Extraction of oil from Pistacia khinjuk using supercritical carbon dioxide: Experimental and modeling

In the present work supercritical fluid extraction (SFE) with carbon dioxide was performed to obtain oil from Pistacia khinjuk (P. khinjuk) stocks fruit, for the first time. Response surface methodology (RSM) was used to optimize the process and evaluate the effect of different operating parameters including pressure (12-24 MPa), temperature (35-55 degrees C), flow rate (2-6 g/min) and extraction time (0-300 min) on the total oil yield. The relationship between the yield of P. khinjuk fruit oil and the extraction variables was determined by a second order poly-nominal equation applying the central composite design (CCD). The maximum oil yield was found to be 78.10 wt% under optimal conditions pressure of 23.39 MPa, temperature of 55 degrees C, CO2 flow rate of 4.37 g/min and dynamic extraction time of 286.45 min. Sovova's mathematical model was applied to describe adequately the kinetic behavior of the extraction process. The concentration of hardly accessible solute (x(k)), the mass transfer coefficients in the fluid phase (k(f)) and solid phase (k(s)) as well as the oil solubility in supercritical CO2 (y(r)) were used as fitting parameters. The chemical composition of the extracts was identified by gas chromatography spectrum (GC) analysis. Moreover the physicochemical properties of the oil samples were measured to characterize the oil quality. The desired and promised nutritional properties of the oil proposed that it can be considered as a good product in the future food industry. (C) 2015 Elsevier B.V. All rights reserved.