ABSTRACT
Addition or removal of heat to accomplish phase change is a necessary step in operations such as evaporation, crystallization and distillation. Evaporation of liquid is carried out in various processing industries. Evaporation differs from crystallization. Crystallization is a special case of evaporation where supersaturated solution is obtained by boiling off water or sovents to a large extent followed by separation of non-volatile solute as crystal on cooling. Heat supplied to the evaporator mostly comes from latent heats of condensation of saturated steam. Design of an evaporator is based on the mass and energy balance over the entire process. In food industries, different types of evaporators are used for concentration. The quality of the product ultimately depends on the heating time and temperature in the evaporator. Evaporation of liquid foods causes considerable loss of volatile aroma components. Several factors, such as viscosity, solubility, scale depositions, formation of foam and materials of construction, affect the operation and performance of food evaporators.
