There’s more to fish than just food, and thorough use of fish parts benefits both traditional and circular economy. The full potential of fish-based added value products hasn’t yet been harnessed. Luke’s researchers give their view on how unused fish parts could be exploited.
Fish skin contains collagen, a protein that is used in, for example, cosmetics to increase skin elasticity and strength. Collagen can also be turned into gelatine which is utilised in foodstuffs, like gummy bears, as a gelling component.
Fish skin can also be cured and tanned for leather products like handbags or shoes. This can give new life to the skin that would otherwise be thrown away. As innovative as it sounds, the phenomenon is still in its infancy.
“The utilisation of fish leather is still somewhat amateurish”, says Pirjo Mattila, Principal Scientist at Luke.
Fish scales contain chitin, organic material that can be transformed into chitosan. Chitosan has multiple applications for biomedicine, dietary supplements and agriculture, for example. It has properties that help to prevent blood clots and protect plant seeds, to name a few examples. The most extreme applications include using chitosan as a repairing material for car paint coatings.
Chitin is generally extracted from the shells of sea crustaceans. So far the only chitin available in Finland has been imported. Thus there still lies significant potential in the production of chitosan from Finnish fish.
Fish bones are an excellent source of different minerals, such as calcium and phosphorus, and contain also collagen. The minerals can be used as raw materials in the chemical and fertiliser industries.
Phosphorus is a commonly used fertiliser: it has a positive effect on the development and growth of plants. Unfortunately the flow of phosphorus from fields to waters causes eutrophication. By obtaining phosphorus from fish bones the circle can be closed.
“This can be a way to recycle phosphorus: it moves back from waters to fields”, Pirjo Mattila points out.
Fish oil has a favorable fatty acid composition. It is rich with omega-3 fatty acids that contribute to, for example, the development of the brain, central nervous system and sight.
Fatty acids aren’t the only component in fish oil beneficial to the health. The oil contains many vitamins, such as vitamin D, which is a crucial building material for bones and teeth.
The health benefits of fish oil can be enjoyed as dietary supplements in the form of tablets or liquids.
Fish waste refers to the parts that are left over when fish are processed for food: skin, viscera, head and bones. In Finland a vast part of fish waste ends up as an ingredient in animal feed.
“The importance of the fur industry for the fishing industry is surprisingly big. The amount of fish waste from baltic herring and sprat put together is 140 million kilos per year. 40 percent of it was used by the fur industry”, explains Jari Setälä, Senior Scientist at Luke.
Fish waste can also be used for producing biodiesel or biogas.
Proteins and peptides
Fish are an excellent source of proteins with high nutritional value. Moreover, structural parts of the proteins called peptides, can have various positive bioactivities, that is effects on living tissues. These include e.g. antiviral and antimicrobial effects. Fish peptides can even lower blood pressure and relieve pain. Fish peptides have already been commercialised. However, there are no Finnish manufacturers of these products so far.
Other fish protein products could also be of good use. “There’s a huge protein boom going on at the moment. Fish protein could be more widely used to produce protein supplements”, says Pirjo Mattila.
Text: Kira Keini / Kaskas Media