Pasturization Of Milk

French Scientist Louis Pasteur during the nineteenth century. Pasteur discovered that heating milk to a high temperature then swiftly cooling it before bottling it, enabled the milk to remain fresher for an extended period of time. Today the process of pasteurizaton is used widely in the drinks and foodindustry. This process slows spoilage caused by microbial growth.

Unlike sterilisation, pasteurization is not intended to kill all micro-organisms in the food. Instead, it aims to reduce the number of viable pathogens so they are unlikely to cause disease (assuming the pasteurized product is stored as indicated and is consumed before its expiration date). Commercial-scale sterilisation of food is not common because it adversely affects the taste and quality of the product. Certain foods, such as dairy products, may be superheated to ensure pathogenic microbes are destroyed.

http://en.wikipedia.org/wiki/Pasteurization