Fermented Dairy Products

There are three principal ways to make sour dairy products. One consists of warming or souring milk or cream, resulting in such products as crème fraîche, cream cheese, and cottage cheese. The second way is to add rennet to the milk to make fresh cheese, which can serve as the starting point for fermentation and aging of myriad other cheeses. The third method makes use of a variety of microorganisms, especially lactic acid bacteria and certain fungi, to ferment milk and convert the lactose to lactic acid and other substances. Products made this way include yogurt, kefir, Icelandic skyr, and the Middle Eastern labneh and doogh.