Fabrication, Structural and Emulsifying Properties of Egg White Protein-Dextran Conjugates through Maillard Reaction

Egg white proteins (EWP) are effective emulsifiers that can be used to form and stabilize oil-in-water emulsions. However, our previous study found that EWP was more suitable as an emulsifier to prepare emulsions under acidic conditions. In contrast, the physical stability of emulsions stabilized by EWP was poor under neutral conditions. To address this issue, we grafted dextran (Dex) to EWP at different mass ratios (EWP/Dex: 1:1, 2:1, 4:1, 10:1, w/w) using the Maillard reaction. The graft degree and molecular weight of the egg white proteins-dextran (EWP-Dex) conjugates increased with increasing mass ratio. The EWP molecules unfolded and exposed more hydrophobic groups during the conjugation process. Emulsions prepared using EWP-Dex conjugates, especially at a mass ratio of 1:1, exhibited better physical stability under neutral conditions than those prepared using protein alone. And they also exhibited stronger tolerance to changes in environmental conditions, including pH, salt, and temperature. Our results indicated that conjugation can be used to improve the functional performance of egg white proteins as an emulsifier.