PERMEATION OF APPLE AROMA COMPOUNDS IN REVERSE-OSMOSIS

This work studies the permeation of apple juice aroma compounds throug h a reverse osmosis spiral wound aromatic polyamide membrane of 99.2% NaCl rejection. A model solution of apple juice aroma was used as feed . Experiments were carried out at different transmembrane pressures (1 .5-3.5 MPa) and feed flows (200-600 1/h; Reynolds numbers between 100 and 300). Temperature was set at 25 degrees C. Rejection was observed to increase with transmembrane pressure and feed flow. The preferentia l sorption-capillary flow model was used to estimate the experimental rejection using only data on the permeation of a solute taken as refer ence (NaCl) and on the permeation of pure water. Good agreement betwee n experimental and estimated rejection was found for the most hydrophi lic aroma compounds, while a slightly higher rejection than the experi mental one was predicted for the least hydrophilic compounds. (C) 1998 Elsevier Science B.V. All rights reserved.