I'm about to transfer my wheat beer into a keg and was wondering if I can carb it with corn sugar. My plan was to let it sit for two weeks and then put in the kegerator. If possible, how would I go about doing this? My other option is putting it in the kegerator and let it carb at 12psi. Thanks!
Carbing a keg with corn sugar
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kev211
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Yes you can do that. You would do it the same way as you would with bottling. Calculate how much corn sugar you need, boil it, cool it, yadda yadda, add it to the beer or keg and rack your beer to the keg and set aside for 2 weeks. Some people do it this way, but I prefer to hit it with 12-16 psi for a couple days. To me its one of the big benefits of kegging
You can use corn or cane sugar. I've done it this way many times. Boil about 5 ounces of sugar in about 8 ounces of water for 10 minutes or so. Dump it into the keg (no need to let it cool, since it's such a small amount going into 5 gallons of beer), rack the beer into the keg, hit it with some CO2 to seal the keg, and let it sit at room temp for a week or so.
This - but I'd add the priming sugar/malt you use needs to be about 75% of what you use to bottle, i.e., about .75 oz/gal. Also seal the keg with CO2 after filling. This will keep the CO2 generated from leaking out.
You can leave your keg at room temp, usually 7-10 days. Then cold crash for about 48 hours before tapping.
kev211
Well-Known Member
Ive never heard that. Interesting. Wonder why that is? Thats one of the reason I like carbing with co2. I have more precise control over the carbonation and dont have to worry about over or under carbing
I've used this on 50% or so of my brews. I've never had an over carb. Also, the carb is smoother for lack of a better term.
kev211
Well-Known Member
Apparently not. Use 50-75% of normal priming sugar as suggested by govner.But to seal with co2, just hook your tank up to the keg and charge with co2 until the lid seals
works great. Call me lazy, but I don't even boil my water. I just use hot water from the tap and have never had an infection. In addition, any oxygen in the water will get used up by the yeast in the process of carbing the beer. The only downside to naturally carbing in the keg is that you will get a layer of sediment in the bottom of the keg from the yeast settling out once it is done with the sugar. However, that usually comes out with the first pint or two and the beer runs clear after that.
The way I avoid issues w/ the yeast sediment is by shortening my dip tube about 3/4-1" and adding a SS trap to the end. Works great!
I mark my legs w/ shortened dip tubes w/ a zip tie on the handle.
The recommendations to use less sugar when naturally carbonating a keg then when bottling are nonsense. A keg is just a big bottle. The ratio of headspace to beer in a full keg and a properly filled bottle is virtually the same (about 6%.) Using less sugar in a keg will just give you less carbonation than you intended. However, after long enough on CO2 for serving, the carb level eventually reach the target level.
Brew on
Brew on
Gnomebrewer
Well-Known Member
The recommendations to use less sugar when naturally carbonating a keg then when bottling are nonsense. A keg is just a big bottle. The ratio of headspace to beer in a full keg and a properly filled bottle is virtually the same (about 6%.) Using less sugar in a keg will just give you less carbonation than you intended. However, after long enough on CO2 for serving, the carb level eventually reach the target level.
Brew on
No, it's not nonsense. Have you tried carbonating in a keg with the same amount as you'd use for bottles? I have, and it didn't work (way over-carbonated). I now use a bit more than half the bottle amount. Maybe it's because the headspace in the keg is already pressurised (i.e. effectively zero headspace)?
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There is no science behind my process. I prime the keg at 50% what is recommended for bottling. I shoot the keg with one 12 gram co2 cartridge to seal the lid. I was given a little hand held thingy do that holds that one cartridge .. so no equipment cost. It can sit at room temp until a cooled keg kicks. When it first goes in, it is very slightly over carbed. The first pint spews the sediment - the second pint is foamy - but by the 3rd or 4th everything has settled to 12psi and life is too good for words.
I keg carbonate most of my clean beers intended for aging and then also any beers I need to keg when I don't have room in my keezer. I microwave table sugar in water to get it at least near a boil.
