PERVAPORATION OF GRAPE JUICE AROMA

Pervaporation of a model flavor compound of concord grapes (methyl ant hranilate) was evaluated with several membranes. Flux and selectivity decreased linearly with increase in downstream pressure, and increased with temperature. With a polydimethoxylsiloxane-polycarbonate membran e, increasing the feed concentration from 20 to 200 ppm did not affect the flux (55 g m(-2) h(-1)), but decreased the selectivity from 10 to 4. The presence of ethanol in the feed solution lowered separation fa ctors and increased total flux. A polyether block amide membrane gener ally gave higher flux and better selectivity. Experiments with commerc ial grape essence confirmed the excellent potential of pervaporation f or the production of highly enriched flavors.