squarecurls
Is the yellow on the grains themselves or on the brewed/brewing kefir?
If they are on the grains, it is butterfat and it needs to be removed. Have you been to Dom's site? He gives directions on how to do that, but I just used my fingers to remove it as there was only a little bit on one of the grains.
If it is on the brewed/brewing kefir, I don't know what to think. I'd probably just stir it all up and see how it looked later. ???
SC