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Steamed bread has long been an important part of Chinese cuisine. This study investigated the effects of salted egg white (SEW) (5, 10, 15, and 20% w/w) on the quality of steamed breads. Findings revealed that SEW notably enhanced the bread's volume and texture, with a 20% inclusion significantly boosting water retention and rheological properties, albeit reducing bread's lightness. In addition, the H-bond absorption band intensity in the Fourier transform infrared spectroscopy (FTIR) analysis showed increased peak intensities with higher SEW levels, indicative of protein structure alterations. X-ray diffraction confirmed the presence of an amylose-lipid complex. Scanning electron microscope (SEM) and Confocal laser scanning microscope (CLSM) imaging depicted a smooth, consistent protein network with SEW addition. Consumer sensory evaluation responded favourably to the SEW15 steamed bread, suggesting its potential for food industry application. Overall, the study considers SEW an effective ingredient for improving steamed bread quality., 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.)

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.)

In addition to small amounts of minerals and carbohydrates, most of the dry matter of chicken egg white is protein, making egg white an ideal resource for obtaining food proteins. Ovalbumin (OVA), which accounts for more than 50% of the total egg white protein, is one of the most widely studied food proteins due to its multiple functional properties, and it has also been used as a model protein molecule in many research fields. The objective of this study was to develop a simple and rapid method for the purification of OVA from egg whites on large scale. First, OVA was separated from ovomucin, ovotransferrin, and ovomucoid by polyethylene glycol (PEG) concentration, using the following optimal parameters: the PEG concentration was 15%, the pH was 6.5, the salt concentration was 100 mmol/L, and the operating temperature was 10°C. The OVA-rich supernatant obtained from PEG precipitation was further purified by isoelectric precipitation at a pI of 4.5 and a temperature of 4°C, and the purified OVA was obtained with at a purity of 95.1% by HPLC, with a yield of 46.4%. After the extraction of OVA, the PEG solution was vacuum dried and then utilized cyclically in the PEG precipitation steps. The whole purification process could be finished within 2 to 3 h at a scale of several kilograms of egg white. This method has the advantages of rapidity, simplicity, low cost, and ease of scalability., (© 2018 Poultry Science Association Inc.)

As the most abundant protein in chicken eggs, ovalbumin plays an important role in the processing of high value-added poultry products. The present study investigated the effects of hydroxyl radical-induced early stage oxidation on the physicochemical and interfacial properties of chicken egg white ovalbumin. Protein carbonyl content of ovalbumin increased (from 0.78 to 1.13 nmol/mg) with the oxidation time (0-5 h), while free sulfhydryl content (from 0.43 to 0.09 nmol/mg) and free amino group content (from 0.49 to 0.43 nmol/mg) decreased. Sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis showed that the exposure of ovalbumin to hydroxyl radicals caused self-cross-linking and resulted in the formation of dimers and trimers. Accompanied by these changes, the surface hydrophobicity of ovalbumin was enhanced about 1.5-fold with the deepening of oxidation, and the value of zeta potential became more negative (from -7.15 to -20.51 mv). About 2 h of moderate oxidation improved the foaming and emulsifying properties of ovalbumin (1.2-fold to 1.8-fold), while excessive oxidation (3 h) decreased these interface properties. Hydroxyl radical-induced oxidation changed the surface chemical groups and structures of ovalbumin, thereby affecting the surface properties. The foaming and emulsifying properties of ovalbumin could be improved by oxidation, increasing the application possibilities of ovalbumin in the food interface system., (© 2018 Poultry Science Association Inc.)

Glycosylation of proteins plays an important role in their biological functions, such as allergenicity. Ovomacroglobulin (OVMG) is a glycoprotein from hen egg white, but few studies have been done so far to delineate the glycosylated sites of OVMG. The present study characterized the glycosylation of OVMG using mass spectrometry and two-dimensional electrophoresis. MALDI-TOF-MS showed that the OVMG subunit [M + H](+) ion has a peak at m/z 183297; therefore, the carbohydrate moiety is calculated as 11.5% of the whole OVMG molecule. HPLC-ESI-MS/MS confirmed that of 13 potential N-glycosylation sites of OVMG, 11 sites were glycosylated; 1 site (N(1221)) was found in both glycosylated and nonglycosylated forms. On the two-dimensional electrophoresis gel, a series of OVMG spots horizontally distributed at 170 kDa, with an isoelectric point range of 5.03-6.03, indicating the heterogeneity of glycosylation of OVMG. These results provided important information for understanding of structure, function, and potential allergenic sites of OVMG.

