Scaling the blue gold: process challenges and scale-up constraints in fish skin-derived collagen bioproducts.

Collagen is a widely studied biomacromolecule valued for its biocompatibility, low cytotoxicity, and high water-binding capacity, enabling its use across food, cosmetic, nutraceutical, and biomedical sectors. Fish processing by-products, such as skin and scales, offer a rich and sustainable source of collagen type I, providing an eco-friendly alternative to land-based sources. Marine derived collagen is favored for its lower zoonotic risks, minimal ethical and religious barriers, and high acceptability in biomedical applications. Despite numerous successful laboratory studies and the abundant availability of fish processing by-products, current marine collagen extraction methods remain impractical at commercial scale. This review explores the transition from lab to industrial scale extraction, highlighting critical drawbacks such as excessive water and salt requirements and the need for continuous low temperature operations. We also examine often neglected issues, particularly unquantified collagen losses during processing. Emerging strategies such as whole biomass valorization that utilizes both skins and scales, alongside innovative techniques are assessed as scalable and eco-efficient alternatives. Collectively, these insights outline a roadmap for developing cost-effective, sustainable, and industrially feasible systems for extracting collagen from fishery by-products.