Ultrafiltration of Clementine mandarin juice by hollow fibre membranes

Modified poly(ether ether ketone) (PEEKWC) and polysulphone (PSU) hollow fibre (HF) membranes were prepared via dry-wet spinning technique through the phase inversion process and characterised by pure water permeability, dextran rejection and scanning electron microscopy (SEM). The performance of the membranes, in terms of permeate flux an quality of permeate, was studied for clarification of Clementine mandarin juice. Experiments were performed in selected operating conditions according to the batch concentration procedure up to a final volume reduction factor (VRF) of 2. The permeate flux profile observed with the PSU membranes was lower than that observed with the PEEKWC membranes. Almost all total soluble solids and citric acid of the original juice were recovered in the permeate. The resulting juice after filtration showed a complete removal of suspended solids with a consequent improvement of colour and clarity. PEEKWC membranes showed a lower rejection towards antioxidant compounds (21.8%) in comparison with the PSU membranes (32.0%).

3.6 100.0 Á Á 8.2 21.8 Clementine mandarin juice was clarified by using PEEKWC and PSU hollow fibre membranes prepared in laboratory. PEEKWC membranes showed higher steady-state permeate fluxes in comparison with PSU membranes in the selected operating conditions. Color and clarity of the juice were improved after filtration with both membrane modules because of the removal of suspended colloidal particles and higher molecular weight soluble solids of the juice. Acidity, pH and soluble solids did not change during the processing and presented average values of 0.76 Á 0.80% w/w citric acid, 3.35 Á 3.40 and 10.6 Á 118Brix, respectively. Therefore, the clarified juice retained the food value of the original juice. However, in the clarified juice obtained with PEEKWC membranes a higher recovery of antioxidant compounds, especially in terms of total phenolic compounds, was observed in comparison with the PSU membranes.