It smells like a forest after a few days of rain. The smell comes from tightly wrapped blocks with moist straw, which lie on steel racks. Numerous, barely visible dots protrude from the white plastic packaging. “It starts with those warts,” says oyster mushroom grower Mariëlle van Lieshout. “Besides you can see what they will become.” She takes her visitors to an adjacent room. The blocks there are overgrown by bunches of cup-shaped oyster mushrooms.
How long does it take a tiny bud to become a large mushroom? “About a week,” says Van Lieshout, director-owner of the nursery of the same name. Suddenly you get an image of the saying “shooting up like mushrooms”. She shows a time-lapse video that she made of the growth jumps, inspired by nature films.
We are visiting Oyster Mushroom Farm Van Lieshout in Liessel, Brabant, for the meatball of the future. NRC had it designed. This ball is largely plant-based, because eating less meat is healthier and better for the climate. The Brabant oyster mushrooms replace the (partially) omitted meat in the ball and should give it a bit of firmness and a savory taste. More precisely: the stems of the mushrooms have to do this, or the ‘feet’.
Before the oyster mushrooms go to the consumer, the feet are cut off – for the appearance of the mushroom in the store. These cuttings are usually spread over fields or put into animal feed. In parts of North Brabant, Limburg and Gelderland, the mushroom remains are now processed into, among other things, bitterballen, sausages and sausage rolls.
This ‘valuation of residual flows’ is a crucial part of a more sustainable food production, in which cycles are better closed. Carrot leaves are added to the fields as manure, broken syrup waffles go into the pigs’ feed troughs and protein-rich beef blood is mixed with the minced meat. Reusing such leftovers saves money, saves greenhouse gas emissions and land use, and prevents food waste.
Although food waste has decreased by a fifth over the past ten years, it remains high (almost 2,300 kilotons per year in the Netherlands).
Not every residual product yields the same amount of money and climate benefits. Food for people is more valuable than feed for animals, a soil improver more than biogas, which in turn is more valuable than landfill. One residual flow is also much larger than the other. The amount of mushroom remains is (still) modest compared to, for example, the abundance of pulp from sugar beets. Fibers are extracted from this pulp, which are mainly processed into animal feed and to a lesser extent in human food. Sugar beet fiber also comes in our meatball. That’s why we visit its producer later in this episode.
First it will be summer, then autumn
At the Van Lieshout oyster mushroom farm, residual flows flow in and out. This starts with the underlayer on which the fungi grow, the so-called substrate. This is made by a supplier from wheat, rapeseed and corn straw, cocoa bean shells, lime and wood sawdust. Everything is chopped, mixed, disinfected and pressed together with mushroom spores into blocks, which are wrapped in white foil. And the great thing, says Van Lieshout, is that unlike mushrooms, no animal manure is used.
In the nursery, the substrate blocks are moistened and heated by setting the thermostat to 21 degrees. “Then you get heating in the substrate, where the temperature slowly rises to 27 degrees,” explains Van Lieshout. “We’re making it summer in there.” The spores therefore grow in a few weeks into a mycelium, a delicate network of countless fungal threads.
“Then we create autumn by lowering the temperature,” says Van Lieshout. That is the moment when the little buds peek out through the plastic – and in no time grow into banks of oyster mushrooms. In the high season, from September to May, the nursery produces 2,500 to 3,000 kilos of oyster mushrooms per week. Van Lieshout: “When the time for asparagus and strawberries comes, the demand for mushrooms drops – and we grow fewer oyster mushrooms.”
Before the oyster mushroom goes to the store, the feet are cut off.
Photos John van Hamond
Van Lieshout’s mother is harvesting together with an employee. They twist the ripe oyster mushrooms off the blocks by hand and separate the cap from the base with a knife. The hats go into boxes for the supermarket, the feet into bins for the processor – more about that in a moment. Then a new summer-autumn cycle starts in the substrate blocks.
After nine weeks – and two harvests – the substrate blocks are exhausted. The last mushroom caps and feet go into the containers. The leftover oyster mushroom remains are cut from the blocks with some straw and given to a nearby livestock farmer. Van Lieshout: “His cows love it.” What is left goes to an arable farmer, who spreads the mixture over his land, says Van Lieshout: “Initial research shows that the mycelium helps combat nematodes in the soil.”
