Newest Threads

greyfox_21 · 11-30-2012, 02:16 AM

When is the optimal time to do a diacetyl rest for a lager. I have done an extract recipe where I did not do a rest at all and did not have any off flavor of diacetyl and done an all grain where I have done a diacetyl rest for the last 2 days of primary fermentation and have had substantial diacetyl flavor. Thoughts? Maybe I have done something else wrong during the process to have left over diacetyl in my beer.

**501irishred** · 11-30-2012, 02:36 PM

"By the book" you followed a good process for your ag batch. Depending on the yeast strain used, a rest may not be "required", and some may need an extra day or two. What temp did you use for your rest, and how did you lager afterwards?

**TopherM** · 11-30-2012, 03:10 PM

Ideally, you are supposed to do the D-rest when you have reached 75% of FG. For example, if your OG is 1.05 and your expect FG is 1.01, then 1.05-1.01=1.04; 75% of 4 gravity points = 3; 1.05 - 1.03 = 1.02; So you would do the D-rest at 1.02. 48 hours at 70ish, IDEALLY ramping up from your fermentation temp to 70ish at about 5 degrees/hour, then following the D-Rest, ramping down to lagering temps at about 5 degrees/hour.

When I do lagers, I generally follow those rules, but I'm pretty lax about getting everything perfect, and my lagers turn out great, but ideally, that's what the procedure would be. As a benchmark, 75% FG is generally right about when you start to notice the fermentation slowing down as far as airlock activity.

greyfox_21 · 11-30-2012, 05:09 PM

Quote:

Originally Posted by 501irishred

"By the book" you followed a good process for your ag batch. Depending on the yeast strain used, a rest may not be "required", and some may need an extra day or two. What temp did you use for your rest, and how did you lager afterwards?

I used WL Octoberfest yeast and the rest was done at 68F. I know the rest should be at a higher temp but my basement does not get that warm in the summer time and I do not have the equipment to raise the temp. I lagered at 45F for 4 weeks and kegged at 42F for 3 weeks.