Step 1

Measure milk kefir grains into a clean, half-gallon jar.

Step 2

Add one quart of milk.

Step 3

Cover the mouth of the jar with a coffee filter, tea towel, or cheesecloth and secure with a rubber band.

Step 4

Let the milk kefir sit at room temperature until it is your desired thickness and sourness. This usually takes between 12 and 36 hours, based on your preference and the temperature in your kitchen. Don’t worry about leaving it out for 36 hours. The longer fermentation just means thicker and more sour kefir with more probiotic benefits.

Step 5

After fermentation, strain out the kefir grains. Use the kefir immediately or keep it in cold storage (below 50°F), with a lid, for up to two weeks.

Step 6

The kefir grains can be used to start a new batch of milk kefir or stored in the refrigerator. Simply place the grains in a small glass jar and pour milk or milk kefir over them to cover.