Yeast alcohol tolerance question

Oswaldo Costa

Oswaldo Costa
Last night, without too much stress I survived a bottle of 2007 Dettori Chimbanta 17.5% split three ways, but was wondering how can saccharomyces cerevisiae survive up to/at this level? One would imagine that some designer yeasts could do the trick, but natural ones? (unless the indigenous are descendants of more alcohol tolerant inoculants used in the past)
 
I remember reading books when I was a wee tot that more or less claimed that yeast couldn't push past 14% or so. I think this is also the origin of the US tax system (correct me, ITB mavens), where wines above 14 are taxed at a higher rate since they are presumed to be fortified.

But clearly there are a lot of yeast in the world that can finish, or nearly finish, wines at much higher abv. Some are the cultured survivors of high brix ferments (I think Turley was the source of one of these), and sometimes the little buggers will just surprise you.

But I would hear more from the experts.
 
A quick google search shows some articles claiming a max of 15%, others of 17%, but none as high as 17.5%, if it's not being too persnickety to harp on the extra 0.5%.
 
Turley seems to have reached 17.5% in the past without fortification.

The max level will depend on other things--how much rs remains, other nutrients, etc.

But a great question for Clark Smith!

Perhaps they watered back and then concetrated with R/O?
 
Impressive. GMO yeasts can probably go up the wazoo, but I always figured the humble, tree-hugging, vin nature yeast to be something of a wimp.
 
originally posted by Oswaldo Costa:
Impressive. GMO yeasts can probably go up the wazoo, but I always figured the humble, tree-hugging, vin nature yeast to be something of a wimp.

Let us not diminish the potential of natural or directed selection on natural diversity.

Chihuahuas used to be wolves, after all.
 
Keep in mind, O., that those "designer" yeasts are not the products of careful genetic manipulation in a lab. They are just strains of yeast that, through natural (or artificial, if you will) selection, have been "optimized" for a certain trait (ester production, alcohol tolerance, whatever). So, if a strain of yeast exists that can tolerate 17.5%, it stands to reason that it can also be present in a "native" population, which means that it can be naturally selected for during fermentation. I can recall some freakazoid "late harvest" Zins from the '70s that went Northward of 15% (and still didn't ferment dry), and those wines never saw a designer yeast, that I can tell you.

Mark Lipton
 
Gotcha. So if Dettori is to be believed, and one presumes so, then there has to be a strain of saccharomyces in his neck of the Sardinian woods that can stand 17,5%. Folks in the Congo should be harvesting it.
 
Mark is right--when that 18% fermentation was finishing up, the winery team all gave them a round of applause and then grabbed some of the yeast out of the vat and made a pure culture of it. Which can be propagated and sold in little foil packets in a grocery story or winery supply house near you.
 
I like to imagine that the little yeasts took a bow after receiving the applause for their legendary performance. Curtain call and everything.
 
Hmm, let's see, smelled of alcohol, acetone and model airplane glue. But not unpleasant, even a little enjoyable. At first sip, the alcohol burned the throat, acting like a powerful disinfectant. Good for those with a cold, says Marcia (my wife). Difficult to say whether it lacks acidity when the burning alcohol plays an analogous astringent role and obliterates everything in its path. I thought the acidity might be lacking, but Marcia didn't. It was an unusual experience (for which I am always thankful) because it was alcoholic and viscous without seeming supermature or superextracted. The lack of wood further avoided similarities with commonplace high octane supershit. Reminiscent of amarone, no doubt. Like a southern amarone, without the ripasso. It certainly not my cuppa, but after the initial sting, it did not seem like I was being whipped. I guess it was interesting, with all the ambiguity of that overabused word.

Anyway, it's great that the wine is what the wine wants to be, and not what the market wants it to be, but it begged the question (in the incorrect sense of the phrase) of why choose to make natural wines in latitudes so sizzling that it is unlikely to be acid/sweet balanced without correction. A Don Quixote Complex? A Just Because I Want To Complex? A Duh, Because I Am From Here Complex? A There Are People Who Like Southern Amarones Without Ripasso So Fuck Off Complex? Hard to tell.
 
Diploid yeast can double every 100 minutes and has a 26 replications span. With generational changeover this fast, natural selection could produce yeast with the capacity to survive higher alcohol levels fairly consistently and quickly I suspect. And certainly, they are happily producing 16% and higher in the Southern Rhone (which is not to say I am happy about it).
 
originally posted by Oswaldo Costa:


Anyway, it's great that the wine is what the wine wants to be, and not what the market wants it to be, but it begged the question (in the incorrect sense of the phrase) of why choose to make natural wines in latitudes so sizzling that it is unlikely to be acid/sweet balanced without correction. A Don Quixote Complex? A Just Because I Want To Complex? A Duh, Because I Am From Here Complex? A There Are People Who Like Southern Amarones Without Ripasso So Fuck Off Complex? Hard to tell.

I am not sure the latitude's the problem, there are lots of very good wines being made in e.g. Campania that aren't high-octane. (Some of them are lower than wines from classic regions in N. Italy.) I think it's a human problem, like it is in CA; it's just that the average producer picking at that Brix level would de-alcoholise, and Dettori is 'natural,' so of course they don't stoop so low.
 
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