General Discussion

Milk is an excellent medium for microbial growth,[18] and when it is stored at ambient temperature, bacteria and other pathogens soon proliferate.[19] The US Centers for Disease Control (CDC) says improperly handled raw milk is responsible for nearly three times more hospitalizations than any other food-borne disease source, making it one of the world's most dangerous food products.[20][21] Diseases prevented by pasteurization can include tuberculosis, brucellosis, diphtheria, scarlet fever, and Q-fever; it also kills the harmful bacteria Salmonella, Listeria, Yersinia, Campylobacter, Staphylococcus aureus, and Escherichia coli O157:H7,[22][23] among others.

Prior to industrialization, dairy cows were kept in urban areas to limit the time between milk production and consumption, hence the risk of disease transmission via raw milk was reduced.[24] As urban densities increased and supply chains lengthened to the distance from country to city, raw milk (often days old) became recognized as a source of disease. For example, between 1912 and 1937, some 65,000 people died of tuberculosis contracted from consuming milk in England and Wales alone.[25] Because tuberculosis has a long incubation period in humans, it was difficult to link unpasteurized milk consumption with the disease.[26] In 1892, chemist Ernst Lederle experimentally inoculated milk from tuberculosis-diseased cows into guinea pigs, which caused them to develop the disease.[27] In 1910, Lederle, then in the role of Commissioner of Health, introduced mandatory pasteurization of milk in New York City.[27]

Developed countries adopted milk pasteurization to prevent such disease and loss of life, and as a result milk is now considered a safer food.[28] ... Pasteurization of milk was suggested by Franz von Soxhlet in 1886.[30] In the early 20th century, Milton Joseph Rosenau established the standards – i.e. low-temperature, slow heating at 60 °C (140 °F) for 20 minutes – for the pasteurization of milk[31][32] while at the United States Marine Hospital Service, notably in his publication of The Milk Question (1912).[33] States in the U.S. soon began enacting mandatory dairy pasteurization laws, with the first in 1947, and in 1973 the U.S. federal government required pasteurization of milk used in any interstate commerce.[34]

The shelf life of refrigerated pasteurized milk is greater than that of raw milk. For example, high-temperature, short-time (HTST) pasteurized milk typically has a refrigerated shelf life of two to three weeks, whereas ultra-pasteurized milk can last much longer, sometimes two to three months. When ultra-heat treatment (UHT) is combined with sterile handling and container technology (such as aseptic packaging), it can even be stored non-refrigerated for up to 9 months.[35]

According to the Centers for Disease Control, between 1998 and 2011, 79% of dairy-related disease outbreaks in the United States were due to raw milk or cheese products.[36] They report 148 outbreaks and 2,384 illnesses (with 284 requiring hospitalization), as well as two deaths due to raw milk or cheese products during the same time period.[36]

https://en.wikipedia.org/wiki/Pasteurization#Milk