Kefir Basics

• Kefir grains are the traditional starting point for homemade kefir. They're called "grains" because of their granular appearance, though they contain no real grain. They're complex colonies of interrelated bacteria and yeasts, which quickly spring to life when they're placed in milk or similar liquids. They consume the natural sugars in the milk, producing small quantities of acidity, alcohol and carbon dioxide in the process. After a few hours the milk begins to thicken, eventually curdling and separating into curds and whey. The process can be stopped at any time by straining out the kefir grains and refrigerating the kefir. The grains are rinsed carefully and stored in the refrigerator for their next use.

Room-Temperature Kefir

• The appropriate length of time for aging kefir is entirely subjective. After 12 hours at room temperature, the milk should begin to thicken noticeably and develop a mildly pleasant tang. At this stage the kefir resembles buttermilk. If it's left for 24 hours, it will be distinctly sour and have a slight "fizz" on the tongue from natural carbonation. At 48 hours or longer, the kefir is very sour and separates completely into curds and whey. You can blend them back together for a sour, chunky beverage, or drain and compress the curds to make a kind of soft, fresh cheese. After five days, the kefir becomes alcoholic and the curds toughen, so it's seldom aged that long.

Refrigerator Kefir

• The microorganisms that turn milk into kefir work best at room temperature, but they can also make kefir in your refrigerator. It's much slower, taking 3 to 5 days to make ordinary kefir for drinking and even longer to make thick, chunky kefir. That's unfortunate if you're impatient and drink lots of kefir, but it can be a positive if you use less kefir and don't want to give it your attention every day. That's also how you store kefir grains for extended periods. If you just change the milk every week, you can keep your kefir grains dormant for 2 to 3 months. For longer-term storage, rinse the grains thoroughly in distilled water and dry them. Sealed in airtight bags in your refrigerator, they'll keep for up to 18 months.

Health Considerations

• Like natural yogurt, kefir is a potent natural source of probiotic bacteria, which can help ease many digestive complaints. A 2004 Japanese study also demonstrated that it might be useful in controlling blood pressure, blood glucose and serum cholesterol. If you don't drink dairy milk because of allergies or ethical concerns, kefir grains can be used instead with most milk substitutes, including soy and nut milks, as well as fruit juices or even water. The nutritional profile of the kefir varies with the base beverage used, but the health benefits are largely consistent from one to another.