Optimization of Canola Oil Extraction by Ultrasound Waves and Response Surface Methodology

Canola seed is one of the most important oil seed with high ratio of oil and high nutritional value and is economically recommended for cultivation and oil extraction. Extraction with ultrasound waves as a nondestructive and novel method might be employed. Therefore the aim of this research is optimization of extraction of canola oil by ultrasound waves and RSM.
In this project, Response Surface Methodology was employed for optimization of canola oil extraction by ultrasound waves using hexane and hexane/isopropanol as solvents by the ratio of 3:2 (v/v). The influence of extraction temperature in the range of 35, 45 and 55℃, ultrasound treatment time for 30, 60 and 90 minutes and ratio of solvent to canola in three levels of 5, 10 and 15 ml/g were analyzed by Box-Behnken Design (BBD) based on extracted oil percent. The fatty acid compositions of the extracted oils using ultrasound-assisted method and soxhlet method employing gas liquid chromatography were determined and compared.
According to the high values of correlation coefficients of selected models optimized for hexane solvent extraction methods (R2 =0.93) and hexane-isopropanol solvent mixture (R2 =0.97) and no significant lack of fit tests (P>0.05) selected models might be useful to predict the extraction percentage of canola oil.
The results showed that the optimum conditions for canola oil extraction by hexane (22.39 %) and combined hexane/isopropanol (30.66 %) were respectively at ultrasound treatment times of 69.5 and 87 minutes, temperatures of 55 and 55 ℃ and ratio of solvent to canola of 6.39 and 9.12 (%v/w). Extraction efficiency was significantly improved by ultrasound as compared to the soxhlet extraction. Fatty acid compositions of the canola oils were not significantly affected by the application of ultrasound (P> 0.05). Therefore ultrasound might be regarded as a simple and rapid method to improve the extraction of oil without affecting the quality of the fatty acids present.