Improvement in emulsifying properties of soy protein isolate by conjugation with maltodextrin using high-temperature, short-time dry-heating Maillard reaction

Soy protein isolate (SPI)-maltodextrin (MD) conjugates were synthesised using Maillard reaction under high-temperature (90, 115 and 140 degrees C), short-time (2h) dry-heating conditions. The loss of free amino groups in proteins and sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) profile confirmed that SPI-MD conjugates were formed and higher dry-heated temperatures could increase the glycosylation degree. The emulsifying properties of SPI and SPI-MD conjugates were evaluated in oil-in-water emulsions. The emulsions stabilised with SPI-MD conjugates synthesised at 140 degrees C exhibited higher emulsifying stability and excellent storage stability against pH, ionic strength and thermal treatment compared with those synthesised at 90 degrees C, 115 degrees C and SPI stabilised emulsions. This might be due to a greater proportion of conjugated MD in SPI-MD conjugates synthesised at 140 degrees C because of the higher glycosylation degree, and more conjugated MD on the droplet surface could provide steric effect and enhance the stability of the droplets in the emulsions.