There’s been a bit of a furore about wild yeast fermentation over the past month.

The fires were stoked by new research published by scientists at the University of British Columbia and authored by graduate student Jessica M. Lange, summarized in Wine Business Monthly: “Regardless of which yeast started the fermentation—indigenous or otherwise—a dominant commercial strain took over during the process, essentially wiping out any other forms of yeast that might have been present.”

vineyards near eguisheim - alsace

Shock blogger Tom Wark gleefully titled his commentary “Wild Yeast Fermentation – ‘There’s No Such Thing.’” Alice Feiring, first lady of the natural wine community, offered a more considered response, pointing out what she claimed to be some rather obvious flaws in the study. Anyone who has read Jamie Goode’s excellent Authentic Wine which deals with this subject extensively, might have wondered what all the fuss was about.

What is it about this subject that makes it so divisive – and why is it important to winemakers?

First some theory – we all know that grapes need yeast to ferment and metamorphose into wine. Until the 1980s, it was still common to allow fermentations to start spontaneously, with yeasts that were naturally swilling around in the atmosphere or on the bloom of the grapes. But then came new world winemakers, who advanced the science of yeasts by isolating the most efficient strains and reproducing them in laboratory conditions – thus creating the cultured (or “selected”) yeast industry.

It’s now common in both old and new world wineries to blast grapes with a dose of sulfur dioxide as they enter the winery, removing some of the the “local” or wild yeasts and bacteria, and then to inoculate with the winemaker’s chosen cultured yeast. The results are more predictable, fermentation can typically be completed more quickly and the risk of volatile acidity or spoilage yeasts like Brettanomyces joining the party is lessened.

A wine style that we now take for granted – simple, young, fresh, fruity white wines – might well not have become so ubiquitous, or easily available had it not been for the cultured yeast revolution. This was a tool that winemakers could use (together with good hygiene) to make consistent, squeaky clean wines that were not spoiled by rogue cultures, volatility or oxidation.

Countering this trend, more radical winemakers increasingly stress that wild yeasts are a vital part of terroir expression and integrity. Biodynamic guru Nicolas Joly has said “natural yeast is marked by all the subtleties of the year. If you have been dumb enough to kill your yeast, you have lost something from that year”. Some winemakers go further, suggesting that inoculating with a selected yeast is like asking another man to sleep with your wife, to father your child.


Let’s step away from all the bluster on the blogosphere, or the rhetoric of high profile wild yeast exponents, to the quieter climes of Alsace, in Northern France.

Alsace is unique as a high quality French wine region in its focus on varietal wines. It’s the only AOP region in France where the grape variety is permitted to be displayed on the label – with noble varieties riesling, pinot blanc, pinot gris and gewürztraminer leading the charge. Over 90% of production is white wine, and there are a bewildering variety of soils and terroirs spread over 15,000 hectares and 51 designated grand cru vineyards.

You might think that a region focusing on fruit purity and elegance would welcome the predictability and control of cultured yeasts with open arms. But that’s the interesting part. They don’t.

Organic and biodynamic viticulture are extremely popular here, with many high profile producers (Albert Mann, Josmeyer and Zind Humbrecht to name a few) having converted and certified over the last few decades. And whilst there may be no regulations that stipulate it, most biodynamic producers would not be caught dead using cultured yeasts in their wineries.

Spontaneous fermentation – to use what might be a less contentious term – is popular in Alsace. Winemakers here rarely add cultured yeasts as a matter of course – although some will intervene if fermentation is not progressing well, or if the wild fermentation would result in an off-dry wine – something that can easily happen in hotter years, with very ripe sugar-rich grapes.

I talked to a range of producers and sampled their wines during a visit to the region in May 2013, to get more understanding of the importance of yeast selection.


barmes-buecher-signageI first met Genevieve Barmès-Buecher at London’s Rawfair in 2012. I was stunned by the complexity and purity of her estate’s rieslings and gewürztraminers – even more so when I realised they were all produced from spontaneous fermentations. Any misplaced ideas I’d had that this technique could only produce rather rustic or even clumsy wines were quickly blown away.

