To make tasty and healthy homemade yogurt, you need to use only fresh pasteurized milk. Pasteurization occurs at the factory: first, the milk is heated to 80 degrees, and then sharply cooled. This technique helps to kill pathogenic microbes and preserve all the beneficial properties as much as possible. Sourdough must be purchased from well-known companies in a pharmacy or supermarket in its original packaging. And most importantly, all utensils for preparing yogurt must be sterilized.