1 gallon milk
1 T unflavored gelatin (I use beef gelatin)
1 c plain unflavored yogurt
**Before using a candy thermometer, whisk, or other utensil in the warm yogurt, sterilize them in boiling water first.**
Pour the gallon of cold milk into a crock pot. Sprinkle with gelatin and let soften for 5 minutes. Whisk the gelatin into the milk, put the lid on the crock pot, and turn on to low for 3 hours. At the end of 3 hours, check the temperature of the milk with a candy thermometer. It should be at 170 degrees. If not, put the lid back on and keep checking until it is. Make a note as to how long it takes to get to 170 on your crock pot. Then turn the crock off and let it sit for 3 hours. (When the heat is turned off the crock pot, take the 1 c yogurt, which is your starter, out of the refrigerator and let it come to room temperature.) At the end of 3 hours, check the temperature of the milk with a candy thermometer. It should be between 100 and 115 degrees. (If not, continue to let it cool and make a note of how long it takes to get to 110.) When the milk is at 100, whisk the yogurt into the milk. Put the lid back on the crock pot, and wrap the unplugged crock in a heavy bath towel, and let it sit undisturbed on your counter for 8-12 hours or overnight.
In the morning, remove the towel and the lid. You will have yogurt, but it will be thinner than we are used to. It isn’t finished yet. Whisk the yogurt so you will have a smooth consistency. Now place a colander (large enough to hold your gallon of yogurt) into a larger bowl. Line the colander with coffee filters or cheesecloth, and pour the yogurt from the crock into the colander. Cover the whole thing with plastic wrap and let it set in the refrigerator for 12 to 24 hours. The whey will slowly drain out of the yogurt into the bowl, and what is left in the colander will be yogurt! Spoon your yogurt into quart jars and store in the refrigerator. The whey tastes like thin buttermilk and makes good bread, biscuits, pancakes, or cakes – any baked good that calls for milk or water for the liquid.
I use my homemade yogurt in smoothies. Flavored yogurt can be made the same way with fresh fruit instead of frozen.
Be sure to save 1 c of your homemade yogurt plain and unflavored, to use as starter for the next batch.
While there is a cost savings, it is not really that high when you factor in the time involved. The main advantage to homemade yogurt is knowing that the gelatin in your yogurt is from a non-pork source, and also of course, being able to control the level and type of sugar and the quality of the fruit in the finished product.
Many thanks to A Year of Slow Cooking for the initial crock pot yogurt recipe, which I modified slightly here.