I don't do kefir anymore - I decided awhile ago that I didn't like it well enough to continue to bother with it (though the chickens really did like it ). But I have dehydrated, and rehydrated, it in the past. I remember that it took a week or so to get the grains "back on line", and that, during that time, the milk smelled awful - too bad to even give the chickens! But it evened out after a bit, and was back to its regular smell and taste. (I still have some dehydrated grains, just in case I decide to give it another try)