Effects of Ultrasonic Wave on the Properties and Structure of Cassava Starch
超声波对木薯淀粉性质及结构的影响

Cassava starch was treated by ultrasonic wave. The effects of ultrasonic wave on the physicochemical properties, crystal structure, granular morphology, amylose content and thermal properties of cassava starch were investigated respectively. The results indicated that apparent viscosity and shear-thinning nature decreased, and retrogradation increased with increasing ultrasonic treatment time. Starch paste showed higher transparency and lower enzyme resistance when ultrasonic treatment time was less than 2 min. However, continuously increasing ultrasonic treatment time would lead to increasing of transparency and decreasing of enzyme resistance. FT-IR and XRD analysis suggested that ultrasonic wave would not destroy functional groups of starch, but damaged crystal structure, as a result crystallinity decreased. SEM images indicated that more and more starch granules were fractured; many dents and splits were found on the surface of starch granules after ultrasonic treatment. Starch-iodine analysis suggested that ultrasonic wave destroyed amylopectin and starch chains, amylase content increased and degree of polymerization decreased. DSC spectra suggested that gelatinization enthalov remained the same. but gelatinization temoerature rised.