Ultra-high temperature processing (UHT), ultra-heat treatment, or ultra-pasteurization 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.
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 packaged in a sterile container, 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.
The pasteurized milk process is as follows:
Acceptance of raw milk → filtration, purification → standardization → homogenization → sterilization → cooling → filling → inspection → refrigeration
Application of Plate Heat Exchanger in Ice Cream Production
Plate heat exchanger is widely used in the food industry, with ice cream as the representative product. The production of ice cream mainly includes steps such as the mixing of the mixture of sterilizing and cooling, the filling and packing of ice cream. Before into the homogenizer, ice cream mixed material needs to be strictly controlled between 65℃ ~ 70℃ through the plate heat exchanger. When the temperature is too low, fat is easy to be condensed; when too high, material is prone to have hot stink. And then before into the aging tank, use the plate heat exchanger for sterilization, and make the material temperature up to the aging of the required temperature. Make heating and sterilization done at the same time to save cost. Ice cream material is relatively viscous, Hofmann’s BNF series of plate heat exchanger with wide flow path, and high heat transfer efficiency, can be a good choice for this heat transfer work.