Search

BACKGROUND: Water‐in‐oil‐in‐water (W1/O/W2) emulsions stabilized by protein–carbohydrate complexes were prepared from an inner water phase (W1), an oil phase (O) and an outer water phase (W2). The complexes consisted of heat‐induced aggregates (HIAs) of isomalto‐oligosaccharide/egg white protein Maillard conjugates. The effects of polyglycerol ester of polyricinoleic acid (PGPR) concentration, HIA concentration, W1‐to‐O volume ratio and W1/O‐to‐W2 volume ratio on the properties of the W1/O/W2 emulsions were systematically investigated. RESULTS: At sufficiently high PGPR concentrations (>2%), the emulsions possess a high negative charge (≈−44 mV). The encapsulation efficiency of the emulsions, which was determined by incorporating a hydrophilic yellow dye in the inner water phase prior to homogenization, was relatively high (up to 93%) and did not change significantly during 14‐day storage at 4 °C. All emulsions were fluids that exhibited shear thinning behavior. CONCLUSION: Overall, this study shows that nature‐derived emulsifiers can be used to create W1/O/W2 emulsions suitable for application in the food industry. In addition, we provided a viable strategy to encapsulate water‐soluble nutrients. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

[Display omitted] • Innovative use of egg white powder as a raw material to prepare low Phe peptides. • Shearing after pre-heating greatly improved the hydrolysis of egg white protein. • Trypsin combined with flavoenzyme can best release phenylalanine. • More than 97 % of phenylalanine in egg white protein was removed. Individuals suffering from phenylketonuria require foods containing low levels of phenylalanine (Phe). In this research, we therefore developed a two-step enzymatic hydrolysis method followed by activated carbon treatment to remove Phe from egg white powder (EWP). Nine proteases were tested for their ability to expose or release Phe residues from the egg proteins, while nine kinds of activated carbon were tested as an adsorptive medium for removing Phe residues. Our results showed that trypsin combined with flavourzyme released the most Phe residues, and No.4 activated carbon was most effective at removing Phe residues. The percentage of Phe removal varied from 91.71–97.78% and the final mass yield from 230.08–342.45 g low Phe peptide (LPP) / Kg of EWP. The LPP mixtures obtained mainly containing amino acids and oligopeptides (< 600 Da). The EWP-LPP mixture obtained therefore has the potential to prepare medical foods for patients with phenylketonuria. [ABSTRACT FROM AUTHOR]

Summary: High internal phase emulsions (HIPEs) are potential carriers of fat‐soluble nutrients due to their high loading capacity. In this study, egg white protein particles (EWPP) and rhamnolipid (Rha) were used to co‐emulsify oil/water HIPEs to carry curcumin (Cur). The results showed that the Cur loading efficiency, microstructure, protein composition, molecular distribution of protein hydrolysates, protein interfacial adsorption rate and Cur bioavailability were measured. The results showed that, incorporation with Rha was unhelpful for improving loading efficiency of Cur, which decreased from 80.8% to 73.7% at pH 3.8 after incorporation with Rha, due to the decreased viscosity and destroyed continuous interface membrane, while beneficial for restricting coalescence of oil droplets. As studied, Rha could effectively reduce the droplet size to slow down the speed of coalescence and form EWPP–Rha complex to inhibit proteolysis. Finally, Cur bioavailability in EWPP–Rha co‐emulsified HIPE was the highest (40.3%), indicating the synergistic effect of EWPP and Rha promoting the effective adsorption of Cur, related to the increased coalescence stability during digestion and participation of Rha in the micellisation reaction. In comparison, fibrous (pH 3.8) and granular (pH 7.0) EWPP stabilised HIPEs, showed no obvious difference in Cur bioavailability, due to the balance between the interfacial adsorption ability and the digestion resistance of EWPP with various morphologies. This study has important significance for the construction of lipid soluble nutrient 'carriers' with high load and high bioavailability. [ABSTRACT FROM AUTHOR]

