On a quiet side street in the Anderlecht municipality of Brussels is a storefront entrance to a living embodiment of brewing history – Brasserie Cantillon. When Cantillon opened its doors in 1900, it was one of more than a hundred operating breweries in Brussels. Today, it is one of a handful. Starting as a small family brewery, Cantillon is still family owned. Jean-Pierre Van Roy – a fourth-generation brewer – currently runs Cantillon.

What makes Cantillon so special is the fact that not much has changed since 1900. They brew and blend Lambic beers in the traditional style, which can take up to four years. This patience and attention to detail produces absolutely amazing products. The brewery is also very innovative and has pioneered a number of new and different variations on Lambic styles. Their brewing system is still in place from the first half of the 20th century. The brewery’s working “Gueuze Museum” is intended to preserve the traditional process of making Lambic beers.

Before we get into the process of making Lambics, let’s take a closer look at the beers themselves. Lambics actually share their family tree with wheat beers because they are approximately one-third wheat. What sets Lambics apart is their slow fermentation with wild yeasts and bacteria over one to three years. This gives them a wild funkiness and a lactic tartness that defines the character of sour-beers.

Straight Lambics can be young or old but are unblended and only lightly carbonated. Young straight Lambics have virtually no carbonation and are sold in pubs either plain or muddled with candi sugar, in which case they are called Faro. Cantillon’s signature straight Lambic is Grand Cru Bruocsella – a three-year-old straight Lambic. It can only be described as intense and extremely complex – a true aficionado’s beer and an acquired taste.

Gueuze is the most popular form of Lambic and accounts for half of Cantillon’s annual production. Gueuze emerged as a style following French monk Dom Perignon’s discovery of natural carbonation and the advent of glass bottles. It is a golden beer with layers of complexity, high carbonation (like a Champagne) and a long dry finish. Gueuze is a blend of one, two and three-year-old Lambics. Since no two casks of Lambic are ever alike, the master blender’s role is critical here in order to produce a reasonably consistent product from batch to batch. Cantillon’s blend of three Gueuze Lambics is: 50 percent one-year old Lambic, 33 percent two-year old Lambic, and 17 percent three-year old Lambic. Oude Gueuze is a blend of 100% Lambic beers with no additional types of beer, sugars or other ingredients in the blend. It represents a more authentic version of the Lambic tradition. After aging and blending, the beers are bottled and given an extra year of cellar time to allow a re-fermentation in the bottle. Rather than adding sugar to start the re-fermentation, Cantillon relies on residual sugars in the one-year old Lambic. Cantillon Gueuze, Gueuze Classic and Lou Pepe Gueuze are Cantillon’s main Gueuze products.

Authentic Fruit Lambics are also a part of Cantillon’s product line. More on them later on.

The Lambic Production Process

At Cantillon, the Lambic production process is long and radically different than most. First of all, because Cantillon is also the Gueuze Museum, it has retained most of the original early 20th century brewing equipment and brews on it to this day. Pumps driven by fly wheels and leather belts, chains, gears, a copper coolship and a range of other antique machinery contribute to what has to be one of the world’s most interesting brewing facilities. It really puts brewers to the test, both in terms of brewing on it and keeping it all working.

Lambics are brewed during the cooler months for a couple reasons. First, since the wort (unfermented beer) is cooled overnight in a shallow, open vessel, the night air must be cold enough to cool the wort. Second, the night air during the warmer months is actually “too wild” in terms of microflora, which can negatively affect fermentation and the flavor components of the beer. So, the brewing season for Lambics tends to run from October to April, although climate change will affect that.

The Mash

From Left: Grain Mill; Mash Vessel; Rakes in Mash Vessel; Sparging; Mechanical Pumps

The first step in any brewing process is the mash, during which starch from grains is converted to sugar by enzymatic activity. The grains (65 percent pale malt and 35 percent raw wheat) are first put through a grain mill where they are crushed to expose the starchy interiors of the grain kernels. The crushed grain is then added to the mash vessel along with hot water. The mash tun itself is a wood and metal vessel with a perforated false bottom (to separate sweet wort from spent grain) and rotating rakes to stir the mash, which is the consistency of thick porridge.

