Sour hits sweet spot

A beer style that was largely the product of a lack of an imprecise science has found favour with the modern consumer – in a big way, as Jeff Evans reports


IN A BRAND NEW TASTING room in the north of Scotland, James Watt takes a sip from his glass, glances down at a warehouse filled with oak casks and murmurs the words “four-and-a-half million”. I almost gag on my beer. The managing director of Brewdog has just confirmed that his company has spent £4.5 million on this new unit and – get this – it will only produce sour beers. If you’ve ever needed evidence of how the beer world has been turned on its head, this is it.

Twenty years ago, the last thing most customers would have wanted in a pub or bar was a sour beer. To the lay person, a sour taste is a clear indication that something is not right with a beer. More scientifically, it reveals that the beer has been turned acidic, probably through the intervention of wild yeast strains or bacteria, and in most styles of beer that is, of course, entirely inappropriate. But that’s not to say there hasn’t ever been a market for sour beers.

In the early 19th century, many beers would have been sour and acidic, simply because brewing science and practices were imprecise, allowing rogue yeast strains and other microflora to invade the beer, especially those beers such as porter that were aged in oak tuns for several months. These faults were largely eliminated through the work of yeast specialists such as Louis Pasteur and Carlsberg’s Emil Christian Hansen, but the souring effect of wild yeasts, friendly bacteria and wood ageing continued to be cherished by a small cohort of beer drinkers long after these scientific advances.

In a rural area to the south west of Brussels, farmhouse brewing traditions lingered on, creating spontaneously fermented beers known as lambics. These complex, often beguiling beers are exposed to wild yeasts and bacteria at an early stage, as the wort – the sugary liquid created by soaking malted barley in hot water – is cooled overnight in large shallow vats called coolships. The acid-forming intruders then ferment the liquid as it ages in wooden casks over a period of months. The resulting beers are rather flat, sharp and vinous but they are often skilfully blended, sometimes with a vibrant younger version, to produce a sparkling drink known as gueuze, which can taste like a bone-dry, tart and acidic champagne. Fruit may also be added to create kriek (made with cherries) or frambozen (raspberries), for instance – the fruit not just flavouring the drink but introducing new sugars and wild yeasts for yet more fermentation.

Elsewhere in Belgium, different types of sour beer survived. The Flanders red and oud bruin (old brown) styles are essentially conventional red or brown ales aged in ancient oak vats to allow microflora that have been long resident in the wood to work their magic. Brewing names such as Rodenbach, Verhaeghe and Liefmans are still celebrated by enthusiasts. In Germany, too, sour beer clung on – just. The best-known example is the Berliner weisse, produced not by wood ageing or wild yeasts but by allowing Lactobacillus bacteria to acidify the beer during the brewing process. It is such a sharp-tasting drink that the locals add a fruit or herb syrup to take away the edge. Meanwhile, gose – a beer local to the Leipzig area – was made like Berliner weisse with acidifying bacteria but then, curiously, laced with coriander and salt. This style did actually die out but has now been resurrected, Jurussic Park-style, by brewers local and international.

But it is not simply the legacy of historic producers that spurs Brewdog and other breweries which are turning sour beer into the latest big thing. The thrusting craft brewing movement in the US has also driven things forward. Around the turn of the millennium, brewers in America recognised that drinkers’ palates had developed and that they wanted more than just the big, citrus hop notes on which the US craft brewing revolution had been founded. They understood the legacy of European sour beer brewers and headed in that direction. New Belgium in Colorado was at the forefront, helped by the fact that its brewmaster, Peter Bouckaert, had previously worked at Rodenbach. Cascade Brewing in Oregon also made this move, taking advantage of its proximity to the US wine industry to procure barrels for ageing. Since that time, other breweries have become sour beer specialists, including Jester King in Texas, which has developed a farm to provide fruits for its beers, and Wicked Weed in North Carolina. The fact that AB-Inbev, the world’s biggest brewing company, bought Wicked Weed in 2017 more than suggests that sour beer is on a profitable curve.


Now sour beer has spread all around the world, in some instances – as in the case of Cascade – building on the natural similarities with winemaking. This involves not only employing old wine casks but also sharing techniques, bearing in mind the use of wild yeasts, the ageing process and the concept of terroir. Sour beers also borrow from wine’s customer base. They call for a more mature palate than everyday quaffing beers and so attract wine connoisseurs who understand both subtlety and complexity and have an open mind about flavours. There are other growth areas, too. Sours also appeal to people who normally dislike beer because of its perceived bitterness and to those who welcome and understand acidity, such as cider drinkers.

The parallels with wine are particularly evident in Italy, where the sour beer market is remarkably mature, considering that until the mid-1990s the country had no small breweries. The 1,500 Italian breweries today know where their competition lies and keep a close eye on the wine market. To draw comparisons, they package beers in tall, shapely bottles and pitch their wares to the restaurant trade.

The concept of slow food developed in Italy, which points to a certain reverence for food and drink products that have been carefully crafted and need time to reach perfection. Again, sour beer fits the bill admirably. One of the most acclaimed Italian sours is Panil Barriquée from Birrificio Torrechiara near Parma. It is aged in cognac barrels and then becomes drier through another fermentation in the bottle. It has the elegance of a classic Flemish red combined with a delicate local accent from its suggestion of balsamic vinegar.

The UK is not, by tradition, a wine country, yet the reception given to sour beers, both classic and cutting edge, has been surprising. It is not unusual now to find supermarkets stocking classic Belgian brews such as Boon Geuze or Liefmans Kriek Brut alongside new generation sours from Thornbridge in the UK’s Peak District or Wild Beer in the west of England, a young business that is actually predicated on the idea of wild yeast fermentation and barrel ageing. Wild Beer even claims its own terroir, based on a yeast culture it has propagated from strains captured in a local cider orchard. Long-established British breweries have taken the plunge, too. Cornwall’s St Austell has produced a local version of kriek and Fuller’s has combined with the small Marble brewery to revive the naturally acidic Gale’s Prize Old Ale. At the Georgian Elgood’s brewery in Cambridgeshire, they’ve brought back into use two historic cooling vessels that had been lying dormant for years. These shallow copper tanks were never intentionally used to make sour beer, but now they do just that, fathering a small range of beers in the lambic style that – with a nod to their Belgian inspiration – are marketed under the name Coolship.

Clearly, Brewdog has seen plenty here to bite into and it has shipped in former Wicked Weed brewer Richard Kilcullen to head up its sour project, which has been given the name Overworks. Kilcullen’s approach to the concept is meticulous, based on precise science and good practice rather than, as he puts it, “letting the sticks fall where they may”, which some people might assume to be the case with such an offbeat style of brewing.

He’s also pragmatic and measured about how sour a beer needs to be. “I’m not a shock doctor,” he says. “I’m here to create balanced, sessionable beer that’s complex and enjoyable but I’m not going to make something sour for sour’s sake.” He offers a glass of a beer he calls Pyraster. This is a pear sour, partly fermented with wild yeast harvested from local blackberries. It has the definitive wild yeast dryness and a pleasantly tart, fruity flavour but it’s not mouth-puckeringly sour or acidic.

There will always be beers out there that really curl the tongue and recede the gums, but sour beer, as Kilcullen rightly points out, can also be delicate, the acidity and tartness providing just a refreshing alternative to the mainstream.

Surprisingly to many drinkers, it is often far more accessible than its name suggests and perhaps explains why James Watt seems rather sanguine about the large financial commitment Brewdog is making. This is one investment that may leave a sour taste in the mouth for all the right reasons.