Author Topic: Diacetyl rest left too late?  (Read 1530 times)

Offline egg

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Diacetyl rest left too late?
« on: January 01, 2017, 04:04:43 PM »
I'm within a couple of points of my expected FG on a Pilsener, unexpectedly soon.  There's a big sulphur smell and some diacetyl to my taste, though it otherwise taste very promising.  OG was 1.047; SG currently 1.011, 5 days after pitching two rehydrated sachets of 34/70 into 21L. It's been at 54f throughout.

This is my first lager, so I'm a little unsure what to expect from here.  I've reset the brew fridge to 65f, but will this be too late to have a good effect on cleaning up the brew?

This was based on a friend's recipe, but I undershot my gravity, while pitching twice as much yeast.  I thought I'd adjusted the timescales enough in my mind before taking an SG, but it's gone quicker than my shortest expectation!

Offline dmtaylor

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Re: Diacetyl rest left too late?
« Reply #1 on: January 01, 2017, 04:14:59 PM »
It will still clean up fine in my experience.  You did the right thing warming it up.  65 F is a good conditioning temperature to clean up sulfur and diacetyl.  Keep it there for as long as it takes (a week? not sure), then you can bottle or keg right away, or lager in the fermenter, at your option.
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Offline natebrews

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Re: Diacetyl rest left too late?
« Reply #2 on: January 01, 2017, 04:24:24 PM »
Yeah, like he said, it will be fine.  Have patience and it'll work out.
Risk of failure should be no deterrent to trying.

Offline egg

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Re: Diacetyl rest left too late?
« Reply #3 on: January 01, 2017, 05:59:10 PM »
This is reassuring to hear.  Thanks both.

It may sound funny, but I was surprised how lager-like the brew tasted already, regardless of the byproducts.

Offline santoch

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Re: Diacetyl rest left too late?
« Reply #4 on: January 01, 2017, 06:41:01 PM »
^^ What they said.

"As long as it takes" is key.  Keep tasting until the diacetyl is gone, and don't be afraid of adding esters or anything due to high temps now that it's nearly finished.  Those compounds were created long ago, and warmth now will only make it better.
 
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Offline egg

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Re: Diacetyl rest left too late?
« Reply #5 on: January 01, 2017, 06:54:10 PM »
OK, as long as it takes.  There's no rush, seeing that the vessel in which I'm planning to lager the beer may be a week or so away from delivery. 

I'm planning to lower in steps of 4 or 5f  per day to get from 65 down to around 34, once I'm happy with the clean-up.  I guess I will do that in the primary, before transferring.

Offline egg

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Re: Diacetyl rest left too late?
« Reply #6 on: January 07, 2017, 01:42:34 PM »
An update on that, with a new concern:

This is my pilsner, which went from 1.047 down to 1.011 in 5 days at 54f, at which point I cranked it up to 65f.  It's now been having that diacetyl rest for 6 days, which is longer than the first part of the fermentation.  I can still taste diacetyl, thought the sulphur quickly went away.  Over the last two days, I have detected a new aroma and, to some extent, taste, which seems to be replacing the fresh taste and aroma it at least had a few days ago.  It's nothing acetic or sour, more of a meaty (?) smell.  Knowing some common descriptors, that would sound like autolysis, though I always see confident advice that we're unlikely to suffer from that in small batches over anything but a very extended period.

There is still a lot of yeast in suspension.  I tried a sample from the top, as well as the bottom tap: both showed some diacetyl, to the best of my sensory awareness (popcorn, for me).  The bottom sample had more of a tang to it, which I imagine was the higher density of suspended yeast.

SG is now 1.0065, around 86% attenuation, so I guess I'm looking at a pretty thin Pilsner :(

With the taste getting worse rather than better now, I'm wondering whether to start to lower it for lagering and hope when it clears down it is OK?

