Effect of ultrasonic pre‐treatments on the octenyl succinic anhydride substitution of potato starch and its physicochemical and emulsifying properties

Summary To investigate whether the ultrasonic pre‐treatments of starch will affect the octenyl succinic anhydride (OSA) esterification, different power ultrasonic pre‐treatments (150, 300, 450 and 600 W) were performed on potato starch, then the OSA esterification was performed and the physicochemical as well as the emulsifying properties of the OSA starch were analysed. Results indicated that ultrasonic pre‐treatments decreased the degree of substitution and reaction efficiency by 30%, regardless of the pre‐treatments condition, while little differences were observed in the crystalline type and the long‐range ordered structure. DSC results demonstrated that low‐power ultrasound decreased the values of To and Tp, but increased ΔH, while high‐power ultrasound had the opposite effect. In addition, high‐power sonication improved the emulsifying capacity of OSA starch, which ranged from 189.08 ± 0.23 m2/g to 334.70 ± 0.35 m2/g, while emulsion stability decreased from 277.02 ± 10.83 min to 42.75 ± 0.08 min. Overall, the result of the present work implied that OSA starch exhibited varied thermal and emulsifying properties under different ultrasonic pre‐treatments, and our work might provide basic theory for the preparation of OSA starch. The OSA‐starch were prepared with ultrasound treatments and then the physicochemical characterizations were performed and the emulsifying property and stability were evaluated. Results found that OSA starch exhibited varied thermal and emulsifying properties under different ultrasonic pre‐treatments.