Astaxanthin: An overview of its sources, extraction methods, encapsulation techniques, characterization, and bioavailability

Carotenoids are a broad group of lipid-soluble pigments naturally produced by plants and photosynthetic organisms. In animal diets, they contribute to muscle pigmentation, which is a key criterion used by consumers when evaluating salmonids fillets as an indicator of quality. Astaxanthin (ASX) is the most common carotenoid used in both aquaculture and functional foods. ASX is produced naturally by specific microalgae and microbes, as well as synthesized chemically. Due to its numerous biological functions, including antioxidant and anti-inflammatory activities compared to other carotenoids, ASX has enormous potential for use in cosmetics, functional foods, and medicine. However, the utilization of ASX is hindered by its limited bioavailability and poor stability when exposed to certain environmental factors such as elevated temperatures, light, extreme pH and oxygen. This review examines ongoing efforts focused on the sources, extraction and encapsulation methods to address these drawbacks.