Improvement of fish protein films properties for food packaging through glow discharge plasma application

Myofibrillar proteins have good film forming ability, that leads to the formation of polymers with interesting properties for food packaging development. However, as other bio-sourced macromolecules, they have limited performance compared to synthetic materials and cold plasma represents a promising strategy to change polymer properties. Alternating current (AC) glow discharge plasma is a novel and innovative approach for surface modification of agro-based films in order to improve their properties. Then, the effects of exposure to AC glow discharge plasma were studied on the physicochemical, microstructural and thermal properties of myofibrillar protein films from fish. Films treated for 2 min showed increased elongation at break and decreased tensile strength, while the opposite behavior was observed after 5 min of treatment. Solubility in water increased with 5 min and water vapor permeability increased with 2 min of plasma treatment. Color and opacity also increased probably as a result of chemical changes because of plasma application. Slight changes were observed in microstructure of the films. Thermal properties results agreed with the modifications observed in physicochemical performance, which might be attributed to polymer surface functionalization and etching. Thus, the AC glow discharge is a promising alternative to other strategies in order to advance properties of myofibrillar protein films for food packaging because it is a dry process, does not cause damage by heating in the material, and does not pollute the environment.