Selective anthocyanins enrichment of cranberry juice by electrodialysis with ultrafiltration membranes stacked

Cranberry juice is well known for its nutritional and health benefits. The possibility of selectively enriching the juice in polyphenols (anthocyanins and proanthocyanidins) without affecting the sugar concentration represents a relevant industrial opportunity to develop a new nutraceutical product. A preliminary study demonstrated the feasibility of enriching a cranberry juice fraction in natural polyphenols from a larger bulk quantity of cranberry juice by electrodialysis with one ultrafiltration membrane stacked (EDUF1M). However, the efficiency of this enrichment was limited by the fouling of membranes and the depletion of the original polyphenols from the raw juice. To overcome these constraints, the aims of the present work were to 1) increase the filtration area by stacking 3 ultrafiltration membranes in an EDUF configuration (EDUF3M), 2) investigate the effect of two distinct volume ratios: 10 and 30 (volume of raw juice / volume of enriched juice) and 3) better understand the polyphenols – ultrafiltration membrane interactions. Surprisingly, no significant enrichment in anthocyanins was obtained with EDUF3M configuration after 30 min (ratio 10) of treatment, while a 22 % enrichment yield was achieved after 1 h30 (ratio 30), without any significant exhaustion from the raw juice. The fact that soluble sugars (°Brix) concentration remained constant in raw and enriched juices demonstrated that this technology can selectively cause the migration of anthocyanins from one side of the membrane to the other, leaving sugar concentration constant. The performances of cranberry juice enrichment by EDUF3M process are affected by the treatment duration and polyphenols adsorption on ultrafiltration membranes as suggested by the increase in their zeta potential after incubation in cranberry juice.Industrial relevance: Electrodialysis with ultrafiltration membrane (EDUF) is an innovative electromembrane technology that allows the production of a cranberry juice enriched selectively in anthocyanins without affecting sugar concentration. This technology represents a relevant industrial opportunity to develop new nutraceutical products.

► A 22 % enrichment yield was achieved after 1 h30 (ratio 30) ► Soluble sugars concentration remained constant ► this technology can selectively cause the migration of anthocyanins ► EDUF3M process is affected by treatment duration and polyphenols adsorption ► Increase in zeta potential of UF membrane after incubation in cranberry juice