Ultra-high temperature processing, ultra-heat treatment (both abbreviated UHT), or ultra-pasteurization is the sterilisation of food by heating it for an extremely short period, around 1–2 seconds, at a temperature exceeding 135°C (275°F), which is the temperature required to kill spores in milk. The most common UHT product is milk, but the process is also used for fruit juices, cream, soy milk, yogurt, wine, soups, honey, and stews.

A process using equipment disinfected before use, and which, in running conditions, is protected against recontamination by micro-organisms that may harm the safety and suitability of the specific product that is made. Measures for initial reduction of microbial load and against recontamination can be less stringent than those applied for an aseptic process. Ultra clean or Aseptic refers more to the process line and not the environment.

A pipe coupling.

Length of time a diluted product can remain active and effective. Stability of the chemical as well as the storage conditions determine the use-life of antimicrobial products.