Scottish brewer BrewDog has launched Cosmic Crush, its first range of wild and sour beers, produced at the brewery’s standalone 'spontaneous fermentation' facility Overworks. The new range contains 10 beers, all matured in old wooden barrels.
‘The range can be split into two categories,’ Richard Kilcullen, brewmaster at BrewDog Overworks, told Imbibe. ‘The first category is [wild beer] fermented with our own cultivated brettanomyces, which works really well with hops.
‘The second category is beer made with a sour base, to which we add fruit. Fruit is really a big component for these brews.’
Indeed, BrewDog's new sours use a variety of fruits, combining them with other botanicals. For instance, Electric Blue, a new beer clocking in at 7.2%, marries blueberries and lavender, while Bedrock Red combines redcurrants and lemon verbena and sits at 6%.
Kilcullen explained that, for the sour beers, all berries are locally sourced and used whole. Tropical fruits such as mango, pineapple and papaya are pureed before they're added to the brew.
All the beers undergo fermentation in open stainless steel tanks, and are then moved into wooden barrels for a six-to-eight-month maturation. The fruit sours require an extra step: before maturation, the beers are moved to a different tank, where they're fermented for another week with the added ingredients.
According to Kilcullen, the sour beers take inspiration from the traditional lambics of the Pajottenland in Belgium. ‘One of the trends in craft beer is to look to the past for inspiration, another is to push the technical boundaries with modern techniques,’ Kilcullen pointed out. ‘I like to think that we sit in the middle.’
Several new releases are in the pipeline at Overworks. The brewery is planning to launch a series inspired by cocktails, which Kilcullen says will ‘use a lot of herbs, unique fruits, and push the boundaries'. BrewDog is also planning a series with beers matured in different types of spirits barrels.
The Cosmic Crush range of sour beers is currently available throughout all BrewDog bars and to the on-trade from the 16 February.