Author Topic: Factors controlling attentuation  (Read 1654 times)

Offline Phil_M

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Factors controlling attentuation
« on: January 18, 2017, 06:01:31 PM »
Besides the obvious grist composition/mash temp/yeast strain, how else can we control attenuation?

Numerous times I've brewed some of Ron Pattinson's recipes, and have ended up with a lower than expected final gravity.

Consider a recent stout I brewed, ended up with a FG of around 1.004, down from an OG of 1.041. Grist used was:

36.4% Irish Stout Malt
14.4% Fawcett Optic Malt
14.4% Golden Promise Malt
  7.6% Rahr 2-row Pale Malt
  8.4% Black Patent Malt
  5.8% Brown Malt
  6.3% Invert No. 1 (Lyle's Golden Syrup)
  6.6% Black Invert (Lyle's Golden Syrup mixed with Blackstrap Molasses)

Yeast was Wyeast 1469, from a shaken not stirred starter. Mash temps were between 152-150 for 90 minutes.

The recipe I based this beer on can be found here:

http://barclayperkins.blogspot.nl/2013/11/lets-brew-wednesday-1923-courage-stout.html

Kristen England's version notes a FG of 1.011, with an apparent attenuation of 74%. I ended up with 90%. FWIW, Wyeast lists the attenuation for this strain as being between 67-71%. I don't see modern malt being the culprit here, as Kristen's version should have had the same issue. Any other ideas?
Corn is a fine adjunct in beer.

And don't buy stale beer.

Offline The Beerery

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Re: Factors controlling attentuation
« Reply #1 on: January 18, 2017, 06:04:22 PM »
Besides the obvious grist composition/mash temp/yeast strain, how else can we control attenuation?

Numerous times I've brewed some of Ron Pattinson's recipes, and have ended up with a lower than expected final gravity.

Consider a recent stout I brewed, ended up with a FG of around 1.004, down from an OG of 1.041. Grist used was:

36.4% Irish Stout Malt
14.4% Fawcett Optic Malt
14.4% Golden Promise Malt
  7.6% Rahr 2-row Pale Malt
  8.4% Black Patent Malt
  5.8% Brown Malt
  6.3% Invert No. 1 (Lyle's Golden Syrup)
  6.6% Black Invert (Lyle's Golden Syrup mixed with Blackstrap Molasses)

Yeast was Wyeast 1469, from a shaken not stirred starter. Mash temps were between 152-150 for 90 minutes.

The recipe I based this beer on can be found here:

http://barclayperkins.blogspot.nl/2013/11/lets-brew-wednesday-1923-courage-stout.html

Kristen England's version notes a FG of 1.011, with an apparent attenuation of 74%. I ended up with 90%. FWIW, Wyeast lists the attenuation for this strain as being between 67-71%. I don't see modern malt being the culprit here, as Kristen's version should have had the same issue. Any other ideas?

Your thermometer is off, or your hydrometer, or both ;)

Offline Phil_M

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Re: Factors controlling attentuation
« Reply #2 on: January 18, 2017, 06:08:53 PM »
Thermometer is a thermapen, and though I suppose it could be off some I rather doubt it. I spot check it on occasion using the manufacturer's outlined procedure. That being said, with no recirculation in my mash tun it's possible that there are "cold spots" that could dry out some of the wort more...but I try and take temp reading all over to avoid this.

I haven't checked my hydrometer in a while though...I'll test it on distilled water when I get home and report back.
Corn is a fine adjunct in beer.

And don't buy stale beer.

Offline blatz

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Re: Factors controlling attentuation
« Reply #3 on: January 18, 2017, 06:09:23 PM »
have you tasted the beer? sounds like could be infection/wild yeast or what Bryan said...
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Offline Phil_M

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Re: Factors controlling attentuation
« Reply #4 on: January 18, 2017, 06:13:16 PM »
have you tasted the beer? sounds like could be infection/wild yeast or what Bryan said...

That was my thought as well, especially since this is a common issue for some of my beers. No infection, nor did it taste unreasonably thin...it was nice and dry. In fact, the IIPA I brewed prior to this beer also had a higher than expected attenuation, and no signs of infection. The IIPA I even shared with several other homebrewers at work, and nobody detected any issues. I even saved a bottle to test a theory on beer shelf life, and after 3 months there were still no signs of infection. (And I learned to always carbonate naturally...)
Corn is a fine adjunct in beer.

And don't buy stale beer.

Offline The Beerery

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Re: Factors controlling attentuation
« Reply #5 on: January 18, 2017, 06:16:13 PM »
Thermometer is a thermapen, and though I suppose it could be off some I rather doubt it. I spot check it on occasion using the manufacturer's outlined procedure. That being said, with no recirculation in my mash tun it's possible that there are "cold spots" that could dry out some of the wort more...but I try and take temp reading all over to avoid this.

I haven't checked my hydrometer in a while though...I'll test it on distilled water when I get home and report back.

2 hours at 154, seems quite excessive, that most likely could be the culprit as well.. You didn't lose any heat over the 2 hours?

Offline HoosierBrew

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Re: Factors controlling attentuation
« Reply #6 on: January 18, 2017, 06:21:27 PM »
Aside from the mentioned possible hydrometer issue,

1/  The mash is too cool and long IMO, especially for basically a session beer where you want some body left in the beer.  45-60 minutes @ 156-158F is my sacc rest for a session ale of that OG.

