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Marc Hendrickx - One of the best experts on this subject based on the ideXlab platform.
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Foaming properties of Egg White proteins affected by heat or high pressure treatment
2007Co-Authors: Iesel Van Der Plancken, Ann Van Loey, Marc HendrickxAbstract:Abstract This paper deals with the effect of heat (50–85 °C) and high pressure treatment (400–700 MPa at 10–60 °C) on the foaming properties of Egg White solutions (10% v/v or 9.64 mg protein/mL). These physical treatments (20 min) were performed at two pH levels: pH 7.6 corresponding to the pH of fresh Egg White and pH 8.8, corresponding to that of older Egg White. Both heat and pressure treatment affected the foaming properties of Egg White proteins. While foams from untreated Egg White solutions were crispy and subject to collapse of the foam column after a long standing period, foams from heat and pressure-treated Egg White solutions were moist and creamy, showing smaller bubble size and little or no sensitivity to foam collapse. The effect of physical treatments was strongly dependent on the pH during treatment. The most voluminous foams were obtained at pH 8.8, while the most stable, dense foams were obtained at pH 7.6, for both heat and pressure treatment. Based on previous data on the effect of heat and pressure treatment on the physicochemical properties of Egg White proteins, the relationship between the processing-induced changes in these physicochemical properties and the foaming properties of Egg White was investigated. Treatments resulting in a high level of protein unfolding, yet accompanied by a certain degree of residual protein solubility (primarily at pH 8.8), resulted in Egg White solutions with improved foaming ability. A high level of unfolding combined with extensive protein solubility loss (primarily at pH 7.6) was associated with increased foam stability and density. Foams with high volume and average stability and density were obtained by pressure treatment at pH 8.8 (above 500 MPa). The processing-induced changes in the foaming properties could not be attributed to the changes in a single physicochemical property. The foaming ability was in part determined by the sulfhydryl content and protein flexibility. Improved protein–protein interactions (solubility and exposed SH groups) contributed to increased foam stability of treated Egg White solutions. Other properties, not measured in this study, probably also contribute to the foaming properties of processed Egg White solutions, especially after pressure treatment.
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changes in sulfhydryl content of Egg White proteins due to heat and pressure treatment
2005Co-Authors: Iesel Van Der Plancken, Ann Van Loey, Marc HendrickxAbstract:The sulfhydryl (SH) content of Egg White proteins (10% v/v or 9.64 mg of protein/mL) after heat (50-85 degrees C) and combined heat- and high-pressure treatments (100-700 MPa, 10-60 degrees C) was determined using 5',5-dithiobis (2-nitrobenzoic acid) (DTNB), both for the soluble fraction and the total protein fraction. Only irreversible changes were taken into account. Both physical treatments were performed at two pH levels: pH 7.6, corresponding to the pH of fresh Egg White, and pH 8.8, corresponding to that of aged Egg White. Both heat and combined heat- and high-pressure treatment resulted in an exposure of buried SH groups. These exposed SH groups were involved in the formation of disulfide bond stabilized protein aggregates, as shown by gel electrophoresis. Under severe processing conditions (above 70 degrees C at atmospheric pressure or above 500-600 MPa, depending on the temperature applied), a decrease in total SH content could be observed, probably due to the formation of disulfide bonds by oxidation, especially at alkaline pH when the thiolate anion was more reactive. The high degree of exposure of sulfhydryl groups, and subsequent oxidation and sulfhydryl-disulfide bond exchange reactions resulting in soluble aggregates, can explain why pressure-induced Egg White gels are softer and more elastic than heat-induced ones. When pressure treatment was performed at low temperatures (e.g., 10 degrees C), a lower pressure was required to induce similar changes in the sulfhydryl content, as compared to higher temperatures (e.g., 25 degrees C), indicating an antagonistic effect between pressure and temperature in the domain studied (10-60 degrees C, 100-700 MPa). Treatment conditions resulting in extensive protein insolubilization were accompanied by a transfer of free sulfhydryl groups from the soluble to the insoluble protein fraction. These SH groups were mainly accessible to DTNB.
