Pasteurisation is a heat treatment in which the milk is heated to 72 ºC for a few seconds to reduce bacteria and other microorganisms that can spoil the cheese during processing, or make it unsafe for consumption. There are varieties of cheese made exclusively with raw milk, and during their manufacture they are not subjected to any thermal or physical process to eliminate bacteria. In this case, the microorganisms present in the milk remain unaltered and are passed on to the cheese, which requires exhaustive controls on hygiene and the production process.