Pasteurization

Pasteurization (also pasteurisation) is a method of food preservation that reduces harmful microorganisms and organisms responsible for spoilage. Traditional pasteurization uses controlled heating. It differs from sterilization because it does not eliminate every microorganism. The term has also been extended to treatments using other mechanisms, including high-pressure processing.

History

The process takes its name from Louis Pasteur, whose nineteenth-century investigations connected spoilage with microorganisms and explained why heating could preserve a product. Heating as a preservation technique predated his explanation. In 1886, the agricultural chemist Franz von Soxhlet proposed applying pasteurization to bottled milk.

Adoption in urban milk supplies involved disputes over cost, flavour and the relationship between heat treatment and hygiene. Advocates of cleaner farms and distribution systems questioned whether heating addressed the underlying conditions of production. Pasteurization subsequently became part of the wider modernisation of milk handling, rather than a replacement for cleanliness.

Process design

A process must account for the food being treated, the microorganisms of concern, the equipment and the intended storage conditions. A treatment suitable for one product cannot simply be assumed to work for another. Heating affects food quality as well as microbial survival, so process design also considers unwanted changes to the product.

Milk is a familiar application. Heating and holding time work together: examples described in the scientific literature include short treatment at a higher temperature and longer treatment at a lower temperature. Pasteurized milk and milk processed at ultra-high temperatures are distinct products; packaging and subsequent handling also affect their storage requirements.

Other foods and storage

Pasteurization also forms part of the processing of vegetables and ready-to-eat meals. Heating can change their colour, texture and nutritional components. Storage conditions remain important after treatment: refrigeration slows microbial growth and chemical deterioration, while acidity, formulation and packaging also influence how long a product keeps. Shelf life therefore depends on the particular food and its handling.

Checking heat treatment

Changes in milk components can indicate the extent of heating. Alkaline phosphatase, an enzyme naturally present in raw milk, is inactivated by pasteurization and is used as an indicator of treatment effectiveness. Other analytical approaches examine whey proteins and compounds formed during heating. These methods assess different consequences of the heat treatment rather than measuring a single interchangeable property.

Attribution

Attributed adaptation of English Wikipedia's Pasteurization, revision 1366228867, consulted 14 October 2026. Contributor history. Prose rewritten and scope condensed using the cited secondary sources. CC BY-SA 4.0.