Insight into the non-covalent interaction mechanism between peanut protein and inulin

Cold plasma (CP) treatment was employed to induce the polymerization between peanut protein isolate (PPI) and inulin, thereby enhancing the solubility and functional properties of the peanut protein. Inulin was used to stabilize the surface stability of PPI via intermolecular interactions induced by CP polymerization. The results demonstrated that the soluble protein content of the PPI-inulin (PI) polymer was significantly increased to 4.28 mg/mL at 3 min of CP treatment. The emulsifying stability, quantified by Turbiscan Stability Index (TSI), reached optimal performance after 2 min of CP treatment, exhibiting a 45.58% reduction compared to untreated controls. Thermal stability analysis revealed that increased denaturation temperature (Td) and enthalpy change (ΔH) initially exhibited a partial correlation with the trend observed for solubility. Structural analyses indicated CP treatment enhanced exposure of hydrophilic groups in PPI secondary structures, while inulin's polyhydroxy architecture amplified complex hydrophilicity. In the tertiary structure, tryptophan and tyrosine residues were exposed, further promoting the interaction between the polymer and water molecules. There was no significant change in the FTIR spectra and SDS-PAGE electrophoretograms, confirming that CP did not cause significant stretching vibrations of the protein chemical bonds or alterations in the subunit structure. The improved performance of the PI polymer enhances the solubility and functional properties of peanut protein, which is of great significance for its broad application in the food industry.