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Brews & Views Bulletin Board Service * Brews and Views Archive 2005 * Archive through February 06, 2005 * Yeast Activity Post-Krausen < Previous Next >

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Junior Member
Username: Nomad

Post Number: 46
Registered: 07-2004
Posted on Friday, February 04, 2005 - 04:55 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

My typical primary MO is to let it ride out and sit for awhile, and then check OG 10 -14 days after pitching. Typically no problem hitting my FG's. Recently, out of restless curiousity I've been checking gravities on an ale batch (1.056 with Wyeast 1272 @ 67-68F) and its slowly dropping toward its destination though the krausen fell about a day ago. And doing the same hyrdometer dance with my second lager batch (1.086 with WLP810 @ 59F), which is also slowing coming down to its intended FG, though its krausen fell more than a week ago. Both were mashed 151-152F at 1.3 qts/lb.

How many or few gravity points can yeasts (both ale and lager) go down after the krausen has pretty much dropped out though a fair amount of the yeast is still in suspension? Just curious, not worried about my brews.... yet.

Junior Member
Username: Qceps

Post Number: 97
Registered: 11-2004
Posted on Friday, February 04, 2005 - 06:41 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

It could depent on a lot of things, but, hypothetically speaking, if you used a lager yeast at low temperatures in a weakly hopped brew with a lot of adjuncts, you could have a very light krausen altogether. Also, your protein profile could be such that you have virtually no head retention, so the krausen could subside relatively quickly, but the fermentation would be nowhere near complete. Remember, krausen is not "just sitting there" - it is an equilibrium of bursting and newely created bubbles and could be shifted toward disappearance sooner or later.

Bill Pierce
Username: Billpierce

Post Number: 2142
Registered: 01-2002
Posted on Friday, February 04, 2005 - 07:11 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

I don't think Fredrik (by the way, where is he lately?) could have said it better, and I mean that as a compliment, q-ceps.

Geoff Buschur
Advanced Member
Username: Avmech

Post Number: 560
Registered: 06-2004
Posted on Friday, February 04, 2005 - 07:17 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

q-ceps could say it in few enough words that my eyes didn't start rolling toward the back of my head and my eyelids didn't start blocking the line-of-site to the computer monitor.

Advantage: q-ceps

Junior Member
Username: Nomad

Post Number: 47
Registered: 07-2004
Posted on Friday, February 04, 2005 - 07:58 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Cool, very succinct. So if I'm reading you correctly, q-ceps, it mainly depends on the protein profile of the grain bill that created the wort? That makes sense with regard to my ale, its an altbier hopped to 35 IBU (style guidelines, yadda yadda yadda....) and all of the alts I've experienced sucked in the category of head retention.

Also, lager yeasts are also known to plod again with little krausen, correct?

Fascinating. I'm sure (sure!?) patience will push my gravities down as they always do. Just fun to learn some new stuff. Thanks for the word.

Denny Conn
Senior Member
Username: Denny

Post Number: 4172
Registered: 01-2001
Posted on Saturday, February 05, 2005 - 09:14 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

If your alts lack head retention, you need to do something! I've come up with a new alt recipe that's damn close to Zum Uerige, and pours with a fluffy 2 inch head and lace all down the glass. It can be done!
LIfe begins at 60...1.060, that is.

Senior Member
Username: Fredrik

Post Number: 1964
Registered: 03-2003
Posted on Saturday, February 05, 2005 - 11:19 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

I just came home from 4 days work in munich and just booted the PC. Haven't yet catched up with emails and threads. I tried a few more new beers too. Probably write more on that later but the bad news is I have more work trips coming up (unfortunately not to munich again) so it will probably take a while before I'll catch up with things in cyberspace.

Using opaque fermentors I never payed attention to the visual apperance of the beer during fermentation (krausen/foam level), but it's clear that the fermentation as such has different phases. Like, after the initial lag, fermentation activity does accelerate to a certain point (the peak), after that yeast growth slows down (not stops) and a certain % of the cells start to go dormant, and there is an apparent deacceleration of the fermentation activity but the occurence of the fermentation peak, is only some midway through fermentation, and once the peak passed there is still a *significant* amount of fermentation work left to do, not only a few points. Also the exact position of the peak %-wise would depend on many things, like wort composition and pitching rate etc.

Like qceps wrote, how the visual level of the krausen/head correlates to fermentation activity is probably quite indirect.

I personally like to look at the bubbling as an indicator of activity and while it has some slight issues to correct for, like ambient pressure, temp changes, solubility and supersaturation, but that is IMO relatively managable.

My guess is that to correct for fermentation activity to - foam level is alot more complex and chaotic than the bubble counting will ever be. For example, I don't know what fallback of krausen means in terms of fermentation activity? I suspect it would probably swing alot from case to case.