A change in how fish are processed could reduce the use of packaging and transportation by 20 percent, and cut 15,000 truck trips from Norway to Europe each year, according to new research.

Subcooling -- a method that entails quickly reducing the temperature of fish right to the edge of freezing -- offers the same or even better levels of preservation than icing, but makes room for more fish per crate.

Fish does not freeze until it reaches a temperature of between -0.5 and -1.5 degrees Celsius -- subcooling takes temperature down to just below 0 degrees Celsuis.

Subcooling can be done by various methods including subcooled liquid, dry ice or other freezing technologies.

According to the report, subcooling can reduce the cost of packaging and distribution by about NOK 70 (€0.07/$0.06) per kilo for road transportation from Norway to Europe and NOK 2.70 (€2.50/$2.70) per kilo for air shipping, leading to huge savings for salmon farmers.

Greenhouse gas emissions related to processing, packaging and transportation could be reduced by around 15 percent for salmon that goes by trucks to Europe and around 17 percent on salmon that is flown to Asia.

The report was commissioned by the Norwegian Fisheries and Aquaculture Industry, and published by researchers Audun Iversen, Bjorn Tore Rotabakk and Friederike Ziegler.

Nofima researcher Audun Iversen. Photo: Robert Nedrejord

"In the experiments, we mainly cooled the fish down to almost freezing point and used some of the water in the fish, as salmon contains 65 percent water, which then becomes part of the ice," Rotabakk explained to IntraFish.

Standard polystyrene boxes insulate well at zero degrees and keep the temperature for six days, Rotabakk said.

Large parts of the potential cost savings comes from removing the cost of producing ice as well as the extra space it gives the product. In a standard box, there are usually 20 to 22 kilos of salmon and between 4 to 5 kilos of ice.

The researchers also say that subcooling improved the quality of the salmon in their tests.

"If it's done correctly, it provides better microbiological quality and longer shelf life," Rotabakk said.

Nevertheless, there are naturally some challenges.

The ice used today offers more than just chilling the product. If there is still ice in boxes on arrival, it is seen as an instant visual proof that the cold chain has been maintained.

The industry would need to adjust the buyer mentality of this gauge of freshness by taking the temperature of the fish on arrival, Rotabakk said.