Cold Crashing and Priming Sugar

So, I'm looking at priming sugar calculators and they compensate by using less sugar in colder beer due to more dissolved gas in solution. Makes sense.

My question. Say you cold crash a beer. The calculators out there want you to use about half as much sugar at near freezing temps than you would use at room temp to reach the same carbonation level. That beer is picking up minimal gas if its not being shaken, correct? It would be correct to use fermentation temps in the calculator rather than the temp of a beer chilled post fermentation? I've always used around 4oz of corn sugar in a 5 gallon batch and had nice carbonation levels. I'm assuming this to be the case or our beer would end up a oxidized mess due to oxygen pickup during cold crashing (there's only so much co2 in that headspace).

As a follow up to that. Would a beer cold crashed for weeks ultimately begin picking up gas working towards equlibrium, much like a beer takes a couple weeks on CO2 to carbonate? Would you risk suckback of oxygen and an oxidized beer by cold crashing for long periods of time in a bucket or carboy simply fitted with an airlock?

Inquiring minds would like to know..

I posted the same thing once. I brewed an ipa and cold crashed. The calculator said to use about half the amount of sugar. Months later and there was hardly any carbonation. Don't adjust the temp down to cold crash temp on the calculator.

The temperature you use in the calculators it the temperature the beer was when the last of the fermentation occurred. Your beer doesn't automatically absorb more CO2 because you cooled it. There isn't any more CO2 being produced for it to absorb.

RM-MN said:

The temperature you use in the calculators it the temperature the beer was when the last of the fermentation occurred. Your beer doesn't automatically absorb more CO2 because you cooled it. There isn't any more CO2 being produced for it to absorb.

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Would it absorb gas from the ambient air if it sat for a period of time, or would you need to agitate the beer for that to occur?

Bamsdealer said:

Would it absorb gas from the ambient air if it sat for a period of time, or would you need to agitate the beer for that to occur?

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No, just as a flat soda would never become carbonated again by just letting it sit around for a period of time. Not certain I know what you mean by 'agitate' but the only way to get CO2 back into the beer is to force it in or to get yeast to create more.

Well, a degassed liquid wouldn't carbonate if agitated or shook up, but it would absorb gas until it reached equilibrium with the pressure of the atmosphere around it.

I guess I assumed by 'gas' you meant CO2 specifically but it sounds like maybe you're talking about oxygen?

Any gas really. The thinking was that an airlock wouldn't create a seal and would allow ambient air, which is 21% oxygen or something like that, to enter a carboy and oxidize a beer. Basically, would cold crashing a beer for an extended amount of time, weeks say, result in an oxidized product or would dagassed liquid tend to stay degassed as long as it's not shook up?