My earliest childhood memories are of shuffling through the corridors of Cantillon. This old building is my second home. Throughout my childhood, I worked here alongside my grandfathers, Marcel Cantillon and Pierre Van Roy. Today I am still here, working side by side with my present-day family—my parents, my sisters, and now the youngest of the bunch, my son Florian.
For a dozen or so years during my boyhood, I assumed that all beers were made by spontaneous fermentation, that they were all barrel-aged and then re-fermented naturally in the bottle afterward, just like ours. My relationship with lambic is thus much more emotional, more sensitive, than it is technical or even professional.
I am, I think, what you would call a brewer—or rather a blender—by instinct. It’s the reason describing my work as a brewer/blender at Cantillon in a technical way has always seemed more than a bit strange to me.
Lambic distinguishes itself from every other style of beer at every step of its production. The initial brewing itself is no different.
Awakenings, and the Turbid Mash
Our brewing season begins as soon as the nights are cooler, toward the end of October or the beginning of November. There’s always a great sense of impatience just before a new season kicks off. During the off-season in the warmer months, without the noise, the smells, and the particular atmosphere of a brew day in motion, something just seems to be lacking at Cantillon. As soon as temperatures cool and our old, 19th-century brewhouse groans to life—with its tanks filled, its belts and piston pumping into motion—it’s as if the whole building itself has come back to life.
We begin the mash-in by mixing about 1,200 liters (317 gallons) of hot water at 48°C (118°F) with 850 kilos of pilsner malt and 450 kilos of raw wheat. (That’s 1,874 pounds and 992 pounds, respectively; the grist is about 35 percent raw wheat.)
Once the temperature has risen to 56°C (133°F), we partially empty the mash tun for the first time, pumping 300 liters (79 gallons) of turbid wort into the first of two boiling kettles. Turbid wort isn’t filtered; it still contains traces of flour and grist.
By adding some boiling water to the mash tun, we raise the temperature to 66°C (151°F), and for a second time, we pump some turbid wort from the mash tun (this time about 1,500 liters/396 gallons) over to that first boiling kettle. Now, we heat this 1,800 or so liters of turbid wort to a simmer, to just about 90°C (194°F). We do this in order to preserve complex sugars, like dextrins, in the wort. These complex sugars will bring a certain roundness to the beer and foster a long life, providing nourishment to the Brettanomyces, which are capable of metabolizing them.
As the turbid wort heats in the boiling kettle, we’ll add more boiling water to the mash tun to bring the remaining mixture to 72°C (162°F). We then stop the tun’s mixing blade and empty its contents for a third time. We pump this wort—much clearer and brighter now—into the second boiling kettle.
To reach the last step at 78°C (172°F), we pump the 1,800 liters simmering in the first boiling kettle back over to the grains into the mash tun. We follow this sparging the mash with 85°C (185°F).
We end up with 9,500 to 10,000 liters of wort in total (about 2,600 gallons, or 84 barrels) between the two kettles. Then it’s finally time to start the boil.
The Boil, and the Coolship
Before the boil, we add 25 kilos (55 pounds) of aged hops to the wort, divided proportionally between the two kettles. We use only Noble hops whose alpha acids are low to begin with and diminish further while aging for two or three years. These oxidized hops still bring a little bitterness to our beer, but more importantly, they have a very important role to play as a preservative and bacteriostatic agent during the fermentation and aging processes.
Three to four hours of boiling is necessary to reduce the wort by 25 percent of its starting volume, as well as boil off any of the cheesy aromas that may be lingering from the aged hops.
By the end of the afternoon, we pump about 7,500 liters (a bit less than 2,000 gallons) of wort into the coolship in the attic. It will stay there one night, during which dozens of different yeasts and bacteria will inoculate it. The coolship’s size and depth are designed to optimize cooling and inoculation. It’s very wide across but quite shallow, allowing for maximum exposure of the wort’s surface to the air.
The next morning, the now-inoculated wort should have cooled to about 18° to 20°C (64° to 68°F) and have a density of 12.5°P (1.050). Such a rapid cooling of the wort is only possible during cold nights—ideally near freezing—or up to a maximum of 8°C (46°F), which is why our season spans from the end of October to the end of March.
Once the wort is cooled the next morning, we pump it into barrels. The spontaneous fermentation begins shortly afterwards.
The External Threat
It’s hard to say exactly how “shortly afterwards” the fermentation begins because in recent years the fermentations have tended to start later and later, and they progress much more slowly. Here, I will make a small digression from our discussion of process to address a possible new threat to our tradition.
Could this slowing down of the fermentation be a consequence of climate change?
Brewing lambic in winter permits us to work in a “cleaner” environment, so to speak, thanks to a reduced population of bacteria and insects in the colder months. The reduction in atmospheric bacteria helps to promote a more active population of wild yeasts.
