Recovery of Anthocyanins from Pulp Wash of Pigmented Oranges by Concentration on Resins

A pulp wash (PW) coming from a plant for citrus processing of pigmented oranges was utilized as a starting material to recover anthocyanins, using the procedure of concentration on resin. Six commercial food-grade resins were tested to find the more suitable ones for adsorbing anthocyanins, and 96% ethanol was used as eluent for desorbing them. An automated experimental apparatus was developed to perform the adsorption−desorption procedure on column. The kinetics results in a batch system and experiments on column showed that the more efficient resins are those made of styrene−divinylbenzene having a pore radius ranging from 70 to 150 Å and a surface area from 600 to 800 m2/g, namely, Sepabeads SP 70 and Relite EXA 90. The richest fractions collected from these resins contained about 95% of the anthocyanins in a volume of about 2% of the loaded PW. The HPLC profile of the desorbed anthocyanins is the same as that in PW. These fractions contain other phenol compounds, such as hesperidin and derivatives of hydroxycinnamic acids, in remarkable amounts. Ethanol can be easily removed from the solution and recycled, thus affording a much more concentrated product which can find application as a food colorant or antioxidant ingredient for a nutritional integrator. Keywords: Anthocyanins; citrus byproducts; oranges; pulp wash; styrene−divinylbenzene resins