Cold Crashing Avoiding Oxygen

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mitchar19

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I just wanted to see what everyone does for cold crashing. When I first started cold crashing I used to leave my airlock on and put the beer in my chest freezer for about a day. My initial concern with this is I was sucking in oxygen into the beer as I was cold crashing. More recently I have been taking off my airlock and tightly securing freezer bags over the mouth of the carboy while cold crashing to try to avoid oxygen being sucked in. I'm not sure how affective this is. Now I'm thinking what if I transfer my beer from primary to a keg under co2 and cold crash the beer in the keg and then transfer it to a final serving keg. I know this is a lot more work and I'm not sure if it's going to be worth the effort. Any advice or thoughts? I would like to know what some of the people making great award winning beer do.
 

hoppymonkey

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I just leave my lock in and full of vodka. The temp change is so small that it doesn't suck much in .
 

rockfish42

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Did you actually notice oxidation in beers that were cold crashed in carboys? You could always replace the airlock with a piece of foil rubber banded on.
 
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mitchar19

mitchar19

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Honestly I'm not sure I noticed oxidation. I just noticed that I seem to lose some hop aroma and notice a flavor that I can't put my finger on but kind of reminded me of the smell of the freezer that I cold crashed in. I don't know if that makes any sense but that's the best way I can explain it.
 

carrolte

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mitchar19 said:
I just wanted to see what everyone does for cold crashing. When I first started cold crashing I used to leave my airlock on and put the beer in my chest freezer for about a day. My initial concern with this is I was sucking in oxygen into the beer as I was cold crashing. More recently I have been taking off my airlock and tightly securing freezer bags over the mouth of the carboy while cold crashing to try to avoid oxygen being sucked in. I'm not sure how affective this is. Now I'm thinking what if I transfer my beer from primary to a keg under co2 and cold crash the beer in the keg and then transfer it to a final serving keg. I know this is a lot more work and I'm not sure if it's going to be worth the effort. Any advice or thoughts? I would like to know what some of the people making great award winning beer do.
i have also noticed the tendancy for my carboys to vacume suck the ailock. it seems like a bad deal. speacially when im bringing the primary from 80 to 70 in the fridge before pitching yeast and i have tap water sucking back in. it really make me uneasy.
 

Germelli1

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This is exactly why I don't cold crash. Unless you do it in a keg, you are sucking in outside air. It doesn't matter how you seal it up: Airlock-suck back regardless of S-type or 3-piece (vodka or star san would not sanitize air passing through); if you use foil or saran wrap, etc it just lets the air in the crevasses.

I will use foil on starter flasks or ferment in unsealed buckets all day, but that is when C02 is being off-gassed.

I am not one to be overly paranoid about sanitation, but intentionally sucking room-air into the fermenter does not seem wise to me.
 

emjay

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On eof those airlock-free silicon stoppers (that have little flaps to let air out under pressure) would probably be the best way to deal with this, though it would create a slight vacuum.

I've also seen people use a sort of balloon or bag (filled with CO2, sometimes collected from the actual fermentation itself) attached over the airlock, so that when it sucks in air, it only takes in CO2.
 

Nightbiker

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first, CO2 is heavier than air. If you fermented in the carboy, the yeast have filled the 'void' with CO2 anyway (which displaced the oxygen as the carbon dioxide was out-gassed from the yeast and subsequently, beer), so what little air may get sucked in would not be involving itself in your beer anyway. At least no more than would when you draw the beer out of the carboy and put it in a bottling bucket for priming (if you keg, you could minimize this by purging the keg with CO2 first). But seriously, the minute amount of air that MAY hit your beer is certainly not worth all of this anxiety. If you bottle, do you use those oxygen-absorbing caps? (just wondering)
Anyway, in answer to the original question, sometimes I cold-crash in the keg, sometimes in the fermenter -depends on my mood, and if I need the fermenter to put fresh wort in, or really just how lazy I am at the time. :)
 

remilard

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first, CO2 is heavier than air. If you fermented in the carboy, the yeast have filled the 'void' with CO2 anyway (which displaced the oxygen as the carbon dioxide was out-gassed from the yeast and subsequently, beer)
This seems to be the common homebrewer understanding of the physics governing the diffusion of gases. We would all be dead if this were true, however.
 

