In biorefining, green raw materials are processed into new, high-quality products: different components are separated that have a higher value separately. For example, biorefining makes it possible to produce proteins from grass, among other things, available for various purposes. And that offers many benefits for the environment, for the agricultural sector and for the local economy.
An important part of the Dutch agricultural area consists of grassland. That grass is largely intended for cows, the only ones who can digest this grass with their multiple stomachs. Mono-gastric animals, such as pigs, chickens and humans, cannot and they need to fulfill their protein needs differently. Pigs, for example, receive high-quality proteins mainly in the form of soy meal, which is imported from Latin America. Grass protein has a similar composition to soy meal and is therefore an excellent soy substitute if it is processed properly: with biorefinery.
In addition to grass, other green crops are also suitable for biorefining, such as beanplants, sugar beet and tomato leaves, vegetable processing residues such as broccoli stems and invasive aquatic plants such as the large pennywort or hyacinths. These green raw materials, which are usually seen as waste, can also become excellent sources of protein.
How are proteins extracted?
In biorefining, the green raw material, for example grass, is first crushed and pressed; the juice is separated from the fibers. The fibers, with part of the proteins present in the grass and very suitable for cows, can be packed airtight, so that they are preserved as silage. Part of the nutrients are part of the juice. These are proteins, sugars and minerals. The juice can be further processed by separating and concentrating its proteins. We name the liquid that remains the “whey”, by analogy with the milk industry. The “whey” can also undergo further treatment. Phosphate is still in the solution and can be removed. The low-phosphate residue is then separated into a sugar-rich fraction, a mineral-rich fraction and clean water.