Diacetyl rests in lagers

I've read a bit on d-rests and the general school of thought is to warm the beer from 50-ish to almost 70 when fermentation is about 2/3 or 3/4 of the way complete, then transfer and gradually lower the temps about 5 degrees a day until you get around 32-ish. Then lager here for a month or two.

(You'll notice there is a lot of general terms, but that's how brewing is.)

I followed this a couple times and was not very satisfied with the outcome. It tasted as if there was a little too much residual sweetness despite a very clean grain bill. The taste may have been the yeast, but I used a liter starter and pitched at 50F.

So I'm not sure what the culprit is, but I want to focus on the d-rest. Would a good practice be to simply ferment at 50F for a full month, transfer, and then slowly lower temps to lager around 32F for another couple months?

My ales usually ferment on the cool side for 4 weeks in primary and then go straight to keg, and turn out great, so I'm not afraid of long primaries.

Thanks.

If you're pitching at 50F, my understanding is that you're fine to skip the D-rest.

JoePolvino said:

So I'm not sure what the culprit is, but I want to focus on the d-rest. Would a good practice be to simply ferment at 50F for a full month, transfer, and then slowly lower temps to lager around 32F for another couple months?

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That's what I and other have beer recommending (see here) as the reduction of diacetyl will happen at any temp and is only a matter of time and yeast health.

To battle the sweetness, do a forced ferment test (same article) to see if it comes from mashing or fermentation.

Kai

I recommend actually trying the beer to see if you even need a diacetyl rest. If so, I often do so after racking (or kegging, as the case may be).


TL

TexLaw said:

I recommend actually trying the beer to see if you even need a diacetyl rest. If so, I often do so after racking (or kegging, as the case may be).


TL

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That's exactly what I did just before the d-rest and then about a month into the lagering.

For the former, it simply tasted young and still had residual sweetness, so I went ahead with the rest.

After a month lagering, it was hard to get a good taste reading due to it being flat. I let it go another month around 38F.

So I'm a little which is why I'm considering a long primary to give the yeast time to clean up at a temp where they are still active and plentiful. Thoughts?

JoePolvino said:

So I'm a little which is why I'm considering a long primary to give the yeast time to clean up at a temp where they are still active and plentiful. Thoughts?

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Yes, a longer primary will help with better attenuation. One problem with lagers is that you start lagering to early and the yeast will slow down to much to be able to reach the desired attenuation. I had this problem often during my first batches since I was eager to get the beer to lagering.

Kai

I've been having the same problem....It taste fine after primary.. once it's carbed and out of lagering it tastes to sweet.I'm going to re-pitch my latest batch[7.75 gal] and hope it cleans up again after a month or so... I usually let primary sit for at least three weeks..then another month or two. I think maybe after the rest i will let it set for another two weeks at 50 or higher.. then go to lagering temps.

JoePolvino said:

So I'm a little which is why I'm considering a long primary to give the yeast time to clean up at a temp where they are still active and plentiful. Thoughts?

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That's really the way to do it. By the way, you can get a buttery sort of flavor, sometimes, in a green beer. The way you really know you have diacetyl is by that slick (or, at least, weird) mouthfeel.


TL

I like the idea of the longer primary. I have done 4 weeks on the last couple of lagers and no d-rest. It just seems to give the yeast the time it needs to clean up everything.

Everyone is way too eager to get beer out of the primary. Let it go and let the yeast work their magic. This goes for ales and lagers.

I use the following:

Ales 14 days in the primary and then keg.
Large ales can take longer!

Lagers up to 1 month depending on OG. in the primary. Keg and lager for 1 to 2 months.

Use 2 liter yeast starters (decanted). This means that you made a 2 liter starter and cooled it at 40F and decanted off the liquid before pitching into 40F wort. Slowly raise to 53F.