What causes the red color in salmon

How the color gets into (farmed) salmon

Similar to a color palette with which one chooses the wall color for the new living room, the SalmoFan has 15 numbered fields on which salmon red can be seen in different color depths - from a pale 20 to a deep red 34. Depending on the desired shade, the breeder has to Add either more or less pigments to fish food. Since the dye used in salmon farming can make up up to twenty percent of the total feed price, breeders make it a point not to use more of the valuable pigment than is necessary.

The most common coloring agent used in salmon aquaculture is a carotenoid called astaxanthin. It is the same pigment that gives wild salmon its typical reddish color: it makes up more than ninety percent of the carotenoid content in fish. But even the wild relatives of farmed salmon do not produce the dye themselves, but ingest it with their natural food, which consists of small crustaceans, among other things.

The distinctive red cooked lobster and shrimp is due to the same astaxanthin that gives the salmon its color. However, as long as crustaceans are alive, the color molecule is bound to a protein, which makes the crustaceans appear bluish. The pigment and protein only separate when they are cooked, and the crab or lobster appear "crab-red". But even the crustaceans do not produce astaxanthin themselves, but rather eat microscopic algae, which are the main producers of the dye in the sea.

If the farmed salmon were fed their usual diet, pigmentation would not be a problem for them. But the fish meal, which he has to be content with in aquaculture, contains almost no crustaceans, which is why it lacks the natural reddish pigments. He feels like the flamingos in the zoo, which are also fed dye so that they do not fade.

Most of the astaxanthin used in salmon farming is synthetic. In the European Union it is considered a food additive and has the identification number E161. While in the EU only the synthetic variant has been approved for aquaculture so far, breeders in the USA are also allowed to use "natural" astaxanthin, which is obtained directly from algae or from a red yeast. But the organic version of the pigment is also available in Germany, because the dye is one of the most powerful antioxidants known.

The astaxanthin business is lucrative: The kilo costs around 1,500 euros, and worldwide there are now more farmed salmon than wild salmon over the counter, and the trend is rising. The corporations that manufacture the pigment on a commercial basis do not seem to have to fear any fatigue on the part of the consumer. On the contrary - consumer surveys have shown that buyers are willing to dig deeper into their pockets for dark red salmon, even though the color intensity has nothing to do with the taste or freshness of the fish. And colorless salmon, i.e. fish with a color intensity below 23 on the SalmoFan, is refused by the customer with the same vehemence with which he reviled the colorless cola.

Even if the buyer is informed about the origin of the color in the farmed salmon, his basic attitude does not change: the darker the fish, the more it can cost. This applies at least as long as the color depth varies between a 23 and a 27 on the SalmoFan, i.e. is in the "normal range". Only for salmon, the shade of which has been intensified, does the average consumer no longer want to pay a premium if he knows about the origin of the color. (cs)