I'm doing ginger beer sodas by using juices: ginger and lemon juices, cane sugar and natural flavours. I pasteurise the blend by cooking it to 150°F (66°C) for a good minute, then cooling it off and adding sparkling water. Later, bottling and capping.
I've never had any problems, even months later it's all good. But my last batch is for some reason fermenting. I'm not adding any yeast to it, so it's probably fermenting naturally. The glass bottles (beer bottles) are capped, so there is no air coming in, and then I'm not feeding it (adding sugar or ginger like when doing a ginger bug), so I wonder if the fermentation will stop, if so at what point it should, or will it keep fermenting and I can end up with my bottles exploding? I'm about 8.5% Brix in cane sugar.