Recovery of hesperidin from orange peel by concentration of extracts on styrene-divinylbenzene resin

This paper describes a new procedure for obtaining hesperidin from the wast e orange peel of the citrus industry. It is based on the adsorption of dilu te extracts of hesperidin on a styrene-divinylbenzene (SDVB) resin and the desorption in much more reduced volumes by means of alkaline eluents. Hespe ridin immediately precipitates with good yield and high purity after acidif ication of the concentrated solutions, thus overcoming disadvantages due to the high dilution. Different experiments were carried out to examine opera ting conditions in each phase of the process. Hesperidin was extracted from peel with an aqueous saturated Ca(OH)(2) solution, allowing precipitation of calcium pectates from colloidal pectins that can interfere in the subseq uent phases of adsorption and separation of hesperidin. The clear extracts were neutralized to optimize adsorption on resin. The most effective eluent was 0.5 N NaOH solution containing 10% ethanol. Recycling of the crystalli zation liquor improved the yield and purity of the product and reduced the acid amount required for neutralizing fresh alkaline extracts. Resin must b e washed after each adsorption-desorption cycle and regenerated after five cycles. Results can constitute a useful starting point for an industrial ap plication. A flow scheme of the process is also reported.