The chemistry of bottle conditioning

[Mishka]

Hi everyone,
just found this amazing forum - what a great resource! Anyway, I've always wondered what happens during bottle conditioning once the yeast has already created an adequate amount of CO2. I've heard that too much bottle conditioning makes bottles explode unless you refrigitate them at the proper time. But what occurs inside the bottle during this stage to make the yeast stop producing too much carbonation? And why can you store these bottles at room temp. after a short refrigiration process and not have them explode? I'm guessing enzyme kinetics is somehow involved but that's just a wild guess.

Thanks

 

[Orfy]

My simplistic understanding is that the yeast exhausts it's food (priming sugar) and the carbonation stops, the refrigeration will stop the yeast doing it's work so will halt or slow down any further carbonation.

 

[user 574]

Yep, what Orfy said. They can become bombs if too much sugar was used or the fermentation was not complete. Otherwise theres just enough food there for them to create the right amount of co2

 

[Mishka]

That's cool. I never realized the 3/4 cup rule was so important. By the way, does the amount of bottling sugar used depend at all on gravity or beer style?

 

[user 574]

Don't believe so, think it's all about volume. I've always only used the 3/4 cup / 5oz.

 

[El Pistolero]

That's cool. I never realized the 3/4 cup rule was so important. By the way, does the amount of bottling sugar used depend at all on gravity or beer style?

Some styles (like hefe's) are traditionally more bubbly. I use 1 1/4 cup DME for most beers, but 1 1/2 cup DME for hefeweizens.

 

[user 574]

I never used DME, guess the qty used is a bit higher than corn sugar then hey? I typically just grab the 5oz pre-packaged corn sugar from my hbs when bottling.

 

[Darth Konvel]

DME is not as fermentable, so you need more of it to get the same amount of CO2. Regardless of what you use, if you use the right amount, you don't have to refrigerate them in order to avoid bottle bombs.

Other then CO2 production, the yeast will process different byproducts, and the flavors mellow out and meld. I'm honestly not sure how this is described from a chemistry standpoint, I just know it tastes better over time

 

[Mishka]

Thanks for the great responses. Just like desertBrew I have only used those corn sugar packages from the store but I might try the DME method next time just to experiment. I've certainly noticed the positive effects of bottle aging ("lagering"?) my beer for several weeks - kinda balances the taste. Though, I've talked to several commercial brewers who really push the "fresh is best" thing.

 

[El Pistolero]

Thanks for the great responses. Just like desertBrew I have only used those corn sugar packages from the store but I might try the DME method next time just to experiment. I've certainly noticed the positive effects of bottle aging ("lagering"?) my beer for several weeks - kinda balances the taste. Though, I've talked to several commercial brewers who really push the "fresh is best" thing.

Most commercial brews are filtered and pasturized, thus won't "condition" in the bottles...they'll only get worse once bottled, thus the emphasis on freshness.

 

[Mishka]

Most commercial brews are filtered and pasturized, thus won't "condition" in the bottles...they'll only get worse once bottled, thus the emphasis on freshness.

That makes sense. I just visited the Unibroue website and they make a huge deal about how they bottle-condition all their beers and you can cellar each one for X years. Granted all their beers have high ABV so cellaring isn't a problem.

 

[homebrewer_99]

I agree with every comment mentioned so far.

As far as your question "why can you store these bottles at room temp after a short refridgeration process and not have them explode?", is a good one.

I, for one, do not know the answer to this question. Logically, the yeast should re-animate when it gets warm again.

On the other hand, I have cases of bottles that have NEVER been re- (wrong term) fridgerated, or cold for that matter. Some of them are over 1 year old. They have a nice head, do not gush, and taste good.

I suppose the most important aspects are, as already mentioned, that the fermentation was complete prior to bottling and they are not over-primed.