Diffusion of tocopherols, phospholipids and sugars during oil extraction from sunflower collets using ethanol as solvent

The ethanolic extraction of minor compounds (phospholipids, tocopherols and sugars) present in sunflower collets was studied at 50 and 60 °C in a batch reactor. The extracted material consisted of two phases: a hexane-soluble fraction, comparable to degummed sunflower oils, and a hexane-insoluble fraction high in phospholipids and sugars. Sugars were extracted in large proportion, especially the indigestible raffinose, increasing the nutritional value of the meal. The sugar reduction percentage in the sunflower collets increased over extraction time to up to 60 and 80% at 50 and 60 °C. The effective diffusion coefficient (De) for tocopherols was higher than that for phospholipids (3.950 10−9 and 2.596 10−9 m2/s, respectively), both being temperature-independent in the analyzed range. De of sugars was 6.50 10−10 and 1.51 10−9 m2/s for 50 and 60 °C, respectively. Using ethanol as extraction solvent could improve the oil and meal quality, and help obtain a third phospholipid-rich phase after fractionation.