Purification and recovery of polyphenols from concentrated citrus wastewater by adsorption/desorption process

The citrus processing industry generates enormous amounts of wastes: solid residues from orange juice production process and mandarin wastewater from canned mandarin segments processing. These wastes are notably rich in high added-value bioactive compounds, such as polyphenols. Previous studies have explored extraction and concentration methods to recover and concentrate polyphenols from citrus waste. However, the high concentration of other compounds such as sugars and pectins in orange and mandarin concentrates, has prompted further studies on polyphenol purification using an adsorption/desorption process. The MN200 non-ionic resin was selected. First, different resin dosages were tested to recover polyphenols from model solutions simulating orange and mandarin wastewater. The best results were obtained with the resin concentration range of 20–30 g·L− 1. The equilibrium data fitted well the Temkin isotherm, while the adsorption kinetics were best described by the pseudo-second-order model. Secondly, polyphenol purification was performed from real mandarin and orange concentrate solutions. Polyphenols, sugars and pectin recoveries were 81.9%, 5.4% and 3.5%, respectively, for mandarin solution; and 64.5%, 3.6% and 2.9%, respectively, for orange solution, at a resin concentration of 20 g·L− 1. Hence, the solution obtained after the adsorption step could be used as a pectin concentrate with a great potential in the food industry. On the other hand, the solution obtained after desorption, enriched in polyphenols, could have a potential application in the pharmaceutical and cosmetic industries.