Red plum juice was clarified by membrane processing by analyzing several parameters, including pore size, transmembrane pressure (TMP), feed flow rate, temperature, and membrane type, to optimize the performance of the membrane permeate flux and the quality of the clarified juice. Membrane clarification did not have a significant effect on pH, while total phenol content, anthocyanin, antioxidant activity, acidity, total soluble solid content, and turbidity decreased remarkably (about 99% rejection). The analytical results demonstrated that there was no significant difference by examining the permeate flux obtained using various pore sizes. Also, the highest steady-state flux (3.4 kg m−2 s−1) occurred when the process was operated at 1.3 bar TMP. Moreover, increasing the velocity from 0.2 to 0.5 m s−1 and temperature from 20 to 40°C decreased the total fouling resistance by about 45 and 50%, respectively. Finally, based on the results, the mixed cellulose ester membrane with a pore size of 0.1 μm, a TMP of 1.3 bar, a velocity of 0.5 m s−1, and a temperature of 40°C was selected as the most suitable membrane and operating conditions for clarification of red plum juice.