Offline natebrews

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Re: Diacetyl rest left too late?
« Reply #7 on: January 07, 2017, 02:03:24 PM »
Are you sure you are getting diacetyl and not just fooling yourself into it? I've done that plenty of time, being paranoid about it and definitely being sure that it is there, when in retrospect I am pretty sure it wasn't.

Are you doing a heated diacetyl test (heat a sample for 15min and then cool and compare to see if more diacetyl showed up) or just strait pulls from the fermentor? 

Sometimes the yeast that is in suspension can seem like off flavors, but once they drop out it is fine.   I would be pretty surprised if you really had autolysis at 2 week, though maybe others have differing opinions on that one.
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Offline HoosierBrew

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Re: Diacetyl rest left too late?
« Reply #8 on: January 07, 2017, 02:15:32 PM »
Are you sure you are getting diacetyl and not just fooling yourself into it? I've done that plenty of time, being paranoid about it and definitely being sure that it is there, when in retrospect I am pretty sure it wasn't.

Are you doing a heated diacetyl test (heat a sample for 15min and then cool and compare to see if more diacetyl showed up) or just strait pulls from the fermentor? 

Sometimes the yeast that is in suspension can seem like off flavors, but once they drop out it is fine.   I would be pretty surprised if you really had autolysis at 2 week, though maybe others have differing opinions on that one.



Totally agree. If I'm questioning diacetyl, I like to put a small sample in the microwave it to ~ 100F. If there's any present, it's pronounced at the warm temp (ie.,  movie theater popcorn butter).
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Offline dmtaylor

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Re: Diacetyl rest left too late?
« Reply #9 on: January 07, 2017, 03:09:01 PM »
It's going to turn out just fine.  The meaty smell and tangy flavor is indeed from yeast, which will settle out in time.  The diacetyl also will fade within another week or so until it is totally gone.  I would NOT chill down the beer at this point, just leave it warm.  It's just fine.
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Offline egg

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Re: Diacetyl rest left too late?
« Reply #10 on: January 07, 2017, 03:19:04 PM »
OK, thanks for your advice, and I have to admit, I am now doubting whether what I'm getting as diacetyl is actually so.  I did a heated diacetyl test (which I've never done before) and could not detect any difference in the smell of the samples.  Just to confirm that, I split it up and did a triangle test with my wife and son, and neither of them picked any difference either, not that they had a clue what they were seeking.

The first time I pretty much knew I had diacetyl in a brew was in a pale with WY1469 (Taylors), which is known for it: there was a MASSIVE popcorn smell and taste during fermentation, though it did subside after a rest.  Maybe I'm picking up traces of the cara or something, and confusing that with popcorn.

dmtaylor - that's reassuring, cheers.

Offline bboy9000

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Re: Diacetyl rest left too late?
« Reply #11 on: January 07, 2017, 03:35:16 PM »
I love 1469 and never get diacetyl from it.  Maybe it is a malt thing.  How much cara/crystal did you use?
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Offline egg

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Re: Diacetyl rest left too late?
« Reply #12 on: January 07, 2017, 03:46:11 PM »
I love 1469 and never get diacetyl from it.  Maybe it is a malt thing.  How much cara/crystal did you use?

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3.300 kg Pilsner (73.99%)
0.500 kg Munich I (11.21%)
0.200 kg Carapils (Dextrine) (4.48%)
0.200 kg Torrified Wheat (4.48%)
0.160 kg Acidulated Malt (3.59%)
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Offline natebrews

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Re: Diacetyl rest left too late?
« Reply #13 on: January 07, 2017, 04:00:44 PM »
I'm still convinced the diacetyl is just in your head.  You could probably tell people you put twizzlers in there and they would pick it up after enough 'careful tasting'.
Risk of failure should be no deterrent to trying.

Offline dmtaylor

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Re: Diacetyl rest left too late?
« Reply #14 on: January 07, 2017, 04:01:36 PM »
Let's not be so sure.... we're not tasting the beer.  We can only guess.
Dave

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