Hen egg white (EW) are one of the most ideal sources of active proteins, and ovomacroglobulin, as a protease inhibitor, has been demonstrated to possess numerous biological properties including antibacterial and anti-inflammatory properties as well as activity for the treatment of keratitis. The objective of this study was to develop a simple and rapid method for the purification of ovomacroglobulin from hen EW on a laboratory scale. Hen EW was diluted with an equal volume of distilled water followed by a two-step PEG precipitation to remove ovomucin and to obtain ovomacroglobulin-rich precipitate. The precipitate was dissolved and further purified by gel filtration chromatography. Ovomacroglobulin was collected with a purity of 97.0 ± 0.3% by HPLC and a yield of 62.5%. The atomic force microscopy images showed that ovomacroglobulin molecules on a mica surface emerged as an "oval-shaped plate" with a molecular volume of 1536.9 ± 330.0 nm(3) , indicating that purified ovomacroglobulin has an integrated molecular structure. With the improvement of PEG precipitation and the simplification of the chromatography, the whole purification process could be finished well within one working day. This protocol has an advantage of rapidity, and would facilitate studies of ovomacroglobulin., (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Although the effect of storage temperature was suggested to be a more important factor than that of storage time on changes in unfertilized egg white proteins, no comprehensive analysis of the thermally induced egg white protein changes was carried out. This study presents a proteomic analysis of the changes in unfertilized egg white proteins after 15 days of storage at 4, 20, and 37 °C. Using two-dimensional electrophoresis followed by MALDI-TOF MS/MS, 32 protein spots representing 8 proteins were identified with significant differences in abundance when stored at different temperatures. An accelerated degradation of ovalbumin, possibly resulting from the reduction of antiprotease, was observed after the storage at higher temperature. In addition, an increase in the formation of ovalbumin complexes and a decrease in lipocalin family proteins were detected with increasing storage temperature, which may indicate a thermally promoted change in chicken eggs. The decrease of clusterin during the high-temperature storage was suggested to be an effective biomarker for egg quality evaluation. These findings will give insight into the effects of storage temperature on changes in unfertilized egg white proteins during storage and provide a better understanding of the thermally induced biochemical changes that may affect the egg deteriorative process.

Avian egg albumen participates in embryonic development by providing essential nutrients as well as antimicrobial protection. Although various biological functions of egg white proteins were suggested during embryogenesis, global changes of these proteins under incubation conditions remained uninvestigated. This study presents a proteomic analysis on the change of egg white proteins during the first week of embryonic development. By using 2-DE, together with MALDI-TOF MS/MS, thirty protein spots representing eight proteins were identified showing significant changes in abundance during incubation. An accelerating degradation of ovalbumin was observed in a wide range of molecular weight. In addition, four protein complexes were predicted according to the detected molecular weight increase. Among these speculated protein complexes, an ovalbumin spot coupled with RNA-binding protein was detected. The absence of these protein complexes before incubation, followed by the constant increase in abundance during incubation indicates conceivable pivotal roles in embryonic development. To better understand the function of the proteins identified in this study, discrepancies of egg white protein changes between fertilized and unfertilized chicken eggs were additionally demonstrated. These findings will provide insight into the embryogenesis process to improve our knowledge of egg white proteins in regulating and supporting early embryonic development., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Ovomucin has been considered to contribute a lot to the excellent functional properties of egg white. This work focused on investigating the effects of pH and protein concentration on foaming and emulsifying properties of ovomucin to evaluate the proper use of this egg protein as a functional food ingredient, and to clarify its contribution to the functional properties of egg white under different pH conditions. Protein solubility and surface hydrophobicity were measured through the pH ranged from 2.3 to 11.0. Alkali treatment gave ovomucin improved emulsification properties, which were correlated well with the surface hydrophobicity ( r≥ 0.89, P < 0.01). Although ovomucin showed lower foaming capacity in acid and neutral solution, enhanced foaming stability was observed with weak acid-treated ovomucin (pH 5 to 6) compared to native ovomucin. These results demonstrated that acid and alkali treatment, which leads to partial unfolding of ovomucin can improve functional properties of ovomucin, with the greatest improvement for emulsification properties being from the alkali treatment and for foaming stability being from weak acid treatment. These results are helpful to produce unfolding ovomucin suitable for wide range of applications in food industry, and to provide useful information on the proper use of egg white in different food systems. Practical Application: Ovomucin plays a critical functional role in egg white products. However, it is typically insoluble in distilled water or common salt solutions, which has thus limited its commercial applications. Alkaline treatment resulted in gradual increase in solubility, which markedly enhanced the emulsifying properties, on the other hand foaming stability of ovomucin can be promoted by weak acid treatment. The results of this work help to produce unfolding ovomucin suitable for wide range of applications in food industry, and to provide useful information on the proper use of egg white in different food systems. [ABSTRACT FROM AUTHOR]

