Ultrasonication-assisted extraction of resveratrol from grapes

In order to search an effective extraction of resveratrol from grapes, superior to a conventional solvent extraction, an ultrasonication-assisted method was explored. When the new extraction of resveratrol was applied to fruit stem of Campbell and Gerbong grapes, the recovery yield was increased by 24-30%, compared to that by the conventional solvent extraction with ethanol/water (80:20%, v/v) maintained at 60 degrees C for 30 min. The ultrasonication-assisted extraction of resveratrol was modeled by the first-order reaction kinetics with reaction rate constants for extraction and degradation of resveratrol. For fruit stem of Campbell grape, the reaction rate constants k(1) and k(2) for extraction and degradation of resveratrol were 0.7797 min(-1) and 0.06481 min(-1), respectively, while the parameters for fruit stem of Gerbong grape were 0.4773 min(-1) and 0.03713 min(-1). In spite of the difference between two cultivars, the ratio of k(1) to k(2) was about 12 for both the cultivars. In simulation with the models for extraction and degradation of resveratrol. the maximum recovery of resveratrol from fruit stem of Campbell grape was 489.4 mu g/g-dry material at the extraction time of 3.48 min. For the same time, the amount of compounds degraded from the extracted resveratrol was 83.1 mu g/g-dry material. These figures indicated 79.8% and 13.6% of the total resveratrol in fruit stem of Campbell grape. Similarly, the maximum recovery of resveratrol for fruit stem of Gerbong grape and the amount of degraded compounds were 80.6% and 13.1%, respectively, of the total resveratrol, which were calculated with 194.8 mu g/g-dry material and 31.6 mu g/g-dry material. (c) 2005 Elsevier Ltd. All rights reserved.