Raising/dropping Temp At The End Of A Ferment

[hazard]

Ok thanks.. that's clear now.

Jonez, just think of your fermenter as a big bottle of coke. If you take the lid off a cold bottle, CO2 escapes, but there will still be some remaining carbonation. If you leave it in a warm place, it will continue to lose CO2 until equilibrium is reached (i learnt this in high school chemistry over 30 years ago so I'm a bit rusty, its got to do with partial pressure). If it gets hotter, more CO2 is lost until a new equilibrium point is reached.
But - if you put it back in the fridge - it cools down but will NOT carb up again. If you put it in a fridge which contained a CO2 atmosphere then yes, it wold re-ab absorb CO2 but this is highly unlikely ....
So as butters says, CO2 level is based on highest temp that is reached.

 

[Jonez]

Jonez, just think of your fermenter as a big bottle of coke. If you take the lid off a cold bottle, CO2 escapes, but there will still be some remaining carbonation. If you leave it in a warm place, it will continue to lose CO2 until equilibrium is reached (i learnt this in high school chemistry over 30 years ago so I'm a bit rusty, its got to do with partial pressure). If it gets hotter, more CO2 is lost until a new equilibrium point is reached.
But - if you put it back in the fridge - it cools down but will NOT carb up again. If you put it in a fridge which contained a CO2 atmosphere then yes, it wold re-ab absorb CO2 but this is highly unlikely ....
So as butters says, CO2 level is based on highest temp that is reached.

Hazard
It is all understandable. I knew more CO2 will be released at higher temps and so on. However we have to admit we are using an approximation method here. One example is a case where the higher temperature occurs at the beginning of the fermentation. Let’s say that the temp is then reduced for any given reasons and the most significant amount of CO2 is then produced at that lower temp. If the variations in temp are small, the differences may be neglect able. But everyone here does different, so it is always good to hear their opinions

edit spelling again

 

[crundle]

Thanks for bringing up that question Jonez, I keg so I didn't know the answer, but now after hearing the explanation I do.

When I was bottling, I had my fair share of bombs, but my temperature control consisted of brewing downstairs at my parent's house in the Adelaide Hills, where it is partially built into the rock on a hill, so the temperatures were very steady the whole year around, but that was well before I learnt about the importance of fermentation temperatures and how they impact on bottling.

Kegging does make the whole thing simpler - set the pressure according to the kegerator temperature to hit your desired carbonation level and then bottle from the keg for clear perfectly carbonated beers.... in theory!

Crundle

 

[HoppingMad]

Noticed you have a Hefeweizen going.

Depending on the yeast you're using, some people will push the temp up towards the end to get more banana esters (to around 23/24 degrees). Don't do this unless you have checked the specs on your yeast first though! Some yeasts won't like going this high. But something like a Wyeast Weihanstephaner will give you more banana clove when pumped a little higher. Haven't tried it on a Fermentis WB-06, but have heard of it being done too.

If you like fruity esters in your beer, then these higher temps work. This is particularly so in a lot of Belgian styles and Saisons where it is common to ferment at regular ale or high ale temps then rocket the temp up to finish it off. It is a bit of a balancing act though - go too high and overstress the yeast and you will get nasty fusel alcohol notes in your beer - so follow the temp ranges recommended by the yeast supplier website.

Hopper.