Background
Cheese is a fermented food derived from the milk of various mammals. Since humans began to domesticate milk-producing animals around 10,000 B.C. , they have known about the propensity of milk to separate into curds and whey. As milk sours, it breaks down into curds, lumps of phosphoprotein, and whey, a watery, grey fluid that contains lactose, minerals, vitamins, and traces of fat. It is the curds that are used to make cheese.
The first cheeses were "fresh," that is, not fermented. They consisted solely of salted white curds drained of whey, similar to today's cottage cheese. The next step was to develop ways of accelerating the natural separation process.
Most cheese is made from pasteurized milk today. Pasteurization entails heating milk to partially sterilize it without altering its basic chemical structure.
The first and simplest way of extending the length cheese would keep without spoiling was simply ageing it. Aged cheese was popular from the start because it kept well for domestic use. They developed a method of grinding old cheese, adding filler ingredients, and heating the mixture to produce a sterile, uniform, long-lasting product.
However, with the advent of mass production, both the supply of and the demand for cheese have increased. most cheeses are produced in large factories, a majority are still made using natural methods.