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As a nutritious and inexpensive source of protein, both the whites and yolks of eggs provide the body with quality nutrition. This study investigated egg white and yolk's protective and synergistic effects on immunity and intestinal mucosal barrier function in cyclophosphamide-induced immunosuppressed BALB/c mice. The results showed that egg white, yolk, and whole egg increased the level of cytokines [interleukin (IL)-2, IL-6, IL-10], interferon (INF)-γ and tumor necrosis factor (TNF)-α in the serum of mice. Also, the administration of egg white, yolk, and whole egg improved humoral immune status by increasing immunoglobulin levels in mice. The expression of CD4+ in the spleen were remarkably upregulated after feeding egg white, egg yolk, or whole egg. However, the whole egg was more effective in recovering damaged spleen and ileal tissues in mice than the egg white or yolk alone. [Display omitted] • Different components of eggs had a restorative effect on immunity. • Whole eggs were more effective than egg whites and yolks in restoring immunity. • Whole eggs promoted the recovery of specific and non-specific immunity. [ABSTRACT FROM AUTHOR]

The effects of lysozyme on egg white gel properties and their underlying causes were investigated under comparison between lysozyme removed with ion exchange resin and three levels of commercial lysozyme powder (1/2, 2/2, 3/2 the natural concentration in egg white) re-added in the lysozyme-removed system. Results showed that a lysozyme-removed gel obtained the best water holding capacity (61.61 %), lowest cooking loss (11.85 %), and enhanced textural properties (hardness, 638.04 g; resilience, 0.57; and gumminess), which was attributed to lysozyme promoting protein aggregation and weakening electrostatic repulsion by charge neutralization and competition for water, and this could be eliminated by removing lysozyme. Besides, the stronger intermolecular interactions (enhanced ionic bonds, hydrogen bonds and inhibited hydrophobic interactions), the shorter transverse relaxation time (T 21 and T 22), as well as more uniform microstructure formed in the lysozyme-removed gel, allowing the gels to bind more water molecules. With return of lysozyme, the gel properties were weakened to varying degrees, which was also ascribed to the filling of lysozyme in gel matrix narrowed interspace for binding and storage of water. In sum, adjustment on the content of lysozyme can regulate the gel properties of egg white, so as to obtain gels with regulable gel quality and processing characteristics. [Display omitted] • Egg white gel obtained the best water holding capacity(WHC) with lysozyme removed. • Lysozyme deteriorated egg white gel properties by promoting protein aggregation. • Excess lysozyme decreased the WHC by filling in its matrix, reducing water storage. • Egg whites can obtain better gel properties by adjusting lysozyme. [ABSTRACT FROM AUTHOR]

This work presents a novel use of fibrous egg white protein (FEWP) in food preservation and nutraceutical applications. In this study, food-grade FEWP was used as an encapsulating material, along with chitosan (CS), to stabilize emulsions. The emulsion system was then used as a delivery system to improve the stability of retinyl acetate (RA). The structural and functional properties, as well as the stability and rheological behavior of the FEWP/CS copolymer, was investigated. The stability of RA-enriched emulsions was also evaluated. FEWP and CS stabilized emulsions exhibited smaller particle size and enhanced stability against different ionic strengths and storage periods. Additionally, RA-encapsulated emulsions stabilized by FEWP:CS (25:1 w/w) effectively inhibited apple browning. This study provides a promising strategy for delivering antioxidant components, highlighting its potential in food preservation and nutraceutical applications. • Novel use of fibrous egg white protein enhanced retinyl acetate stability. • Fibrous egg white protein exhibited better emulsification properties. • Encapsulated retinyl acetate inhibits apple browning, promising food preservation. • Smaller particle size, improved salt and storage stability in emulsions. [ABSTRACT FROM AUTHOR]

