Residue from fish filleting and rapeseed presscakes are currently re-used by manufacturers, but mainly for use in products at the lower end of the value chain, such as animal feed or for energy uses.
High value end products
The aim of APROPOS, which brought together international researchers over a period of three years, was to create practical co-stream products that have a greater commercial value than those currently being produced.
“With growing economies in developing countries there is an increased need for protein, but it is simply not sustainable to increase livestock. We therefore have a need to replace animal-based proteins with plant-based ones, without losing out on nutritional quality or technical performance,” said Raija Lantto, head of biomass and food processing at VTT Technical Research Centre, Finland and APROPOS coordinator.
“The aim was not to produce fractions of high purity, but to develop methods for achieving practical results beneficial to both the producer and the final product.”
Rapeseed presscakes, which contain 10 - 15% unsaturated oil and 40% protein, have a much higher market value when used as food ingredients, estimated at 5000€/ tonne as opposed to 150-300€/ tonne as animal fodder.
Local products for a local market
The project also focused on creating co-stream products that are directly useful for the local economy and population. The team transformed discards from the Nile perch fish, caught in Uganda, Kenya and Tanzania, into dietary supplements intended for the African market, at a time when more than 90% of the East African population lives without a sufficient daily amount of protein and 50-75% of fish is discarded during processing.
The supplement comes in a powder form to be added to low-protein meals. While it has already been tested according to African taste preferences and packaged in portion-sized packets, Lantto said that it was not yet ready for the market but was hopeful it would be soon.
New extraction methods
For rapeseed, VTT developed new bio mechanical methods – which will not be patented – in order to improve the efficiency and sustainability of protein extraction. The treatment used a process of enzymatic hydrolysis to break down the cell walls, thus allowing the protein to be liberated more easily and enabling 50% of the protein of the seeds to be recovered.
This is an improvement on traditional methods of water-intensive protein extraction which rely on pH changes and adding salts to modify the solubility of the protein. In addition, the solvent hexane is often used to extract the residual oil from the presscake at elevated temperatures, which can be detrimental to the technical functionality of the protein.
Other water-based methods are less energy efficient due to the large amounts of water required and the energy used in the drying process.
Other co-streams developed by the project include cold creams and medical dressings from rapeseed and pesticides from mustard seeds.