I calculate sugar and go with either 50%-100% of recommended based on what I am trying to accomplish. Any are enough to remove oxygen and generate a layer of yeast to get the benefit of "bottle conditioning" while in the keg and will sufficiently carbonate to keep the keg sealed.
I will do 100% for a beer I want carbed above my normal serving pressure for competition or gifting purposes. Like a belgian Tripel or a Gose that I like at 3+ volumes. These will be chilled and then hooked up to gas just for purpose of filling with a beer gun. Any that don't get filled end up equilibrating down to my standard serving pressure.
I will go on low side for most American APAs and IPAs because I enjoy these in a range of carbonation levels all the way down to about 1.5 volumes up to 2.5 or so. These kegs start out at low end of my range and finish up at high end after a week or so on serving pressure.
The only time I've overcarbed keg conditioning it was due to a beer that wasn't actually done fermenting. Was in a hurry for fermentation space, thought it looked done, and transfered. At least that wasn't into bottles...
I calculate sugar and go with either 50%-100% of recommended based on what I am trying to accomplish. Any are enough to remove oxygen and generate a layer of yeast to get the benefit of "bottle conditioning" while in the keg and will sufficiently carbonate to keep the keg sealed.
I will do 100% for a beer I want carbed above my normal serving pressure for competition or gifting purposes. Like a belgian Tripel or a Gose that I like at 3+ volumes. These will be chilled and then hooked up to gas just for purpose of filling with a beer gun. Any that don't get filled end up equilibrating down to my standard serving pressure.
I will go on low side for most American APAs and IPAs because I enjoy these in a range of carbonation levels all the way down to about 1.5 volumes up to 2.5 or so. These kegs start out at low end of my range and finish up at high end after a week or so on serving pressure.
The only time I've overcarbed keg conditioning it was due to a beer that wasn't actually done fermenting. Was in a hurry for fermentation space, thought it looked done, and transfered. At least that wasn't into bottles...
The recommendations to use less sugar when naturally carbonating a keg then when bottling are nonsense. A keg is just a big bottle. The ratio of headspace to beer in a full keg and a properly filled bottle is virtually the same (about 6%.) Using less sugar in a keg will just give you less carbonation than you intended. However, after long enough on CO2 for serving, the carb level eventually reach the target level.
Brew on
Ignorance is bliss!
No, it's not nonsense. Have you tried carbonating in a keg with the same amount as you'd use for bottles? I have, and it didn't work (way over-carbonated). I now use a bit more than half the bottle amount. Maybe it's because the headspace in the keg is already pressurised (i.e. effectively zero headspace)?The recommendations to use less sugar when naturally carbonating a keg then when bottling are nonsense. A keg is just a big bottle. The ratio of headspace to beer in a full keg and a properly filled bottle is virtually the same (about 6%.) Using less sugar in a keg will just give you less carbonation than you intended. However, after long enough on CO2 for serving, the carb level eventually reach the target level.
Brew on
Ignorance is bliss!The recommendations to use less sugar when naturally carbonating a keg then when bottling are nonsense. A keg is just a big bottle. The ratio of headspace to beer in a full keg and a properly filled bottle is virtually the same (about 6%.) Using less sugar in a keg will just give you less carbonation than you intended. However, after long enough on CO2 for serving, the carb level eventually reach the target level.
Brew on
A fixed amount of sugar will create a fixed amount of CO2 when completely fermented. 1 oz of table sugar (sucrose) will create 0.5143 oz of CO2. 1 oz of corn sugar (dextrose mono hydrate) will create 0.4441 oz of CO2. Doesn't mater whether the beer containing the sugar is in a keg or bottle.
