Long-lasting protein from tomato leaves, fungi and insects

WUR researchers are looking at how to produce proteins in a sustainable and circular way. Theoretically, this is done in a way that avoids competition for food between humans and animals. This is one example of how protein can be obtained from tomato leaves, fungi and insects.

The way we use and consume protein today puts an endless strain on our natural resources, and the problem is exacerbated by the growing demand for animal-based protein. Protein transfer is essential if we are to ensure sustainable nutrition for all on our planet in the future. Wagengen University and Research seeks ways to increase protein supply, diversity and acceptance. Circular systems are an example of how this can be achieved.

In a balanced diet, humans and animals did not compete for food, and any of the direct resources for food were actually used as food. Any source of protein that is unsuitable for humans, such as microorganisms or insects, can be added upwards. Here are some examples of projects WUR is working on in circular protein production.

Protein from tomato leaves
There is a high cost of protein crop residues, but this cost is often negligible and is not used in the food chain. The rest can be decomposed or used for animal feed. The leaves of all plants, such as sugar beet or tomato plant, contain protein rubisco. “At least one-fourth of the protein in the leaf is rubisco,” said Marie Bruins, a senior scientist at protein technology. “This protein is very important to capture and store CO2 from the atmosphere. It is easily soluble and does not bind to anything else in the cell so it can be squeezed from the leaf. But the damage to tomato leaves is that they contain toxins.” The beet grower is currently using the method to extract protein from sugar beet leaves, but Bruns hopes to see it spread. ” There is such an abundance of leaves on our planet, and eventually we want to use all the resources we have to use.

One of the benefits of Rubisco protein is that it can be easily processed into a gel. “This is not the quality you normally find in other plant-based proteins, such as soybeans,” says Bruins. Manufacturers often add eggs as a special structure, which can be useful if used as a substitute for meat or in plant-based dairy products. But this does not mean vegan. “Good plant-based protein is just another potato protein,” says Bruins. “You can also use starch or methyl cellulose, but the product will be high in carbohydrates, which is often not what you want.” According to Bruins, the quality of rubisco jelly is very attractive to food producers. “The nutritional value is also very good. It is only because the extraction process is relatively expensive. That is why it cannot compete with soy, it has a good nutritional value and is very cheap. It is rich in cheap protein such as soy.

There is another test for the researchers, which is that only a certain part of the protein is ready for use. “A large amount is lost during the purification process to obtain a colorless product. When many proteins are released, they turn brown / green, and that is what you want to get rid of. But avoid it. This means you will get a lower protein product. In an effort to improve the extraction process, Bruins is working with researchers from the Plant Growth Team. It is less than the absolute amount of protein and there is a lot that we can actually get out of it, because we only use a small amount at the moment.

Bruns is also exploring the process for other plants as well. “We notice that plant species and species vary. We want to see if we can give that definition. The researchers are looking for opportunities to use fiber from leaf and stem fiber. These can be used to produce packaging materials, for example. “It would be great if we could get to the point where no plants are wasted.”

Mushroom fungi as an alternative source of protein
Another interesting and sustainable source of protein is basidiomycetes, and especially mycelium, a net of fungal fibers. Little research has been done on this subject. “These fungi have the advantage of being able to grow on linoleum, which is something that few other cells can do,” said Karin Schultmeier, a plant biologist. Lignocellulose is a woody material found in all plants, and is the largest renewable biomass on earth.

Schultimeer hopes to produce proteins from renewable biomasses that have not been used in this way before, in the case of existing fungal proteins (such as tempé or quorum) that are self-sustaining. “As a bonus, you don’t need any more land because you can grow it in buildings. And if you only grow mycelium and you do not have to wait for the mushrooms to appear, you will have a shorter production cycle. Schultmeier’s study looked at protein levels in different species of fungi. The researchers produced about 60 species of edible mushroom fungi in a variety of ingredients, including beet pulp, rice straw, cocoa pods, and wood chips. “In all of these species, we see significant differences in protein levels. The fungi produce a lot of free amino acids, which are easily absorbed into the intestines and are important for nutrition. ” Other nutrients in the fungus include fiber, vitamins B and D, and nutrients that boost the immune system. They also come in a variety of textures, scents, colors and flavors.


But before you start using them to do something, it is important to understand how consumers feel about these types of products. Schultimeyer and her team have been researching the issue with colleagues in the social science team. “What we found was that people were definitely ready to eat it, but as a ‘pure label’ food, it was not made as much as possible,” she said. “But if we tell them more about sustainability, they are willing to experiment with other forms, such as flour.”

Future research involves selecting the best fungi for further testing, in part to determine their exact collection. “We want to see if we can use breeding methods to produce better varieties with high protein content,” Schulttmeier said. “Mushrooms say that they are not a good source of protein because their protein content is measured by their dry weight, and mushrooms have a high water content. So if you try to match the protein content of chicken breast, you should eat a lot of mushrooms.

According to Schulttimer, there are still some practical obstacles to overcome before these fungi become part of our main food. “For example, if you grow them on wood chips, you need a way to separate the two because people probably don’t want to get wood chips in their food.”

Reproduction of insects
Insects can play an important role in protein metabolism because they can grow on residues and then be produced by products that can be eaten by humans and animals. “We can’t continue to use soybeans to feed our growing population,” said Esther Ellen, project manager for Insect Reproduction. “Insects have the same nutritional value, but they are more durable because they do not need a lot of land or water, and can grow on the tree.”

However, increasing insects for protein production is still a challenge. For example, products vary. “Currently, insect production is focused on producing larvae and raising larvae,” says Ellen. “Their growth is stimulated by their food supply. But no one looks at the differences between individuals or evaluates which species are most effective.

Reproductive systems may play a key role in promoting insect protein production. Ellen is working on breeding programs and is exploring whether genetic selection can improve protein production in insects. We are not only looking at larvae growth, but also how larvae use their food efficiently and also on health and well-being.

Ellen and her colleagues observed what traits are inherited and how strong genetics are. You need to know this to know what to choose. One of the things we found was that we could choose body weight and ultimately protein production.

The researchers used computer simulation to see what would happen if you did. The first results are promising. The breeding program is tested on the black soldier flies, the most commonly used insect species. “Compared to other animals, such as cows, they are very subtle, because they cannot distinguish between individuals,” says Ellen. “So you don’t know who the parents are.”

A black soldier flies.

The insects are now housed in large groups, and they all mate with each other. Breeders should therefore make some significant improvements in insect habitat and, for example, separate parents. Another problem with black soldiers is that they want to have group sex, says Ellen. You can try to see how the boys are doing, for example, by placing a man with ten females to create lines that will grow better or less prone to disease. The breeders are open to such things, and we are developing a master class in which we can share knowledge and invite them to participate in the process.

Insect breeding – like any other insect breed – is just beginning, but Ellen is excited because we are already thinking about how we want to approach it. “For example, we do not want to choose only production. We also want to think about fertility, health and well-being. We now have the opportunity to gain experience and gain experience in traditional animal husbandry.

Thanks to new EU regulations, insect protein can now be used in poultry and poultry in animal feed. Some insect products are also licensed for human consumption. Although there are some limitations. Residues used in production must be clean, e.g. “Insects are now feeding on what you can feed on farm animals. Eventually, it may be best to grow it on manure or farm produce, such as manure. Then we really had a circular system. The current law does not allow this. Work is currently underway to identify and assess the safety risks of various non-perishable products that cannot be used directly for humans or farm animals.

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Wagengen University & Research

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