Ultra-high-temperature processing

Ultra-high temperature processing (UHT), or ultra-heat treatment, sterilizes food by heating it above 135 °C (275 °F) – the temperature required to kill spores in milk – for 1 to 2 seconds. UHT is most commonly used in milk production, but the process is also used for fruit juices, cream, soy milk, yogurt, wine, soups, honey, and stews. UHT milk was first developed in the 1960s and became generally available for consumption in the 1970s.

The heat used during the UHT process can cause Maillard browning and change the taste and smell of dairy products. An alternative process is HTST pasteurization (high temperature/short time), in which the milk is heated to 72 °C (162 °F) for at least 15 seconds.

UHT milk, if not opened, has a typical unrefrigerated shelf life of six to nine months. HTST pasteurized milk has a shelf life of about two weeks from processing, or about one week from being put on sale.

Nutrition