Food Science

The Mushroom Boom

  • Why it matters

    Why it matters

    The mushroom business generates revenues of more than $30 billion worldwide and is growing by 10 percent a year, according to one estimate.

  • Facts


    • At the University of Giessen,  researchers are studying how mushrooms create aromas and how they use waste.
    • Myco-protein, or mushroom protein, is sold as an alternative to mincemeat, sausage or thin slices of meat, mainly in Britain, Scandinavia, the United States and Switzerland.
    • In some stadium-sized growing facilities, remote control-operated lasers and picture-recognizing robots learn how to pick mushrooms.
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Die Pilzsaison hat begonnen: Steinpilzernte
Of the approximately 1,600 mushroom species in Germany, only a few are edible and tasty, such as these wild-growing porcini. Source: DPA

Deep in the woods outside Frankfurt, the organic farm “Druid Austernpilze” is located on a former military base. It specializies in oyster mushrooms – large, floppy fungi that were first grown in Germany to feed people during World War I.

Every year, organic farmer Georg Heinrich Rühl grows 400,000 kilos (880,000 pounds) of organic oyster mushrooms. And these days, business is booming.

Mushrooms are having a moment in Germany. The gourmet, sustainable foodie trend has seen more and more restaurants offering them in meals as fresh and healthy fare direct from nature. Mushrooms are full of protein, low in calories and an excellent option for vegetarians.

For organic farmers, it is an attractive market. There are over 100 varieties of mushroom that can be grown, and cultivated with manure, pulp, straw, wood or even waste.

He recently extended his lease on the spaces by more than a decade since business is flourishing.

“Oyster mushrooms also grow easily on cheap old chipboard panels,” said 68-year-old Mr. Rühl.

His crops are all grown organically. Even though it is more expensive, produce labeled organic makes a big difference to consumers, he said.

Mr. Rühl’s production facilities are in 16 big bunkers that once held the equipment of American soldiers. He recently extended his lease on the spaces by more than a decade, since business is flourishing.

Worldwide the mushroom industry generates revenues of more than $30 billion and is continuing to grow by 10 percent a year, according to market researcher MarketsandMarkets.

“By far the largest producers are the Chinese,” said Mr. Rühl. “We could learn a lot from their mushroom culture.”

Indeed, Asian farmers learned one thing from Europe: Mushrooms taste great even cultivated on livestock manure.

A truck pulls up, filled with white plastic bags of dark, moist compost containing spawn, which mushrooms grow from. These long strands are only a fraction of a millimeter thick and nearly invisible, but in the right conditions, they can flourish overnight into full-bodied harvest springing toward the light.

The white bags are slit open so the mushrooms can breathe. It’s hot in the bunker, as they digest the straw and emanate warmth. The mushrooms peep out of the bags, and with the perfect recipe of fresh air, 85 degree humidity and temperatures between 15 and 20 degrees Celsius, they can be picked about two weeks later.

“More moisture would make the mushrooms heavier but they wouldn’t taste as good,” Mr. Rühl said.

In the middle of the bunkers are wires hanging from ceilings almost to the ground. Wires carry sensors to measure the temperature, dampness and carbon dioxide content of the air. A computer tests optimal conditions for air conditioning and gentle humidification.

As a grower, Mr. Rühl’s biggest enemy is trichoderma, a common mold fungus in the ground that can destroy wood – and other fungi.

“That is why hygiene is important,” said Mr. Rühl, pointing to the whitewashed bunker walls. He also uses disinfectant:  “Hydrogen peroxide. That is permitted by eco-guidelines.”

Watering is also tricky. Too much water cannot touch the bags, but if amateur growers forget to sprinkle any, their harvests are miserable.

That is why Mr. Rühl is cultivating a special sort of oyster mushroom: “They are free of spores. They are more or less similar to seedless grapes.”

If only a fraction of such large-scale potential for growing mushrooms was used to produce food, experts say, there would be no more hunger in the world.

The main reason for his cultivation effort: Classic oyster mushrooms have copious white spores when they mature. They sometimes look as if they are covered in dust on a store shelf, and then customers don’t want them.

Mr. Rühl has recently developed a variety particularly rich in vitamin D: He calls them “light mushrooms” because vital additional ingredients enter with luminous help. Young researchers at the Universities of Freiburg and Hanover have found that many edible mushrooms naturally contain vitamin D and important B vitamins. If mushrooms are exposed to ultraviolet light, then vitamin D content increases considerably.

The process was developed by food biotechnologists at the University of Giessen, where Mr. Rühl’s son Martin is a researcher. Studies are being conducted there on how mushrooms create aromas and how they use waste, corn or rapeseed straw as a source of food or raw material. Scientists analyze complex cocktails, comprising hundreds of different enzymes that mushrooms spit out. The objective is to identify the most important enzymes and engineer them to help produce certain aromas or raw materials on a big scale.

“You can also produce a grapefruit aroma with mushrooms,” Mr. Rühl said.

An initiative by the Food and Agriculture Organization of the United Nations (FAO) is pursuing an entirely different course: In 2009, it called for more mushrooms to be grown in poor countries.

In a pamphlet “Make Money By Growing Mushrooms,” FAO makes suggestions about how poor people, women and those with disabilities in particular, could grow mushrooms using agricultural waste “without significant capital investment and access to land” and use mushrooms for nutrition and to improve their incomes.

Growing and cultivating mushrooms as a delicious food product and also a natural means of disposing waste has great potential: Almost the entire global biomass could be used to grow them. If only a fraction of such large-scale potential for growing mushrooms was used to produce food, experts say, there would be no more hunger in the world.

In the late 1960s, the leading British chemical enterprise at the time, Imperial Chemical Industries (ICI), was looking into simple, protein-rich mushrooms as an alternative to meat. After examining thousands of different kinds of mushrooms, ICI researchers found a way to produce myco-protein, or mushroom protein.

For years, authorities examined its suitability before it was officially recognized as a food. ICI has since been broken up and swallowed up by competitors. But a small British firm continued production of myco-protein.

Under the trade name of Quorn, business took off so well that the firm was acquired. More than three billion servings of the mushroom product, which is nearly neutral of taste and can be chewed without teeth, have already been sold as an alternative to mincemeat, sausage or thin slices of meat, mainly in Britain, Scandinavia, the United States and Switzerland.

The product is still in its infancy, but laboratories are competing worldwide to produce myco-proteins, from oyster or shiitake mushrooms in bioreactors free of the difficulties of harvesting real mushrooms. Sawdust, leaves or trash from the food industry are used to grow the mushroom protein. So far, none of the processes are economical – they have to be developed further and on a bigger scale.

There is also an automation process for conventional mushroom growing. Laser-guided, picture-recognizing robots learn how to pick mushrooms, which soon end up in growing facilities the size of stadiums, largely operated by remote control.

So much technology would probably scare off gourmands – which, in contrast, strengthens organic farmers and gatherers.


This article was originally published in Die Zeit, a sister publication of Handelsblatt. To contact the author:

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