Orange juice concentration by osmotic evaporation and membrane distillation: A comparative study

In this work, the osmotic evaporation (OE) and membrane distillation (MD) processes were compared in terms of water flux and aroma retention. The concentration of a sucrose solution, used as a model fruit juice, was carried out in a hollow fibre membrane contactor. Although a similar overall driving force was used, the flux obtained using the MD process was less than half of that observed using the OE process, due to temperature polarization effects.The transport of citral and ethyl butyrate, two aroma compounds relevant in the orange juice aroma, was also compared for both processes. A higher retention of these compounds was observed with the OE process. From these studies, it could be concluded that, the OE process has advantages over the MD process, not only in terms of water flux, but also regarding the retention of aroma compounds.Finally, the concentration of a commercial orange juice by osmotic evaporation, was carried out. Due to the presence of suspended solids and macromolecules, a higher mass transfer resistance was observed.