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combined effect of high pressure and temperature on selected properties of Egg White proteins
2005Co-Authors: Iesel Van Der Plancken, Ann Van Loey, Marc HendrickxAbstract:Abstract A study was conducted on the effect of pressure at different temperature (10, 25, and 60 °C) and pH (7.6 and 8.8) levels on selected properties of Egg White solutions (turbidity, solubility, residual denaturation enthalpy, surface hydrophobicity, sulfhydryl content, susceptibility to enzymatic hydrolysis and trypsin inhibition activity). The pressure-induced changes in these properties were dependent on the pressure and temperature applied and the pH. The most pronounced changes were observed in the pressure range of 400–700 MPa. Pressure induced an increase in turbidity, surface hydrophobicity, exposed SH content and susceptibility to enzymatic hydrolysis, while it resulted in a decrease in protein solubility, total SH content, denaturation enthalpy and trypsin inhibitory activity. Industrial relevance Egg White is a multifunctional food ingredient with unique properties. Since pressure can induce changes in protein functionality it is of industrial relevance to explore the impact of pressure at different temperatures on Egg White properties. Pressure induced changes were pronounced and also dependent on pH and temperature thus offering the potential for a wide range of p, T and pH combinations for monitoring of unique Egg White protein functionality.
Francoise Nau - One of the best experts on this subject based on the ideXlab platform.
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The Role of Ovotransferrin in Egg-White Antimicrobial Activity: A Review
2021Co-Authors: Julie Legros, Francoise Nau, Sylvie Bonnassie, Sophie Jan, Thomas Croguennec, Michel Gautier, Stéphane Pezennec, Marie-françoise Cochet, Simon Andrews, Florence BaronAbstract:Eggs are a whole food which affordably support human nutritional requirements worldwide. Eggs strongly resist bacterial infection due to an arsenal of defensive systems, many of which reside in the Egg White. However, despite improved control of Egg production and distribution, Eggs remain a vehicle for foodborne transmission of Salmonella enterica serovar Enteritidis, which continues to represent a major public health challenge. It is generally accepted that iron deficiency, mediated by the iron-chelating properties of the Egg-White protein ovotransferrin, has a key role in inhibiting infection of Eggs by Salmonella. Ovotransferrin has an additional antibacterial activity beyond iron-chelation, which appears to depend on direct interaction with the bacterial cell surface, resulting in membrane perturbation. Current understanding of the antibacterial role of ovotransferrin is limited by a failure to fully consider its activity within the natural context of the Egg White, where a series relevant environmental factors (such as alkalinity, high viscosity, ionic composition, and Egg White protein interactions) may exert significant influence on ovotransferrin activity. This review provides an overview of what is known and what remains to be determined regarding the antimicrobial activity of ovotransferrin in Egg White, and thus enhances understanding of Egg safety through improved insight of this key antimicrobial component of Eggs.
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Characterization of Egg White gel microstructure and its relationship with pepsin diffusivity
2020Co-Authors: Geeshani Somaratne, Francoise Nau, Jaspreet Singh, Maria J. Ferrua, Didier Dupont, R. Paul Singh, Juliane FlouryAbstract:Understanding the diffusion of digestive enzymes, particularly pepsin, in different food structures, is a key factor to better control protein digestion and absorption. This study aimed to investigate how protein-based food microstructure impacts pepsin diffusion. Two Egg White gels (EWGs) of identical protein concentration (10%) but different structures were used as food models. The two different gel structures were prepared by heating liquid Egg White at pH5 and pH9, respectively. Results showed that Egg White proteins formed a compact and microstructurally homogeneous gel at pH9 (mean particle size of 0.32 ± 0.02 μm, with a mean interparticle distance of 0.76 ± 0.07 μm), which leads to a lower FITC-pepsin diffusion coefficient (Deff=44.2 ± 6.1 μm2 s−1), compared to the pH5-EWG (Deff=52.5 ± 5.3 μm2 s−1). The microstructure of the pH5-EWG was characterised by a spatially heterogeneous loose protein matrix made of larger aggregate particles (mean particle size of 0.76 ± 0.07 μm, with a mean interparticle distance of 1.79 ± 0.57 μm). In addition to the effects of the EWG microstructure, the environmental pH also affects the FITC-pepsin diffusion, likely because of the impact on electrostatic interactions between pepsin and the Egg White proteins.
