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StevenC

How would you tell if natural yeast or commercial yeast was used?

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I was reading Alice Feiring's book, "Naked Wine," where towards the beginning she's drinking a wine from Sonoma and asks the winemaker why he used commercial yeast in it when he said he had switched (as it turned out, in later vintages) to natural yeast.

How would you tell that a winemaker used commercial yeast as opposed to relying on natural/indigenous/ambient yeast?

I'm guessing the following might be signs, but are there any others?

Natural yeast: higher volatile acidity, funkier aromas from more diverse yeasts, maybe less exuberant fruit

Commercial yeast: less volatile acidity, absence of funky aromas, maybe higher alcohol level, maybe some surprising fruit aromas for the variety/region (for example, banana in Beaujolais, yellow apple in Muscadet, and so forth)

I'd assume, however, that many of these things could also be due to other reasons...

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From what i've learned, you can't. Commercial yeasts have been manufactured with a lot of these sensory potentials in mind - for example you can have a yeast strain that is sure to be produce more aromatics that can be 'fruity' or 'vegetal', whilst other yeasts are designed to withstand high alcohol levels.

As intriguing as natural and wild fermentations are, I think a majority of the time, it's a bit of a wate as the potential of the wine to be great isn't as high as if you knew what you were looking for.

And yes, many other factors also determine all the other sensory aspects.

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How would you tell that a winemaker used commercial yeast as opposed to relying on natural/indigenous/ambient yeast?

Me, for sure I am not able to tell (I know, 'cause I've tried) :D

I would mainly guess though that commercial yeast provides an improved consistency in the palette. It will certainly partially come down to what one is looking for, consistency between years, bottles etc., or the unique taste of a specific year, vineyard etc. I do have some impression, however, that there's a certain amount of marketing strategy and spin in the 'natural yeast' movement.

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Commercial yeasts have been manufactured with a lot of these sensory potentials in mind

Actually, commercial yeasts are simply propagated from harvests of natural, indigenous yeasts. They are not "manufactured" to create certain elements in a wine. And some yeast packages are 'blends', sort of like teas. Specific yeasts - which already exist in nature - are already known to have certain qualities ... some boost floral aromas, some bring out the spice, some support darker pigmentation. It is true that they are grown and packaged in a laboratory setting, but that is done to keep the strains pure, viable, and to be able to grow them in commercial quantities.

Think of it as a nursery, growing cuttings of roses and raising seedlings for your garden.

To answer the original question ... no, you can't tell. From the yeast alone, that is. However, Alices' penchant for 'natural' winemaking means a lot of the wines she recommends are also high in brettanomyces infections, suffer from imbalanced acidity, and other factors that have nothing to do with the yeast. She's a sucker for caves dripping with dank moss and fungus (also getting into the corks), and vineyards with thigh high weeds and thistles.


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I just finished my sommelier training, and during that time we tasted some 300 wines. In quite a few instances I asked our lecturer: "Has this been fermented with wild yeast?" In each instance it had. What does this mean? Can I taste (or smell) wild yeast?

The short answer is "no".

What I noted was the same "funky" aromas that lambic(*) are famous for, the same aromas the come from brettanomyces. What I smelled was, in my opinion, poorly made wines. As it turns out I'm particularly sensitive to brettanomyces(**), which has led me to a few discussions with some of the natural wines fans.

Brettanomyces comes from the skin of the grapes and develop much more easily in natural wines for two reasons:

1. The cultivated yeasts that most wine producers use (natural wines is still a very small niche in a niche (biodynamic wine)) overpower brett and thus makes sure it never develops.

2. The low to none sulfur additions that are also part of natural wines also aids brettanomyces as the sulfur, being an anti-oxidant, would inhibit brettanomyces growth.

Wild yeasts, as has been mentioned, are the yeasts that later have been cultivated so that one can choose which properties one wants the most. Also, a wine maker in Austria once told me that lab tests show that wild yeasts will eventually, during fermentation, develop into the same yeast strains as the cultivated ones, and that they are 70% identical. The difference isn't that big, according to him (he's a biodynamic producer, but not a natural wine producer), but he preferred the predictability of the cultural yeasts.

