Yeast attenuation and alcohol tolerance

[RNBEERGUY]

Is there a direct correlation between yeast attenuation and ethanol tolerance ? Asking out of curiosity

 

[cactusgarrett]

Absolutely. The higher the ABV, the less efficient and healthy the yeast are. Pretty much every yeast strains will have a given alcohol tolerance (expressed in percentage) under "typical" wort conditions and acceptable pitch rate. Once this tolerance is exceeded, you'll start to see stalled fermentation and higher FGs.

For example (using generalities and typicalities here), Wyeast claims their 1056 strain has an attenuation of 73-77% (let's assign 75%) and an alcohol tolerance of 11%. If you brew something big and use 1056, if your beer has the potential to go beyond 11%, once you reach that 11%, you could only get 70% attenuation and stall in your fermentation.

Here's a good position.

 

[Pappers_]

+1 to the above. But there are many other factors that impact attenuation, also. Mash temp, yeast strain, grain bill, fermentation temperature, pitch rate, yeast vitality, etc.

Your question is more complicated than it might appear at first.

 

[kh54s10]

There could be instances where the correlation doesn't apply. If you brew a low gravity beer with a yeast that tollerates high alcohol content, you won't get to the point where the alcohol will affect the attenuation. And if you brew a high alcohol beer with a yeast that easily handles the alcohol it will also not affect the attenuation.

 

[Pappers_]

There could be instances where the correlation doesn't apply. If you brew a low gravity beer with a yeast that tollerates high alcohol content, you won't get to the point where the alcohol will affect the attenuation. And if you brew a high alcohol beer with a yeast that easily handles the alcohol it will also not affect the attenuation.

That's what I was trying to say, but you said it in a much clearer way. Thanks!

 

[Northern_Brewer]

It obviously makes sense for the two to be correlated and selected for together, but there's not a direct link. For instance the Guinness and McEwans strains have typical British attenuation but are relatively alcohol-tolerant, but there's plenty of relatively attenuating British strains which have "typical British" alcohol tolerance, like Bedford and East Midlands as well as a lot of lager strains.

 

[RNBEERGUY]

Absolutely. The higher the ABV, the less efficient and healthy the yeast are. Pretty much every yeast strains will have a given alcohol tolerance (expressed in percentage) under "typical" wort conditions and acceptable pitch rate. Once this tolerance is exceeded, you'll start to see stalled fermentation and higher FGs.

For example (using generalities and typicalities here), Wyeast claims their 1056 strain has an attenuation of 73-77% (let's assign 75%) and an alcohol tolerance of 11%. If you brew something big and use 1056, if your beer has the potential to go beyond 11%, once you reach that 11%, you could only get 70% attenuation and stall in your fermentation.

Here's a good position.

Thanks for the great response one more question is attenuation only refering to fermentable sugar or all sugar

 

[kh54s10]

Attenuation is how far from OG a yeast can ferment a wort in percentage. If you have a 1.090 beer and use a yeast with a 78% attenuation rate you can expect the FG to be reduced 78% from the OG.
Fermentable sugars will be "eaten" by the yeast and will produce alcohol. Unfermentable sugars are just that. The yeast will not be able to "eat" these so they leave the beer with sweetness.

Here is a calculator that will give you ABV and below apparent attenuation: https://www.brewersfriend.com/abv-calculator/

Here is an article, I didn't read it but it probably has all your answers: https://www.whitelabs.com/resources/attenuation-and-flocculation

 

[cactusgarrett]

Just what kh54s10 said. Generally speaking, the attenuation assigned to a strain is a moving target. If you've got more fermentable sugars (short chain) available in the wort, you're going to get better attenuation than what's claimed by the manufacturer. For example, (yeast health/nutrition aside), if you have just a solution of corn sugar in water, WY1056 will undoubtedly take that down WELL beyond it's assigned 75% expected attenuation. Conversely, a wort comprised of 100% cara-pils will undoubtedly see an attenuation WELL below 75%.

This is what I was referring to in my original post when I mentioned ""typical" wort conditions and acceptable pitch rate".