This is the end product of the new method and may be used as biogas and fertilizer, as well as a feed for dog teams.
This is the end product of the new method and may be used as biogas and fertilizer, as well as a feed for dog teams. Photo: Jon-Are Berg-Jacobsen/Nofima

Project Year 2013

New method kills pathogens

A new processing method for dead fish from the aquaculture industry leads to reduced energy consumption and products with more uses.

This method can benefit the entire aquaculture industry. In 2012, approximately 1,2 million tonnes of farmed salmon were produced in Norway. Around 5% or 60,000– 80,000 tonnes of the fish die in the cages. The fish are collected daily and preserved on site by grinding and mixing them with formic acid. The fish may have died of various causes, including disease.

Dead fish basically have the same nutritional content as harvested fish, but the risk of the fish containing various pathogens is far greater. Pursuant to current regulations, material from dead fish must be treated with high pressure sterilisation, which is highly energy-intensive and harmful to the products.

“We have carried out several projects to map how much heat is needed to provide adequate killing of relevant pathogens in fish preserved in formic acid,” says Senior Scientist Halvor Nygaard from Biolab at Nofima.

Salmonella and Clostridium perfringens spores were among the pathogenic bacteria studied. The IPN virus, which is the most heat-resistant among known pathogens in fish, has also been investigated. New knowledge about the heat resistance of the IPN virus has made it possible to establish process requirements that ensure safe products.

The new processing method is based on formic acid treatment at pH 4 stored for 24 hours followed by heat treatment at 85 °C for 25 minutes. This method has been tested in industry scale at Scanbio in Bjugn, and is now about to be approved by the EU, after gaining a
positive risk assessment from the European Food Safety Authority (EFSA).

The Norwegian Seafood Federation, Scanbio, Hordafor, Akvaren, the Norwegian Veterinary Institute and NFSA

Rubin, Norwegian Seafood Research Fund

More useful research results