General Information - How do you know if the grains are healthy?
Kefir grains are very resilient and will strive to maintain their health at all times. As long as your grains are converting milk to kefir that is not 'off' they are just fine. They may get stressed and change shape or smell a bit (more yeasty or more stringy looking), but they will bounce right back given the right conditions. They range from creamy white to a dark ivory and coiled brain-patterned balls to bumpy ribbons. Even when they are not growing they can still produce a healthy drinkable kefir (such as in soy or almond milk), though its best to give them optimal conditions so they can grow.
