Effects of dynamic high-pressure microfluidization treatment on the functional and structural properties of potato protein isolate and its complex with chitosan.

In our previous work, dynamic high-pressure microfluidization (DHPM) treatment was shown to promote the interaction between chitosan (CS) and potato protein isolate (PPI), but the modification mechanism of DHPM treatment (6 k-12 k psi) on PPI and its complex with CS remains to be elucidated. Here, moderate DHPM treatment (≤9k psi) was found to decrease the particle size, increase the surface charge, and improve the solubility of PPI and its emulsifying and foaming properties. The PPI functional properties were further improved by CS addition followed by DHPM treatment. The ultraviolet and fluorescence spectral results showed that DHPM treatment could destroy the PPI molecularstructure, while CS addition could provide a protective mechanism against PPI damage, which was also proved by the surface hydrophobicity. The circular dichroism spectral analysis exhibited that DHPM treatment could convert different types of secondary structures by disrupting the PPI intermolecular hydrogen bonds, while CS addition could promote the formation of hydrogen bonds in the system, which was also demonstrated by infrared spectroscopy. The sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) results exhibited that DHPM treatment (≤12 k psi) was not sufficient to reduce the PPI molecular mass, while DHPM treatment (6 k-12 k psi) could destroy the structure of CS/PPI complex. The thermodynamic analysis showed that the PPI thermodynamic stability could be improved by DHPM treatment, but decreased by CS addition plus DHPM treatment. These results showed that DHPM treatment has a good potential to modify the PPI and CS/PPI complex.