The Effects of Ultrasonic Waves on Chemical Properties of Rapeseed Oil during Refining

The aim of this study was to investigate the effects of ultrasonic waves, reducing the temperature and lowering the time in the refining of canola oil, compared to the conventional method. In this study, an ultrasonic bath was used for degumming, neutralizing and oil bleaching. The temperature of 45 and 65 °C and time of 30 and 60 min for degumming, the temperature of 40 and 55 °C and time of 20 and 30 min for neutralization of degumming oil, the temperature of 45 and 60 °C and time of 20 and 30 min for bleaching of neutralized oil were used. At all stages, an ultrasonic bath with 100 Watts power and a frequency of 20 kHz was used. The acid index, peroxide value, and fatty acid composition of oils were determined. The acid index did not change significantly (p > 0.05) in the degumming process, but the peroxide value was increased (p < 0.05). In the process of neutralizing with ultrasound, the free fatty acid content was significantly reduced (p < 0.05), but the peroxide index was increased (p < 0.05). In the bleaching process by ultrasound, the free fatty acids and peroxide levels did not increase significantly in this treatment. The combination of fatty acids did not change with the ultrasonic waves after three refining processes. Ultrasonic waves can be used as a safe method in the process of oil refining and do not affect the composition of oil fatty acids.