Effect of High-Pressure Homogenization on Rheological Properties and Multiscale Structure of Pea Starch

Pea starch (PS) was treated by high-pressure homogenization (HPH) at different pressures (0, 20, 40, 60, 80 and 100 MPa) three times for 30 min each in order to investigate the effect of HPH treatment on rheological properties and multiscale structure of starch. The results showed that the viscosity and thixotropy of PS initially increased and then decreased with increasing homogenization pressure. The frequency scanning results showed that the storage modulus G’ and loss modulus G” of PS gels were significantly increased after HPH treatment, and the viscosity and elasticity of PS gels were best after 40 MPa treatment. The G’ and G” curves of PS gels showed a turning point in the temperature range of 70–75 ℃. HPH treatment changed the granular morphology, crystal structure and short-range ordered structure of PS. Cracks, pits and holes appeared on the surface of PS granules after HPH treatment, and the particle size distribution changed. Through analysis by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy, it was found that the proportion of amorphous region of PS increased after 100 MPa treatment, and HPH treatment increased the ratio between peak areas at 1047 and 1022 cm^-1 (R_1047/1022) and the short-range ordered structure of PS. ¹H Nuclear magnetic resonance (NMR) spectroscopy showed that the α-1,4 glycosidic bond and α-1,6 glycosidic bond in PS were damaged, and the branching degree of PS was reduced. This study can provide a theoretical basis for the application of HPH in the regulation of starch rheological properties and multiscale structure.