Originally Posted by Daze
yes you are more likely to get gushers, but you are also less likely to get bombs. It is not just the co2. If you bottle a still cider ice cold and then bring it up to room temp there will be a fair amount of pressure in the bottle just from the expansion of the liquid as it warms, then add max co2 to that mix and the pressure is high. pasteurizing is a risky process if there is any chance of to much pressure, so why would you increase your risk by releasing the pressure and recapping when cold?? doing it warm will still provide tons on co2 but will reduce the chance of bottle bombs.
the density of liquids is notoriously stable through temperature ranges. water is famously most dense (ie smallest volume per unit mass) at 4 degrees; fridge temp, which is also the reference point for water mass: 1 gram of water at 4 degrees is 1 cc., or 1 ml.; density = 1.0000 (g/ml)
at 20 degrees, room temp, (farenheight fans- come on, modernize!) density of water is 0.9982. if you have 350 ml (beer bottle) of water raised from 4 to 20 degrees the change in volume therefore is 0.6 ml. the normal head space in a beer bottle is 20-25 ml. properties of ethanol/water mixes are different and harder to calculate but change in density of 5 or 10% ethanol is very similar to water. compared to the relatively great change of pressure from expanding gas in a very small space and the release of gas from solution this change is negligible.
heating a sealed bottle is always dangerous, i agree, but it is also a pointless endeavor if you are not preserving carbonation! if you just want to kill the yeast then heat with the bottles open, or pass the cider through a coil submerged in hot water. the idea is to walk the two fine lines between dangerous gas levels / not enough fizz, and and too-high heat / unsafe low temps. that has been the whole point of pappers' sticky, where he determined that, if you have a bottle of cider which is perfectly carbed when it has been in the fridge and equilibrated to fridge temps, then this bottle will safely survive the heating conditions he describes. however you get to that point, once you are there the bottle is at least deemed safe enough to heat following the pappers protocol, but i agree that you would need to use caution in getting the bottles safely up to the kill temperature.
holy dennis did i really just type that much crap... sorry. too much coffee. didn't mean to be a dick, just after facts. going to brew a porter now