‘The mushroom has won our hearts’
The destination of the oyster mushroom feet is a few kilometers away, in Deurne. There, a vegetable processing factory houses machines from the company BeefyGreen, which processes 2.5 to 10 tons of mushroom trimmings every week – mainly from the popular button mushrooms, oyster mushrooms and shiitake. “All feet are washed and cut, into cubes or threads – or ground,” says owner Frank Nouwens. And possibly colored with beet juice or malt, for example, to make the mushroom remains look more attractive and to match the color of the product in which they are processed.
Business expert Nouwens founded his company eight years ago, when he found out how much cutting waste there is in mushroom cultivation: “Around 10 to 20 percent of an oyster mushroom, for example, is not used.” BeefyGreen now has contracts with Brabant, Limburg and Gelderland mushroom growers to collect their cuttings. The self-proclaimed ‘mushroom butchers’ use this to develop products that go straight onto the supermarket shelf, such as croquettes, and ingredients for other food factories, which, for example, make vegetarian burgers.
Frank Nouwens, owner of Beefy Green.
Photo John van Hamond
“With mushrooms, food products become healthier and more sustainable,” says Gudrun Kummerer, who is responsible for product development at BeefyGreen. The production of meat releases many greenhouse gases, but hardly any greenhouse gases from mushrooms. Mushrooms contain vitamins, minerals and fiber, and the Dutch now eat far too little of the latter.
“Mushrooms also make products much tastier,” says Kummerer. Because they provide an umami flavor, often described as meaty or savory, and a firm texture. According to BeefyGreen, mushrooms – or better yet: oyster mushroom feet – are perfect for our meatball. “What percentage of your ball consists of oyster mushroom?” asks Nouwens. Five percent. Nouwen: “That is too little. With more mushroom the ball really becomes tastier.”
Sugar beet fibers for the meaty feeling
On the other side of North Brabant, in Dinteloord, trucks full of sandy sugar beets drive back and forth through an empty landscape. The beet campaign is in full swing at agrifood cooperative Cosun, the largest sugar producer in the Netherlands. Sugar beets are one of the most important crops in the Netherlands, but its cultivation has declined in recent years.
Yet Cosun produces almost 1,500 kilotons of beet sugar every year, the equivalent of 1.5 billion sugar packs. This leaves twice as much beet pulp. Food production is the most important source of waste and therefore residual flows.
By processing beet waste, Cosun is the champion of residual flows. In large fermentation plants it produces more biogas from this pulp, where it is one of the largest producers in the Netherlands. The sugar beet processor’s trucks run on this homemade gas. But beet remains are also – and increasingly – an important source of fiber.
We are concerned about these fibres. Sugar beet fiber is increasingly being processed in all kinds of food products, such as partly vegetable chipolata sausages that supermarkets now sell. The fibers, which Cosun markets under the brand name Fidesse, should give our ball some firmness and juiciness, like meat normally does. “Sugar beet fiber is very suitable for this,” says Marcel van de Vaart, innovation manager at Cosun.
Van der Vaart is happy to explain what makes these fibers so suitable, in Cosun’s immaculate food innovation center. “If you cook a hard vegetable, such as a carrot, for a while, it becomes soft. You get a puree.” That doesn’t happen with sugar beet. “You can heat them or freeze them, or do whatever you want with them, but the sugar beet retains its texture. A piece of sugar beet remains a resilient block that can retain water well.”
Due to these properties, beet fibers can give more juiciness to meat substitutes and hybrid products. “Meat substitutes in particular are often very dry and lack a firm texture: you bite into them and they are gone.” Added sugar beet fibers absorb moisture and release it when you chew it. “You feel the moisture being released in your mouth. Then you have to chew a few times to get it away. That gives a meaty feeling.”
When making the sugar beet fiber, the beet pulp is “minimally processed”, according to Van der Vaart. The pulp is cut into long strips and then chopped into pieces. The cubes are otherwise only washed with water and dried. In a jar they look like white, slightly translucent mini fries.
These fiber strips can also improve meat products, says Van der Vaart, because they add fiber and taste: “We believe in a healthy balance of meat and vegetable products. In a comparative test, a panel rated the variant with sugar beet fiber as tastier than the variant with 100 percent meat.”
That promises something for our meatball of the future.
