Pasteurization is a process of heating a food in order to kill bacteria and certain enzymes. This process is most often used in liquids like milk, juice, and beer in order to destroy yeasts, molds, and especially Mycobacterium tuberculosis, which causes tuberculosis. The process of pasteurization was created by Louis Pasteur and successfully tested on April 20, 1862.

Pasteurization is done on many food liquids to make it safer and increase its shelf-life. The most talked about pasteurized food is milk. There are two common methods for pasteurizing milk; high temperature, short time (HTST) and ultra-high temperature (UHT).

HTST is done by heating the milk to 72C (161.5F) for at least 15 seconds. This kills most of the unwanted bacteria, and doesn't harm the useful proteins or effect the taste of the milk. Most milk bought at the grocery store is pasteurized in this manner.

UHT pasteurization is done by heating the milk to 137.7C (280F) for at least two seconds. This kills even more bacteria increasing the shelf-life of the milk. Unfortunately, the high temperatures alter the taste of the milk by destroying some of the useful proteins and making it harder to digest.

No form of pasteurization kills all the bacteria in a food, because some bacteria is heat resistant and can survive extreme temperatures. The current methods of pasteurization may not be sufficient for milk and the FDA (Food and Drug Administration) is re-evaluating the methods.