Ultrasonic-Assisted Preparation of Maize Starch–Caffeic Acid Complex: Physicochemical and Digestion Properties

As an energy-saving and effective physical method, ultrasound technologies are gaining research attention for the production of modified starches. Corn starch–caffeic acid complexes are prepared via ultrasound process, and the effect of ultrasound power on the physicochemical properties and in vitro digestion of the complexes is investigated. The results of Fourier-transform infrared spectroscopy and the amount of complexes analysis indicate that ultrasound can help with the formation of starch–caffeic acid complexes, and the amount of caffeic acid in complexes depended on the ultrasound power. Scanning electron microscopy shows starch–caffeic acid complexes exhibit obvious dense network structure with increasing ultrasound power. X-ray diffraction results indicate the presence of V-type crystalline polymorph between starch and caffeic acid under high power of ultrasound irradiation. The starch–caffeic acid complexes can significantly inhibit the swelling power of starch granules at high temperature and increase the solubility of starch granules. Furthermore, the in vitro digestion of starch–caffeic acid complexes is estimated, and the result shows that the resulting complexes from ultrasound have lower digestion properties. Taken together, it is proposed that ultrasound technology is an effective method for preparation of starch complexes with potential as a functional food and drug delivery system.