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The anti-bacterial iron-restriction defence mechanisms of Egg White; the potential role of three lipocalin-like proteins in resistance against Salmonella
2019Co-Authors: Louis Alex Julien, Francoise Nau, Florence Baron, Sylvie Bonnassie, Catherine Guérin-dubiard, Sophie Jan, Simon Colin AndrewsAbstract:Salmonella enterica serovar Enteritidis (SE) is the most frequently-detected Salmonella in foodborne outbreaks in the European Union. Among such outbreaks, Egg and Egg products were identified as the most common vehicles of infection. Possibly, the major antibacterial property of Egg White is iron restriction, which results from the presence of the ironbinding protein, ovotransferrin. To circumvent iron restriction, SE synthesise catecholate siderophores (i.e. enterobactin and salmochelin) that can chelate iron from host iron-binding proteins. Here, we highlight the role of lipocalin-like proteins found in Egg White that could enhance Egg-White iron restriction through sequestration of certain siderophores, including enterobactin. Indeed, it is now apparent that the Egg-White lipocalin, Ex-FABP, can inhibit bacterial growth via its siderophore-binding capacity in vitro. However, it remains unclear whether Ex-FABP performs such a function in Egg White or during bird infection. Regarding the two other lipocalins of Egg White (Cal-c and a-1-glycoprotein), there is currently no evidence to indicate that they sequester siderophores.
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Egg White drying: Influence of industrial processing steps on protein structure and functionalities
2007Co-Authors: Valérie Lechevalier-datin, Romain Jeantet, Abdellah Arhaliass, Jacques Legrand, Francoise NauAbstract:Spray-dried Egg White is commonly used as a food ingredient for its foaming and gelling properties. However, these properties are obtained thanks to dry-heating of Egg White powder, which is necessary to offset the harmful effects of spray-drying process on Egg White functionality. The purpose of the present work is to identify the processing steps responsible for the damages to Egg White functional properties, and to understand the mechanisms that occur in order to limit these effects and to reduce dry-heating time. Two trials were performed and the measurements of Egg White protein conformation and gel firmness were significantly different from one trial to another, thus emphasizing great variations in raw material characteristics. In spite of this trial effect, processing steps significantly modified Egg White foaming properties. The most critical step was the spray-drying one that strongly damaged foaming properties. During this step, heat transfers and air–product interface area rather than shear rates were responsible for these changes. Then, it was the pumping and filtering steps that had also a considerable effect, due to the generation of shear rates and stainless steel–product interfaces, responsible for foaming property damages. On the other hand, concentration and desugarization steps had an interesting improving effect on Egg White foaming properties.
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Proteomic analysis of hen Egg White
2006Co-Authors: Catherine Guérin-dubiard, Maryvonne Pasco, Thomas Croguennec, Daniel Mollé, Colette Désert, Francoise NauAbstract:Hen Egg White is an original biological fluid in which major proteins have been widely studied, unlike the minor components. In this study, two-dimensional electrophoresis associated with mass spectrometry enabled the separation of 69 protein spots and their matching with major proteins, which were already known, and with minor proteins. Sixteen proteins were identified, and among them, two had never been previously detected in hen Egg White, i.e., Tenp, a protein with strong homology with a bacterial permeability-increasing protein family (BPI), and VMO-1, an outer layer vitelline membrane protein. Thirteen proteins present a very wide polymorphism (ovotransferrin, ovomucoid, clusterin, etc.), some of them up to nine isoforms (ovoinhibitor). Eleven functional protein families were identified (serpin, transferrin, protease inhibitors Kazal, glycosyl hydrolases, lipocalin, bactericidal permeability-increasing protein, clusterin, UPAR/CD59/Ly6/ snake neurotoxin, cysteine protease inhibitor, VMO-1, and folate receptor families). These various biological functions could be interesting for further valorizations. In addition, three spots remain unidentified, probably because these proteins are not yet indexed in the international protein databanks.
