Cheese cultures are necessary to inoculate the milk with friendly bacteria. These bacteria serve two functions. First, they cause the milk to become more acidic aiding its coagulation. Second, the bacteria help develop the flavor of the cheese. . Cheese cultures are divided into two basic types mesophilic and thermophilic. These terms describes at the temperature the culture thrives at. Mesophilic (from the Greek words meso - meaning intermediate and philic - which means loving) cultures thrive around room temperatures. Thermophilic (from the Greek words thermo - meaning heat and philic - which means loving)cultures require a higher temperature.
Thermophilic will set up to two gallons of milk for making a variety of cheeses including Mozzarella, Parmesan, Romano, Swiss and many more.