Supercritical Fluid Extraction of Grape Seed Oil: Progress Report and New High Pressure Experimental Data

摘要

In the last decade liquid and supercritical carbon dioxide extraction of grape seed oil have been investigated by some authors experimentally and, by fewer, also theoretically and thermodynamically Experimental plants ranged from screening units to small laboratory plants; how the operative conditions affect the process has been underlined: pressure, temperature, size of the milled seed particles, humidity level The effect of adding a co-solvent has been reported The influence of the solvent flow rate and of the solvent direction (downwards or upwards) have been investigated, also by a model approach, The grape seed oil solubility has been calculated and modelled, showing a peculiar behaviour. On the other hand, just as in the case of traditional extraction processes, a sensitivity analysis has been able to point out a number of less understood questions: uncertainties regard, in particular, the transport mechanism details, simply summarized in an internal transport coefficient, as well as the dependence of this parameter on the particle diameter and time In this context, we performed some further dynamic experimental tests, also with the purpose of filling a pressure range not covered till now: pressure between 400 and 550 bar The substrate is represented by commercial available dried grape seeds, supplied by a distillery and normally sold to a food oil extraction company The grape seeds have been milled and sieved to obtain an almost uniform particle size, and their humidity level checked The extractor temperature has been fixed equal to 40 °C. Extraction curves show how increasing the pressure (in the range 350 - 550 bar) allows a certain solvent saving.