I just tried to transfer my experience with cider pasteurization to another drink and learned some more tricks. The drink is Malzbier - a traditional non-alcoholic (<0.5%) sweet malty beer from Germany that my family loves (also known as Malta in Latin America and Africa) -
see my thread here.
This drink is actually bottle pasteurized when the fermentation is in full swing (but still only 0.25% alcohol is produced) and much more agressive than cider fermentation (since it is beer with a gravity of 1.056) and is thus very challenging.
Fermentation is so fast at that stage that there is no way to hit the perfect point between to little carbonation and exploding bottles for a full batch. However, after half a dozen explosions under various circumstances (I am not reckless, I never had a single cider bottle explode on me ...), the trick that had my whole last batch successfully pasteurized was:
- let them ferment to the upper end of the desired pressure range
- open the bottles 5-10 minutes to release pressure and capping them right before they enter the water
- keep the water actively between 160 and 170 (never exceeding 170, dropping to 150-155 when inserting the bottles).
This may sound counter-intuitive to first have all the pressure develop and then let it escape but it takes time for the CO2 that is in the beer to escape after opening so there is very nice carbonisation left even after 10 minutes of being open and the overall process is much more controlled.
You might never do something crazy like this with cider which is so much slower than beer, but if you missed the right point and are to high in carbonisation, opening bottles for 5-10 minutes and closing them again before heating will still leave a nice level of bubbles ....