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The gel properties and secondary structures of soybean protein isolate/egg white composite gels with different blend ratios and protein concentrations were investigated in this paper. The hardness, springiness and water-holding capacity of composite gels were all increased with the increase in the protein concentrations. When total protein concentration was above 0.03 g mL, the soybean protein isolate/egg white proteins blended in ratio of 1:1 showed higher enhancement in springiness and water-holding capacity. The hardness and storage modulus of gels increased gradually with the increase in egg white in the composite gels. The content of α-helical structures of the gels were increased firstly and then decreased, whereas the content of β-sheet was increased gradually with the increase in egg white ratio. The tendencies of α-helical and β-sheet were in accordance with springiness and hardness of gels, respectively. The microstructure investigations showed that gels formed an even structure with less large particles at the soybean protein isolate/egg white ratio of 1:1, which was related to the higher springiness and water-holding capacity. The relationship between changes in the protein structure and the texture properties could be used to design product systems. [ABSTRACT FROM AUTHOR]

Highlights • The particle size of EWP nanoparticle increased with addition of curcumin solution. • Ethanol would induce more α-helix transferred to β-sheet during heating treatment. • At pH 3.0, EWP behaved higher loading efficiency than pH 3.8. • EWP nanoparticle can effectively slow down curcumin degradation rate. Abstract This study investigated the encapsulation of curcumin into egg white protein (EWP) nanoparticles. Processing conditions used to formulate the nanoparticles, including pH and the addition of ethanol, were used to control the unfolding and aggregation behavior of EWP. The curcumin loading capacity of the EWP nanoparticles was found to be strongly linked to the structural transitions of the protein during heat denaturation, and the microscopic properties of the particles such as particle size and zeta-potential. Fibrous particles were formed at lower pH (3.0) and were associated with a higher curcumin loading than the granular particles formed at pH 3.8. Ethanol leads to an increase in β-sheet structure, and the formation of a coarser gel structure during heat denaturation, resulted in an increase in particle diameter. The highest curcumin loading capacities were 11.53 and 9.89 mg/g protein (with a final curcumin concentration of 312.5 μM and 268 μM respectively), at pH 3.0 and 3.8, respectively. Encapsulation in EWP nanoparticles was shown to both effectively slow the degradation ratio as well as protect the antioxidant activity of encapsulated curcumin. [ABSTRACT FROM AUTHOR]

This study investigated the influence of acid (pH 3.0) or moderate heat (60 °C, 15 min, pH 3.0) treatments on physicochemical characteristics (ζ-potential and hydrophobicity), structure (Raman spectra) and emulsifying capacity of EWP after re-adjusted to various pH. Simultaneously, the stability of the emulsions prepared with acid and acid-heat induced EWP (AEP and AHEP) was tested by measuring particle diameter and microstructure of the droplets after salt (0–200 mM NaCl) and heat (90 °C, 30 min) treatments at pH 3.0–4.2. The results revealed that the emulsifying capacity of EWP was enhanced after acid or acid-heat treatment with more hydrophobic amino acids and charged groups exposed on the surface, but little changes in secondary structure. Proteins adsorbed at the oil-water interface were mainly ovotransferrin and ovalbumin. The emulsions made with AEP and AHEP were stable to droplet aggregation with no phase separation during storage for 3 weeks at pH below isoelectric point (pI ≈ 5.0), but exhibited some aggregation at pH near or above pI. The heat stability of emulsions depended on pH and thermal history. The emulsions made with AHEP performed better heat stability than AEP-stabilized emulsions. The salt stability of emulsions depended on the net charge. At pH 3.0, the emulsions were stable in the presence of ≤100 mM NaCl. At other pH, the emulsions showed good tolerance to 50 mM NaCl. These results have important implications for the formulation and production of emulsion based acid products, using egg white protein as emulsifier. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the influence of selected saccharides (glucose, sucrose, and maltodextrin) on the foam characteristic of egg white liquid. The rheological measurements suggested that increasing sugar concentrations in egg white led to an increase in both apparent viscosity and viscoelasticity. Moreover, the addition of saccharides shortened the relaxation time of hydrogen proton, indicating the presence of hydration effect between sugar and water. Samples with 3% saccharides increased the surface hydrophobicity and reduced the surface tension of the compound egg white solution, leading to the increase of foam capacity and stability. The best foam performance of compound egg white solution was achieved when the 3% maltodextrin was present in egg white, along with the smallest and most homogeneous bubbles. The classification of mixture conditions by the principal component analysis (PCA) and cluster analysis (HCA) revealed that the maltodextrin-egg white system had good scores both at 0.6% and 3% adding ratios, indicating maltodextrin is a suitable additive for the modification of egg white foam properties. [Display omitted] • Saccharides improved both the foam capacity and stability of egg white. • Maltodextrin is a suitable additive for modification of egg white foam properties. • Saccharides improved rheological properties of egg white by changing water sate. • Quantitative associations between foam and physicochemical indexes were studied. [ABSTRACT FROM AUTHOR]