Genevieve’s husband Francois died unexpectedly during the harvest in 2011, having been one of the biodynamic pioneers in the area. Genevieve told me “I rang Max (my son) and said, you have to come and help me finish the vintage. He was amazing – he’d watched his father work for many years, but now he had to do it for himself. Somehow we got through it and everything worked”.

genevieve-barmes-buecher-tasting-roomThe Barmès-Buecher way is to accept that each vintage is different, and to let the wine take its own path – and because no cultured yeasts or enzymes are ever added to the ferments, that can mean wildly different residual sugar and perceived sweetness from year to year. For example the Riesling Grand Cru Steingrübler ranges from 21 g/L (2.1%) RS in 2007, to almost none in 2009. Both wines are successful in their own right, though the 2010 tops them both in potential and balance.

You could argue that such huge differences in style from vintage to vintage, from dry and austere to rich and honeyed are problematic for the consumer. But these are wines that will always be hand-sold to connoisseurs, who one hopes appreciate the variety – and the intense relationship of the finished wine to its vintage conditions.

Domaine Weinbach

Laurence Faller, now the head winemaker at Domaine Weinbach, is of a similar mind to the Barmès-Buecher family. Her watchwords for the wines are finesse and elegance, but she’s happy to let vintages dictate the style.


Domaine Weinbach has been biodynamic since 1998, having previously already been farmed organically. Laurence told me advisedly “I never make it a religion – it’s more of an attitude or a belief”. Needless to say, cultured yeasts are never used chez Weinbach. Botrytis (“noble rot”) is welcomed in small quantities, even in the dry wines.

When tasting the estate’s impressive range of Rieslings, I was struck by the fascinating range of aromas and flavors, from lime leaves, apricots and petrol in the Grand Cru Riesling Schlossberg, to the more mysterious smoky, slatey Cuvèe Theo. Again, there is significant vintage variation in terms of sweetness and richness, although each Grand Cru has its own detectable style.

Zind Humbrecht

cellar at Domaine Zind-HumbrechtNo-one I visited takes the “laissez-faire” aspect of wild yeast fermentations further than Olivier Humbrecht. Another staunch convert to biodynamics, Humbrecht has some 100 different parcels of vines spread about Alsace, including the prized Rangen de Than Grand Cru – a vertiginous plot with volcanic soil which produces extremely fine Riesling and Pinot Gris.

It’s quite normal for the Zind Humbrecht wines to take 9 months to ferment (rather than the few weeks that is more standard for cultured yeast ferments). One barrel of a 2010 Selection de Grains Noble (an intensely sweet botrytis-influenced wine) is still slowly fermenting, having stopped and started several times through the winters.

There’s nothing random or ill-considered about the finished wines, which are supreme in their finesse and assuredness. Olivier also allows malolactic fermentation to take place naturally, leading to some toasty complexity on some of the noses.

Maison Trimbach

Here is an estate which needs no introduction – The Trimbachs produce what are often acclaimed as the world’s finest Rieslings: Cuvèe Frederic Emile and Clos Sainte Hune. They also happen to be one of the largest properties in Alsace, producing around a million bottles a year.

jean trimbach with the tasting lineup

Jean Trimbach told me disarmingly “we just produce the wines we love to drink”.  The Trimbach methodology is almost a polar opposite to Genevieve Barmès-Buecher ‘s way. The house style, sometimes jokingly referred to as “Protestant” due to its perceived austerity, is for bone dry Rieslings with mineral expression and powerful acidity. This is achieved year in, year out, sometimes by picking earlier (to avoid undue ripeness and sugar) – and by intervening with cultured yeasts, if it looks like the wines won’t ferment to dryness.

old bottles at Trimbach

Trimbach did mention, however, that in 2010, wild yeasts were sufficient for the entire fermentation. And on tasting the 2010 Rieslings, the word “elegance” kept on appearing in my notes – none more so than the youthful, incredibly taut and energetic Clos Sainte Hune.

Domaine Paul Blanck

frederic-blanck (domaine paul blanck)Domaine Blanck are producing some of the best value wines I’ve tasted in Alsace. Grand Crus Furstentum and Schlossberg are especially fine, and the Furstentum Riesling SGN 2007 was the finest sweet wine I’ve tasted in years, quietly trouncing anything else encountered on this trip.

