Effect of ultrasonic vacuum drying on the structural characteristics of whole-egg protein powder

This study investigated the effect of single- and dual-frequency ultrasonic vacuum drying on protein structure, endogenous fluorescence spectrum, surface hydrophobicity, sulfhydryl group content, emulsification, and emulsification stability of whole-egg powder. Experiments were carried out using the infrared spectroscopy, fluorescence spectroscopy, and ammonium salt of 8-phenylamino-1-naphthalene sulfonate (ANS) fluorescent probe methods. The ultrasonic treatment changed the secondary structure of proteins in whole-egg powder, increasing the content of α-helix, random curl, and β-rotation structures, and decreasing β-folding content. Ultrasonic treatment promoted the gradual transformation of the disulfide bond conformation of the sample from the twist-twist-twist conformation to the twist-twist-trans. Tyrosine and tryptophan residues in the samples were exposed, and the intensity ratio of the Fermi resonance spectra of tryptophan (I₁₃₆₃/I₁₃₃₈) in the single-frequency treatment, dual-frequency treatment, and the control group was significantly different (P