Microstructure, rheology and creaming stability of Pickering emulsions stabilised with SPI-soy peptide nanoparticle complex

The use of two emulsifiers to fabricate a composite emulsifier is a useful strategy used to strengthen the emulsifying capacity. To investigate the feasibility of using soy protein isolate (SPI) to stabilise Pickering emulsions stabilised by soy peptide nanoparticles (SPNs), the SPI was introduced into the SPN system to fabricate SPI-SPN complex emulsifiers, and the effects of the SPI on the properties of the SPNs and SPN-stabilised emulsions were investigated with various oil fractions. The addition of SPI significantly reduced the particle sizes and surface hydrophobicities. Furthermore, the SPI increased the structural rearrangements of the SPNs at the oil-water interface. Compared with emulsions stabilised with the SPN alone, the droplet sizes of the SPI-SPN emulsions were smaller, and the interface protein adsorption percentages were lower for all oil fractions. The viscosity of the SPI-SPN emulsion was higher than that of the SPNs emulsion at Phi <= 0.60. Decreases in G ' and G '' were observed when the SPI was added at all Phi values tested. More importantly, the added SPI markedly enhanced the creaming stabilities of the SPN emulsions at low Phi (<= 0.40). These results confirmed that SPI improved the emulsifying activity of the SPNs and enhanced the stabilities of Pickering emulsions stabilised with SPNs at low Phi.