The principle of the two electrodialysis configurations used is the extraction of citrate anions from the juice and their replacement by hydroxyl ions provided either by the NaOH solution in the C2 compartment (ED3C,Fig. 1) or by the bipolar membrane sandwiched between the juice and electrode compartments (EDBM2C, Fig. 2). In the latter configuration, citric acid was formed in the C1 compartment by citrate ions extracted from the juice and protons provided by the second bipolar membrane separating the C1 and electrode compartments.