At the completion of fermentation, beer at 65˚ - 68˚F will contain about 0.8 volumes of CO2. Cold crashing after fermentation will not significantly increase the CO2 concentration in the beer. To carbonate to 2.5 volumes, you need to add enough sugar to create (2.5 - 0.8) = 1.7 volumes of additional CO2. 1 volume of CO2 is equal to 1.9768 g/L or 0.26396 oz/gal. To create 1.7 volumes of carb, you need to create:
1.7 * 0.26396 oz/gal = 0.44873 oz/gal of CO2
To create 0.44873 oz-CO2/gal, you need to add:0.44873 oz-CO2/gal / 0.5143 oz-CO2/oz-sucrose = 0.8725 oz-sucrose/gal
Now some of the generated CO2 will escape into the headspace in the package during carbonation. Since the headspace volume in a bottle with 12 oz of beer or a keg with 5 gal of beer in it is about 6% of the beer volume in either case (I measured both cases), the percent of the CO2 escaping from the beer into the headspace will be the same in either case, and the volumes of CO2 in the beer will be the same. The preceding is true as long as the keg headspace was not purged and pressurized with CO2.So, what happens if you purge the headspace and pressurize to 30 psi (gauge pressure)? In that case the headspace will contain about:
((30 psi + 14.7 psi) / 14.7 psi) * (273.15˚K / 277.59˚K) = 3.0 volumes of CO2
The first term above corrects for gauge pressure vs. absolute pressure, and the second term corrects for the temps of the CO2 (assumed to be 40˚F.) So, the headspace would contain about 3 volumes of CO2 immediately after pressurizing. Most of this CO2 will dissolve into the beer, and the volumes of CO2 contributed to the beer is calculated approximately as:0.06 * 3 volumes / 1.06 = 0.17 volumes
Thus in the case of pre-pressurized headspace, the beer would have about 0.17 volumes more carb than desired, and you would have 2.67 volumes instead of the intended 2.5. I don't think many people would consider this "way over-carbonated." So, instead of adding enough sugar to create 1.7 volumes, we only want to add enough to create:1.7 volumes - 0.17 volumes = 1.53 volumes
Then we want to use:1.53 / 1.7 = 0.90 => 90% of the sugar we would use in bottling.
This is a far cry from using only 50% (or even 75%) when kegging.So, if you pre-pressurize to 30 psi when naturally carbonating a keg, you should use about 90% of the priming sugar that you would use for bottling.
Show me where I'm wrong.
Brew on
Reading through this might help you-
http://www.beersmith.com/forum/index.php?topic=11810.0
http://www.beersmith.com/forum/index.php?topic=11810.0
No, but thanks for playing. That discussion doesn't provide any useful information.
The first answer in the linked forum says that bottles have more headspace per oz of beer than kegs. In my measurements the opposite was true. With 5 gal of liquid in my ball lock keg, I have 0.0625 fl oz of headspace per fl oz of beer. In a 12 oz bottle, I have 0.0595 fl oz of headspace per fl oz of beer. Need more CO2 to put the headspace in equilibrium in a keg than in a bottle. If the keg has less than 5 gal of liquid, then there is even more headspace per oz of beer, requiring even more CO2. In my analysis above I just assumed that both kegs and bottles had 0.06 fl oz of headspace per fl oz of beer.
Further down a poster speculates that the beer handling during bottling knocks out significantly more of the residual CO2 than does the handling during kegging, but provides absolutely no evidence to support this speculation. As stated in my previous post, beer that has reached the upper 60's post fermentation will contain about 0.8 volumes of CO2, and to get 2.5 volumes in the final beer requires 1.7 volumes of additional CO2. Even if we assume that bottling knocks half of the residual CO2 out of the beer, we still only need to add 2.1 volumes of CO2 to reach 2.5 volumes. So the ratio of priming sugar required for kegging vs. bottling would be 1.7 / 2.1 = 0.81 or 81%. Not even close to the common 50% recommendation. So this "handling" difference speculation doesn't explain the recommendation. The Brewer's Friend priming calculator recommends 4.4 oz of sucrose to prime 5 gal of beer at 68˚F, or 0.88 oz/gal. This is basically the same as the 0.8725 oz/gal I calculated in my previous post. So, the BF calculator is making no accommodation for the possibility of losing residual CO2 due to handling.
