Characterization and emulsion stability of soybean protein isolate/soybean peptide and ginseng polysaccharide conjugates

This study investigated glycosylation products via the Maillard reaction involving soy protein isolate (SPI)/soy peptide (SP) and ginseng polysaccharide (GP), examining their potential to enhance emulsion stability. SP-GP exhibited the highest grafting degree (55.69 ± 1.48%) in a notably brief reaction time (35 min) compared to SPI-GP (45 min). The amino acid compositions, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) imaging, scanning electron microscopy imaging, and circular dichroism spectroscopy verified the formation of SPI-GP/SP-GP conjugates. SDS-PAGE showed that SPI-GP and SP-GP formed new bands, with molecular weights exceeding 254 and 45 kDa, respectively. The highest grafting degree in SP-GP resulted in the largest proportion of random coil (10.97 ± 0.82%). SP-GP achieved the highest emulsifying activity (31.26 ± 0.68 m2/g) at pH 9. Notably, using SP-GP as an emulsifier resulted in the most homogeneous emulsion with the smallest particle size (2.10 ± 0.02 μm), smallest span (1.32 ± 0.02), and highest absolute Zeta potential (50.20 ± 0.87 mV). Its creaming index remained at 0.00% for 21 days. SP-GP's inclusion curbed oxidation reactions and significantly amplified the overall emulsion stability. Consequently, the remarkable attributes of SP-GP position it as a highly promising emulsifier for employment in emulsion preparation.