Preparation and Emulsifying Properties of Maillard Reaction Products of Soybean Protein Isolate under High Hydrostatic Pressure

In this paper, the effects of high hydrostatic pressure (HHP) on Maillard reaction products of soybean protein isolate (SPI) and fructose (Fructose, Fru) at 60 ℃ under different pressures (0.1, 100, 200, 300 MPa) were studied. The grafting degree and emulsifying activity were used as indicators, and the structural properties of the products under the optimal conditions were analyzed. The results showed that under the conditions of pressure being 200 MPa, mass ratio 0.8:1, reaction time 24 h, and solution pH8.0, the emulsifying activity and emulsifying stability of the product were improved. The emulsifying activity was (85.36±0.04) m²/g, 1.71 times higher than the SPI and Fru mixture, 2.17 times higher than the SPI, and the emulsifying stability was (27.66±0.03) min, 1.15 times higher than the SPI and Fru mixture, and 1.40 times higher than the SPI. SDS-PAGE indicated that the sugar molecules were inserted into the SPI molecule through covalent bonds. Circular dichroism analysis showed that the secondary structure of modified SPI changed under the condition of 200 MPa. Endogenous fluorescence analysis showed that the spatial structure of SPI could be changed under 200 MPa. The particle size, potential and laser scanning confocal microscope micrographs showed that the stability of protein emulsion was improved by 200 MPa pressure.