Cantillon says it with flowers

It’s a nondescript street in the Anderlecht district of Brussels but push open the heavy wooden door of 56 Rue Gheude and you enter one of the most remarkable breweries in the world. This is the home of Cantillon, an uncompromising producer of classic lambic and gueuze beers, made by spontaneous fermentation, using wild yeasts in the atmosphere.

The brewery has changed in recent years, in step with a new generation of the Van Roy family taking charge. Since 1978, Cantillon was run with enormous passion and flair by Jean-Pierre Van Roy. He married into the founding Cantillon family, who opened the brewery in 1900. Jean-Pierre retired in 2003 and handed control to his son Jean, though the father is still much in evidence, advising on brewing and helping with tours of the site. Cantillon is now officially called the Museum of Gueuze and visitors are welcome at any time during opening hours. For a small sum, they can tour the brewery and sample the end products, which are made solely from organic ingredients.

Lambic is the oldest type of beer in existence. It dates back 400 years but may be much older. It can legally be brewed only in Payottenland, the area centred on Brussels and the surrounding Senne Valley. In spite of the presence of a vast modern city such as Brussels, the origins of lambic are rustic and bucolic. It was a beer brewed by farmers and peasants, using raw materials from the surrounding fields and allowing nature to turn a mash of barley malt, wheat and hops into alcohol. The drink consumed by peasants in the paintings of Breughel the Elder is lambic, not wine. The style has been protected by Belgian law since 1965 and by the European Union since 1992: they enjoy the equivalent of a French appellation contrôlée for wine.

Lambic is best known to the world outside Belgium in the versions called kriek and framboise: kriek is Flemish for cherry while framboise in French or frambozen in Flemish stands for raspberry. The fruits encourage a further fermentation and add delightful additional flavours to the beer. But at Cantillon, first Jean-Pierre and now Jean Van Roy have pushed the boundaries of lambic further by using other fruits, such as apricots and grapes, and have now added elderflowers to their beer.

Visitors start the tour on the ground floor where they see small mashing and boiling vessels that produce the ‘hopped wort’ ready for fermentation. The process begins in a mash tun where malted barley and unmalted wheat are thoroughly mixed with pure hot water. Lambic is a type of wheat beer and its protective laws lay down that at least 30% of the mash must be made up of wheat. During the mashing process, starch in the grain is turned into fermentable sugar. The sugary extract or wort is then pumped to a copper where it’s boiled with hops.

The copper boil is enormously long. It lasts for up to four or five hours, three or four times longer than a conventional brewery boil. And the hops that are used are several years old and have a cheesy aroma, as they have lost their natural aromatics. Lambic brewers don’t want a strong hop character in their beer as bitterness does not marry well with the aromas and flavours created by wheat, wild yeast and storage in oak. Hops are used primarily as a preservative and the cheesy character will disappear during fermentation and ageing.

Brewing practice ends at this point and nature takes over. Visitors to Cantillon are taken to the brewery attic where, during the cool months between October and April – lambic brewing doesn’t take place in the summer when temperatures are too high – natural fermentation begins. The hopped wort is run into a large, shallow open pan known as the cool ship. Louvred windows are left open and slates are removed from the roof to encourage wild yeast spores in the air to enter and attack the sugars in the liquid. The yeasts used in lambic brewing are known collectively as Brettanomyces and scientists at the University of Leuven’s brewing faculty estimate that in total 35 different strains are used to create lambic: they are made up of spores from the atmosphere, further strains in the brewery cellars and yet more locked in the wood of the casks used for ageing.

Once fermentation is under way, the liquid is transferred to the cellars, where it’s aged in oak and chestnut casks bought from the wine industries in France, Portugal and Spain. The wine flavours trapped in the wood add their own distinctive character to the beer while micro-flora in the casks joins the wild spores from the attic and continue fermentation.

Lambic ages in cask for at least a year, sometimes as long as six. Lambic served straight and usually on draught is flat, sour, tart and almost cider-like. Gueuze, a bottle-conditioned version, is a blend of old and young lambics, usually at a ratio of 60% young to 40% old. The beer is aged for between six to 18 months in the cellars in bottles with corks and wire cradles. When the cork is released, the beer foams and gushes like champagne – it’s thought the name gueuze comes from geyser. Gueuze is sharp, tangy, sour and wonderfully quenching.

The regular Cantillon beers are Grand Cru bottled lambic, Fou’Foune, made with the addition of apricots, Gueuze, Kriek, Lambic, Rosé de Gambrinus (framboise with a small amount of kriek), and Vigneronne, bottled lambic in which Muscat grapes have been steeped. The last-named in 6% alcohol, all the others are 5%.

Jean Van Roy brought a bottle in an elegant wicker basket to our table and poured glasses of Mamouche. This is 5% lambic made with the addition of fresh elderflowers. It has a bronze colour and an earthy, floral, herbal and sour aroma. It’s stunningly sour in the mouth with notes of elderflower, yeast and a faint hint of hops. The long finish is sour, dry and fruity, with a powerful note of elderflower and a salty, iodine-like note.

The second beer we tasted, Iris (6%), has been in production for several years and I was keen to sample it again as it marks a departure from the main Cantillon range. It’s not labelled lambic as it’s an all-malt beer, with a 50-50 blend of aged hops and fresh Saaz. The beer is aged in cask for two years and then a further addition of fresh Saaz, inside a linen bag, is steeped in the beer. A house yeast culture is used. The finished beer has a red-gold colour and an intensely sour nose balanced by juicy malt and spicy hops. The palate and finish are sour, tart, tangy but with a fine balance of biscuit malt and floral hops.

Jean then unveiled Zwanze Zoll, a 8% beer aged for two years, a blend of lambic and Pineau d’Aunis wine. The beer is the result of collaboration between Jean and the French wine maker Olivier Lemasson, who uses only organic grapes from the Loire Valley. The result is a wine with a spicy and peppery note that marries well with the musty and sour nature of lambic. The beer has a bright ruby colour, a pronounced grape note on the nose balanced by lambic sourness, followed by a sour palate with tart and spicy fruit, and an intensely dry, tart finish with a late burst of grapes.

Jean beckoned me down to the cellar where he tapped a wooden cask and gave me a sample of a lambic ageing in cognac barriques. The beer is not yet ready for release but already it’s an amazing blend of sour beer with the rich flavours of distilled grape and a warming kick of alcohol. I suspect the finished drink will be sensational. But that would be only keeping with all the Cantillon beers that underscore the mystery, the magic and the history of the world’s oldest form of brewing.

*Cantillon and the Museum of Gueuze, 56 Rue Gheude, 1070 Brussels. Tours and a beer sample cost six euro per person. Group bookings are available. See website www.cantillon.be. Open 9-5 Monday to Friday; 10-5 Saturday. Closed Sunday and public holidays. The brewery is five minutes’ walk from Brussels Midi, the Eurostar terminus: see map on the brewery website.