Kefir is a fermented milk beverage similar to yogurt that’s easy to make and has unique health benefits. It’s thinner than yogurt and I like to use it to make smoothies, like this one flavored with avocado and dates. Unlike yogurt, kefir is the product of a colony of bacteria and yeast called “kefir grains” that is squishy to the touch and looks a little like a cauliflower floret. In this post I’ll tell you how to use it to make kefir.
Here are the grains, rinsed clean. As long as it’s fed some kind of milk (or even sweetened water) regularly, the culture will grow and live indefinitely.
Feeding the grains, and making drinkable kefir in the process, is simple. Add about a tablespoon of grains to a jar with 2 cups of milk—you can use cow, goat, or sheep milk. Put a lid on the jar and leave it out at room temperature for about a day. The culture will consume the lactose in the milk and create lactic acid, which gives the milk a sour taste. The yeast will release carbon dioxide (so don’t be startled if the kefir comes out a little fizzy) and a trace amount of alcohol. (About 1%, or so I’m told. I’ve never noticed.)
The culture will also produce kefiran, a substance that thickens the milk somewhat. The bacteria and yeast use it to build the grains, and it has been shown to have beneficial antimicrobial and healing effects.
The longer you let the culture sit in the same milk, the sourer it will become. I like to leave it for two days, and sometimes forget it for three or more. If it becomes too sour, you can add a sweeter or you can mix it with fresh milk before eating. As the culture grows larger it will put out more kefiran. When you have more than 1 tablespoon of grains per cup of milk, the kefir yogurt can become slimy and unappetizing. At that point you can either start feeding your culture more milk at a time, or you can split the grains and give them away, compost them, or eat them, which is perfectly safe.
Once the kefir is the flavor and consistency you like, pour it through a plastic strainer to separate it from the grains.
I find it helps to gently stir with a wooden spoon to break it up and help it fall away from the grains. Pour the kefir into a new jar and store it in the fridge until you’re ready to eat it.
Put the grains back in the empty jar and feed them fresh milk to start the fermentation process over again. Don’t worry about the kefir that sticks to the sides and the bottom of the jar—it will help inoculate the new milk. If you’re not ready to eat 2 cups of kefir a day, you can let the grains get accustomed to the milk for half or even a full day and then put the jar into the fridge. The cold will slow the fermentation down and the grains will keep for as long as a month or two. Any longer than that and I like to take out the grains and feed them fresh milk.