Why does carbing take so long? Explain...

[tj218]

Bottle conditioning: I know the standard advice is to wait 3 weeks for carbing at 70F. But why? Looking for more of a scientific answer.

If the yeast can chew threw a 1.050 OG in a couple days, why does a very small (by volume) amount of corn sugar take 3 weeks? I mean I could see maybe a week to allow clean-up of off flavors but still...is there a reason?

 

[RhesusPuffs]

There's also the time it takes for the CO2 to be forced into solution. Some beers are carbonated sooner, but three weeks is a safe estimate.

 

[DrummerBoySeth]

It only takes a week or 2 for the yeast to eat the priming sugar. The rest of the time allows the gas to be absorbed into the beer. Sort of like force-carbing a keg. You pressurize the keg and put it in the fridge, but you still have to wait a week or 2 for that gas to become carbonation. During the first part of bottle conditioning, the yeast eat the priming sugar and make CO2. Then, during the second part, that gas absorbs into the beer and becomes carbonation. In general, the whole process takes 3 weeks for most average beers. Some beers will be done in as little as a week, and some higher alcohol beers may take months to carbonate properly.

I guess what I am saying is: it takes so long because it is a 2 step process and you need time for both steps to be completed.

 

[tj218]

Wouldn't just cold crashing it for a few days force the CO2 into solution?

 

[Johnnyhitch1]

Wouldn't just cold crashing it for a few days force the CO2 into solution?

Its not only about carbing but how the beer mellows and ages into its "prime"

If you were able to tell when all sugars were fermented and "cold crashed" in the fridge im sure you could cut off maybe 5 days of your 3 weeks but for me its really when the beer is in its prime that i will open it. Makes it that much better!

Your also looking at A LOT less yeast to chew thru said sugars, just like an under-pitched batch takes longer to ferment...

 

[Maxkling]

If you go through a timeline, usually within a few days you'll get a gas relief when you pop the top(about the same as a regular beer or even more aggressive), but your beer will still be flat. It takes time to absorb that pressure into the solution to carbonate the beer.

Also a good bit of yeast drops out of the solution and you rack on top of it. Thus there is a lot less yeast to eat the sugar, resulting in a longer time to ferment out your prime.

Just like everything with home brewing, there is a lot of inconsistency. Ive had a beer ready in about 10 days, or take a month. I usually try a beer every 7 days until I call it good to go.

 

[TopherM]

If the yeast can chew threw a 1.050 OG in a couple days, why does a very small (by volume) amount of corn sugar take 3 weeks?

Also, remember that the yeast slow down in an alcohol environment. In any wort fermentation, the yeast go through the most active part of fermentation rather quickly, like you state, waxing off like 75-80% of the fermentables, but they always slow down once they start swimming around in their own alcohol byproduct. If you were to chart the gravity of a fermentation, the first 75-80% takes about 24-36 hours, but the last 20% or so always takes 3-5 days or so. That last 20% or so is so slow and subtle that it doesn't even typically tik the airlock.

Same thing in carbing. The yeast are working slowly in an alcohol environment. Everyone is right that a good bit of the 2-3 week guideline is letting the carbonation absorb into the beer, but also your yeast are just working much more slowly compared to the most active part of a new fermentation.

 

[zeg]

I think, in addition to the much lower yeast counts and the higher alcohol concentration, it's also to do with the lower concentration of fermentables. During primary fermentation, you have a huge concentration of sugar. A yeast cell can't float very far before it encounters a bit of sugar to ferment. As the sugar is consumed, it takes longer and longer for a yeast cell to "find" more sugar. This is why fermentation is not a linear process: as the amount of sugar drops, so does the rate at which it is fermented, giving you a (roughly) exponential gravity vs time curve. You are not adding much sugar per volume when you prime, so you're not going to ferment 3-4 ounces as fast as you would ferment the first 3-4 ounces of the sugars in your wort, even if the alcohol were not present and you roused all the yeast back up.

 

[Homercidal]

There are a LOT fewer yeast cells in a primed bottle than in a fermenter full of fresh wort.

There are a LOT fewer fermentable particles for the yeast to eat.

It takes longer for those fewer number of yeast to find those fewer number of fermentables and eat them.

 

[NordeastBrewer77]

Bottle conditioning: I know the standard advice is to wait 3 weeks for carbing at 70F. But why? Looking for more of a scientific answer.

If the yeast can chew threw a 1.050 OG in a couple days, why does a very small (by volume) amount of corn sugar take 3 weeks? I mean I could see maybe a week to allow clean-up of off flavors but still...is there a reason?

Yeast act very differently in a sugar rich, alcohol free environment that's not under pressure than they do in a alcohol rich, low sugar, pressurized environment. Then there's the fact that in the fermenter, a few hundred billion cells are at work, in the bottle, maybe a few dozen million.
Not very scientific, I know, but that's the basics of it.

