adel bigbabaie

In this study, different electric field intensity (0.25, 3.25 and 6.25 kV/cm) and different number of pulse (10, 30 and 50) were used for optimizing the process of oil extraction from black cumin seeds using pulsed electric field pretreatment and then after using these pretreatments, the oil of seeds was extracted with screw press with different rotation speeds (11, 34 and 57 rpm), then parameters including oil extraction yield, color index, oxidative stability, refractive index and a and total phenolic of the extracted oil were studied. Statistical analysis and process optimization was performed with the use of response surface methodology (RSM). The results showed that oil color index increased with increasing of electric field intensity and the number of pulses, but oxidative stability of obtained oil decreased. The results also showed that the studied parameters had non-significant effects on the refractive index; moreover the oil extraction yield reduced by increasing the rotational speed of the screw press. Increasing the electric field intensity and the number of pulses to enhance the oil extraction yield and total phenolic was but a further increase of these variables, the two parameters decreased. According to the process optimization results, it might be stated that with applying electric field intensity for about 1.18 kV/cm number of pulse 48 and screw-rotation speed of the press of 11.01 rpm, the maximum oil extraction yield, oxidative stability and total phenolic components were reached.

Using modern methods including microwave, pulsed electric fields (PEF), ultrasonic waves often cause increasing of rate and efficiency of oil extraction. In this study, to evaluate the oil extraction rate from seeds of Nigella sativa, two pre-treatment processes i.e. pulsed electric field (electric field strength 3.25 kV / cm and the number of pulses 30) and microwaves (540 W power for 180 seconds) were used and after applying these pretreatments, oil seeds was extracted and the efficiency and effectiveness of screw type oil extraction process, the profile of fatty acids, tocopherols and the chemical compounds contained in black cumin oil were studied in a Completely Randomized Design with replications. The results showed that using of pulsed electric field and microwave pretreatments lead to increasing of efficiency and effectiveness of oil extraction. The major fatty acids of black cumin seed oil were linoleic acid, oleic acid and palmitic acid which using these pretreatments led to significantly (p