Author Topic: 10 point FG difference  (Read 2512 times)

Offline dmtaylor

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Re: 10 point FG difference
« Reply #15 on: November 25, 2015, 09:04:30 am »
I have had success in the past with unsticking stuck fermentations using yeast energizer and warmth, and lots of swirling.  I usually run into this problem with finicky Belgian yeasts though, not US-05.

However the best way would be to get a good vigorous yeast starter going for a couple days, then add that to the fermenter.  Just dumping a pack or two of dry yeast on top doesn't do anything -- it has to be a very lively vigorous yeast starter for it to work.  Some people would use champagne yeast but personally I would not do that -- just make a starter of a pack or two of US-05 for a couple days, and add that in.  I've not done this myself, but it might be the only thing that would work -- if that doesn't work, nothing else will, except maybe for that champagne yeast idea.  Or Brett!  Brett could also do the trick, but at the expense(?) of oddball Bretty flavors, and again, possible explosions if bottled too early.
Dave

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Offline Iliff Ave

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Re: 10 point FG difference
« Reply #16 on: November 25, 2015, 09:08:32 am »
Thanks. I actually added 3 day old slurry of K97, about 1/2 c. I thought my process was solid but I don't brew higher OG beers very often. I wish I would have thought of the champagne yeast.
« Last Edit: November 25, 2015, 09:10:59 am by goschman »
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Offline erockrph

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Re: 10 point FG difference
« Reply #17 on: November 25, 2015, 09:22:31 am »
I think 1.020 is close to where I'd expect a Baltic Porter of 1.078 OG to finish with US-05. It's the 1.010 FG that seems a bit out of line at first glance.

But I think I may have a possible explanation. You mashed your first batch for 3 hours in the mid 140's. That is the upper end of limit dextrinase range. Limit dextrinase is capable of converting dextrins that alpha-and beta- amylase cannot work on to fermentable sugars, leading to a much more fermentable wort. Your second mash was in the low 150's and would have denatured the limit dextrinase quite rapidly. Is that enough to account for 10 gravity points? I'm not 100% sure, but I do suspect that is where the majority of the difference is coming from.

Personally, I don't think the 1.020 batch is stuck and I wouldn't waste my time trying to get it to ferment down further if it tastes good.
Eric B.

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Offline Iliff Ave

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Re: 10 point FG difference
« Reply #18 on: November 25, 2015, 09:25:09 am »
I think 1.020 is close to where I'd expect a Baltic Porter of 1.078 OG to finish with US-05. It's the 1.010 FG that seems a bit out of line at first glance.

But I think I may have a possible explanation. You mashed your first batch for 3 hours in the mid 140's. That is the upper end of limit dextrinase range. Limit dextrinase is capable of converting dextrins that alpha-and beta- amylase cannot work on to fermentable sugars, leading to a much more fermentable wort. Your second mash was in the low 150's and would have denatured the limit dextrinase quite rapidly. Is that enough to account for 10 gravity points? I'm not 100% sure, but I do suspect that is where the majority of the difference is coming from.

Personally, I don't think the 1.020 batch is stuck and I wouldn't waste my time trying to get it to ferment down further if it tastes good.

Everything you just said has been exactly my thought the whole time. I thought mash 1 ducking below 148F for an extended amount of time while mash 2 staying above 150F might be the primary culprit. I was astonished by the 87% attenuation from batch 1. I never get that high with US05 and I use it frequently in all types of beers/OGs...
« Last Edit: November 25, 2015, 09:27:07 am by goschman »
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Offline denny

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Re: 10 point FG difference
« Reply #19 on: November 25, 2015, 09:33:17 am »
Okay, is it calibrated?  Does it read 1.000 in plain water at 60-70 F?  Something's just not adding up.  If it's none of these things, then I am as stumped as you are!!!
[/quote

It isn't gonna be off by 10 points if it isn't calibrated correctly.  At least I've never seen on off that far.
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Offline denny

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Re: 10 point FG difference
« Reply #20 on: November 25, 2015, 09:34:04 am »
I think 1.020 is close to where I'd expect a Baltic Porter of 1.078 OG to finish with US-05. It's the 1.010 FG that seems a bit out of line at first glance.

But I think I may have a possible explanation. You mashed your first batch for 3 hours in the mid 140's. That is the upper end of limit dextrinase range. Limit dextrinase is capable of converting dextrins that alpha-and beta- amylase cannot work on to fermentable sugars, leading to a much more fermentable wort. Your second mash was in the low 150's and would have denatured the limit dextrinase quite rapidly. Is that enough to account for 10 gravity points? I'm not 100% sure, but I do suspect that is where the majority of the difference is coming from.

Personally, I don't think the 1.020 batch is stuck and I wouldn't waste my time trying to get it to ferment down further if it tastes good.