 

[Noontime]

In addition to all the wonderful answers so far...it also allows some time for the yeast to settle to the bottom of the bottle. I don't mind drinking yeast but it's certainly a downside of bottle conditioning, so allowing the yeast to fall and pouring off the top of it is beneficial.

 

[itsernst]

The other thing is the priming solution that you are using. I currently use corn sugar, but I don't fee like it gives me enough carbonation no matter how long I let it sit. Are there any other priming sugars that work "better" than any others?

 

[Revvy]

The other thing is the priming solution that you are using. I currently use corn sugar, but I don't fee like it gives me enough carbonation no matter how long I let it sit. Are there any other priming sugars that work "better" than any others?

If ANY solution isn't giving you the carb level you want, it's not the type you're using, for all intents and purposes a fermentable is a fermentable, it's that you're not using the correct amount.

Search for information on carbing to style.

 

[chazzman]

Personally I use table sugar and never wait more than a week before my
brew is good. I think the advice for waiting three weeks stems from those
who prime with malt extract, because then the primed brew not only has
to carb then, but the green flavor of the newly added malt extract has
to condition out, which will take three weeks just like the orginal brew
did during fermentation.

 

[wyowolf]

How do breweries carb up their bottles?? C02 I guess, just curious how its done...

 

[theDeutscher]

The other thing is the priming solution that you are using. I currently use corn sugar, but I don't fee like it gives me enough carbonation no matter how long I let it sit. Are there any other priming sugars that work "better" than any others?

There's some truth to this, which was news to me. A lot of craft breweries are actually turning to cane sugar to naturally carb their beers instead of corn sugar because corn sugar holds more moisture than cane, resulting in inconsistent carbonation. The corn sugar will absorb more moisture as it gets exposed to air and sits around. I had a 4 pound bag of corn sugar for priming bottles and I did notice that my beers resulted in lower carbonation than my estimates as time went by. I believe it was the Chris White from White Labs that was referring to this.

 

[BigBlueDog]

How do breweries carb up their bottles?? C02 I guess, just curious how its done...

Some bottle condition. Some force carbonate. Some carbonate during secondary fermentation by maintaining the fermentation vessels under controlled pressure.

 

[itsernst]

If ANY solution isn't giving you the carb level you want, it's not the type you're using, for all intents and purposes a fermentable is a fermentable, it's that you're not using the correct amount.

Search for information on carbing to style.

I was never saying that any solution was giving me the carb level i was requesting, I was just saying corn sugar does not seem to be a good fit for what I prefer.

I get that but there definitely is a science to how the sugar, depending on which one you use carbs the bottle. Different sugars will carb depending on many variables. Otherwise there would be a general consensus that everyone use X sugar because it primes the "best".

Obviously different styles call for different amounts of carb, but that isn't to say they call for all of the same carbs.

 

[feinbera]

Idunno, itsernst... at the end of conditioning, carbon dioxide is carbon dioxide, no matter where the yeast are getting the sugars that produced it.

You might see very slight variations in flavor, but think about it in terms of your total grain bill. In a five-gallon batch, you've got somewhere around a 4.5 ounces of priming, or, a quarter pound of corn sugar/cane sugar/extract/honey/whatever, versus pounds and pounds of grain and/or extract. Even in a 1.040 OG lawnmower beer, that's only something like 5% of your grain bill. Unless you're doing something crazy like priming with wort made from black patent, you're not using something that's strong enough to be very noticeable in such a small dose.

 

[unionrdr]

Ok,let me clear up a couple of things. Carbonation & conditioning are two seperate entities. Carbonation takes an average of 3-4 weeks to be produced as pressure in the head space of the bottle. Conditioning,or aging takes about 1 week or more longer with an average gravity ale. That's why a pale ale may be carbed in 3 weeks or less,but the flavors & aromas won't be "conditioned" for another week or more. Fridge time of at least one week will give decent carb/clarity,but 2 weks is best for good head & longer lasting carbonation. Chill haze will appear,if at all,by the time the beers just start to cool down in the fridge. It'll take 3-5 days on average for it to settle like a fog.
As for priming sugars,they must be kept tightly sealed to keep moisture away from them. Otherwise,they can be comprimised as to amount/quality of carbonation. Raw cane sugar,known in the grocery store as demerara sugar,has a nice light brown sugar laced with honey flavor. Gives a bit more complexity & tiny bit of color when used for priming. Great stuff. Try using demerara in place of other sugars in a pale ale recipie,or darker for more flavor. Carbes just fine.
Just remember the old saying with us muzzel loader shooters; keep your powder dry! Same thing with sugars. How do I know these things you may wonder? Science is mostly planning & observation.

 

[itsernst]

Idunno, itsernst... at the end of conditioning, carbon dioxide is carbon dioxide, no matter where the yeast are getting the sugars that produced it.

