Effect of process parameters on transmembrane flux during direct osmosis.

Pineapple juices were concentrated by direct osmosis using aqueous solution of both sucrose (0-40% w/w) and NaCl (0-26% w/w) to overcome problems of low flux and salt migration. Effects of feed temp. (25-45C) and hydrodynamic conditions in the direct osmosis module on transmembrane flux were assessed during juice concentration to <less than or equal to>60Brix and physicochemical properties of resulting concentrates were determined. Results showed that transmembrane flux increased with both increasing feed temp. and Reynolds number. Pineapple juice concentrates obtained were characterized by good retention of ascorbic acid.