Fermented milk is regarded by many cultures as a delicious health food. It has cropped up all over the world in different forms: kefir from Caucasia, laban from the Middle East, dahi from India, creme fraiche from Western Europe, piima from Finland, mursik from Kenya, and yogurt from your grandmother's house. But these same people would scarcely recognize the colored, sweetened gel that passes for yogurt in grocery stores today.
Most if not all dairy-eating cultures ferment their milk. Why is this? There are three main reasons. First of all, unpasteurized milk spontaneously ferments at room temperature, usually becoming delicious "clabbered milk"- whereas pasteurized milk becomes putrid under the same conditions. So fermented milk is difficult to avoid. The second, related reason, is that fermentation prolongs the life of milk in the absence of refrigeration. Fully fermented milk is stable for weeks at room temperature.
The third reason is that these cultures know cultured milk is delicious and nutritious. Fermentation with specially selected cultures of lactic acid-producing bacteria and sometimes yeast work to break milk down into a form that is more easily assimilated. They partly (or fully) digest the lactose, which can be a problem for some people, turning it into tangy lactic acid. They also partially digest casein, a protein in milk that is difficult for some to digest. And finally, the lower pH of fermented milk makes its minerals more bioavailable.
Traditionally, milk was fermented in its unpasteurized state, but raw milk is hard to find in many industrialized countries. Raw milk has its complement of enzymes intact, such as lactase and lipase, which aid in its digestion. It also contains lactose-digesting bacteria that make milk easier for some to digest, and contribute to intestinal health. These are all eliminated by pasteurization. Fortunately, fermentation restores some of the benefits of raw milk. It reintroduces lactic-acid bacteria, along with their digestive enzymes. With that in mind, here's a simple yogurt recipe:
1/2 gallon whole, raw or pasteurized, cow or goat milk (add extra cream if you wish)
Starter culture (commercial starter or 2 tbsp of your favorite live-culture yogurt)
Glass jars with lids
Cooler or yogurt maker
1. Heat the milk to 110-115 F (43 C). If the temperature exceeds 115 F, let it cool.
2. Add the starter culture. If the starter is yogurt, whisk it into the milk.
3. Pour the milk into glass jars and keep it at about 110 F for 4-10 hours. 4 hours will yield a mild yogurt, 10 will be tangy. If you don't have a yogurt maker, this is the tricky part. You can use a cooler filled with 100 F water to maintain the temperature and spike it with hot water after a few hours, or you can ferment it in your oven with the pilot light on if the temperature is in the right range.
If you want a thicker yogurt, bring the milk to 180 F (82 C) and let it cool to 110 F before adding the starter. Add fruit, honey or other flavors before fermenting. Enjoy!
As a final note, I'll mention that milk simply does not agree with some people. If you've tried raw milk and homemade yogurt, and they cause intestinal discomfort or allergies, let them go.