Combining high-pressure methods for extraction of stilbenes from grape cane

Stilbenes were extracted from grape cane using supercritical fluid extraction and pressurized liquid extraction, and the extracts were analysed by HPLC. The results of the high-pressure experiments were compared with ethanolic Soxhlet extraction, which yielded 2.31 mg/g dw trans-resveratrol, 1.56 mg/g dw trans-epsilon-viniferin, and 0.69 mg/g dw r2-viniferin. In contrast to resveratrol, the extraction of viniferins with supercritical CO2 required a high concentration of ethanol as co-solvent. Its increase from 15 to 20% at 30 MPa and 50 degrees C increased the rate of extraction of trans-epsilon-viniferin and r2-viniferin 4 times and 7 times, resp. The optimal conditions of pressurized liquid extraction were: ethanol as solvent, pressure 10 MPa, and temperature 100 degrees C for resveratrol and 80 degrees C for viniferins. The selectivity of supercritical fluid extraction and efficiency of extraction with pressurised ethanol were combined to obtain extracts of different mutual ratios of stilbenes.