Question about philly sour bottle conditioning / possible bottle bombs

[viskrikke]

I bottled my cider, made with philly sour yeast, at 1.000 (its been at that reading for 5 months in bulk age). I now added some EC 1118 Prise de Mousse yeast and 42 gram of sugar to my 5 liter for bottle carbonation (3 vol. CO2) as per usual.
I was wondering however, since my other ciders (not philly sour yeast) tend to go dryer at 0.990, do I have a chance I created bottle bombs? Will the prise de Mouse eat through the 42 gram and also the remaining gravity points?
I bottled in champagne style bottles with plastic corks and wire cages.
Any help is appreciated,

 

[Chalkyt]

My view is that it should be fine. My reasons are...

Champagne bottles are generally rated at 6g/v to 7g/v (i.e 6-7 volumes of gas) and probably have a fairly high margin of safety built into this rating. In my (unfortunate) experience, the corks and wires fail before the bottles do... hence the interesting spray pattern on the ceiling when a batch of my "rhubarb champagne" matured a bit too much. SWMBO didn't think too much of it, though!

Secondly, getting a bit technical... SG falling below 1.000 is usually the result of high ABV rather than more sugar being consumed, since the SG of alcohol is less than water so the final alcohol/water SG will be less than 1.000. Also, sugar is only about 80% of the compounds in cider that affect SG, the rest is non-fermentable compounds so at 1.000 for several months you can be confident that all of the sugar is consumed. A stable SG above 1.000 would be a function of the yeast (such as SO4) and in that case you could have a bit of sugar left.

Using the "rough rule of thumb" that a 2 point gravity change will result in 1 volume of CO2, if you really had SG 0.010 worth of sugar left (unlikely) plus your addition of 42g of sugar would still only result in the equivalent of SG1.013 which would result in 6.5 vols of CO2 if it was all fermented.

If you still have concerns, try rigging up a pressure gauge to measure bottle pressure. There are several ways of doing this. I simply have a gauge screwed through a Grolsch type closure but there are a few posts of alternative versions on the forum. I use my setup to monitor pressure in bottles that I want to pasteurise for sweet carbonated cider. I simply pasteurise when the gauge shows two bars (around 30 psi) which is 2 atm at room temperature.

Hope this helps.

 

[viskrikke]

My view is that it should be fine. My reasons are...

Champagne bottles are generally rated at 6g/v to 7g/v (i.e 6-7 volumes of gas) and probably have a fairly high margin of safety built into this rating. In my (unfortunate) experience, the corks and wires fail before the bottles do... hence the interesting spray pattern on the ceiling when a batch of my "rhubarb champagne" matured a bit too much. SWMBO didn't think too much of it, though!

Secondly, getting a bit technical... SG falling below 1.000 is usually the result of high ABV rather than more sugar being consumed, since the SG of alcohol is less than water so the final alcohol/water SG will be less than 1.000. Also, sugar is only about 80% of the compounds in cider that affect SG, the rest is non-fermentable compounds so at 1.000 for several months you can be confident that all of the sugar is consumed. A stable SG above 1.000 would be a function of the yeast (such as SO4) and in that case you could have a bit of sugar left.

Using the "rough rule of thumb" that a 2 point gravity change will result in 1 volume of CO2, if you really had SG 0.010 worth of sugar left (unlikely) plus your addition of 42g of sugar would still only result in the equivalent of SG1.013 which would result in 6.5 vols of CO2 if it was all fermented.

If you still have concerns, try rigging up a pressure gauge to measure bottle pressure. There are several ways of doing this. I simply have a gauge screwed through a Grolsch type closure but there are a few posts of alternative versions on the forum. I use my setup to monitor pressure in bottles that I want to pasteurise for sweet carbonated cider. I simply pasteurise when the gauge shows two bars (around 30 psi) which is 2 atm at room temperature.

Hope this helps.

Thanks for the explanation!

 

[DuncB]

I've heard of some people doing one bottle in their batches with a PET bottle, these can be squeezed to estimate pressure ( not that accurate ) but if they fail tend to rupture or lose their top without danger, also as plastic is thin they might condition a bit quicker and give you some warning.
But that said I reckon you'll be safe with your bottles, I bottled my elderflower fizz under pressure at 3 vols and added sugar and no failures of the crown caps.

 

[teddyearp]

If you really want to be cool when you bottle carb, install one of those gauges from McMaster-Carr in the cap of your plastic bottle that Mylar posted in the pasteurization sticky. I let mine get to about 35-40psi and then cold crash into the fridge. Takes all the guess work out of it and comes out perfect.

 

[Chalkyt]

You will find one of Mylar's posts about using a gauge on 19 Nov 2020, just use the search function at the top of the forum. I also have a post on 11 Nov 2020 (inspired by Mylar's earlier posts) which shows my setup using a Grolsch bottle and wire bail stopper. The downside of the Grolsch bottle approach is that the seals can leak at 70 psi or so (about 4.5 vols of CO2).

The advantage of the gauge is that if you are wanting to stop fermentation above 1.000 (e.g. for a sweeter cider) you can bottle early and monitor pressure to pasteurise to stop fermentation when the CO2 is at the level you want. I pasteurise at about 2 volumes of CO2 (32 psi or 2 bar) which gives a "just right" carbonation for me.

Using the firmness of a soda bottle works fine up to about 2 -2.5 volumes of CO2. After that the bottle is hard, so if you are after high CO2 levels like champagne, 3 vols, 4 vols, etc can't be differentiated because a hard bottle is a hard bottle.