Diacetyl rest and fermentation

[Frodv]

Hi, can anyone explain to me how and when i should do a diacetyl rest on a light lager?
I've heard that a lager should be in the primary fermenter for about 3 weeks, and that you should do a diacetyl rest when expected F.G. is about 1.002-1.005 points away, but what if it (as it allmost allways does) get there way before 3 weeks?

 

[Yooper]

Hi, can anyone explain to me how and when i should do a diacetyl rest on a light lager?
I've heard that a lager should be in the primary fermenter for about 3 weeks, and that you should do a diacetyl rest when expected F.G. is about 1.002-1.005 points away, but what if it (as it allmost allways does) get there way before 3 weeks?

I've never left any beer in the fermenter for three weeks, at least not on purpose, but yes- a lager (or an ale for that matter) should definitely be finished before three weeks is up!

 

[Frodv]

I've never left any beer in the fermenter for three weeks, at least not on purpose, but yes- a lager (or an ale for that matter) should definitely be finished before three weeks is up!

OK, so could you explain to me step by step how to do a perfect light lager?
From pitching to diacetyl rest to cold crash to lagering.

 

[Revvy]

Here's a good thread with info on diacetyl rests. Preventing Diacetyl -or- "Hold The Butter Please"

 

[Yooper]

OK, so could you explain to me step by step how to do a perfect light lager?
From pitching to diacetyl rest to cold crash to lagering.

How I do it:

1.Use a yeast calculator (I like mrmalty.com) to pitch the proper amount of yeast needed.

2.Cool the wort to 48 degrees, and add the yeast and then allow it to raise to 52 degrees (or whatever my desired temperature is).

3. When fermentation slows down and the beer is about 75% finished, raise the temperature 10 degrees (usually 7ish days, but not always).

4. Once the beer has been at diacetyl rest temperatures for 48 hours or is completely finished, I rack and then lager at 34 degrees for 1 week for every 8-10 points of OG. So, for a 1.040 light lager, I'd hold at 34 degrees for 4-6 weeks.

That's about it.

I don't like the character imparted by a lengthy contact with the yeast cake, particularly in light lagers.

 

[BrunDog]

Yooper, what is that character? I keep hearing to get the primary off the yeast, which is contradictory to what I read for so long... That a few weeks will cause no harm. Trying to assess now what is the right timing. I know it should be based upon FG measurements, but I find myself too lazy to go pull samples every day or so, so just opt to let the beer go for 3-4 weeks on average, then keg/age (or rarely, secondary).

 

[Yooper]

Yooper, what is that character? I keep hearing to get the primary off the yeast, which is contradictory to what I read for so long... That a few weeks will cause no harm. Trying to assess now what is the right timing. I know it should be based upon FG measurements, but I find myself too lazy to go pull samples every day or so, so just opt to let the beer go for 3-4 weeks on average, then keg/age (or rarely, secondary).

It doesn't' cause harm- not at all! But there are flavors that are imparted by a longer contact with the yeast.

A while back, Basic Brewing Radio podcast did a triangle experiment where they did something like a traditional primary/secondary, a long primary, and I think a medium length primary with no secondary.

Then they taste tested with a panel. Preferences were about evenly divided, as some really preferred the flavor of the beer that came from a long primary but just as many preferred the short primary.

Try it yourself. Maybe split a batch in half and see which YOU prefer. I have done that, and my preference is definitely not the ultra-long primary, particularly with lagers that are "crisp" and without yeast character.

It won't create things like autolysis to have a long primary, which was the fear pounded into us 10 years ago or so. But there are flavors involved. Some find that a plus, some do not. It's up to your taste to see which is your preference.