The “taste of New Zealand” is about to turn up in a beer, thanks to the amazing work of the team at Froth Tech who’ve isolated a wild brewing yeast from Aotearoa’s wilderness.
The yeast strain, named Wilding, will be used in a beer of the same name brewed by Emerson’s and available late on November 10*.
Froth Tech founders Simon Cooke and Ryan Carville say the yeast is like Farmhouse or Saison yeast and produces the kind of rustic flavours you’d expect but with some added complexity that includes a banana note and some sweet esters that offset the super-dry beer it creates.
The yeast they’ve managed to capture is different from cultures that are used in the production of lambic-style beers crafted by the likes of Craftwork and Garage Project. The difference is that those are brewed with mixed cultures of lots of bacteria and yeasts, while the Wilding yeast from Froth Tech is a single isolated strain of Saccharomyces cerevisiae or brewer’s yeast.
Cooke and Carville have been searching for a wild New Zealand yeast for a few years, harvesting small samples of berries, plants and setting air traps.
“We went out in the bush in Northland, the west coast of the South Island, the Rangitīkei District and Hawkes Bay – we were looking for places quite far away from breweries, to make sure whatever we found wasn’t just some commercial yeast that had blown in from a brewery” Carville explains.
Wilding was isolated from an air trap alongside a river close to Hunterville in the Rangitikei region. “It was pristine and remote, with wild bees and blackberry bushes nearby,” says Cooke.
They have built a library of 400 yeast-like isolates, and each of those had to be worked on to separate yeast from other bacteria or fungi.
To do that they worked with Callaghan Innovation, where their bioprocessing and fermentation team inoculated the samples into selective growth media to inhibit lactobacillus and other organisms, while encouraging growth of yeast cells.
The resulting growth was streaked out onto agar plates. If what grew looked like yeast, they isolated it and grew it further. The yeast-like isolates then went into a “bootcamp” featuring stress tests such as how well they handled different levels of pH and alcohol.
Around 90 “promising contenders” went back to Froth Tech for benchtop brewing experiments to see if any of them would make beer.
“We were looking for the ability to metabolise sugar, or how well it attenuated, and other characteristics such as flocculation, rate of fermentation, and of course sensory profile,” explains Carville.
Looking for good performers
Of those first 90, many struggled to perform in a manner appropriate for brewing. “But one did very well. It had 94 to 95 per cent attenuation, which is crazy high, and then showed an awesome sensory profile.”
They propagated that yeast further and sent to Emerson’s for a pilot brew to see if it would work in a commercial brewery.
Carville said the finished beer was similar to a saison. “It’s phenolic, there’s a lot of banana – which is more Hefeweizen-like, but there’s also this lager-like character, it finishes very clean. So it’s an amalgam of styles.
“It’s very dry, with a bouncy fruitiness, and you get sweetness from the esters. It’s unusual as it’s perceived as sweet but finishes really dry,” adds Cooke.
Emerson’s brewer Mason Pratt who created the recipe was delighted with the experience.
“We are absolutely thrilled to do the first commercial brew with this yeast. It’s not every day that you get to try out a yeast strain that hasn’t been used before.
“We decided to go with a light base of pilsner malt and wheat with just a hint of Wakatu hops to really let the yeast be the star. It was a pleasure to brew with and had great aroma right through fermentation. Notes of pear and apple with hints of banana and subtle warming spice notes. It ferments out really dry but maintains a great mouthfeel, similar to some saison yeast strains.
“I look forward to seeing what the New Zealand brewing community does with this strain as it lends itself to a range of Belgian styles but will work well in more hop-forward beers.”
Why Wilding is unique
The question is: how do they know it’s a unique yeast? There are over 1500 known species of yeast in the world, and hundreds of isolated strains of brewers yeast that have been domesticated in breweries over past centuries. It’s basically impossible to cross-reference it against other strains without doing expensive whole-genome sequencing. But as Carville explains, “It’s been isolated from a sample captured in sterile growth medium out in the wop-wops. We’ve also had this strain analysed via PCR and validated that it is saccharomyces cerevisiae and that it has the ‘diastaticus’ gene found in wild yeasts.”
Cooke adds: “It’s kind of like wondering if your own fingerprint is unique. It is basically impossible to prove without taking a fingerprint of the genome, which, unlike dipping your fingers in some ink, takes a bit more investigation. With such diversity of variations, you can feel confident that yours is unique. There is an enormous diversity of wild yeasts in the natural world, and when you’re on a small island in the South Pacific and you go to an area well away from people and breweries and take a sample from the air, you are capturing wild microbes that make up the microflora of that region, that valley, that tree, and that is unique.”
Wilding yeast will be released on the back of Emerson’s beer launch on November 10 and Carville says it’s a chance for people to “taste New Zealand”. Whether you’re a craft connoisseur or a punter who just wants to know ‘what does a wild New Zealand yeast taste like?’ the Emerson’s release will be a must-taste.
Wilding was named by Steph Coutts, a trained cicerone who runs Wellington’s Craft Beer College. She earned the right to name a yeast as part of her contribution to the Froth Tech crowdfunding campaign.
The new yeast strain has become available just as Froth Tech sealed a trans-Tasman distribution deal with Cryer Malt.
“It’s a really good partnership,” Carville says. “They are looking to add products to their range that they can supply to their brewery base and we were looking to enter the Australian market. This allows us to do that without a heap of resource or distraction from what we do best, which is producing New Zealand-grown fresh liquid yeast.”
Meanwhile at Wild Workshop
Just as Wilding was launched, Garage Project came out with their own “kiwi” beer, Toru.
It’s brewed with a mixed culture of New Zealand native yeasts and barrel-aged in a massive native timber barrel that Wild Workshop brewer Dave Bell stumbled across.
“I found the 2800-litre totara barrel for sale online in Northland, used for port previously. It took us over 18 months to get the barrel holding liquid.
“We then used all NZ malt, NZ hops and hoped to use all NZ microbes. We trialled numerous native caught strains but struggled with consistent results for primary ferment. After mixed results we decided on a primary ferment using a commercially available Saison strain before racking to barrel and then adding our favoured blend from our numerous ‘caught’ native ferments which we now have banked along with a handful of native Brett strains.”
While Garage Project have a number of mixed strains, they’ve not yet isolated on as Froth Tech have done.
“We have done a whole series of beers with solely native strains but have never isolated one to use on its own,” Bell says.
“Our favorite blend was caught off a hopbine, which became one of my favorite beers from Wild Workshop as a single barrel release. This was a blend of two native saccharomyces, one pediococcus and two Brett strains.
“I think the Wilding strain is super interesting and would like to move towards something like this for our primary ferment strain for Toru in the future.”
* This beer was originally set for release on October 27 and the story has been updated to reflect the new release date of November 10.