Culture or starter
Use either starter made from a package of dry culture or start from a carton of fresh, plain yogurt from a good dairy.
Add milk according the amount of yogurt you wish to make.
Use pans for heating and pasteurizing milk, large pan for water-bath during incubation.
The containers for incubating yogurt can be glass cups, 1 pint and 1 quart jars, wide mouth thermos ( if it has an easy to clean liner and can be used only for yogurt - yeast can not be washed out and can interfere with yogurt or cheese making).
Use a Dairy Thermometer which can be purchased at a dairy supply or hardware store. If no thermometer is available one has to learn to tell pasteurization by watching as milk just comes to a boil. A skin starts to form and tiny bubbles appear. The water bath temperature for incubation is hotter than you can hold in your hand comfortably very long, but not hot enough to burn.
Use towels to cover pan and hold in heat if using hot water bath method.
Heat to pasteurization (140°) 1 quart whole milk plus 4 tablespoons powered milk to 4 tablespoons condensed milk. Cool to 115°. Add 1/4 cup starter. Stir well. Pour into containers and incubate 4 hours or until desired thickness in 115° water bath. Keep the dairy thermometer in the water bath. Water should come to the top of jars for even heat. Bottom heat should not be excessive. A rack might be useful. An electric warming tray sometimes holds water bath at an even temperature. An oven can used to maintain hot water temperature. Otherwise, add hot water, as necessary. A thermos bottle or yogurt maker can be used in place of the hot water bath. Do not stir or shake incubating yogurt; it will not "set" well (jell). Refrigerate.
Heat to pasteurization 1 quart milk. Cool to 115°. Add 1/4 cup starter and stir well. Pour in containers and incubate 4 hours or more at 115°. See procedure #1 above.
This yogurt must be made as soon as possible after milking to control bacteria. Use 1 quart fresh, clean, strained milk warm from the animal or strained, cooled and quickly warmed to 115° in jar in water bath. Add 1/4 starter, stir well and pour into containers and incubate at 115° 4 hours or more. Thermos bottles work very well for this unpasturized yogurt. Thermos should be preheated; incubate at room temperature for 12 hours then refrigerate. This yogurt may not be so successful as a starter for more yogurt making.
When incubation period is completed, drain thickened yogurt through cheese cloth or muslin until it is the consistency of cream cheese. Hang cloth or drain in colander 18-20 hours, turning and agitating some to get whey to drain out of center. When done, store in glass or suitable container and use as cream cheese. Yogurt cheese may be preserved longer than a week by making into small balls and packing in a wide-mouth jar and covering with olive or other good oil. Seal with a tight lid and refrigerate. Experiment with seasonings for use as a spread on bread or crackers. If cheese is to soft, roll balls in dry powdered milk, then put in jar and cover with oil. To make yogurt cheese, one needs to have at least 1 or 2 quarts to get quantity enough. The whey can be saved for adding to salad dressings and baking or soups where some sour addition adds flavor. May be added to blender health food drinks.
Hints In Yogurt Making
Use clean sterilized utensils. Lots of rinsing after cleaning agent is used as traces of detergents can destroy yogurt culture. Boil all jars and cheesecloth. Always keep 1/4 cup of your freshest and best plain yogurt for the next batch. Some flavorings can be added when making yogurt at the same time the culture or starter is added to milk. Increase starter by 2 tablespoons per pint of milk. The addition of fruits should be experimented with. Mild or tart flavor depends on time of incubation to refrigeration.