The local beer market has been dominated by lagers, ales and IPAs for many years, but sour beers are fast making their way into kegs and taps around the country. The acidic brew has been around for centuries in parts of Europe, but independent breweries are putting their own spin on the style.

Hospitality talks to Sydney brewers Karli Small, Nick Calder-Scholes and Jamie Webb- Smith on the art of making sour beer and why it has so much potential.

The origins of sour beer can be traced back to Belgium and central Germany, where traditional methods involved the spontaneous fermentation of wild yeast and bacteria.

Head Brewer at One Drop Brewing Co. Nick Calder-Scholes says its lingering presence has likely been unintentionally overlooked. “We were drinking sour beer forever probably thinking it was normal beer,” he says. “The most famous would be Berliner Weisse, which is essentially a sour wheat beer.”

Nick Calder-Scholes head brewer, One Drop

A defining factor of sour beer is its sourness and sweetness, typically achieved using fruit. Traditionally, a sweet component such as raspberry or woodruff syrup was added manually while pouring the beer, but some sours simply went without. “The original sours coming out of Belgium were un-fruited originally,” says Jamie Webb- Smith, Head Brewer at Yulli’s Brews. “They were just pure sourness with a bit of barrel character.”

In brewing, it all starts with wort, which is essentially beer before it undergoes the fermentation process. In a sour, it can be manipulated to create the desired acidity. “You can either have a wild ferment or a mixed culture ferment with yeast and bacteria,” says Karlie Small, head brewer and production manager at The Grifter Brewing Co.

Karli Small head brewer, Grifter Brewing Co.

“Or you can have a kettle souring process, which is mainly what we do at Grifter. It’s when you’re using the natural cultures that are in the grain to sour the wort or you’re adding lactobacillus or souring bacteria.”

At Yulli’s, Webb-Smith opts for malted grains as they naturally hold souring agents. The wort is pre-acidified as the grains are put into the liquid and held at 40 degrees Celsius for 48 hours. “With a normal beer, your wort would be about 5.4 pH; we aim to inoculate at 4–4.2,” he says. “The 40 degrees and that 4.2 pH stop any undesirable bacteria growth.”

Calder-Scholes describes modern-day sours as a “controlled infection” due to the presence of wild yeasts and bacteria. At One Drop, the difference between brewing a sour compared to a lager or an IPA is the process of hot side, where the ingredients are mixed and boiled, and cold side, which refers to the process of ageing and fermentation.

“Hot side takes six hours and we leave it in the vessel we boil it in,” says Calder- Scholes. “We essentially pitch the infection there, which would damage the entire brewery if it got out or we let it sit in there for three to four days.”

The tartness of sour beer lends itself to myriad additions that give breweries the opportunity to work on a signature product. The Dolly Aldrin range from Yulli’s sees different fruit and vegetable iterations combined with the same sour base.

“If you added beetroot into a normal beer, you probably wouldn’t get the same effect as you would a sour,” says Webb-Smith. “Because of the sourness, you can cut it with sweetness and the flavours become more bearable in a sour beer than a dark beer or an IPA. The fruit comes out a little bit more when you haven’t got so many hops or malt.”

For Calder-Scholes, the flexibility of sour beer is the perfect vessel to explore seasonality and minimise the brewery’s environmental footprint. “The industry is very wasteful regardless of what anyone says; we just try to be conscious of that fact and try to use fruit that is somewhat seasonal and local if we can,” says the brewer.

One Drop’s sour range is vast and fruit-heavy, with little to no bitterness. “We would’ve released over 50 different sour beers since we opened two and a half years ago,” says Calder-Scholes. “We had a whole fruit and flower series where we used edible flowers and fruits to balance the acidity.”

A sour can break up a brewery’s offering and add a point of difference. Pink Galah has been an iconic release for Grifter, which introduced the pink lemonade sour ale to the line up in 2018.

The beverage is ideal for the warmer months, with the fizz and tang heartily embraced by consumers. “For Pink Galah, you get the fruitiness and acidity because we add a lot of fresh raspberries and lemon juice into the fermentation,” says Small.

Pink Galah uses a pure culture of lactobacillus, a souring bacterium also found in yoghurt. The result is a beer that is drier on the palate and fruity in flavour without as much sweetness. “It can be considered sharper on the palate compared to other beers because it has a lower body, which makes it a refreshing summer beer,” says Small.

In recent years, sours have steadily made their way into the craft beer scene, and Australia is now playing catch up with major players. “Before I was at Grifter, I spent five years brewing in the US to be a part of the craft brewing scene over there,” says Small.

“Every brewery had its own sour beer and they were moving on to other trends. A lot of brewers around here are using the traditional European brewing practices, but a lot of the craft brewing we’re seeing is following US trends.”

Beer enthusiasts are certainly willing to get on board with the latest and greatest in the sector. “We’re finding the population is really into trying new things and it’s changing how Australians think of beer,” says Small.

Grifter Brewing Co.

Brewers are reaping the rewards of the mouth-puckering style, too. “As a brewer, I love making sours,” says Webb-Smith. “It’s probably my favourite style to make because I’ve got the chance to do something a little bit weird and wonderful.”