Electrostatic Interactions of Ion-Exchange Materials with Anthocyanins in the Processes of Their Sorption and Electrodialysis Extraction from Liquid Media

The nutritional value of wines as well as fruit and berry juices is to a large extent determined by the presence of anthocyanins in them, which possess antioxidant activity. To extract these substances from food waste as well as to condition juices and wines, ion-exchange resins and membranes based on them are being increasingly used. The kinetics of sorption of anthocyanins by ion-exchange resins from model solutions with pH of 3, 6, and 9 is studied. It is shown that the Donnan exclusion of coions leads to a change in the structure of anthocyanins in the internal solution of ion-exchange materials compared to the external solution. As a result, the electrostatic interactions of anthocyanins with ion-exchange materials are weakened or enhanced compared to the expected interactions based on pH of the external solution. Large anthocyanin molecules more easily penetrate heterogeneous ion-exchange membranes compared to the resins from which they are fabricated. The reason is the presence of extended macropores localized at the boundaries of the contacts of the reinforcing cloth and composite of the ion-exchange material with an inert binding agent in the membranes.