A yeast known as the ‘British fungus’, which once defined the flavour of British beer, is being embraced by a whole new generation of brewers. Food writer and brewer Daniel Tapper explains
Words: Daniel Tapper
Transport yourself to the 1800s for a moment. You enter a pub and order a pint. But wait, there’s something wrong. It smells sort of like a barnyard or the undercarriage of a freshly used horse blanket (if you can imagine such a thing). More baffling still, it has flavours reminiscent of compost and fermented silage. Without a moment’s hesitation you proudly proclaim: “This pint is off!”
But you’d be very wrong; in fact, if your pint didn’t taste like this 200 years ago, then you’d probably send it back. Why? Because these aromas and flavours would have appeared—to varying degrees— in almost every pint served in Britain up until the 20th century.
More surprising still, these peculiar flavour descriptors have in recent years become the holy grail of a new generation of craft brewers seeking to reignite one of Britain’s most flavoursome—and least appreciated—natural ingredients: Brettanomyces.
Wild genus of yeast
This wild genus of yeast (which translates as ‘British fungus’) once thrived in Blighty’s beer, much of which was aged for up to a year in unsanitary giant oak vats before being blended with younger beers for serving. During this time, the presence of ‘Brett’ in the unclean timber would transform normal-tasting beer into something altogether more complex, displaying characteristics that many today would describe as sour or stale.
Far from being judged unworthy, these aged beers would sell for up to three of four times the price of younger beer. And Brits weren’t the only ones who appreciated this unique fungus. In Belgium, Brettanomyces was (and still is) harnessed to create farmhouse saisons, lambics, gueuzes, cherry-aged krieks, Flanders red ales and some bottled Trappist beers.
More recently, Belgian Trappist brewery Orval began secondary fermenting its beer with Brett in the 1930s, giving it a famously ‘funky’ flavour.
Sadly, not all of our ancestral brewers shared the same enthusiasm for Brett. As the brewing process was gradually rendered cleaner, Brettanomyces’s acidifying character began to be seen as an off-flavour. Indeed, Danish brewers were so terrified of their beer achieving ‘English character’ that they invested vast sums of money attempting to find out how they could prevent such flavours existing in their own brews.
The nail in Brettanomyces’s coffin came in 1904 when a scientist working for Carlsberg isolated the strain, thus unleashing a mad dash for the development of pedigree yeast strains. By the 21st century, Brettanomyces was all but extinct in mainstream beer.
Fortunately, craft brewers from across Europe have once again begun harnessing the power of this most British of yeasts. In Denmark, The Rocket Brewing Company (a Brett-only brewery based in Copenhagen) makes a Belgian triple with cane sugar, organic oranges and a pure strain of Brett known as Brettanomyces bruxellensis.
In Britain, Somerset brewery The Wild Beer Co creates flavourful beers using Brett foraged from the skins of locally grown fruit and in the USA, American craft breweries Green Bench and Trinity have created a Brett-fermented saison aged with sauvignon blanc grape must.
So the next time you decide to send back an ‘off’, ‘stale’ or ‘sour’ beer, be sure to check the label first.
Three of the best wild ales from Borough Market’s Utobeer:
The Wild Beer Co, Evolver IPA (5.8%)
Enjoy it fresh as a fruity pale ale or put it away to age. Over time (six months at least) this 100% Brett fermented beer from Somerset develops a far dryer, more complex character, making it the perfect bedfellow for moules frites.
The Rocket Brewing Company, Ruby Cherry Sour (7.7%)
This outstanding Danish beer goes through no fewer than three fermentation cycles with the help of brettanomyces and raw unpasteurised sour cherries. The result is a dark red beer with a very intense cherry profile and a subtle almondy flavour. Perfect with soft fresh cheese like burrata or mascarpone.
Orval Brewery, Orval (6.2%)
Ask any beer aficionado to name a beer that displays perfect Brett character and chances are they’ll name Orval. This brassy-orange pale ale from an authentic Trappist brewery in the Gaume region of Belgium is teaming with complex earthy flavours of clove, white grape and lemon. For maximum flavour, store it for at least six months and enjoy with parsley and lemon steamed white fish.