4 cups milk, whole or low fat
1/2 cup plain yogurt
1 cup instant nonfat dry milk
Heat regular milk to 180 degrees F, using a candy thermometer. When the milk has reached the correct temperature, remove it from the heat and stir in the dry milk. Cool milk to between 105 degrees F and 110 degrees F and stir in the plain yogurt. Pour the mixture into sterilized glass jar. Incubate yogurt for 4 to 8 hours by using one of the following methods. Depending on the method used, check a few times during the incubation period to see if the mixture has reached the consistency of custard. When it has, the yogurt is ready to refrigerate. Yogurt will keep for 2 to 4 weeks in the refrigerator.
To flavor yogurt, add a teaspoon of honey or a tablespoon of fruit preserves.You can also add cinnamon and any other spices and flavors that you like.
Pour yogurt into containers that come with your commercial yogurt maker and follow the manufacturer's instructions.
Place jars and a thermometer in an insulated picnic cooler. Cover carefully with a towel, and close the cooler. Check only once or twice, and add a jar of warm water if the temperature goes down.
Place the jars, covered with a towel, in a 100 degrees F oven.
Place the jars, covered, on a rack in an electric frying pan. Pour in an inch or two of warm water, set the thermostat to 100 degrees F and cover the pan.