Ultra-High-Temperature Processing

Ultra-high-temperature processing, also called ultra-heat treatment or ultra-pasteurization, sterilizes liquid food by heating it above 140 degrees Celsius for two to five seconds, destroying bacterial endospores that survive ordinary pasteurization. It is used mainly on milk but also on fruit juice, cream, soy milk, yogurt, wine, soup, honey and stew; UHT milk emerged in the 1960s and reached commercial markets in the 1970s. Milk treated this way and packaged in sterile containers keeps for six to nine months without refrigeration, far longer than flash-pasteurized milk, which is heated to 72 degrees Celsius for at least fifteen seconds, needs refrigeration and typically lasts only about two weeks after processing; UHT's more intense heat can also trigger Maillard browning that changes the taste and aroma of dairy products.