Solvent swing adsorption for the recovery of polyphenols from black tea

Tea polyphenols are claimed to have many health benefits. The fact that tea is such a popular drink, together with all the potential health benefits, has led to an increased interest in the recovery and purification of the polyphenols. The most interesting groups of polyphenols present in black tea are the catechins and the theaflavins. To the best of the authors' knowledge, no report on a systematic resin screening study for the adsorption and desorption of specific polyphenols from black tea has been presented. Four food grade commercial macroporous resins are screened as a starting point for the characterization and optimization of a solvent swing adsorption process, to separate the polyphenols from black tea. It has been shown that the resin Amberlite XAD7HP has the best performance for the sorption of catechins, allowing the recovery of 60% of the catechins. The resin Amberlite FPX66 is the best for sorption of theaflavins, with a recovery rate of 59%. The adsorption process has been modeled with a Langmuir multicomponent isotherm. In desorption, a solution containing 70% ethanol (weight percent) in water is found to be the best desorption medium.