You might see very slight variations in flavor, but think about it in terms of your total grain bill. In a five-gallon batch, you've got somewhere around a 4.5 ounces of priming, or, a quarter pound of corn sugar/cane sugar/extract/honey/whatever, versus pounds and pounds of grain and/or extract. Even in a 1.040 OG lawnmower beer, that's only something like 5% of your grain bill. Unless you're doing something crazy like priming with wort made from black patent, you're not using something that's strong enough to be very noticeable in such a small dose.

You are absolutely correct, however the variables that contribute to how the sugar becomes carbon dioxide is what I am arguing. Monosaccharids versus Polysaccharides are quite different and their molecule count can change depending on the yeast used in your brew.

 

[BuddyWeiser]

There's also not anywhere near the same amount of oxygen in a freshly bottled beer versus freshly pitched wort.

 

[Bobby_M]

There's also the time it takes for the CO2 to be forced into solution. Some beers are carbonated sooner, but three weeks is a safe estimate.

Myth I say. What exactly do you mean?

 

[Bobby_M]

It only takes a week or 2 for the yeast to eat the priming sugar. The rest of the time allows the gas to be absorbed into the beer. Sort of like force-carbing a keg. You pressurize the keg and put it in the fridge, but you still have to wait a week or 2 for that gas to become carbonation. During the first part of bottle conditioning, the yeast eat the priming sugar and make CO2. Then, during the second part, that gas absorbs into the beer and becomes carbonation.

Myth I say. The process of bottle conditioning is nothing like force carbing. The origin of CO2 in bottle conditioning is IN the beer already at a molecular level which is the opposite of putting CO2 into the head space.

 

[AnOldUR]

Myth I say. The process of bottle conditioning is nothing like force carbing. The origin of CO2 in bottle conditioning is IN the beer already at a molecular level which is the opposite of putting CO2 into the head space.

hmmmm . . . Though I saw something about someone putting a gauge on a bottle and the pressure building and then stabilizing supposedly as the CO2 from the head space went into solution. Or did I misunderstand something?

So would this also debunk the reasons for not bottling in a growler? Seems like the CO2 in suspension once sealed would be putting out the same pressure if it was bottle conditioned or filled from a keg (as long as you didn’t over prime.)

 

[Bobby_M]

hmmmm . . . Though I saw something about someone putting a gauge on a bottle and the pressure building and then stabilizing supposedly as the CO2 from the head space went into solution. Or did I misunderstand something?

So would this also debunk the reasons for not bottling in a growler? Seems like the CO2 in suspension once sealed would be putting out the same pressure if it was bottle conditioned or filled from a keg (as long as you didn’t over prime.)

I commented on this in another thread. My criticism of that experiment was lack of temperature logging. That is the variable that I believe accounts for the spike above equilibrium. Until it is repeated with strict temp control or temp logging along with the pressure, i can't buy in.

 

[AnOldUR]

Until it is repeated with strict temp control or temp logging along with the pressure, i can't buy in.

Sounds like an interesting experiment to try, but do you think that strict temp control is necessary? If you posted a temperature reading along with the pressure reading, could you use a kegging chart to compensate for any minor fluctuations?

How about an extreme experiment? Put a DME solution and some yeast in a high pressure vessel and monitor both pressure and temperature for a week or so? If the CO2 from the fermentation is not going to the head space before being absorbed it should be evident.

I have one of these in the shop that's rated to something like 200psi that might be up to the task with a few modifications.

 

[Bobby_M]

I agree. I'd prefer to see the temp logged along with the pressure. If temp can't be monitored, the lo fi version would to immerse the container including the headspace in a water bath for buffering. Ideally the temp probe would be in a thermowell in the vessel itself.

 

[helibrewer]

Hmmm, seems to me that the CO2 is absorbed into the liquid as it is produced. It doesn't make sense that the CO2 gets produced, then some how gets into the head space then is absorbed. If that was the case we should be able to observe the CO2 bubbles rising into the headspace.

 

[AnOldUR]

If that was the case we should be able to observe the CO2 bubbles rising into the headspace.

I'm not so sure that is the case. During vigorous fermentation in a carboy, I've observed a lot of activity as the yeast convert the sugars into alcohol and C02, but I don't know that I've seen actual bubbles raising through the wort. By the airlock activity, you know that large amounts of C02 are being produced that can't be absorbed because of the temperature and pressure restrictions.

There is probably someone on HBT who could explain this in scientific terms, but I don't have that education and have not been able to find it. For now, I am only looking at it as a mechanical thing. To me, there is logic that either way is possible. I wouldn't argue that some or even most of the C02 is absorbed as it is being formed because of the rate and area over which it is being created during bottle conditioning. But I also haven't ruled out that some of it can make its way into the headspace and is then absorbed over time.

I hope to be able to do the experiment with enough control to satisfy everyone, but I'd still like to hear the science behind why it happens. Is there an instant molecular bonding as Bobby says, or after the sugars are converted, is there a lag time during which some C02 could make its way to the surface?