My analysis in my previous post is the most detailed I am aware of dealing with differences in priming kegs vs. bottles. If anyone knows of anything similar or (even better) more detailed, please let us all know. Links to other discussions containing no quantitative information are of no interest.
Brew on
Why use water at all? Why not decide on the amount of sugar and just dump it in the keg? I understand the reason for suspending the sugar in water when bottling, since otherwise you'll need to do a separate and annoying measurement for each bottle, but that reasoning does not hold true for kegs, does it? If Coopers DIY drops work in tablet form, granulated dextrose should work even better.
chickypad
lupulin shift victim
I totally trust doug on the calculations, but in practice I will say that I had the experience of overshooting a bit when using the full priming amount. I tend to use about 3 oz now. I do fill my kegs really full, like up to the gas diptube full, and I seal with the high burst of pressure. I very well may be undershooting - as someone pointed out small differences in carb levels are hard to tell - but since the beer goes on the gas anyway I'd rather undershoot a little then overshoot. At the 3 oz it's good to drink right away so I stick to that.
nettekdl
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I totally trust the math, but anecdotally I can say it doesn't hold up. I have naturally conditioned probably 50 kegs atleast when my keezer is full and the first atleast 10ish I used the reccomended full dose via the NB calculator and was way overcarbed. After reading I cut back to about 60% and every single keg I have done that with have been perfect. I am no mathematician or scientist but I can say from experience that is how it is for me.
Nice to think you're always right when you're unwilling accept input from those with a great deal of experience.
Oh well! No point in having a having a verbal duel with an unarmed man.
Oh well! No point in having a having a verbal duel with an unarmed man.
Do you have anything to offer other than insults?
I have carefully laid out my reasoning and calculations, but have yet to see anyone provide a science based explanation for what they seem to be observing w.r.t higher than calculated levels of carbonation. If the priming sugar added is not enough to create the amount of CO2 generated in the keg, then where is the extra CO2 coming from? If it is in fact a real phenomenon, then there has to be an explanation for it. Show me the explanation, and I will thank you for it, and admit that my analysis failed to account for whatever it was.
Brew on
Gnomebrewer
Well-Known Member
I have carefully laid out my reasoning and calculations, but have yet to see anyone provide a science based explanation for what they seem to be observing w.r.t higher than calculated levels of carbonation. If the priming sugar added is not enough to create the amount of CO2 generated in the keg, then where is the extra CO2 coming from? If it is in fact a real phenomenon, then there has to be an explanation for it. Show me the explanation, and I will thank you for it, and admit that my analysis failed to account for whatever it was.
Brew on
Maybe I'm missing something, but I think that you yourself (Doug) have given the science based explanation for using less priming sugar than the bottle priming calculators. Please correct me if I'm wrong (and there's a good chance I am) but using your number (in metric), to carbonate a keg (with the headspace already pressurised) to 2.5vols I'd need:
1.53volumes x 1.9768 g/L/volume x 19L = 57g.
This is spot on what I use in a keg (50g for lower carbonation, 60g for higher carbonation).
Putting the same info into a calculator (brewersfriend) for 19L of beer being bottled, fermented at 20C, 2.5volumes of carbonation it says to use 124.5g of priming sugar. That's approximately double to keg amount.
You are correct that you need to create 57.5 g of CO2 to add 1.53 volumes of CO2 to 19L of beer. But you only get 0.5143 g of CO2 for each gram of sucrose you add (0.4441 g CO2 / g corn sugar.) So, you need to divide the g of CO2 needed by either 0.5143 or 0.4441 (depending on type of sugar) to determine how much sugar to add. That would be either:
57.5 / 0.5143 = 112 g of sucrose, or
57.5 / 0.4441 = 129 g of corn sugar
Your Brewer's Friend number is for sucrose, but doesn't factor in the pre-pressurized headspace.57.5 / 0.4441 = 129 g of corn sugar
Brew on
Gnomebrewer
Well-Known Member
You are correct that you need to create 57.5 g of CO2 to add 1.53 volumes of CO2 to 19L of beer. But you only get 0.5143 g of CO2 for each gram of sucrose you add (0.4441 g CO2 / g corn sugar.) So, you need to divide the g of CO2 needed by either 0.5143 or 0.4441 (depending on type of sugar) to determine how much sugar to add. That would be either:57.5 / 0.5143 = 112 g of sucrose, orYour Brewer's Friend number is for sucrose, but doesn't factor in the pre-pressurized headspace.
