Priming sugar with cold crashed beer. why use half as much sugar?

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Brewmex41

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I got brewers friend on my android. When I changed the field for temperature from 68* to 38* (F) it cut the amount of sugar needed in half.

Could someone explain this to me?
 
I got brewers friend on my android. When I changed the field for temperature from 68* to 38* (F) it cut the amount of sugar needed in half.

Could someone explain this to me?

That temperature setting is meant for the temp at which the beer fermented. The temp the beer was fermented at changes how much CO2 stays in solution. You won't gain any more CO2 after cold crashing since it already has as much in solution as it is going to get, assuming it was finished fermenting.
 
I should also point out that this is a highly debated topic. My $.02 is that unless you bring the beer temp up to an extremely high temp after fermentation completes, say bring it up from 62* to 72*, you're not going to lose much CO2. If you're going from 65* to 70* you're probably venting some, but that would be less than .25 volumes. I'm no expert on the matter and I think Revvy and others who disagree with him both have good points.

I can tell you for certain that you're not going to absorb more CO2 into solution after cold crashing because you would have started with a volume of x and that volume won't go up unless there is more CO2 being generated, so it will still be x after the temp drops.

https://www.homebrewtalk.com/f128/effects-cold-crashing-priming-sugar-needs-134347/
 
I got brewers friend on my android. When I changed the field for temperature from 68* to 38* (F) it cut the amount of sugar needed in half.

Could someone explain this to me?

The short answer, as already explained, is "it doesn't".

I hate those priming calculators! The temperature is almost always unimportant, as even with lagers they often have a diacetyl rest in the 60s, and are very confusing to people who try to use them. Also, they have you prime "to style". That's all well and good, if you're accustomed to that, but most people in the US who buy bottled commercial beer do not drink them "to style" and expect about 2.4-2.7 volumes of carbonation in all bottled beer.

The calculator would have you make your English brown carbed to something like 1.5 volumes (totally flat) and your wits to 4.5 volumes (bottle bombs).

Just like with every set of instructions, always ask yourself if something makes sense. If it doesn't it probably is wrong.
 
The short answer, as already explained, is "it doesn't".

I hate those priming calculators! The temperature is almost always unimportant, as even with lagers they often have a diacetyl rest in the 60s, and are very confusing to people who try to use them. Also, they have you prime "to style". That's all well and good, if you're accustomed to that, but most people in the US who buy bottled commercial beer do not drink them "to style" and expect about 2.4-2.7 volumes of carbonation in all bottled beer.

The calculator would have you make your English brown carbed to something like 1.5 volumes (totally flat) and your wits to 4.5 volumes (bottle bombs).

Just like with every set of instructions, always ask yourself if something makes sense. If it doesn't it probably is wrong.

So I should leave the temperature field at a room temperature?
 
You can either go by the highest temp the beer was at during active fermentation, or you can go by the highest temp the beer has been at since then. Unless you had some wild temp swings I don't think it will make much difference either way.

For my batches, unless it is an English style or a stout, I just prime with 4.5oz to a 5 gallon batch and call it day. Seriously I wouldn't put too much into it, as Yooper said, those calculators are a mess.
 
Thanks everyone so since I went by that calculator for my last batch, should I add a carb tab to the bottles?
 
Thanks everyone so since I went by that calculator for my last batch, should I add a carb tab to the bottles?

Probably not. When you add something like a carb tab, you'll create thousands of nucleation points and cause foaming (and then lose the carbonation and maybe some beer). If it's flat, and you absolutely can't drink it, then maybe, but only as an absolute last resort.
 
That temperature setting is meant for the temp at which the beer fermented. The temp the beer was fermented at changes how much CO2 stays in solution. You won't gain any more CO2 after cold crashing since it already has as much in solution as it is going to get, assuming it was finished fermenting.

Actually there will be a layer of CO2 above the cold-crashed wort/brew, [think about when you crack open a cold bottle of beer and a fog of gas slowly unfolds, and as the wort/brew warms up, even a little, the wort/brew will suck in and absorb this CO2, and any other gas for that matter that may be hanging around. So if you cold crash, and then bottle at room temperature, do it quickly to avoid possible oxidation.
 
Actually there will be a layer of CO2 above the cold-crashed wort/brew, [think about when you crack open a cold bottle of beer and a fog of gas slowly unfolds, and as the wort/brew warms up, even a little, the wort/brew will suck in and absorb this CO2, and any other gas for that matter that may be hanging around. So if you cold crash, and then bottle at room temperature, do it quickly to avoid possible oxidation.

I'm trying to figure the physics behind this, but I just can't.

How can bottling at cooler temperatures avoid oxidation but bottling at room temperatures cause it? That doesn't make sense to me from a physics/ideal gas law standpoint.
 