Edible alginate microgels are widely used to encapsulate, retain, protect, and release bioactive molecules in foods. Encapsulation of food proteins within alginate microgels may be advantageous for certain applications, such as creating controlled release delivery systems or for protection of other co-encapsulated bioactive components. Egg white protein-loaded alginate microgels were fabricated in this study using a simple injection-gelation method. The impact of pH (pH 3, 5 and 7) and thermal treatment (25 to 85 °C) on the encapsulation efficiency, retention, and physicochemical properties of the microgels was measured. Protein encapsulation efficiency and retention was highest at the lowest pH, which was attributed to the strong electrostatic attraction between the cationic egg white proteins and anionic alginate. Thermal treatment of the egg white proteins before microgel formation enhanced their encapsulation and retention, which was attributed to an increase in their physical dimensions due to unfolding and aggregation. As a result, it was more difficult for them to diffuse through the pores in the alginate microgels. The information obtained in this study may facilitate the design of more effective protein-loaded alginate microgels for food and other applications. Unlabelled Image • Egg white protein-loaded alginate microgel was fabricated using injection method. • Egg white protein encapsulation efficiency was highest at the lowest studied pH. • Protein retention increased and protein release decreased with decreasing pH. • Thermal treatment of protein solution enhanced their encapsulation and retention. [ABSTRACT FROM AUTHOR]

The aim of the present study was to fabricate catechin-egg white protein (CT-EWP) conjugates as novel food-grade antioxidant emulsifiers designed to improve the physicochemical stability of β-carotene (BC) emulsions. CT-EWP conjugates were synthesized using free radical grafting, and the formation of conjugates was confirmed by electrophoresis and liquid chromatography-mass spectrometry. The physicochemical stability of BC emulsions was characterized by measuring alterations in particle size, ζ-potential and BC retention. The particle size and ζ-potential changed more rapidly at 37 °C than at 4 or 25 °C, however no creaming or oiling-off were observed at any of the storage temperatures, suggesting all emulsions were physically stable throughout the 30-day storage period. Compared to emulsions stabilized by EWP or CT + EWP physical mixtures (no conjugation), CT-EWP conjugate-stabilized emulsions had better resistance to environmental stresses, such as thermal processing and high ionic strengths, which was attributed to a stronger steric repulsion between the oil droplets. CT-EWP conjugates also significantly reduced the degradation rate of BC in emulsions during storage ( p < 0.05), which was attributed to their strong antioxidant and interfacial activities. These results indicate that CT-EWP conjugates can be utilized to develop food-grade delivery systems to protect chemically labile lipophilic bioactive compounds. [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]

Previously, it was shown that activated carbon can remove phenylalanine from egg white hydrolysates to produce a low phenylalanine peptide ingredient that can be used by individuals suffering from phenylketonuria. However, the factors impacting the selective adsorption of phenylalanine and peptides to activated carbon is not fully understood, which is holding back the optimization of this process. In this research, two activated carbons with different morphologies and electrical characteristics were used to adsorb egg white hydrolysates with different degrees of hydrolysis. The selective adsorption behavior of the different constituents within the hydrolysates was studied to identify the nature of the adsorption mechanisms involved. The results showed that aromatic amino acids and components with higher molecular weight were preferentially adsorbed. Moreover, the main driving force for adsorption was hydrophobic attraction, followed by hydrogen bonding and electrostatic interactions. These results could facilitate the preparation of medical foods for patients with phenylketonuria. [ABSTRACT FROM AUTHOR]

