Author Topic: Over Attenuation?  (Read 1909 times)

Offline In The Sand

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Over Attenuation?
« on: May 22, 2013, 06:00:15 PM »
So a buddy and I were having a conversation about final gravity. I have several recipes that have finished below 1.010. Around 1.005-1.008 to be exact. He mentioned getting that low usually means wild yeast was introduced somewhere. I've only been brewing for a year and typically US-05 is my go-to yeast. What do you think of this hypothesis? 
Trey W.

Offline a10t2

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Re: Over Attenuation?
« Reply #1 on: May 22, 2013, 06:04:37 PM »
A lower than expected final gravity could be evidence of contamination. You can't just arbitrarily pick a number and apply it to all beers though. Fermentability depends on the mash parameters. Yeast strain can also influence FG to a lesser extent, and Chico is one of the most attenuative strains there is. As a general rule, low flocculation means high attenuation.
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Offline denny

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Over Attenuation?
« Reply #2 on: May 22, 2013, 06:34:58 PM »
So a buddy and I were having a conversation about final gravity. I have several recipes that have finished below 1.010. Around 1.005-1.008 to be exact. He mentioned getting that low usually means wild yeast was introduced somewhere. I've only been brewing for a year and typically US-05 is my go-to yeast. What do you think of this hypothesis?

I think it's completely off the mark unless the beers taste like they're infected.
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Offline erockrph

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Re: Over Attenuation?
« Reply #3 on: May 23, 2013, 05:52:21 AM »
So a buddy and I were having a conversation about final gravity. I have several recipes that have finished below 1.010. Around 1.005-1.008 to be exact. He mentioned getting that low usually means wild yeast was introduced somewhere. I've only been brewing for a year and typically US-05 is my go-to yeast. What do you think of this hypothesis?

I think it's completely off the mark unless the beers taste like they're infected.

+1 - much more likely is a hydrometer that isn't calibrated properly, or not adjusting for temp or something along those lines. If the beer doesn't taste infected and you aren't getting gushers or anything like that, then I doubt it is an infection.
Eric B.

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Offline bwana

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Re: Over Attenuation?
« Reply #4 on: May 23, 2013, 05:58:32 AM »
I was shocked when one of my beers finished at 1.004. I had this beer around for a long tome. Tasted great.

Offline HoosierBrew

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Re: Over Attenuation?
« Reply #5 on: May 23, 2013, 06:14:40 AM »
A thermometer that's not calibrated properly could easily let you mash a good bit lower than you wanted, creating a much more fermentable wort.  Also, styles come into play.  My recent saison was mashed @ 147, finished @ 1.002.  No infection there whatsoever.
Jon H.

Offline In The Sand

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Over Attenuation?
« Reply #6 on: May 23, 2013, 08:23:38 AM »
So a buddy and I were having a conversation about final gravity. I have several recipes that have finished below 1.010. Around 1.005-1.008 to be exact. He mentioned getting that low usually means wild yeast was introduced somewhere. I've only been brewing for a year and typically US-05 is my go-to yeast. What do you think of this hypothesis?

I think it's completely off the mark unless the beers taste like they're infected.

You mean the infection hypothesis is not likely?

He has been brewing for at least 5 years and said he's never had a beer finish below 1.010. Also, I use a digital thermometer and recently checked my hydrometer for calibration.

None of these beers tasted infected. One pale ale was a bit fruitier than expected when using US-05, but that was later attributed to hops selection.
Trey W.

Offline denny

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Re: Over Attenuation?
« Reply #7 on: May 23, 2013, 09:47:05 AM »
You mean the infection hypothesis is not likely?

He has been brewing for at least 5 years and said he's never had a beer finish below 1.010. Also, I use a digital thermometer and recently checked my hydrometer for calibration.

None of these beers tasted infected. One pale ale was a bit fruitier than expected when using US-05, but that was later attributed to hops selection.

I'd go as far as to say it's highly unlikely.

I've been brewing for 15 years and 437 batches.  US 05 is a highly attenuative yeast.  I've had many beers finish below 1.010 with 05 and other yeasts.    Just because your friend hasn't doesn't man your beer is infected.  Especially since it doesn't taste like it.

BTW, just because it's a digital thermometer doesn't necessarily mean it's accurate.
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Offline bluesman

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Re: Over Attenuation?
« Reply #8 on: May 23, 2013, 09:58:00 AM »
I agree with Denny here.

As has been said, it really depends on you mashing regime, yeast viability/strain, fermentation health and recipe formulation to name a few. Using a calibrated hydrometer  and thermometer are recommended here. I wouldn't rush to judgement on any one variable, but look a the big picture, then break down your process variables piece by piece. Start with your recipe first, then look at your mash schedule, then calibration steps, and so forth.
Ron Price

Offline In The Sand

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Over Attenuation?
« Reply #9 on: May 23, 2013, 10:51:22 AM »
Thanks guys for the input.
Trey W.

Offline skyler

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Re: Over Attenuation?
« Reply #10 on: May 24, 2013, 12:30:35 PM »
I have always enjoyed using lab thermometers because they are easy and cheap and usually very accurate. Until I had one recently that measured temperatures off by 4º F. That is, when it read 148º, I was actually mashing at 154º. Every beer was sweeter than I wanted, until I forgot my thermometer and used a backup kitchen thermometer, then used a friend's thermometer... The moral of a story is that thermometers can be inaccurate, even the ones that are "laboratory grade."

Also, I regularly get 80-84% attenuation with US-05. A 1.008 finish is a common occurrence for me with any of the Chico strains.

Offline yso191

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Re: Over Attenuation?
« Reply #11 on: May 24, 2013, 02:34:13 PM »
I've been wondering about this because my beers ALLWAYS finish 3-5 points lower than what Beersmith predicts.  Almost always below 1.010, and occasionally as low as 1.003.  I've never had an infection, and it hasn't been a problem, I just get a higher ABV than planned.  Now I just make a mental adjustment when I see Beersmith's prediction.
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Offline a10t2

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Re: Over Attenuation?
« Reply #12 on: May 24, 2013, 03:08:13 PM »
Now I just make a mental adjustment when I see Beersmith's prediction.

FWIW, BeerSmith isn't predicting anything. It's just using the attenuation numbers from the yeast labs. You can change the predicted attenuation to match what you actually get, if you want. http://www.beersmith.com/help2/index.html?yeast.htm
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Offline The Professor

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Re: Over Attenuation?
« Reply #13 on: May 24, 2013, 03:11:44 PM »
So a buddy and I were having a conversation about final gravity. I have several recipes that have finished below 1.010. Around 1.005-1.008 to be exact. He mentioned getting that low usually means wild yeast was introduced somewhere. I've only been brewing for a year and typically US-05 is my go-to yeast. What do you think of this hypothesis?

I think it's completely off the mark unless the beers taste like they're infected.

Totally agree. As a rule I don't like my beers to finish below 1.015 or so, but if they do, I don't give it a second thought if the taste I want is there.
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Offline ynotbrusum

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Re: Over Attenuation?
« Reply #14 on: May 30, 2013, 07:10:41 PM »
I used to rely on my Blichmann dial thermometer for temperatures, but found it unreliable when confirmed with a Thermapen - sometimes 6-8 degrees off, so my mash temps were off and I had highly fermentable worts that finished down around 1.006 or so routinely.  Now with the Thermapen, I am hitting my temps/ adjusting my temps more accurately and 1.010 OG is reached much more frequently on my beers the days.
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