Correct Priming Sugar calc

[brandonlovesbeer]

I read recently (but cannot find definitive documentation) that when I'm trying to calculate the correct amount of priming sugar, I need to take in to consideration the temperature of the beer.

But...

Not the temperature that it is currently at, but the temperature at which the primary fermentation took place.

Can anyone confirm this?

Thanks

 

[Anon111]

It makes sense, if you're strikter than 'if it foams, it 'll do'.
Run a 5-gallon batch, split 'm up in 5, add:

• suggested sugar -20%
• suggested sugar -10%
• suggested sugar
• suggested sugar +10%
• suggested sugar +20%

and let us know what happened

This calculator says:

"* Temperature of Beer used for computing dissolved CO2:
The beer you are about to package already contains some CO2 since it is a naturally occurring byproduct of fermentation. The amount is temperature dependent. The temperature to enter is usually the fermentation temperature of the beer, but might also be the current temperature of the beer. If the fermentation temperature and the current beer temperature are the same life is simple.

However, if the beer was cold crashed, or put through a diacetyl rest, or the temperature changed for some other reason... you will need to use your judgment to decide which temperature is most representative. During cold crashing, some of the CO2 in the head space will go back into the beer. If you cold crashed for a very long time this may represent a significant increase in dissolved CO2. There is a lot of online debate about this and the internet is thin on concrete answers backed by research. We are open to improving the calculator so please let us know of any sources that clarify this point. "

 

[brandonlovesbeer]

Unfortunately my beer fermented around 78°F. Pretty high, I know. But then I cold crashed (down to 28°F) and fined with Geletin. Once I added the Geletin I let it sit at 37°F for about 4 days.

 

[doug293cz]

Unless you backfill the headspace with CO2 while cold crashing, the answer is to use the highest temp the beer saw after fermentation was complete (i.e. CO2 generation stopped.) For a detailed explanation (with lots of math and science) read this.

Brew on

 

[AZCoolerBrewer]

Unless you backfill the headspace with CO2 while cold crashing, the answer is to use the highest temp the beer saw after fermentation was complete (i.e. CO2 generation stopped.) For a detailed explanation (with lots of math and science) read this.

Brew on

This guy has it right. Think of a beer you are drinking. The reason the bubbles continue to flow in your beer is that it is slowly getting warmer. At some point your beer would reach room temperature and the amount of CO2 in your beer stays dissovled there that can at that temp. Lowering the temp of the beer at that point would not return any CO2 into your beer. You would have to add it by fermenting more sugar in a closed container (bottling) or by forcing it in under pressure (kegging). So assuming you cold crashed your beer after fermentation, then your fermentation temp would be used in the calculation until such time that the beer reaches a higher temp before the beer is enclosed in the bottles.

 

[brandonlovesbeer]

Okay. So I have 5 gals to bottle. The carboy was sitting steady at 37°F since my original post. The final Gravity is probably around 1.010-ish.
When I bottle the temp will probably rise to around 45°.

 

[doug293cz]

Okay. So I have 5 gals to bottle. The carboy was sitting steady at 37°F since my original post. The final Gravity is probably around 1.010-ish.
When I bottle the temp will probably rise to around 45°.

Is there an implied question in there somewhere?

Brew on

 

[MindenMan]

I have been brewing for 5 plus years, and the only thing the brew calculators ever did was confuse me. If I am making a porter or similar I use 3/4oz of table sugar per gallon, and if I am making a lighter flavored beer I will use 1oz of table sugar per gallon. My beers do not carb quickly and I am fine with that. For priming 5 gallons of hard cider I use one 12oz can of FAJC, and am always happy with the results.

 

[Yooper]

Okay. So I have 5 gals to bottle. The carboy was sitting steady at 37°F since my original post. The final Gravity is probably around 1.010-ish.
When I bottle the temp will probably rise to around 45°.

It doesn't matter. If it was at 78 degrees before you cold crashed, no matter how cold it got later won't affect the dissolved c02.

I don't use a priming calculator, ever. For more highly carbed styles (like a light lager), I use 1 ounce of dextrose per gallon of finished beer. For "regular", I use .75 ounce of dextrose per gallon of finished beer. It works great.

If you want to use a priming calculator, use the highest temperature the beer reached during or after fermentation. It's still just a guestimate on how much c02 is dissolved in the beer (due to things like airlock pressure) but it's a decent guess if you use the calculator correctly.

 

[brandonlovesbeer]

It doesn't matter. If it was at 78 degrees before you cold crashed, no matter how cold it got later won't affect the dissolved c02.



If you want to use a priming calculator, use the highest temperature the beer reached during or after fermentation. It's still just a guestimate on how much c02 is dissolved in the beer (due to things like airlock pressure) but it's a decent guess if you use the calculator correctly.

Okay. That's essentially what I heard. Which prompted me to ask the original question. I just needed someone to confirm this.

Thanks

 

[doug293cz]

Okay. That's essentially what I heard. Which prompted me to ask the original question. I just needed someone to confirm this.

Thanks

I thought I did in post #4 to this thread.

Brew on