The effect of power ultrasound on physicochemical properties and oxidative stability of interesterified soybean oil

The objective of this study was to evaluate the effect of power ultrasound on the physicochemical properties and oxidative stability of an interesterified soybean oil (IESBO). IESBO was crystallized at 32 °C and sonicated for 10 s with acoustic power of 101 W. The sonicated IESBO was tested for morphology, elasticity, melting behavior and chemical composition and compared to those of the non-sonicated IESBO to determine what physical and chemical changes manifest as a consequence of sonication. Application of power ultrasound had significant effects on the physical properties of IESBO. The sonicated IESBO showed smaller crystals and was harder than the non-sonicated IESBO. Sonication increased elasticity (G\u27; storage modulus) of the IESBO from 194.9±17.9 to 597.2±159.6 Pa. Sonication also affected the melting behavior of the crystallized fat when the melting behavior of sonicated stearin fraction (crystals) was evaluated. Stearin fraction of the sonicated IESBO showed a sharper and narrower peak than that of the non-sonicated IESBO. However, sonication did not affect its chemical composition, which was determined by fatty acid methyl ester compositions of the stearin fractions with and without sonication. The oxidative stability of the sonicated IESBO was measured using peroxide value (PV) and then compared to that of the non-sonicated IESBO and liquid soybean oil (SBO) which had been stored at 25 °C for 105 days followed by storage at 40 °C for 42 days. Power ultrasound did not cause accelerated oxidation in the SBO or IESBO until they were highly oxidized (PV \u3e 10 mequiv/kg). At high levels of oxidation, the non-sonicated IESBO had significantly higher PV than the sonicated IESBO, while the non-sonicated SBO had significantly lower PV than the sonicated SBO