| A-tocopherol is one of the most important natural anti-oxidizing agent. Obtaining an oil enriched with this molecule by means of a renowned clean process could be very important for the food industry that could use it for fortification. In this work, milled grape seeds (Vitis vinifera), a residue obtained from the wine industry, were extracted with supercritical carbon dioxide (SC-CO2) as solvent, to determinate the optimal extraction conditions to obtain an a-tocopherol enriched oil. All the extractions were carried out at the pressure of 25 Mpa, based on earlier extraction of oil enriched in a–tocopherol from other seed matrices.
Both total oil and a-tocopherol extracted from milled grape seeds were determinated as a function of particle size , temperature and CO2 to seed mass ratio . The optimal extraction conditions were determined considering the maximum concentration of a-tocopherol in the extracted oil.
In the last years a variety of processes involving extraction with Supercritical Carbon Dioxide have been developped in the food industry, as promissing alternatives to the current conventional processes (distillation, solvent extraction, ecc.). Actually, SC-CO2 extraction offers many advantages, above all easy separation of the solvent from the extracted materials, leaving no residue of the solvent (which, anyway, is no toxic) in the processed materials and featuring a low extraction temperature, which minimizes thermal degradation of the products. Currently grape seeds, a residue of the wine industry, are industrially extracted with hexane, to obtain an oil which has many nutritional advantages for human consumption, owing to its high level of unsaturated fatty acids.
The objective of this study was to obtain a grape seed oil enriched in a-tocopherol, which is the isomer of tocopherols, with the highest vitamin E activity. The chemical structure of a-tocopherol is shown in Figure 67.
 FigFigure 67 : Chemical structure of a-tocopherol
Supercritical Carbon Dioxide extration has recently been applied to extract an oil enriched in a-tocopherols from other natural matrices, such as palm leaves, soybean flakes, rice bran and wheat germ, olive tree leaves.
Figure 68 : a-tocopherol concentration in the oil extracted using SC-CO2
SC-CO2 was used for milled grape seeds extraction in order to determinate the optimal conditions to obtain an oil enriched in a-tocopherol. The effect of particle size, temperature and CO2 to seed mass ratio has been analyzed. The experiments have demonstrated that SC-CO2 extraction can be used to obtain an oil enriched in a-tocopherol. The extracted oil, enriched in a-tocopherol, which is the isomer of tocopherols, with the highest vitamin E activity, could be very important for food industry, which could use it as a fortifying agent.
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