Edible Gelatin Films from Cold Water Fish Skin and Sodium Alginate

Synthetic food packaging remains a looming environmental hazard. Biodegradable alternatives from renewable natural raw materials may be a solution to this problem. Edible packaging films can be produced from fish waste gelatin and seaweed sodium alginate. They combine environmental benefits with the functional characteristics required by the food industry. This article introduces a new environmentally friendly packaging film and its physicochemical profiles depending on the ratio of cold-water fish waste and sodium alginate. The experiment also included selecting the optimal type and concentration of plasticizer for safe and long food storage. The experimental films consisted of different mixes of cold-water fish skin gelatin, brown algae sodium alginate, and glycerol or sorbitol. The films were tested for thickness, moisture content, vapor permeability, moisture absorption, tensile strength, flexibility, and thermal properties. Optical microscopy, IR spectroscopy, and differential scanning calorimetry made it possible to analyze the structure, physicochemical properties, and thermal stability. The statistical processing relied on the Student’s t-test method. An optimal ratio of components yielded films with improved mechanical and barrier properties, low hygroscopicity, low vapor permeability, and high melting temperatures (135–138 °C). The samples with sorbitol as plasticizer demonstrated a more uniform structure, resulting in low vapor permeability (829–1,122 g/m2), reduced moisture absorption (≤ 98%), and high tensile strength. The samples with glycerol had better plasticizing properties, but higher vapor permeability (1,572–1,895 g/m2) and moisture absorption (114–179%). The established patterns may help to control the properties of industrial biopolymer compositions by adjusting the type of plasticizer and the concentration and ratio of components to obtain novel food films with improved mechanical characteristics and low hygroscopicity.