Biodegradable films from fishing industry waste: Technological properties and hygroscopic behavior

The objective was to evaluate the effect of glycerol on functional properties and sorption behavior of films elaborated with myofibrillar proteins of fish. Analyses of solubility, water vapor permeability (WVP), tensile strength (TS), elongation, and moisture sorption isotherms were performed. Films with lower glycerol concentrations (5, 10, and 15%) showed lower (p <= 0.05) permeability when compared to films with 30 and 40%. The increase in the glycerol concentration decreased the TS and increased the elongation of the lyophilized myofibrillary protein films (p <= 0.05). Glycerol significantly affected the solubility properties, with an increase of 95.96%. In the sorption process, the films presented curves types II and III, in which high concentrations of glycerol increased their water content. The sorption hysteresis decreased when the concentration of glycerol increased up to its disappearance in films with 40% glycerol. The GAB model was adequate to represent the sorption process of biodegradable films in the relative humidity range of 10-85% under the studied conditions. Films based on fish myofibrillar proteins in the presence of glycerol increase the water's binding capacity to mono and multilayers, and depending on the packaged food, like fresh produce, can preserve the moisture in the food, prolonging its shelf-life.