Modification and improvement of biodegradable packaging films by cold plasma; a critical review

Cold plasma is one of the techniques used in recent years to improve the functionality and interfacial attributes of biopolymers. Employing cold plasma for the treatment and modification of biopolymers possesses several advantages including its biocompatibility, elimination of toxic solvents usage, treatment consistency, and appropriateness for heat-sensitive ingredients. Most studies have presented the efficacious use of cold plasma treatment in improving structural, mechanical and thermal properties of film composites. In addition, cold plasma improves the film surface characteristics, particularly in protein-based films, through bringing up the polar functional groups onto the bio-composite surface, consequently increasing roughness, improving printability, increasing adhesion, and reducing contact angle; while it is not effective in the improvement of water vapor permeability of edible films. Cold plasma-treated edible packaging films experienced significant improvement where exposed to microbial contaminations, mainly due to the non-thermal nature of cold plasma technology leading to the protection of antimicrobial potency of bioactive compounds and antimicrobial constitutes. Therefore, it can be concluded that cold plasma treatment is an innovative strategy to strengthen the edible film characteristics as a promising alternative to the currently used chemical and physical modification approaches.