Brett's in my beer!

Posted on May 12 2020

A brewer inspecting the beer as it brews

What’s all this about 'Brett' and what’s it doing in your beer? Brett is brewers’ quick hand for Brettanomyces, a wild yeast strain. It literally means ‘British fungus’! Not because we invented it, but because scientists discovered it – or at least put a label on it – when they were investigating spoilage in English ale.

So, yes, Brett does have its downside – it can spoil a whole fermentation of beer (and the same goes for wine), but it does have its upside as brewers have discovered.

Brett in beer can produce a whole range of flavours you’d never dream of – from farmyard funk to horse blanket – which is what makes it interesting. But before you turn away and think ‘off flavours’, that’s not for me … in the right measure, doing the right thing, it can add real dimension to a beer and even, on occasions, for you hop lovers, can provide hoppy flavours on overdrive.

Saccharomyces vs Brett

Here is the theory behind it. Most beer is fermented using the yeast Saccharomyces. It works quickly, efficiently and predictably (mostly), eating up the sugars to produce alcohol and CO2 – beer. Brett is like its outlandish cousin. It’s much better able to gobble up the longer sugar chains that Saccharomyces can’t tackle. It does this slowly, in its own good time and, as it goes, produces a whole range of flavours. Again, more of its own choosing, than anything a brewer dictates. And as it can eat up more of the long-chain sugars, it also lends texture and mouthfeel to a beer … and often makes it drier, too.

Brett is all around

Where do you find Brett? It’s everywhere. It grows naturally on the skins of fruit. So, in the old days, when beer was brewed in the open air, it would be the local Brett that would infect the batch and get the fermentation going. Today, Brett is the yeast you’ll find in a naturally fermented beer – a wild ferment. Or you can introduce it. Some might let the initial ferment take place with Saccharomyces, then let Brett take over, eat up the leftover sugars, and produce in it more exotic, funky flavours.

A family of Bretts

There are different types of Brett too – Brettanomyces Bruxellensis, the one encouraged in Belgian beers, tends to add a touch of horse blanket! You’ll notice its flavours in the traditional Lambic, Gueuze and Flemish red ales. There are five more Bretts – Anomalus, Claussenii, Custersianus, Naardenensis and Nanus in case you’re short of quiz questions at any time.

Brett on IPA hoppy overdrive

Now brewers have even discovered how to make a Brett IPA. This is when brewers use Brett for the initial fermentation, rather than Saccharomyces. They discovered Brett, especially if you don’t stress it (i.e. it’s in strong enough concentration), can be better behaved … reasonably quick at its job, and produce very vivid flavours, especially on the fruity side. It can make esters that give the IPA real tropical notes – like American hops on loudspeaker.

So, mostly Brett and its funky flavours, in the right measure, can add real complexity and uniqueness in a beer. They won’t be for everyone, but they’re fun trying.

Let’s leave you with the words of the great beer expert Michael Jackson (the author, not the singer!), who summed up Brett so perfectly:

“Saccharomyces is like a dog and Brett is like a cat. It’s a little less predictable. It’s going to do its own thing; it’s not going to come when you call it and sit when you say sit. If you can respect its individuality and suggest rather than dictate what it does in your fermentation, it can reward the brewer and the drinker.”

You can’t say it better than that!

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