Ultrafiltration of orange juice : effect on soluble solids, suspended solids, and aroma

Freshly squeezed orange juice was ultrafiltered in a hollow fiber cross-flow ultrafiltration system. The suspended solids (pulp) in the juice were completely separated with a membrane cutoff of 5×10 5 molecular weight. The membrane retained most of the pectin material, and the viscosity of the permeate (juice serum) was appreciably reduced. Concentration of permeate by evaporation was achieved up to 75 o Brix. No pectinesterase activity was detected in the permeate. Some aroma compounds, particularly hydrocarbons, remained in the retentate