This study investigated the impact of ultrasound pretreatment and phenolic binding on the structure characteristic and foaming properties of egg white (EW). EW treated without ultrasound (NEW) and with ultrasound (UEW) (power for 28% and time for 25 min: on-time 3 s and off-time 2 s) were incubated separately at 25 °C for 2 h with gallic acid (GA) and epigallocatechin gallate (EGCG) at pH 7.0. Phenolic treatment caused a significant loss of sulfhydryl content, with a more remarkable effect observed in UEW, especially at 120 μmol/g concentration. Both phenolics significantly decreased the surface hydrophobicity and slightly increased the disordered secondary structure of protein. Additionally, the microenvironment polarity of protein molecules was increased by phenolic treatment corroborated by UV absorption blue shift, especially for 240 μmol/g GA-UEW. After ultrasound pretreatment, low EGCG concentration (20 μmol/g) significantly increased the foaming ability. The 240 μmol/g EGCG treatment notably increased the reduced foaming stability by ultrasound from 81.00 to 95.10% (p < 0.05), which was due to high absolute ξ-potential value. This study has shed light on the mechanisms underlying the influence of unfolding structure by ultrasound treatment on phenolic binding. Image 1 • Phenolic treatment especially EGCG significantly decreased sulfhydryl content. • Protein surface hydrophobicity was obviously decreased by phenolic treatment. • EGCG treatment increased the foaming stability of egg white. • EGCG was stronger than GA in binding affinity with egg white. • Ultrasound pretreatment contributed to the binding of phenolic to protein. [ABSTRACT FROM AUTHOR]

The foaming property of egg white (EW) is essential in food processing. In this study, we investigated the effect of ultrasound combined with adding different concentrations (0, 0.4, 0.5, 0.6, 0.7, and 0.8 %, m/v) of flaxseed gum (FG) on EW foaming. The results showed that the cooperation of ultrasound treatment and FG significantly improved the foaming stability. Regarding details, FG reduced the sulfhydryl content and surface hydrophobicity of EW proteins while increasing the average particle size and PDI value. Despite the ultrasound treatment, FG significantly improved the foaming stability from 62.83% to 99.82% (p < 0.05). Based on the analysis of ξ-potential, surface tension, rheology, etc., FG improved the EW microenvironment, which is conducive to foaming stability. As a new type of polysaccharide, FG combined with ultrasound can significantly improve the foaming properties. This research could solve the problem of reduced foaming stability of EW treated by ultrasound alone, making promising applications in the food industry. [Display omitted] • Ultrasound combined with flaxseed gum improved the foaming of egg white. • Flaxseed gum overcame the problem that ultrasound reducing the foaming stability. • Flaxseed gum formed a viscoelastic interfacial film to increase surface tension. • Egg white protein's structure was more compact and increased foaming stability. [ABSTRACT FROM AUTHOR]

