Postby kagy » Mon Jan 25, 2016 7:10 pm
I am brand new to the kefir culture, but have extensive experience with other cultures, specifically sour dough, yogurt and beer.
It's been my experience that cultures such as these are very hearty, and difficult to kill. High heat (above 110ºF) for a prolonged period, or high alcohol are two ways to do so. But yeasts won't produce enough alcohol to kill themselves. They will stop converting sugars into alcohol after a point, and then it is impossible to raise alcohol content above a certain point without adding more sugar.
So letting a water kefir sit for a longer period of time in order to diminish sugar to the lowest point possible should not completely kill the kefir crystals, but it may be that you'd have to revive them in the next batch by putting them in a fresh water/sugar solution, letting sit for a day or two, and repeating.
All that said, I'd love to know the glycemic index for a finished water kefir. My wife is diabetic, and I assume that the drink is too sweet for her.