Surface characterization of 7S and 11S globulin powders from soy protein examined by X-ray photoelectron spectroscopy and scanning electron microscopy

In this study the surface composition of 7S and 11S globulin powders from soybean proteins by aqueous buffer and reverse micelle extractions had been examined using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Analysis by XPS revealed that the O and N atomic percentage of 7S and 11S globulin surfaces from bis(2-ethylhexyl) sodium sulfosuccinate (AOT) reverse micelle was higher than from aqueous buffer, but the C atomic percentage was lower. The O/C ratio of the 7S globulin powder from aqueous buffer and reverse micelle was similar while significant differences were obtained in the O/C ratio of the 11S globulin powder, N/C atom ratios of the 7S and 11S globulin powders and high-resolution XPS C 1s, N 1s, O 1s spectra. Powder microstructure after reverse micelle treatment showed the presence of small pores, indicating the effect of reverse micelle on the 7S and 11S globulin structure. The obtained results indicated that the reverse micelle could affect the C, O and N components on the surface of soybean proteins.

The surface composition of 7S and 11S globulin powders from soybean proteins using aqueous buffer and reverse micelle extractions was examined by X-ray photoelectron spectroscopy (XPS). As shown in the figure, the three predominant features were the C 1s, N 1s and O 1s peaks. The obtained results indicated that the reverse micelle could affect the distribution of C, O and N components on the surface of the 7S and 11S globulin powders.Figure optionsDownload as PowerPoint slideHighlights
► The effect of reverse micelles on the surface properties of protein powders was studied.
► Protein surface analysis was performed using X-ray photoelectron spectroscopy (XPS).
► Comparison was made between the surface properties of protein from aqueous buffer and reverse micelle extractions.
► The surface of protein from aqueous buffer and reverse micelle were observed by scanning electron microscopy (SEM).