Abstract:Whey protein isolate （WPI） were prepared into nanoparticles to improve its delivery application potential.Dynamic high pressure microfluidization （DHPM） was employed to modify WPI.The processing pressure，processing times，and protein concentration as the influencing factors were optimized via a response surface design with the average volume D（4，3）as the main evaluation index for the preparation of nanoparticles.The effects of DHPM on the structural properties of WPI were explored.The results showed that the best conditions for preparing the nanoparticles by DHPM were processing at the pressure of 127 MPa and protein concentration of 5% for three times，and its D（4，3） can be reduced to 169.85 nm.Compared with WPI before treatment，the WPI after appropriate DHPM treatment showed more concentrated particle size distribution，a decrease of 78% in polydispersity index （PDI），and an increase of nearly 16 times in the absolute value of Zeta potential.Structural analysis results showed that the processing increased the percentage content of the ordered structure α-helixes in WPI，enhanced the ultraviolet spectrum absorption intensity，moved the fluorescence absorption peak from 330 nm to 335 nm，and increased the endogenous fluorescence absorption intensity.In summary，appropriate DHPM treatment can expand the nanoparticle peptide chain and increase the orderly secondary structure of WPI.