RETENTION OF VOLATILE ORGANIC FLAVOUR FRAGRANCE COMPONENTS IN THE CONCENTRATION OF LIQUID FOODS BY OSMOTIC DISTILLATION/

Nine types of hydrophobic microporous membranes were tested for their influence on the retention of a range of volatile organic species when model aqueous solutions of the latter were subjected to osmotic disti llation. Similar studies were carried out on Gordo grape juice and Val encia orange juice. Gas chromatography-mass spectrometry head-space an alyses of the feed materials coupled with scanning electron microscopy and image analyses of the membranes used indicated that lower organic volatiles Aux to water flux ratios occurred when pore sizes at the me mbrane surface were relatively large. The results have been interprete d in terms of differences in feed-membrane and stripper-membrane bound ary layer resistances to organic volatiles transport resulting from di fferent degrees of liquid intrusion into the membrane pores. (C) 1998 Elsevier Science B.V.