Application of osmotic membrane distillation process in red grape juice concentration

The osmotic membrane distillation process was applied in dehydration of red grape juice (Most de Raïm Concentrat Negre) of different concentrations (5–20 °Brix). Experiments were performed using polytetrafluoroethylene (PTFE) hydrophobic membranes of different nominal pore diameter. Red grape juice solution and concentrated calcium chloride solution (50 wt.%) were used as feed and stripping solutions, respectively. The permeate flux, the initial and the final juice concentration, the total phenolic content (TPC) and the antioxidant activity (TEAC) were measured for each single experiment.It was found that the final juice concentration was proportional to the time of the OMD dehydration process and the initial juice concentration. Results showed that during the concentration of juices by the OMD dehydration process the physicochemical properties like the total phenolic index and the antioxidant activity are well preserved.

► Osmotic membrane distillation was effectively used for the grape juice concentration.
► High permeate fluxes of water (5–7 kg m−2 h−1) were measured.
► Antioxidant properties of grape juice were preserved during the OMD process.