If you read the recipes, making yogurt sounds complicated, but in fact, all you have to do is combine milk with a starter culture and keep it warm. Then, you cool the mixture in the refrigerator and there it is: Homemade yogurt!
We made yogurt at my house this weekend following a very simple recipe. Here's how it works:
1. Start with milk.(We used a quart of organic milk.)
Yogurt is a fermented food thought to have originated in Turkey. For centuries, people have made yogurt as a simple food preservation technique. Yogurt contains bacteria that produce lactic acid, which helps prevent milk from spoiling, makes it thicker and produces the tangy taste.
Yogurt from cow's milk is what most of us in the United States are used to, but in other parts of the world it's often made with goat or sheep milk. The nice thing about making your own yogurt is that you have complete control over what you use: goat's milk, skim milk, organic milk or even raw milk. It's entirely up to you.
2.Control the Heat.(We put the milk in a pot on the stove, and used a candy thermometer to monitor the temperature.)
The idea is to bring the temperature of the milk to just below boiling (about 200 degrees F) and keep it there for about 10 minutes. This kills any undesirable bacteria in the milk, and helps it thicken. After it's been cooking for 10 minutes, you need to cool the milk to about 120 degrees F. We put our pot of milk in a pan of cold water, using the candy thermometer to watch the temperature.
This is just one way to do it. Many yogurt recipes recommend using a double boiler instead of a regular pot. You can also buy a yogurt maker, which sounds like a simpler way to get the temperature right. Yogurt makers range in cost from about $15 to $50.
3. Add the Bacteria. (We used one-quarter cup of plain yogurt.)
Now you need to add the starter culture, which has the bacteria that turns the milk into yogurt. That sounds hard to find, but it's not. All you need is a little plain yogurt. Who knew? Yogurt creates more yogurt.
You'll need to choose a brand with live cultures. (If you're not sure check the label.) The specific bacteria that make yogurt are Lactobacillus bulgaricus and Streptococcus thermophilus.
4. Keep it Warm. (We put the warm mixture into a thermos to let it incubate.)
Now you can sit back and let the bacteria work. The tricky part is that the bacteria work best within a narrow range of temperatures ? it has to be between 100 and 130 degrees F ? so you need to find a way to maintain a temperature of about 115 degrees F for at least four hours. Again, a yogurt maker might be handy because it would allow you to set the temperature, but there are numerous other methods people use to produce the right temperature.
Some recipes suggest putting the yogurt in the oven with the light on, or putting the yogurt in an insulated cooler. We decided to try a very simple method: Putting the yogurt in a thermos. We let it sit overnight, and then refrigerated it. Success! It tasted just like store-bought yogurt.
5. Refine your Technique. (It's time to make more yogurt!)
Although making yogurt is a pretty simple process, there's a lot of room for experimentation. You can add flavorings, such as sugar or vanilla; or thickeners, such as powdered milk or gelatin. If you let it incubate longer, the flavor gets tangier.
Ready to try some yogurt on your own? Try these sites for yogurt-making tips, techniques and troubleshooting. We'd also like to hear your tips for making yogurt. You can post them in our comments section.
University of Missouri Extension
National Center for Food Preservation
Megan E. Phelps is a freelance writer based in Kansas. She enjoys reading and writing about all things related to sustainable living including homesteading skills, green building and renewable energy. You can find her on Google+.