Milk kefir is an easy sell for anyone who loves yogurt, which I most definitely do. Kefir is tangy, about as thick (and creamy!) as a smoothie, and full of those good-for-you probiotics we hear so much about. Think of milk kefir as drinkable, pourable yogurt. Even better, you can skip the grocery store and make it yourself right on your kitchen counter.
Fresh milk kefir, strained and ready to drink
What Is Milk Kefir?
Milk kefir is a fermented dairy product similar in many ways to yogurt and buttermilk. It's how kefir is cultured that makes it really unique — instead of heating the milk, adding a culture, and keeping it warm as you do with yogurt, all you need to make milk kefir are kefir grains.
Kefir grains are not really grains at all (don't worry, gluten-free folks!). These "grains" are actually tiny, rubbery, knobby-looking cell structures that are home to the bacteria and yeast that ferment the kefir. These grains are the milk kefir equivalent to the scoby used to make kombucha.
How Does It Work?
It's extremely simple. Add about a teaspoon of these kefir grains to a cup of milk, cover the glass, and let it sit out at room temperature for about 24 hours. During this time, the healthy bacterias and yeast in the kefir grains will ferment the milk, preventing it from spoiling while transforming it into kefir.
When done, the kefir will have thickened to the consistency of buttermilk and taste noticeably tangy, like yogurt. Strain out the grains so you can use them in another batch, and the kefir is ready to drink.
Oh, that's another thing! As long as they stay healthy, you can reuse kefir grains indefinitely to make batch after batch of kefir. And the best way to keep them healthy is to keep making kefir! You can make a new batch of kefir roughly every 24 hours (the temperature of your kitchen can affect the exact time) just by putting the kefir grains in a fresh cup of milk. Over time, the grains will multiply and you can either discard the extra or share it with friends. You can also take a break from making kefir by putting the grains in a new cup of milk and storing this in the fridge.
Are There Health Benefits?
Yes! Like yogurt and other cultured and fermented products, milk kefir is full of probiotics, which aid healthy digestion. The fermenting process also changes some of the protein structures in the milk, making it easier to digest. Some people who can't tolerate milk often do better when drinking milk kefir.
What Milk to Use?
The kefir grains work best with whole-fat animal milk, which is to say, whole fat milk from cows, goats, and sheep. You can successfully make kefir with 2% and reduced fat milk, but if you notice that your grains are behaving sluggishly or taking longer and longer to ferment the milk, pop them back in a jar of whole milk to refresh them. You can also use raw or pasteurized milk, but avoid ultra-high temperature (UHT) pasteurized milk.
If you're looking for a non-dairy option, try making the kefir with coconut milk. Since coconut milk lacks the same proteins and nutrients as animal milk, the kefir grains will lose their vitality after a little while. To refresh them, put them back in some animal milk for a batch or two. Unfortunately, I haven't had success with making milk kefir with almond milk, soy milk, or other dairy-free milks.
What Can I Do With Milk Kefir?
You can drink milk kefir just as it is, straight-up! You can also add milk kefir to smoothies, lassis, and other drinks just as you would use yogurt or regular milk.
Kefir is fantastic for baking, too! Use it in place of yogurt, milk, or buttermilk in any recipe you make.
Is This Safe? What Can Go Wrong?
The practice of making milk kefir has been around for several thousands of years, and was traditionally a way of preserving fresh milk and making it last longer. This is to say, yes, it's safe. The healthy bacterias and yeasts in the kefir grains box out any unhealthy or spoiling bacterias that would otherwise take hold of milk left at room temperature.
I've been making milk kefir for years now, and the only real concern I've run into is room temperature. Kefir grains like an average room temperature of about 60°F to 90°F. Below 60°F, the grains become sluggish and can go into hibernation — they're still fine, but it might just take longer to make the kefir. Above 90°F, the milk spoils more quickly than the grains can culture it, and this creates an unsafe environment for the grains (and you). Avoid making kefir on very hot summer days if you don't have air conditioning.
Also, be sure to make your kefir in a glass jar as the grains can become weakened by exposure to metal. Brief exposure, like using a metal strainer or stirring with a metal spoon, is fine.
Where to Find Kefir Grains
The best place to find kefir grains is from a kefir-making friend! The grains start to multiply after a while and anyone who makes it regularly will have extra grains to spare. If you don't have such a friend, I recommend these sources:
1 cup milk, preferably whole fat (see Recipe Notes)
1 teaspoon active kefir grains (See Recipe Notes)
1 pint-sized glass jar
Cheesecloth, paper towel, or clean napkin
Small strainer (preferably plastic, but metal is ok)
Storage container with lid
Note: Avoid prolonged contact between the kefir and metal both during and after brewing. This can affect the flavor of your kefir and weaken the grains over time.
Combine the milk and the grains in a jar: Pour the milk into a clean glass jar (not metal) and stir in the kefir grains. The milk can be cold or room temperature, either is fine.
Cover the jar: Cover the jar with cheesecloth, a paper towel, or a clean napkin and secure it with a rubber band. Do not screw a lid onto the jar as the build up of carbon dioxide from the fermenting grains can cause pressure to build in the jar, and in extreme cases, cause the jar to burst.
Ferment for 12 to 48 hours: Store the jar at room temperature (ideally around 70°F) away from direct sunlight. Check the jar every few hours. When the milk has thickened and tastes tangy, it's ready. This will usually take about 24 hours at average room temperatures; the milk will ferment faster at warmer temperatures and slower at cool temperatures. If your milk hasn't fermented after 48 hours, strain out the grains and try again in a fresh batch (this sometimes happens when using new kefir grains, when refreshing dried kefir grains, or when using grains that have been refrigerated).
Strain out the kefir grains: Place a small strainer over the container you'll use to store the kefir. Strain the kefir into the container, catching the grains in the strainer.
Transfer the grains to fresh milk: Stir the grains into a fresh batch of milk and allow to ferment again. This way, you can make a fresh batch of kefir roughly every 24 hours. To take a break from making kefir, place the grains in fresh milk, cover tightly, and refrigerate.
Drink or refrigerate the milk kefir: The prepared milk kefir can be used or drunk immediately, or covered tightly and stored in the refrigerator for up to a week.
Activating Dried Kefir Grains: If you bought your kefir grains in a dried form, rehydrate them by soaking them in fresh milk at room temperature. Change the milk every 24 hours until the grains begin to culture the milk and make kefir. It may take 3 to 7 days for the kefir grains to become fully active.
What Milk to Use: Kefir works best with whole-fat cow, goat, sheep, or other animal milk. You can use low-fat milks, but refresh the grains in whole fat milk if they stop fermenting the kefir properly. Raw and pasteurized milks can be used, but avoid ultra-high temperature (UHT) pasteurized milks.
Making More or Less Kefir: You'll need about a teaspoon of grains to ferment 1 to 2 cups of milk. You can also ferment less milk than this, but fermentation will go more quickly. Your grains will start to multiply over time, allowing you to ferment more milk if you like. Maintain a ratio of about a teaspoon of grains to 1 cup of milk.
Taking a Break from Making Kefir: To take a break from making kefir, transfer the grains into a fresh container of milk, cover tightly, and refrigerate for up to a month.
What to Do if Your Kefir Separates: Sometimes kefir will separate into a solid layer and milky layer if left too long. This is fine! Shake the jar or whisk the kefir to recombine and carry on. If this happens regularly, start checking your kefir sooner.