Hex

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Here's what I have done. One hole stopper, top section of plastic racking cane, Ziploc freezer bag, CO2 in bag.

 

Germelli1

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first, CO2 is heavier than air. If you fermented in the carboy, the yeast have filled the 'void' with CO2 anyway (which displaced the oxygen as the carbon dioxide was out-gassed from the yeast and subsequently, beer), so what little air may get sucked in would not be involving itself in your beer anyway. At least no more than would when you draw the beer out of the carboy and put it in a bottling bucket for priming (if you keg, you could minimize this by purging the keg with CO2 first). But seriously, the minute amount of air that MAY hit your beer is certainly not worth all of this anxiety. If you bottle, do you use those oxygen-absorbing caps? (just wondering)
C02 is heavier than air, but when you start getting air currents from pressure differences, you can't predict where either gas would be (C02 and air).

I am not saying everyone who cold crashes is automatically doomed, it is just something that makes no sense in my head so I personally don't do it! Cold crashing in a bottle individually just makes more sense. Sure I may get a little more sediment, but with most of my favorite yeasts, it compacts like a rock anyway.

And I use 02 absorbing caps on most beers that aren't session beers. But I always "mock-purge" the bottles by allowing the C02 in suspension to work out of the bottle for about 10 minutes after filling before sealing the cap down!
 

drawdy10

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you guys have covered everthing except how to get the airlock to not suck back into the carboy when you cold crash, this is especially easy when you cold crash in plastic carboys i have noticed. Would it be best practice to remove the airlock before cold crashing and replace with a solid bung or carboy hood?
 

JasontheBeaver

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But I always "mock-purge" the bottles by allowing the C02 in suspension to work out of the bottle for about 10 minutes after filling before sealing the cap down!
I've heard others waiting 5-10 minutes after filling a bottle before capping. Doesn't this release a lot of carbonation and consequently make your beer flatter?
I have the understanding that as long as you're capping on foam you should cap as quickly as possible to prevent excess CO2 from escaping. There should be no O2 in the bottle because the rising liquid (which is topped with a thin cap of foam) forces it out. Am I wrong here?

Oh wait, I am talking about beer that is force carbed, are you talking about bottle conditioning?
 

eastoak

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This is exactly why I don't cold crash. Unless you do it in a keg, you are sucking in outside air. It doesn't matter how you seal it up: Airlock-suck back regardless of S-type or 3-piece (vodka or star san would not sanitize air passing through); if you use foil or saran wrap, etc it just lets the air in the crevasses.

I will use foil on starter flasks or ferment in unsealed buckets all day, but that is when C02 is being off-gassed.

I am not one to be overly paranoid about sanitation, but intentionally sucking room-air into the fermenter does not seem wise to me.
worried about nothing. people have been cold crashing beer for a very long time. would we have lager without cold crashing? whatever cooties may come in with a little air has to contend with a blanket of CO2 and alcohol, good luck with that. i left an uncovered gallon of fresh wort in my garage to see how long it would take for it to get contaminated with wild yeast or some bacteria...2 weeks later all it had was a bit of furry mold but the wort was still sweet. not saying that anybody should change what they are doing i just think it's important to dispel myths and irrational fears.
 

el_caro

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Thousands of brewers in Australia use plastic wrap instead of lids on their large mouth fermentation vessels. Many remove the plastic to dry hop then replace it. Never heard of infection issues. I think there is some real paranoia about a bit of air entering through an airlock on change of pressure in the fermenter.
I cold crash using an airlock filled with Starsan solution and never have had an issue.
 

drawdy10

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Well it says vented so you should be fine! I have used an orange carboy cap with success and I also have used an undrilled carboy stopper which created a pressurized carboy which I am surprise it did not blow because when I went to keg I pulled off the cap and it flew to the ceiling and the beer started foaming up. So don't use the undrilled carboy stopper, go for vented or use the carboy cap. Cheers!
 
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