Influence of Membranes Characteristics On Anthocyanins Enrichment of Cranberry Juice by Electrodialysis with Filtration Membrane

Enrichment of cranberry juice in anthocyanins by electrodialysis with filtration membrane (EDFM) was investigated. Six filtration membranes (FM) with distinct constitutive materials and cut-offs were tested. The higher enrichment yields in anthocyanins (24 %) without any significant depletion of polyphenols from the raw juice were obtained with 2 filtration membranes: (1) polyvinyldiene fluoride (PVDF) with a cut-off of 150 kDa and (2) polyethersulfone (PES) with a cut-off of 500 kDa. It was also demonstrated that the enrichment in anthocyanins was influenced by the FM zeta potential (ZP). Indeed, for filtration membranes presenting positive surface charge (ZP close to 2-3 mV), repulsions would be established with anthocyanins positively charged and would avoid their electro-migration through the membrane. On the opposite, filtration membranes with moderate negative charges (ZP close to -5 mV) seem to facilitate the electro-transfer of anthocyanins through the membrane due to the force attraction between opposite charges.