The effect of temperature and amplitude of pulsed ultrasound on yield, kinetics and extraction thermodynamics of solvent extraction of grape (Siah-Sardasht cv.) seed oil

In this study, the effect of three levels of temperature (30, 40, and 50°C) and seven amplitudes of pulsed ultrasound (0, 20, 30, 40, 50, 70 and 100%) on yield, kinetics and extraction thermodynamics of solvent extraction of black grape seed oil (Siah-Sardasht cv.) was evaluated. In addition, the kinetics of oil extraction were studied based on a second order reaction. According to the results, the highest oil yield of 16%, was obtained at several amplitude of pulsed ultrasound and at 50°C. In all treated and untreated samples, the extraction capacity (cs), extraction rate constant (k) and initial extraction rate (h) were increased by increasing temperature. The increase of cs and k in all treated samples by ultrasound was more than that of control ones and the identical results were found for h in most treated samples. The thermodynamic factors of the extraction process showed that samples treated by pulsed ultrasound have lower activation energy (Ea) and enthalpy ( Δ H) than control, and the same results were observed for frequency factor (A) in most treated samples. However, pulsed ultrasound-assisted solvent extraction had no effect on entropy ( Δ S ). Pulsed ultrasound-assisted solvent extraction increased kinetics in comparison to yield in the grape seed oil extraction.