I'm using Red Star champagne yeast to brew natural sodas, but I'm stuck on one issue:
After the room-temp fermentation I move the (2-liter soda) bottles to the refrigerator (38°F) but the fermentation continues at about the same pace. The bottles show significant bulging after just 8-10 hours.
Should I switch yeasts or is there something else I can do to slow the fermentation so that I can safely move the product into glass bottles?
The thing about champagne yeast (and other wine yeasts) is that they have been selected to eat a lot a of fermentable sugar with little nutrients around. Another facet of this is, even though the yeast is recommended for a particular temperature doesn't mean it won't ferment outside that range, or wake up later to finish the job.
As long as there is live yeast and a bunch of sugar around, you can't really "safely move the product into glass bottles". There's a reason champagne bottles are so heavy, and the cork is held in with wire!
People that make hard cider have similar problems, maybe their methods would work for you.
It's possible that the yeast isn't going to sleep fast enough. You could try putting the bottles into the freezer for a short time before refrigerating in order to reduce the temperature rapidly.