2/  The 13% total syrups are more fermentable in comparison and would contribute to a lower FG (see Belgian beers) without a high mash temp.


I'm not dissing the recipe - it just seems to lead inevitably to a pretty low FG.
Jon H.

Offline brewinhard

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Re: Factors controlling attentuation
« Reply #7 on: January 19, 2017, 12:17:21 AM »
Aside from the mentioned possible hydrometer issue,

1/  The mash is too cool and long IMO, especially for basically a session beer where you want some body left in the beer.  45-60 minutes @ 156-158F is my sacc rest for a session ale of that OG.

2/  The 13% total syrups are more fermentable in comparison and would contribute to a lower FG (see Belgian beers) without a high mash temp.



This ^^^^^ Especially with regards to #2. Awful high % of simpler sugars for such a low OG>

Offline Phil_M

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Re: Factors controlling attentuation
« Reply #8 on: January 19, 2017, 02:37:52 AM »
Aside from the mentioned possible hydrometer issue,

1/  The mash is too cool and long IMO, especially for basically a session beer where you want some body left in the beer.  45-60 minutes @ 156-158F is my sacc rest for a session ale of that OG.

2/  The 13% total syrups are more fermentable in comparison and would contribute to a lower FG (see Belgian beers) without a high mash temp.


I'm not dissing the recipe - it just seems to lead inevitably to a pretty low FG.

True, but why then the stated FG? Or did Kristen just provide a predicted FG? And why the low FG all malt beer?

And still, way back when the Brits pulled off grists with sugar and ended up with higher FG's...I'm sure some of that is undermodified malts, but I'm wondering what else could be a factor. Perhaps oxygen? I remember Mark mentioning that some strains required aeration at times throughout fermentation...I suppose you may be able to control attenuation that way, but I've never heard of anyone doing so on purpose.
Corn is a fine adjunct in beer.

And don't buy stale beer.

Offline Phil_M

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Re: Factors controlling attentuation
« Reply #9 on: January 19, 2017, 02:49:27 AM »
Checked my hydrometer...0.998 @ 54oF. Beersmith's hydrometer adjustment tool say's that's dead-nuts on.

Got to be the grist, mash temperature, or some outside the box procedural thing.
Corn is a fine adjunct in beer.

And don't buy stale beer.

Offline dmtaylor

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Re: Factors controlling attentuation
« Reply #10 on: January 19, 2017, 05:28:31 AM »
21st century malts are much too well modified for true historical accuracy.  You can try to increase the final gravity in multiple different ways:

1) Try mashing high in the mid 150s for just 30 minutes.  That'd work.

2) Cold crash early, the moment when you hit maybe 3-4 gravity points above your desired end point, to get the yeast settled the heck out of there, and keep it cold, and maybe even add sorbate to hurt them even more.

3) Use Windsor ale yeast instead of whatever else the heck.  Windsor quits at 60-61% attenuation every time guaranteed.

4) Add a buttload of lactose like Kristen himself suggested in the article.

Any or all of the above may give you a more historically accurate taste, even if it might be "cheating".
Dave

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Offline Phil_M

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Re: Factors controlling attentuation
« Reply #11 on: January 19, 2017, 11:31:16 AM »
After having recently discovered I'm lactose intolerant, I will NOT be adding lactose to any future beers.  :P

Mashing high seems the best step to try next. What's the difference between a 30 and 90 minute rest at say 158oF?
Corn is a fine adjunct in beer.

And don't buy stale beer.

Offline HoosierBrew

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Re: Factors controlling attentuation
« Reply #12 on: January 19, 2017, 12:21:14 PM »
After having recently discovered I'm lactose intolerant, I will NOT be adding lactose to any future beers.  :P

Mashing high seems the best step to try next. What's the difference between a 30 and 90 minute rest at say 158oF?


I have no doubt the recipe is good. I just wonder if there was a typo or two. If it were meant to read 'mash 156F for 60 mins', different ballgame. Just a thought.
Jon H.

Offline Phil_M

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Re: Factors controlling attentuation
« Reply #13 on: January 19, 2017, 12:33:52 PM »
I've seen many recipe's on Pattinson's blog that specify strangely low mash temps. My understanding is this is to make sure the beers dry out enough. (And with my experience with low FGs...yes they do)

I remember reading some where about high temp mashes producing wort that isn't fully fermentable, but still dry out nicely if the rest is long enough. Does this ring a bell?
Corn is a fine adjunct in beer.

And don't buy stale beer.

Offline The Beerery

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Re: Factors controlling attentuation
« Reply #14 on: January 19, 2017, 01:57:16 PM »
I've seen many recipe's on Pattinson's blog that specify strangely low mash temps. My understanding is this is to make sure the beers dry out enough. (And with my experience with low FGs...yes they do)

I remember reading some where about high temp mashes producing wort that isn't fully fermentable, but still dry out nicely if the rest is long enough. Does this ring a bell?

I have brewed beers at high mash temps, leading to high FG's to test things. Even a few years back to prove to Denny on facebook Mash temp matters for FG! For me a beer mashed high, will always finish high( but I only make all malt beers), with sugar all bets are off. I can tell you a beer with a FG of 1.016, that was mashed high does not taste like a beer mashed low that was pulled off the yeast early to halt it at 1.016. The first is blah, and the second is sweet. The first doesn't taste sweet, like unfermented sugar sweet, it tastes like a beer that was fermented properly but not crisp, or satisfying.. Blah.