The application of industrial egg white powder (EWP) was limited by the relatively poor foaming properties. Microwave treatment was proposed to be a creative and efficient technology to improve the functionality of EWP. This study focused on the physicochemical properties and baking performance of EWP undergoing microwave treatment at the presence of maltodextrin (MD). The solubility, fluorescent properties, molecular weight and secondary structure of protein were investigated to verify the glycation and structure transformation. The baking performance of the modified EWP was thoroughly investigated by foaming properties, specific volume, water content, microstructure, and sensory analysis. The microwave treated EWP at presence of MD showed smaller particle size and higher surface hydrophobicity than untreated EWP. The result of molecular weight distribution and FTIR spectrum verified the covalent binding of –OH abundant MD on the EWP molecule. The foaming ability of EWP after microwave treatment was increased from 4.84 mL/g to 6.18 mL/g at the presence of MD. The enhanced hydrophobic interaction and hydrogen bonding between protein molecules were the main beneficial factors affecting foaming properties and baking performance of EWP. This study was meaningful for promoting the application of microwave-assisted glycosylation reaction in the functional modification of proteins. [Display omitted] • Microwave assisted Maillard reaction between of egg white protein (EWP) and Maltodextrin (MD). • Glycated EWP was characterized by structural expansion and hydroxyl enrichment. • Foaming ability of EWP was greatly improved after glycation related to the water holding ability. • Glycated EWP showed excellent baking performance. [ABSTRACT FROM AUTHOR]

Epigallocatechin-3-gallate (EGCG) is a kind of polyphenol with various biological activities but poor stability and bioavailability. The encapsulation of EGCG in a nano-delivery system effectively improves its shortcomings. In this research, co-assembled nanoparticles of egg white protein, phosphatidylcholine (PC), and EGCG (EW/PE 1:5 NPs) were prepared by antisolvent precipitation to improve their bioavailability. The constructed EW/PE 1:5 NPs had an average particle size of 172 nm, a ζ-potential of −26.1 mV, and a polymerization dispersion index (PDI) of 0.33. The encapsulation efficiency (EE) of EGCG was 88.09% and the loading capacity (LC) was 20.10%. UV spectra, FTIR, XRD and intermolecular force results indicated that hydrophobic, electrostatic and hydrogen bonding interactions contributed to the formation of EW/PE 1:5 NPs. EW/PE 1:5 NPs exhibited Fick diffusion and sustained release characteristics in simulated gastrointestinal digestion. In addition, the transcellular permeability of EW/PE 1:5 NPs was significantly increased compared with free EGCG. At the same time, EW/PE 1:5 NPs increased EGCG absorption transport and inhibited MRP2 and P-gp-mediated efflux transport. These results suggest that EW/PE 1:5 NPs play a key role in improving the bioavailability of EGCG. Therefore, EW/PE 1:5 NPs are expected to provide a theoretical basis for the design and development of functional foods or dietary supplements that synergistically enhance the bioavailability of EW, PC and other flavonoids. [Display omitted] • EW/PE 1:5 NPs exhibit Fick diffusion and sustained release in in-vitro digestion. • EW/PE 1:5 NPs improve absorptive transport and transcellular permeability of EGCG. • EW/PE 1:5 NPs demonstrate inhibition of MRP2 and P-gp mediated efflux transport. • EW/PE 1:5 NPs are uptaken by clathrin-dependent endocytosis, macropinocytosis, and caveolin-mediated endocytosis. • EW/PE 1:5 NPs significantly improve the bioavailability of EGCG. [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]

Summary: Overconsumption of fat‐rich foods has led to a significant increase in the incidence of chronic diseases in humans. With the increased pursuit of a healthy lifestyle, low‐fat products are gradually developing. In this study, egg white protein microparticle (EWPM) was used as a fat mimetic in low‐fat mayonnaise, as well as xanthan gum (XG) and gum arabic (GA) were used as texture and rheology modifiers. The results showed that XG and GA had a synergistic effect on modifying viscosity and recovery of EWPM‐structured low‐fat mayonnaise. The addition of XG could effectively increase the viscosity of low‐fat system, due to the electrostatic binding with EWPM and the intermolecular entanglement. The incorporation of XG with GA could effectively intervene intermolecular interactions to improve recovery, verified by the decreased particle size and weakened electrostatic binding. The results would provide practical guidance for the development of high‐protein and low‐fat nutritious mayonnaise. [ABSTRACT FROM AUTHOR]

