Interaction between soy protein isolate/whey protein isolate and sucrose ester during microencapsulation: Multi-spectroscopy and molecular docking

Proteins serve as commonly utilized wall materials in the process of spray drying microencapsulation. However, proteins exhibit increased sensitivity to the environment, thereby impacting the stability of microcapsules. In this work, to improve the functional properties of proteins, whey protein isolate (WPI)/soy protein isolate (SPI) were combined with sucrose esters (SE) to investigate their interaction during spray drying. Spectroscopic studies revealed that SE is capable of inducing conformational changes in SPI and WPI, resulting in a decrease in their fluorescence through a static quenching mechanism. The formation of protein-sucrose ester complexes was confirmed using SDS-PAGE electrophoresis. Increasing the SE ratio resulted in a decrease in particle sizes of the SPI–SE and WPI–SE complexes, damaging the particles. Molecular docking simulation experiments were conducted with SE using 7S, 11S, and β-LG proteins. The results revealed the presence of hydrogen bonds, salt bridges, and hydrophobic interactions between SE and the 7S protein; hydrogen bonds, cation–π interactions, and hydrophobic interactions between SE and the 11S protein; as well as hydrogen bonds and hydrophobic interactions between SE and β–LG. These findings offered valuable insights for the development of novel formulations for food microencapsulation through spray drying.