Effect of Cetylpyridinium Chloride Surfactant and Polyethylene Glycol on the Process and Properties of Whey Protein Isolate Modification

This work studied the denaturation process of whey protein isolate (WPI) with the addition of cetylpyridinium chloride (CPC) surfactant and its combination with the plasticizer polyethylene glycol (PEG). Samples were prepared by dilution in water with different concentrations of CPC, with and without PEG, and were analyzed for miscibility and viscosity. Samples that proved to be miscible at this stage were subjected to thermal treatment for denaturing, dried, lyophilized, and ground. The effect of the process was evaluated by characterizing the samples by Fourier Transform Infrared Spectrophotometry, Differential Scanning Calorimetry, Thermogravimetry, and parallel plate rheometry. The results showed that there was an interaction between CPC and WPI, as well as between PEG and WPI in different ways and that there was a synergy between PEG and CPC in the interaction with WPI. The results showed that the CPC may have acted in such a way as to change part of the alpha-helix structure to the beta-sheet structure and the PEG acted in the protein's intramolecular interactions, but without changing the original structure. The rheological behavior, which means to evaluate the plastification of the material, showed the predominance of the elastic component (G ') concerning the viscous one (G '') for all samples. The use of CPC concentrations between 100 and 75 phr were the ones that resulted in a better ratio between G ' and G '' and a reduction in complex viscosity. The processing applied in the modification of the WPI influenced the interactions between the components.