cold-crashing

[Nicasio Tom]

For my single-stage fermentation in a temp-controlled refrigerator, I ran a blow-off tube from the carboy into a container of Star-San solution. The tube worked great during a vigorous fermentation. I kept the blow-off tube in place, and after fermentation stopped, I dry-hopped for a few days and then cold-crashed to 38º. Stupidly, I didn't think it would, but the pressure differential sucked about a half-gallon of the sanitizer solution into the carboy. Not good. I dumped the batch. What should I do next time? Use foil? How serious is the risk of O2 in late fermentation? – Nicasio Tom

 

[McMullan]

Avoid O2 exposure at this stage. Use less StarSan solution; 2-3oz is enough. Use a blow-off tube if expecting mess. Otherwise fit an airlock when fermentation is almost done. Loosely fitted foil until then. (Unless fruit flies are in season, as they are here at the moment, when I fit an airlock from the start.) A little StarSan solution in a small container inside a larger blow-off container. I'm not a fan of "cold crashing". We only need to drop temperature several degrees (C) below fermentation temperature. Cellar temperature for ale yeast and fridge temperature for lager yeast. Best dropped slowly, over a day or two, to reduce the differential and, counter intuitively, promote more efficient flocculation.

 

[Kevin58]

Been there done that. I tried cold crashing once and the same thing happened. I researched and found all kinds of DIY contraptions to prevent this but in the end decided to just skip that step. My homebrew philosophy is to eliminate unnecessary steps and to me this is one of those.

 

[Nicasio Tom]

Thank you, McMullan and Kevin. I am happy you take a dim view of cold-crashing, as I have one less worry while simplifying the process! Cheers.

 

[McMullan]

Just to clarify, the temperature driven differential here risks creating negative pressure (a vacuum) inside the FV. By lowering temperature slowly at the end of fermentation, residual yeast metabolism limits a pressure differential building up and allows the yeast cells to remain active enough to express flocculation behaviour. If the temperature is crashed rapidly and goes below the limits of yeast metabolism, yeast cells enter "shock" and shut down, metabolically, and the cells remain suspended in solution with flocculation behaviour (cell clumping) being down regulated then ceasing so that gravity takes much more time to clear the beer. It's one of the wonderful things about living things, biology, where "2+2" equals >4 and less = more. Where yeast seem to break our laws of physics. Keep it simple, it's only beer.

 

[GigaFemto]

I lower the temperature of my beer slowly, so not a cold "crash" but cold conditioning, down to 34 F for a couple of days before kegging. I find that it makes a compact yeast cake that allows me to transfer clearer beer into the kegs. Dry hopping while cold also seems to work well. I use a mylar balloon on a tee between the fermenter and the blowoff jar to keep the pressure from going negative. The mylar balloon fills with CO2 during fermentation. Just before I start lowering the temperature I close a valve on the line to the blowoff jar but keep the balloon connected. That prevents any suckback of sanitizer from the blowoff jar. The balloon has plenty of volume to provide CO2 to compensate for the lowered temperature.

--GF

 

[Nicasio Tom]

GigaFemto,
Do you have a photo of this device?
Thanks.

 

[Kevin58]

FYI I don't hold a dim view of cold crashing. Many people do it and it can be a useful process. I just choose to put my time and energy into other areas. It all boils down to personal preference. If it works for you and you derive pleasure doing it then by all means do what you like.

 

[Kevin58]

GigaFemto,
Do you have a photo of this device?
Thanks.

 

[Nicasio Tom]

Thanks for the illustration, Giga. And, Kevin, I appreciate your point of view. Much to be learned in this forum. Kudos to Beersmith!