yeast

We love yeast, so shere’s always a yeast vote in a Not Yet Named vintage. I’m not directly including any excerpts from vintage emails in this blog, purely because it would be hard to pick which one. However, we have done all of these inoculation variations listed over the first 6 vintages; adding cultured yeast, adding fermenting juice (that had been inoculated with yeast), adding fermenting juice (that hadn’t), pied de cuvee and wild/spontaneous ferments and so have included every email if you want to click about. Those options increase in risk as you progress, and whilst I don’t know anyone who argues with that, everyone argues philosophically or experientally about which ones produce the best results.

methods

Adding Cultured Yeast
This refers to the addition of a cultured and commercially selected Saccharomyces cerevisiae strain to grape must. These strains are chosen for their reliability, clean fermentations, and the specific aromatic or textural qualities they encourage. This approach ensures a quick, predictable start to fermentation and reduces the risk of spoilage or stuck ferments. Reliable but sometimes accused of being one-dimensional.

Adding Fermenting Juice (That’s been inoculated with Yeast)
In this method, a small batch of grape juice is stolen from another ‘donor’ tank that’s already fermenting in the winery and added to kickstart fermentation. It allows you to select a proven population of healthy yeast and potentially adding in a touch of complexity, if the wine is different, from the donor tank.

Adding Fermenting Juice
Same as above, although there’s a more scope for aguing that it’s a wild/native ferment.

Pied de Cuve
This is a technique where grapes from the vineyard are harvested slightly earlier and allowed to ferment spontaneously (often in a bucket or small vessel) near the vineyard. In Slovenia, we wanted our bucket to start fermentation fast so we took it with us to dinner, hugging it for warmth and emotional support. Once fermentation is vigorous, this 'starter culture' is added to the main harvest. It's a more controlled way of encouraging spontaneous fermentation, using the site's own yeast population while reducing the risk of slow or stuck ferments.

Wild / Spontaneous Fermentation
No yeasts are added. The fermentation is allowed to start naturally using the native yeast populations found on the grape skins, in the vineyard, and in the winery environment. It's unpredictable and can be slower to begin, but often leads to greater aromatic complexity and individuality in the wine. “Wild” and “spontaneous” are often used interchangeably, though the latter emphasises the lack of intervention rather than the source of the yeast.

The Wild vs Commercial debate

In my experience, wild or spontaneous ferments have always stressed me out. I keep a fermentation diary and reading them back always makes me chuckle. I should publish them but they may need some censoring first.

You need patience, confidence, and good temperature control — a quiet intervention that’s very handy in making the whole thing work. I've had ferments kick off late, but once they start, they tend to fly. The first few percent of sugar consumption often comes from non-Saccharomyces yeasts, contributing complexity and a touch of volatile acidity (VA). Just a whisper of it that can vanish by the end of a ferment, but while it's there I’m terrified.

Being honest, cultured yeast is safer. You avoid stuck ferments, you avoid most faults, and you are more likely to get the wine you intended. “Lazy winemakers use yeast.” is quote often used jokingly on The Maker and the Merchant podcast but I would also say that I’ve found that inoculating in any method doesn’t take too much work, the only real nightmare is having to go through a restart protocol for stuck ferments, this is the one thing you can’t be lazy about. Check the monitoring written on the tank to see what’s needed.

“As an interesting anecdote we fermented a Grüner Veltliner with VL3 (a Bordeaux isolate) in California, and quite a few people blind tasted it as a Bordeaux white. It’s amazing that a yeast can unlock flavours that you might not typically associate with a grape/region. That’s wild, not literally. However, in our second vintage, a Cornas yeast used in Chile made no one think they were drinking northern Rhône.”

EXpression of terroir

I find this justification of any approach a bit challenging:

“I don’t/do add yeast because I want to express terroir.”

I struggle with the idea that any particular method of inoculation reflects a deeper connection to the land. Sometimes, it’s simply a matter of preference — and that’s reason enough. But the phrase “expression of terroir” really gets my goat. Why should one winemaker get to claim their wine is more authentic than another’s?

If someone picks a yeast because it makes a wine they love, that’s all the justification they need in my book. That’s not a betrayal of terroir — it might even be a clearer expression of it. In m view, terroir isn’t just soil and sun; it’s also culture, decision-making, and the human touch.

If most producers in a region ferment in a certain way — whether that’s with native yeasts or according to a specific nutrient protocol — that becomes part of the region’s identity. So who’s expressing terroir more authentically: the one following tradition, or the one leaving it to nature?

Maybe this is all part of the wider terroir debate for another blog, and I’ve wandered into it without meaning to. But I love the debate these yeast votes generate. That’s why I’ll always include one. In the end, all I want is my wines to reflect the people who decide how they’re made — that’s the Not Yet Named terroir.