For all the mystique that surrounds lambic beers, the process is the most natural and simple in brewing. The wort (beer before you add yeast) is brewed as normal, but then instead of pitching in a cultivated yeast strain, the liquid is poured into giant open-topped vats and exposed to the wild yeasts in the air. After 24 hours the liquid is poured into barrels and left to age for up to three years, where the wild yeast and bacteria in the barrels creates alcohol and sours the beer. That beer is called a lambic. To make a gueuze the brewer blends the old and new lambics to create a balance between sweet and sour, at which point some beers are then aged again over fruit to make various fruit lambic like Krieks, frambois and more adventurous ones. But spontaneous fermentation isn't the only way to create sour beers, in this section you'll also find so-called "kettle sours" where lactic acid or acidulated malt is added to the mash, as well as beers that have been infected with brettonomyces or soured slowly in a spirit barrel.
Sour beers have something of a legendary name in the beer world these days. This is partly due to their boundary-breaking flavours that are a far cry from the heavily hopped norm, but also thanks to their enigmatic, old-world character and designs.
For something seen as so complex, though, sour beers are the product of one of the simpler brewing processes. For pure lambic beers, brewers in Belgium’s Zenne valley take the pre-yeasted wort beer and pour it into a large vat with no cover. Then, for around a day, natural, wild yeasts in the air are allowed to enter the container and propagate, before the sour beer is aged for anywhere up to three years, with the wild yeasts forming the characteristic sourness and relatively high ABV.
Going further, gueuze beers are a blend of sourer two- to three-year-aged and sweeter one-year-aged lambic beers. Fruity sour beers can also be made by ageing lambics over cherry (known as kriek), raspberry (framboise), peach (pêche) and more.
And if you don’t fancy Belgian, so-called kettle sour beers are on hand – made in a mainstream brewing style with acidulated malts, brettanomyces, or lactic acid to create the classic sour taste.
Whether you’re new to sour beers or a seasoned lover of lambics, sour ales and sour IPAs, check out our selection below. Boon, Cantillon, Van Honsebruck – we’ve got a huge range from the best in the business. If you need any help with your order, get in touch, or for more information on beer topics view our features.