Wild microbes can infect beer with surprising and creative new flavours.
Field Studies is a monthly column by Clare Watson, who travels around Australia and the world exploring science by participating in studies, visiting research institutes, going on trips with scientists, and a lot more.
The Oak Barrel, Sydney, Australia
Wednesday, April 5th
Ashley Huntington wants to make a beer that tastes like where it comes from. A winemaker by training, 12 years ago he bought a farm that is encircled by the River Derwent in Tasmania. He says it hosts the best vineyard site in the country – but he never got around to making that wine. In the time that it takes to grow a grape, three years, Ashley thought he might as well try his hand at brewing beer.
He spied a paddock of hops across the river, picked the flowers whole. He planted an 80-hectare barley crop, malted it, and threw in some water straight from the river – filtered but not microbiologically denuded. The brewing tank was housed in a holey hay shed beneath a forest of flowering Tasmanian blue gum. Carelessly, since it was just an experiment, Ashley left the lid off the tank as it was brewing overnight. He came back the next day to find a beer – but not as he knew it. It was sour.
More than a decade later, Ashley is still experimenting with wild ferments, allowing nature to do its work on the grains that he grows. Turns out, his sour ale was fermented by lactic acid bacteria, the indigenous microbes on starchy grains like barley, rice and wheat. The bacteria drive a lactic acid ferment, which produces a sour taste – a deviation from the more common yeast-driven ferment in wines and other beers but it’s the same mob that are active in yoghurts and sourdough cultures.
The results are surprising. The first beer to taste was the Derwent Spelt Ale, a naturally soured ale, served at room temperature. The full flavour of mixed cereals – barley, buckwheat and spelt – comes quickly, and without the usual heavy aftertaste that hangs around after a sip of beer. It was light and refreshing but not carbonated, like a traditional Spanish sidra, which is made from fermented apples.
Next we tried the bitter amber ale, then moved onto a dark apple ale and a sour cherry ale drawn straight from the barrel. As we sampled the Two Metre Tall collection, sipping beer from bell-bottom glasses, Ashley shared tales of his wild ales. Like the time he struck up a collaboration with an oyster farmer on Bruny Island, throwing the deep-sea molluscs and some seaweed into a brew. The oyster farmer turned his nose up at the stout, so Ashley stashed it in the shed (he never throws out a brew because who knows, it might come of age) and rediscovered it seven years later. It tasted pretty good: a dark stout with a dash of salt, like a miso broth, that keeps you coming back for another sip out of curiosity and thirst.
Watching Ashley pace back and forth, his arms flailing and hair floundering, he looks more like comedian Ross Noble than a conscientious vintner, let alone an organic chemist. He delivers his story, an ode to the land, with the vigour of a spoken word poet, taking a breather from time to time, leaning against the wall behind.
As Ashley pointed out, we’ve been enjoying fermented goods for millennia. We have the Egyptians to thank for sourdough and the Sumerians, the settlers of modern-day Iraq, for beer. Later, the Vikings indulged in mead and the Romans feasted with wine. Moreover, fermentation was used as a technique to preserve meats, cheeses and vegetables long before refrigeration. Now, fermented foods are the staples of different cuisines around the globe. What would Japanese be without miso, Korean without kimchi or a German bratwurst without sauerkraut – better yet, a Sunday farmers market without kombucha?
Since I’m a baker, not a brewer, I tried to start my own sourdough culture, whisking airborne yeast through flour, and for a few days I thought I had it. The culture was fermenting vigorously on a balmy Sunday afternoon but a crisp autumn morning followed and my short-lived starter was toast.
It was French chemist Louis Pasteur who deduced in 1857 that fermentation is the hard work of yeast, single-cell microorganisms, that convert sugars into alcohol, bubbles of carbon dioxide and other acids. Yeast don’t care so much for the alcohol; they use the energy that the reaction yields – and bacteria want to join the party too. While he was writing his paper on fermentation, Pasteur was approached by an embittered distillery owner whose product had soured, apparently contaminated, and he found lactic acid bacteria to be the culprits.
This idea, that anything other than a controlled inoculation of a chosen yeast is a contamination of the brew, still dominates mainstream brewing practices today. Wild ferments are scorned, described by some as nefarious or deviant, which goes against centuries of traditional Belgian lambic brewing practices. Born from spontaneous ferments, lambics are proudly brewed alongside the Senne River, southwest of Brussels, in the Payottenland valley. Brews are purposely left overnight in shallow open vessels, called koelschips, and aged in old oak barrels so that local microbes can take seed.
In lambic beers and Ashley’s untamed brews, the natural fermentation cycle runs amok over three years, creating flavours as complex as fine wines. First comes wild yeast on the air, then a few months later lactobacillus get to work, souring the brew. At the back end of the ferment, most of the year already passed, brettanomyces yeast begin to mature the drop, adding fruity notes or smoky tones. It’s a harmonious mix of microflora and there can be thousands of strains at play.
Never knowing which bugs are in the beer, and because a genuine wild ferment is unpredictable, Two Metre Tall pints come with a disclaimer: expect bottle and brew variation. Where other conventional breweries bottle their product after their ferment-of-choice is finished, Ashley’s brews continue to ferment in the bottle – which you can try for yourself. If you were to buy a case of twelve and try one a month for a year, each bottle will taste different.
“Sometimes it will blow up in your face, then it will calm down, then it will go again, then it will taste like this, then it will give you that. I am yet to plant the vine on the world’s most remarkable vineyard because I am absolutely fascinated watching these critters work. I made a rotten mistake that turned out to be the loveliest thing I’ve ever done in my life,” says Ashley – and he is married with children.
In this regard, Ashley has returned in a roundabout way to his scientific roots. Bold experimentation and chance discoveries are a part of science along with meticulous testing and re-testing. Take Alexander Fleming for example, whose bacterial cultures were accidentally contaminated by mould, which thwarted the bacterial growth in some places – giving the world its first antibiotic, penicillin; or the Australian doctor Barry Marshall, who audaciously swallowed a soup laced with Helicobacter pylori to prove that bacteria, not stress, caused stomach ulcers.
There is a complex – and undoubtedly active – microbial community that naturally resides in the healthy human body, and which scientists are furiously trying to understand. Microbes colonise our skin and gut from the moment we are born. Carrying genes that we do not, the gut microbiome can affect your moods and immune system. The presence of certain bacteria can aid digestion and on the flip side, what you eat (or drink) can rapidly change your microbiome. So, if sour beers are to your liking, they might add some good bacteria, as yoghurt does, to the tens of trillions of gut microbes already in the mix.
Edited by Jack Scanlan
