Why does my beer look like with when I pour?

[lowtones84]

I'm gonna go with the temperature thing here as well as volume. I know when I first started with kits my beers were overcarbed because I used the whole 5 oz. of priming sugar even though I certainly did not get 5 gallons of liquid into the bottling bucket. Sure, 5 oz. for 4.5 gallons or whatever may not seem like it matters much but I think it does. But the temperature (when opening/pouring) thing is definitely a potential culprit too. I didn't know that co2 dissolved more readily in cold liquid when I first started.

 

[jbsayers]

I didn't see this addressed, so I'll chime in. The amount of CO2 in the BOTTLE is directly related to the amount of sugars available to the yeast. The carbonation level in the BEER is a function of temperature and pressure. If the beer is too warm to absorb all of the CO2 produced by the yeast, it goes out of solution into the headspace of the bottle. Pressure increases, volume of CO2 remains the same. Chilling the bottle before serving lowers the temperature of the beer, allowing it to absorb more CO2 again.

I meant in addition to the sugars. That's why I said it is "also" a function of temp and pressure. Good point that inside the capped bottle it is a closed system so the increased headspace pressure forces the CO2 into solution. Like you said, if you don't chill the beer prior to opening, it is no longer a closed system and the CO2 quickly comes out of solution and foaming ensues.

JB

 

[MindenMan]

I meant in addition to the sugars. That's why I said it is "also" a function of temp and pressure. Good point that inside the capped bottle it is a closed system so the increased headspace pressure forces the CO2 into solution. Like you said, if you don't chill the beer prior to opening, it is no longer a closed system and the CO2 quickly comes out of solution and foaming ensues.

JB

I was reading if there was too much head space, the beer would over carbonate, and too little would create too little. I understand that liquid is not compressible and gas is, so will head space really play a factor is carbonation levels?

 

[jbsayers]

I was reading if there was too much head space, the beer would over carbonate, and too little would create too little. I understand that liquid is not compressible and gas is, so will head space really play a factor is carbonation levels?

Again, I am new to brewing. From a basic equilibrium argument, though:

In a capped bottle, the CO2 from priming fermentation has only 2 places to go, into the headspace or into the beer. Pressure is created in the capped bottle because the CO2 diffuses from the beer into the headspace. As more and more CO2 builds up in that headspace volume the pressure rises. As pressure in that volume rises more pressure is exerted on the beer and more CO2 will dissolve back into the beer. When the yeasties run out of sugar, CO2 is no longer being made and eventually the rate of CO2 diffusing into the headspace and dissolving into the beer is the same (equilibrium) and carbing is done.

So in theory with all other things being equal, more headspace will lead to requiring more CO2 to build up in the headpspace to reach x amount of pressure exerted on the beer This will lead to less CO2 dissolved in the beer at equilibrium. Less headspace leads to a less amount of CO2 required to exert x amount of pressure exerted on the beer. This will lead to more CO2 dissolved in the beer.

All of this is a moot point if you do not have enough priming fermentables to properly carb your beer. And if you have too much, overcarbing occurs. This is the most important step in properly carbing your bottled beer.

Make sense?

JB