Cod heads and chicken carcasses rise in value

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By Milthon Lujan

Norway.- Each year around 35,000 tonnes of chicken frames and 72,000 tonnes of cod heads are produced as a result from Norwegian food processing. These by-products contain many valuable components that should be better utilised. Through the Notably project, researchers plan to make this happen.

Today, some of the cod heads go into producing animal feed, while another portion is dried and sent to Nigeria, where soup is made from them. The part that goes into Nigerians soups has declined over the years, and the market has shown to be unstable. This is unfortunate, because cod heads contain many valuable nutrients.

‘We have to stop looking at these as surplus materials. This is a food source on par with every other food source, Nofima researcher Diana Lindberg says.

Cod heads and chicken frames in fact contain minerals and different types of fats, not to mention many different types of proteins. Much research has already been done showing that there are many different uses for these components, from pet feed to functional foods and medications. One interesting component is collagen, a protein that in its purest form can potentially be used in everything from skin moisturizers to health food, and which is also the source of gelatin. Researchers will now examine how most of these components can be extracted through multistep processing, so that the value of these raw materials is maximised.

Better processing

Slaughtered chickens are split up and sold in various parts. These may include breast fillets, drumsticks and chicken wings. Imagine instead that all the chicken meat had been ground up into minced chicken meat. This would result in a much lower price per kg than from selling fillets and wings separately.

This can be likened to the way chicken frames and cod heads are handled today. Everything is ground up and processed, or dried and sold as is, usually for animal feed. This is what researchers in the Notably project want to change. They are examining how the use of additional and more refined processing steps can contribute to better extraction of all components in the raw material.

Currently, protein and oil are extracted together in a one-step process by use of enzymatic protein hydrolysis. This single-step process makes it impossible to utilise all the valuable components found in the raw materials.

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‘We want to resolve this by combining several different steps in the processing, and the goal of each step is to separate the individual components, targeted towards market where they have the greatest value’, says Nils Kristian Afseth, senior researcher at Nofima. He is the project manager for the Notably project.

New technological solutions

Each processing step must be developed so that at each stage along the way, you end up with the desired component of best possible quality. In this respect, the enzymes one chooses is a key factor. Using this approach, you can set up a series of processing steps, a cascade, where processing of the various components runs in a sequence until all the components of the raw materials have been extracted as optimally as possible.

This is not unlike what you see in biorefineries such as Borregård in Norway, where wood is the source of a series of different products, or in oil refineries, where the oil ends up in a range of different products from natural gas to asphalt.

The researchers think that this type of cascade processing can either take place in many individual steps, but it might also be possible to perform this in the same reactor. For example, to develop multiple-step processes in a reactor, it is necessary to use different enzymes that must be “shut down” or “locked” when not needed, and “turned on” or “unlocked” when there is a need to use them. Researchers at Sintef Industry will work with this development.

The biochemical reaction that occurs in one processing step will affect the next step in the cascade process. The researchers will therefore work with rapid sensors that can be used to determine the mass balance of what goes in and out of the process. In addition, it would be important to use thorough, rigorous bioanalytical methods to understand what is taking place during each processing step.

Will simulate what will happen on a large scale

The scientists do not yet know exactly how the new technological solutions will look, but they do know that it does not take much to destroy valuable components while processing. Although the hydrolysis process works in a small scale, there might be pitfalls on a large scale. Researchers at Simula have the task of developing computer simulation models that are able to quickly, affordably and safely answer whether an upscaling will succeed or not.

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‘In theory, the equations enabling us to design successful refining steps will work on both a small and a large scale, but the biochemical reactions might be different and we will have to take these into account. Imagine that you have one small and one very large kettle. It is much easier to stir and to obtain a smooth blend in the small kettle. In the large one, for example, gravity will most likely cause the mixture to separate. The same occurs in upscaled hydrolysis processes’, Kent-André Mardal, senior researcher for Simula and professor at the University of Oslo, explains.

Kent-Andre and his colleague Simon Funke’s job will be to develop computer simulation models that map and test what conditions need to be accounted for to be able to reach a successful relevant multi-step processes in a large scale.

Cod heads rise in reputation

The Karlsen Brothers operate on the seashore at Husøy by Senja island. Most of the codfish here is preserved as salted cod. Currently cod heads are either dried or turned into animal fodder.

“We know that many of the nutrients in the cod heads are as important to humans as they are for animals, and we are looking to get more into the human consumer market, with new products. This will both provide greater value for us and make better use of the cod heads’ healthful substances”, Karl Kristian Eilertsen, of the Brødrene Karlsen company, says.

With the aid of new technology, their hope is that the useful nutrients in the cod heads will find new markets in the future.

‘Our goal is to make sure that both cod heads and chicken frames are better utilised, so that we can contribute to higher value creation for food producers and ensure that the food we produce is utilised in the most sustainable manner possible,” Nils Kristian Afseth concludes.


Hydrolysis is composed of the Latin words hydro, meaning water, and light/lysis meaning breakdown, that is, a breakdown caused by addition of a water molecule through disintegration or splitting of proteins by water and enzymes. Selected enzymes are used to cleave the peptide bonds in the protein chains into smaller peptide stretches called peptides, or single amino acids. This makes the proteins easier to digest, and at the same time changes the functional properties of the original proteins.

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Enzymatic protein hydrolysis also occurs in the human digestive system. Pepsin, the digestive enzyme found in gastric juices, can also be used in industrial protein hydrolysis processes.


Notably is the short name for the project ‘Novel Cascade Technology for optimum utilization of animal and marine byproducts’. The project will run four years, from 2018 to 2022. The project is funded by the Research Council of Norway under the BIONAER programme. Partners are Sintef industry, Simula, Lund University, Brødrene Karlsen, Biomega Group, Norilia and Bioco.

Contact person
Nils Kristian Afseth
Senior Scientist
Phone: +47 958 40 641

Diana Lindberg
Phone: +47 913 00 486

Source: NOFIMA

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