You can work out how old your bottle of Boon Oude Geuze is thanks to the label affixed around its neck – it’s usually released three years after this date, which denotes the beer’s brewing season.
Around this time each year, when the temperature drops low enough, the lambic brewing season begins in Belgium’s Zenne Valley region, at the southwestern tip of Brussels. From then it will continue until temperatures once again rise above unacceptable levels for lambic brewing the following spring.
Brussels and the Zenne Valley are famous in the brewing world for the microflora the environment is home to. It harbours myriad strains of wild yeast perfect for spontaneous fermentation such as Brettanomyces Bruxellensis. The wort that lambic producers create is allowed to cool overnight in a long, shallow metal vessel known as a “koelschip”,
or “coolship” in English. As the wort cools, it’s inoculated by wild yeast before being transferred to oak barrels for fermentation.
Lambic attains its sourness not from the process of spontaneous fermentation, however. Brettanomyces gives lambic brewers the long and slow fermentation they desire, but the sourness will occur post-fermentation, taking place over a period of up to three years within its oak barrel. Moist, wort-filled barrels make an ideal home for bacteria such as Lactobacillus and Pediococcus, which often makes certain barrels or large oak vats known as foeders particularly prized by brewers. The heat of the summer months gives rise to all manner of undesirable bacteria however, which is why the lambic brewing season only extends from autumn to spring.
Lambic is becomingly increasingly sought after, especially brands such as Cantillon and 3 Fonteinen. This is with good reason too, as their products are superb. However I still delight in the fact that I can always pick up a bottle of Boon Oude Geuze with very little effort. The fact that it’s less hyped and produced in relatively larger quantities means that I don’t have to worry about this changing any time soon, either.
This year’s vintage reminded me of why I appreciate Boon’s lambic and geuze so much. It’s bright and complex – but not to the point of being hard to understand. Flavours of lemon juice and green apple are ever present from the point it pops in your mouth to the moment it zips down your throat.
By all means chase after the rarest and most sought after lambics you can possibly find. I’ll be here in the meantime, sipping at a Boon and not worrying too much about what should and shouldn’t be fussed over.