D-rest timing...

[ShortSnoutBrewing]

It's not the same question, I promise. At least I hope not, I couldn't find the answer I was looking for anyway...

So for a diacetyl rest we all know to raise the temp to 60º-65º for a few days. When done you start lowering the temp 2º-4º a day until you get to your lager temp. So I have a guideline to get to lagering temps, but nothing for getting to d-rest temps. My set up is a chest freezer with heater and 2 way temp regulator. I use one of them orange carboy caps with a thermowell in one opening and my blowoff tube on the other, so the temp sensor is in the middle of the beer.

Do I slowly want to get to 60º? Shut off the heater and freezer and open it up to allow it to warm naturally? Do I keep it closed and let the heater take over and as quickly as it can heat up the beer? What's the thought on that?

 

[Yooper]

good question! I don't have Noonan's book handy, so I'm going to have to say to go ahead and just do it. Not to ramp up the temp that quickly, but allow to get to 10 degrees above fermentation temperature when the primary is about 75% done. So, if the SG is 1.020 today, for example, I'd go ahead and let it raise up to 65 by simply turning off the temperature control and opening it up to room temperature assuming your room temperature was in the 65-70 degree range.

The point of the diacetyl rest is for the yeast, which are still active as primary is dying down, to consume the diacetyl. They'll do that after the preferred sugars are gone, whether it's at a cooler temperature or a warmer temperature, but they'll do it more quickly and completely at a warmer temperature. Given enough time and enough yeast, even keeping it at 50 degrees will eventually clean up the diacetyl.

So, that's my "beat around the bush" way of saying that it probably doesn't matter, as long as you don't shock the yeast by raising or dropping the temperature too quickly.

 

[r2eng]

I have spent the last 2 year's winter season brewing lagers, and Yoop's dead-on.

After the D-rest, be sure and drop to lager temp and let it sit there for 2 months. I know, I know: It's a b!tch to wait that long, but you will be rewarded.

Thanks to advice like Yooper's and others here, I now have a Vienna lager worthy of competitions. My Vienna will be entered this March!

 

[ShortSnoutBrewing]

Thanks Yoop...I was actually hoping/expecting you'd be the first to answer!

I'm actually more than 75% done at this point if I did my math right. Started at 1.088 (dopplebock), now at 1.029 with a hope of 1.019 as the FG. So within 10 points of my FG. I'm using Munich Lager yeast, which from what I can tell, a heavy diacetyl producer.

 

[ShortSnoutBrewing]

Thanks r2eng....Lager period will be a bit longer than 2 months though. As I stated above, I did up a Dopplebock...Probably won't get my first taste of this till July/Aug!

 

[r2eng]

ooooh! I have never made a Dopplebock!

MMMMmmmmm sounds great! You should be able to taste any diacetyl from a sample before lagering. I have read Noonan's book and a whole lot of other sources, and it seems to me that flaws will show themselves after the diacetyl rest: cold crash and taste a hydrometer sample before lagering. My experience with Pilsner and lagers is that the flavor of the finished beer is very similar to the pre-lagering sample. Less smooth, but flaws are somewhat apparent.

 

[bbone66]

KB I just brewed a Vienna Lager and a Munich Helles with the same set up as yourself. Fermented @ 48deg. for three weeks then "went for it" just cranked the Fermwrap up to 58deg. for 5 more days. Cold crashed (over 3 days) and keged. Sample tasted great with no signs of diacetyl. I don't know if it was totally by the book but it seemed to work.

 

[menschmaschine]

It's not good to shock yeast in any way, but you don't need to "slowly" warm up to D-rest temps. You can warm it up as fast as you want as long as the yeast aren't shocked.

Some lager brewers don't even slowly lower temps to lagering temps. The only reason I can find to do so is that Briggs (Brewing Science and Practice) states that shocking lager yeast with cold temps can cause them to release proteolytic enzymes, reducing foam stability. I don't think this is an issue with raising temps. Brewers who don't slowly lower temps to lagering say they don't notice a problem with this, but I prefer to play it safe and slowly lower the temps. As for raising to D-rest temps, I just open the freezer for a few hours to raise the temp. If I could warm it up quicker, I would... but not too quickly... like, I wouldn't put the carboy in a giant microwave or anything.

 

[ShortSnoutBrewing]

OK, so what I did last night was just shut everything down and left the lid on the chest freezer open. Checked when I got home tonight and it got it self up to 58º. Didn't see the harm in giving it a hand at this point so I closed up the freezer and plugged the temp controller back in to help it get up to 61º for a few days.

 

[gxm]

If you really want to be sure about diacetyl, I've read folks writing about doing a test where you take two samples. Chill one to 40F, and heat the other in the microwave to 140F, and if you can't taste diacetyl, you're golden. Granted, I've not done this myself, and I haven't had any diacetyl issues with 95% of my lagers.

 

[robertjohnson]

Just brewed my first lager and am wondering the same thing. I have three water baths that maintain fairly constant temps of 50*, 60*, and 66*. In my experience, the temperature of the fermenting beer has been within about one degree of the bath and this is holding true for the lager. The temperature adjusts within a couple of hours, so I'm concerned that if I just drop the lager into the 60* bath it'll shock the yeast and create off-flavors. From what's been said this isn't a huge concern, but I just want to make sure since this warming process is faster than what Yooper suggested (water conducts heat better than air?). Eventually I hope to have the lager sitting in the warmest bath. How's that sound for a plan?

Also, sorry to drop the n00b question but I nailed everything so far and want it to turn out: I do this at 75% of anticipated FG and hold it for 2-3 days, right?

Thanks for any help!!