Fish skin gelatin based packaging films functionalized by subcritical water extract from spent coffee ground

The ever-increasing concern about environmental damage caused by plastic waste and its resulting threats on aquatic life has created a greater interest to replace plastics with sustainable and biodegradable alternatives. In this study, packaging film were developed from two abundant wastes, fish skin and spent coffee ground (SCG). The films were produced using gelatin extracted from fish skin impregnated with SCG extracts (SCGE) obtained via subcritical water treatment at different concentrations (0–20 %, w/w). The produced films were characterized for optical, mechanical, thermal, structural, and physical properties. Antioxidant and antimicrobial activities of the films were also evaluated. Solubility in water, moisture content, transmittance, and water vapor permeability of the films decreased as the level of SCGE impregnation increased, whereas surface hydrophobicity and transparency of the film increased with increasing the level of SCGE incorporations. The release of impregnated phenolic compounds from the films into the food simulant was 56.9, 39.8, 34.4, and 30.9 % for films with 5, 10, 15, 20 % SCGE respectively. The films showed high antioxidant activity and antimicrobial activity for common food poisoning bacteria such as Bacillus cereus, Staphylococcus aureus, Listeria monoscytogen and Escherichia coli. Therefore, results demonstrated the potential of converting wastes into promising active packaging films that can be used in food and other related sectors.