Chua, H.T., Rao, M.A., Acree, T.E. and Cunningham, D.G. 1987.
Reverse osmosis concentration of apple juice: flux and flavor retention by cellulose acetate and polyamide membranes.
J. Food Process Eng 9(3): 231-45.
Apple juice was concd. in a pilot scale reverse osmosis unit using two com. spiral wound cellulose acetate membranes with 97% (CA-97) and 99% (CA-99) NaCl rejection ratings and an exptl. polyamide (PA-99) membrane with 99% salt rejection rating. Flux and concn. rates were higher for the PA-99 membrane than for the CA membranes. Gas chromatog. anal. of feed, permeate, and conc. samples was undertaken and a mass balance of odor-active volatiles was performed. The PA-99 membrane retained 45% of the total odor-active volatiles while the CA-99 retained 23%. Acetates were not found to increase when apple juice was concd. with the cellulose acetate membrane. Retention of individual aroma compds. for the CA-99 and PA-99 membrane was rationalized using polar, nonpolar, and steric parameters.