Is Beer Yeast Underrated?

Yeast is fundamental to beer, but it doesn't always get the attention it deserves, says Adrian Tierney-Jones

Let’s be clear: no yeast, no beer. Yeast is the driving force behind fermentation, a ravenous beast that devours the sugars loosened from malt to create alcohol and CO2.

Top- or warm-fermenting yeast strains work with ale; bottom- or cold- with lager and let us not forget the wild strain of Brettanomyces, much beloved by Belgian Lambic brewers.

Yet, in spite of its crucial role, yeast is all too often overlooked. It is the poor relative at the brewing party, standing in the corner hoping that someone will say ‘hi’, especially as it has paid for the event.

Perhaps it’s the nebulousness of yeast that negates any sexiness. Hops? Think about wine lovers enthusing about grapes. Malt? Imagine fields of golden barley shimmering in sunshine. Yeast? Erm, would you really like to see a picture of a micro-organism that is a member of the fungi family?

‘Beer is a sum of its parts,’ says Derek Bates, head brewer at Norfolk’s much acclaimed Duration Brewing. ‘Without the water, malt and hops it wouldn’t be “beer” as we know it − that being said, yeast is the key to unlocking all those things and making them what they are.

Blend water, malt and hops together but leave out the yeast? All you have is a sweet, slightly bitter tea. Yeast is that prism into another world, a little bit of magic behind all the science.’

Unconvinced? Let’s change the story. During lockdown, Instagram pulsated with arty snaps of homemade sourdough loaves and starter yeasts; meanwhile breweries such as Burning Sky and Wiper & True have let Brettanomyces into their beers with stunning results. There is more to yeast than just fermentation.

‘Getting to know a yeast really well means you can coax a whole range of flavours from it that you can’t get from the malt and hops,’ says Adnams’ head brewer Fergus Fitzgerald. ‘However, it is complicated and susceptible to minor changes, so demands work and understanding. Yeast is the fairy dust that’s sprinkled on wort to create beer, except it’s better than fairy dust.’

Talking of fairy dust leads us to kveik (rhymes with Mike), which, thanks to the pioneering work of Oslo-based Lars Marius Garshol, author of The Lost Art of Farmhouse Brewing, has become the most stylish yeast to be let off the leash in the modern brewhouse.

Originating in the world of Scandinavian farmhouse brewing, fans champion its ability to ferment at high temperatures while also shortening fermentation time, which according to Wiper & True’s Michael Wiper, ‘means that brewers can turn their tanks around faster, which has a huge impact on productivity, capital outlay and space. Also, fermenting warmer means... less chilling’.

As for the sensory side of things, it can bring tropical fruit aromas and flavours, which complement the equally fruity characters of modern US hops, something I had to test with a can of Cheshire Brewhouse’s Lille Lørdag, a 6% abv ‘Modern Norwegian Farmhouse Ale’ that uses kveik. The beer pours a stylishly hazy orange-gold and has a ripe orange note on the nose, while the palate is more orange alongside an angular spiciness reminiscent of saison, before a refreshing, dry finish.

‘I’d been wanting to make a beer with kveik for a while,’ says brewery founder Shane Swindells, ‘and then I was offered the chance to brew using an heirloom barley, with the caveat that it hadn’t been malted well and would be difficult in the brewhouse. Then I remembered from reading various online information on kveik, that the small farmhouse brewers using the yeast also made their own malt. So I thought maybe it would be the best fit for this difficult-to-use ancient barley. I would love to work with more strains of kveik, as there are now a number available that give a variety of flavours and aromas, from orange to mushrooms and pineapple.’

For the Yeastie Boys’ Stu McKinlay, kveik has been such a revelation that it has become the brewery’s house yeast. Two US strains were usually used but, according to McKinlay, ‘they have limitations, while kveik adds more harmony. It is like adding a bass player to a band and all my favourite bands have a great rhythm section. The one we now use has a great orange ester profile and almost Belgian characteristics and adds just a little more complexity’.

Musing on how yeast can have a high profile in the world of beer, McKinlay adds, ‘think how sexy sourdough is, so maybe we can get people to think in a similar way about yeast, whether in lagers, Belgian beer or kveik’.

Kveik, however, is not the only fancy yeast strain to crash the party held by hops and malt. Bristol’s Lost and Grounded uses three separate strains: lager, Belgian ale and American ale. For co-founder and brewer Alex Troncoso, the four Belgian-inspired ales in the brewery’s core range are classic examples of their style and dependent on a Belgian-style yeast.

‘For us, the key aspect was to select a Belgian yeast which is low in phenolic character, so not overtly “spicy”,’ he says, ‘whilst still giving enough to the beer to make it distinct. Working with our yeast to produce balanced beers is a key aspect of our brewing philosophy.’

Then there is the New England IPA, fermented with Vermont yeast, a strain used by Fitzgerald for Adnams’ version.

‘We did try our yeast in it for a few batches,’ he tells me, ‘and while we got some of the flavours, we preferred the fruit in the versions brewed with the Vermont yeast strain. I think the pineapple notes particularly are more prominent,’ he explains.

‘One of my brewers reminded me earlier that as we have a house strain, we often refer to it as family, but for an older brewery like Adnams, you don’t get to choose your house strain. You can choose to embrace it though, quirks and all, and work with it to get the best things you need out of it.

‘Sometimes you have to accept that there are things it can’t do so you bring in your friends, like Vermont, to help out.’

You could argue that Kveik, Vermont and Belgian yeast strains are subtle in their influence, unlike the vivid flavours of new hops many beer lovers crave. However, what really matters is that yeast is another story brewers and bartenders can tell and should tell − and in these rather uncertain times, the more stories beer has, the more chance people will listen and taste.

Yeastie Boys, Gunnamatta Early Grey IPA 
Orange-amber, tea-infused IPA with both nose and palate demonstrating a generous citrus orange presence alongside the herbal note of bergamot.
6.5% abv, £18.50/12x330ml cans, £105/30l keg (includes delivery), Yeastie Boys.

Exale Brewing, Tropi
Tropical fruit sour with added pineapple and fermented with kveik − plenty of pineapple notes, juicy on the mouthfeel, tangy and refreshing.
3.2% abv, £56.67/24x440ml cans, Exale Brewing.

Lost & Grounded, Apophenia
Belgian-style tripel that is crystalline and brilliant in its citrusy fruitiness; full-bodied, effervescent and elegant.
8.8% abv, £59.95/24x440ml cans, Lost and Grounded.

Signature Brew, Sustain 
New England IPA with juicy mango notes on the nose, plenty of mango and passion fruit on the palate and a dry and gently bittersweet finish.
6.5% abv, £48/24x330ml cans, £128/30l keg, Signature Brew.

Left Handed Giant, Hazy Pale
Bristol-made pale ale which is fermented with a kveik yeast strain. Soft ripe fruit on the nose, with more fruit on the palate, a juicy mouth feel and a clean bitterness and dryness in the finish.
4.5% abv, £52.06/24x440ml cans, Left Handed Giant.

This article was updated from one that was originally published in imbibe live magazine on 26 Nov 2020.

(Prices correct at the time of publishing)