Catherine Guérin-dubiard - One of the best experts on this subject based on the ideXlab platform.
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The anti-bacterial iron-restriction defence mechanisms of Egg White; the potential role of three lipocalin-like proteins in resistance against Salmonella
2019Co-Authors: Louis Alex Julien, Francoise Nau, Florence Baron, Sylvie Bonnassie, Catherine Guérin-dubiard, Sophie Jan, Simon Colin AndrewsAbstract:Salmonella enterica serovar Enteritidis (SE) is the most frequently-detected Salmonella in foodborne outbreaks in the European Union. Among such outbreaks, Egg and Egg products were identified as the most common vehicles of infection. Possibly, the major antibacterial property of Egg White is iron restriction, which results from the presence of the ironbinding protein, ovotransferrin. To circumvent iron restriction, SE synthesise catecholate siderophores (i.e. enterobactin and salmochelin) that can chelate iron from host iron-binding proteins. Here, we highlight the role of lipocalin-like proteins found in Egg White that could enhance Egg-White iron restriction through sequestration of certain siderophores, including enterobactin. Indeed, it is now apparent that the Egg-White lipocalin, Ex-FABP, can inhibit bacterial growth via its siderophore-binding capacity in vitro. However, it remains unclear whether Ex-FABP performs such a function in Egg White or during bird infection. Regarding the two other lipocalins of Egg White (Cal-c and a-1-glycoprotein), there is currently no evidence to indicate that they sequester siderophores.
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Proteomic analysis of hen Egg White
2006Co-Authors: Catherine Guérin-dubiard, Maryvonne Pasco, Thomas Croguennec, Daniel Mollé, Colette Désert, Francoise NauAbstract:Hen Egg White is an original biological fluid in which major proteins have been widely studied, unlike the minor components. In this study, two-dimensional electrophoresis associated with mass spectrometry enabled the separation of 69 protein spots and their matching with major proteins, which were already known, and with minor proteins. Sixteen proteins were identified, and among them, two had never been previously detected in hen Egg White, i.e., Tenp, a protein with strong homology with a bacterial permeability-increasing protein family (BPI), and VMO-1, an outer layer vitelline membrane protein. Thirteen proteins present a very wide polymorphism (ovotransferrin, ovomucoid, clusterin, etc.), some of them up to nine isoforms (ovoinhibitor). Eleven functional protein families were identified (serpin, transferrin, protease inhibitors Kazal, glycosyl hydrolases, lipocalin, bactericidal permeability-increasing protein, clusterin, UPAR/CD59/Ly6/ snake neurotoxin, cysteine protease inhibitor, VMO-1, and folate receptor families). These various biological functions could be interesting for further valorizations. In addition, three spots remain unidentified, probably because these proteins are not yet indexed in the international protein databanks.
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Hen Egg White fractionation by ion-exchange chromatography
2005Co-Authors: Catherine Guérin-dubiard, Francoise Nau, Maryvonne Pasco, A. Hietanen, A. Quiros Del Bosque, Thomas CroguennecAbstract:Major hen Egg White proteins have been widely studied for their functional properties but these studies still are unable to explain, alone, all of the biological properties of hen Egg White. Hence, it is still interesting to produce pure and non-altered proteins to improve our knowledge on the biological properties of hen Egg White. Presently, identification and characterization of both bioactive peptides and minor proteins from hen Egg White is essential work for progressing in the understanding of hen Egg White biological properties. With this objective in mind, a new process for a complete "mucin free" hen Egg White fractionation based on ion exchange chromatography is proposed. "Mucin free" Egg White is fractionated into six different fractions. Four of them are high-recovery yield purified fractions of lysozyme, ovotransferrin, ovalbumin and flavoprotein. The two other fractions are enriched in recently detected minor proteins in hen Egg White.
