The effect of ultrasound-assisted extraction of oil from safflower oilseed and physicochemical properties of oil and meal produced

Among of the emerging methods to increase the efficiency of oil extraction from oilseeds, the use of ultrasound has attracted the attention of researchers. In this study, bath ultrasound with frequency of 37 kHz was used and the variables included times of 30, 60 and 90 minutes and temperatures of 35, 45 and 55º C. Some physicochemical analysis were tested on the extracted oil and the remaining meal, and compared with the results of the traditional method (Soxhlet). Maximum oil efficiency in the ultrasound-assisted extraction (UAE) method was 17.4%. Ultrasound pretreatment did not have much effect on the composition of fatty acids, iodine value, refractive index and saponification value of the oil. However, the amount of free fatty acids, phosphatide and peroxide value increased with increasing time and temperature of pretreatment. The results of meal analysis showed that ash, crude fiber and crude protein were not affected by ultrasound. Trypsin inhibitory activity (TIA) was also measured and it was found that safflower seeds studied in this Research did not have TIA. The effect of this pretreatment on the urease activity was significant (P< 0.05) and reduced the activity of this enzyme, which is an undesirable and anti-nutritional factor. The results showed that UAE had no adverse effect on protein solubility of meal, and increased it under optimal conditions. The use of ultrasound pretreatment under optimal conditions increased the oil efficiency and reduced the extraction time, compared to the traditional method (Soxhlet), without having an adverse effect on the physicochemical properties of the extracted oil and residue meal.