Watermelon juice concentration using ultrafiltration: Analysis of sugar and ascorbic acid.

Raw watermelon juice was concentrated in a laboratory-scale flat-plate ultrafiltration system incorporating polyethersulfone membranes with a molecular weight cutoff of 5 kDa. The experiments have been carried out over a wide range of transmembrane pressures (100-300 kPa). The effect of ultrafiltration with molecular weight cutoff of 5 kDa polyethersulfone membrane on concentrate properties is reported. The total soluble solid content of the permeate was found to be very good, while the ascorbic acid content was on the lower side as compared to feed. The analyses of flux decay according to fouling models reported in the literature revealed that the formation of a cake layer covering the entire surface of the membrane is the main cause of the membrane fouling.