I first learned to make homemade yogurt when reading The Tightwad Gazette, (see my side bar at the spinning carousel), long before I had children. I had it perfected by the time my son came along, which was a good thing because that boy can eat some serious yogurt!
Here are the steps:
1. Pour milk into a quart jar. (I use an old canning jar.) If you are making this for your baby, choose whole or 2% milk.
2. Heat slowly on the stove. Use a candy thermometer. Stir frequently in the beginning and continuously once the thermometer reaches 150 degrees. Continue to stir continuously and cook until the milk reaches 180 degrees. Remove from heat once it reaches 180 degrees.
3. Meanwhile, have two tbsps. of yogurt sitting out, warming to room temperature while the milk is cooking. I tend to buy a large container of yogurt and freeze it in ice cube trays, each ice cube formation holding 1 tbsp. of yogurt. Take 2 out and let them unthaw in the refrigerator the night before and then on the stove when you start to cook the milk.
4. After the milk has reached 180 degrees and you have removed it from heat, add some of the cooked milk to the yogurt and stir. Then, add the yogurt starter mixed with some of the milk to the pot of milk. If you would like to sweeten it, add some honey. (Do NOT do this if you are making yogurt for baby.) Some people like to add plain gelatin to the milk to make the yogurt thicker. I don’t usually do this, and I would recommend NOT doing it for baby.
5. Let the milk/yogurt mixture cool to 115 degrees. I know that it takes about 30 minutes for mine to cool to that temperature, so I set the timer and do other things around the house while waiting.
6. When the milk/yogurt reaches 115 degrees, transfer it back to the canning jar and put on a plastic lid. I then wrap it in a heating pad. (Our heating pad is very old, so I put it on the highest setting 75 degrees. You may put yours on a lower temperature if it functions properly, unlike mine.)
7. I then wrap it all in a towel to retain the heat and let it sit on the counter incubating for 8 to 10 hours.
Ruth Yaron in Super Baby Food recommends feeding your baby one yogurt meal a day (if the baby is six months or older) mixed with fresh, pureed fruits or vegetables. I just started my baby on yogurt yesterday.