IMPROVEMENTS IN OR RELATING TO PROCESSES OF TREATING EMULSIONS AND SUSPENSIONS

1,220,211. Drying processes. R. A. P. WERTHEIM. 3 Jan., 1968 [3 Oct., 1966; 11 Oct., 1966; 28 Feb., 1967], Nos. 44093/66, 31091/66 and 9434/67. Heading F4G. Emulsions or suspensions of fat and water or mixtures containing coagulizable components in suspension or solution are dried by a process comprising the steps of (a) first cooling the mixture at a temperature sufficiently low to cause at least part of the water in the mixture to freeze followed further cooling at the same or at a lower temperature (b) raising the temperature of the mixture to thaw the mixture (c) removing at least part of the water and (d) dehydrating the resultant residue. The freezing may be effected, after an initial pre-cooling, by cold storage or a blast of cold air. The thawing may be effected by warm air or steam or H.F. or radiation heating. The mixture may be covered by a polyethylene terephthalate film during freezing and thawing. After thawing the water may be removed by centrifuging, straining or filtering. The dehydration may be effected by freeze-drying or by absorption of water into a desiccant e.g. an alumino-silicate, under a reduced pressure. Preferably the mixture is "sandwiched" between desiccant layers, being separated therefrom by moisture-permeable barriers. The mixture, which may be real or imitation cream, milk or yoghurt, may be pasturized before, between or after the freezing steps, and the dehydrated product may be suitably disintegrated.