The Senne river winds its way from the Wallonian village of Naast through sleepy Flemish countryside until it reaches Brussels. Here it disappears beneath concrete, reemerging on the far northern outskirts of the city before joining the River Dyle close to Mechelen. It’s a small, short river that no one would write songs about except, that is, just southwest of Brussels something magical happens in the Senne Valley.
Wild yeasts proliferate along the course of the Senne, carried on the air these microflora become a critical ingredient in one of Belgium’s most legendary beers: lambic. The wonderfully named Brettanomyces Bruxellensis and Brettanomyces Lambicus are two of the most common wild yeasts that cause spontaneous fermentation when they find their way into wort, the sugary liquid that with the addition of yeast becomes beer.
The yeasts are unique to the Senne and the process of brewing is one of the most natural anywhere in the world. The wort is brewed as normal and the liquid poured into large open copper vats and simply exposed to the wild yeasts floating around in the air, typically overnight. After that, the magic happens au naturel. This process means that true lambics can’t be brewed anywhere else.
Once fermented, the beer is kept in wooden barrels for up to three years, an act that allows makers of lambic to claim they have more in common with wine than other types of beer. The result is a sour beer that really does divide opinion, at least in our household. That though is not the end of the story. Blending lambics and soaking them over fruit before a second fermentation creates gueuze.
There was a time when, out of favour with consumers, lambic was only kept alive by a few enthusiasts in small breweries. That has thankfully changed. Today a whole new generation of beer aficionados have discovered lambics, and the remaining breweries now cater to a growing domestic and international audience. Despite that, all lambic breweries are essentially artisan, using equipment that hasn’t changed in hundreds of years.
Luckily for me, the 50% of the household who likes lambic, not only is the Oud Beersel brewery accessible just south of Brussels, but the Cantillon brewery can be found in the city itself. I visited Cantillon a few months ago and took a self guided tour – it’s possible to go on a guided tour on a day when they are brewing – and had a three beer tasting afterwards.
It was interesting wandering around, discovering the ancient-looking copper vats and wooden barrels in a brewery that has been making these ancient brews since 1900. I tried their lambic, a gueuze, and a really delicious raspberry gueuze. The bar is also open to the public and was busy for a Friday afternoon. As was the brewery shop which was doing a brisk trade. I joined the queue and returned home with a few choice bottles.
A few weeks later, and purely in the spirit of scientific inquiry, I made my way to Brouwerij Oud Beersel close to the village of Beersel. Is it just coincidence that the word ‘beer’ is in the village name? The brewery sits in pleasant countryside about a kilometre away from the river amidst small orchards, which provide some of the fruit that goes into making several of their fruit gueuze.
Brouwerij Oud Beersel has been making lambic and gueuze almost uninterrupted since 1882. Almost, because in 2002 the brewery very nearly closed for good when the family succession ended. Luckily, a lambic enthusiast decided to take the business on and it reopened in 2005. Today, it offers guided tours and a tasing in their newly opened bierhuis.
On the tour we got the full story of lambic and the brewery and even got to meet the new owner, Gert, who was giving away saplings of the Schaerbeek cherry trees that go into making their kriek gueuze. The bierhuis does traditional Flemish food so I stayed and had lunch accompanied by a very tasty rhubarb gueuze. Needless to say, I returned home with a few bottles.