BACKGROUND: Isolation of lysozyme from egg white (EW) using ion exchange resin adsorption method generates large quantities of lysozyme‐free egg white (LFEW) with poor gelling property. To maximize the applications of LFEW, the effect of Lactiplantibacillus plantarum fermentation on the gel properties of LFEW was investigated in this study. RESULTS: The fermentation efficiency of LFEW with lysozyme removed was significantly improved, and the sugar removal rate (2 g kg−1Lactiplantibacillus plantarum, 37 °C, 7 h) was more than 90%. Removal of lysozyme resulted in increased stability and surface hydrophobicity of EW. After Lactiplantibacillus plantarum fermentation, the stability of EW decreased, and the average particle size and surface hydrophobicity increased. In addition, by comparing the gel properties of EW and LFEW before and after fermentation at different pH, it was found that the hardness, elasticity, and water holding capacity (WHC) of EW gel increased significantly. The removal of lysozyme effectively improved the WHC and springiness of the EW gel and promoted the formation of a denser network structure with smaller pores. After Lactiplantibacillus plantarum fermentation treatment, LFEW gel hardness decreased, with loose and porous network structure, no browning occurred after autoclaving. CONCLUSION: This study provided the direction and theoretical basis for producing a fermented LFEW gel with pleasing texture and appearance. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Summary: Desugaring is a necessary step to prevent undesirable attributes of the egg white (EW) products. In this study, the effects of yeast fermentation and glucose oxidase (GOD) method on the functionalities of EW were compared. Yeast fermentation treatment led to the formation of poor EW gel with low hardness due to the porous structure brought by increased foam capacity (FC). In contrast, GOD treatment increased the hardness of EW gel by increasing the surface hydrophobicity (H0) and ordered secondary structure and decreased the foaming capacity and stability of EW by decreasing absolute potential. In addition, the foam structure became more compact after yeast fermentation compared to GOD treatment. However, the water holding capacity (WHC) of both EW gels with desugaring treatments decreased due to the porosity of the internal gel network confirmed by scanning electron microscopy. These results provide a guide for the selection of sugar‐free EW liquid in the subsequent application. [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]

This study investigated the interaction between egg white protein particles (EWPP) and rhamnolipid (Rha) as co-emulsifiers in high internal phase emulsions (HIPEs). To reveal the effect between EWPP and Rha on the properties of HIPEs, the physicochemical properties (particle size, zeta-potential and microstructure) and emulsifying capacity were investigated. The results showed that, with the increase in Rha content, the EWPP-Rha complex could be divided into three regions according to the emulsifying capacity. The emulsion properties at different regions were analyzed by microstructure, rheology and nuclear magnetic resonance etc. The addition of Rha may compete interface with EWPP, adjusting the properties of constructed HIPEs. Generally, the replacement of EWPP by Rha from interface decreased emulsion droplets and disrupted the inter-droplet network, resulting to the formation of soft and flexible emulsions. The incorporation with Rha was beneficial for improving the emulsifying capacity of EWPP. In Rha sufficient system, more EWPP distributed in the aqueous phase of constructed HIPEs and functioned as a stabilizer to increase coalescence stability. The study was meaningful for revealing the complicated relation between protein particle and surfactant, and improving properties of high internal phase emulsions combining the advantages of each emulsifier. [Display omitted] • The combination of EWPP and Rha improved the emulsifying capacity immensely. • The addition of Rha was helpful for decreasing the droplet size of HIPEs. • EWPP was beneficial for improving coalescence and thermal stability of the HIPEs. [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]

