Osmotic distillation product integrity

Osmotic distillation is unique among concentration processes in that feeds containing thermally labile or shear-sensitive components, and those with appreciable volatility, can be concentrated with little or no loss of product integrity. This characteristic is particularly important for the concentration of fruit juices and other liquid foodstuffs, such as vegetable juices, and tea and coffee extracts. These feeds contain a complex mixture of essential volatile hydrophilic flavor, and fragrance components in very low concentrations. Substantial depletion of these components by direct destruction or evaporation may render the product... 

Osmotic distillation is a relatively new membrane separation process, which is used primarily for the dewatering of liquid food products. The majority of reported applications have involved the production of fruit juice concentrates. The main advantage of OD over vacuum distillation, which is the conventional method for concentrate production, is the preservation of product integrity. Osmotic distillation is operated at mild temperatures (typically ambient), and thereby produces concentrates that are free from the effects of thermal degradation. Also, the delicate volatile flavor and fragrance components that are essential to consumer acceptance of fruit juice concentrates are largely retained. 

Scheme of an integrated membrane process for the production of concentrated fruit juices. UF = ultrafiltration RO = reverse osmosis OD = osmotic distillation. 

Membrane crystallizers, membrane emulsifiers, membrane strippers and scrubbers, membrane distillation systems, membrane extractors, etc. can be devised and integrated in the production lines together with the other existing membranes operations for advanced molecular separation, and chemical transformations conducted using selective membranes and membrane reactors, overcoming existing limits of the more traditional membrane processes (e.g., the osmotic effect of concentration by reverse osmosis). 

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