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This paper was dedicated to the study of the effect of sucrose-phosphate on aspects of physicochemical properties, lipid distribution and protein structure during the picklig of reduced-salt salted egg yolk (SEY). This work constructed a reduced-salt pickling system from a new perspective (promoting osmosis) by using a sucrose-phosphate-salt. Results showed that SEY-28d achieved a desirable salt content (1.07 %), hardness (573.46 g) and springiness (0.65 g). The matured SEY was in excellent quality with orange-red color and loose sandy texture. This was because the lipoprotein aggregated with each other through hydrophobic interaction to form a stable network structure. In addition, the hypertonic environment accelerated salt penetration. These also created good condition for lipid spillage. The results of confocal laser scanning microscope also verified this phenomenon. This work provides important guidance for new reduced-salt curing of traditional pickled foods, deep processing of SEY, and industry development in the field of poultry egg., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Xylitol and NaCl were studied as alternative inhibitors of gelation in frozen egg yolks, considering the current dietary preference for low salt and low sucrose intake. The effects of different ratios of xylitol and NaCl on gelation were investigated. Compared to the control group, all treatment groups showed decreased egg yolk particle size and turbidity, increased solubility, surface hydrophobicity, λ max , and fluorescence intensity, reduced loss of free water, and enhanced yolk fluidity. The addition of xylitol and NaCl effectively prevented ice crystal growth, minimized protein denaturation caused by water loss, and formed complexes with proteins and water lost during freezing, thereby inhibiting the aggregation of protein molecules and the formation of gels. This study presents a novel and healthier strategy for inhibiting gelation of frozen egg yolk using xylitol and NaCl., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

The use of safe physical means to achieve egg yolk as natural carrier for active ingredients plays an important role in increasing the added value of egg yolk. In this paper, we prepared DHA-fortified egg yolk emulsion using high-speed shearing (HSS) only and HSS combined with high-pressure homogenization (HPH), respectively. HPH reduced particle size and zeta potential, allowing for better emulsion stability. After 14 days of storage, the encapsulation efficiency was 93.88% even with 15% (w/w) algae oil addition. Rheology analysis presented that HPH improve the viscoelasticity, indicating the enhancement of interaction force between droplets. Then, vaccum low-temperature spray drying (VLTSD) was used to produce powder, which allowed for minimal damage to the encapsulation structure according to scanning electron microscopy and the hydration properties of powder was improved. This work provides a new idea for using egg yolk to encapsulate DHA and improving the properties of egg yolk powder., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

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., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Preparation of egg yolk powder (EYP) with excellent hydration properties and dissolution stability is important for the efficient utilization of its functional properties and nutritional properties in food. In this work, a new method utilizing ultrasound-assisted enzymolysis (UP-EM) was investigated to obtain EYP. Compared to enzymolysis-alone treated (EM), ultrasonic pre-treatment (UP) significantly increased the enzymatic hydrolysis rate by 106.28%. In particular, the UP 60 W 20 min-EM group obtained the desired solubility and coefficient of stability. The observed microstructure of EYP showed that the egg yolk particles obtained by UP-EM were more uniformly distributed and smaller in particle size. The protein structure was confirmed by Fourier transform infrared spectrum, which showed that UP enhanced the hydrogen bonding force between egg yolk proteins. Therefore, it can be believed that UP-EM can significantly improve the hydration properties and dispersion stability of EYP, laying the foundation for its wide applications in food industry., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

The egg yolk immunoglobulin (IgY) loaded chitosan-liposomes (IgY-CS-LP) were prepared and assisted by supercritical carbon dioxide (SCCO 2 ). The effects of phospholipid type and SCCO 2 pressure on particle size, zeta potential, encapsulation efficiency, structural properties and stabilities were investigated. The results showed that the liposomes prepared by egg yolk phosphatidylcholine (EPC) had better homogeneity and higher encapsulation rate than those by soybean phosphatidylcholine (SPC). With the increase in critical pressure, the particle size decreased dramatically and became more uniform. Under pressure of 20 MPa, it showed a preferable stability on IgY-CS-LP and superior encapsulation efficiency of IgY (76.85%). Besides, IgY could be wrapped in the phospholipid layer which has strong interaction with chitosan. The results suggested that chitosan liposome complex could form an effective carrier for IgY with method of SCCO 2 , which can solve the problem of IgY inactivation in vivo, so as to enhance human immunity and other effects., (Copyright © 2021. Published by Elsevier Ltd.)