So, could these winters—getting warmer each year—be responsible for the slower fermentations that we’re seeing?
A great many natural winemakers in the north of France have witnessed the same evolution of their fermentations. One hypothesis they’ve floated is that an increase in bacterial activity during these more clement winters is responsible for slowing the wild yeast–driven fermentation.
These slower fermentations aren’t currently a serious problem, though they threaten to become so if this phenomenon were to continue in this same direction.
The Art of Assembling the Puzzle Pieces
But let’s put that worry aside for now and come back to our lambic, which goes on to age from one to four years in the barrel. We never top up these barrels, so the beer protects itself from the air within by forming a pellicle (veil of yeast).
Each batch of lambic produces a uniquely different beer, but after two years, each barrel itself has become unique. This is where the tricky but indispensable work of blending comes in to play—the puzzle of tasting and blending varying flavors and aromas to create balance from chaos.
We produce only about 2,500 hectoliters (2,130 beer barrels) of lambic per year. By the end of the brewing season, when our capacity is full, we have roughly 1,600 casks—of 400 to 500 liters each—at our disposal.
Obviously, it would be impossible to taste them all at the same time. That wouldn’t be logical anyway, since within a few weeks’ time the beers could continue to evolve—sometimes even radically so.
So, when we start a blend, we taste barrels at random to select the area where we’ll concentrate our work for the blend. This is also a practical matter: Once we start with a line of barrels, the goal is to empty them all, so that we can make more space for the next brew.
Each beer necessitates a particular type of lambic. We macerate more delicate fruits with beers that are rounder, without any extremes. On the other hand, we can pair hardier fruits with stronger, more complex lambics with a more pronounced character.
The most emblematic blend of the brewery is, of course, that of Cantillon Gueuze. In it, we find all the different types of lambic present in the brewery, from the oldest to the youngest, from the mellowest to the most harshly acidic. We need a dozen or so barrels to blend one batch of gueuze. While no batch is ever identical to another, it should in any case allow an enthusiast to identify the signature characteristics of beers from our brewery.
The Zen of Brewing Lambic
Even with all of our experience, the results are never guaranteed—that would be too easy. This is one of the reasons I love working with lambic, a beer that has its own natural cycle, unique to itself, without any intervention from the brewer.
This is also why, in my opinion, the title of “master brewer” isn’t really applicable to lambic. To deserve such a title, you have to know how and be able to control your product at every step—which is simply impossible with a beer that’s spontaneously fermented. I consider this beer to be a partner in my work; it’s certainly not a malleable material that I can manipulate as I wish to give me the same exact result, every single time.
Lambic is a living beer. Our visitors often tell us that there’s a soul to our old brewery. I dare to believe that this soulfulness unique to lambic will last for many more years to come.
Toward Lambic’s Future, in the Context of the Past
However, this centuries-old beer nearly met its end after its last years of glory in the 1950s and 1960s. At the end of the ’60s, industrial lambics—made in only a few weeks, pasteurized, and sweetened—arrived on the scene. Their sugary sweetness proved to be much more profitable and well suited to the consumer tastes of the time. They would have rapidly displaced traditional lambic beers, driving them nearly to extinction in less than 20 years.
In 1945, at the end of World War II, Brussels counted well over 30 breweries and blenderies within her borders. By the beginning of the 1990s, only Cantillon was left. It was a veritable slaughter.
If lambic is still alive today, it’s certainly thanks to a handful of people who fought through thick and thin to preserve a centuries-old tradition. In that tiny group, I can proudly count my parents, Claude and Jean-Pierre, as members. Without that group, real, Brussels-born lambic would have ceased to exist.
Over the past 20 years, our beer has known a new golden age, but we should never forget the immense majority of beers still sold in Belgium today under the name “Gueuze Lambic” or “Kriek Lambic.” Those are exactly the same beers that threatened to make traditional lambic disappear so many years ago.
For that reason, I watch with anticipation as a new class of spontaneously fermented beers arrive on the market. I believe that they have something to contribute to the renowned tradition of true lambic.
When my fellow brewers in North America or elsewhere in Europe work with quality raw materials, respect the time, the ingenuity, and the dedication necessary for their product, the results are often excellent. I am delighted by the continuing success of these new wild beers throughout the entire world. Lambic continues to be a source of inspiration for these brewers, and they inspire me as well. They are a driving force, constantly pushing me to innovate.
People often ask me for technical advice about making lambic. It’s hard for me to answer these questions because I work from such an emotional, instinctive place.
So, my advice is very simple: To make beers of quality, rigorous work and a close eye on their evolution are absolutely necessary, of course—but in the end, the most important thing is to remain humble in the face of nature and, above all, to carry out your work with care and passion.