Collagen is the major structural protein of the connective tissues as skins, tendons, ligaments, and bones, being the most prevalent component of the extracellular matrix (ECM). It represents about one-fourth of the total protein content on most animals. Up to now, bovine and porcine origin by-products are the common sources for the production of collagen in industrial context, but religious constraints and risks associated to diseases, like bovine spongiform encephalopathy (BSE), have demonstrated to be a serious disadvantage. Lately, numerous alternatives are being exploited, as by-products from marine origin (particularly fish skins), without the concerning that the mammals materials present. Fishery industries generates tons of fish waste (about 75% of fish weight is discarded as skins, bones, fins). These remains can be seen as by-products with high value through extraction of biopolymers such as collagen, with biomedical relevance or even used in cosmetic field as component of skin care formulations, besides other uses in nutraceutics and food supplements. Collagen is well known for its contributions as anti-aging and anti-wrinkling product, which requires invasive procedures (injectable products) or breaking down to low molecular peptides capable to pass the skin barrier. Additionally, collagen can be also used in the development of cosmetic formulations as a moisturizer and natural humectant component with a high substantivity to the skin. Thereby, the public search for innovative, sustainable, and efficacious products to produce new cosmetic formulations has brought marine collagen a new valuable trend component in cosmetic industry.

Collagen has been extracted from Atlantic cod (Gadus morhua) and Atlantic salmon (Salmo salar) skins and further characterized to assess its purity, amino acid profile, denaturation temperature, structural characteristics, humidity uptake capacity, as well as a biological assessment of the extracts regarding the irritant potential to the skin. The results showed the successful isolation of type I collagen with high purity, however with some structural and chemical differences between sources. Codfish collagen demonstrated to have a good capacity to retain water being thus suitable for cosmetic applications as moisturizer. By assessing the topical exposure of collagen using a human reconstructed dermis, as well as the analysis of molecular markers for irritation and inflammation, it was observed that the produced collagen exhibited no irritant potential. With this work we demonstrate that marine-origin collagen has potential for inclusion in dermo-cosmetic applications and might constitute a sustainable and low-cost platform for biotechnological valorization of fish by-products.