Thomas Croguennec - One of the best experts on this subject based on the ideXlab platform.
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The Role of Ovotransferrin in Egg-White Antimicrobial Activity: A Review
2021Co-Authors: Julie Legros, Francoise Nau, Sylvie Bonnassie, Sophie Jan, Thomas Croguennec, Michel Gautier, Stéphane Pezennec, Marie-françoise Cochet, Simon Andrews, Florence BaronAbstract:Eggs are a whole food which affordably support human nutritional requirements worldwide. Eggs strongly resist bacterial infection due to an arsenal of defensive systems, many of which reside in the Egg White. However, despite improved control of Egg production and distribution, Eggs remain a vehicle for foodborne transmission of Salmonella enterica serovar Enteritidis, which continues to represent a major public health challenge. It is generally accepted that iron deficiency, mediated by the iron-chelating properties of the Egg-White protein ovotransferrin, has a key role in inhibiting infection of Eggs by Salmonella. Ovotransferrin has an additional antibacterial activity beyond iron-chelation, which appears to depend on direct interaction with the bacterial cell surface, resulting in membrane perturbation. Current understanding of the antibacterial role of ovotransferrin is limited by a failure to fully consider its activity within the natural context of the Egg White, where a series relevant environmental factors (such as alkalinity, high viscosity, ionic composition, and Egg White protein interactions) may exert significant influence on ovotransferrin activity. This review provides an overview of what is known and what remains to be determined regarding the antimicrobial activity of ovotransferrin in Egg White, and thus enhances understanding of Egg safety through improved insight of this key antimicrobial component of Eggs.
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Proteomic analysis of hen Egg White
2006Co-Authors: Catherine Guérin-dubiard, Maryvonne Pasco, Thomas Croguennec, Daniel Mollé, Colette Désert, Francoise NauAbstract:Hen Egg White is an original biological fluid in which major proteins have been widely studied, unlike the minor components. In this study, two-dimensional electrophoresis associated with mass spectrometry enabled the separation of 69 protein spots and their matching with major proteins, which were already known, and with minor proteins. Sixteen proteins were identified, and among them, two had never been previously detected in hen Egg White, i.e., Tenp, a protein with strong homology with a bacterial permeability-increasing protein family (BPI), and VMO-1, an outer layer vitelline membrane protein. Thirteen proteins present a very wide polymorphism (ovotransferrin, ovomucoid, clusterin, etc.), some of them up to nine isoforms (ovoinhibitor). Eleven functional protein families were identified (serpin, transferrin, protease inhibitors Kazal, glycosyl hydrolases, lipocalin, bactericidal permeability-increasing protein, clusterin, UPAR/CD59/Ly6/ snake neurotoxin, cysteine protease inhibitor, VMO-1, and folate receptor families). These various biological functions could be interesting for further valorizations. In addition, three spots remain unidentified, probably because these proteins are not yet indexed in the international protein databanks.
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Hen Egg White fractionation by ion-exchange chromatography
2005Co-Authors: Catherine Guérin-dubiard, Francoise Nau, Maryvonne Pasco, A. Hietanen, A. Quiros Del Bosque, Thomas CroguennecAbstract:Major hen Egg White proteins have been widely studied for their functional properties but these studies still are unable to explain, alone, all of the biological properties of hen Egg White. Hence, it is still interesting to produce pure and non-altered proteins to improve our knowledge on the biological properties of hen Egg White. Presently, identification and characterization of both bioactive peptides and minor proteins from hen Egg White is essential work for progressing in the understanding of hen Egg White biological properties. With this objective in mind, a new process for a complete "mucin free" hen Egg White fractionation based on ion exchange chromatography is proposed. "Mucin free" Egg White is fractionated into six different fractions. Four of them are high-recovery yield purified fractions of lysozyme, ovotransferrin, ovalbumin and flavoprotein. The two other fractions are enriched in recently detected minor proteins in hen Egg White.
