Beer Forum

I'm fairly new to lager beers, I've made 2 that turned out pretty good. I was trying to remember the fermentation/lager schedule that Gordon metioned on the show. It seems to me that it was 1 week primary, and 4-6 at almost freezing. When is a good time to do the diacetyl rest, right after primary or later?

usually right after primary
BUB

The thing about lagers is that fermentation is soooo much of the beer, that it can be critical.

As bub says, if you want to do a D rest, do it right toward the end of fermentation. Generally, with a Plato or two left to ferment.

However, that isn't the way I do it.

Me, I pitch cold (like GB) around 43F to 44F. Then I let the beer warm up to 48F to 50F though the natural heat of fermentation. Of course, you need to pitch the right amount of yeast for this to work. I let this sit for 4 weeks. No racking, no secondary, no D rest. After 4 weeks, I have a flawless lager, which I rack to a keg and carbonate. It is pretty much ready to drink at that point.

If it is a big lager, like a bock, it generally goes up to 6 weeks of fermentation.

jamilz wrote:I let this sit for 4 weeks. No racking, no secondary, no D rest. After 4 weeks, I have a flawless lager, which I rack to a keg and carbonate. It is pretty much ready to drink at that point.

What is the temp that you keep it at during these 4 weeks?

Diacetyl rest can be done in different ways:

- let the beer warm up a little after primary fermentation is done
- let the beer sit at fermentation temp for a little longer
- cool the beer down (~40F) and let it sit there for a while. (this is what Dan G. does)

The colder, the longer it will take the yeast to take up the residual diacetyl.

I like to raise the temp a little. Though I usually do not have noticable diacetyl in my beer towards the end of primary fermentation I want to give the yeast an incentive to go after the last fermentable sugar and get the FG towards the actual limit of fermentation.

Kai

Thanks guys, I'm going to brew here in the next week or so and see how things go.

I've never heard of anybody cooling down their beer and calling it a diacetyl rest. Pretty much everyone would understand the term to refer to a warming of the beer to highten yeast activity to convert the diacetyl to acetoin and then 3-hydroxy-2-pentanone.

Yes, it might also convert some diacetyl very slowly at colder temps, but it can get stuck at the acetoin phase and not go to completion, lending a musty smell to the beer. I would think if you chilled the beer to 40F, you would get pretty much no conversion. I don't think Dan said they did that. As I recall, his procedure was the same as mine, with the addition of some cold lagering time (but not for diacetyl reduction).

The purpose of the cold, slow ferment is to prevent diacetyl in the first place. This is one of the problems with pitching lager yeast into a warm wort, you'll generate far more diacetyl and then you need to figure out how to get rid of it at the end. Probably the reason so many homebrewers are focused on diacetyl rests.

If you start out cold and let the beer slowly warm up toward the last 50% of fermentables, you won't need a diacetyl rest.

If you're fermenting warm, you'll need to warm up the beer even more near the end of fermentation to convert the diacetyl. If you cool it down, you will never get rid of the diacetyl.

jamilz wrote:I've never heard of anybody cooling down their beer and calling it a diacetyl rest.

I'm pretty sure I heard Dan say that. I will have to go back to the archives to check on this. I remember it because it sounded to couterintuitive and I was wondering why none of you guys said anything regarding this cold diacetyl rest.

I do however concur with the rest you say about diacetyl and the prevention/removal of it.

Kai

jamilz wrote:Me, I pitch cold (like GB) around 43F to 44F. Then I let the beer warm up to 48F to 50F though the natural heat of fermentation. Of course, you need to pitch the right amount of yeast for this to work. I let this sit for 4 weeks. No racking, no secondary, no D rest. After 4 weeks, I have a flawless lager, which I rack to a keg and carbonate. It is pretty much ready to drink at that point.

If it is a big lager, like a bock, it generally goes up to 6 weeks of fermentation.

A couple questions about this:
1 - what is your AMBIENT temp when you are letting rise naturally? Is it kept at 48f - 50f, lower??

2 - When you say you let it sit for 4 weeks, is this at 48f - 50f, or do you lower the temp?

3 - finally, if it's a more complex lager, like a Martzen vs a CAP, would you let it "condition" longer, like you said for the Bock?

Thanks!

Rob