Evaluating Traditional and Alternative Eco-Friendly Collagen Extraction Methods From Narrownose Smooth-Hound Skin: A Sustainable Waste Reduction in the Fishing Industry.

Reducing waste in the fishing industry and adding value by implementing a circular economy is a key objective to establish a more sustainable use of the natural resources. This waste contains various bioactive molecules, such as collagen, which presents an increasing demand from the consumers. The narrownose smooth-hound (Mustelus schmitti) processing generates a large amount of residues. This study aimed to optimize the traditional collagen extraction process and evaluate alternative eco-friendly collagen extraction techniques using the narrownose smooth-hound skin as raw material. Results showed that the pre-treatment optimal conditions were 2 h of deproteinization followed by 6 h of defatting. Acid extraction required 72 h to achieve maximum yield. Likewise, the maximum yield for the enzymatic extraction was obtained using 10% v/v pepsin and 24 h of treatment. As an alternative technique, an enzymatic extraction was conducted using an endogenous enzyme obtained from the narrownose smooth-hound stomach. This method acquired higher yields than the acid control and slightly lower yields than the commercial pepsin control. On the other hand, an acid extraction assisted with sonication was evaluated, with no significant differences observed. All extracts obtained were characterized by SDS-PAGE, FTIR, UV-spectra, and amino acid profile, confirming the presence of type I collagen. This study offers a sustainable solution to reduce fishery waste, generating two value-added products, collagen and endogenous enzymes. PRACTICAL APPLICATIONS: Optimization of collagen extraction from fisheries waste. Enzymatic extraction showed higher yields than the acidic one. Endogenous enzymes of fishery waste are a viable alternative for collagen extraction. The extracts obtained have characteristics that suggest type I collagen.