Many people are aware that soya beans contain high levels of protein, and that they are often imported to be used as animal feed. Growing soya in Sweden is still challenging, although some trial cultivation is being carried out.
Interest is now increasing in extracting plant protein from various crops such as ley grass, clover, cover crops and the protein‑rich lucerne. Simply put, the plant is separated into two fractions that can be used in different ways.
Green juice
At Alnarp, trials are being conducted in which the crop is first pressed to extract a green juice, thereby separating the fibre fraction from the juice. The fibres can be used as feed for ruminants or as a substrate for biogas production. The green juice is then treated with heat followed by acid. This process yields two types of protein:
- Green protein, which is best suited as feed for monogastric animals.
- White protein, which is suitable as an ingredient in food products.
What remains is a brown juice that is rich in sugars and minerals. It can be used for biogas production, fertiliser or further refinement within the bio‑based economy.Large‑scale biorefinery As early as the 1960s, attempts were made to extract protein from green biomass, but the results were not well received. The products had a bitter taste and a dark green colour that did not appeal to consumers.
Danish biorefinery
Today, the technology has advanced considerably. At Aarhus University in Denmark, a large‑scale biorefinery has been established, and similar initiatives are underway at Sötåsen in collaboration with SLU in Skara, as well as at Alnarp within the project known as the Växtprotein-fabriken.
SLU’s research is also examining how protein can be extracted from ley and cover crops as part of a green protein production system aimed at replacing imported soya in feed and food, increasing self‑sufficiency and reducing environmental impact.
“Research in Alnarp focuses on making use of underutilised green biomass such as lucerne, beet tops and cover crops, which may lead to new sources of protein for both humans and animals,” says Sven‑Erik Svensson.
