The formation mechanism and thermodynamic properties of potato protein isolate–chitosan complex under dynamic high-pressure microfluidization (DHPM) treatment

Abstract The objective of the study was to explore the formation mechanism and thermodynamic properties of chitosan (CS)–potato protein isolate (PPI) complex under DHPM treatment. The transmission electron microscopic (TEM) results showed the formation of a complex between CS and PPI. Meanwhile, particle size and zeta-potential were shown to increase with increasing CS concentration, further confirming the formation of the complex. The surface hydrophobicity results showed CS was bound to PPI by hydrogen bond. The ultraviolet and fluorescence spectral analysis exhibited CS formed a protective mechanism against PPI destruction, preventing the exposure of tyrosine and tryptophan residues. Infrared spectrum and circular dichroism spectral analysis revealed no occurrence of chemical reaction between CS and PPI under DHPM treatment, further indicating that they are bound by hydrogen bond and hydrophobic interaction. Moreover, CS addition was shown to enhance the intermolecular interaction and promote the formation of intermolecular hydrogen bond network. Differential scanning calorimetry (DSC) and thermo gravimetric analysis (TGA) revealed that CS addition could improve the thermal stability of PPI. These results have shed light on the formation mechanism and thermodynamic properties of the CS/PPI complex and facilitate its application in food industry.