Cantillon brewhouse
The public brew day starts significantly earlier than a typical museum visit, usually at 6:30 a.m., to accommodate the long brewing cycle required for spontaneous fermentation. My tour starts after 11 a.m. when the filtration is in process and the mash tun has been emptied. For a 10.000 liter brew the grain bill is made up of 850 kg barley and 450 kg unmalted wheat. What is left is a light brown-colored goo, thick and pasty.
Next, our tour guide Flosh takes us upstairs to see the two boiling kettles bubbling away. One kettle has spit out some of the hop, as if it didn’t like the taste of it. Cantillon uses massive amounts of hops, but they are aged for three years until they lose their bitterness. They aren’t used for flavor; they act as a natural preservative to keep “bad” bacteria at bay during the long aging process. Jean van Roy is there looking on, perhaps willing his stern look to keep the kettles in check. Most of the brewing equipment was purchased secondhand and is over 100 years old.
A small narrow staircase leads to the attic where the bags of malt are kept. If you look closely you can see light coming through holes in the roof in several places. Next to this large space there is a smaller room housing what for many is the highlight of the tour: Cantillon’s copper coolship. It can hold 7.500 liters and the cooling process takes around 16 to 18 hours. This explains why the roof is not insolated, though with heavy rain I wonder how they keep everything dry up there. Not visible from the inside are the 96 solar panels on the roof that produce all the electricity used in the brewery. According to their social media post three days prior, the nights were still a little warm for brewing. It needs to be cold enough for bacteria not to be active, but not too cold as to deactivate important yeasts. During our tour the coolship was empty, so I went back afterwards (with the brewer’s permission) to take a peek of it after filling. What a beautiful sight! It is a very large, shallow, rectangular vat made entirely of copper. The use of copper is traditional because it is an excellent conductor of heat, allowing the boiling wort to cool rapidly. The shallow depth is designed to maximize the surface area of the liquid. This is critical for the “spontaneous fermentation” process, as it allows the wort to be exposed to the wild yeasts and bacteria present in the Brussels air. The coolship is a primary reason why lambic brewing is seasonal. It is typically only used during the colder months (usually November to April) to ensure the wort cools to the correct temperature within a single night.
