I’m not certain why I began thinking about this, but I’m hoping to find an answer nonetheless. Many years ago, I had a kraeusen layer on my starter that actually blew the top off a 2,000 mL flask (the starter itself was about 1,300 mL). However, it has never happened before or since. In fact, I barely even get any foam at all.
Is it normal to NOT have a kraeusen layer in the starter? And is there an explanation?
I add the DME (I use a light DME) to my regular tap water before the water boils to prevent boil flare up and I wait until my wort is cooled to 72 degrees F before adding the yeast. I drop in my sanatized stir bar and away we go! I typically pitch my starter between 24 and 28 hours after making. And I have solid fermentation activity in my beer within 12 hours after pitching the starter.
Funny you should mention it. I’ve always assumed that you don’t see a kräusen head on a starter for a couple of reasons. One, it’s such a small scale, quick fermentation. Either it’s not enough activity to raise a big head or you just miss it. But you’d see the “bathtub ring,” wouldn’t you? And on a stir plate, you’re continually knocking it down and reincorporating it. But there was one time for me, too… I was growing up some decidedly top cropping yeast from a bottle of commercial beer, and that really did escape and ended up all over the place… I look forward to answers, too!
I generally don’t see any kräusen on my single-stage starters, although I have a couple of times. If I do a two-stage starter I usually see a pretty significant head of foam on the second stage even if I didn’t see any on the first stage. I assumed it was a combination of more yeast and a smaller surface area as the flask is filled to the narrower part.
I usually see a little foam on top of my (stirred) starters, but never a true krausen, as it doesn’t have any yeast gunk in it. I think Robert is right about the stirring, which would prevent, or at least minimize, the accumulation of a true krausen in a stirred starter.
The only time I’ve ever had a true krausen on a stirred starter was when, overnight and unbeknownst to me, the starter stopped stirring, as the stir bar moved off the center of the flask bottom and was pinned against the side. So a krausen formed, and of course as soon as I moved the flask it gushed everywhere as the CO2 suddenly broke out of solution. Perhaps this happened that one time with you?
Funny you should post this today. I put a starter on the stir plate yesterday and this morning it had more than 2" of krausen on it. I used Fermcap-S too. With probably over 100 starters under my belt, I don’t remember ever seeing more than 1/4" before.
I am going to weigh in on this as well. I have always use a stir plate with my starters (sorry Denny that you can’t find yours ;D ). I make my starters the day before I plan to brew and always see a small amount of krausen on top of the wort after a few hours or so. It falls back into the starter liquid overnight and I have a nice healthy cloudy starter the following morning as well as the proverbial “bathtub ring” Rob has mentioned. Some people refrigerate their starters, decant the fermented beer, add chilled wort from their batch, and put it back on the stir plate. I used to do this but now just pour the whole starter into the fermenter as it is more time efficient for me.
If I am using a really aggressive yeast, the krausen will sometimes get high enough to push the pre-sanitized sponge out of the flask. I have resorted to using larger volume flasks to alleviate this problem.
That’s interesting. I use mostly WLP-001 or WLP-007 and pitch a 500 ml stock starter into two 1L pitching starters in 2L flasks. These go on the stir plates, and I will have krausen within an hour or two. If I leave them on the stir plates overnight they will foam over, so I use the stir plates to control their fermentation rate, and turn them off when the krausen gets over 2/3 up the inside of the flask. The starters will usually finish out (little to no krausen) within 24 hours.
I have never encountered the situation that you describe!
That is curious indeed. Since the very point of a stir plate is gas exchange, as well as deterring flocculation, it should (as in my experience) prevent formation of a head. I’m also curious about Charlie’s procedure. But whether I boil in the flask with Fermcap-S and use a stir plate, or just put separately prepared wort in a gallon jug and oxygenate, I always use nutrient, and have only the one time had significant (problematic) kräusen in a starter/ propagation. I can’t say strain, even ale/lager, makes a difference – except that one time apparently. BTW that one time, I was culturing from a bottle of SNPA.
All starters are 100 g/L Briess light dry DME (aprox 1.042 SG). I don’t use any yeast nutrients or fermcap.
I prepare four 500ml stock starters from a yeast packet, and crash them when they finish out. Two days before I brew the pitching starters are prepared using 2L of fresh starter wort, and the 500ml stock starter is decanted and dispersed into them using the stir plate.
I don’t have any experience using fermcap, but that might be why you don’t get any krausen.
I only use the Fermcap when I boil right in the flask. When I do a larger starter, or second step, I prepare the wort separately, usually without Fermcap, and pour it into a large jug, but still usually don’t see much kräusen. Except that one time… I’m starting to suspect there’s another factor here that’s escaping us.
Always! They behave exactly like the 1L starters except on a smaller scale.
When I had a yeast bank (long story) and prepared starters from a slant I boosted it in 5 stages:
5 ml inoculated from the slant.
25 ml
125 ml
500 ml
2000 ml
I saw krausen in every stage from the smallest on up. I have a pic of one set of 5 ml stages where I captured the yeast from Bells 2-Hearted and Parish Ghost In The Machine. How the heck do I attach an image?
If you have an image on Google drive or the like you can post us a link. You see I’ve finally broken down and installed Tapatalk, which is a dead easy way to share images it turns out. (I’m just a Luddite.) Otherwise you need to have your image on a 3rd party hosting site.
Got the pic! But here’s the question now. Is that really significant kräusen? I mean, given a different geometry, like the surface to volume ratio of a flask, that amount of foam would be nearly nonexistent, right? But that would still be consistent with increasing kräusen in each stage.
Further, there is no stir plate to knock down the kraeusen. I would be willing to bet, after reading some replies posted here, that a 1200 mL starter without a stir plate will also generate a very nice kraeusen within a 24 hour period.