Does D-rest remove ALL diacetyl flavor?

[DrinkNoH2O]

Hi All,
I just brewed my first lager and have completed a 3 day long diacetyl rest. I just took a taste and I can still taste some definite diacetyl, though it's much less than 3 days ago when the rest began.

Here's my recipe, a scaled down version of Yooper's Oktoberfest:

Style: Oktoberfest/Marzen
Batch Size: 2.50 gal
Boil Size: 3.30 gal
Estimated OG: 1.054 SG
Estimated Color: 12.3 SRM
Estimated IBU: 25.3 IBU
Brewhouse Efficiency: 70.00 %
Boil Time: 60 Minutes

Ingredients:
------------
Amount Item Type % or IBU
4.40 lb Vienna Malt (3.5 SRM) Grain 81.48 %
0.50 lb Munich Malt (9.0 SRM) Grain 9.26 %
0.25 lb Caramel/Crystal Malt - 80L (80.0 SRM) Grain 4.63 %
0.25 lb Caramunich Malt (56.0 SRM) Grain 4.63 %
0.45 oz Tettnang [4.80 %] (50 min) Hops 14.3 IBU
0.45 oz Hallertauer Hersbrucker [4.60 %] (30 min)Hops 11.0 IBU
1 Pkgs German Lager (White Labs #WLP830) Yeast-Lager


Mash Schedule: Lager Mash
Total Grain Weight: 5.40 lb
----------------------------
Lager Mash
Step Time Name Description Step Temp
30 min Beta rest Add 5.94 qt of water at 155.3 F 140.0 F
30 min Alpha Rest Add 2.54 qt of water at 210.0 F 158.0 F


The brew day went well - hit the OG right on the nose, and I used WLP830 as that was the most suitable lager yeast for an Oktoberfest that my LHBS carried.

I was in real doubt about the best approach to begin the fermentation, so I followed the White Labs directions and pitched a stirplated/decanted 2 qt. starter at about 68*F and waited until I saw activity (about 4 hours) to start bringing it down to 52*F for fermentation. (I now understand that I should have pitched at fermenting temps to reduce diacetyl production - live and learn).

The fermentation went great, holding at a steady 52*F and it dropped from 1.054 down to 1.019 in 5 days. This is when I took the carboy out of the fridge and let it come up to room temp - about 70*F (I know, D-rest should be about 10*F above fermentation temp, but I have no means to hold a 62*F temp).

When I first started the rest, I tasted quite a bit of diacetyl (just like butter toffee, etc.). After 3 days the gravity finished up at 1.013 - right where I wanted it to - however the is still some detectable diacetyl flavor (however the beer tastes flawless besides that fact).

So my question is this: Should I go ahead and rack to secondary and begin the lagering phase knowing that I've done a 3 day D-rest and reached terminal gravity? Does the D-rest remove ALL diacetyl flavor, or does it just remove most of it and the lagering phase will remove the rest?

 

[mlg5039]

Leave it for another week. Then, rack and lager it.

 

[The_Professor]

Personally I am not sure you ever get rid of all the diacetyl once it is introduced to your brew. Conditioning helps.

Like you said-pitch at fermentation temps, and consider using twice as much yeast for a lager as you would for an ale.

I have found it is best to never have any diacetyl to need a "rest" for.

 

[Yooper]

If you actually can taste the diacetyl, the diacetyl rest needs to be continued as it'll get worse with time, not better.

 

[DrinkNoH2O]

If you actually can taste the diacetyl, the diacetyl rest needs to be continued as it'll get worse with time, not better.

Was hoping you'd chime in, thanks Yooper!

I'll prob give it a few more days then. I saw some other threads warning about getting off flavors in a lager by doing too long of a D-rest at a high temp but I have a hard time believing too many more off flavors could be introduced at this stage in the game. Definitely less than the diacetyl I could potentially get rid of I think.

 

[JKoravos]

Leave it until it's gone. I've had beers that I was ready to dump after two weeks clean up completely.

 

[DrinkNoH2O]

So glad I asked about this and decided to continue the D-rest! Tasted the beer this morning and it's noticeably improved even further. Hardly any diacetyl flavor detectable now. I'll prob let it go one or two days longer then start ramping down the temp to begin lagering phase.

I am shocked how much diacetyl was produced by WLP830 (especially when I pitched a full tube stirplated on a 2 qt starter for a 2.5g batch) when pitching at room temp.

Next time I will definitely pitch at fermentation temp.

 

[Homercidal]

My first lager I did the pitch at 50 and let it go then drop to 33. Seemed to work ok, but my bad water and low pitch rate didn't help the flavor.

My second, a CAP I did the same, but used better water and more yeast and I think it tastes pretty good. Then again, I have a high tolerance for Diacetyl I think, so I have to rely on others for tasting.

I think that 830 yeast is kind of touchy. I'd probably pitch at 50 and just let it take it's time to get going. It's been known to do that.

 

[DrinkNoH2O]

Now that the diacetyl issue appears to be resolved, I started thinking about CO2 levels when bottling...

Typically I carb to style/temperature via Beersmith's calculations for priming sugar. In this case I'm curious what temperature to input to estimate the amount of dissolved CO2.

If I would have not done the extended D-rest and kept the beer cold I could assume that the bulk of the CO2 remained dissolved and use the fermentation temp (52*F) as the temp. for Beersmith's bottling/priming sugar volume calculator.

Since I've done this extended rest maybe I should use the rest temp (70*F) since a lot of CO2 likely escaped?

If so, Beersmith is telling me to use about 2.37 oz. corn sugar to get 2.6 volumes in this 2.5 gallon batch. Sound good?

 

[DrinkNoH2O]

Just wanted to follow up on this. I lagered the beer for about 40 days and then bottled (using 70* as my temp to calculate sugar as I let it come to room temp first).

It's been in bottles about 3 weeks now and tastes fantastic. Not a hint of detectable diacetyl at all. So glad I just continued the rest.

Can't wait to brew my next lager! Will likely be a Munich Helles.

Thanks all!