Flanders Beer Trail 2: No Boon of contention in classic lambic brewery

Frank Boon is a man of surprises. “I don’t make sour beer,” he says firmly. But doesn’t he brew lambic and gueuze, the famously sour Belgian beers?

“My beers are acidic, not sour,” he insists. “I brew in the winter and the beers are not sour.” He says he aims for less acidity than Champagne and reminds me that lambic is called “the Champagne of Brussels”.

I accept he doesn’t make sour beer. But then comes the next surprise as he leads the way into a modern brewhouse with all the familiar stainless-steel vessels – mash tun, lauter tun and kettle – you expect to find in a conventional brewery. Aren’t lambic breweries meant to be slightly decrepit, with creaking wooden vessels, cobwebs and spiders?

Frank says the original brewhouse failed to meet the demands of modern Health & Safety officers. The site is a former iron foundry and in 2011 Frank set about building a new facility that was finished two years later. It was opened by Herman Van Rompuy (pictured left, above, with Frank), a former Belgian prime minister, now President of the European Council and, most importantly, an old friend of Frank’s. In Belgium, given the importance of the brewing industry, politicians aren’t nervous of being filmed with beer in their hands.

Frank takes me from the new facility to a room under the eaves and points to the large open metal pan that covers the floor. It’s his koelschip or cool ship, what he calls “the signature of lambic brewing”. It’s here, when the pan is filled with hopped wort from the brewhouse, that the route to lambic begins.

Wild yeasts float in through the eaves of the roof and impregnate the liquid, attacking the sugars in the wort. Lambic brewers are grouped in the Senne Valley region of Belgium, with Brussels at its centre. Research at the University of Leuven has identified two main strains of Brettanomyces yeast that impact on the creation of lambic, labelled bruxellensis and lambicus, but in total there are some 35 yeasts involved in the production of this most idiosyncratic of beer styles, some of which create a film on top of the fermenting beer similar to the flor in sherry.

Once, all beer was made by spontaneous fermentation. It’s only in recent time that scientists, including Louis Pasteur, were able to unlock the mysteries of an organism known as “god is good” as a result of its magical ability to turn sugary liquids into alcohol. As soon as both commercial ale and lager brewers were able to use carefully cultured yeast strains, the days of lambic brewing were numbered.

They fell like dominoes in the 20^th century and it took a small band of dedicated brewers, including Frank Boon, to save and revive its fortunes. The Boon – pronounced Bone – brewery is in the town of Lembeek, which may be the source of the name lambic. There are many theories. Some suggest it stems from the period of Spanish rule when farmers brewed beer and also distilled genever or gin: the Spanish for distillery is alembic.

There’s been a lambic brewery in Lembeek since 1680. When the owner, René De Vits, decided to retire in 1977 he sold it to Frank Boon. Both were gueuze blenders: this means they didn’t brew beer but bought lambic from other brewers, matured it in oak vessels and then blended young and old beers to make gueuze. Gueuze – Frank prefers the spelling gueze – is the name given to a bottled and blended version of lambic. It’s the main type found in Belgium: straight lambic is rare.

Frank Boone’s new brewhouse has two mash tuns, two lauter or filtration vessels and one large boiling kettle. In accordance with the strict ordinances laid down by both Belgian and EU law for the production of lambic, Frank blends 60% malted barley with 40% unmalted wheat. He buys barley grown to his own specification and he calls the end result lambic malt. Pils malt, he says, has a fast level of protein degradation that doesn’t work well with wheat. Brewing water comes from a well on the site and is medium-hard.

He uses three times the amount of hops found in conventional beers, but they are aged hops, around three years old, and they have lost most of their bitterness. Frank and other lambic brewers are not looking for bitterness in their beers, and aged hops prevent infection and oxidation. Frank uses English Goldings and Styrian Goldings from Slovenia. A Muscat flavour in three year-old lambic comes from the hops, he says. Oxidised hops give a specific character to his beer, he adds, and “consistency is important”.