Effect of Ultrasound Treatment Time on Physicochemical and Structural Properties of Lotus Root Starch

This study investigated the effects of different durations of ultrasound treatment (0, 10, 20, 30, 40 and 50 min) on the gelatinization, rheological properties, crystal structure, short-range ordered structure, and microstructure of lotus root starch (LS). The results showed that the molecular chain swelled and entanglement increased after ultrasonic treatment, and the gelatinization viscosity increased up to (6059 ± 31) mPa·s. Cracks, and collapses and holes appeared on the surface of starch particles, which promoted the entrance of water molecules and increase the viscoelasticity. Ultrasound treatment destroyed the α-1,6-glycosidic bonds of starch molecules, and broke some branches to form short starch chains, which were rearranged into ordered structures. The number of short-range ordered structures increased, and the R_1047/1022 ratio increased by 3.20%. Short-time ultrasonic treatment (30 min) enhanced the interaction between starch molecules, making the double helix structure more ordered and compact and increasing the T_p and ΔH by 11.09% and 89.21%, respectively. Long-time ultrasonic treatment (40–50 min) was not conducive to the formation of ordered structures. The results of this study can provide a theoretical basis for the application of ultrasonic in regulating the physicochemical properties and multi-scale structure of starch.