While they both have a creamy texture and a sour taste, kefir and buttermilk are very different foods. Buttermilk is made only from cow's milk and traditionally it is the product leftover from making butter. Kefir is made from a variety of different milks, and is deliberately soured to introduce healthy microorganisms to the food. Buttermilk is traditionally used for baking, while kefir is drunk as a refreshing beverage.
Kefir Is Produced by Adding Grains
Kefir can be made from any type of milk, including cow's milk. However, other milks, such as goat or sheep's milk, can also be used, as can fruit and grain milks, such as coconut, soy and rice milks. Kefir is produced by adding grains, called kefir grains. These white or yellow, cauliflower-shaped clumps contain healthy bacteria and yeast. When exposed to milk, it ferments the milk, thickening and souring it.
Buttermilk Originated as Byproduct
Old fashioned buttermilk is the byproduct produced from churning cream to make butter. However, the buttermilk available in grocery stores is very different — it is made by culturing low-fat or nonfat milk. Cultured buttermilk is very sour and thick, and, unlike traditional buttermilk, is rarely consumed on its own. Instead, it is used in baked goods, where it adds flavor and functions as a leavening agent. Cultured buttermilk is made by introducing bacteria, similar to that used in yogurt, to milk. Commercially made buttermilk, such as that found in grocery stores, often also contains additives such as carrageenan to give it a thick texture.
Make Buttermilk at Home
To make buttermilk at home, add a small amount of leftover commercial buttermilk to low-fat or nonfat milk. You can also use full-fat milk, but this is less common. Use a 1 to 16 ratio of buttermilk to milk. Let the mix sit, covered with a clean cloth or coffee filter, but not sealed, at room temperature for 10 to 24 hours. When the milk moves away in a single block from the edge of the jar, seal and refrigerate it. It is ready to be used after 6 hours in the fridge and once it has been stirred.
Make Kefir at Home
Kefir can be made at home by adding kefir grains to milk. Use 1 teaspoon of grains per cup of milk, mix and store in a clean glass jar, covered with a napkin or cheesecloth, but not sealed. Leave the jar at room temperature for 12 to 48 hours. The kefir is ready when the milk has thickened slightly and is tangy tasting. Strain your kefir to remove the grains, adding it to fresh milk for a second batch. Store leftover kefir -- it can be consumed as soon as it has been strained -- for no longer than one week. Purchase kefir grains online or at a Middle Eastern grocer. They can also be found in some health food stores. After awhile, the grains will begin to multiply, and you can also share them among friends.
Use Buttermilk, Kefir for Baking, Drinking
Both kefir and buttermilk have many uses in addition to being used for baking or consumed as a beverage. The natural creaminess and sour taste of the two liquids means they make an excellent, low-fat base for salad dressings. Add in olive oil, seasonings and either kefir or buttermilk, shaking vigorously to combine the flavors. You can also use them as bases for an ice cream or even flavored frozen treats. Puree fresh fruit and sugar with buttermilk or kefir, pour into plastic molds and freeze. They can also be used in place of yogurt for smoothies and soups.