Priming with sugar vs wort

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Priming with sugar vs wort

Postby caughtinamosh87 » Tue Feb 07, 2012 10:25 am

I've always used corn sugar for carbonation when bottling. Thinking about using unfermented (obviously) wort for it instead. How much should I use? What is best for storing it, fridge or freezer?
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Carbonating with wort

Postby slothrob » Tue Feb 07, 2012 9:31 pm

32 oz of 1.040 wort will add about 2.5 volumes to 5 gallons of beer.

You can use those proportions to adjust for the gravity of your priming wort, your desired volumes of CO2, or the amount of beer you want to prime.

You should probably freeze the wort. Wort isn't sterile, even after it has been boiled and especially after you transfer it to a secondary container, so you run some risk of having it start to go sour in the fridge over 2-3 weeks. I'd probably re-boil it right before I primed with it, too, just to be safe.
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Postby caughtinamosh87 » Thu Feb 09, 2012 4:59 pm

Thank you! I was guessing 16oz. Guess it will be another of those trial and error for awhile.
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Postby caughtinamosh87 » Sun Feb 12, 2012 3:40 pm

Shooting for 1.052 for the first trial. Any guestimate for the amount for that?
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Carbonating with wort

Postby slothrob » Sun Feb 12, 2012 9:54 pm

In my answer before, I forgot to take into account the fermentability of the wort and the difference between real and apparent attenuation.

Assuming that the beer will go from about 1.052 to 1.012, the real attenuation is to 1.019 (see the analysis tab in BTP). 52 -19= 33 points

32 oz x 40 points ÷ 33 points = 39 oz.

Another way to calculate that would be if 2 points per gallon adds ~2.5 volumes of CO2, then 2 points/gallon x 5 gallon = 10 points,
10 points ÷ 33 points/gallon = 0.303 gallons,
0.303 gallons x 128 oz/gallon = 39 oz.

There is some guess work here, initially, since we don't actually know the FG. By the time you bottle, you'll know the FG of the beer and be able to calculate it more precisely. The amount will also vary depending on the fermentation temperature, but I assumed your beer would be in the mid 60s.

Here is an Excel spreadsheet from Kai Troester that is designed to calculate this, too, and it seems to come up with a similar answer.
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Postby caughtinamosh87 » Mon Feb 13, 2012 4:54 pm

Thank you again! So if I'm reading this right, the higher the gravity, the more you'll need to carbonate. I would've guessed the other way around.

How does temperature figure into it? I'm in AZ, so getting to ferment in the mid 60s, even in the "cooler" months isn't always possible. At least not with my set up.

Thanks for the link to the spreadsheet. Now only if I understood it. :?
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Priming with wort

Postby slothrob » Mon Feb 13, 2012 8:30 pm

Maybe my explanation was a little confusing. The higher the OG of the priming wort, the less you'll need. The higher the expected FG of the priming wort, the more you'll need.

Cold wort holds more of the CO2 produced during fermentation than warm wort. If you look at the effect of temperature on the BTP carbonation calculator and vary the temperature of the wort, you can see how this works. It's not a huge effect, but a 15°F difference in the wort temperature can make about a 10% difference in the final level of carbonation.
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Postby caughtinamosh87 » Fri Mar 23, 2012 10:59 am

Well after a few weeks in bottles, it came out nicely. That spreadsheet helped a bunch since we didn't originally keep enough, had to use a little corn sugar. Will definately continue to do this. Thanks again for your assistance!
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Wort priming

Postby slothrob » Sat Mar 24, 2012 8:24 am

Glad it worked out.

Did you prime any bottles with sugar alone to see if it made a difference in the final beer?
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