I agree with all of this.
Life begins at 60.....1.060, that is!

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Offline dmtaylor

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Re: 10 point FG difference
« Reply #21 on: November 25, 2015, 09:34:37 am »
I'll confess... I haven't mashed a lot of beers less than 147 F.  Most typically I mash at 148-150 F.  Almost every beer, in fact.  It just surprises the hell out of me that just a few degrees could make so much difference.  I don't believe it.  I just don't.
Dave

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Offline denny

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Re: 10 point FG difference
« Reply #22 on: November 25, 2015, 09:37:31 am »
I'll confess... I haven't mashed a lot of beers less than 147 F.  Most typically I mash at 148-150 F.  Almost every beer, in fact.  It just surprises the hell out of me that just a few degrees could make so much difference.  I don't believe it.  I just don't.

To paraphrase Sherlock Holmes, when you've ruled out everything else, you;re left with the impossible.  There is really no other rational explanation that I can see.
Life begins at 60.....1.060, that is!

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Offline erockrph

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Re: 10 point FG difference
« Reply #23 on: November 25, 2015, 09:38:54 am »
Limit dextrinase activity in a long, low-temperature mash is a large reason why commercial adjunct lagers are able to finish so dry (as in sub-1.000 FG dry). I've gotten 83% attenuation on a 1.142 all-malt barleywine using a highly flocculant English yeast by targeting limit dextrinase in the mash.
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Offline dmtaylor

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Re: 10 point FG difference
« Reply #24 on: November 25, 2015, 09:40:51 am »
I'll confess... I haven't mashed a lot of beers less than 147 F.  Most typically I mash at 148-150 F.  Almost every beer, in fact.  It just surprises the hell out of me that just a few degrees could make so much difference.  I don't believe it.  I just don't.

To paraphrase Sherlock Holmes, when you've ruled out everything else, you;re left with the impossible.  There is really no other rational explanation that I can see.

Fascinating.  If true... fascinating.

EDIT: Oh my God.  Oh my God.  One beer I have brewed stuck out in my mind as finishing bizarrely dry.  I once made an English barleywine with a long mash that averaged 146 F, which has got to be the lowest and slowest mash I have ever done -- mash time was 160 minutes.  Probably started around 148 F and finished 144 F, something like that.  And..... I got 88% attenuation, final gravity 1.011, and fermentation was totally complete in just 2-3 days.  I was shocked and amazed.  Still am.

That limit-dextrinase....... man, that's some weird stuff.  I'm sure it helped that the mash time was long.  But even so.  That's some crazy stuff.  And the beer didn't taste super dry.  Just was very well attenuated.

Mind blown.
« Last Edit: November 25, 2015, 09:45:03 am by dmtaylor »
Dave

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Offline HoosierBrew

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Re: 10 point FG difference
« Reply #25 on: November 25, 2015, 09:45:18 am »
I think 1.020 is close to where I'd expect a Baltic Porter of 1.078 OG to finish with US-05. It's the 1.010 FG that seems a bit out of line at first glance.


That was my thought, too.  An extended mash in the mid 140s would make a much more fermentable wort. I've mashed several beers in the 146-147 range and noticed the difference. 
Jon H.

Offline jeffy

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Re: 10 point FG difference
« Reply #26 on: November 25, 2015, 11:50:19 am »
I think 1.020 is close to where I'd expect a Baltic Porter of 1.078 OG to finish with US-05. It's the 1.010 FG that seems a bit out of line at first glance.

But I think I may have a possible explanation. You mashed your first batch for 3 hours in the mid 140's. That is the upper end of limit dextrinase range. Limit dextrinase is capable of converting dextrins that alpha-and beta- amylase cannot work on to fermentable sugars, leading to a much more fermentable wort. Your second mash was in the low 150's and would have denatured the limit dextrinase quite rapidly. Is that enough to account for 10 gravity points? I'm not 100% sure, but I do suspect that is where the majority of the difference is coming from.

Personally, I don't think the 1.020 batch is stuck and I wouldn't waste my time trying to get it to ferment down further if it tastes good.

I agree with all of this.

Me, too.
Jeff Gladish, Tampa (989.3, 175.1 Apparent Rennarian)
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Offline Iliff Ave

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Re: 10 point FG difference
« Reply #27 on: November 25, 2015, 12:04:59 pm »
Thanks all. I have never done a 3 hour mash and I have never gone below 148F. The goal was to stay at 148F but I did not account for temp loss over 3 hours. For batch 2 maybe I should have shot for 150F knowing that it would likely duck below 148F for a little bit. I was hoping for something more along the lines of 1.015 but I get that's just a number. As long as the beer is good that is all that matters I suppose and this has been quite a learning process.
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