Selective anthocyanins enrichment of cranberry juice by electrodialysis with filtration membrane: Influence of membranes characteristics

Abstract : Enrichment of cranberry juice in anthocyanins by electrodialysis with filtration membrane (EDFM) was investigated. Six filtration membranes (FM) with distinct constitutive materials and cutoffs 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 cutoff of 150 kDa and (2) polyethersulfone (PES) with a cutoff of 500 kDa. EDFM treatment performed during 90 min did not affect the pH and conductivity values of the treated juices. The constant degree Brix obtained after EDFM treatment confirmed that this technology can selectively migrate anthocyanins without affecting the sugar concentration in the juice. Furthermore, the decrease in titrable acidity of the enriched juice improved its organoleptic characteristics. 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 À 5 mV) seem to facilitate the electro-transfer of anthocyanins due to the attraction between opposite charges.