I've been making homemade yogurt for over a year now, and was thrilled to discover how easy it really is.Our family goes through a lot of yogurt! This past summer, the kids and I were given a free sample of Greek style yogurt at the store. Oh boy! One look at the cost and I knew I had to come up with a way to make it at home.
I've tried different methods of yogurt making, but in the end making the yogurt in a crock-pot seems the easiest to me. One thing I did invest in was a digital food thermometer. The $10 cost was worth it to me, to be able to preset a target temperature and walk away until the signal beeps that the temp has been reached. I have a 7 qt crockpot, you may need to adjust the recipe to fit your own.
Crock-pot Greek Yogurt
12 cups skim milk
1 cup instant nonfat dry milk
2 tbsp vanilla (optional)
1/2-1 cup honey or sugar, depending on taste (optional)
1/2-1 cup nonfat plain yogurt*
Combine the skim milk and nonfat dry milk powder in crock-pot. Set digital thermometer to 180 degrees. Cover crockpot and turn on low. It usually takes 5 or 6 hours for the milk to reach 180 degrees. It's important to let it reach that temperature, as the heat will kill any bacteria that might interfere with turning it into yogurt.
When 180 degrees is reached, add the sweetener and flavoring, if desired. Leave the lid slightly ajar, and reset the thermometer to 120 degrees. Temperatures higher than this will kill off the good bacteria in the starter that make the yogurt.
When 120 degrees is reached (usually after 2 or 3 hours), add the nonfat plain yogurt. This is the starter. At this point I usually, turn the crockpot on low, with the lid off, while I stir the starter in very well. Only leave it on for a couple of minutes, as you don't want to raise the temperature too much. Turn off and unplug the crock-pot. Put the lid on tightly. Wrap the entire crock-pot warmly in towels or blankets. I use two, thick, beach towels. Leave it wrapped up for about 12 hours or overnight.
In the morning, unwrap the crock-pot. The contents will have turned into regular yogurt. You could stop at this point. If you want to make Greek Yogurt, there is another step.
Line a colander with four layers of cheesecloth. Put this into a large bowl. Carefully pour the liquid that is on top of the yogurt out. This liquid is whey, and can be used in other recipes. Pour the yogurt into the cheesecloth lined colander. Cover with plastic and set the entire bowl into the refrigerator.
Every so often, pull the colander out of the bowl, and pour off the whey. The yogurt will become thicker and thicker as the whey is drained out. I usually let it drain for at least four hours, sometimes longer.
Finally scoop the yogurt into a storage container and stir well. This recipe yields approximately 2&1/2 quarts of Greek yogurt.
*Some people save out yogurt from the batch, for starter from the next batch. It works, but I use fresh starter every time (unless I've run out). Starters can become contaminated with other bacteria over time, and cause the batch to fail
**If you have any yogurt making problems, see the links below for what I've tried.