This booklet discusses the role of astaxanthin as a nutrient and its role in fish flesh and skin coloration.
The full benefits of the biological functions of astaxanthin are only just being discovered. It is clear that salmonids have evolved systems of deposition and storage of astaxanthin in their flesh so that it can be mobilised and utilised during maturation and at times of stress. As a natural biological antioxidant it is more efficient than either vitamin E or ß-carotene.
The secondary role in the aquatic environment is as a natural flesh and skin colorant. The distinctive pink-red flesh colour of salmon and trout provided by astaxanthin plays an important role in the attractiveness of the finished food product. The colour, derived from astaxanthin, is part of the culinary appeal of salmonids, shrimps and red sea bream. Astaxanthin is responsible for this coloration and, because fish and shrimps cannot synthesise astaxanthin themselves, they have to rely on a dietary intake. Under intensive culture conditions, astaxanthin is included in the complete feed for salmonids in order to produce the desired flesh colour. This is essential if the farmed fish product is to mimic its ‘wild’ counterpart and have maximum consumer appeal. One of the key determinants for a consumer making a buying choice is the visual appearance of the product.
Throughout the growth cycle of the fish the pigmentation of the flesh is influenced by a number of exogenous and endogenous factors. Collectively these factors lead to a high variation in flesh pigmentation in any one population of fish. Given this inherent variability it is a challenge to the academic and the aquaculturist to produce populations of fish with the desired flesh colour using the appropriate pigment management.