Winemaker Frederic Blanck is down to earth and pragmatic to a fault. He told me “I want to produce the best wine I can – and I don’t need biodynamic certification to do that. I just need a marketing budget to help me sell it!”.  He is however passionate about the family’s terroir, mentioning that “Grand cru vineyards are special places to visit”.

Frederic may not be a devotee of biodynamics, but he prefers spontaneous fermentations and rarely intervenes. When I asked him why, the answer came quick as a flash: “Because it’s cheaper!”.

Consistency or vintage expression?

It’s clear that there are two distinct approaches in Alsace – the more interventionist stance as practised by the Trimbachs, to ensure wines that are consistent both stylistically and in terms of their sweetness level, or the laissez-faire ideal of the biodynamic estates, for whom vintage variation is as much a part of the style as anything else.

Even for the interventionists, adding cultured yeasts is seen as a corrective – not a baseline. And if the expressiveness and individuality of the wines I tasted is anything to go by, wild yeasts are playing an important part in expressing the varied terroirs between the Vosges mountains.

I’d wager that most Alsace winemakers would just laugh at the assertion that wild yeast fermentation does not exist.

Edit: A previous version of this article misspelled the name of Laurence Faller. Palate Press regrets the error. The title of Tom Wark’s article has also been corrected.

25 Responses

  1. Arnold Waldstein

    The best phrasing I hold to is:

    Cultured yeasts are the tools of the winemaker who paints with flavor. Wild yeasts are natural force to assist the winemaker who creates wine like a sculpture finds shape in a stone. The less chisel hits the more true the image.

    The same is true, in my mind, to the natural winemaker, who at the best,is a sculpture.

    • Arnold Waldstein

      Mine–I used this phrase almost 4 years ago in a very very early post on Natural Wine.

      There has to be some benefit to being a mashed up English/Poetry/Theater/Film/Philosophy major back when.

  2. Dwight Stanford (via Facebook)

    These spontaneous fermentations articles are just really getting me down. No one wants to look at the science and those who are fans are living in a dream world. The most you can say for S.F. is a wild yeast from the vineyard MIGHT start the fermentation in the winery if the must is not sulfited, but it will rapidly die off as the alcohol levels get higher and you will either get the colonized yeasts of the winery taking over which have been there for years and is dominant or you will get a stuck fermentation, which is a load of fun to re-start in some cases. Trimbach seems to be playing the game honestly, at least they say they are ready to inoculate if fermentation slows down.

  3. Tom Wark


    Excellent take on the issue.

    One thing. You’ve attributed a quote to me, when I said nothing of the sort.

    Also, “Shock blogger”? Hmmmm. Ok.

    • Arnold Waldstein

      Tom–wear this one with a wink. I’m a fan of yours as you know but yes, you do like to shock to elicit response.

      Honestly, that’s how I see you at times as well;)

  4. Deborah Heath

    Simon, thanks for this worthwhile recognition of the wonderful vintners of Alsace, and for contributing to this interesting ongoing discussion about spontaneous fermentation.

    As for the grad student study that you, Alice Feiring, and others have mentioned, some have questioned the research design, and others have underlined the importance of what happens in the vineyard in establishing robust wild yeast colonies. See exchange between Alice and Jason Lett (Eyrie in Oregon) on Twitter, for example.

    (p.s. Edit spelling on Laurence Faller’s name…)

  5. Michael Donohue

    GREAT ARTICLE*! I recently “took issue” with a colleague on this subject, and like many issues, it was semantic: it boils down to “wild” and “resident” yeast, being “all natural”…I cited Paul Draper’s “indigineous” on the label to mean only wild but Chris, a Davis grad, rightly pointed out that other local yeasts often take over and finish what the yeast(s)on the grape has started – you can watch them in a lab! From my unscientific standpoint, I would guess these other yeasts lurking about might take the wine from 10 to 13%…*Mostly because I sell or have sold all but one producer you mention and am very familiar with a number of them. Having said I must add that vintage variation in theory is an interesting concept but from a practical perspective (shopper/chef)irritating as hell, particularly I have found in Alsace. It is completely irksome to lay down good money (GC or otherwise), expecting a crisp dry wine and you get this tropical mush instead – almost regardless of varietal. So while I wish Alsace had jumped on/ modified the IRF scale sooner (the sliding scale of sweetness I consider the best consumer innovation since wine, I was happy to learn from a rep recently that Zind-Humbrecht from the 2012 vintage will be adding a sugar code of 1-5 on the front label. Trying to learn more!

