Previous feed trials carried out on rats have shown that fish proteins can affect the development of obesity in rats. Researchers at NIFES are using fish protein hydrolysate to examine how fish proteins affect lifestyle-related diseases in rats, where the rats function as a model for humans. The nutritional content has now been mapped.
- A sound understanding of the nutritional composition of the hydrolysate in the feed is important in order to find the underlying and fundamental causes of, among other things, the development of obesity and diabetes in rats in feed trials, says researcher Bjørn Liaset at NIFES.
- This knowledge enables us to design defined experimental diets and to examine the biological responses in the animals which are fed these diets. As such, an overview of the nutritional content can be a useful tool for researchers working with fish protein hydrolysates in nutritional studies.
While previous analyses have focused mainly on the functional properties of the hydrolysates, these analyses provide a comprehensive overview of the nutritional content. Among the findings, the analyses show that fish protein hydrolysate from cod, Atlantic salmon and saithe contain high levels of the amino acid taurine, the trace elements iodine and selenium, and B vitamins.
The role of nutrients in the body
B-vitamins are involved in metabolic processes, including energy metabolism. The trace elements selenium and the amino acid taurine act as antioxidants. This means that they protect the body’s cells against harmful by-products created in the metabolism of nutrients. Taurine can also lower blood cholesterol levels. Iodine is an element that is necessary for the normal functioning of the thyroid gland, which in turn is involved in regulating the body’s metabolism. Iron is important for several of the body’s functions, including the transportation of oxygen to the cells. Zinc is also important for the immune system.
Where does the raw material and hydrolysate come from?
Each year, the fish processing industry produces large quantities of residual materials which have been largely used for the production of silage, a low-price product. Using enzymatic hydrolysis, it is possible to separate peptides (chains of amino acids of varying length) from this residual material. On completion of the process, three or four fractions are left: fish protein hydrolysate (soluble fraction), a solid by-product (insoluble fraction), and bone and oil (of the raw material contains fat).
Hydrolysis is a chemical reaction during which water molecules are split during absorption of water. During enzymatic hydrolysis nothing is therefore added to the fish meat other than enzymes and water. The hydrolysis process causes the proteins in the fish meat to split and shorten. The peptides arising from the hydrolysis, can be separated from bones and fish oil and in isolated form, these peptides constitute the main component in fish protein hydrolysates. Fish protein hydrolysates might have a high nutritional value.
Other uses of fish protein hydrolysate
Fish protein hydrolysates are currently used in animal feeds, but may in the future be used as a functional ingredient in specialised animal feeds or in drinks and food products for human consumption.