Author Topic: Attenuation Percentage  (Read 2959 times)

KellerBrauer

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Attenuation Percentage
« on: January 10, 2018, 04:49:12 PM »
Greetings All - Is there a correlation between ?Attenuation Percentage? and ?Temperature Range??  In other words, when looking at a yeast strain, there is a specification for Attenuation, for example: 70-74% and a temperature range of, for example: 65 and 73 degrees F.  Can one assume that at 65 degrees F one can get 70% attenuation and at 73 degrees one would get 74%?

The thought process is based on yeast being more active at higher temperatures.  Hence, higher attenuation??? 
« Last Edit: January 10, 2018, 04:51:40 PM by KellerBrauer »

Offline BOB357

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Re: Attenuation Percentage
« Reply #1 on: January 10, 2018, 05:50:35 PM »
Never really thought much about that correlation but, since you bring it up, I have brewed with Chico strains, Nottingham and a couple of others at different temperatures and never related fermentation temperature to attenuation.

Might be something to keep better track of in the future. Just off the top of my head, If it does relate I would think it to be a minor player when compared to yeast health, pitching rate, oxygenation, grist composition and mash temperature as it relates to wort fermentability. Sounds like another factor to track as we try to constantly dial in our processes.
Bob

KellerBrauer

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Re: Attenuation Percentage
« Reply #2 on: January 11, 2018, 05:18:53 AM »
Greetings Bob and thanks for your input.  I realize that yeast heath, pitch rate, oxygenation, etc., have elverything to do with fermentation.  But the thought came to me the other day while formulating a recipe for a vanilla porter, whether the two specification ranges (attenuation and temperature) are in some way related.

I recently read the book: Yeast, a Practical Guide to Yeast Fermentation, by Chris White and I recall no mention of a correlation between the two.  So perhaps the lack of language on this subject is the answer to my question.  But, at the same time, I think there will be a higher level of attenuation at a higher temperature.  Hmmmmm.....

Thanks again for your input Bob!

Offline Oginme

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Re: Attenuation Percentage
« Reply #3 on: January 11, 2018, 08:18:15 AM »
From my experience with a couple of yeast strains that I have worked with extensively: WY1028 (London Ale) and WY1272 (American Ale II), I have not been able to correlate an apparent attenuation with the fermentation temperature as much as residual yeast flavors.  WY1028 throws more esters and leads to more maltiness at higher temperatures (68?F to 70?F) versus lower fermentation temps (64?F to 66?F).  WY1272 is pretty clean at fermentation temps below 66?F and above 70?F gives me some nice fruity esters.  Beyond that, I don't see much variation from actual FG versus target regardless of fermentation temp.
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Offline Kevin58

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Re: Attenuation Percentage
« Reply #4 on: January 11, 2018, 08:28:28 AM »
I just read an article about a brewery in England that intentionally kept attenuation low on some of their beers and they did it, in part, by fermenting at lower temperatures.
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Offline brewfun

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Re: Attenuation Percentage
« Reply #5 on: January 11, 2018, 08:54:29 AM »
There is no correlation between increased fermentation temperature and attenuation in ideal circumstances. "Ideal" being pure Saccharomyces, proper nutrients and oxygenation, plus appropriate alcohol tolerance. Basic beer yeasts do not create enzymes to break down complex starches or sugars, so there isn't any mechanism to increase attenuation.

Increased temperature can mask wort deficiencies by simply keeping the yeast more active, though this typically results in artifacts like esters, sulfur, acetaldehyde and fusel alcohols.

However, in mixed cultures or contamination, all bets are off. In these cases, temperature can indeed increase attenuation because these organisms may produce the enzymes required.
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KellerBrauer

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Re: Attenuation Percentage
« Reply #6 on: January 11, 2018, 04:53:53 PM »
Greetings All - thank you for your responses. They all make perfect sense. Something told me there was no correlation, but I needed that explanation.

Thanks again!!

Offline Oginme

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Re: Attenuation Percentage
« Reply #7 on: January 11, 2018, 05:14:50 PM »
I just read an article about a brewery in England that intentionally kept attenuation low on some of their beers and they did it, in part, by fermenting at lower temperatures.

I have heard of brewers doing just that, but they are affecting the attenuation by lowering the temperature to a point where the yeast starts to flocculate and settle out rather than allowing the fermentation to complete.
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