Microwave-assisted extraction of stilbenes from woody vine material.

By-products from the winemaking companies, specifically woody vine material, can be an interesting source of bioproducts, specifically stilbenes and related compounds, however the extraction conditions can dramatically modify the final recoveries of these beneficial compounds. The effects of microwave-assisted extraction on the recovery of stilbenes have been evaluated in this manuscript. The stability under the extraction conditions was assessed in order to define the working range. A fractional factorial experimental design was developed to analyse the influence on the extraction process of seven different extraction variables: solvent, stirring, extraction temperature, extraction time, microwave power, sample weight and extraction volume. This new method enables stilbenes to be extracted from grape stems and canes in only 5 min, with an extraction temperature of 125 °C and 80% ethanol in water as the extraction solvent. Repeatability and reproducibility were also evaluated and the resulting RSD values (n = 5) were lower than 10% for all analysed stilbenes. Additionally, stilbenes in 20 different grape stem and cane samples were determined. [ABSTRACT FROM AUTHOR]