Extraction of Fish Protein Concentrates from Discards and Combined Application with Gelatin for the Development of Biodegradable Food Packaging

Fish waste accounts for almost one-third of the total fish production annually. The main objective of this study was to upcycle fish by-products to produce biodegradable packaging materials. Fish protein concentrate (FPC) was extracted from gilthead seabream by-catch (flesh and skin). FPC (3%) and gelatin (3%) were used to produce film-forming solutions. The films were produced according to the solvent casting method. The produced films were tested as packaging materials via the determination of different film properties. The wettability of the packaging materials was characterized based on the determination of the contact angle. Water vapor permeability was evaluated using the ASTM E96/E96M standardized method. The evaluation of mechanical properties was based on the Young’s modulus, tensile strength, and elongation at break. Color was measured using a CIELab system. The incorporation of FPC into the produced membranes resulted in a reduced contact angle from 108.5° to 90.6°; however, both films were characterized as hydrophobic materials. Films supplemented with FPC had lower tensile strength values compared to pure gelatin films, but higher elongation values without statistically significant differences. The color parameters (L,a,b) indicated that gelatin films and FPC–gelatin films were colorless and transparent (L > 90), an important parameter for food packaging materials. The production of biodegradable packaging materials from FPC and gelatin may effectively reduce petroleum-based plastics under the circular economy model.