Abstract

The paper is devoted to the possibility of separating a concentrate of anthocyanin pigments from an aqueous extract (0.1% HCl) of grape pomace (Pinot noir) with the use of magnetic particles based on poly(vinyl alcohol) (M-PVA) having an average size of 1-3 microns. Due to their magnetic properties, these biologically inert, hydrophilic particles provide the possibility of fast and efficient separation from crude suspensions using an easily scalable magnet technology.

The application of magnetic separation technology allows carrying out the process of isolating anthocyanins within 25 minutes. The sorption capacity of M-PVA is 4-5 times higher compared to other non-ionic sorbents (Amberlite XAD 16, Stirosorb MCDS×100), widely used for the extraction of polyphenolic compounds.

In the developed process, the M-PVA particles adsorb up to 40-60% of the anthocyanins present in the initial solution. Afterwards, ethanol containing 0.1% HCl extracts 85% of the absorbed anthocyanins resulting in a purified and threefold concentrated solution if compared to the original extract. HPLC indicated that the pigment composition of the concentrate is the same as in the original extract. The efficiency of the magnetic particles does not decrease by the adsorption in turbid media and reuse is possible without special treatment.