Optimization of polyphenol recovery from mango peel extracts by assessing food-grade adsorbent and ion exchange resins and adsorption parameters using a D-optimal design

Abstract

Seven adsorbent and anion exchange resins with different polymeric backbones and functional groups were evaluated in the present study regarding their polyphenol adsorption efficiency. A food-grade strong basic anion exchange resin proved to be most suitable for gallic acid adsorption from a model solution, presumably due to its cross-linked polystyrene matrix and functional quaternary ammonium groups. Besides gallic acid, the nonionic mangiferin was efficiently adsorbed by this resin. Optimum conditions for gallic acid binding were identified by means of a D-optimal design at the independent process parameters of pH 7, temperature of 293 K, 50 mg/L gallic acid concentration, and 0.12 g DM resin per 100 mL gallic acid model solution. Optimum adsorption conditions were transferred from batch experiments to column adsorption experiments using a complex phenolic mango peel extract. Polyphenol binding from the crude peel extract was excellent as demonstrated by an exhaustive adsorption of ≥99.9 % of differently structured polyphenols. Moreover, the desorption, i.e., recovery rate, of polyphenols was studied using both acidic and alkaline eluents. Polyphenol adsorption by anion exchange resins may contribute to optimized adsorption processes, thus, being useful for the industrial exploitation of sensory acceptable mango byproducts.