Just wanna know how I should end a diacetyl rest for the pilsner I've got going. I've transferred it to a new carboy after 2.5ish days at about 67-68 degrees. I'm assuming that I would slowly bring it down to lagering temps (maybe a degree an hour?). Or should i just throw it down to lagering temps without worrying about it.
When I'm done with the diacetyl rest I keg and crash to lagering temps as fast as the fridge will take the temp down. Some will say you should do it gradually. I don't believe that's necessary, as long as the yeast have finished their work. I believe the gradual temp reduction advice goes back to the days before elevated diacetyl rests, where diacetyl cleanup and even some attenuation was happening at lagering temps.
Depends who you listen to, but I would say the timeframe for STARTING the diacetyl rest and racking is much more important (and sometimes harder to gauge)
I don't bottle anymore (except from already carbonated kegs), but if I did I would probably still crash. It doesn't hurt the yeast, and the ones that remain in suspension should be fine for carbonating at higher temps when the time comes. I'd be more concerned about how many (how few) cells are still in suspension rather than how healthy they are. Having said that, plenty of people have reported successful bottle carbonation after lagering.
Here's what I do, and I'll tell you why. When specific gravity points reach half the original gravity points (e.g., 1.060 goes to 1.030), then warm it up. Then, keep it warm until fermentation is complete. When fermentation is complete, wait a few more days just to make sure things are all cleaned up and finished and ready to roll. Then crash chill it as fast as you want. Lager in bulk for a while if you want, or don't. Then bottle or keg. There is no detrimental flavor impacts with keeping things warm for a brief time (a week or two) near the end of fermentation. In fact it might help far more than it hurts anything. Most of the flavor compounds from fermentation happen in the first 2 or 3 days. This is true for both ales and lagers, assuming you pitch enough yeast in. "They" say you should do a diacetyl rest when fermentation is about 2/3 complete. Assuming 75% apparent attenuation typical of most lager yeasts, this happens at 2/3 times 3/4 = 6/12 = 1/2 of original gravity points. Whether you need a diacetyl rest or not, the benefits of such a rest are: elimination of diacetyl, sulfur, hot alcohols, acetaldehyde... you name it, it gets reduced the warmer it is, through either yeast metabolic process, or in the rare case of acetaldehyde, through the increase in temperature itself since this chemical has a vaporization point of 68 F. So, warm 'er up, keep 'er warm for a bit. And then, when you're sure everything is totally done and clean, chill 'er down and do what you want. I find bulk lagering for about a month is helpful for the cleanest lagery flavors. But, you can also do this in the bottles with decent results. No need for any temperature ramping... I really don't know who came up with that idea or why, but it makes no sense to me. Maybe it makes sense to someone else. I don't know. Do what you like. Cheers.
