Laboratory-Scale System to Process Ultrahigh-Temperature Milk .

A laboratory-scale, indirect, ultrahigh-temperature (UHT) system was constructed using stainless steel tubing (6.35 mm) as the barrier between the heating agent and the product. Nitrogen gas under 80 psi pressure propelled milk through the tubing of the system. The milk was preheated in a hot water bath, brought to sterilization temperature in an oil bath, and held at this temperature in a holding tube. After leaving the holding tube, the milk was cooled rapidly in an ice-water bath and aseptically collected in 250-ml amber colored glass bottles in a glove box. The system effectively sterilized milk with carefully controlled temperature and time.