Grønt proteinpulver fra lucerne. Foto: DTU Fødevareinstituttet

Protein from green biomass without the taste of cowshed

Food and fisheries Food technology Food production
Researchers from the National Food Institute, Technical University of Denmark, have developed the technique and purchased the equipment that allows them to produce sustainable green protein for food use without unwanted off-flavour on a pilot scale.

Cows like the grass to taste like grass. However, if people are to eat sustainable protein extracted from green biomasses such as ryegrass and alfalfa, it is crucial that it does not have a taste profile, which some people describe- while wrinkling their nose –as ‘cowshed’.

This fact is well known by researchers from the National Food Institute, who have been working in various research projects for the past four years to extract protein from sustainable, green biomasses. They do this by extracting protein-containing liquid from the biomass before drying it into powder, which can be used in various foods.

Supercritical CO2 is The Holy Grail

Food producers can use aromatic ingredients to camouflage the powder’s off-flavour, or they can use techniques to remove it from the powder.

The first solution is seemingly the easiest, but it also forces food producers to use certain ingredients to conceal the grass taste. Tasteless powder, on the other hand, would give producers free rein when it comes to formulating of the recipe. However, this solution is quite demanding in terms of technical skills and researchers have struggled to find useful techniques to remove the taste. 

In fact, researchers in this field describe the removal of the unwanted taste as “The Holy Grail”. Nonetheless, it seems that researchers at the National Food Institute may have found it: The institute’s researchers have succeeded in removing most of the hay smell and cowshed taste by using a supercritical CO2 extraction system to treat protein mass made from alfalfa.

A supercritical CO2 system works by bringing CO2 into a supercritical phase by bringing the gas above 70 bar pressure and above 33°C. In this phase, CO2 constantly switches between being in the gas phase and the liquid phase. This enables the gas to penetrate particles - such as the green protein - and extract flavors and aromas from the protein without altering its functional properties.

The technique is not new. It has been used safely for more than half a century to e.g. remove caffeine from coffee and flavorings from hops. Once the protein from the green biomass has been treated, it can be used in foods where soy protein has been the primary source until now. Swapping the protein sources reduces the climate impact of food.

Larger plant enables larger scale production

Until now, the National Food Institute has only had  small-scale supercritical CO2 extraction system at its disposal, which researchers have used to determine the settings needed to remove the powder’s taste and fragrance.

With funds from the research infrastructure FOODHAY, the institute has now purchased a larger plant that can handle much larger amounts of protein powder. The National Food Institute sends the treated powder to its project partners, who incorporate it into various food products that will then have a lower climate footprint.

FOODHAY was established to help in the development of healthier and more sustainable foods and the reduction of food waste. The funds for FOODHAY come from the Danish Ministry of Higher Education and Science and a consortium consisting of Aarhus University, DTU, the University of Copenhagen, Arla and the Danish Technological Institute. FOODHAY’s total budget is 103 million Danish kroner.

Expecting an easier path to novel food approval

The green protein has not yet achieved novel food status. However, the researchers at the National Food Institute expect that the road to approval will not be as long as for other novel foods given that the European Food Safety Authority, EFSA, has already deemed the whole alfalfa plant safe for human consumption. A protein concentrate from the plant has also been approved as a dietary supplement.

Read more 

The Research Group for Microbial Biotechnology and Biorefining at the National Food Institute focuses on efficient bioconversion of a wide range of sustainable raw materials. Read about the group’s work on the National Food Institute’s website.


Grass is easy and cheap to produce in Denmark. Farmers grow it throughout the country in large quantities together with nitrogen-fixing crops such as alfalfa and clover, which helps to prevent nutrients in the soil from leaching into waterways.

The amino acid composition of grass protein is similar to that of other protein sources such as soy, eggs and whey. However, producing grass protein has a considerably smaller impact on the environment and climate.