Dry heat treatment is normally used to improve foaming properties of egg white powder (EWP), which actually needs long production cycle with low efficiency. In this study, microwave technology was adopted to improve the foaming properties of EWP and the relationship between structure and foaming properties of EWP was investigated. The results showed that appropriate intensity of microwave treatment could induce the transition from β-sheet structures to α-helix and random coil structures. And the secondary structure of EWP after microwave treatment at 440 W for 6 min was 32.6% α-helix, 14.1% β-sheet, 17.5% β-turn and 35.8% random coil, which was similar to the structure of natural protein in egg liquid (unspray-dried). Meanwhile, the viscosity and flexibility of egg white protein were improved, which were beneficial to the protein adsorption at interface and enhancement of foam ability. Furthermore, the higher solubility and lower surface tension could be related to the fragmentation of microwave-treated egg white powder, which were helpful to the quick diffusion and adsorbance of egg white protein at interface. Therefore, the foam ability of EWP was raised to 4.84 mL/g after microwave treatment at 440 W for 6 min, having 15.3% higher than conventional dry-heat treated EWP. Image 104918 • Solubility of egg white protein treated by microwave increased significantly. • Microwave treatment promoted the transition of β-sheet to α-helix. • Secondary structure of egg white protein treated by microwave was similar to egg liquid (unspray-dried). • Foam ability of egg white protein was remarkably improved by microwave treatments. [ABSTRACT FROM AUTHOR]

Spray-dried egg white powder (EWP) is limited to be used as the raw material in beverage industry due to its poor dispersibility. In this work, a new method that combined heating and enzymatic hydrolysis was proposed to resolve this problem. Appropriate heating treatment could obviously increase the dispersibility of EWP by increasing its particle size, whereas enzymatic hydrolysis could degrade the thermolabile proteins and release the highly negative polypeptides, thus increasing the stability of EWP in water. The highest coefficient of stability (COS) was achieved when the amount of enzyme addition was 0.03% with 75 °C heat treatment (75 + 0.03). Also in this condition, many concave holes on the surface of EWP (75 + 0.03) can be observed, which was beneficial to the wettability. These results indicate that the heat and enzymatic treatment have a synergistic effect in improving the dispersibility and thermostability of EWP. • Heat and protease together improved the dispersibility of egg white powder (EWP). • The dispersion rate of EWP was enhanced by heat-induced aggregation of proteins. • The dispersion stability of EWP positively correlated with net charge. [ABSTRACT FROM AUTHOR]

Due to the poor thermal stability of egg white protein (EWP), important challenges remain regarding preparation of nanoparticles for EWP above the denaturation temperature at neutral conditions. In this study, nanoparticles were fabricated from conjugates of EWP and isomalto-oligosaccharide (IMO) after heating at 90 °C for 30 min. Meanwhile, the effects of protein concentration, temperature, pH, ionic strength and degree of glycation (DG) on the formation of nanoparticles from IMO-EWP were investigated. To further reveal the formation mechanism of the nanoparticles, structures, thermal denaturation properties and surface properties were compared between EWP and IMO-EWP conjugates. Furthermore, the emulsifying activity index (EAI) and the emulsifying stability index (ESI) of nanoparticles were determined. The results indicated that glycation enhanced thermal stability and net surface charge of EWP due to changes in the EWP structure. The thermal aggregation of EWP was inhibited significantly by glycation, and enhanced with a higher degree of glycation. Meanwhile, the nanoparticles (<200 nm in size) were obtained at pH 3.0, 7.0 and 9.0 in the presence of NaCl. The increased thermal stability and surface net negative charge after glycation contributed to the inhibition. The EAI and ESI of nanoparticles were increased nearly 3-fold and 2-fold respectively, as compared to unheated EWP. [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 To investigate the potential of glycation and/or heat modified egg white protein (EWP) as stabilizer for oil-in-water emulsions, glycated EWP (GEWP) was prepared by a dry-heated Maillard reaction using EWP and isomalto-oligosaccharide. Heat-induced GEWP nanoparticles (HGN) were then fabricated by heating GEWP at 90 °C for 30 min at pH 6.0–9.0. The physicochemical characteristics (particle diameter, ζ-potential and surface hydrophobicity) and emulsifying capacity of GEWP and HGN were investigated. In addition, the storage, oxidation, thermal treatment and salt stabilities of emulsions prepared with GEWP and HGN were evaluated. The results indicated that the emulsions prepared with modified EWPs exhibited higher protein adsorption on the oil-water interface and smaller particle size. The GEWP- and HGN-stabilized emulsions were stable against droplet aggregation during storage and exhibited better oxidation stability, which may be related to the enhanced antioxidant activity and absorption ability of the modified EWPs. Additionally, the emulsions prepared with GEWP and HGN exhibited higher heat and salt stabilities due to the increase in surface hydrophobicity and net charge. The thermostable structure of the proteins induced by glycation and heat treatment also contributed to the improvement in heat stability. Overall, the HGN-stabilized emulsions exhibited the best physicochemical stability among the modified EWPs. Graphical abstract Unlabelled Image Highlights • Emulsions of glycation/heat modified egg white proteins had smaller particle size. • The modified egg white proteins possessed the higher adsorption at oil-water interface. • The modified egg white proteins exhibited better emulsion stability. • Higher surface hydrophobicity and smaller size contributed to the emulsion stabilization. [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]

