Concentration of apple juice using direct contact membrane distillation

The direct contact membrane distillation process (DCMD) has been used to investigate the concentration of apple juice. Results show that at a constant temperature of juice in the hot cell, an increase in the flux permeates of DCMD resulted in reducing the temperature of cooling water in the cold cell. Increasing the temperature of juice in the hot cell reduces influence of the cooling water temperature in the cold cell on the flux permeate of DCMD. The influence of temperature polarization on the effectiveness of DCMD in apple juice concentration has also been detected. The dependence of flux permeates on operating temperature. The concentration of soluble substances in concentrate and hydrodynamic conditions in the experimental equipment has also been studied. In the concentration of apple juice, 50% of solids content was obtained when the permeate flux reached about 9 l/m2·h. Further concentration of juice to 60–65% solids resulted in reduced productivity (3.8–3.0 l/m²·h) and therefore a decrease in the biological value of the concentrate.