Concentration of clarified orange juice by reverse osmosis

Concentration of orange juice by reverse osmosis (RO) was investigated. Pas teurised orange juice was filtered through microfiltration (MF) membrane (C eramic membrane, 0.2 mu pore size) and the filtrate was concentrated by rev erse osmosis membrane (TFC PA membrane. 98.6% NaCl rejection). It was possi ble to clarify orange juice to 100% transmittance at 660 nm by MF process c ontaining almost all the constituents except carotene pigments in the clear juice. Effects of (o)Brix or osmotic pressure (OP) of juice, operating tem peratures and transmembrane pressures [TMP] on RO permeate fluxes were stud ied. Permeate flux decreased as the (o)Brix and OP of the juice increased. Higher flux was observed at higher operating temperature and TMP. However, at higher (o)Brix values, the effect of temperature on flux was much less. It was possible to concentrate orange juice to 31 (o)Brix by RO at 60 bar a nd 32 degreesC with an average flux of 11 L/h/m(2). Retention of sugars and acid by the RO membrane was found to be more than 98%.