Author Topic: Attenuation surprise  (Read 1581 times)

Offline Kirk

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Attenuation surprise
« on: March 13, 2011, 06:06:06 PM »
Wyeast 1272 American Ale yeast ll-Flocc High-72-76% atten.
     Results:  FG 1.011  82% atten. ABV 6.9%
Wyeast 1332 Northwest Ale yeast-Flocc High-67-71% atten.
     Results:  FG 1.010  84% atten. ABV 7.0%

AIPA, 22.6 lbs of grain, 10 gallon batch, 1.064 OG, split in half for the above yeasts.
That's only about 11 lbs of grain for a 5 gallon batch of 7 percent beer.  The Northwest Ale finished drier than the American II and it's not supposed to be a real dry one.
I'm wondering what I did right to get attenuation rates so far above advertised levels.  Was it the Hockburz two-step?  It was in primary for just over three weeks.  No fusels.  No off flavors.
I'm not complaining, it's just going to kick some ass. ;)
Kirk Howell

Offline a10t2

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Re: Attenuation surprise
« Reply #1 on: March 13, 2011, 06:26:04 PM »
What was the mash schedule like? Did you calibrate your thermometer recently? I've never used 1332, but 1272 will routinely hit >80% ADF.
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Offline Kirk

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Re: Attenuation surprise
« Reply #2 on: March 13, 2011, 06:40:24 PM »
You mean hydrometer right?  It's a finishing hydrometer, so I'm real confident in it, but I will calibrate it right now.
Mashing?  100, 125, 145, 158, 170.  Yes, a long rest at 145 and 158.
It's calibrating right on 1.000.
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Offline a10t2

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Re: Attenuation surprise
« Reply #3 on: March 13, 2011, 06:50:30 PM »
I meant thermometer, in case you were resting at lower temperatures than you planned, but with that mash schedule I'm actually surprised your attenuation is so *low*. You're doing everything you can to make a highly fermentable wort.
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Offline Kirk

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Re: Attenuation surprise
« Reply #4 on: March 13, 2011, 07:01:36 PM »
Given.  So, the percentages they list are just mid-range averages?  And not outside limits?
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Offline beersk

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Re: Attenuation surprise
« Reply #5 on: March 14, 2011, 07:45:49 AM »
Yeah, you're mashing pretty low for your sac rest, which will give you that high attenuation.  I've actually been getting quite annoyed at the high attenuation I've been getting.  I'd rather have the beer finish around 1.015 instead of 1.010 for a medium to full bodied beer.  The higher attenuation tends to make the beer a little more one dimensional.  So I've been trying to mash in the upper 150s to see how it affects it.
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Re: Attenuation surprise
« Reply #6 on: March 14, 2011, 08:31:56 AM »
Given.  So, the percentages they list are just mid-range averages?  And not outside limits?

Neither...they're simply a way of comparing one to another.  They have little bearing on the attenuation you'll actually get.  And the fact that you're comparing 2 separate batches rather than splitting one batch of wort to compare lends more variables.
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Offline maxieboy

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Re: Attenuation surprise
« Reply #7 on: March 14, 2011, 10:15:38 AM »
Ahem.   ;D

AIPA, 22.6 lbs of grain, 10 gallon batch, 1.064 OG, split in half for the above yeasts.
That's only about 11 lbs of grain for a 5 gallon batch of 7 percent beer.  The Northwest Ale finished drier than the American II and it's not supposed to be a real dry one.
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Offline denny

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Re: Attenuation surprise
« Reply #8 on: March 14, 2011, 10:16:31 AM »
Ahem.

AIPA, 22.6 lbs of grain, 10 gallon batch, 1.064 OG, split in half for the above yeasts.
That's only about 11 lbs of grain for a 5 gallon batch of 7 percent beer.  The Northwest Ale finished drier than the American II and it's not supposed to be a real dry one.

DOH!  More coffee!  Thanks.....
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Offline Kirk

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Re: Attenuation surprise
« Reply #9 on: March 14, 2011, 10:55:36 AM »
Neither...they're simply a way of comparing one to another.  They have little bearing on the attenuation you'll actually get.

So, the numbers are only relative to each other, one more or less attenuative than the rest of the field.  That makes sense.
But that Northwest Ale yeast finished drier than the A2, and it's numbers are lower.  It did take longer to drop, though.  The A2 was clearing after a week, but the NW stayed in suspension for 2 1/2 weeks.
Kirk Howell

Offline tschmidlin

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Re: Attenuation surprise
« Reply #10 on: March 14, 2011, 11:06:30 AM »
The numbers are what they got with a specific wort under set conditions, and they might have only done it once to measure it.  It's informative, but as you're finding out, it's not set in stone.
Tom Schmidlin

Offline Kirk

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Re: Attenuation surprise
« Reply #11 on: March 14, 2011, 11:36:04 AM »
Thanks guys, I am finding that out.  I'll have to pay more attention to hitting my target FG.
Kirk Howell

Offline bluesman

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Re: Attenuation surprise
« Reply #12 on: March 14, 2011, 11:43:57 AM »
Thanks guys, I am finding that out.  I'll have to pay more attention to hitting my target FG.

One thing to keep in mind is that different yeasts work in different ways but are somewhat adaptable. I find that certain yeasts outperform the lab specs and therefore have to be tweaked to achieve specific results. In your case you may want to tweak the mash schedule to lower the attenuation as was stated.

The main considerations to healthy fermentation are calculated pitching rates and proper oxygenation. Then attenuation can be tweaked to your liking.
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Offline Kirk

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Re: Attenuation surprise
« Reply #13 on: March 15, 2011, 07:23:23 PM »
Thanks for the input everyone.  I've been thinking about three new firsts (for me) in this batch that may also have had an impact:  I brought up the magnesium level in the water build, and to the boil I added yeast nutrient and zinc.  I'll probably keep doing that from now on, so there's more reasons to pay closer attention to mash temperatures and schedules.
Kirk Howell

Offline tom

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Re: Attenuation surprise
« Reply #14 on: March 15, 2011, 08:44:37 PM »
Any sugars in your recipe? They are very fermentable and will increase your overall attenuation.
What was your fermentation temperature? Higher fermentation temperatures will help the yeast ferment more completely.
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