Miracle of Zenne Valley...

casks at Drei Fonteinen brewery
Brettanomyces: The name of the little creature who is responsible of the miracle happening in the valley of the RiverZenne (Senne) over and over every year... It sneaks into the attics of the breweries under the tiled roofs finding its way to the cooling ships filled with a cooked mix of grain to start the unique and marvelous spontaneous fermentation of Lambic beer. For centuries fermentation was believed to be a miracle by itself, God’s reward for his faithful believers. Even the German Purity Law of 1516 didn’t mention yeast as one of the ingredients in beer. Along with the rest of the world, the brewers in the Zenne Valley didn’t have a clue how fermentation started. It was just happening…

Lambic and Geuze beers have been always one of my favorite brews. Not only because of their sour, layered and complex taste, but also because of how their taste profiles change drastically within miles in the valley, with different types of casks used and with different length of maturation.

cellars at Oud Beersel brewery
Although the historic records list that the traditional grain ratio of Lambic beer is supposed to be 6/16 wheat and 10/16 barley, nowadays most brewers use a ratio of 40/60. After the wort (grain mixed with water) is cooked for almost four hours, which is way longer than in normal brewing processes, it is allowed to cool down in stainless steel cooling ships to allow the yeast to do its job. Because of the nature of open air cooling, the brewing season is limited from Fall to Spring. Temperatures more than 18C-20C (65F-68F) result in acidity in taste and, more importantly, can cause infections. The fun part starts after the barrels are filled with the cooled wort. Wild yeast starts to work immediately and can be witnessed by observing the overflow of white foam around the bung at the top of the barrel. At that level bungs are not tightly sealed to allow the foam to flow out to protect the barrel and allow more oxygen in and carbon dioxide out. It settles down in about two weeks and the barrels are sealed. The brew continues to ferment in the casks for up to ten months, going through different fermenting phases that are all closely monitored. After that, the beer is ready to be consumed as Lambic or to be blended as Geuze.

Blending Geuze is a relatively new process. It all started with bottled beer taking over the world at the very end of the 19th century. Beer in bottles was easy to transport and reached consumers who couldn’t afford to buy bulk beer in casks. On top of everything, imported bottled German beer was less sour and had a good head. To be able to survive in this new market, some Lambic brewers started to bottle their beers using the Champagne method. They basically bottled older Lambic beers with much younger ones still containing sugar to allow a secondary fermentation in the bottle. The result was sweeter and had a great head: a new type of beer was born. Like in the whisky industry, the beer world suddenly discovered the art of blending.

After WWII, a new type of blending started by mixing, actually, non-Lambic beer and pure carbon dioxide with blends of Lambic beers to make them even sweeter and with more head. A distinction had to be made between these two different blending methods to protect the authenticity: Traditional Geuze started to be labeled as “Old Geuze” and the new less pure method kept the term “Geuze”.
Leuven Town Hall
The best way to learn and enjoy more Lambic/Geuze brews is to take a trip to the valley of River Zenne. We made our pilgrimage last August. It was a five day trip and we chose the city of Leuven as our base. Leuven is a pretty Flemish city east of Brussels. It is an old college town, famous for its sidewalk cafes, serious cycling culture, and as the home of Stella Artois brewery. Our first visit was to Oud Beersel brewery. Oud Beersel was founded in 1882 on the outskirts of the little town Beersel but mothballed in 2002. Fortunately it was saved by two young beer enthusiasts,  Gert Christiaens and Roland De Bus, who simply didn't want to see their favorite beer gone forever. The brewery re-opened in 2005 and in 2007 when Roland had to leave due to family reasons, Gert decided to continue all by himself. The tour was good and the tasting follower was very casual and informative. Their Oude Geuze is a wonder, by the way.

tasting at Oud Beersel brewery

Second stop was Drie Fonteinen brewery, which has been owned by the same family since 1953. We were very lucky to meet the master brewer Armand Debelder and his wife. Armand gave us the long tour, told us the history of the brewery and explained every single step of the process at an amazing level of detail. I have to say I learned more about Lambic and Geuze there in two hours than anywhere else. It is always inspiring to see somebody so passionate about what he does. And Drei Fonteinen Oud Geuze is one of the best beers I ever tasted.
Armand Debelder is pouring samples directly from the cask
De Fiere Margriet
A big chunk of the rest of our time in Leuven was spent at De Fiere Margriet (located right behind St. Peter’s Church) which is definitely one of the best beer bars in Belgium, along with Kulminator in Antwerp and Chez Moeder Lambic in Brussels. Their inventory is endless and they are open very early in the morning. So, needless to say, many mornings our day started right there. To be honest, that joint might be easily a reason by itself to visit Leuven.

If anybody wants to learn more about Lambic and Geuze beers “Geuze & Kriek” by Jef Van den Steen is an excellent book that inspired and encouraged me to plan my trip to Leuven almost a year ago.

[edited by Teresa Hartmann]

[special thanks to our friend Pieter Bruelemans for pointing us to the direction of Leuven]

*Originally written for and posted at The Alcohol Professor on January 7th, 2014.