The antigen binding fragment (Fab) is pepsin-digested product from egg yolk immunoglobulin (IgY), which shows lower immunogenicity and higher antibacterial activity. However, it limited the application of Fab due to the spontaneous adsorption and aggregation at the air-liquid interface. The present work is to investigate the effect of surfactants polysorbate 20 (PS20), poloxamer 188 (P188), and polyethylene glycol (PEG) on the aggregation stability of Fab of IgY. The results confirmed the positive role of surfactants in improving Fab stability. PS20 could effectively prevent the generation of Fab aggregates (DLS and light-obscuration analysis). It could also distinctly increase the internal hydrophobicity level, fortify the surface charge by altering the molecular conformational characteristics of Fab. The results of CLSM and surface tension demonstrated that P188 and PEG were co-adsorbed with Fab at the air-liquid interface and inhibited the formation of aggregation. PS20 competitively adsorbed in the gap between Fab molecules to inhibit the formation of aggregates. These findings would give an in-depth understanding of protein aggregation behavior influenced by surfactants and provide a theoretical basis for the development of functional food based on Fab active fragments., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The effects of high-intensity ultrasonic (HIU) treatment on the functional properties of egg yolk were studied in the present work. After HIU treatment, the emulsifying, foaming and gel properties of the egg yolk solution significantly increased, but the foam stability decreased. SDS-PAGE results showed that there was no obvious change in the protein bands of egg yolk, indicating that the yolk proteins did not undergo covalent crosslinking or degradation. HIU treatment enhanced the zeta potential of egg yolk components in solution and increased the free sulfhydryl content of egg yolk proteins. Moreover, the particle size distribution of egg yolk components in solution changed markedly, and these changes demonstrated that HIU treatment caused the aggregation of yolk low-density lipoprotein and the partial dissociation of yolk granules. These results revealed that HIU treatment could change the aggregation of yolk components, which in turn could influence the solution characteristics of egg yolk, finally resulting in changes to the functional properties of egg yolk., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Preserved egg, a traditional Chinese egg product, is regarded as an anti-inflammatory food in traditional Chinese medicine. This study was aimed to examine anti-inflammatory effect of the simulated gastrointestinal digestive products of whole preserved egg (DWPE), preserved egg white (DPEW), and preserved egg yolk (DPEY) on lipopolysaccharide (LPS)-stimulated RAW264.7 cells. The results demonstrated that DWPE, DPEW, or DPEY inhibited the LPS-induced secretion of Nitric oxide (NO), without marked cytotoxicity. The DWPE, DPEW, and DPEY significantly suppressed the secretion of pro-inflammatory cytokines, such as tumor necrosis factor (TNF)-α and interleukin (IL)-6. Particularly, the inhibition rate of DPEW on NO, IL-6, and TNF-α could reach 25 to 27%, 31 to 42%, and 26 to 38%, respectively (P < 0.05). Furthermore, the DPEW and DPEY downregulated the gene expression of Cyclooxygenase-2 and inducible nitric oxide synthase in a dose-dependent manner. Taken together, this study indicated that DWPE, DPEW, and DPEY, especially DPEW, might serve as functional food for anti-inflammatory therapy., (© 2019 Poultry Science Association Inc.)

