Tailoring whey protein isolate properties through controlled cold plasma processing: excitation frequency, voltage and time as key variables.

Background: Cold plasma (CP) is a promising nonthermal technology for tailoring protein structure and functionality. Its ability to induce conformational rearrangements makes it a potential tool for improving the techno-functional performance of whey protein isolate (WPI). WPI was subjected to CP treatment under varying frequencies (50, 500 and 950 Hz), voltages (10, 15 and 20 kV) and times (10, 15 and 20 min). Analyses included secondary structure (Fourier transform infrared), zeta potential, surface hydrophobicity, carbonyl and free sulfhydryl contents, solubility and curcumin-protein fluorescence binding parameters.

Results: CP increased α-helix and β-sheet contents, promoting protein aggregation. Zeta potential was positively affected by higher frequency but reduced by higher voltage. Surface hydrophobicity consistently increased, while free sulfhydryl content decreased with frequency but increased with time and voltage. Carbonyl content rose under stronger treatments. Solubility decreased across all conditions, attributed to aggregation. Binding affinity (K_a) and number of binding sites (n) declined, indicating structural rearrangements and partial denaturation.

Conclusions: Controlled CP treatment significantly modified WPI structure and functional behavior, reducing solubility and binding affinity while enhancing aggregation. These findings demonstrate the potential of CP as a versatile tool to tailor protein properties for food applications. © 2025 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.