Fish side streams boost plant foods

A new PhD thesis from Norwegian food research institute Nofima has highlighted the potential to use fish-industry side streams in plant-based foods, with modern processing technology helping turn underused marine resources into nutritious ingredients.

In Norway, cod and salmon fillets are popular, but as much as 60% of a fish can be discarded during processing. These side streams, including heads, backbones and skin, are mainly used for animal feed, fertiliser or biofuel despite containing valuable proteins, minerals and healthy fatty acids.

“Ideologically, my choice comes down to resource utilisation,” said Liv Helene Sickel of Nofima, who defended her PhD thesis at the University of Bergen on 11 September 2026.

Her research examined whether salmon and cod ingredients from side streams could be combined with pea protein and wheat gluten to create nutritious hybrid foods. The ingredients were processed using high-moisture extrusion, a technology capable of producing a fibrous, meat-like structure.

The study found that increasing the proportion of fish generally produced a softer texture, although the result depended on the ingredient and processing conditions. Salmon protein hydrolysate, for example, contained proteins broken down into smaller components that behaved similarly to water during processing.

This indicates that protein concentrate could partly replace water without significantly altering texture while increasing nutritional value. Cod protein powder also softened products, but higher processing temperatures compensated for the effect. Products containing 25% fish could therefore achieve a texture similar to a plant-based reference sample.

“By creating opportunities to use more protein from fish we have already harvested, we could give the fishing industry an incentive to take better care of the raw material and use it in food,” Sickel said.

The findings could support the development of products such as burgers and nuggets while increasing the value of marine resources currently directed towards lower-value applications.

Sickel’s research was conducted through Nofima and the University of Bergen as part of the HybridFoods project, which explores hybrid foods addressing future sustainability and health challenges.