Improving the extraction of α-tocopherol-enriched oil from grape seeds by supercritical CO2. Optimisation of the extraction conditions

In this work milled grape seeds from Vitis Vinifera were leached with supercritical carbon dioxide (SC-CO2) to assess the opportunity to obtain and α-tocopherol-enriched oil, having many potential uses in both the pharmaceutical and food industry.The extractions were carried out at the pressure of 25 MPa without pre-soaking to better reflect the prospective operation mode in a forthcoming industrial use. The obtained results were evaluated in terms of total amount of oil and total amount of α-tocopherol extracted from milled grape seeds as a function of particle size, extraction temperature and CO2 to seed mass ratio.The optimal extraction conditions were found to be 80 °C and ground seed fragment size in the range 300–425 μm; under these conditions the extracted oil contains as much as 265 ppm α-tocopherol.All the obtained results were compared to those of n-hexane extraction: the α-tocopherol concentration in the oil extracted with SC-CO2 is higher than that obtained by n-hexane, while the overall oil yield is lower.