Egg white, a crucial ingredient in bulk food production with limited emulsifying properties, can be significantly improved by fibrillation modification. However, resulting emulsions may exhibit instability at critical food processing pH values. In this study, the egg white protein fibril (EWPF) emulsion gel was constructed by Ca2+, and the stability enhancement mechanism under different EWPF and Ca2+ concentrations was investigated. The results showed that higher EWPF concentrations led to improved stabilization of the oil-water interface. At 60 mg/mL EWPF concentration, water loss decreased by 13.86% and oil loss by 35.79%, while the firmness and viscosity of the emulsion gel system were enhanced. The ζ-potential was reduced by 67.98% and the ionic bond content was increased by 22 times with the addition of Ca2+, the droplets showed a uniform cross-linked structure, and the stability and plasticity of the system were improved. By adjusting EWPF concentration to 40 mg/mL and Ca2+ concentration to 30 mM, pH stability of the system was also enhanced. This study provided a reference for the high-value utilization of egg white and a possibility for the application of EWPF in food processing, such as low-fat foods. [Display omitted] • The structure of emulsion gels can be modulated by EWPF and Ca2+ concentrations. • The water and oil loss rate of emulsion gels were improved by the addition of Ca2+. • Ca2+ made the structure of emulsion gel more compact and better stacking. • The emulsion gel was constructed by electrostatic forces and salt bridges. • The pH stability was markedly enhanced at 40 mg/mL of EWPF and 30 mM of Ca2+. [ABSTRACT FROM AUTHOR]

Abstract: Avian egg albumen participates in embryonic development by providing essential nutrients as well as antimicrobial protection. Although various biological functions of egg white proteins were suggested during embryogenesis, global changes of these proteins under incubation conditions remained uninvestigated. This study presents a proteomic analysis on the change of egg white proteins during the first week of embryonic development. By using 2-DE, together with MALDI-TOF MS/MS, thirty protein spots representing eight proteins were identified showing significant changes in abundance during incubation. An accelerating degradation of ovalbumin was observed in a wide range of molecular weight. In addition, four protein complexes were predicted according to the detected molecular weight increase. Among these speculated protein complexes, an ovalbumin spot coupled with RNA-binding protein was detected. The absence of these protein complexes before incubation, followed by the constant increase in abundance during incubation indicates conceivable pivotal roles in embryonic development. To better understand the function of the proteins identified in this study, discrepancies of egg white protein changes between fertilized and unfertilized chicken eggs were additionally demonstrated. These findings will provide insight into the embryogenesis process to improve our knowledge of egg white proteins in regulating and supporting early embryonic development. [Copyright &y& Elsevier]

Chicken eggs are often used as an ingredient in oil-containing aerated foods. Different egg yolk lipids have different influence on the foaming properties of egg white, but the exact mechanism behind this influence is not well understood. In this study, we aimed to investigate how high and low-density lipoproteins present in egg yolks impact the macroscopic foam characteristics, rheological properties, and air/water (a/w) interfacial behavior in egg white foams. We found that the addition of low-density lipoprotein (LDL) at a concentration as low as 0.1 % led to a significant decrease in foaming ability (FA) by 284.67–66.67 %. Conversely, high-density lipoproteins (HDL) improved the FA from 284.67 % to 340.67 % within the concentration range of 0.024–0.16 %. Rheological properties showed that the addition of LDL caused a decrease in the viscoelasticity of the interfacial membrane, while HDL had no significant effect on viscoelasticity. Interfacial behavior results suggested that LDL and HDL were detrimental to the diffusion of protein molecules at the a/w interface. This implied that the effects of LDL and HDL on the foaming properties of EWP were mainly due to the competitive adsorption of lipids and proteins at the A/W interface, as well as the interactions between them. This work provides new insights into the effect mechanism of different forms of egg yolk lipids on the foaming properties of egg white, which can be beneficial for regulating oil-containing aerated foods to meet production demands. [Display omitted] • A 0.1 % LDL reduced the foaming ability of EWP to a quarter of the original. • The low percentage of HDL allowed EWP to show excellent foaming ability. • EWP was competitively displaced from air/water interface by the lipid. • Mobility of the lipids induced the formation of a mobile air/water interfacial layer. [ABSTRACT FROM AUTHOR]