57.5 / 0.4441 = 129 g of corn sugar
Brew on
Ah, ok. So the 1.9768 figure is for grams of CO2, not grams of sugar. Makes sense. I'd still like to know why keg priming uses less sugar. Like you say, according to the maths, it shouldn't.
I have carefully laid out my reasoning and calculations, but have yet to see anyone provide a science based explanation for what they seem to be observing w.r.t higher than calculated levels of carbonation. If the priming sugar added is not enough to create the amount of CO2 generated in the keg, then where is the extra CO2 coming from? If it is in fact a real phenomenon, then there has to be an explanation for it. Show me the explanation, and I will thank you for it, and admit that my analysis failed to account for whatever it was.
Brew on
I thought some more about the highlighted question, and the only possible source for the extra CO2 is additional fermentation of the original wort sugar. Creating 1.7 volumes of CO2 requires the fermentation of about 2.5 gravity points. If the extra CO2 is half of the required new CO2, then it only requires fermenting the beer an additional 1.25 gravity points.
A couple of possibilities come to mind for why kegging could lead to additional fermentation of the "fully fermented" beer:
- Since the kegs are stainless steel, maybe that catalyzes some additional fermentation that wouldn't happen in a glass/plastic bottle. Since most brewers ferment in glass or plastic, this catalysis wouldn't occur until after kegging. This phenomenon wouldn't occur if the original fermentation was done in stainless.
- Since keggers don't have to worry about bottle bombs, they may be less rigorous about insuring fermentation is actually complete prior to kegging. This might happen often enough that kegs get a rep for overcarbing with normal levels of priming sugar.. Thus recommendations to use less priming sugar when kegging came into vogue.
Brew on
I would imagine you use less priming sugar because you desire less carbonation to avoid over foaming with pouring when using a keg.
In a bottle it's easy to carb to 2.5 volumes of CO2 and pour without too much foam. In a keg, unless you have a lot of resistance (long lines) - pouring that 2.5 volumes of CO2 might cause too much foaming.
So maybe in a keg the recommendation is to carbonate to 2 volumes of CO2 to avoid that issue?
^not science. Based on my newbie brewing logic.
In a bottle it's easy to carb to 2.5 volumes of CO2 and pour without too much foam. In a keg, unless you have a lot of resistance (long lines) - pouring that 2.5 volumes of CO2 might cause too much foaming.
So maybe in a keg the recommendation is to carbonate to 2 volumes of CO2 to avoid that issue?
^not science. Based on my newbie brewing logic.
I had a similar thought, i.e. that some people unconsciously prefer lower carbonation in their draft beer, so think it is overcarbed when carbed to "normal" levels. The problem with this idea is that about a week or two after hooking a keg up for serving, the carb level will be back to the "normal" level as that is the equilibrium level for the serving pressure chosen. If people set their pressures for less carb, then it would be a conscious decision to have a lower level of carbonation.
Brew on
chickypad
lupulin shift victim
I had a similar thought, i.e. that some people unconsciously prefer lower carbonation in their draft beer, so think it is overcarbed when carbed to "normal" levels. The problem with this idea is that about a week or two after hooking a keg up for serving, the carb level will be back to the "normal" level as that is the equilibrium level for the serving pressure chosen. If people set their pressures for less carb, then it would be a conscious decision to have a lower level of carbonation.