During the long and labor-intensive process of turbid mashing (traditional for Lambics) a step mash is used and some partially converted wort is pulled, heated to stop conversion and later mixed back into the main mash. This helps with the degradation of the raw wheat proteins and provides food for wild yeast and bacteria during the long (up to three years) fermentation. Because of the abundance of dextrins (non-fermentable sugars that can only be eaten by wild yeasts) in the wort, it has a very cloudy appearance – thus the name turbid. After the mashing process is complete, the grain bed is sparged (rinsed) with hotter-than-usual water (around 190º F, 88º C) in order to gelatinize starches from the raw wheat.

The Boil

From Left: Boil Kettle; Adding Aged Hops; Second Boil Kettle

After the sweet wort is drawn from the mash, it is pumped into one of Cantillon’s two kettles where it undergoes a long, slow (four-hour) boil. During the boil, aged hops (two to three years old) are added. The aged hops don’t add much bitterness or flavor but serve as a natural preservative for the beer, as their anti-microbial properties serve to regulate the level of lactic acid produced by lactobacillus and pediococcus bacteria in the wild fermentation. This allows the wild yeasts to become dominant early in the fermentation, which enhances their funky, earthy flavors.

The Coolship

The coolship (koelschip in Flemish) is an essential part of any spontaneous fermentation brewery like Cantillon. The coolship is an open, shallow vessel made of stainless steel or copper which served to cool the beer in the days before refrigeration. The coolship serves an additional purpose at Cantillon and other Lambic breweries; it serves to inoculate the wort with airborne microflora from within and outside the brewery – creating a spontaneous fermentation without other yeast additions.

At Cantillon, the coolship is located in the attic of the brewery, which has a special tiled roof that lets air in easily; it also has louvers at each end of the coolship room. After the long boil, the sweet wort is pumped up into the coolship. Depending on the weather, the wort may cool down overnight or it could take a bit longer. The weather needs to be cool enough to chill the wort, so Lambic breweries only brew from October through April. Once the wort is in the coolship, the louvers are opened up, allowing the night air to flow through and deposit wild yeasts and bacteria on the surface of the wort as it cools.

Once the wort is cool, it is drained into a vessel called a horny tank, where it is thoroughly mixed to incorporate the collected microflora throughout the batch of wort. The raw beer is then pumped into casks (predominantly red wine) where it will remain for one to three years. The casks have held lambic beer before and the wood is permeated with micro-organisms. Because a seasoned Lambic cask is so precious, Cantillon has coopers on staff who constantly clean, repair and re-build Cantillon’s casks.

Spontaneous Fermentation

Once the beer is in the casks, the true magic begins. The combination of wild yeasts and bacteria that settle into the coolship from the night air, and micro-organisms resident in the wooden casks, starts a spontaneous fermentation. In other words, no additional yeast is added, as would be the case with regular beers. Yeast foam overflows the bung of the cask, which hardens and protects the beer from the air until a pellicle forms further into the fermentation.

From Left: Barrel Cleaning; Fermenting Wort Flowing Out of Casks; The Pellicle; Long Aging in Casks

A pellicle is a nasty looking layer of biofilm – a colony of microbes that cluster together and float on the surface of the beer. Wild and sour bugs like Brettanomyces, Lactobacillus and Pediococcus result in the formation of the pellicle. It is believed by many that it helps protect the beer from oxidation and acetobacters that can give the beer a vinegary taste. Not all wild beers will form a pellicle, though, and it is not essential to the sour fermentation. Pellicles are also delicate and any movement of the cask can cause them to drop. That is why Cantillon’s casks are not disturbed during their one to three-year fermentation cycles. There is still a lot that is not known about pellicles and differing theories of why they form or don’t form.

