Cold crashing sucks

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colm89

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But how do you prevent it?

Brewed a batch last week (first batch in my new brew bucket mini with a blowoff tube), and foolishly cold crashed it without thinking, only to find it had inhaled about a litre of star san. I couldn’t consciously give this to anyone and it tasted funky, so I poured it down the drain. For the record, this is the third batch I have cold crashed, but previously done it in carboys with an s type bubbler airlock and was blissfully unaware of negative pressure.

This suck back experience of course sent me down the rabbit hole of oxidation, Mylar balloons etc etc, and today I started a cold crash with a starsan soaked rag covering the airlock hole, knowing it may well oxidise the batch.

What I am curious to know is how the experienced home brewers cold crash before bottling, without a mylar balloon, and without a pressure fermenter/keg. Or do you just forego that step altogether and allow the remaining yeast to drop out in the bottle?
 

jeg3

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I've only ever cold crashed once and that was my one and only lager. I don't ferment with an airlock or a blow off tube, but I did seal the lid prior to lowering the temp on the fridge. No problems
 

Cwrw666

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Only ever cold crash wine. No fridge necessary, well not in our house anyway.
I don't use air locks with FVs so suckback is not a problem. With regards to oxydation - not really a problem as the fermented brew is chock a block with dissolved CO2 which it is slowly releasing and providing a CO2 blanket on your brew. Just don't slosh it around!
 

darrellm

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I have 2 FVs one lid with an airlock hole the other without, and swap the lid on the one fermenting with a solid one at the end of fermentation: when it stops bulging it tells me that fermentation is over and I can move it somewhere cool for 24-48hrs.
 

Galena

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I have only cold crashed twice, the first I just put the lid on tight and let it contract, the Speidel FV's are very tough so whilst it did collapse a little it was not permanent, but it did not suck any air in.
The second time was with a Czech Pilsner and I just had an inline empty vessel in the blow-off tube, that contained the CO2 and allowed the starsan to be sucked up without reaching the FV.
 

smcc

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Blowoff tube is really for use during peak fermentation with yeasts like weißbier that are highly active I would switch it to airlock before crashing. Sorry to hear about your brew though. I personally will always drop down temp prior to dry hopping as you want to avoid any yeast activity as hop enzymes can also help break down dextrins
 

An Ankoù

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Cold crashing is easy at this time of year. I don't use airlocks any more and I've never used a blow-off tube (except after a chicken phaal) instead I put a bit of rolled up kitchen paper in the bung hole. I ferment in one room which is constantly at about 17C and I rack into secondary with a bit of ascorbic acid to take up the oxygen in the head space. If I want to cold crash, I move the vessel into an adjacent, unused room which is a few degrees less and I can get it down to around 10 C if I leave the windows open overnight. While I like to have a lot of headspace in my primary fermenter, I like to have as little as possible in the secondary so suck back is minimised. In any case, there's enough residual antioxident in the beer to cope with this and hopefully with bottling, too. You don't need to chill the beer in a fridge to get it to drop bright, just a sudden drop of a few degrees is enough. I think it's the suddenness/shock of the temperature change that encourages the yeast to fall out of suspension.
 

Buffers brewery

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I’ve always cold crashed during my short brewing career as I bought a fermentation fridge from the start, mainly to control fermentation temperature. Just used a bubbler until I had a particularly vigorous fermentation causing a bit of a gusher. It coincided with me reading about CO2 capture and balloons so switched to that. Haven’t noticed any difference in my ales but I enjoy playing with the extra kit :laugh8:
 

Spit

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All very interesting right or wrong I've been taking my brew out of my heated fridge the night before bottling just to get the hop crud to fall to the bottom to make syphoning less of a headache. Any comments on this practice would be welcome.
 

dave_77

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I have one of these valves that seem to solve the problem. I don't use it much now as I use my fermzilla under a little pressure but i still use buckets for saison's so I use the valve then when cold crashing..always end up with the full volume of starSan in the airlock.
 

Scottyburto

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Is it that you are cold crashing too fast? Therefore the liquid is contracting quicker than it's releasing co2?
I've been putting my FV outside and the liquid is still in the airlock a few days later and the temp has definitely dropped with the beer clear. I gently swirl the FV before leaving it and I know this agitates the co2 as the airlock activity starts up. This was more a practice I started to circulate the dry hop more than anything else. It's known that dry hop can restart a bit of fermentation so perhaps that's balancing it out for me. FYI I'm not a big dry Hopper only 40-60g or so.
 

Alan_Reginato

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Use S shaped airlocks. Or just take it off from the fermenter. Maybe just empty it. Not a big issue let some cold air inside. Should still have a co2 blank on the top of beer.
 

Coffin Dodger

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I’m not really familiar with what you people call cold crashing. I ferment in an open-topped home-made cylindriconical vessel, and rely on the yeast layer which forms on the surface to prevent oxidation and air infected spoilage. When the gravity has fallen to about 14 I cool it down from 19C ish to 6C by means of a Maxi cooler and external water jacket, which takes around 12 hours – hardly ‘crashing’!

I then skim off most of the yeast head, being careful to leave a protective cover on the surface, which stays there until the fermentor is emptied. On the odd occasion when the head has disappeared, I kept air away by floating a circle of bubble wrap on the surface. I don’t think I have ever fermented under an airlock, even in the far off malt extract days.
 

Leon103

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I have one of these valves that seem to solve the problem. I don't use it much now as I use my fermzilla under a little pressure but i still use buckets for saison's so I use the valve then when cold crashing..always end up with the full volume of starSan in the airlock.
Any reason you use buckets for saison?
 

Zephyr259

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I just started a cold crash yesterday, set the inkbird to 3c and remove the blow off tube from the liquid and cover it with sanitised foil is all I do. I once forgot and sucked a few hundred ml of sanitiser into the beer which survived just fine. An test that Experimental Brewing did showed that it might just mute the hop aroma of the beer, which would make sense as my california common had no hop character. They were testing it because you can be left with a bit of sanitiser in a keg if you fill with sanitiser then blow it though with CO2 to purge the keg.

My learning from this was to use less liquid for the tube and to use cooled boiled water instead of sanitiser, I do sanitise the jar the water goes in.
 

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