| Popis: |
Grape seed fraction of the pomace represents valuable wine waste by-product, not just as a source of polyphenolic compounds, but also since it contains 7-22% of oil. Compared to solvent extraction methods, supercritical CO2 extraction (SC CO2) represents promising alternative, eco-friendly technique of extraction, since it involves green, low-cost, non-toxic and non-flammable CO2 as solvent/extraction fluid. Consequently, low processing temperatures make this technique suitable for preservation of thermosensitive compounds. In addition, higher extraction yields were obtained compared to cold pressing, but impact on the overall quality of grape seed oil was not profoundly studied. The aim of this study was to investigate the impact of different SC CO2 extraction variables (pressure, temperature, and CO2 flow rate) on the oil yield (%) and oil antioxidant capacity (ORAC). The experiments were performed on Graševina grape seed pomace according to Box-Behnken design, while optimization of SC CO2 extraction was conducted by response surface methodology (RSM). The pressure of the extraction showed to be the most significant variable influencing the oil yield (p < 0.01). In addition, besides the pressure (p < 0.05), CO2 flow rate (p < 0.001), as well as interaction among flow rate and temperature (p < 0.05) significantly influenced the ORAC values. The optimal conditions obtained by RSM from SC CO2 extraction of grape seed oil from pomace were 450 bar, at 40 °C, with CO2 flow rate at 45 g/min, in order to achieve maximum extraction yield (7.82%) and ORAC value (415.24 μM Trolox equivalent/100 g oil). Experimental data were in accordance with the predicted ones since the obtained data were not significantly different within the 95% confidence interval. |
