A review article titled 'Recent applications of biopolymers derived from fish industrial waste in food packaging' was published in Polymers by Francesca Rionetto from the Department of Innovative Engineering, University of Salento, summarizing the Recent advances in the valorization of fish industry waste and the potential to reuse these by-products in a circular economy approach for the preparation of bioplastics for food packaging.
Marine Collagen
Collagen is the most common animal protein because it is present in all connective tissues (i.e. skin, bones, ligaments, tendons and cartilage) and the interstitial tissues of parenchymal organs.
Marine collagen is mainly extracted from fish skin, bones, fins, scales or connective tissue of jellyfish, sea urchin, starfish or sea cucumber. Fish skin has been used to extract collagen since 70-80% of its dry matter is collagen. In addition, fish scales are another promising and low-cost source of marine collagen, accounting for about 4% of the total annual production weight of fish offal, or about 18-30 million tons. Fish scales contain both organic components (collagen, fat, lecithin, hard protein, various vitamins, etc.) and inorganic components (hydroxyapatite, calcium phosphate, etc.).
Compared to mammalian collagens, marine collagens have comparable or slightly lower molecular weights and lower denaturation (melting) temperatures, which are around 20-35°C for most fish, and are derived from warm-water species higher collagen values. In order to improve thermal stability, suitable cross-linking treatments have been investigated.
Compared with mammalian collagen, marine collagen has no limitations in use due to religious reasons and possible infectious diseases, and has excellent film-forming ability, biocompatibility, low antigenicity, high biodegradability and cellularity growth potential. This waste has the potential to be developed as an eco-friendly and low-cost source of collagen, with many potential applications as a drug/delivery vehicle or wound dressing in various fields such as nutraceuticals, cosmetics, and biomedicine. Collagen is a good candidate for texturing, thickening and gel formation due to its high water absorption capacity. Furthermore, it possesses interesting properties related to surface behavior, including emulsion, foam formation, stabilization, adhesion and cohesion, protective colloid function, and film-forming ability. Although it has been used as a food additive to improve the rheological properties of foods, marine collagen has not been fully exploited and its applications are much lower than that of mammalian collagen.
The use of fish collagen films in the packaging industry is limited by some disadvantages, such as low thermal stability and relatively poor mechanical properties. Furthermore, collagen is a hydrophilic polymer with hydroxyl groups. Therefore, water vapor permeates the membrane easily. Various efforts have been made to overcome these limitations, including mixing collagen with other biopolymers and several chemical and enzymatic treatments.
