Comparative Study of the Effects of Ultrasound and Microwave Treatments on Soybean Oil Extraction

The continuous need of human society to extract vegetable oils has led to many studies on the introduction of a more efficient and economical extraction process. The purpose of this study is to determine the effect of ultrasonic and microwave applications as new methods for extracting oil and also studying the physicochemical properties of the extracted oil using two ultrasonic and microwave pre-treatments. In this study, soybean oil was extracted by ultrasound at three different time intervals of 30, 60 and 90 minutes, and two different temperatures of 25 and 50 °C in the presence and absence of solvent. Microwave was also applied as heat pre-treatment at three different time intervals of 1, 3 and 5 minutes, and 180 watts in the presence and absence of solvent. Soxhlet method was applied as a mean to extract the oil. The physicochemical properties of the extracted oils were studied. In the present study, the ultrasound treated samples had the highest effect on oil extraction efficiency at 50 °C for 90 minutes by solvent-treated seeds, and this effect was significant (p <0.05). Ultrasound pretreatment increased oil pigments extraction in comparison with other methods and had less effect on acidity and peroxide values than microwave pretreatment. Microwave preheating and ultrasound were superior to Soxhlet's method alone in the extraction efficiency of soybean oil, and ultrasound pre-treatment showed the best results. Additionally, the microwave and ultrasound extraction methods did not have adverse effects on physicochemical characteristics of soybean oil.