I was really hoping to keg my first batch. I left the carboy in the fridge for about 3 weeks now and I took the keg I had gotten for free a few months ago into my lhbs. One of the guys there hooked it up to co2 and put soapy water on it. Basically it can't be used because of where the leak is.


So I went to my Brewers Friend app I have for android. Punched in the numbers it asked me for, batch size, vol co2 desired and temperature at bottling in farenheit. I noticed it went from like 4 oz down to 2.2 oz of corn sugar when I changed the temp to 38*
Just didn't think that seemed right, so I asked you all.


So thanks, everyone for the input! Looks like ill be bottling for a little while longer than i hoped lol.
 
Yooper said:
I'm trying to figure the physics behind this, but I just can't.

How can bottling at cooler temperatures avoid oxidation but bottling at room temperatures cause it? That doesn't make sense to me from a physics/ideal gas law standpoint.

When the cool beer warms up, and it will as you prime it and prepare it for bottling or kegging (I don't keg) it will suck in and absorb the gases available to it. Chill a half full plastic bottle of water in an ice bath and be sure it's cap is screwed on tight. Then set that bottle out on its own to warm up and watch the bottle begin to collapse on itself as the water absorbs the gases available to it. Same thing with beer, whether its in the bottle or not. Even when cold crashing and prepping for bottling, kegging. Common sense physics tells you the warmer the liquid, the less co2 it can hold. But in the case of cool liquids - they have the capacity to hold more gases. If a cool liquid has the capacity to hold more gas and it hasn't absorbed its capacity then it will begin to absorb and dissolve/hold more gas when it has the opportunity to do so, even when it's coolness is becoming less cool. Try the plastic water bottle experiment and see if you get the same results.
 
Also could be perceived as a weather system with high and low pressures. Cool liquid warming up (with the capacity to absorb more gases) and cool gases warming up will naturally force more gases into cool liquid. Though I'm no physicist but this is just my take on what I've seen and so i strive to quickly bottle, having cold crashed or not, to keep exposure to O2 at a minimum. I need a CO2 room and to wear scuba gear when I bottle.
 
Also could be perceived as a weather system with high and low pressures. Cool liquid warming up (with the capacity to absorb more gases) and cool gases warming up will naturally force more gases into cool liquid. Though I'm no physicist but this is just my take on what I've seen and so i strive to quickly bottle, having cold crashed or not, to keep exposure to O2 at a minimum. I need a CO2 room and to wear scuba gear when I bottle.

Then why, when I open a beer there is lots of carbonation and if I leave it until it is warm it is totally flat??

This makes no sense to me either. And does not jibe with my experience.
 
Then why, when I open a beer there is lots of carbonation and if I leave it until it is warm it is totally flat??

This makes no sense to me either. And does not jibe with my experience.

I agree. What little CO2 that stays in the headspace of the carboy or bucket isn't going to be enough to make much difference, even if it is somehow reabsorbed.

Besides, your example of a sealed water bottle is contrary to my experience since any time I've ever cold crashed in a carboy I've never had the airlock suck back sanitizer, or had a vacuum affect when removing the stopper. EDIT - I have had the airlock suck back with pressure changes (thunderstorms/storm fronts). If it were somehow reabsorbing the CO2 in the headspace, that volume of CO2 would have to be replaced with another gas/liquid.
 
When the cool beer warms up, and it will as you prime it and prepare it for bottling or kegging (I don't keg) it will suck in and absorb the gases available to it.

Common sense physics tells you the warmer the liquid, the less co2 it can hold. But in the case of cool liquids - they have the capacity to hold more gases.

You seem to be saying contradictory things here. The solubility of most gases goes down as the temperature increases, so I'm not really sure what you're trying to say in that first statement. A liquid that is saturated with a dissolved gas (and beer is typically saturated with CO2 at the end of fermentation) will release gas into the air as it warms up since the solubility of said gas is going down.
 
I think the confusion is whether the liquid is saturated with gas at the lower pressure. CO2 production is from the yeast consuming the sugar during EITHER primary fermentation, or during bottle conditioning (with priming sugars).

So, if the temperature stays at or below the primary fermentation temperature, the volume of CO2 in the beer should theoretically remain the same as the saturation volume at that temperature. IF a lager temp is raised AFTER primary fermentation, some of that CO2 will leave solution to equalize at the new saturation pressure. When cooled again, since the gas space pressure has equalized through the airlock, there is no "driving force", if you will, to push CO2 back into solution.

However, during bottle conditioning, the gas space is NOT equalized with atmosphere and so retains a "driving force" to move CO2 into solution when chilling the beer.
 
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