Different approaches to bottle priming

[Chalkyt]

Hello Beer People…

I am from over the fence in the HBT Cider Forum where there has been a bit of discussion on bottle priming for carbonation. There is a difference between the “rule of thumb” that is commonly used for cider, and various on-line beer priming calculators, so I wonder if anyone in your world can shed some light on why the difference.

For cider, there is a “rule of thumb” for bottle carbonation of 2.5 volumes of CO2. This is suggested by Andrew Lea in his classic book Craft Cider Making. The recommended amount is approximately 10 grams of sugar per litre which produces 2.5 litres (i.e. volumes) of CO2. Empirically this works since sugar ferments into 47% CO2 which has a density of 1.977g/L at 0C, therefore the amount of priming sugar needed for 2.5 vols is 1.977 x 2.5/0.47 = 10.5g of sugar. Even using the density of CO2 at 15C the amount of sugar needed is 9.9g, so 10g is “near enough”).

However, using one of the on-line beer carbonation calculators (Brewer’s Friend, Northern Brewer, etc.), the suggested sugar for 2.5 volumes of CO2 per litre is around 6g of sugar Based on the approach above, this amount of sugar will only result in about 1.5 volumes.

In each case it is assumed that there will be a bit under a volume of CO2 in the beer or cider resulting from fermentation, but this doesn’t contribute to the “fizz”. The priming sugar CO2 is what makes the “fizz”.

I understand that the on-line calculators are generally based on Dr Michael Hall’s multiple regression formulae covered in his Zymurgy Summer 1995 article. Therefore this approach has pretty impressive credentials.

So, can anyone suggest why there is a difference between the two approaches. Are the calculators simply not suitable for cider (which BTY doesn’t get listed in the calculator beer types) or is there something in the beer biochemistry process that explains it?

Any comments are welcome.

Cheers!

 

[Miraculix]

Of course does the dissolved co2 from fermentation contribute to the fizz.

If you want 2.5 and you already have 1 in solution, you only need additional 1.5.

 

[DBhomebrew]

And the whole reason why those calculators require the beer temperature. Warmer beer (or cider) will hold less CO2 from fermentation than colder beer (or cider). The calculator will account for the difference.

 

[mac_1103]

So I found an online version of Lea's book. I haven't read the whole thing, but I did notice that he presents his rule of thumb for carbonation without any math. Now he obviously understands the science of fermentation very well and knows that there is some CO2 dissolved in the cider before conditioning, so I'm left to naively wonder if the difference just might be as simple as he likes his ciders a bit fizzier - i.e., with 2.5 volumes of added CO2 rather than 2.5 volumes of total CO2. The problem with that notion of course, is that standard long neck beer bottles really should not be counted on to safely hold more than about 3 volumes total CO2.

I am not aware of intrinsic differences between beer and cider (or the respective processes for making them) that would change the amount of residual CO2 at the end of fermentation, but that doesn't mean there aren't any.

 

[DuncB]

I would want at least 3 vols of CO2 in bottled cider, much like sparkling wine it needs that extra effervescence.
I use champagne bottles which can cope with higher vols than this. They cope with highly carbonated belgian beers as well.

 

[Chalkyt]

Thanks for the replies...

It just seems to be a matter of interpretation and understanding what is being calculated.

The various calculators recommend carbonation for different types of beer. The recommendations include the CO2 already in the beverage at atmospheric pressure which doesn’t contribute to the fizz. So, in a simple case of requiring 2.5 volumes, the recommended sugar dose will only result in 1.6 volumes of fizz. If 2.5 volumes of fizz is required, then the target carbonation that should be entered into the calculator is 0.83 + 2.5 = 3.3 volumes.

For whatever reason, 2.0 – 2.5 volumes of CO2 seems to be the popular level of carbonation for cider. It may well be that 10g of sugar is a more precise measure of the long-standing rough guide of 2 teaspoons of sugar per litre for carbonating.

I guess some of the confusion came from a discussion between authors Andrew Lea and Claude Jolicoeur on another forum back in 2011. Although I have posted this information before, it is worth repeating. An extract from the discussion is…

“what you actually measure in a soft drink is the pressure over 1 bar - i.e. gauge pressure, not absolute”…

“you must saturate your cider with CO2 to get up to the 1 atm of normal atmospheric pressure that we all live under. Only after that will there be 'carbonation'. The gauge pressure is the bottle pressure in excess of the 1 atmosphere required for saturation that takes place without carbonation being apparent.”​

Cheers!

 

[Miraculix]

Thanks for the replies...

It just seems to be a matter of interpretation and understanding what is being calculated.

The various calculators recommend carbonation for different types of beer. The recommendations include the CO2 already in the beverage at atmospheric pressure which doesn’t contribute to the fizz. So, in a simple case of requiring 2.5 volumes, the recommended sugar dose will only result in 1.6 volumes of fizz. If 2.5 volumes of fizz is required, then the target carbonation that should be entered into the calculator is 0.83 + 2.5 = 3.3 volumes.

For whatever reason, 2.0 – 2.5 volumes of CO2 seems to be the popular level of carbonation for cider. It may well be that 10g of sugar is a more precise measure of the long-standing rough guide of 2 teaspoons of sugar per litre for carbonating.

I guess some of the confusion came from a discussion between authors Andrew Lea and Claude Jolicoeur on another forum back in 2011. Although I have posted this information before, it is worth repeating. An extract from the discussion is…

“what you actually measure in a soft drink is the pressure over 1 bar - i.e. gauge pressure, not absolute”…

“you must saturate your cider with CO2 to get up to the 1 atm of normal atmospheric pressure that we all live under. Only after that will there be 'carbonation'. The gauge pressure is the bottle pressure in excess of the 1 atmosphere required for saturation that takes place without carbonation being apparent.”​

Cheers!

While being technically correct, the assumption that "fizz" is generally measured as the volume above the atmospheric pressure is wrong.

All the online calculators that I know of and all the literature that I know is always accounting for the whole amount of dissolved co2.

 

[mac_1103]

While being technically correct, the assumption that "fizz" is generally measured as the volume above the atmospheric pressure is wrong.

All the online calculators that I know of and all the literature that I know is always accounting for the whole amount of dissolved co2.

I'm not sure there really is a disagreement here. We all know that our beverages contain CO2 at the end of fermentation, but I also think that we all would describe them as "flat" (or still) right out of the fermenter. It takes additional dissolved CO2 before we perceive carbonation (or fizz).

 

[Miraculix]

I'm not sure there really is a disagreement here. We all know that our beverages contain CO2 at the end of fermentation, but I also think that we all would describe them as "flat" (or still) right out of the fermenter. It takes additional dissolved CO2 before we perceive carbonation (or fizz).

Yes, that is correct.

It's just that the quoted person who wrote the book said that we don't account for that and that we simply add 2.5 volume to what's already in there and that this is the way that everyone thinks in general.

However, everybody else seems to not ignore the dissolved co2 and instead aim for a total of 2.5 volumes. That's a difference of 3.5 to 2.5.

After all I agree that cider is usually more sparkling than beer, so 3.5 volumes would still make sense if we ignore the weird way he got there.

 

[mac_1103]

I agree that cider is usually more sparkling than beer, so 3.5 volumes would still make sense if we ignore the weird way he got there.

And use the right bottles!

 

[Miraculix]

And use the right bottles!

I'm thinking of the Aspall bottles right now. They are beautiful and the cider has lots of fizz.