I don’t like mushrooms. Oh, no. I hate them*. You will never see a beer and mushroom pairing on this site**. This distaste for fungus did not stop me from meeting with Le Champignon de Bruxelles – Brussels entrepreneurs cultivating mushrooms on the spent grains of Brasserie Cantillon, in the bowels of Anderlecht’s slaughterhouse.

Mushrooms at the slaughterhouse

The Anderlecht slaughterhouse (abattoir) occupies a large plot in the Cureghem neighbourhood, between the Brussels north-south rail line, the canal, the city’s inner ring road, and within spitting distance of the now-derelict industrial quarter. Twin monumental bronze bulls dominate the entrance. Meat, poultry and game shops cluster around the market complex, but this Monday evening its day traders and stallholders have long since gone. A wind whips through the wrought-iron slaughterhouse building built in the 1890s. Refrigeration units drip meltwater into empty corridors.

Le Champignon de Bruxelles (The Mushroom of Brussels) have set up their urban farm underneath this desolate plateau, occupying a wood-panelled nook amongst the asymmetrical vaults of the abattoir’s cellar. It is here that Sevan Holemans and his partners have revived the cultivation of mushrooms, a practice that died out here in the years after World War II.

Mushrooms growing in Cantillon's waste

These are not ordinary mushrooms, but exotic Japanese varieties Shiitake, Maitake, and Nameko. More exotically, these mushrooms are grown on the spent grains (draff) from a nearby brewery. Specifically, the draff comes from Brasserie Cantillon, 750m down the road.

Draff wasn’t always their first choice, however – in their first experiments they attempted to grow their shiitake mushrooms on coffee waste but it didn’t work out. They then moved on to experimenting with draff from then-new brewery En Stoemelings – both Le Champignon de Bruxelles and En Stoemelings have passed through the Ateliers de Tanneurs business incubator.

“For the moment we only produce the shitake on brewery waste,” says Sevan, and for the other two varieties they continue to use a more traditional wood substrate or nutrient base for the mushrooms. Their hope is that as production increases, the quantity and variety of mushrooms they grow on draff – substrate in the mushroom business – will increase.

With the explosion of brewing activity in Brussels in the last few years, you would think that getting your hands on more brewery waste in Brussels would be easy given the increasing number of breweries. Two issues complicate matters, however: “Our mushrooms are organic, we could only work with organic breweries.

"The only option in Brussels is Cantillon,” says Sevan. “The second problem, Cantillon, they only brew five months a year, they will start in November, and so it means that we have to work with other partners, otherwise we do not have enough.”

Where they source additional draff is out of their hands, and prospects of more breweries in Brussels being certified organic looks remote. “Some are speaking about it – en Stoemelings were thinking about it. Brussels Beer Project began making organic beer, but their hops come from the US, and when they get to Europe they are decertified,” says Sevan. With more organic breweries active in Wallonia, they source waste from breweries like Belgo Sapiens.

"Faking nature, year-round"

So how does it work? First, Le Champignon de Bruxelles process the draff from Cantillon in a machine that will clean and sterilise it, making it ready to act as the substrate. This phase – inoculation – is finished when the seeds are placed with the draff or wood substrate in a breathable plastic bag that will be home to the mushrooms for three months

Cultivation follows, as the mycelium – the vegetative part of the mushroom – grows in the substrate. Controlling the climate is crucial to the whole process. Each room requires carefully calibrated settings to reflect the season best suited to the different stages of growth the mushroom goes through. “You need to fake nature all year long,” says Sevan. In the cultivation room, “the mushrooms will stay around two months and half, and it is summer. The temperature is between 18-20°C. Humidity is super low, so here the mycelium will eat everything in the substrate – glucose from the brewery waste.”

Fruiting is the last step, when the mushrooms bloom into, well, mushrooms. This room smells different to the others, the mushrooms giving of a spicy, slightly meaty aroma that hangs in the air. They stay here – “in autumn” – for between five and 15 days before harvesting.

And the end product – is there any trace of beer or grain left behind in the mushrooms? Well, sort of. “We made the experiment, we tested and most of us, and most of the clients, tell me they won’t see the difference,” says Sevan. “But, some can taste and say ‘oh, this is this kind of substrate, and this kind. The taste of the mushroom, oh it’s a little bit more sugary.’”

A Brussels business

Sevan, and his friend and business partner Hadrien, came up with the idea for a mushroom-growing business in college. A third partner, the in-house agronomist, followed later. Economists by education, they were looking for an entrepreneurial opportunity in the circular economy. “When you speak about the circular economy, you often speak about mushrooms, because they are basically making the circular economy in nature,” says Sevan. They launched Le Champignon de Bruxelles in 2014, and bounced around locations in Brussels until finally arriving in Cureghem in December 2016.

Their move into the abattoir reflects a broader rejuvenation of the neighbourhood focused on the abattoir’s historic connection to the agri-food industry. A daily food market housed in a hulking concrete cube of a building adjacent to the main abattoir opened in 2015. A 4.000m2 urban farm on the roof of the market hall will follow.

The partners are from Brussels, and it was always their intention to start a business in the city. “We wanted to do something local. At first we only wanted to sell our mushrooms here, and did everything by bike,” says Sevan. This connection to Brussels is reflected in their name, branding, and in the Brussels dialect names they use for their mushrooms (Shieteke, Maaiteke, Nametje).

“We need to sell more”

As for the future, they are focused in increasing output. They currently produce around 1.2 tonnes of mushrooms. “We are trying to double this amount, but it is quite hard, because of the commercial prospects,” says Sevan. The business had planned to sell locally and stay out of the major supermarkets. A principled decision that was ultimately financially unsustainable, for a simple reason: “We need to sell more“.

To help them reach new customers and spread the word about their work, in September 2017 they launched an interactive experience for visitors to learn about mushroom cultivation. They are looking, again, to their draff supplier as a model – with a caveat: “In Cantillon they have 55,000 visitors a year. This is something that we will never reach.

"I mean, beer is something special.”

*I make no apologies for my 10cc appreciation. Good music is good music.

**Needless to say, we didn’t do a tasting of their mushrooms. And Sevan was yet to be persuaded by beers made with mushrooms: “I’ve tasted it in the past and I didn’t taste the shitake, it doesn’t taste of much.”