Diacetyl rest: when to do it

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Kaiser

Kaiser

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Hi There

I was told that the diacetyl rest for lagers is especially important if yeast is pitched warm (at 70F and not at lager fermentation temperatures of 50). So far I have been pitching warm (in order to get some better yeast growth before the start of the fermentation). But I have been neglecting the diacetyl rest.

I plan to make one for the Berchtesgadener Hell clone that I have in the primary. It has been there for 10 days and is bubbling at a rate of 8 bpm (bubbles per minute). Which is still pretty active. But I need the yeast slurry for the Optimator clone that I plan to brew on Sunday. That's why I plan to rack it to the secondary on Saturday.

Now my question is, should I do the diacetyl rest before I rack to the secondary or should I do it in the secondary once the activity has slowed down much more?

I will be getting a lots of books on this (How To Brew and New Brewing Lager) for my B-Day, which is coming up, but I'm kinda in a hurry with the Optimator clone since It needs to be drinkable for easter.

Kai
 
kai, according to Gregory Noonan's New Brewing Lager Beer he says:

"if a diacetyl rest is being employed, force the temperature of the post-kraeusen ferment to rise to 55-60 degrees. after two days, lower the ambient temperature again, bringing the beer down to 38 to 40 degrees at 3-5 degrees per day.

when the extract drop slows to 0.5 plato (sg 1002) over 24 hours, the head will have completely fallen. rack the beer into a secondary fermenter/lagering vessel."

my understanding is to do the rest in the primary, because the yeast will consume the diacetyl it has produced. it's the way i've always done it.....
 
Now, If I rack to the secondary before the fermantation is complete, making sure ther thee will be enough yeast to finish the job, I will have to do the diacetyl rest there.

One constraint I have, is that I need to harvest the yeast for Sunday. So if I rack to secondary, harvest, wash and refresh the yeast and pitch some of this yeast into the secondary, I should be fine. The only thing I would have done is removing some of the yeast and the trub. The yeast will even be refreshed with some oxygen. (I'm not planing to oxygenate the beer, just the starter that all that yeast will go into)

Kai
 
hhmm? i dunno kai. sounds like a lot of extra work to me, but it would probably work.

i don't know if you get BYO, but a regular contributor Horst Dornbusch always says to rack after the diacetyl rest. i think it defeats the purpose of the diacetyl rest w/ out the yeast to consume it. just skip the whole step. might not notice a difference....
 
I know it's extra work. But I need lots of yeast for this weekends brew. So I need to harvest it. I guess if I give some of the yeast back after racking then I cannot really call it racking to a secondary. I can only call it harvesing yeast and removing the trub.

I'll take a reading tonight to see how far along the brew actually is.

Kai
 
When the fermentation is nearing completion and the yeast is running out of fermentables, the yeast will consume the butterscotch like fermentation by-products if the temperature is raised to 55 - 60 deg. F. Gently changing the temperature up and down before and after the rest is completed reduces the chances of shocking the yeast and producing a stuck fermentation.
 
Kaiser said:
Hi There

I was told that the diacetyl rest for lagers is especially important if yeast is pitched warm (at 70F and not at lager fermentation temperatures of 50). So far I have been pitching warm (in order to get some better yeast growth before the start of the fermentation). But I have been neglecting the diacetyl rest.

I plan to make one for the Berchtesgadener Hell clone that I have in the primary. It has been there for 10 days and is bubbling at a rate of 8 bpm (bubbles per minute). Which is still pretty active. But I need the yeast slurry for the Optimator clone that I plan to brew on Sunday. That's why I plan to rack it to the secondary on Saturday.

Now my question is, should I do the diacetyl rest before I rack to the secondary or should I do it in the secondary once the activity has slowed down much more?

I will be getting a lots of books on this (How To Brew and New Brewing Lager) for my B-Day, which is coming up, but I'm kinda in a hurry with the Optimator clone since It needs to be drinkable for easter.

Kai
Click to expand...
Is it too much to ask you to get off your lazy axe and do a google search. All kinds of good information out there. LINK















:p
Sorry, but I've been reading a lot of your blog recently and just couldn't resist.
 

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