Pasteurization

Pasteurization exposes a food or beverage to a controlled temperature for a specified period to destroy or reduce pathogenic microorganisms and, in many products, organisms that contribute to spoilage. The required treatment depends on the food, the organisms of concern, and product characteristics. Pasteurization reduces risk but is not sterilization: some microorganisms or spores can survive, and safe handling and storage remain important.

The process is named after French scientist Louis Pasteur. In the 1860s, Pasteur demonstrated that heating wine and beer could prevent abnormal fermentation. The principle was later applied to milk and other foods. Milk pasteurization became an important public-health measure because untreated milk can carry pathogens, and widespread use helped reduce milk-borne illness.

Two common milk processes illustrate the time–temperature principle. In the low-temperature, long-time (LTLT) method, milk is heated to about 63 °C (145 °F) for 30 minutes. In high-temperature, short-time (HTST) treatment, it is heated to about 72 °C (161–162 °F) for 15 seconds. These are common examples, not universal prescriptions for every food or jurisdiction; applicable regulations specify treatments and operating requirements. Ultra-high-temperature (UHT) processing uses substantially higher temperatures for a few seconds and, when combined with aseptic packaging, can produce a shelf-stable product. UHT and ordinary pasteurization are related heat treatments but are not identical.

Pasteurization substantially lowers the risk from harmful germs that may be present in raw milk, including Salmonella, pathogenic Escherichia coli, Listeria, and Campylobacter. Public-health agencies advise choosing pasteurized milk and dairy products, particularly because foodborne infections can be severe for young children, older adults, pregnant people, and people with weakened immune systems. Pasteurized products still require appropriate refrigeration when directed on the label: heating does not prevent contamination after processing or stop all spoilage.

Pasteurization aims to reduce pathogens using temperatures generally below the boiling point of water and usually leaves a product with a shorter shelf life than a commercially sterilized product. Sterilization applies a more intensive process intended to destroy microorganisms and spores. The terms should not be used interchangeably. Product formulation, packaging, processing conditions, and storage together determine its practical shelf life.