The Afterlife of Viennese Coffee

A row of oyster mushrooms in the indoor growing facility at Hut&Stiel

A row of oyster mushrooms in the indoor growing facility at Hut&Stiel

There is nothing unusual about Manuel Bornbaum and Florian Hoffman's love for coffee. After all, they live in Vienna which may well be the coffee capital of the world—Viennese coffee house culture is on UNESCO's list of intangible cultural heritage and many of Vienna’s coffee houses date back to the 18th century. But Bornbaum and Hoffman aren't looking for a rich espresso or a creamy cappuccino. They are on the hunt for used coffee grounds in the order of about a ton of grounds a week. Bornbaum and Hoffman are not waste collectors or coffee refuse connoisseurs, they are Vienna’s only commercial oyster mushroom growers. These two childhood friends from Northern Austria both attended university in Vienna where Florian studied mechanical engineering and Manuel studied agriculture. After brief stints in other professions they became fascinated with urban mushroom farming and started their company, Hut & Stiel. But the most unique part of the business is that for the substrate in which to grow the mushrooms they use coffee grounds, a common by-product of European cities—and especially Austria. Manuel says that besides the prominence of coffee, Vienna is the perfect place for this kind of venture because of the large vegan and vegetarian movements and the city’s focus on regional and sustainable food. 

Manuel showed me around Hut & Stiel’s underground facilities and walked me through the mushroom growing process from spore to salad. The first step in the process is to take a mushroom spawn—a substance that has been inculcated with mycelium, the vegetative part of a fungus—and mix it with the coffee which serves as a substrate for the mushroom (or the material from which the mushrooms will grow). Bornbaum and Hoffman chose to grow oyster mushrooms because of the convenience they afford. Normally, when growing mushrooms, the substrate has to be sterilized to ensure it is free of bacteria and other molds. But oyster mushrooms grow faster than almost every other type of mushroom, so they can be cultivated without the complicated process of sterilization.

The mycelium coffee mixture is kept in one room for 3 to 4 weeks so the mycelium can grow through the coffee and then the bags are moved to another room where they start to produce fruiting bodies otherwise known as mushrooms. Holes are torn in the bags so the mushrooms can grow through and then the mushrooms are harvested. Two weeks later each bag is harvested a second time and then two weeks later a third time. In total each bag produces between one and two kilos of mushrooms. Mushrooms require cool and humid growing conditions so reliable air conditioning in the summer is essential.

Hut & Stiel also has a lab where they are experimenting with different mixtures for growing their own spores which are used to start the fungal culture. This is essentially done by taking the spores, which are extracted from mushroom caps, and mixing them with coffee grounds and grains like millet. Right now Hut & Stiel doesn’t use its own spores for the mushrooms they sell because it is a very sensitive process and they haven’t yet developed a method where they can ensure the quality of the spores. Low quality spores mean no mushrooms and no mushrooms mean no business.

Everything about Hut & Stiel is hyper local. Every coffee pickup and mushroom delivery has to be accessible by the company’s electric bike and so the farthest delivery point is 7 or 8 kilometers. Besides old age homes, Hut & Stiel also collects coffee grounds from the restaurants it delivers mushrooms to as well as other bakeries and coffee shops. When most people consider the prospects for urban agriculture the first thing that usually comes to mind are the obstacles that arise as a result of their small scale, but other activities such as collecting coffee grounds from numerous urban institutions to use as a medium for mushrooms are unique to urban farms and would not be possible for a large scale farm.

Although Hut and Stiel has no problem selling its product now, Manuel says it was initially challenging to market the mushrooms because as a small new business chefs didn’t take them seriously. Also, mushrooms are not very prominent in Viennese cuisine and oyster mushrooms in particular were not popular because they have a short shelf life and are hard to transport. But with Hut & Stiel’s model, the time between harvest and delivery is usually only two to three hours and so the freshness is a major selling point. Media publicity also didn’t hurt. The business first attracted the attention of a radio show and then the biggest newspaper in Austria. Once the media exposure picked up they had absolutely no problem marketing their mushrooms, and TV interviews, additional articles, and documentaries quickly followed.

In fact, in the short two years they have been in business, Hut & Stiel’s product has been in such high demand that this is the first time they have more mushrooms than they have sold. This has given them the opportunity to produce value added products, such as pestos and spreads, which they sell at markets and grocery stores. They are also experimenting with mushroom based vegan sausages which Manuel says are turning out to be delicious. Hut and Stiel also runs tours that include tastings of the products at the end, as well as full day workshops once a month on home mushroom growing. The transformed mushroom products and the tours have been so successful that Bornbaum and Hoffman are currently forming a second company. According to Austrian law, farms have to make 75% of their revenue from the produce and 25% can be from other sources such as classes or processed produce. Since these additional parts of the business are growing rapidly, Bornbaum and Hoffman have to start a new company to manage it.

I was curious what it was about Hut & Stiel’s model that makes it so successful. According to Manuel it is because mushrooms aren’t polarizing like some other urban agriculture ventures such as aquaculture or insect farming. Oyster mushrooms in particular are actually called the veal mushroom because of their meaty taste, and so they can really be marketed as a meat alternative. He also thinks the concept is attractive to many different communities such as the vegan and vegetarian movements and even people in the biking movement. They also utilized an unused basement which was too wet to use for storage so they are not using extra land. But there is still room for growth for these kind of enterprises and Manuel hopes to increase the demand for mushrooms by showing how sustainably they can be produced and how delicious they taste.

Even though he spends most of his day working with them, Manuel has not yet gotten sick of mushrooms. His preferred way of eating them is roasted over a salad or pasta. But his favorite part of the job is meeting all different kinds of people. For Manuel this is the crux of urban agriculture. In Austria, urban agriculture is not needed to ensure an adequate food supply as the country has plenty of land for farming. But the power urban agriculture has to bring people together makes it an essential component of the urban landscape.