Abstract: An osmotic concentration process for selectively extracting one or more volatile components from other components in a liquid mixture across a membrane structure which includes a semipermeable barrier film attached to a non-liquid-wettable microporous membrane is disclosed. The process includes the steps of:(a) contacting the liquid mixture with a surface of the semipermeable barrier film;(b) contacting a surface of the non-liquid-wettable microporous membrane with an extracting liquid in which one or more volatile components is soluble; and(c) collecting the remaining liquid mixture. As a result of the process the volatile component or components are extracted from the liquid mixture, passed through the membrane structure in a vapor phase and are dissolved in the extracting liquid. Also disclosed is a membrane arrangement for use in osmotic concentration of aqueous solution such as juice and other beverages, is constituted by a water-permeable sheet attached to a non-water-wettable microporous membrane.