Rance Miles leads several multimillion-dollar dairy companies in preparing milk and other products for distribution. Pasteurization, a process invented by Louis Pasteur in the 1860s that involves heating and cooling milk, is used to kill harmful bacteria and is required by law in the United States. All pasteurized milk undergoes this process where it is heated to between 161 and 191 degrees Fahrenheit before being rapidly cooled to prevent further bacterial growth before bottling.