• Alkaline salts promote the formation of elastic egg white gel with low lightness. • Ionic strength and pH act differently in modulating the protein aggregation state. • The extent of protein aggregates cross-linking affected digestibility of the gel. In this study, the thermal gelation and digestion properties of hen egg white (hen EW) proteins with different salts were investigated. Results show that the addition of neutral salt - sodium chloride (NaCl) decreased the gel hardness/resilience, increased gel lightness, aggregated particle size and digestibility of hen EW proteins significantly. In contrast, alkaline salts – phosphate and carbonate addition increased the gel resilience and strain tolerance as well as reduced the aggregated particle size and gel lightness of hen EW proteins due to the increase of solution pH and negative charge. Correlation analysis shows that the digestibility of hen EW gels was affected by gel viscoelasticity, molecule forces and texture. In conclusion, thermal gelation properties of hen EW proteins could be modulated by salts with different pH/ionic strength, and thus affected the protein digestion and peptide released. [ABSTRACT FROM AUTHOR]

In this study, the influence of three selected gums including neutral locust bean gum (LBG), guar gum (GG), and anionic xanthan gum (XG) on the foaming and baking properties of egg white (EW) powders were investigated. Results showed that the surface tension, particle size, viscosity and interfacial adsorption modulus of reconstituted EW solutions prepared by EW powders increased with the addition of gums, along with the decrease of surface hydrophobicity, especially in the presence of the anionic XG. The kinetic analysis of foam formation showed that the addition of gums, especially for LBG and GG, were beneficial to the rapid infiltration of air in foam, thus dramatically reducing the whipping time in the preparation of cake batter. Furthermore, the angel cakes prepared by reconstituted EW solutions containing LBG or GG had higher specific volume than fresh EW. These results showed that the addition of neutral gums can improve the baking performance of EW powders by increasing the foaming rate and capacity. This study provided an insight on improving the foaming performance of EW powders by incorporating gums. [Display omitted] • Selected gums enhanced the air/water interface adsorption of egg white (EW) proteins. • The foaming capacity of reconstituted egg white solutions with gums was improved. • Viscosity was closely related to the foaming rate of the reconstituted EW solutions. • Locust bean gum/guar gum improved the baking performance of EW powder. [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]

Transglutaminase (TGase) and succinylation could modify the physicochemical characteristics and the functional properties of proteins. The aim of this work was to cross-link egg white protein (EWP) and succinylated casein with TGase and to assess the feasibility of making a novel composite protein film. The effects of succinylated casein content, reaction time, and TGase concentration on the mechanical properties, physical characteristics (thermal property and degree of crystallinity), and structure properties (secondary structure and surface micrograph structure) of the film were investigated in this study. The results revealed that the susceptibility of EWP to TGase-mediated cross-linking modification was enhanced by succinylated casein. Meanwhile, the films with TGase were more homogeneous and smoother and possessed better water resistance and thermal stability. The content of α-helix, β-turn structures were increased whereas β-sheet structure was decreased. The spatial conformation and degree of crystallinity of composite protein film were also affected by TGase. The increase of the degree of crystallinity of the composite film further proved the improvement of film mechanical properties induced by TGase and succinylated casein. Based on the above results, this study provides relevant data and insights for the TGase/chemical modification of protein-based edible films. [ABSTRACT FROM AUTHOR]

