Effect of microwave-assisted phosphorylation modification on the structural and foaming properties of egg white powder

Egg white protein was phosphorylated with microwave assistance (200 W, 300 W, 400 W, 500 W and 600 W) in the presence of sodium tripolyphosphate at pH 8.0, and the structural and foaming properties of the protein were investigated in this work. The degree of phosphorylation increased at first and then remained unchanged. Fourier Transform infrared spectroscopy showed that egg white had new characteristic absorption bands by phosphorylation. Circular dichroism spectroscopy and surface hydrophobicity analysis revealed that the phosphorylated proteins had a more unfolded and flexible structure. The phosphorylated proteins had higher absolute values of zeta potential and a lower content of free -SH. After treatment with microwave at the 500 W level, phosphorylated protein had a 0.44 times (P < 0.05) greater foaming ability and 1.1 times (P < 0.05) greater foaming stability compared with the untreated sample. The results suggested that microwave-assisted phosphorylation modification is a practical method to improve egg white protein foaming properties.