Feed Additives for Influencing the Color of Fish and Crustaceans

Abstract Consumers generally seem to prefer red-colored products of salmonids as salmon, trout, and charr. When tested, consumers favored pink salmon over orange or dark, kipper-like colored salmon. For consumers, the red color appears to serve as an indicator of quality parameters, such as freshness and flavor. Thus, the necessity to modify the color of fish by adding carotenoids to the feed is based on the expectation of the consumer regarding the color of the fish flesh. Astaxanthin, being the most important carotenoid, is available from natural sources (crustaceans, algae, and yeast), from synthetic sources, and by metabolic engineering. Legal requirements for the addition of carotenoids to fish feed have been detailed and changed over the last two decades. For example, the current situation in two major marketplaces where salmonid fishes are of economic importance—the European Union and the United States—are described in this chapter. Different chromatographic methods are applied for the separation of astaxanthin and other carotenoids in fish samples, including open-column methods, thin-layer chromatography, and, in particular, high-performance liquid chromatography. Spectrophotometric and electrochemical detection, nuclear magnetic resonance, and different mass spectrometric methods can be used for their identification and quantitation.