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22nd July 2019

New yeast sours and ferments without need for bacteria

Following on from their cutting edge work with the unique Norwegian Kviek yeast in 2018, Yeastie Boys have once again lived up to their name – and innovative heritage – by being the first UK brewery to use a recently discovered yeast that produces sour beers without the need for lactic-acid producing bacteria.

The sour ale Heaven Up, a Lemonade-inspired Berliner Weisse released last week, utilises a new strain of yeast that is the result of many months of bio-prospecting, laboratory work, and test batches of around 300 possible yeast strains in America.

Yeastie Boys Creative Director, Stu McKinlay, explains: “I picked up on whispers of this amazing yeast, last year, and our head brewer JK was immediately fascinated with the idea of using a brewer’s yeast that removed the traditional need for bacteria to produce a sour ale. It took a lot of asking around, a little dumpster diving, and over a year of elapsed time between our first chat and getting Heaven Up into kegs and cans.”

“Introducing bacteria to a brewery not only comes with risks but adds fairly significant changes to the brewing and/or fermentation processes” Head Brewer James Kemp added. “This new yeast enables brewers to use standard processes, and gain the complexities of traditional sour fermentation, while lowering usual risks associated with creating sour beer. We expect to see a lot of UK breweries using this yeast in the years ahead.”

In traditional sour beers the sourness is produced by lactic acid producing bacteria – in the mash, kettle, or during fermentation – with the alcohol produced by saccharomyces yeast. The yeast strain used in this beer does both, first reducing the pH and creating the trademark sourness of Berliner Weisse, before producing alcohol via fermentation.

Heaven Up – a bright summery ale inspired by sour lemonade – is dosed with the peel of lemon and lime, as well as black and white limoo amani (dried limes), to add a vibrant citrus complexity alongside the sour fermentation. Heaven Upis a living beer that will continue to develop complexity over time. At a modest 3.8% Alc/Vol, and with a crisp and refreshing acidity, it’s an excellent beer for the parks, barbecues, and train journeys this summer.

The beer is available to trade customers now, direct from Yeastie Boys and through craft beer wholesale partners such as Biercraft, Jolly Good Beer, A New Wave, Glassworks and New Zealand Beer Collective.


About Yeastie Boys:
Yeastie Boys is the world’s smallest multinational – founded in New Zealand and now also brewing in Australia and United Kingdom (all without their own brewery).
The brainchild of Stu McKinlay and Sam Possenniskie – two of New Zealand’s leading beer activists and visionaries – the Yeastie Boys have been brewing deliciously irreverent ales, picking up trophies, innovating, poking their tongues out at convention, and receiving critical acclaim since their launch in 2008.

Kamilla Kristensen
+44 7395 311297