Liposome-whey protein interactions and its relation to emulsifying properties

The interactions between liposomes and whey proteins (WP) were investigated using sodium dodecyl sulfate polyacrylamide gel electropheresis, intrinsic fluorescence, Fourier transform infrared spectroscopy, circular dichroism spectroscopy, turbidity, particle size, and zeta potential. These results indicated that WP interacted with liposomes via electrostatic force, hydrophobic force, and hydrogen bonds. The interactions between WP and liposomes also led to the alteration of WP secondary structure, and it could be observed that the interactions induced an increase in random coil content at the cost of a decrease in α-helix. Furthermore, the emulsifying properties of WP significantly increased in the presence of liposomes. Emulsifying activity index and emulsifying stability index of WP increased from 12.12 to 20.36 m2/g, from 64.24% to 89.25%, respectively. However, the emulsifying properties of WP were also influenced by liposomal composition, pH, and temperature. The changes of WP structures were important reason for the changes of WP emulsifying properties. Our work provides new insights into the application of liposomes in food.