A Membrane-Based Process for the Valorization of the Bergamot Juice

An integrated membrane process for the production of highly concentrated bergamot juice was investigated. The depectinized bergamot juice, with an initial total soluble solids (TSS) content of 95gkg-1 was previously clarified by ultrafiltration (UF) by using polysulphone hollow fibers membranes having a nominal molecular weight cut-off of 100kDa. The analyses of flux decay, according to fouling models reported in literature, revealed that the resistance of a cake layer covering the entire surface of the UF membrane well describes the fouling phenomenon in the treatment of bergamot juice. The clarified juice was concentrated in an osmotic membrane distillation (OMD) system by using a hollow fiber membrane contactor and calcium chloride dehydrate as extraction brine. In isothermal conditions (25°C) transmembrane vapor water fluxes were between 0.4 and 1.45kgm-2 h-1 producing a concentrated juice with a final TSS content of 540gkg-1. Suspended solids were completely removed in the UF process. Flavonoids and ascorbic acid were recovered in the UF permeate and well preserved during the subsequent concentration process. The evaluation of the total antioxidant activity (TAA) in clarified and concentrated samples confirmed the assumption of a mild integrated membrane process able to produce a concentrated juice without modifying the main quality criteria of the fresh juice.