ABSTRACT
Membrane concentration processes have several advantages over conventional concentration processes, i.e., evaporation. Undesirable heat-related changes such as color, aroma, and viscosity characteristics are avoided because membrane processes can be operated at room temperature. Membrane processing in the food industry has been applied mainly for the clarification of fruit juices using microfiltration and ultrafiltration, and for concentration of fruit juices and dairy products. Membrane processes include a wide range of unit operations from sieving to reverse osmosis. The membrane structure varies in its chemical nature, microcrystalline structure, pore size and pore size distribution, and degree of asymmetry. The choice of membrane depends on the type of juice and the desired properties of the clarified juice. The membrane processes can be combined with ion exchange to deacidify fruit juices. Mass transport during pervaporation is achieved by partial vaporization through a nonporous selectively permeable membrane.
