The primary way to make sure of the safety of milk was through pasteurization, a process Pasteur invented in the 1860s, although not used to purify milk until 1890sm when Sheffield Farms Dairy – later part of Sealtest/Kraft – installed the first pasteurizer in a New Jersey plant. Many of the larger dairy companies therefore were already pasteurizing their milk by the time the city passed its pasteurization requirements.
The first commercial pasteurization machines came on-line in the mid-1890s and remained the standard for decades. Recently, ultra-high temperature pasteurization, commercially available since 1948, has become more common due to the increased shelf-life and total sterilization it gives milk.
- Dupuis, in E. Melanie. Nature’s Perfect Food: How Milk Became America’s Drink. New York and London: New York University Press, 2002.