Fermentation and Blending - Gueuze

As we discussed earlier, Cantillon’s finished products fall into several categories – Straight Lambics, Gueuze and Fruit Lambics. There can be significant differences between casks due to the numerous variables involved in Lambic barrel fermentation, so producing an absolutely consistent product is pretty much impossible. The role of the blender is to sample beers from various casks and determine the proportions of each to blend and achieve a “Cantillon” flavor profile.

From Left: Master taster; Barrel Aging; Bottle Conditioning

Blenders typically take samples from around twelve casks and narrow these down to five or six casks. After tasting several blends, they arrive at the final selection of beers for the beer they are making. Cantillon’s proportion of one, two and three-year old Lambics breaks down to 17 percent three-year old beer, 33 percent two-year old beer and 50 percent one-year old beer. This is a higher proportion of aged beers than many Lambic brewers use.

Fruit Lambics

Raspberries are Added Directly to the Cask

Cantillon’s fruit Lambics are made with a variety of fruits and typically are only made once a year. Fruits are added right into the aging casks, where they give up their fruit flavors and aromas after two to three months’ maceration in the beer. Cantillon uses a range of fruits in their various products, including cherries (Kriek), raspberries (Framboise – Rosé de Gambrinus), muscat grapes (Vigneronne), apricots (Fou’ Foune), elderflowers (Mamouche), rhubarb (Nath), 100% pale malt plus aged and fresh Hallertau hops (Iris), and merlot grapes (Saint Lamvinus). Cantillon fruit Lambics are all made in the traditional style, in which fruits are added directly to the casks and the sugars are allowed to ferment out.

At one point back in the eighties, traditional fruit Lambics were on the verge of dying out as sweeter styles of fruit Lambics (Lindemans, Timmermans, St. Louis, De Troch, etc.) became popular. These beers are blended with fruit juice concentrates and immediately pasteurized, so the sugars do not ferment out, resulting in an overly sweet beer that some describe as “cough syrupy.” These days they no longer present a threat to traditionally produced fruit lambics, which are internationally recognized as classics and enjoy high market demand.

Packaging and Bottle Conditioning

From Left: Bottling the Blended Beer; Bottle Conditioning; Wooden Crates

Once Cantillon’s beers are fermented, blended and/or fruited, they are put into stainless steel tanks and, in many cases, filtered before they are bottled. Cantillon’s filtration system is as antique as the rest of the brewery equipment. Filter pads are literally stamped out next to the filter array and the beer is then pumped through the filtration assembly on its way to bottling or kegging. This clears out fermentation sludge and fruit bits. The beer is then dosed with one-year old Lambic or a sugar solution, as well as fresh yeast, and bottled. Bottles of Gueuze then receive an additional year of bottle-aging and other beers get several months of aging in order to naturally carbonate in their bottles. Once bottled, Lambics can last for as long as 20 years or more if properly cellared. Cantillon uses Champagne-style bottles and inserts a wine cork into the bottle neck, locked in with a crown cap. Most Lambic producers use the more traditional Belgian cork and wire cage assembly.

Serving Cantillon Lambic

Drinking a bottle of fine Lambic at Cantillon is an experience. Their bottle bar features a good range of their current beers which must be consumed in the cozy tasting room. The bottles of beer are served in small wicker baskets, which allow the beer to be poured without disturbing the yeast sediment that forms on the underside interior of the bottle. Cantillon is particular about serving temperature. Surprisingly, Cantillon recommends serving their beers at between 54º and 59º F (12º - 15º C). Many would consider this warm for beer, but the higher temps allow a much more pronounced aroma and more complex flavor.

Cantillon’s traditions and processes go back 120 years. If you can’t go to Brussels and visit the brewery, definitely put it on your bucket list. As far as getting a taste of the world’s best Lambics, Cantillon beers are, to say the least, hard to find in American liquor stores. However, there are online sources that will ship beers directly to your home. They are pricey, but worth it!