While most commercial beers are brewed using carefully cultivated strains of yeast, Belgian Lambic beers ferment in large open vessels that are exposed to the atmosphere. Wild strains of naturally occurring yeast enter the vessels and inoculate the wort as it is cooled, setting off the fermentation process that yields the unique sensory profile of traditional Lambic beer. Ambient yeast is not used extensively, simply because it is difficult to maintain consistency between batches. The flavour profile is determined by several factors, including the type of yeast and bacteria in the air, the temperature of the brewing environment, aeration, and the length of time the beer is left to ferment. So, while spontaneous fermentation is ‘wild’ and unpredictable, brewers can carefully control many aspects of the process by choosing a specific location for production, brewing at certain times of the year, and using modern, highly technical equipment.
Author of ‘Wild Brews’, Jeff Sparrows notes that the character of spontaneously fermented beers arises from the environment of the brewery: “the air, the walls, the wood and the casks.” A blend of environmental conditions “determines the character” of Lambic beer. Lambic beer is aged for up to three years in large oak barrels called foeders, which let the ideal amount of oxygen in to allow the wild yeast to thrive. Each barrel has its own character and the wood affects the taste of the beer in its own special way. Distinctly tart with mild carbonation and a cloudy appearance, Lambic beer is ready to drink six months after bottling and can keep for up to twenty years.
Traditional Lambic is brewed in the Pjottenland region of Belgium, southwest of Brussels. In the twelfth century, the small town of Lembeek was known as a ‘free city’ because brewers and distillers did not have to pay tax. As a result, over forty breweries and distilleries were in operation by the nineteenth century. Situated on the banks of the River Senne in Lembeek, Boon Brewery has a rich history dating back to the late seventeenth century. The original owner, J. B. Claes purchased farmland at the site in 1680 and converted it to a brewery and distillery.
In 1860, the property was sold to Louis Paul, a passionate Lambic brewer who commissioned a malthouse at the site and bottled his first Geuze Lambic fifteen years later. The brewery was subdivided and sold over the next few decades until 1977 when Frank Boon bought it and began the legacy of Brouwerij Boon. An iconic figure in the brewing world, Boon modernised the brewery, eventually moving it to a new site at the centre of Lembeek. He entered a joint venture with Palm Brewery in 1990. Boon produced his first Lambic beer in the same year and since that time, Brouwerij Boon has been instrumental in restoring Lambic culture. Brouwerij Boon is no longer associated with Palm Brewery, but it is still owned and operated by Frank Boon and two of his four children, Karel and Jos.
Innovation and commitment to tradition have allowed Frank Boon to achieve consistency in the production of his Lambic blends which is reflected in the six consecutive gold medals they have won at the World Beer Cup. Because lambics must mature for up to three years in their foeders, Brouwerij Boon is reputed to hold the largest stock of Lambic in the world.
The Boon portfolio contains many varieties spontaneously fermented beer, including Oude Geuze Boon, a mixture of one hundred percent Lambic which is refermented in the bottle. The term Oude means ‘old’ and refers to traditional brewing methods Brouwerij Boon employs in his brewhouse that produce a more concentrated brew.
Kriek Boon is another popular blend of 100% Oude Lambic steeped in at least 250g of cherries per litre of beer and refermented afterwards. The cherries are harvested and handpicked in Poland; the staff at Brouwerij Boon are constantly searching for top quality produce. Fresh, bitter but slightly sweet with a cherry aroma, Kriek Boon pours deep red and is bottled using a champagne cork. It is unfiltered, contains no preservatives and has a 4% ABV which makes it the perfect, refreshing summer beer.
Frank Boon was raised with beer in his blood; his grandfather was a brewer and his mother was a food writer. He has strict regulations at the brewery – the equipment is cleaned with high pressure hot water and carefully polished. He is also responsible for the maintenance of the oak foeders which have been acquired over time from brewers and winemakers throughout Europe.
There are over one hundred foeders currently on site and each one holds up to 8,000 litres of Lambic. Boon commissioned a new brewhouse in 2013, with a capacity almost three times the size of the original building so the team can produce several different brews each day. While the brewhouse is fitted out with modern equipment, Boon still relies on authentic brewing methods. The original cooling facility, the koelschip, is still in use. It is a sizable, open vat situated next to large windows which are opened for ventilation so that natural microorganisms are carried through the air to stimulate fermentation. It is a complex process but Boon refuses to compromise on quality and his methods have proven to be a successful combination of authentic practices and new technology.
Keen for Brouwerij Boon to remain a family business, Boon encouraged his sons to become involved and Karel and Jos joined their father at the brewery in 2017. They grew up next to the brewery and Karel recalls summers spent cleaning and sorting bottles, weeding the garden, repainting the brewhouse and participating in beer festivals. In a recent interview with a US publication, Karel captured the reason he always wanted to join his father’s business, stating, “there’s so much know-how, the feeling, the philosophy that needs to be passed on that it is almost only possible through family generations.” Karel’s interests lie in sales and marketing while Jos is passionate about production and biochemistry.
As a family brewery, their focus is on crafting authentic Belgian beer and using raw, local ingredients to create delicate and complex flavours – the most important of which is arguably the wild strains of yeast from the Lembeek region.
The next exciting release from Brouwerij Boon will be their Boon Schaarbeeks, a fine blend of 400g wild cherries and Boon Lambic that has been aged in oak foeders. Schaarbeeks are a variety of tart, acidic cherries unique to the Lambic region and traditionally used in fruit Lambic. Frank Boon conducted tests with 28 different Schaarbeeks varieties in 2017 to find which one offered a high yield and produced the finest flavour. Boon Oude Schaarbeeks will be available for extremely limited release in the coming months.