Immunoglobulin Y (IgY) is a new therapeutic antibody that exists in hen egg yolk. It is a glycoprotein, not much is known about its N-glycan structures, site occupancy and site-specific N-glycosylation. In this study, purified protein from hen egg yolk was identified as IgY based on SDS-PAGE and MALDI-TOF/TOF MS. N-glycan was released from IgY using peptide-N4-(N-acetyl-beta-glucosaminyl) asparagine-amidase treatment, and the molecular weight of IgY was calculated using the difference between the molecular weight of IgY and deglycosylated IgY. Two potential N-Glycosylation sites (ASN 308 and ASN 409 ) were detected on IgY by nanoLC-ESI MS. Sugar chains were separated using normal phase liquid chromatography after fluorescence labeling, and 17 N-glycan structures were confirmed using ESI-MS. The sugar chain pattern contained high-mannose oligosaccharide, hybrid oligosaccharide and complex oligosaccharide. These results could lead to other important information regarding IgY glycosylation., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Immunoglobulin Y (IgY) is a new therapeutic antibody, and its applications in industry are very broad. To provide insight into the effects of N-glycosylation on IgY, its conformation and stability were studied. In this research, IgY was extracted from egg yolk and then digested by peptide-N4-(N-acetyl-beta-glucosaminyl) asparagine-amidase. SDS-PAGE and infrared absorption spectrum showed that carbohydrates were distinctly reduced after enzymolysis. The circular dichroism spectrum indicated that the IgY molecule became more flexible and disordered after removal of N-glycan. The fluorescence intensity revealed that Trp residues were buried in a more hydrophobic environment after disposal of N-glycan. Storage stability decreased with the removal of oligosaccharide chains based on size-exclusion chromatography analysis. Deglycosylated IgY exhibited less resistance to guanidine hydrochloride-induced unfolding. After deglycosylation, IgY was more sensitive to pepsin. Therefore, N-glycosylation played an important role in the maintenance of the structure and stability of IgY., (Copyright © 2016 Elsevier B.V. All rights reserved.)

An economical, effective and large-scale method for the preparation of immunoglobulin of chicken egg yolk (IgY) was developed. The method was based on an improved water dilution combining with polyethylene glycol 6000 (PEG6000) precipitation and anion-exchange chromatography. The egg yolk was diluted with 8 volumes of aseptic water, the pH of which was adjusted to 5.2 with 0.1 mol/L HCl, then the mixture was centrifuged at 5 000 x g after standing for 8 h at 4 degrees C. The crude IgY was obtained from the supernatant layer with the yield of 93.47%. The purification of IgY was achieved by 6% PEG6000 precipitation and DEAE-Toyo-pearl 650 M anion-exchange chromatographic packing. The optimum purified conditions by ion-exchange chromatography were as follows: equilibration with 0.05 mol/L phosphate buffer (pH 7.0) and elution with 0. 075 mol/L phosphate buffer (pH 7.0). The purity of the IgY fraction was consistently greater than 95% with high activity (73.77%) by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). This method is superior to the traditional ion-exchange chromatography that can't simultaneously obtain high purity and high recovery. Moreover, this method is suitable for a large-scale IgY preparation from chicken egg yolk.

Due to the poor aqueous solubility of docosahexaenoic acid (DHA), encapsulating it in egg yolk results in a reduction in the hydration properties of egg yolk powder (EYP), subsequently affecting its functional properties. In this study, the effects of vacuum low-temperature spray drying (VLTSD), high-temperature spray drying (HTSD), and freeze-drying (FD) on the hydration properties of DHA-enriched EYP were investigated. Firstly, we optimized the inlet temperature and feed rate for VLTSD (60 °C, 300 mL/h) and HTSD (170 °C, 800 mL/h), while FD was conducted under − 70 °C conditions. The most striking finding of this study was the DHA-enriched EYP prepared by VLTSD exhibited desirable solubility (54.86 g/100 g), water dispersibility (48.63%), and coefficient of stability (24.88%) during rehydration, which was well predicted by low-field NMR. Compared to HTSD and FD, the solubility increased by 16.18% and 45.17%, respectively. Furthermore, at the microscopic level, SEM images and FTIR spectra revealed that VLTSD enhanced the hydration properties by protecting the structural integrity and increasing the hydrogen bonding of the DHA-enriched EYP. The encapsulation efficiency of DHA-enriched EYP prepared by VLTSD, HTSD, and FD were 97.15%, 96.51%, and 81.31%, respectively. According to the quality analysis, VLTSD had the best protection for DHA-enriched EYP in terms of chromaticity, bulk density, storage stability, and sensory evaluation. Therefore, this study confirmed the applicability of VLTSD technology for microencapsulation of bioactive substances such as DHA to enhance the hydration properties of powders. [ABSTRACT FROM AUTHOR]

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]

