Yeast alcohol tolerance accuracy

[taleman]

How accurate are the tolerance levels of different yeasts? For example Lavlin D47 is supposed to have a tolerance if 14%. Does that mean that 100 % of the time it will not ferment beyond 14% alcohol?

Also what happens at 14%. Does it kill the yeast? Or does the yeast simple stop fermenting but then if you add water lowering the potential alcohol it resumes (assuming there is still sugar)?

 

[Brewmasher]

Most labs test their yeast using 100% malt wort at the low end of the temp range. I found most specs to be conservative. If the yeast is healthy, I would expect it to ferment at least a few points higher. When alcohol levels reach the tolerant threshold of the yeast, it will die, or become severely weakened.

 

[taleman]

Most labs test their yeast using 100% malt wort at the low end of the temp range. I found most specs to be conservative. If the yeast is healthy, I would expect it to ferment at least a few points higher. When alcohol levels reach the tolerant threshold of the yeast, it will die, or become severely weakened.

thanks, so if I took it up to 18% that would definitely kill the yeast and prevent further fermentation. Or do you think I would need to go higher to be 100% sure.

 

[day_trippr]

thanks, so if I took it up to 18% that would definitely kill the yeast and prevent further fermentation. Or do you think I would need to go higher to be 100% sure.

Um, what are you thinking about doing, exactly?
Dosing your brew with a couple quarts of white lightning?

Cheers!

 

[Yooper]

I think they report an average alcohol tolerance, but it definitely does not reliably stop at a given ABV.

I've seen champagne yeast successfully pushed to well over 18%, as an example. The idea there was to end up with a sweet wine, without stabilizing. The yeast would be overwhelmed, and then there would be residual sugar left for a sweet wine.

Well, the yeast loved that extra sugar and kept chugging along, leaving a "hot" sweet rocket fuel at about 19.5% ABV behind.

So, I wouldn't use it as a given that it would stop at a certain ABV, however it very well could stop about where the yeast company said it would. Or not. In general, D47 will probably stop before EC-1118. But not reliably so, and not enough to depend on it.

 

[ChelisHubby]

I think they report an average alcohol tolerance, but it definitely does not reliably stop at a given ABV.

I've seen champagne yeast successfully pushed to well over 18%, as an example. The idea there was to end up with a sweet wine, without stabilizing. The yeast would be overwhelmed, and then there would be residual sugar left for a sweet wine.

Well, the yeast loved that extra sugar and kept chugging along, leaving a "hot" sweet rocket fuel at about 19.5% ABV behind.

So, I wouldn't use it as a given that it would stop at a certain ABV, however it very well could stop about where the yeast company said it would. Or not. In general, D47 will probably stop before EC-1118. But not reliably so, and not enough to depend on it.

SO I guess you would have to back sweeten a wine to keep it from being very dry reliably.!

 

[Brewmasher]

If you're trying to kill the yeast, I suppose poisoning them with alcohol would work, but there are other options.

The only reason I can think of why anyone would do that is to back sweeten the beer. The only reason why you would have to is because you used the wrong strain that attenuates dry instead of sweet. You can always sweeten beer with lactose, which is not fermented by typical brewers yeast. Or you can just add a little simple syrup before consuming.

You could use sorbate, or pasteurize the beer. These practices are not common in brewing, but are in wine, mead and cider making.