Interesting start to bottle conditioning

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Georgedgerton

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After a lengthy break I finally put a couple of brews down. The first was a 22 litre all grain brown ale, the second a ten litre experiment with a mini mash and LDME base. The AG 22 litre batch was crash chilled given the gelatin finings treatment and put in a Corny keg and gassed. The experimental batch was put in plastic beer bottles and given the bottle condition usual start. Having a couple of litres of the 22 litre batch left over I decided to put that in plastic bottles and condition with the others. I thought being very cold and after fining it might be a bit of a slow start for the yeast to wake back up. Next day the ten litre batch that had been fermented at 19 C and bottle at that was showing some signs of carbing up with a bit of pressure evident in the plastic bottle. The batch that I thought was going to make a slow start is well ahead of the others with considerable pressure evident in the plastic bottles. Same yeast used in both batches by the way.
So why on earth would that be?
 

Feldon

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The difference in bottle pressure between the two beers is possibly related to the different amount of CO2 that was dissolved in the beer when you bottled them.

Couple of key points: First, the colder a beer is the more CO2 it can hold in solution - warm it up and the CO2 will want to start coming out of solution to atmosphere, or into the head space of the bottle, or whatever. Secondly, a warm beer will ‘fizz’ off CO2 quicker when agitated than a colder beer of equivalent carbonation given equivalent agitation. The colder beer gives up its CO2 less vigorously.

So, the 10 liter batch wasn’t cold crashed and was bottled at room temp. The amount of CO2 in the beer, acquired during the fermentation process, would have been at about the maximum it could hold at that temp. And then the agitation of bottling (minor splashing etc that can’t really be avoided) would have caused some of this dissolved CO2 to be gassed off out of solution during the bottling process.

The 22 L batch of brown ale also acquired CO2 during its primary fermentation. But by cold crashing this CO2 was more ‘locked in’ because at this lower temp the beer has potential to hold much more CO2 than it has. And if agitated during the bottling process it will be more reluctant to give up the CO2 than it would at room temp. If those sealed bottles of cold beer were left to come up to condition at a room temp higher than the previous fermentation temp, the beer would give up some of its dissolved CO2 to the head space thus increasing pressure in the bottle.

My 2 cents (but wondering if you had two different yeasts at work in the two different beers - that might explain things too)
 
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What was the highest temperature of the 22L batch after the apparent end of fermentation? Feldon is right about dissvolved CO2, but whether that wholly explains the difference is hard to tell. Fining leaves yeast behind, and activation is a possibility. In any event, an advantage of plastic bottles over glass is they don't throw much shrapnel if they break.
 

Georgedgerton

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The difference in bottle pressure between the two beers is possibly related to the different amount of CO2 that was dissolved in the beer when you bottled them.

Couple of key points: First, the colder a beer is the more CO2 it can hold in solution - warm it up and the CO2 will want to start coming out of solution to atmosphere, or into the head space of the bottle, or whatever. Secondly, a warm beer will ‘fizz’ off CO2 quicker when agitated than a colder beer of equivalent carbonation given equivalent agitation. The colder beer gives up its CO2 less vigorously.

So, the 10 liter batch wasn’t cold crashed and was bottled at room temp. The amount of CO2 in the beer, acquired during the fermentation process, would have been at about the maximum it could hold at that temp. And then the agitation of bottling (minor splashing etc that can’t really be avoided) would have caused some of this dissolved CO2 to be gassed off out of solution during the bottling process.

The 22 L batch of brown ale also acquired CO2 during its primary fermentation. But by cold crashing this CO2 was more ‘locked in’ because at this lower temp the beer has potential to hold much more CO2 than it has. And if agitated during the bottling process it will be more reluctant to give up the CO2 than it would at room temp. If those sealed bottles of cold beer were left to come up to condition at a room temp higher than the previous fermentation temp, the beer would give up some of its dissolved CO2 to the head space thus increasing pressure in the bottle.

My 2 cents (but wondering if you had two different yeasts at work in the two different beers - that might explain things too)
Good point, i think you're probably right on the ma
 

Georgedgerton

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What was the highest temperature of the 22L batch after the apparent end of fermentation? Feldon is right about dissvolved CO2, but whether that wholly explains the difference is hard to tell. Fining leaves yeast behind, and activation is a possibility. In any event, an advantage of plastic bottles over glass is they don't throw much shrapnel if they break.
the temperature even though one was in in a controlled environment and the other wasn't were pretty close together. I think what feldon said is probably close to the thruth
 
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