Also; a lot of cultured yeasts are cultured from yeasts strains from that area, meaning that they do originate from the same terroir as the wild yeasts would.

(*) Lambic are the wheat beers from Belgium, named after the town Lambeek, that are yeasted with wild yeast.

(**) Fascinatingly enough we all have different levels of sensitivity to different aromas. For example the studies that are being done by Centro de Aromas show that the difference in sensitivity to rotundon (which is the smell of black pepper often found in shiraz/syrah) varies a lot. Some people can detect levels as low as 0,000000016 nanograms per litre and others still can't pick it up at 4000 nanograms per litre (one in five, in their tests, actually). I am not sensitive to pepper, rather below average, but very sensitive to brett and about average on TCA. We are all different, which makes smelling wine both fascinating and frustrating.

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Just to add onto the brett conversation, the other source of contamination particularly in the views of a lot of new world producers, it can come via not cleaning your equipment, mainly barrels.

What is considered natural wine by the way? I know in the US there are very specific regulations for organic wines, but nothing called natural.

I think you could also argue that wines with high alcohol contents would lean more towards manufactured yeast. I believe that a lot of wild yeast strains are not able to get up to too high of a alcohol level, especially if the grapes were harvested somewhere in the ball park region of 25 brix and onwards.

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So a multipart answer:

Steven,

It's very very hard. There are no red flags that you're dealing with spontaneous fermentation vs. cultured yeast. Given all the points of intervention in the winemaking process, being able to pick out what aromas, flavors and textures come from one way or the other is really difficult, even if you're in a tightly controlled situation (say, tasting Mosel Riesling - some of which are spontis and some of which are not).

Piracer,

I'm trying to parse your statement: "I think a majority of the time, it's a bit of a wate (sic) as the potential of the wine to be great isn't as high as if you knew what you were looking for." Are you saying that spontaneously fermented wines can't reach the same heights as cultured-yeast fermented ones? I'd think that people like Joly, J.J. Prum and Nikolaihof-Wachau would disagree with you.

There are great sponti wines and great Wyeast fermented wines. There are poor examples of them as well. Blaming the yeast is like blaming the barrel for a bad (or good) wine. It might be part of the story, but it's never all of it.

Mary,

Ooh... an ad hominem argument. Are you claiming that winemakers who use cultured yeasts never suffer from brettanomyces or imbalanced acidity, or is there another reason you don't like spontaneously fermented wines? "Natural" (sic) winemaking is a moving target that's not well defined. Blaming the yeast selection as the primary cause of wine quality ignores the other thousands of decisions a winemakers chooses in any given day.

Thanks,

Zachary

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Ah no, i'm not saying anything about the quality of the wine. I said that a lot of the cultivated strains of yeast were often done so in mind towards high alcohol wines.

By no means should yeast be the sole reason for poor quality, but it can certainly be part of the reasons as to why its bad.

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Mary,

Mary,

Ooh... an ad hominem argument. Are you claiming that winemakers who use cultured yeasts never suffer from brettanomyces or imbalanced acidity, or is there another reason you don't like spontaneously fermented wines? "Natural" (sic) winemaking is a moving target that's not well defined. Blaming the yeast selection as the primary cause of wine quality ignores the other thousands of decisions a winemakers chooses in any given day.

What are you smoking? I have no problem with natural fermentations, have made one release of my own and the winery where I was a partner for 10 years has had multiple releases of natural or partially spontaneous fermentations. I was pointing out, for those who are interested in learning more about commercial yeasts, that they are not lab creations but isolated and propagated native yeasts chosen for their unique properties.

I do object to Feiring's rather simplistic, only-old-world-is-good "Green Acres" approach to wine. As can be seen in my interview with her here: http://cellarrats.proboards.com/thread/150 where we spar a little over yeasts and amendments.


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Mary Baker

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