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Taste diacetyl in my first Pilsner :(

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skarz

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I have brewed a number of ales which have all turned out delicious, and recently I attempted my first Pilsner (92% Pilsner malt, 8% flaked wheat) which did not turn out how I expected. There is a prominent off-flavor, it tastes mostly like butter scotch but I can't quite put my finger on it. After the boil I chilled to room temperature and pitched Wyeast Bohemian Lager at room temperature then brought my fermentation chamber down to 55°F.

Fermentation Timeline
9/10/20 Pitch yeast at room temp, slowly bring down to fermentation temp
9/10/20 1.056 55°F
9/13/20 1.027 60°F (diacetyl rest)
9/14/20 1.013 60°F
9/19/20 1.011 35°F
9/29/20 1.011 35°F (transfer to keg, carbonate, and add fining agent)

Looking at the numbers above, where did I more than likely go wrong?
 

bobeer

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You're supposed to do a diacetyl rest after fermentation has completed since it's produced during fermentation. I usually do mine closer to 70 degrees for 2 days or so.

Edit: sorry, didn't see the dates.. Looks like you did the diacetyl reset after fermentation. Perhaps it wasn't warm enough?
 
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skarz

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You're supposed to do a diacetyl rest after fermentation has completed since it's produced during fermentation. I usually do mine closer to 70 degrees for 2 days or so.
Everything I've read indicated that diacetyl rest should be done prior to hitting FG. From White Labs:

The process is simply to raise the fermentation temperature from lager temperatures (50-55F) to 65-68F for a two day period near the close of the fermentation. Usually the diacetyl rest is begun when the beer is 2 to 5 specific gravity points away from the target terminal gravity.
What am I misunderstanding?
 

bobeer

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Maybe the 60 degrees you say you did the rest at wasn't warm enough? 60 isn't 65-68 so maybe it just wasn't warm enough to fend off the diacetyl. I know when I used to naturally carbonate in bottles... the rule is 3 weeks at 70 degrees... I had mine at 68 degrees and they didn't carb well or taste clean until I got it 70 degrees.

I've used several different kids of yeast and I always bring up the temps about about a week or so in primary. I've never really bothered to see if fermentation is 100% complete or not but I assume it's just about done. I just check to make sure the krausen has fallen so it's not in primary fermentation still when I bump up the temps and I've never had an issue.
 

Maxkling

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Do an easy Diacetyl Test at the end of your rest. I don’t think you were warm enough. The tests can be completed with your hydro samples and only takes 20 minutes or so.

Easy work to prevent a bad batch.
 

apache_brew

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Pitching at "room temperature" didn't help you. Ideally you'd pitch in the 50F range after quickly getting there from boil. I've read that pitching low and ramping up to the fermentation temperature (opposite of what you did) eliminates generation of diacetyl and as a result eliminates the need for D-rest. The amount of time and 5F temp difference seems sufficient.

On the other hand, are you sure it's not DMS? Not having lager experience before, did you boil hard for 90 minutes? Are you sure it's not a canned corn flavor? I just brewed my first 100% pilsner malt lager and brought a sample for my local brew-pub to sample. They pissed in my cornflakes (pun intended?) by calling it out as a DMS bomb. I traced it back to my weak boil after experiencing multiple boil overs on brew day and trying to compensate with a lower flame.
 

dmtaylor

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If you warm it up to room temperature, the diacetyl will most likely age out by itself after about 3-4 weeks. That's been my experience. There is still yeast in there that can eat it at warm temps, just takes a while.
 
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skarz

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Pitching at "room temperature" didn't help you. Ideally you'd pitch in the 50F range after quickly getting there from boil. I've read that pitching low and ramping up to the fermentation temperature (opposite of what you did) eliminates generation of diacetyl and as a result eliminates the need for D-rest. The amount of time and 5F temp difference seems sufficient.

On the other hand, are you sure it's not DMS? Not having lager experience before, did you boil hard for 90 minutes? Are you sure it's not a canned corn flavor? I just brewed my first 100% pilsner malt lager and brought a sample for my local brew-pub to sample. They pissed in my cornflakes (pun intended?) by calling it out as a DMS bomb. I traced it back to my weak boil after experiencing multiple boil overs on brew day and trying to compensate with a lower flame.
I don't think it's DMS. I brought a sample to my LHBS and both guys there tasted it and said they tasted no apparent off-flavors but maybe a slight hint of diacetyl. So either a) I am hyper sensitive to diacetyl (no previous experience to support that) or b) I am mistaking the flavor. I'm new to using pilsner malt so I don't really know what 'normal' tastes like. This is a 'west coast' pilsner recipe so maybe I'm just picking up combinations of the pilsner malt and hops. I think what I was initially determining to be butter scotch might acually just be a malt / bread / hop flavor combination.
 

Bobby_M

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A few things.

If it was one pack of yeast, even if it was packed that same week was an underpitch of biblical proportions (assuming a 5 gallon batch). Ok, maybe I'm being hyperbolic but even if the pack was fresh, you would have done well with 3-4 packs or a 2 liter stirred starter. If it was a few months old, it was even worse.

Pitch lager yeast at the rock bottom of its operational range (mid to upper 40's for that strain) and then set your controller for a couple degrees up from there.

Your timeline is way too short. You cold crashed too fast which ended the diacetyl cleanup activity. If you pitch a healthy cell count at fermentation temps, you would likely start the diacetyl rest climb at about day 7 and you should hold it there for at least another week.
 

Sammy86

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Fermentation Timeline
9/10/20 Pitch yeast at room temp, slowly bring down to fermentation temp
9/10/20 1.056 55°F
9/13/20 1.027 60°F (diacetyl rest)
9/14/20 1.013 60°F
9/19/20 1.011 35°F
9/29/20 1.011 35°F (transfer to keg, carbonate, and add fining agent)
This is your problem.

1. As bobby said above you have to pitch low because once the yeast start eating the sugar its going to warm up.

2. You need to keep your fermentation temp consistent for at minimum 3-4.m days...max 14. Once fermentation is close to being finished/is done raise the temp to 65-68 degrees for D-Rest...if you're feeling frisky go EHDR (extra hot diactyl rest) and get it up to 70-72.

3. You need to lager it...2 weeks minimum...ideally 6-8 weeks will really help develop flavors and balance.

Live and learn and brew on!

:mug:
 

Beermeister32

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I agree with the previous responses. 2L big starter. Pitch at 48-50F. Ferment at 50F. Near the end of fermentation, begin ramping up to 66F D-rest. You can hold the D-rest from a couple days to a couple weeks. Keg it at 66F then begin lagering it at 34F. Also, always do 90 minute boils with Pilsner malt.

To try to repair this batch, I would bring your keg inside your house, find a cooler spot on the floor somewhere around 66F and let it sit there for a few weeks. Sometimes you can also add an amount of another strain of yeast at the same time (for example if you used a lager yeast for your fermentation, add a half pack of neutral ale yeast like US05 directly to the keg and repurge). It will help finish out the beer and uptake remaining O2 from the beer if you can deal with the indignity of finishing a lager with a little ale yeast. After 2-3 weeks sitting there at 66F or room temp, bring it down to 34F for your lagering period, ideally 60-90 days. Lagers improve incredibly from aging, if you can keep from drinking it!
 
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