UHT is a heat treatment at an ultra-high temperature, where the milk is exposed to heat, at a temperature of at least 135 °C, for a short time. Then it is cooled to room temperature and packaged aseptically (germfree). It is a popular product because it has a long shelf-life without refrigeration and is consumable in diverse ways. It is commercialized with various fat content and flavors, and using modern technology, some of the UHT products are also available in lactose-free form.