Non-meat proteins are widely used in the meat processing, and the final product is greatly affected by salt. This study presented the combined use of soybean protein isolate (SPI) and egg white (EW) on the gelation of chicken myofibrillar protein (MP) with or with NaCl. Gel properties were determined with the use of texture profile analysis, cooking loss, intermolecular forces, rheological properties, scanning electron microscopy and low field nuclear magnetic resonance (LF-NMR) measurements. Non-meat proteins improved the MP gel quality when it was without NaCl, except for the increased cooking loss caused by 1.2% SPI. The effect of non-meat proteins on MP gel quality was more obvious at 0.3 mol/L NaCl, including the improvement of gel hardness by SPI and the reduction of cooking loss by EW. When the added non-meat proteins changed from 1.2% SPI to 0.3% EW-0.9% SPI, the gel hardness significantly decreased (P < 0.05). Its storage modulus was even lower than that of the pure MP, and uneven protein aggregates and pores were observed in the microstructure. This was because the SPI aggregates were wrapped by EW, and the SPI-EW aggregates led to the local aggregation of MP and the uneven structure of MP gel. • Soybean protein isolates (SPI) were wrapped by egg white (EW) forming aggregates. • The SPI-EW aggregates caused the local aggregation of myofibrillar protein (MP). • The combined utilization of SPI and EW improved the MP gel quality. [ABSTRACT FROM AUTHOR]

Abstract The foaming characteristics (foam ability, foam stability and foam microstructure) of fresh foams based on egg white protein, and with the addition of different proportions of egg yolk and yolk fractions (plasma and granules) were analyzed in this research. The relationships between foaming properties and addition of yolk fractions were carried out via surface tension, surface hydrophobicity, apparent viscosity and zeta potential. The results showed that charge properties of yolk fraction dispersions were considered to have positive correlations with their foam stability to egg white. The foam abilities might possibly be determined by their particular structure and interactions with egg white protein. Besides, their interactions could also be represented by surface tension and surface hydrophobicity. Therefore, this study provides a new insight for determining the relationship between foaming properties of egg white contaminated by proportions of egg yolk fractions and the physicochemical properties of egg white/yolk or yolk fractions dispersions. Graphical abstract Image 1 Highlights • Foaming properties of egg white-yolk/fractions were studied. • Components and Structures in yolk/fractions influenced foaming characterization. • Surface indexes dominated foam properties of egg white-yolk/fractions dispersions. • Surface charge resulted in high foam stability of egg white/granules bubbles. [ABSTRACT FROM AUTHOR]