Pickering high internal phase emulsions (HIPEs) are gel-like concentrated emulsions that have the potential to be an alternative to partially hydrogenated oil (PHO). In this study, egg yolk granules (EYGs), natural complexes of protein and lipid isolated from egg yolk, were used as an emulsifier to prepare Pickering HIPEs. Gel-like HIPEs with an oil phase volume fraction of 85% and with an emulsifier concentration of only 0.5% could be prepared by using EYGs as an emulsifier. The EYGs were able to form stable HIPEs at NaCl ionic strengths over 0.2 M and at pH over 5.0 with NaCl ionic strength of 0.3 M. The EYGs, which could stabilize HIPEs, were easily to adsorb and cover the oil-water interface to form emulsion droplets with small particle size. In addition, interacting EYGs in the aqueous phase formed a continuous network structure, and the oil droplets packed closely, exhibiting high elasticity and shear thinning behavior. Furthermore, the formed HIPEs had suitable storage stability with no significant changes in appearance and microstructure after storage for 60 days. This work can transform traditional oils from liquid-like to solid-like by using EYGs to enrich food processing diversity and improve the storage stability of oils while reducing the intake of PHO and providing a healthier diet for consumers. [ABSTRACT FROM AUTHOR]

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]

Egg yolk powder (EYP) is widely used in food processing due to its excellent emulsifying properties, but its poor solubility limits its market application as a powdered beverage. In this study, papain, trypsin, and subtilisin were used to hydrolyze egg yolk, and the effects of enzymatic hydrolysis on the solubility of EYP was investigated. The results showed that subtilisin treatment significantly improved the water dispersibility, powder solubility and stability coefficient of EYP (P < 0.05) by 41.67%, 98.16%, and 66.21%, respectively, while its solubility did not change significantly after the treatment with papain and trypsin. The degree of hydrolysis (DH) was related to the enzyme active site and the treatment with papain and subtilisin resulted in a higher DH. Additionally, the results of sodium dodecyl sulfate-polyacrylamide gel electrophoresis, particle size distribution and scanning electron microscopy proved that the molecular weight of subtilisin-treated EYP was lower than EYP after the other treatments. Moreover, surface hydrophobicity and zeta-potential results indicated that molecular hydrophobicity and the amount of surface charge increased after enzymatic hydrolysis. The hydratability of papain-treated EYP increased to 20.91%. Low-field nuclear magnetic resonance results showed that enzymatic hydrolysis changed the content of bound water in the EYP, resulting in the changes of its ability to combine with water. • Three hydrolyze proteases enzymes can affect the yolk solubility. • Subtilisin treatment significantly improved the solubility of egg yolk powder. • Papain and trypsin treatment did not significantly change the solubility. • The different effects due to the difference in the hydrolysis site of the enzyme. • Hydrophobic groups combined with lipoproteins can reduce the surface hydrophobicity. [ABSTRACT FROM AUTHOR]

Organogels have emerged as potential alternatives to trans and saturated fats. We developed semi-solid stable organogels using egg yolk granules-chitosan complex (EYGs-CS). We investigated the impacts of pH and NaCl ionic strength on the structural, rheological, and stability characteristics of the organogels. We found that stable organogels formed under acidic pHs (≤ 5.0) and high ionic strengths (≥ 0.2 M), displaying small droplet sizes, excellent elasticity behavior, poor oil migration, and high stability. The efficient adsorption of EYGs-CS at the oil surfaces formed stable droplets with compact walls. A colloidal 3D-network was formed within the aqueous phase, resulting in elastic and firm organogels. The droplets under acidic conditions showed higher surface charges, which blocked their coalescence through the electrostatic repulsion. The electrostatic shielding at high ionic strengths caused high steric repulsion, resulting in higher stability. This work provides insight into the replacement of harmful fats with healthier alternatives. [Display omitted] • Egg yolk granules-chitosan forms organogels as alternatives to trans/saturated fats. • Acidic pH and high ionic strength foster stable EYGs-CS-based organogels. • Efficient EYGs-CS adsorption forms stable tiny droplets with compact films. • A 3D-network forms, yielding elastic, firm organogels, limiting droplet migration. • Electrostatic and steric repulsions hinder droplet coalescence, enhancing stability. [ABSTRACT FROM AUTHOR]

