Pressurized Fluid Extraction of Pistachio Oil Using a Modified Supercritical Fluid Extractor and Factorial Design for Optimization

A pressurized fluid extraction (PFE) method for the extraction of pistachio oil was developed using a modified supercritical fluid extractor. The supercritical fluid extraction apparatus was modified to be able to pump liquid solvent and CO2 into the extraction vessel alternatively. The experimental results showed that the extraction yield was independent of the extraction pressure. It was also noticed that addition of glass beads increased the extraction yield by more than 15%, while the extraction reproducibility expressed by RSD was improved from 4% to 1%. Furthermore, the use of glass beads reduced the solvent consumption from 35 to 20 mL. The influence of the effective variables (i.e. temperature, time, and glass beads percentage) was optimized by a factorial design method. The model allows the prediction of the extraction yield at different conditions. The PFE of pistachio oil was found comparable in terms of the extraction yield (52.6%) and fatty acid composition with the Soxhlet method. Two different solvents of n-hexane and ethanol were used for PFE of pistachio oil. The extraction yield was about one third (i.e. 18%) when ethanol was used as solvent.