A study on pH-mediated variations and differences in the structure and function of hemp seed albumin, globulin, and protein isolate

In this comprehensive study, hemp seed protein isolate (HPI), albumin (ALB), and globulin (GLB) were prepared from hemp seed kernels. ALB was identified as a potential glycoprotein, distinguishing itself with a higher count of free sulfhydryl groups, fewer disulfide bonds, and a smaller molecular weight distribution. Conversely, GLB demonstrated fewer free sulfhydryl groups, a larger number of disulfide bonds, and a larger molecular weight distribution. HPI predominantly consisted of globulin with minor albumin. Varying pH from 3.0 to 9.0 considerably changed the structure and conformation of GLB and HPI but had minimal impact on ALB, according to surface hydrophobic, circular dichroism, and fluorescence spectrum assays. The pH-induced structural difference and variations in zeta-potential and solubility had synergistic effects on the emulsifying properties of GLB and HPI, while ALB's emulsifying properties were primarily associated with changes in zeta-potential and solubility. GLB and HPI demonstrated superior solubility and emulsification ability at pH 3. In contrast, ALB exhibited better functionality at pH 9. Understanding the pH-dependent properties of hemp seed proteins is crucial for optimizing their application in diverse fields.