Yolk immunoglobulin (IgY) is an excellent complement or substitute for mammalian immune globulin G, whose development is severely limited for its difficult isolation and purification. This work provides a combination technique for the large-scale isolation of IgY products with different purity levels to meet the market demand. Four levels (IgY-I to IgY-IV) of IgY products were sequentially separated and purified using water dilution, high-speed-shear crossflow membrane separation, and two-step salting out methods, during which the key limiting factors were optimized through the single factor tests. The IgY-I, with purity and yield of 30.69% and 25.06 mg/mL yolk, met the general demand for immune-fortified food for pets. IgY-II and IgY-III achieved purity of 35.84% and 66.09%, yielding 21.76 and 13.92 mg/mL yolk, respectively. Notably, the purity (96.9%) and yield (6.06 mg/mL yolk) of IgY-IV approximated or even exceeded the level of IgY isolated by IgY purification kits, and its purity was higher than that of the commercially available IgY standards. During the isolation, traditional centrifugation and filtration were replaced by continuous flow centrifugation and high-speed-shear crossflow membrane separation for continuous sample loading and sample concentration (a concentration factor of 85.37%). This is of great significance to shortening processing time, saving costs, and meeting needs of large-scale production. This technique has the advantages of high efficiency, low energy consumption, low cost, environmentally friendly, and friendly to human health by supplying IgY products with different purity levels to meet the market demands and promote the development of IgY-related industries. [Display omitted] • A method was developed for large-scale isolation of yolk immunoglobulin (IgY). • A batch of yolks (5 L) were processed continuously to obtain 4 levels of IgY. • Level II IgY achieves purity of 35.84%, yield of 21.76 mg/(mL yolk). • Level III IgY achieves purity of 66.09%, yield of 13.92 mg/(mL yolk). • Purity (96.9%) of level IV IgY higher than that of the available IgY standard. [ABSTRACT FROM AUTHOR]

The immunoglobulins, most of them are glycoprotein, play an important role on humoral immune. We herein report a triple-modenano sensor with a fluorometric readout based on CdTe quantum dots (QDs) and gold nanoparticles (AuNPs) for discriminative detection of immunoglobulin. Immunoglobulins fall into several classes, each with its own functional characteristics. In this research, we use chicken egg yolk immunoglobulin (IgY) as an example to establish the specific detection methods. IgY is the only antibody existing in chicken egg yolk, which has many significant advantages. We used anti-IgY and staphylococcal protein A (SPA) to make the detection discriminatively to IgY. The immune interaction between QDs-SPA and anti-IgY-AuNPs leads to drastic quenching (turning off) of the donor by a fluorescence resonance energy transfer (FRET) process. After the addition of IgY, anti-IgY-AuNPs peel off from the QDs-SPA surface and bind to IgY due to competitive immunoreactions, resulting in the restoration of the fluorescence intensity of QDs (turning on). Consequently, this process can be utilized for the selective detection of IgY via optical responses. This proposed assay demonstrated a favorable anti interference ability and highly selectivity toward IgY with a detection limit of 1.16 ng/mL. More importantly, the nanosensor could not only function in aqueous solution for IgY detection with high sensitivity but also exhibit sensitive responses toward IgY in complicated biological environments, demonstrating its potential in bioanalysis, which might be significant in biochemical field in the future. [ABSTRACT FROM AUTHOR]