Abstract Egg gel is the combined gelation of egg white (EW) and egg yolk (EY); its properties depend on the fixed ratio of EW and EY in shell egg. This study investigated the gelation properties of egg mixtures in artificial blends to explore innovative egg solutions catering to the market demands and provide guidance for the production of creative egg products. Results showed that solubility of samples decreased with the increase of EY proportion while solid content increased. More surface hydrophobicity and total SH group increases were observed with higher EY proportion. Rheological tests suggested that adding EY decreased samples' initial G' values. Egg gel containing 20% EY presented the largest hardness value, which seems to be related to the fine gel network microstructure. Besides, the springiness and water-holding capacity of gels gradually increased with EY addition, which may be the result of dense microstructure and high solid content of EY. Highlights • Gelling properties of egg white and yolk were dependent on the proteins. • Water-holding capacity of egg gels was closely related to gels' microstructure. • Yolk filled the cavities existing in egg white gels, making microstructure denser. [ABSTRACT FROM AUTHOR]

The effects of NaOH and NaCl on the rheology and gel properties of hen egg white were investigated. As the concentration of NaOH increased, egg white gel exhibited lower opacity and particle turbidity with coincidental increase in zeta potential, while the addition of NaCl resulted in the formation of opaque egg white gel and increase of surface hydrophobicity, particle turbidity and zeta potential. Rheological tests showed that alkali treatment will affect the unfolding state of egg white proteins during the heat stage while NaCl addition can inhibit the unfolding of egg white proteins. The results of correlation analysis indicated that random coil and α-helix were in good correlation with gel textural properties. Therefore, the rheology and gel properties of alkali/salt-induced egg white dispersions were closely related to the changes in surface hydrophobicity, molecule surface charge, and protein secondary structure. [ABSTRACT FROM AUTHOR]

The effects of NaCl addition on the gelling and water holding properties of egg white/yolk gels were studied via solubility, surface hydrophobicity, reduced sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), Fourier transform infrared spectra (FTIR), textural analysis, low-field nuclear magnetic resonance (LF-NMR) and centrifugation. Results showed that more solubility and surface hydrophobicity increase of egg yolk dispersions were observed than that of egg white dispersions. SDS-PAGE results indicated that the different change trend of surface hydrophobicity between two egg proteins was closely related with the dissociation of egg yolk granule proteins. NaCl-induced protein heat denaturation will result in the decrease of ordered secondary structure (α-helix and β-sheet) by breaking hydrogen bond for both egg protein gels. A rapid decrease ( p < 0.05) in fracture strength/strain of egg white gels was found as the NaCl increased, while the fracture strength/strain of egg yolk gels first rose and then descended, indicating that the significant increases of solubility and hydrophobicity of egg yolk dispersions at a certain NaCl concentration (≤1.8%) were benefit to the formation of strong molecule interaction among gel network. Results from LF-NMR and centrifugation water holding capacity (WHC) tests revealed that NaCl addition affected the WHC of egg white gels by increasing the mobility and distribution of free water, and had a complex influence on proton mobility and relaxation peak changeability of egg yolk gels due to the interaction among lipid, protein and water. [ABSTRACT FROM AUTHOR]

In order to improve the nutritional and gelling properties of soy protein isolate (SPI) gel system, potato protein (PP), egg white (EW) and PP-EW mixtures were added. The texture properties, intermolecular forces, and secondary structures of the gels were examined. Then the microstructure observation, rheological measurement and digestibility assay were conducted. The results showed that the gel of 3PP-3EW had the highest proportion of β -sheet (47.04%), the most ordered gel structure, and the highest proportion of immobilized water (96.03%). The digestibility of SPI-PP-EW gels was higher than that of SPI-PP gel or SPI-EW gel. With the increase of EW proportion, the gel hardness increased along with the increased proportion of covalent bonds. This study is conducive to the development of meat analogues with better amino acid pattern. [Display omitted] • Potato protein (PP) filled in soy protein isolate (SPI) gel in an aggregate form. • Egg white (EW) filled in the SPI gel in the form of aggregate or gel. • The gel of 3PP-3EW had the most β -sheet and the most ordered microstructure. • The digestibility of SPI-PP-EW gel was higher than that of SPI-PP or SPI-EW gel. • The texture properties were regulated by adjusting the addition ratio of PP/EW. [ABSTRACT FROM AUTHOR]