In order to produce functional protein ingredients from complex bony raw materials such as fish filleting side-streams, the so-called pH-shift process is a promising technique, which is now evaluated in the WaSeaBi-project.

This technique was patented for protein recovery from fish around the millennium shift, but has in the last 10 years been substantially improved and adapted to many challenging marine raw materials through work carried out at Chalmers University of Technology in Sweden. Its great potential lies in the possibility to directly use the whole complex raw materials, without any pre-separation of muscle.

Since the process is done cold, the proteins maintain their ability to form a gel network, a very important property to formulate a food product. The process also offers great possibilities to recover and add value to the residual fractions of used filleting side-streams, i.e. bones, skin and oil, which allows it to be used as a true biorefinery tool.

In the WaSeaBi project, the pH-sift process has been applied to cod filleting side-streams from Royal Greenland and to herring filleting side-streams from Scandic Pelagic.

What are the results?

The primary results have verified the high efficiency of the pH-shift process in selective extraction of proteins from sorted and unsorted filleting side-streams from white muscle fish and pelagic fish. The latter were also tested after a pre-stabilization treatment using antioxidant solutions.

The recovered proteins have retained their functional properties such as gel-forming capacity which allow their direct application as a sustainable surimi or mince substitute in restructured seafood products such as fish burgers, fish balls, fish cakes, fish sausages, etc.

How can the results be used?

The results can help the fish industry in their side-stream management by aiding their selection of input materials and pre-stabilization methods to assure the best possible end products. This is not least critical for successful application of the pH-shift process in order to add value to fish filleting side-streams via the production of high-quality and sustainable aquatic proteins.

See how the pH-shift process is used on cod side-streams at Chalmers University of Technology in the video below.