Lager diacetyl rest timing???

My Maibock has been fermenting at around 49 F for about three weeks and is slowing down considerably but it is still fermenting. There is still a thin layer of Krausen on top of the beer.

Should I go ahead and warm up to 58 F for the diacetyl rest? (Per Wyeast website info on Bavarian Lager yeast 2206)


Thanks,
Al

Well, I usually do the d-rest when fermentation is about 75% done, so you can check the SG. While you're checking the SG, taste it. I've had several beers using Bavarian lager yeast that did not require a diacetyl rest. If you taste any diacetyl, or perceive any "oiliness" in the mouthfeel, it needs a d-rest. If you don't detect any diacetyl at all, I'd probably skip the rest. If you pitch cold and the ferment stays within temperature guidelines, or it stays in the primary long enough, sometimes very little diacetyl is produced.

Wow, what a quick response! Thanks.

Unfortunately, I don't have a thief so I can't pull a hydrometer sample without siphoning.

I pitched this beer from a healthy starter at ferment temps and it has'nt changed from that temp so do you think it would make any difference one way or the other if I did the diacetyl rest anyway. It won't hurt it in any way will it?

BTW I have a really untrained palate when it comes to tasting things like diacetyl. I'm sure I've tasted it before but i don't think I could identify it. I just go by the old : Tastes good / Tastes bad, plan.

Thanks much,
Al

Oh, no, if you're not certain, wait until fermentation is finished and then go ahead and do the diacetyl rest. I'm just too lazy at my house to do it if I don't need to. At my house, it involves moving heavy carboys into a different room, upstairs, etc. If you can easily just change the temp to 58 degrees, then it's fine to do it!

(A sanitized turkey baster is a great sub for a wine thief, for taking SG samples)

If you taste diacetyl you will know, its a buttery, butterscotch, or oily flavor.

You'll know diacetyl when you taste it. It's like a very chemically feeling butterscotch (or even scotch) like taste. It should be fairly obvious.

And you also get that slick, coating mouthfeel with diacetyl. That is usually the only way I can detect it.


TL

If you have an autosiphon you can take out the inner tube and plunger and use the outer tube as a wine thief to get a hydrometer (or taste!) sample