Automatic detection of parasitic nematodes in cod fillets

Using HySpex Baldur, Lerøy and Nofima have developed an automated detection system, as a part of their quality assessment line to ensure their cod filets are free from parasitic nematodes.

Parasitic infection of nematodes is a challenge to the white fish industry as fish products with visible nematodes are not accepted for human consumption. The wormlike creatures are a cosmetic problem that can significantly affect fish acceptance and cause a general aversion against white fish. The nematodes can also cause a health risk when eating fish that has not been frozen or adequately cooked. Today every single fillet is visually inspected by transillumination on candling tables and nematodes are removed manually. This is an expensive and time-consuming operation that can account for as much as half of the production cost for Pacific cod. The manual detection efficiency can be as low as 50% under industrial conditions and only 25% for fillets with skin. Nematodes embedded deeper than 4–6 mm are not detected by manual inspection.

Nematode in fish Inspecting for parasites

 

Using HySpex Baldur, it is possible to automatically detect nematodes in cod fillets with a detection rate that is comparable or better to what is reported for manual inspection. The small size of the nematodes makes the cameras from HySpex ideal for this application with its high spatial resolution and image quality. The system can operate at a conveyor belt speed of 400 mm/s which meets the industrial requirement of assessing one fillet per second. This can reduce the workload for the trimmers significantly. The reduced manual handling of the fish will also have a positive effect on the quality and shelf life of the products and there is a potential for a waste reduction due to more precise trimming. The system is under further development in a new research project where both speed, detection rate and detection accuracy are expected to be improved.

The camera setup can in addition to nematode detection be used to monitor other quality parameters in fish like blood content and catch injuries giving the possibility for fully automated quality inspection.

Detection results