• CSEY gel moisture was further reduced due to salt permeation (egg white → egg yolk). • CSEY with a storage period (≤14 d) had good processing and eating value. • The quality of CSEY gel was seriously affected by salt penetration and water migration. • Ethyl acetate as the main flavor substance was not detected in CSEY-21 d sample. • Oxidation by air disrupted the hydrogen bonding force between lipoproteins. There is an urgent need to explore the salt penetration and water migration in the cooked salted egg yolk (CSEY) gel. The aim of this study was to investigate the effect of salt and water on the physicochemical, structural and flavor characteristics of CSEY gel stored at 25 °C. The hardness of the yolk increased significantly (608.0 g → 2730.7 g) during storage. The results of LF-NMR showed that the free water content in the yolk gel was enhanced. The microstructure of CSEY could be observed by SEM, which showed that during storage, polyhedral particles were dispersed due to the heating process. In addition, ethyl acetate (71.9 %) was completely undetectable in the CSEY-21 d. In summary, the sample at and before 14 d of storage had good processing value. Therefore, this work would provide theoretical guidance for the low-sodium pickling of SEY (salted egg yolk) and its suitable storage methods. [ABSTRACT FROM AUTHOR]

Egg white protein (EWP) has poor emulsification ability due to the hydrophobic groups buried in the molecular structure. In contrast, the protein fibrils produced by acidic heat treatment are able to expose the hydrophobic groups and firmly adsorb to the surface of oil droplets. Therefore, the preparation of egg white protein fibrils (EWPF) can broaden the range of applications of EWP, such as low-fat emulsion-based foods. Since the heating time affects the growth condition of the fibrils and thereby the properties of their stabilized emulsions. The effect of treatment time on the structure properties and emulsification properties of EWP during fibrillation, also the effect of different environments on the stability of EWPF emulsion were investigated. The EWPF content increased with heating time. During the heating of EWP under acidic condition, proteins were hydrolyzed into peptides, subsequently peptides aggregated unidirectionally to form fibrils due to electrostatic repulsive forces at low pH. Compared with EWP, EWPF had larger particle size, higher ζ-potential, higher β-sheet content and greater surface hydrophobicity. In addition, the emulsifying activity and emulsification stability of the EWPF emulsion increased nearly two-fold compared with that of the EWP emulsion. Furthermore, it had smaller droplets, higher ζ-potential, and better thermal and ionic stability. This study could provide insights into the improvement of EWP emulsifying properties and fibril-modified EWP as stabilizing ingredients for emulsion-based foods. [Display omitted] • EWP rich in acidic amino acids is an excellent material for fibrils preparation. • EWPF morphology gradually prolonged and aggregated with heating time. • The fine curled structure of EWPF can better encapsulate the oil droplets. • EWPF had the best emulsification properties when heated for 8 h. • Thermal stability and ionic stability of emulsion with EWPF were increased. [ABSTRACT FROM AUTHOR]

In this work, we studied foaming properties of egg white protein (EWP) under different physical modifications induced by supercritical carbon dioxide (SCCD), ultrasound, heat or high-pressure homogenization. Formation mechanisms of EWP aggregates and the relationships between processing parameters were discussed. Results showed that the maximum FC values were obtained via treatment with SCCD at 9 MPa (107.7%), ultrasound at 360 W (96.5%), heating at 45 °C (105%) and homogeneous pressure under 600 bar (87%), which were all dramatically higher than that of the control (29.9%). However, not all EWP treatments were conducive to the maintenance of foaming stability (FS). Results also indicated a close relationship between foaming properties and protein aggregation. Ovomucin in EWP might dissociate into small fragments or form new aggregates following treatment with SCCD, ultrasound or high-pressure homogenization, which caused a more dispersed particle size and decreased viscosity of EWP. Heating treatment greatly enhanced the viscosity of EWP, which was attributed to the irreversible destruction of the protein structure. Additionally, it seemed that SCCD maximally increased the FC of egg white through the synergy of selected pH and pressure treatments. Overall, using different physical treatments, it is possible to produce EWP with good foaming properties. • Egg White Samples were treated by four different physical treatments, respectively. • Foaming capacity (FC) was significantly promoted by different physical treatments. • The maximum of FC was obtained under 9 MPa supercritical carbon dioxide treatment. • Relationships between processing parameters and protein aggregation were discussed. [ABSTRACT FROM AUTHOR]

