Tania,
I LOVE kefir. I responded to your other post about it. I don't make my own though. Maybe when I am off from work this summer I will try it. I actually cook and bake with leftover kefir.
This is from the wiki cookbook online, it describes it better than i could:
Kefir as leavening agent
Kefir can be used as a
leavening agent when baking
bread, because it contains active yeasts and bacteria. It can be used directly in a recipe, by replacing the yeast and half the water with kefir. Recipes that specify
buttermilk or
yoghurt can be made just as well (or better!) with kefir.
Alternatively, kefir can be used to create a
sourdough starter. Add ˝ teaspoonful of kefir to ˝ cup flour and ˝ cup water, mix well, and set aside to ferment for 12 - 24 hours.
I also use kefir in muffin mix. You can google "kefir muffin recipe" for some good ideas.
And here is a link with some good cooking with kefir recipes, I tried the raspberry coffee cake one and it is good:
http://www.royalkefir.com/cooking-and-baking