Enrichment and fractionation of major apple flavonoids, phenolic acids and dihydrochalcones using anion exchange resins

In the present study model solutions containing isolated apple polyphenols were employed to systematically study their interaction with two strong anion exchangers differing in the structure of their polymeric matrix. Equimolar concentrations of catechin, caffeic acid, 5-O-caffeoylquinic acid (chlorogenic acid), phloridzin and rutin were used in single compound, binary, ternary, quaternary and pentenary model systems to investigate their ion exchange and adsorption behavior when brought into contact with a polystyrene divinylbenzene-based and a polyacrylamide-based ion exchanger resin in a column system. To enhance differentiation between adsorption phenomena involving the lipophilic backbone of the exchanger resin and ion exchange processes, experiments were performed at pH 1 and 7. The results of this study allow a deeper insight into the complex processes occurring upon ion exchange. Significant differences were found using the two ion exchangers with the polystyrene resin showing higher recovery rates indicating that the polymeric backbone also markedly contributes to polyphenol binding through hydrophobic interactions. Furthermore, resin selectivity with regard to the binding of phenolic compounds was also shown to be dependent on the structure of the exchanger matrix. These results may further contribute to improve industrial processes for the cost-efficient and selective recovery of secondary plant metabolites, thus allowing to systematically manipulate the biofunctional properties of plant extracts. (C) 2010 Elsevier Ltd. All rights reserved.