Extracting proteins through biorefining
Normally, human beings and other monogastric beings such as pigs, hens and fish are unable to digest grass because of the high cellulose-fibre content. Grass contains as much as 20% photosynthesis proteins, and Mette Lübeck and her research group work to find a method for extracting as much of this protein as possible and subsequently refine them for animal feed and, with even finer refinement, human food.
Our aim is to make every single piece of the plant valuable. This means that we start with a very simple process where we harvest the fresh leaves and put them through a screw press, just as if we were making juice. From this juice we precipitate or extract the proteins by different methods, depending on whether our aim is animal food or human food and how refined we want the end product to be
If the process runs smoothly, as much as 40% of the proteins can be extracted. The leftover fibre pulp can be used for cattle fodder, as it still contains the rest of the valuable proteins. In fact, feeding cattle this processed fodder instead of fresh grass has the side benefit of making the cows produce more milk.
From vegetarian produce to protein bars
Once the juice has been pressed, the researchers have different methods for extracting the proteins. One method the researchers are currently testing is to add lactic acid bacteria: The bacteria eat the sugar in the juice and create lactic acid, which lowers the pH of the liquid to below 4, at which point the proteins can be precipitated. The extracted grass protein, which is at this point digestible by both animals and humans, can be used for a variety of food products. Mette Lübeck has already experienced interest from a wide range of industries – in fact, so much interest that a start up company, BioMassProtein.com, has been established.
We see more and more vegetarian and vegan produce, both for drinking and for eating, and it is natural to consider using grass protein for such products. In the future, maybe we will see ‘grass drink’ next to the soy drink, almond drink and oat drink on the supermarket shelves, or see gluten-free bread made from grass protein
- “Another huge application area is protein bars. We have already spoken to a retailer of fitness products who was interested because it is often difficult for vegans to find protein products without whey. In addition, most athletes want to avoid soy-based products as well, because soy may contain phytoestrogens, a kind of hormones. The retailer was looking into pea and rice protein as replacements for soy, but when they heard of our work in grass protein they saw a new potential way to go” she adds.
Utilizing every last component of the grass
A crucial point for the researchers’ work is that every last component of the grass must be used – either as food, as nutrients or as building blocks for other products in our society.
Once we have created the juice and extracted the proteins, we also need to find a way to make use of the rest of the grass we use. In terms of the remaining part of the liquid – most of which by this point is lactic acid – this can be used as a component of a type of bioplastics, but we also need to look into further use of the plant pulp that is left once the juicing is done. If we get a major production up and running, we will in fact have more pulp than can be consumed by cattle
One potential use is as biomass for energy production, but she hopes that in the future, grass fibres may also be used for composite materials, textile fibres or bioplastic for coffee cups and other household items.
Huge potential for sustainable farming
However, the researchers’ work does not only focus on the methods for turning grass into food and fodder. They also work on the larger perspective of supporting sustainable and eco-friendly farming by making grass a sought-after and valuable product, which at the same time contributes to a sustainable nutrient cycle.
- “In essence, we approach the refining challenge with a focus on 1) using every single fraction of the plants we use, 2) thinking in terms of nutrient cycles, and 3) making grass production financially viable for the farmers, because if they cannot run a profitable business on the basis of it, they simply will not grow it” Mette Lübeck says. Grass blends that include clover grass and alfalfa belong to a plant family with the ability to fix nitrogen from the air, which is why they have such a high level of protein. This means that in terms of crop rotation, farmers can use these grass blends as a natural way to fertilize their soil. After one or more years of growing grass on a field – which will be ploughed down once it is time to rotate to a new crop – the soil will have a high level of nitrogen too, and the farmer will not need to fertilize the fields as much as would otherwise be necessary.
- “We are actually looking into utilizing this fact in our refining processes as well: Once we have extracted the proteins we need for food, another way to use the leftover juice is to filter or evaporate it to get the nutrients nitrogen, phosphorous and potassium. These are the exact ingredients of a widely used fertilizer called NPK fertilizer, and as such we can return these grass components to the fields in order to provide the minerals that farming needs. In this way, we can create a sustainable nutrient cycle” Mette Lübeck says and emphasizes that this kind of fertilizer can be used in organic as well as conventional farming. In addition, the use of grass as a crop helps reduce the leaching of nutrients from farming into the ground water.
- “A further advantage in terms of protecting our environment is that farmers can grow grass for maybe as much as four years – instead of the usual crop rotation every year if they grow grains, corn or potatoes – which lets the grass develop a stronger root net. This in turn means that the grass will retain a larger amount of nutrients from the soil, which might otherwise have leached into the ground water once the grain crop had been harvested and the field left bare until next crop” Mette Lübeck explains.
Methods also viable for third-world crops
Another – and maybe the most important – aspect of enabling the use of grass and similar green plants as human food is the fact that the researchers’ refining methods can be used not only in advanced first-world countries but also in third-world countries where food is scarce.
- “I fully believe that the methods we are developing will be able to help fight hunger. In Africa, for instance, many poor people live off the cassava plant – but what they eat are the roots. Most of the plant’s protein content is in the leaves, but up until now they have mostly just been burned as a waste product” Mette Lübeck says and finishes: “If we can turn these leaves into food as well, we have a huge new food source for these people. In addition, different types of grass can also be grown in those parts of the world, and if we can enable these resources as food, we can help these countries get more self-sustainable, both in terms of food and in terms of fodder for their farming animals. At this point, our work will have helped these people and countries, it will have helped farmers all over the world – and it will have helped our climate” Mette Lübeck finishes.