Effect of Ultra High Temperature Processing and Storage Conditions on Rates of Sedimentation and Fat Separation of Aseptically Packaged Milk

Rates of sedimentation and fat separation were determined for stored UHT treated milk. For each of three thermal treatments used for indirect and direct heating, homogenization pressures were 0, 10.34, or 20.68 MPa. Storage temperatures were 7, 22 and 35°C. Initial sediment deposits were greater for the direct system. Sedimentation increased with increased heat, treatment and/or storage temperature but decreased as homogenization pressure increased. The indirect system had higher activation energies for sedimentation for all homogenization pressures. Fat separation rates tended to increase with increased storage temperature. The direct system tended to produce more sediment and less fat separation than the indirect system for a given thermal treatment.