Study on the differences in the effects of sulfite and protease on the structure and processing quality of high...

This study aimed to investigate the effects of sulfite and protease treatments on the molecular structure and processing quality of starch. Analyses showed that starch purity exceeded 90 % for both extraction methods. Compared with protease-extracted starch, sulfite-extracted starch exhibited a 0.05 % reduction in residual protein content. Fourier-transform infrared (FTIR) spectroscopy demonstrated that sulfite treatment hydrolyzed starch granular-associated proteins (SGAPs), which enhanced molecular ordering within the starch matrix. Sulfite-extracted starch also had higher solubility (over 4.8 %) and swelling degree (over 11.29 g/g) than protease-extracted starch. Electron microscopy revealed protein residues on the surface of protease-extracted starch granules. Additionally, protease-extracted starch exhibited higher peak viscosity, trough viscosity, and final viscosity than sulfite-extracted starch, with a lower hydrolysis rate in the first 30 min. These findings provide a foundational basis for advancing the functional applications and molecular-level investigations of these two starch types.