioxidant, caffeic acid, was incorporated into the composite films in fixed and releasable types. The caffeic acid-incorporated films showed 20-fold increases in antioxidant activity and 6-fold increases in antibacterial activity as compared to the caffeic acid-free composite films. The releasable caffeic acid could be continuously released from the composite films and showed significant inhibitory effect on lipid oxidation of menhaden oil-in-water emulsion. The caffeic acid-based active packaging may be a potential alternative approach to reduced lipid oxidation in fish oil.