Effect of ultrasound treatment on the physicochemical and structural properties of long-chain inulin

In this study, ultrasound was employed to radiate long-chain inulin suspensions in order to obtain some new physicochemical properties. The results showed that ultrasound irradiation effectively improved the viscoelasticity of long-chain inulin samples. The samples achieved the greatest increase in the apparent viscosity and viscoelasticity after 10-min ultrasonic treatment at the intensity of 1734.9 W/cm2. In addition, Fourier transform infrared spectroscopy (FTIR) spectrum analysis revealed that ultrasound could not change the functional groups and molecular structure of long-chain inulin, only effect the hydrogen bonds of long-chain inulin. The results of X-ray diffraction (XRD) indicated that ultrasound also affected the relative crystallinity of long-chain inulin, depending on its intensity and treatment time. Particle size distribution indicated that long-chain inulin with particle size of 100–300 μm formed after ultrasound treatment. The changes in inulin particle size showed that inulin was unfolded by ultrasound treatment at low intensity for a short time and then aggregated with enhanced ultrasound effect. These results suggested that ultrasound treatment can change the physicochemical and structural properties of long-chain inulin, which would facilitate long-chain inulin application in the food industry.