Variation in the structure and emulsification of egg yolk high‐density lipoprotein by lipid peroxide

Abstract

To further clarify the effect of the oxidation of egg yolk high‐density lipoprotein (EYHDL) on the protein structure and emulsification, 2,2′‐azobis (2‐methylpropionamidine) dihydrochloride (AAPH) was selected as a representative lipid peroxidation‐derived peroxyl radical. The results of Raman spectroscopy indicated that, with the increase in the concentration of AAPH, the EYHDL carbonyl content increased significantly and the free sulfhydryl content declined sharply. Circular dichroism spectroscopy and intrinsic fluorescence indicated that exposure of EYHDL to AAPH led to destruction of the orderly structure and reduction of the structural stability. The particle size distribution and zeta potential indicated that the peroxyl radical caused molecular aggregation. Moderate oxidizing conditions can enhance the emulsification of EYHDL, and high‐intensity oxidation decreased emulsification. The research results indicated that EYHDL made a significant change in the oxidation system and led to a change in its structure and emulsification, providing a theoretical basis to clarify the EYHDL oxidation mechanism. Practical applications Egg yolk powder is prone to emulsification degradation during storage. The emulsification of egg yolk powder is mainly derived from high‐density lipoprotein in egg yolk. Moreover, egg yolk powder contains a large amount of lipids, and, during the processing and storage of egg yolk powder, many lipid peroxyl radicals are inevitably generated. Therefore, it is desired to combine the lipid peroxyl radicals generated during the storage of egg yolk powder with the decrease in emulsifiability. In this paper, we first investigated the effects of peroxyl radicals on the structure and emulsifying properties of high‐density lipoproteins and provided a theoretical basis to solve the problem that the emulsifiability of egg yolk powder is significantly reduced during storage.

Animal and Plant Protein Oxidation: Chemical and Functional Property Significance

“…There is limited information on the potential influence of oxidation on the functionality of egg yolk protein. Bao, Kang, Xu, Sun, and Lin [134] applied AAPH to modify the structure of egg yolk high-density lipoprotein and examined the impact on emulsifying capacity. Based on the results, the authors concluded that moderate oxidizing conditions (up to 0.2 mM AAPH) enhanced emulsification while higher dosages of AAPH (up to 10 mM) interfered with protein deposition at the interface leading to decreased emulsifying activity.…”

Elucidating the Calcium-Binding Site, Absorption Activities, and Thermal Stability of Egg White Peptide–Calcium Chelate

“…The Raman spectra of EWP and EWP-Ca were evaluated using the Horiba LabRAM HR Evolution micro-spectrometer (Horiba Jobin Yvon, France) as described previously [25].…”

“…Information about the structure and conformation of biomolecular can be obtained through Raman spectrum analysis [40]. As shown in Figure 4, the Raman spectral peak at the position of 1640 cm −1 is mainly caused by the stretching vibration of C=O, and the peak at the position of 1330 cm −1 corresponds to the symmetrical stretching vibration of the COO-of the amino acid side chain [25]; When the egg white peptide was binding with calcium, the peak intensities of C=O and COO-were decreased. Therefore, it can be concluded that carboxyl and carbonyl groups were the primary binding sites between EWP and calcium.…”

Effects of Peroxyl Radicals on the Structural Characteristics and Fatty Acid Composition of High-Density Lipoprotein from Duck Egg Yolk

“…HDL solution at 10 mg/mL was prepared, followed by adjustment of the pH to 8.0 to promote the dissolution of HDL. AAPH at different concentrations (0.05, 0.25, 1.25, 6.25, 12.5 mM) was added into HDL solution and the mixture was incubated at 37 °C for 24 h, followed by desalination using a dialysis bag [ 23 ]. The oxidized HDL powder was obtained from the resultant solution by lyophilization.…”