MightyPinecone: Thanks, now i know what to expect. :)
Bread, warmth AND sugar, those yeast fungi will be in yeast heaven!
Thats the trick. If you keep it open, you get alcoholic beverage. But if not - they suffocate from own gas and pressure.
Just remember, that the pressure will be initially high, thus perhaps regular PET bottles might not keep it...
I use large glass bottles (from wine plantation) with screwable caps. Perhaps, it might be a good idea to slightly open the bottles, thus the excessive pressure can escape in first 5 hours - to about same degree one unscrews the cola bottle to let a bit of excessive pressure out. But close them tight after 5 hours and put in the cooler (but not freezer!) to keep pressure low... the process should then extend to about 2 days, but it would be more stable/controllable.
Kwas should not be alcoholic, the yeast is for gas, its should not consume sugar. Its tastes like cola, but a bit different.