ReviewWastes and by-products: Upcoming sources of carotenoids for biotechnological purposes and health-related applications

•Wastes and by-products from industrial residues are rich sources of carotenoids.•Vegetable and animal sources contain mostly carotenes and xanthophylls, respectively.•Extraction with organic solvents is the most frequent approach.•Combined extraction methodologies provide higher yields.•Bioresidues may become valuable sources of bioactive ingredients for different sectors.

BackgroundBioresidues valorization has gained a pivotal relevance in the last years, directly moved by consumers' demands for heathier and safer products (food, cosmetics, supplements, drugs, and so on) and by industrial companies that need to adapt their manufacturing procedures to increasingly strict regulatory guidelines. Most of the natural ingredients are considered more sought and safer than synthetic ones, but also more expensive and less abundant. Therefore, the recovery of valuable active ingredients from wastes and by-products may be an interesting and upcoming strategy.Scope and approachThe present report aims to provide an extensive approach to bioresidues valorization, focusing its chemical composition in terms of carotenoids content and their upcoming uses for biotechnological purposes.Key findings and conclusionsDaily produced and discharged industrial bioresidues derived from vegetable (peel, seeds, pericarp) and animal (wastewater, crustacean's cephalothorax and carapace, scales, tails) sources comprise the richest sources of carotenoids (carotenes and xanthophylls). Different techniques are commonly used for carotenoids recovery being the extraction with organic solvents the most frequently used. Supercritical fluid extraction, microwave- and enzyme-assisted extractions are applied, but mainly in combination. This area opens fascinating opportunities to discover and to design novel strategies for carotenoids production/accumulation, foodstuffs valorization and provide valuable ingredients to different industrial sectors.