Lysozyme separated from egg white has high economic value and plays an important role in biochemistry, medicine and other fields. The role of lysozyme in the foaming properties of egg white was investigated in this study. After lysozyme being removed, the foaming ability (FA) and the foaming stability (FS) of egg white decreased by 45.1% and 35.3%, respectively, while restored again with lysozyme rejoining. In the absence of lysozyme, the particle size decreased and electrostatic repulsion increased, which resulted in a reduction of the protein adsorption on the interface of foam. Meanwhile, FTIR analysis showed the decrease on the protein secondary structure of α-helix and β-sheet. The reduction of hydrogen bonds played an adverse effect on the formation of stable interface. The decreased viscosity indicated the break of ovomucin-lysozyme complex, which was not conducive to the formation of viscoelastic film and leading to a reduction in FS. Furthermore, in the absence of lysozyme, the high surface tension value of the protein was harmful to the adsorption, stretching and rearrangement of protein molecules on the interface. This research provided a new opinion into the effect of lysozyme on the foaming properties of egg white. [Display omitted] • The foaming properties of egg white become worse with the elimination of lysozyme. • In the absence of lysozyme, the egg white foam becomes larger and sparser. • Electrostatic interaction mainly accounts for the impacts of lysozyme on the foaming. • The poor foam stability is due to the destruction of the lysozyme-ovomucin complex. [ABSTRACT FROM AUTHOR]

Supercritical carbon dioxide (SCCD) is a green, novel and practical technology in food processing. In this paper, SCCD treatment was used for enhancing the foaming properties of egg white. The possible mechanism of SCCD pressures increasing the foam ability of egg white protein (EWP) was discussed. The results showed that the maximal foaming capacity (107.7%) was obtained at 9 MPa, which was 3.6 times that of original egg white. Electrostatic force of protein molecules was reduced due to the change of pH value. Meanwhile, the particle size of EWP increased and the absolute zeta potential decreased with SCCD pressure increasing. These changes resulted in an increase of hydrophobicity and viscosity of EWP accordingly. This study found that SCCD treatment caused the exposure of EWP hydrophobic groups through the synergy of high pressure and CO 2 solvent. It provided a novel path to improve the foam ability of EWP by physical technology. • Egg White Samples were treated by supercritical carbon dioxide. • Foaming capacity was significantly promoted by SCCD treatment at 9 MPa. • Changes in physicochemical properties and protein structures were investigated. [ABSTRACT FROM AUTHOR]

• Egg White Samples were treated by supercritical carbon dioxide. • Foaming capacity was promoted by SCCD treatment. • Changes in physicochemical properties and protein structures were investigated. • Structural changes were confirmed by fluorescence and CD spectrum. The effect of supercritical carbon dioxide (SCCD) treatment at varying processing time (30–90 min) on foaming and structure properties of egg white protein (EWP) were studied in this paper. The highest foaming ability (107.7%) was obtained after 60 min SCCD treatment, which was 3.6-fold to the control group. Foaming stability kept stable under the processing time of 75 min. Results of surface tension, surface hydrophobicity, rheological properties and particle size indicated that protein was easier to spread to the gas-liquid interface and generate molecular rearrangement. Circular dichroism (CD) and Endogenous fluorescence spectrum showed that there were slight changes on the secondary structure of EWP. The α-helical structure of the protein was destroyed and the particle size became uneven, which indicated that the protein structure became more flexible and loose. The results of this study indicate that SCCD treatment had a potential to be implemented to enhance foaming properties of EWP. [ABSTRACT FROM AUTHOR]

This study was to evaluate the effect of ultrasound-assisted glycation with xylose on the foaming properties, physicochemical and structural characteristics of ovalbumin (OVA). The number of free amino groups in the glycated OVA (sOVA-X) significantly decreased with the increase of treatment time. The results obtained by circular dichroism (CD) and spectrofluorimetric measurements showed that there were slight changes on the subunits and secondary structure of OVA, indicating that the tertiary structure became more flexible and loose after the sonicated glycation treatment. The glycated OVA had higher solubility and foaming properties than the untreated samples. Therefore, ultrasound improved the glycation extent, and the changes in molecular structure were responsible for their different foaming ability and foaming stability. Our study also provided principle knowledge to understand how the viscosity and rheology were related to the foaming properties of OVA glycation by xylose. The results indicated that ultrasound-assisted glycation could be an excellent approach to improve the functional properties of OVA and promote its application in food industry. [ABSTRACT FROM AUTHOR]