Kenji Watanabe - One of the best experts on this subject based on the ideXlab platform.
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inhibiting effects of Egg White dry heated at 120 c on heat aggregation and coagulation of Egg White and characteristics of dry heated Egg White
1999Co-Authors: Kenji Watanabe, Jin-quan Xu, Makoto ShimoyamadaAbstract:Dialyzed and freeze-dried Egg White (FDEW) was dry-heated at 120 °C for up to 6 h. The inhibiting effects of the dry-heated Egg White (DHEW) on the heat aggregation and coagulation of Egg White (as 10% FDEW solution) and characteristics of the DHEW were examined. From the changes in turbidities and soluble protein contents of supernatant in various mixtures of 10% FDEW and DHEW solutions induced by heating (60 °C, 5 min), it was found that the inhibiting capacity increased with increases in the dry-heating time (DHT). The FDEW proteins were denatured with a mild conformational change (not secondary but tertiary structure) with the increase in DHT and aggregated partially. However, the more transparent solutions of DHEW containing soluble aggregates according to DHT were also obtained after heating. The transparency according to DHT came to be scarcely affected by the NaCl concentration and the dilution with diluents containing SDS, urea, and 2-mercaptoethanol. These findings suggest that the heat aggregat...
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heat aggregation of dry heated Egg White and its inhibiting effect on heat coagulation of fresh Egg White
1998Co-Authors: Jin-quan Xu, Makoto Shimoyamada, Kenji WatanabeAbstract:The characteristics of dialyzed and freeze-dried Egg White that was dry-heated under various conditions (70−125 °C, 0 min−6 h) were studied. The dry-heated Egg Whites (DHEWs, 120 °C) showed the formation of insoluble aggregates (coagula) within 50 min, turbid soluble ones (50 min−2 h), and transparent soluble ones (2−6 h) according to the dry-heating times when solubilized at 10% concentration (pH 7.4) and reheated at 60 °C for 3.5 min. A transparent DHEW solution without any coagula when reheated was obtained by using a shorter dry-heating time and elevating the dry-heating temperature. It was also found that NaCl suppressed the turbidity development of DHEW solution promoted by CaCl2. When 10% DHEW solutions (120 °C, >2 h) were mixed with fresh Egg White at the ratio of 1:1 in volume and heated at 60 °C for 3.5 min, coagulum formations in their mixtures were inhibited. The patterns of native− and SDS−PAGEs and gel filtration suggest that soluble aggregates of ovalbumin formed in the dry-heating process ...
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heat aggregation of dry heated Egg White and its inhibiting effect on heat coagulation of fresh Egg White
1998Co-Authors: Jin-quan Xu, Makoto Shimoyamada, Kenji WatanabeAbstract:The characteristics of dialyzed and freeze-dried Egg White that was dry-heated under various conditions (70−125 °C, 0 min−6 h) were studied. The dry-heated Egg Whites (DHEWs, 120 °C) showed the formation of insoluble aggregates (coagula) within 50 min, turbid soluble ones (50 min−2 h), and transparent soluble ones (2−6 h) according to the dry-heating times when solubilized at 10% concentration (pH 7.4) and reheated at 60 °C for 3.5 min. A transparent DHEW solution without any coagula when reheated was obtained by using a shorter dry-heating time and elevating the dry-heating temperature. It was also found that NaCl suppressed the turbidity development of DHEW solution promoted by CaCl2. When 10% DHEW solutions (120 °C, >2 h) were mixed with fresh Egg White at the ratio of 1:1 in volume and heated at 60 °C for 3.5 min, coagulum formations in their mixtures were inhibited. The patterns of native− and SDS−PAGEs and gel filtration suggest that soluble aggregates of ovalbumin formed in the dry-heating process ...