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

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.