Mixed Opinions on Diacetyl Rest For Lager

[Jmash]

I've heard varying opinions.
1) Start rest when at 75% of FG
2) Start rest after 21 days in primary
3) Start rest when at FG.

Thoughts?

 

[stratslinger]

I've always gone with option 1.

Option 2 seems silly to me - depending on your yeast and your wort, day 21 could be literally ANY stage of fermentation. Let the hydro be your guide, not the calendar, whether you choose to go with 75% of FG or FG itself.

At 75% of FG, you know the yeast are still active, and any part of the fermentation that should produce off-flavors is done with, so that should be a good time to do it and encourage the yeast to clean up the Diacetyl.

At FG itself, if you time it right, the yeast shouldn't be all dormant yet, so that _should_ work, but it may take a little longer to complete the rest than if you do it while you know the yeast are still active.

 

[dmtaylor]

Do a rest if the beer tastes like it needs it. Otherwise skip it. If it needs it, start when gravity is half of what you started with, e.g., 1.060 goes to 1.030. It is okay if you don't get the timing perfect but be as close as you can. Probably gets there in the first 4-5 days usually if you did a good healthy pitch.

 

[BlueHouseBrewhaus]

Option 1. Definitely not 2 or 3. If you have a really sensitive palet, you can taste it and skip the D-rest if you don't detect any diacetyl. But a standard D-rest at 75% attenuation is a foolproof and easy habit to get into.

 

[csurowiec]

Here is my non-scientific "It works for me" approach and FWIW the only lager yeast I have used is Saflager 34/70.
Start to warm it up for a D rest when the krausen falls which at 53 degrees fermentation chamber temp is about 6-7 days in. I do not take a gravity measurement at that time but figure I'm in the neighborhood of 75%+ attenuation. Over the course of the next 4-6 days get it up to 68 degrees. At about day 12-14 take a gravity measurement to confirm it is within a point or so of FG then begin cooling it down to 33 degrees where it stays until I'm ready to keg it. Haven't had an issue with diacetyl yet (knocks on wood).

 

[Jmash]

I'm in the 6th day of primary with a Vienna Lager. Yeast is Saflager 34/70. Terminal target is 1.015
OG was 1.06.
Reading today was 1.022
I'm planning on starting rest today. There is however still krausen cover. Should I wait?

 

[schatzke]

I recently did a vienna lager also. My gravity numbers were very close to what yours are at and thats when i started ramping the temp up to 65* for 2 days then brought the temp down to 36 and kegged. continued to lager for 30 days so far. my 1st lager and its yummy

 

[BlueHouseBrewhaus]

I'm in the 6th day of primary with a Vienna Lager. Yeast is Saflager 34/70. Terminal target is 1.015
OG was 1.06.
Reading today was 1.022
I'm planning on starting rest today. There is however still krausen cover. Should I wait?

You're right at the perfect place to do your D-rest. Ramp it up in the 63-65 range and give it a few days. Be sure the gravity is at FG and ramp down to lager. You're good to go.