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In this paper, the interaction between egg white protein (EWP) and giant squid surimi was regulated by changing the ratio of surimi to EWP, and the mechanism of EWP on the gel properties of giant squid surimi was analyzed. The results showed that when the proportion of EWP was 16: 1, the hardness and springiness of surimi gel were the highest, reaching 645.5 g and 1.258, respectively. The gel strength reached 0.634 kg, the cooking yield of surimi gel increased by 27 % and the water loss decreased to less than 10 %. A significant increase in the proportion of fixed water and a decrease in the proportion of free water indicated that mixed surimi improved the "trapping" ability of water molecules, induced the formation of a more ordered "cage"-like structure, and significantly increased the water holding capacity and whiteness of surimi gels. [Display omitted] • Low levels of EWP improved strength, cooking rate and water holding ability of gel. • EWP increased the contribution of ionic bond and hydrophobic force in surimi gel. • EWP inhibit the rapid aggregation of MP and induce to form orderly cage structure. • Excess EWP (at surimi: EWP of 8:1) cause the loose crosslinking of EWP and surimi. • Adjusting the interaction of EWP and surimi can produce gels with various property. [ABSTRACT FROM AUTHOR]

This study investigated the potential of egg white protein (EWP) to be developed into a kind of Pickering stabilizer for oil-in-water emulsions. The EWP microparticles were formed by heating at 90 °C for 45 min, followed by homogenization under low pressure. The characteristics and microstructure of microparticles prepared under various pH (3.0, 3.8) and protein concentration (2–10%) were tested. Simultaneously, the properties of Pickering emulsions integrated by EWP microparticles, with fibrous or granular morphology, were investigated. At pH 3.0, the particles may transfer from fibrous structure to granular structure with protein concentration increased or salt addition. At pH 3.8, granular microparticles were formed under various protein concentration. The structure of EWP microparticles were mainly maintained by hydrophobic interactions and hydrogen bondings. The granular particles showed higher surface loading of protein and viscoelastic moduli in the integrated Pickering emulsions. These results have important implications for the formulation and production of emulsion based semi-solid products, using egg white protein as emulsifier and fat substitute. [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 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]

Abstract: The promotion or inhibition of gastrointestinal digestion of tea polyphenol (TP) towards the two typical proteins from egg white (ovalbumin (OVA) and lysozyme (LYZ)) was examined. The results showed that TP made OVA/LYZ easier for digestion in the pepsin solution at pH1.2 and inhibited OVA/LYZ digestion in pancreatin solution at pH7.5. Non-covalent interactions between OVA/LYZ and TP and the secondary structure of OVA/LYZ were studied by using Fluorescence spectroscopy and Fourier transform infrared spectroscopy (FTIR), respectively. Results suggested that stronger conformational change occurred at pH1.2 compared with that of pH7.5 affected by TP in both proteins. Non-covalent interactions between OVA/LYZ and TP at pH1.2 increased random and β-sheet structures in both proteins at the expense of α-helix, which resulted in the proteins with looser structures. At pH7.5, an opposite second structural change of both proteins caused by the non-covalent interactions between OVA/LYZ and TP. The conformational and second structural change of proteins (substrate) might be a reason for promoting and inhibiting digestion of OVA/LYZ affected by TP. [Copyright &y& Elsevier]

OVA (ovalbumin)/CMC (sodium carboxymethylcellulose) nanoparticles are prepared by combining complex coacervation and thermal induction. The effect of different parameters on stability of OVA/CMC nanoparticles (different ratios, pH, temperature, salt concentration and storage time) is investigated. And then the loading and stabilizing mechanism of particles on curcumin are further analyzed. After heating, OVA and CMC in particle could further cross-linking and a highly salt-tolerant and ultra-long stable nanoparticle can be formed. OVA/CMC nanoparticle with the loose structure of wool ball could effectively load curcumin with the loading content and loading efficiency of 36.40 and 95.40%, 36.30 and 92.82%, 36.0 and 94.48% for the ratios of 1:2, 1:1 and 2:1, respectively. Curcumin-loaded of OVA/CMC nanoparticles show good DPPH· scavenging activity, Ferric-reducing ability and ABTS+ scavenging activity compared with curcumin/water. The results can be useful for designing food and beverage particle with improving bioactive substances functional properties. • OVA/CMC nanoparticles were prepared by combining complex coacervation and thermal induction. • Nanoparticles showed ultra-long stability and high salt concentration tolerance. • OVA/CMC nanoparticles with concave/convex structure exhibited good curcumin load capacity. • Curcumin-loaded nanoparticles showed and improved antioxidant activity than free curcumin in water. [ABSTRACT FROM AUTHOR]

Egg white protein is a kind of protein resource with distinctive nutritional value and functional properties, while performing weak emulsifying stability under neutral and alkaline conditions, limiting application in food industry. This study, we investigated the effect of enzyme on characteristics of egg white protein (EWP) and synergistic efficiency of pectin addition on properties (thermal stability, salt resistance and antioxidant activity) of emulsions stabilized by original or hydrolyzed EWP. The EWP solutions were incubated at pH 7.0, under 50 °C for 2 h, with various amount of enzyme (0%, 0.5%, 1%, 2%, and 4%) added in. With enzyme concentration increased, more ovotransferrin and ovalbumin were hydrolyzed, and more hydrophobic amino acids exposed to polar environment, especially tyrosine. In addition, the DPPH and ABTS radical scavenging activity of EWP increased with enzyme concentration increased. Pectin addition can effectively improve the stabilization of the emulsion droplets, inducing smaller effective diameter and polydispersity index. In comparison, the emulsions stabilized by hydrolyzed EWP with 0.3% pectin behaved better thermal and salty stability, while with poorer antioxidant capacity attributed to weaker intermolecular interactions. The rheological measurement showed that the viscosity of hydrolyzed EWP stabilized emulsion was relatively lower and G′ was more dependent on frequency, indicating weaker cross-links among droplets. The results may provide theoretical guidance for application of enzymatic and polysaccharide blends in improving protein functionality. [ABSTRACT FROM AUTHOR]