Waste water from citrus processing as a source of hesperidin by concentration on styrene-divinylbenzene resin

This paper describes a procedure for recovering hesperidin from the waste w ater of orange juice processing, namely, yellow water, by concentration of diluted extracts on styrene-divinylbenzene resin. Turbid raw material flowi ng out from centrifuges of essential oil separation contains considerable a mount of hesperidin (similar to 1 g/L) mainly associated with solid particl es. Yellow water was treated with calcium hydroxide until pH 12 to solubili ze hesperidin, filtered, neutralized at pH 6, and loaded on resin up to sat uration. Desorption with 10% ethanol aqueous solutions at different NaOH co ncentrations (0.23-0.92 M) assured high concentration of hesperidin in sele cted fractions (10-78 g/L), from which it precipitated in high yield and pu rity immediately after acidification at pH 5. Best results were obtained us ing 0.46 M NaOH as eluent: 71.5% of the adsorbed hesperidin was desorbed in 300 mt, with an overall 64% yield of isolated product at 95.4% purity (HPL C). These experiments can constitute a useful starting point for an industr ial application.