The demand for fruit juices with high quality rather than the whole fruits has been increasing day by day. However, transportation and storage of fruit juices is uneconomical and unsuitable as it subjects to rapid spoilage. Concentration of liquid foods in general and fruit juices in particular to high concentration up to 70-80% removes a significant amount of water. Hence it causes a significant reduction in transport, packing and storage cost with much greater stability of the concentrates. Recently, many modern techniques have been used for juice concentration in food industry. They include evaporative concentration, reverse osmosis and freeze concentration. However, these techniques suffer several disadvantages and in one way or another do not fully satisfy the standards set by manufacturers and the customers. Another novel technique, called Osmotic Membrane Distillation (OMD), has become of increasing interest to many researches and food scientists as a competitive alternative to other concentration techniques as it give high quality and concentrated product juice [1, 2].

      The current research work focusses the theoretical investigation of dehydration of clarified fruit juices through a laboratory scale hollow fiber membrane contactor. OMD works on the transfer of water molecules from fruit juices from one side of a polymeric membrane to other side of the membrane where osmotic agent was kept in contact. Aqueous solution of calcium chloride (CaCl₂) was taken as osmotic agent and sucrose solution of 10 – 12 ⁰Brix was treated as model solution for fruit juices. Activity difference between the two solutions causes a difference in vapour pressure gradient which consequently causes the evaporation and condensation of water molecules across the membrane where the model sucrose solution and brine is flowing, respectively. The membrane used was hydrophobic thus avoided from wetting it. Theoretical mass transfer model is developed where negligible heat transfer effects are assumed during the transfer of water molecules across the membrane. Resistance-in-series model is adopted and water transport flux estimation is developed in hollow fiber membrane contactor. Feed (sucrose solution) and osmotic agent (CaCl₂) flow in either side of membrane. Knudsen flow was dominated because of the pore size of the membrane. The developed model was then simulated using MATLAB. The predicted water flux obtained from the simulation results was then validated with experimental results. Finally, the effect of different parameters on water transmembrane flux was studied.