The deterioration of foaming performance of spray-dried egg white powder (EWP) dramatically affects its application in aerated foods. This study compared the effects of spray drying at different outlet temperatures (70, 80 and 90 °C) and freeze drying on the foaming properties of EWP. The results showed that the foaming capacity/foam stability of reconstituted EW solutions prepared by spray-dried EWP significantly decreased with the increase of outlet temperatures and was far smaller than freeze-dried ones. Correlation analysis results showed that the foaming performance of spray-dried EWP was highly correlated with the particle size, surface tension and interface adsorption behavior. The understanding of drying effect on their foam properties could assist in selecting the appropriate drying methods and measures to optimize the utilization of EWP in the food industry. • The foaming performance of egg white powder decreased at high drying temperature. • Drying induced protein aggregation slowed down its interfacial adsorption capacity. • The surface tension and viscosity of egg white dominate its foaming performance. [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]

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 explored the construction of egg white protein particles (EWPP) and/or rhamnolipid (Rha) based emulsion gels with β-sitosterol (Sit) as gelation factor. The properties of the emulsion gels and the application in cookies were investigated to further reveal the functional mechanism of each component. The rheological and microstructure results of the emulsions showed that emulsion gels had suitable plastic texture with lower melting rate and faster cooling rate compared with butter. EWPP stabilized the droplet while Rha reduced the droplet size and enhanced the fluidity of the emulsion gels. In cookie system, Sit in the emulsion gels provided the appropriate hardness and uniform matrix with emulsifiers. EWPP and Rha effectively improved the appearance, texture and mouthfeel of cookies and extended cookies' frangibility during storage. The constructed composite emulsion gels showed promising potential as plastic fat substitutes, to be used in healthy bakery systems to decrease saturated fatty acids. [Display omitted] • In corporation with Sit as gelation factor could improve the hardness of EWPP and/or Rha based emulsion gels. • In composite emulsion gels, EWPP was helpful for stabilizing the droplets, and Rha could greatly reduce the droplet size. • Sit addition avoided backlog of starch granules and promoted the formation of uniform cookie matrix with emulsifiers. • EWPP, Rha and Sit composite emulsion gel prepared cookie had similar sensory properties as butter prepared cookie. [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]

Abstract: Lysozyme from hen egg white is a well-known antimicrobial protein with high ratio of hydrophobic and positively charged amino acid residues. In order to explore functional bioactivities of enzymatic hydrolysates of lysozyme, the protein was subjected to a simulated gastrointestinal digestion and the resulting hydrolysate (LPH2) showed a strong competitive angiotensin I-converting enzyme (ACE) inhibitory activity (IC50 =12.6μg/ml) and a remarkable antioxidant activity. The LPH2 was fractionated using a 3kDa cut-off membrane and the obtained permeate LPH2–3kDa was analysed by MALDI-TOF-TOF MS. Using this technology, 38 different peptides were identified and some of these peptides were well fit with structure requirements of ACE inhibitory peptides and/or antioxidant peptides. The findings from this study suggest that the protein containing high proportion of hydrophobic and positively charged residues have the potential to generate multifunctional peptides, and these peptides would be beneficial ingredient to be used in functional foods. [Copyright &y& Elsevier]