Chicken egg yolk immunoglobulin (IgY) is a superior alternative to mammalian immunoglobulin. However, the practical application of IgY in research, diagnostics, and functional food is limited due to complex or time-consuming purification procedures. The objective of this study was to develop a simple, safe, large-scale separation method for IgY from egg yolk. Egg yolk was diluted with 6-fold delipidation solutions made of different types (pectin, λ-carrageenan, carboxymethylcellulose, methylcellulose, and dextran sulfate) and concentrations (0.01, 0.05, 0.1, 0.15, and 0.2%) of polysaccharides, respectively. The yolk solution was adjusted to pH 5.0, and then kept overnight at 4°C before being centrifuged at 4°C. The resulting supernatant was added to 35% (w/v) (NH4)2SO4 and then centrifuged. The precipitant, which contained IgY, was dissolved in distilled water and then dialyzed. SDS-PAGE and Western blotting were utilized to conduct qualitative analysis of IgY; high-performance liquid chromatography (HPLC) was used for quantitative analysis. The immunoreactivity of IgY was measured by ELISA. The results showed that yield, purity, and immunoreactivity varied with types and concentrations of polysaccharides. The optimal isolation of IgY for pectin, λ-carrageenan, dextran sulfate, and carboxymethylcellulose was at the concentration of 0.1%; for methylcellulose, optimal isolation was at 0.15%. The best results were obtained in the presence of 0.1% pectin. In this condition, yield and purity can reach 8.36 mg/mL egg yolk and 83.3%, respectively, and the negative effect of IgY on immunoreactivity can be minimized. The procedure of isolation was simplified to 2 steps with a higher yield of IgY, avoiding energy- and time-consuming methods. Therefore, the isolation condition under study has a great potential for food industry production of IgY on a large scale. [ABSTRACT FROM AUTHOR]

The plasma, which is an effective contributor to the emulsifying properties of egg yolk, could offer new pathways in emulsification technology. This study investigated the influence of cationic guar gum (CGG) and oleic acid (OA) on the emulsion stability of the subtilisin-hydrolyzed natural plasma (NP). The results showed that the enzyme-hydrolyzed plasma (EP) contributed to the higher ζ-potential, smaller D [4,3] and lower initial interface tension of the droplets than the NP, which improved emulsion stability. The enzymatic hydrolysis of plasma enhanced the electrostatic repulsions of the droplets and accelerated the adsorption of proteins at the interface. As the addition of CGG increased from 0.020% to 0.040% (w/v), the EP droplets with higher ζ-potential and smaller D [4,3] were formed because of the interactions between the interface membrane. The addition of CGG at 0.030% (w/v) significantly increased the emulsifying stability index of the EP (from 22.9 to 55.4). After 375 min of holding, the cream layer decreased from 68% to 58% when 0.040% (w/v) CGG and 1% (v/v) OA were added to the emulsion. These results confirmed that the EP with CGG and OA enhanced the viscosity and the weak-gel structure, which improved the stability of the emulsion. Image 1 • The emulsifying properties of egg yolk plasma were modified by subtilisin. • The CGG and OA facilitate to improve the emulsions stablility. • Higher CGG concentration could increase stability of emulsions. • OA as a co-emulsifier could construct bilayer emulsion membrane. [ABSTRACT FROM AUTHOR]

Egg yolk granules (EYG) are natural and unique protein-lipid complexes, but their application in the food industry is limited because of their poor solubility and emulsifying properties. In this paper, the structural characteristics, emulsifying properties and interfacial adsorption were compared between the untreated granules (UG) and the enzymatically hydrolyzed granules (EG) (treated with subtilisin). EG-stabilized emulsion did not form cream at 0.2%–1.0% protein concentrations, while UG-stabilized emulsion formed a cream layer quickly after emulsification. The emulsion stability index of EG increased by nearly 8 times increased from 0.2% to 1.0%. The scanning electron microscope, confocal laser scanning microscopy (CLSM) and optical microscopy indicated that enzymatic hydrolysis changed the aggregation state of the EYG in powder, suspension and emulsions. Also, it was proven that enzymatic hydrolysis strengthened the internal hydrogen bonding and increased surface wettability and surface charge. The CLSM images confirmed that EYG are Pickering particles. The interfacial tension dropped to 8.4 mN/m after enzymatic hydrolysis. The SDS-PAGE analysis of the protein showed that enzymatic hydrolysis induced changes in the granules and interface, resulting in a strong adsorption capacity for EG at the interface. The enzymatic modifications of EYG promoted their emulsifying properties and showed that EYG have the potential to be used as novel food-grade particles through structural modification. Image 1 • Egg yolk granules (EYG) were enzymatically modified and structurally analyzed. • The aggregation states were imaged by SEM, CLSM and OM. • The protein composition of EYG and the interface was measured by SDS-PAGE. • Hydrogen bonding was enhanced and the wettability and charge were increased after hydrolysis. [ABSTRACT FROM AUTHOR]