Morphological, physicochemical, and viscoelastic properties of sonicated corn starch.

In the present work, different parameters of ultrasound treatment were studied for physical modification of corn starch. The results revealed that the influence of sonication strongly depends on temperature (25-65 °C) and exposure time (5-15 min), while concentration (10-20% w/w) and ultrasound amplitude (50 and 100%) have little influence on functional and rheological properties. SEM micrographs demonstrated the damage induced by ultrasound on starch granules' surface. The solubility, swelling power, and gel clarity were increased. Ultrasonication decreased the gelatinisation enthalpy and temperature range while the X-ray pattern and crystallinity remained almost unchanged, except for samples treated at onset temperature as measured by DSC. The pseudoplasticity and consistency coefficient decreased; also, apparent viscosity diminished prominently. The pasting behaviour of samples was altered without any clear change in gel strength characterised by loss factor. The results of the present work provide further insight into the mode of action of ultrasound on modifying corn starch granules.