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Cod fillet – fresh and nematode-free

In his PhD project, Nofima scientist Agnar Sivertsen has developed a new system for automatic inspection of cod fillets known as hyperspectral imaging. As well as detecting unwanted elements, the system can provide information about how fresh the fish is.

Manual trimming and inspection of cod fillets is currently regarded as the most time-consuming and expensive aspect of fillet production in Norway, accounting for nearly 50 percent of the production cost.

Automatic control

Most aspects of fish processing in Norway are mechanised. But inspection and trimming is still manual, and often creates a bottleneck in the production line. Nematodes are regarded as the most important element in a fillet to detect, but also the most difficult.

This manual work is often carried out in temperate areas, where the product can be exposed to enzymatic and microbiological influence and subsequent downgrading. The Norwegian fish processing industry can now be offered a better solution for automatic control of fillet, with the main focus on cod.

Fresh or frozen?

The new system is able to transilluminate the cod fillet, skin on or skin off, and can automatically detect nematodes and in which part of the fillet they are located. At the same time the fish is checked to determine how long it has been on ice and if it has been frozen, all at a rate of one fillet per second.

Fish right on our doorstep

Owing to high labour costs in Norway and difficulties with recruiting workers, an increasingly higher proportion of the catches is frozen and exported to other countries with lower production and labour costs.

Back in Europe as a finished product they compete with products produced in Norway, and as a general rule are sold at significantly lower prices. Norwegian producers have to reduce the high labour costs if they are to be in a position to compete with the countries with low production costs. However, the fish producers in Norway have a major advantage – proximity to the fishing grounds. This can provide the Norwegian fishing industry a new opportunity to cut production costs and retain the fish in Norway.

Many systems tested

As far back as the early 1990s, systems have been tested using different lighting to detect unwanted elements in fish, but these had their limitations. Other things such as fish scales, bone and connective tissue have often been interpreted as nematodes, and nematodes deep in the fillet have not been detected.

The previous methods were also too slow for industrial conditions, and were never incorporated in industrial production. A typical processing speed is a rate of one fish per second, which requires a production line with a speed of 40 cm per second. The new system has now solved this.

Agnar Sivertsen, who has a Master of Science, will present and publicly defend his PhD thesis entitled “Automatic Inspection of Cod (Gadhus Morhua L.) Fillets by Hyperspectral Imaging” at the University of Tromsø on Friday, November 11. Supervisors for the PhD project have been Senior Scientist Karsten Heia and Director of Research Heidi Nilsen at Nofima and Professor Fred Godtliebsen at the University of Tromsø.

The PhD project has been financed by the Research Council of Norway, the Fishery and Aquaculture Industry Research Fund (FHF) and BAADER.