Sissel Albrektsen has found that minerals from fish bones make it much easier for salmon to digest and absorb astaxanthin into the flesh. Photo: Bjørn Erik Larsen © Nofima

Project Year 2018

Fish bones give more red salmon

 Nutrition and feed technology  

A mineral-rich ingredient that Nofima scientists have made from fish bones has had unexpected effects.

Salmon fed the new ingredient had much redder muscle. The effect, which was first observed in an experiment with salmon smolt and visible to the naked eye, has been confirmed by chemical analysis.

The colour came from astaxanthin, a pigment that is added to salmon feed to ensure the distinctive red colour. Usually less than 10% of the astaxanthin in the feed is absorbed into the muscle of farmed salmon, mostly due to oxidation of astaxanthin into colourless compounds, but also due to limitations in absorption and transport of astaxanthin into the tissues.

Nofima’s mineral ingredient contains minerals extracted from fish bones.

Surprised and very positive

The experiments showed 35% more colour deposition in muscle of salmon fed with the mineral ingredient, and ability to digest astaxanthin increased by nearly 20%. Pigment levels in the blood and liver also increased.

“It is surprising and very positive that a mineral ingredient can affect pigment utilization,” says Sissel Albrektsen, a senior scientist at Nofima.

She and her colleagues at Nofima have long researched effective ways to exploit fish bones. They used an acid to extract minerals from the bones of blue whiting. Increased astaxanthin utilization is a very positive side effect with high market value.

Increases digestibility of astaxanthin

Feed containing the phosphorus-rich mineral ingredient was tested on salmon of 1.7–2.5 kg, and compared with salmon that received the same feed containing a common commercial source of phosphorus.

“We believe that the main explanation for the redder muscle is that the salmon digest more of the astaxanthin with the mineral ingredient in the feed,” says Albrektsen. Albrektsen and her colleagues are now going to study how minerals extracted from fish bones can affect intestinal function.

The Research Council of Norway (FORNY)

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