Brew on
Right. I have my system set to 2.6 vols, and compared to bottled beers my kegged beers are definitely well carbonated c/w what I would expect at 2.6. Is it possible that maybe we're not chilling enough and getting the CO2 into solution before tapping, so on initial tap it seems overcarbed? Trying to remember now on the few kegs that seemed overcarbed how long they chilled. I typically do something like set the keg in the keezer for 24-48 hrs after natural carbing then hook them up to gas.
At any rate, since the 3 oz gets me close enough that I can't tell the difference and don't have trouble pouring at 24 hrs I'll probably just continue that way.
Gnomebrewer
Well-Known Member
I'm wondering if it could be the loss of CO2 from bottles that causes the discrepancy.
Assuming the carbonation is the same in a bottle as it is in the keg with the same rate of sugar (adjusting for the pressurised head space in the keg), when you open a bottle you lose the CO2 from the headspace, allowing CO2 bubbles to immediately start leaving the beer. You then (mostly) pour into a glass, which removes more CO2. On draught, the lines are balanced so you should lose minimal CO2, thus it might be more 'efficient' at keeping the carbonation.
This would mean that 2.5volumess in a bottle might only be, say, 2.0vols equivalent from a keg. Remembering that there are about 0.8vols in solution from fermentation, that means adding 1.2vols vs adding 1.7vols. Removing the volume for the pressurised headspace, you'd only need to add 1.0 to 1.1volumes in the keg, or about 2/3 of the equivalent bottle amount. It's even more exaggerated for me because I like lower carbonation - I go to about 2.0volumes in the bottle. Using the same (dodgy guesswork) maths as above, that means using about 50% of the sugar in the keg.
To test this, I might carbonate a keg using the full dose of sugar (I also bottle some off each batch - 7gal batches), test the carbonation off the keg vs. the bottle (I'm sure the keg will be too high) then take the lid off the keg and try pouring some into a jug, using it like a big bottle. Of course, once I've opened a keg like this it needs to be gone in a night.
Assuming the carbonation is the same in a bottle as it is in the keg with the same rate of sugar (adjusting for the pressurised head space in the keg), when you open a bottle you lose the CO2 from the headspace, allowing CO2 bubbles to immediately start leaving the beer. You then (mostly) pour into a glass, which removes more CO2. On draught, the lines are balanced so you should lose minimal CO2, thus it might be more 'efficient' at keeping the carbonation.
This would mean that 2.5volumess in a bottle might only be, say, 2.0vols equivalent from a keg. Remembering that there are about 0.8vols in solution from fermentation, that means adding 1.2vols vs adding 1.7vols. Removing the volume for the pressurised headspace, you'd only need to add 1.0 to 1.1volumes in the keg, or about 2/3 of the equivalent bottle amount. It's even more exaggerated for me because I like lower carbonation - I go to about 2.0volumes in the bottle. Using the same (dodgy guesswork) maths as above, that means using about 50% of the sugar in the keg.
To test this, I might carbonate a keg using the full dose of sugar (I also bottle some off each batch - 7gal batches), test the carbonation off the keg vs. the bottle (I'm sure the keg will be too high) then take the lid off the keg and try pouring some into a jug, using it like a big bottle. Of course, once I've opened a keg like this it needs to be gone in a night.
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I'd have a neighbor that I don't like 'take the lid off the keg' if you are not venting the co2 first.
Gnomebrewer
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Yes, the CO2 will be vented first.
I’m hip to what gnome brewer says. There is a noticeable difference in carbonation when drinking from the bottle vs pouring it into a glass. If beer on tap delivers that carbonation it could help to account for the discrepancy between the math and practice.
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I recently started kegging. I have 3 gallon kegs and brew 2.5 to 2.75 gallons of beer. My 3rd keg is a Munich style lager and I chose to prime it with 1 oz of dextrose. I sealed the keg with 10-12 psi of CO2 and I've tasted it twice. It has carb, needs a little more, clear and no sediment on the first 2 6 oz pours. Will place in fridge this weekend and then hook up to CO2 at serving pressure. I'm hoping the extra carb and cold will give it a little more mouthfeel than I get at room temp, 70 deg that is.