    • Simon Woolf | The Morning Claret

      Yes, I’ve seen recent vintages of Zind Humbrecht with this scale. Paul Blanck does something very similiar, as do some other producers in the area.

      Stephen Brook makes a point that producers should use the term “Vendanges Tardive” if there is significant residual sugar (as it virtually always means the grapes were harvested late and had significant sugar content. I can understand that some winemakers prefer to keep this distinction for true desert wines, but there is an argument that it ought to be used more, to provide an easier guide.

    • Simon Woolf | The Morning Claret

      Hi Daniel,

      Many of the wineries I’ve featured in this piece are small family outfits (eg: Barmes Buecher and Paul Blanck).

      Trimbach are large in output and profile.

      Zind Humbrecht and Domaine Weinbach have a big profile but their output is tiny (c. 50K bottles per year in each case if I remember correctly – don’t have my notes to hand right now).

      The aim was to show a good range.


  6. Joel Peterson

    Beautifully written Simon. You very neatly straddled the line that is required for productive discourse on this subject. As you may know we use Spontaneous fermentations here at Ravenswood, as does my son at Bedrock Wine Co. We are currently working on a research project using PCR (polymerase Chain Reaction) to see if we can follow the microbiome from the vineyard to the bottle. We should have some preliminary results that will add more color (and perhaps more subtly) to the debate in coming months. Maybe we will affirm Joly, maybe not. Stay tuned. The one absolutey spot on, pragmatic statement here is Blanck’s. Spontaneous fermentation is certainly a less expensive method…and it works well just as often as Cultured yeast.

    • Simon Woolf | The Morning Claret

      Many thanks Joel.

      Your research sounds interesting, although there seems little doubt that wild/spontaneous ferments add complexity and widen the range of flavours and aromas.

      The controversy seems to focus more on terminology and semantics – which I find less interesting than how the finished wine tastes!

      What I find more puzzling is comments like Dwight’s above – which seem to suggest that lettting your must go through a spontaneous fermentation is somehow risky and dangerous – I know so many winemakers (personally, I might add) who would counter this. I am however prepared to accept that it is different depending on the region, and the history of making wine in that area (ie: how well established the indigenous yeast populations are)

      • Tom Mansell
        Tom Mansell

        One thing that can’t be denied is that cultured yeast are more likely to (1) ferment to dryness and (2) do it faster than a spontaneous ferment. Winemakers monitoring tons of tanks and barrels during harvest (and owners with a bottom line in mind) take tremendous comfort in fermentations having successfully completed.

      • Simon Woolf | The Morning Claret


        I quite agree. With large, commercially-oriented wineries there are different considerations at play.

        My quarrel – or at least my puzzlement – is with those winemakers who say things like “it isn’t possible” or “you will get faults in the wine”. These statements are not true – as with all things, it depends on the skill and experience of the winemaker, and the quality of the fruit.

  7. andy

    Unless you’re testing the final wine for what yeasts were present during the ferment, and you actually know what they are via there DNA this all doesn’t matter. If I leave OJ in the fridge long enough it will ferment too… but again, I don’t know what yeast did it.

  8. miles

    I am no commercial winemaker but as a hobbyist I have made wines from grapes and numerous other fruit multiple times and have never had an incomplete fermentation. I just finished fermenting a plum wine of 11% alcohol (No added sugar) without a hitch using wild yeast. The key is simply to have a good starter.

    With time almost all wild ferments will complete either by the adaption of the yeast or the presence of at least one strong strain, as there are literally hundreds present on the skin of every fruit.

  9. Kent Benson

    “It’s (Alsace) the only AOP region in France where the grape variety is permitted to be displayed on the label…”

    If I’m not mistaken, both Bordeaux and Bourgogne AOP wines are permitted to display thier grape variety on the label.