History of Pasteurization

History

The process of heating or boiling milk for health benefits has been recognized since the early 1800s and was used to reduce milkborne illness and mortality in infants in the late 1800s. As society industrialized around the turn of the 20th century, increased milk production and distribution led to outbreaks of milkborne diseases. Common milkborne illnesses during that time were typhoid fever, scarlet fever, septic sore throat, diptheria, and diarrheal diseases. These illnesses were virtually eliminated with the commercial implementation of pasteurization, in combination with improved management practices on dairy farms. In 1938, milk products were the source of 25% of all food and waterborne illnesses that were traced to sources, but now they account for far less than 1% of all food and waterborne illnesses.
Pasteurization is the process of heating a liquid to below the boiling point to destroy microorganisms. It was developed by Louis Pasteur in 1864 to improve the keeping qualities of wine. Commercial pasteurization of milk began in the late 1800s in Europe and in the early 1900s in the United States. Pasteurization became mandatory for all milk sold within the city of Chicago in 1908, and in 1947 Michigan became the first state to require that all milk for sale within the state be pasteurized. In 1924 the U.S. Public Health Service developed the Standard Milk Ordinance to assist states with voluntary pasteurization programs. The Grade A Pasteurized Milk Ordinance (PMO), as it is now called, is administered by the U.S. Departments of Health and Human Services and Public Health, and the Food and Drug Administration and defines practices relating to milk parlor and processing plant design, milking practices, milk handling, sanitation, and standards for the pasteurization of Grade A milk products. Each state still regulates milk processing within their own state but dairy products must meet the regulations stated in the PMO for products that will enter interstate commerce.
Initial pasteurization conditions, known as flash pasteurization, were to heat the milk to 155 to 178°F (68.3 to 81°C) for an instant followed by cooling. Pasteurization conditions were adjusted to 143°F (61.7°C) for 30 minutes or 160°F (71.1°C) for 15 seconds to inactivate Mycobacterium bovis, the organism responsible for tuberculosis. However, in 1957 these conditions were shown to be inadequate for the inactivation of Coxiella burnetii which causes Q fever in humans (Enright et al., 1957). New pasteurization conditions of 145°F (62.8°C) for 30 minutes for a batch process, or 161°F (71.7°C) for 15 sec for a continuous process, were adopted in order to inactivate Coxiella burnetii, and these conditions are still in use today.