The effects of dry-heat treatment (75 °C, 0–20 d) and guar gum (GG) composition on foaming properties and baking performance of egg white powder (EWP) were investigated. Rheological measurement showed that both dry-heat treatment and GG addition can improve the viscosity of EWP dispersion. The particle diameter of EWP dispersion decreased after dry-heat treatment, while hydrophobicity increased, indicating that the increased viscosity was caused by the enhanced hydrophobic interaction rather than particle induced steric hindrance. The sample undergoing 10 days of dry heating with GG addition performed the best foaming properties (foaming capacity 9.37 ± 0.26 mL/g and foaming stability 96 ± 1.56%). However, without GG addition, 10 days of dry heating just induced the foaming capacity and stability increasing from 5.17 ± 0.65 mL/g and 42.85 ± 2.90% to 6.96 ± 0.09 mL/g and 64.95 ± 3.04%, respectively. The sample EWP 10 + GG also exhibited the largest cake specific volume and uniform distribution of foams in cross section, which was observed in all three baking systems (low, middle and high sugar). In low sugar system, GG addition induced an increase in cake specific volume from 3.72 ± 0.02 mL/g to 4.55 ± 0.16 mL/g. The results revealed that combining dry-heat and GG addition can more effectively enhance foaming capacity and baking performance of EWP powder, providing guidance for its efficient application in baking industry. Image 1 • Dry-heat treatment can decrease particle size of egg white powder (EWP) aggregates. • Guar gum (GG) addition increases surface hydrophobicity and viscosity of EWP. • Addition of GG to dry heated EWP improved foaming properties significantly. • EWP with 10 days' dry-heat and GG addition displays the best baking performance. [ABSTRACT FROM AUTHOR]

Glycation with fructo-oligosaccharide (FO) and isomalto-oligosaccharide (IMO) was employed to improve the heat-induced egg white protein (EWP) gels. Results showed that EWP glycated with IMO exhibited a greater degree of glycation (DG) and better gelling properties than those of FO-EWP conjugates. The electrophoresis and liquid chromatography mass spectrometry (LC-MS) indicated that IMO was successfully covalently cross-linked with EWP. Fourier transform infrared spectroscopy (FTIR) showed that the glycation increased the percentages of intramolecular and intermolecular β-sheets of EWP and lowered the contents of 3 10 -helical structure. The rheological test indicated that the gel-forming temperature of EWP was brought forward with the increase of glycation time. Furthermore, the glycation could induce the formation of EWP gel characterized by the higher strength of hydrogen bonds and hydrophobic interactions and lower strength of disulfide bonds. The changes of intermolecular forces resulted in a fine network structure of EWP gel, which significantly enhanced the fracture strength, bound water relaxation proportion and water-holding capacity (WHC) of the gel. A positive correlation existed in the WHC and gel fracture strength. This study proved that glycation with IMO efficiently improved the gelling properties of EWP. Image 1 • Isomalto-oligosaccharide had better glycation effect than fructo-oligosaccharide. • Gel fracture strength of egg white protein (EWP) was increased after glycation. • Glycation increased the hydrogen bond and hydrophobic interaction of EWP gel. • Gel T2 relaxation proportion and water-holding capacity increased after glycation. [ABSTRACT FROM AUTHOR]

• Heavy-metal-free pidan-like products were obtained by combining pickling with heat treatment. • NaOH in the brine solution could promote the salt penetration into egg whites. • The degradation of protein would affect the gel intermolecular forces. • Gel springiness recorded a significantly positive correlation with hydrogen bonds. Effects of the brine solution with different NaOH concentrations on the physicochemical properties, intermolecular forces, and gel properties of duck egg whites were studied. The free alkalinity, salt content and surface hydrophobicity of egg whites increased as the pickling time and NaOH concentration increased. The primary intermolecular forces (disulfide bonds and hydrophobic interactions) in the alkali egg white gels were increased firstly and then decreased, resulting from the fact that the proteins were degraded under strong alkali conditions during the late stage of the pickling process. Changes of hardness and springiness of egg white gels were closely related with the interactions of the protein molecules. Thereinto, the change tendency of springiness was in accordance with the changes of hydrogen bond of egg white gels. The colour of the egg white gels obtained from alkali treatment changed from white to amber during pickling. [ABSTRACT FROM AUTHOR]