Extraction of Bioactive Compounds from Milled Grape Canes (Vitis vinifera) Using a Pressurized Low-Polarity Water Extractor

Trans-resveratrol and trans-epsilon-viniferin were extracted from milled grape canes using pressurized low-polarity water. The effects of temperature were significant for both compounds (p a parts per thousand currency signaEuro parts per thousand 0.05): extraction at 160 A degrees C resulted in a 40% loss of trans-resveratrol compared to 95 A degrees C while reduction of trans-epsilon-viniferin at both temperatures remained at 30%. Increasing ethanol concentration from 0% to 25% increased the extraction of total phenolics and trans-epsilon-viniferin by 44% and 489%, respectively. Solvent flow rate also influenced trans-epsilon-viniferin extraction. Antioxidant activity showed a strong correlation with total phenolic content of the extracts, and the two target phenolic compounds. Except for the modifier concentration, the extraction parameters studied were not statistically significant with respect to the antioxidant activity of extracts (p > 0.05). Effective diffusivities of trans-resveratrol multiplied from 3.3 x 10(-11) to 10.4 x 10(-11) m(2)/s by three times with increasing temperature. The modified Gompertz equation satisfactorily explained the extraction of the stilbenes investigated.