Brett in Wine: What Brettanomyces Tastes Like, and When It's Too Much
Brettanomyces, or brett, is the wild yeast behind barnyard, leather and smoked-meat notes in wine. What it is, the compounds behind it, why it shows up in natural wine, and how to tell a little character from a fault.
If a natural red smells like a stable, a saddle or a smoked ham, you've probably met brett. It's the most famous source of "funk" in wine, and one of the most argued about.
What brett is
Brettanomyces (and its spore-forming form, Dekkera) is a genus of yeast. It's not the yeast that turns grape juice into wine. It's a hardy hanger-on that survives in cellars, barrels, hoses and, sometimes, on grapes, and it can grow in finished wine with very little sugar to live on. The Australian Wine Research Institute's Brettanomyces fact sheet are a good technical starting point.
“The AWRI fact sheet groups these as the "volatile phenols" behind the Band-Aid, medicinal, horsy and barnyard descriptors.”
What it tastes like, and why
Brett produces a handful of aroma compounds. The best known:
- 4-ethylphenol (4-EP): farmyard, horse, Band-Aid, medicinal.
- 4-ethylguaiacol (4-EG): smoky, spicy, clove, smoked meat.
- 4-ethylcatechol (4-EC): horsy, farmyard.
The AWRI fact sheet groups these as the "volatile phenols" behind the Band-Aid, medicinal, horsy and barnyard descriptors.
How a brett-affected wine smells depends on the balance between them, on how much there is, and on the wine itself. A big, ripe red can carry more before it shows than a light, fresh one.
Brett can also contribute to mousiness, a separate fault you taste on the finish rather than smell.
Character or fault?
This is where people disagree, and honestly so.
- At low levels, some drinkers find brett adds savouriness: leather, spice, a meaty depth. Some well-regarded classic reds have been known for a hint of it.
- At high levels, it takes over. The fruit drops away, the finish turns dry and metallic, and, the most common complaint, wines from different places start to smell the same. If a wine is supposed to taste of where it's from, that's a real loss.
Our working rule, the same one we use for all funk: can you still taste fruit and place under it? If yes, it's character you may or may not like. If no, it's a fault. Is funky wine flawed?
Why natural wine gets more of it
Conventional cellars control brett with three main tools: sulfur dioxide, sterile filtration before bottling, and rigorous cleaning of barrels and equipment. Natural winemaking uses little or no SO2 and often skips filtration. That leaves hygiene, acidity and temperature as the main defences, and it means a brett population that starts in a barrel can keep working after the wine is bottled.
That's also why brett can appear or grow over time: a bottle that was clean at release may show more brett a year or two later.
How to spot it
Smell first. Brett is aromatic, unlike mousiness, so it's usually obvious on the nose:
- Farmyard or horse, more animal than earthy.
- Leather or saddle.
- Smoked meat, bacon, clove.
- Band-Aid or a medicinal note at the extreme.
Then taste: does the finish stay juicy, or does it turn dry and metallic? Brett-heavy wines often lose their fruit on the finish.
Don't confuse it with reduction (struck match, rubber, egg; it usually fades with air) or with the earthy, savoury notes some grapes and regions give without any microbial help.
How winemakers keep brett in check
Every winemaker who skips sulfur and filtration has to control brett some other way. The usual approaches:
- Cellar hygiene. Brett lives in barrels, hoses, pumps and drains. Cleaning, and retiring old barrels that harbour it, does a lot of the work.
- Acidity. Brett grows more easily in higher-pH wines. Picking a little earlier, for fresher acidity, makes life harder for it.
- Temperature. Cool cellars slow it down.
- Time and topping up. Long ageing in barrel and air in half-empty barrels give brett time and oxygen. Many natural reds are bottled young and drunk young, partly for this reason.
- A little sulfur at bottling. Some producers who call themselves natural or low intervention add a small dose at bottling for exactly this reason.
None of that is guaranteed, which is why two bottles of the same wine can differ.
Brett at the table
If a wine has a little brett and you like it, it tends to sit well with food that's savoury already: charcuterie, grilled or smoked meat, mushrooms, aged cheese. If it has more than you like, food won't fix it, and a cool serving temperature only partly hides it.
Ordering around it
If you like a little wildness, ask for "something savoury, a bit wild". If you don't, say "clean but natural" or "no barnyard". Any good natural-wine bar has both, and saying what you don't want is just as useful as saying what you do. How to order natural wine
Related reading
- What is funky wine?: every source of funk, side by side.
- Volatile acidity: the other big one.
- Funky red and white wine: what to expect by colour.
- Glossary: brettanomyces
- The natural wine guide
Quick answers
Natural wine: the full guide
What it is, how it's made, the labels, the faults, and where to drink it.
Mousy wine
Mousiness is the one natural-wine fault almost nobody defends. What it tastes like, why you can taste it but not smell it, what causes it, why it varies from person to person, and what to do with a mousy bottle.
Volatile acidity
Volatile acidity is the tangy, kombucha-like edge in many natural wines. What VA is, the legal limits in the US and EU, how it tastes at different levels, why natural wine often has more, and when it becomes a fault.
Vin Méthode Nature
In 2020 France validated a voluntary label for natural wine, Vin Méthode Nature. What the charter requires, the two logos and their sulfite limits, who runs it, why most natural producers don't use it, and what it means when you see it.
Low intervention wine
"Low intervention" is on more and more wine lists. What the phrase usually means, how it differs from natural, organic and "clean" wine, why it has no legal definition, and the questions that tell you more than the label does.
Natural vs conventional
Natural wine vs regular wine, step by step: farming, yeast, additives, sulfites, filtering, taste, consistency and price. What the law lets conventional wine use, what natural producers skip, and what that does and doesn't mean.
Funky red & white wine
Funky wine tastes different in red, white, orange and sparkling. What "funky" usually means for each, where the funk comes from, which notes are style and which are faults, and how to ask for exactly the funk you want.