"Poor attenuation through loss of yeast in blowoff?

[EkieEgan]

I do know this was asked before. I did read what was posted from 2009, but I am wondering if anything new has come to light?

I have 2 beers that as far as I am concerned, did not attenuate out. Both beers had extremely violent fermentations. One, a saison that I put on top of a yeast cake (propagated Ommegang Hennepin), blew my airlock off and spewed yeast up onto my pantry ceiling! I had to add a 1.25" hose directly into the fermentor. As of now, the reading is 1.008 The previous beer dropped to 1.002 and the mash and ingredients are similar. The second, a small RIS started at 1.085 and fermented like mad using WL007. I lost probably close to a gallon through the same BIG HOSE lol..it is only at 1.029, which measures 65% app. att. I expected at least 75% out of this yeast and grain bill. I just added yeast from another WL007 starter in the hopes that it may take back off? It's not the end of the world in either case, but I was wondering if anyone else has had similar experiences with such a loss of krausen?

 

[EkieEgan]

Well I kinda answered my own question. Pitching fresh yeast into the RIS started refermentation so that's good. It should help it to drop a few more points. The saison? Maybe I could have tried something similar? It got bottled at 1.008 It's not the end of the world. Hopefully it is still perceived as somewhat dry.

 

[ncbrewer]

I'm glad fermentation restarted. I've had what could have been similar experiences, but don't really know if kraeusen blow-off was the cause. For a while in the 1990's there was a recommendation by some to use a carboy with very little head space to encourage blow-off - to get a cleaner flavor, I think. That seems to have died out - due partly to a concern about loosing yeast cells. So IMO, your concern seems to be valid.

 

[EkieEgan]

I'd never heard that about leaving little head space. A different approach I guess. I honestly sparged too much or should have boiled more off. My OG would have been higher and I would have had more room in the carboy. I made a 2L starter. Maybe that isn't enough? Maybe the yeast got fatigued? I guess covering all of the "what it's" would be prudent. Thanks for the reply!

 

[uwmgdman]

I can vouch that batches with blow-off do not lessen attenuation. It is a sign of a very healthy fermentation. I'd say 60-75% of my batches blow-off. Every batch I brew gets a tube into a tub of water until high krausen passes and I know with certainty it can be replaced with an airlock. Attenuation is mainly going to be driven by yeast strain selection and fermentability of the wort.

 

[EkieEgan]

I probably didn't have enough healthy yeast. Maybe a 2L starter isn't enough for a 1.085 beer? As far as can tell, the saison just finished at 1.008 It went on top of the yeast cake and went like wildfire. No worries..it's all a learning experience. Thanks for the info.