New technology developed by Nofima, allows better utilisation of each individual fish and better profitability for the fishing industry. PHOTO: AUDUN IVERSEN ©NOFIMA

Project Year 2017

Bloody serious about quality

 Seafood industry  

An advanced light meter will revolutionise the processing of fish. Light is being shone on the bloody truth about quality.

The fact of the matter is that white fish can be sorted according to the amount of blood in the fillet – now without having to resort to a knife. New technology developed by Nofima allows better utilisation of each individual fish, and better profitability for the fishing industry.

“We have been working for some years to develop an efficient method of ascertaining quality that can be used on both white fish and red fish, like salmon and trout. Now we have hit the jackpot. We hope to launch a prototype sorting machine that the industry can start using in 2018,” says senior scientist Karsten Heia.

Grading fish flesh with light

The key is spectroscopy.

“In simple terms, spectroscopy is a method of measuring using light. Light is passed through a fish, and we have devised a way to work out how much blood is in the fish muscle, based on how much light is reflected back. Various elements inside the fish absorb light, and we can now identify how much of the light loss is caused by, say, blood,” Heia explains.

For example, it is also useful for producers of red fish to know the fat content of fillets and whether they contain unsightly melanin spots. Spectroscopy can do all this as well.

Whole fish

“We can scan white fish whole, i.e. without cutting them open. We know that 30–40% of the fish landed have a high percentage of residual blood in their flesh. Now we can remove these fish from the production line at an early stage. It is very expensive to send inferior fish for filleting only to discover the real quality there,” explains Heia.

Consumers expect high quality white fish to be white. A pink or red fillet means too much blood has entered the muscle. This generally occurs because of stress or injury during capture or slow processing on board.

“Blood in fillets is really only a matter of aesthetics. The fish tastes exactly the same, but consumers are not willing to pay as much for it. If the quality can easily be ascertained before the fish enters the filleting line, it can be processed on the basis of the price it can command in the market. This will also make it easier to reward fishermen who land good-quality catches,” the scientist adds.

Profitable grading

Red fish like salmon and trout are a bit more complicated, since both the blood and the flesh are red, so here Nofima’s method works best on fillets.

“For example, if you make smoked salmon out of a filet that contains a lot of blood, there will be black spots in the final product. This is normally not detected until you start slicing up the salmon. In other words, you will have made a product you cannot sell at full price, even though you have used exactly the same resources to produce it as the ones you can sell at a normal price,” says Heia.

In the past, producers have resolved this by buying 25–30% more raw material than they need, because they know that a certain percentage will have to be sold at a lower price.

With spectroscopy, they can determine the blood content of fillets before they start smoking or curing them.

The scientists are currently working with equipment suppliers and the industry to develop a commercial product from this method, in collaboration with domestic and international business partners.

Nofima –Strategic Research Initiatives

With a view to providing businesses with the expertise they need to deliver top-quality products, Nofima is developing world-class research in selected areas. Spectroscopy is one such area, and through the Strategic Research Initiative “Spectec“, scientists are working to improve and develop new and better rapid measuring methods using light.

Regional Research Funds North

More useful research results