Herein, we proposed an interconnected-porous chitosan macroparticles (IPCMs) immobilized papain to exactly control the enzymatic hydrolysis degree of egg white (EW) via a non-heating technology in order to improve its foamability. The SEM images showed that the sodium carbonate (Na 2 CO 3) as gas porogen with varying concentration was able to improve the porosity structure of surface layer of interconnected-porous chitosan macroparticles (IPCMs). The activity determination results indicated that the IPCMs prepared with 0.4 M Na 2 CO 3 hold the highest activity immobilized of papain. In comparison with free enzyme, immobilized papain had a higher range of pH and temperature adaptability, as well as the thermal stability. With a limited hydrolysis, the immobilized papain obtained through condition optimization could enhance the foaming capability (FC) and foaming stability (FS) of EW to 646.67% and 71.62%, respectively. The Fourier transform infrared spectroscopy (FTIR), particle size, zeta potential and surface hydrophobicity were used to analyze the molecular structure change of EW after hydrolysis. Importantly, the immobilized papain could control the enzymatic reaction processing via simple separation, ensuring the optimal hydrolysis degree of EW for foamability enhancement, it also prevented the decrease in foamability during storage due to continuous enzymatic hydrolysis. [Display omitted] • Na 2 CO 3 can improve the porosity structure of the surface layer of IPCMs. • The IPCM-immobilized papain possesses a great stability to environment. • The IPCM-immobilized papain can achieve the controllable hydrolysis of egg white. • Foamability of egg white is improved about 2 folds by controlled hydrolysis. • Improved foamability via IPCM-immobilized papain will not decrease during storage. [ABSTRACT FROM AUTHOR]

The effects of shell egg cold storage (4 °C) on the foaming properties of its egg white were investigated by evaluating its physicochemical changes. The foaming ability decreased significantly (p < 0.05) while the foaming stability decreased slightly during cold storage. Specifically, the foam ability reached the minimum (25.17%) at 40 d of storage, which was decreased by 44.49% versus that at 0 d (45.33%). In the first 40 d, the decrease in foaming ability was mainly ascribed to the decreased surface hydrophobicity and the increased surface tension. Moreover, the exposed sulfhydryl groups tended to cause protein cross-linking probably by sulfhydryl-disulfide exchange reaction, leading to an increase of particle size and viscosity. However, during the 60–80 d storage, the decrease of sulfhydryl content and viscosity tended to inhibit foam formation. Additionally, more larger protein aggregates were observed with prolonging of storage period under a scanning electron microscope. This investigation reveals the change mechanisms of egg white properties during different storage periods and provides guidance for the processing of egg products. [ABSTRACT FROM AUTHOR]

The effects of ultrasonic treatment (180 W, 25 min) on the foaming and physicochemical properties of egg white from shell egg stored for seven periods (0, 15, 30, 45, 60, 75 and 90 d) were investigated in this study. The foaming ability significantly increased after ultrasound treatment and the highest foaming ability (99.13%) was achieved at 60 d compared to untreated egg white (29.75%). This improvement was ascribed to the increased free sulfhydryl content and surface hydrophobicity, indicating that egg white protein became easier to adsorb at the air-water interface and its structure was more flexible. However, a reduction in the foaming stability of ultrasound-treated egg white resulted from the lower absolute zeta potential. Moreover, decreasing particle size and broadening protein size distribution were obtained after ultrasonic processing. Using scanning electron microscopy, small aggregates were observed on the surface of the untreated sample after storage, while the ultrasound-treated sample had large numbers of irregular and unevenly distributed pores with different sizes. These results provide important evidence of the protein properties induced by ultrasound modification during storage, and further expand the ultrasound application in the food storage industry. • The highest foaming ability (99.13%) was achieved at 60 d by ultrasound modification. • Surface hydrophobicity and sulfhydryl content increased by ultrasound treatment. • Ultrasound decreased the absolute zeta potential of cold stored egg white. • Ultrasound decreased particle size and broadened size distribution of egg white. • Scanning electron microscopy showed irregular and unevenly distributed pore structure after ultrasound. [ABSTRACT FROM AUTHOR]