Duck Egg White Research Articles

Foam-Mat Drying Process of Duck Egg White

The foam-mat dryingprocessof egg white, developed in the food industry, promotes a porous product, brittle and easy to grind. The powderedegg white has a good rehydration properties, safer consumption and storage conditions than fresh product, keeping the high level of proteins and vitamins contained in the egg. In this way, the objective of this work is to study, through numerical computational simulation, the physical aspects of the duck egg white foam-matdrying process. For this, the foam was characterized by its density, percentage of expansion, air over run, stability and moisture. Temperature (50, 60 and 70°C), stirring rate (levels 6, 7 and 8) and stirring time (4, 5 and 6 minutes) are taken as input conditions and the product final moisture and drying time are the output variables. Drying was performed based on the complete factorial 23 + 3 central point experimental design in this procedure. It has been observed that the time and stirring rate significantly influence the product final moisture and that the drying temperature is predominant for the total process time. From the foam moisturedata, adjustments of empirical mathematical models were made; evidencing that theModifiedPage and the Page models provided the best results, with a standard deviation lower than 0.01 and the coefficient of determination above 0.99. For this analysis, the case where the drying temperature, time and the stirring rate were, respectively, 70 °C, 6 minutes and 8 level, presented the best results.

Advances on Comprehensive Utilization of Salted Duck Egg White

Salted duck egg white is a by-product of duck egg processing and high-quality proteins with high nutritional value and good processing properties.However a large amount of salted duck egg white is discarded every year,resulting in a waste of egg resources and polluting the environment at the same time. And only a small amount of salted duck egg white is added to the feed currently.The research of salted duck egg white is summarized in this paper,and aims to provide a reference and theoretical basis for the high value utilization of salted duck egg white,leading to be a useful reference for the reuse of salted duck egg white.

Duck Egg White-Derived Peptide VSEE (Val-Ser-Glu-Glu) Regulates Bone and Lipid Metabolisms by Wnt/β-Catenin Signaling Pathway and Intestinal Microbiota.

Val-Ser-Glu-Glu (VSEE), identified from duck egg white peptides, has been proven to facilitate calcium absorption in a previous study. Since prevention of osteoporosis is important, it might act as a potential cofactor in osteoporosis prevention. Therefore, the aim of this study is to investigate the regulation of VSEE on osteoporosis and abnormal lipid metabolisms. MC3T3-E1 cell and ovariectomized (OVX) rat model are used to evaluate VSEE on regulation of bone and lipid metabolisms. Differentiation and matrix mineralization of preosteoblast are significantly increased by VSEE (p <0.05), which attributed to stimulating calcium influx, then to activating Wnt/β-catenin signaling pathway and regulating runt-related transcription factor 2 and osteoprotegerin. VSEE can cross Caco-2/HT-29 co-cultured monolayer via paracellular pathway and peptide transporter 1 (PepT1), and can be detected in blood and maximum concentration is 122.84 ± 3.68 mg L-1 at 60 min. Additionally, VSEE reverses bone loss and regulate dyslipidemia through Wnt/β-catenin signaling pathway in OVX rats. Firmicutes phylum, Veillonellaceae, Prevotellaceae and six genera in VSEE group are significantly different compared with the Model group (p < 0.05). VSEE promotes bone growth and inhibit abnormal lipid metabolism in an OVX model through the regulation of intestinal microbiota compositions and Wnt/β-catenin signal pathway.

Salt-tolerant Staphylococcus bacteria induce structural and nutritional alterations of salted duck egg white.

Salted duck egg white, a major by‐product of salted egg yolk production, is rich in nutrients. However, its high salinity limits its application in the food industry. In the present study, three haloduric bacterium strains (C1, C2, and C3) were isolated from Jinhua ham, and strain C1 exhibited higher ratio of the transparent circle diameter to the colony diameter (HC) and gelatin liquefaction. Strain C1 was further identified as a member of the genus Staphylococcus through gene sequencing and EzTaxon‐e analyses. Salted duck egg white was fermented by strain C1, and the thermal stability, microstructure, amino acid composition, and γ‐aminobutyric acid of the egg white were compared with egg white without fermentation. The fermented salted duck egg white had a significantly low salinity. Meanwhile, it increased its thermal stability compared with the control through losing an endotherm at around 85°C and forming a new endotherm peak starting at 91.8°C. Additionally, free amino acids and γ‐aminobutyric acid were found only in the fermented salted duck egg white. These indicated that fermentation with salt‐resistant strains could alter the structure of salted duck egg white and improve its nutritional quality.

Identification of the Duck Egg White N-Glycoproteome and Insight into the Course of Biological Evolution

Protein glycosylation is a ubiquitous posttranslational modification that modulates protein properties, thereby influencing bioactivities within a system. Duck egg white (DEW) proteins exhibit diverse biological properties compared with their chicken egg white (CEW) counterparts, which might be related to glycosylation. N-Glycoproteome analysis of DEW was conducted, and a total of 231 N-glycosites from 68 N-glycoproteins were identified. Gene ontology analysis was used to elucidate the biofunctions of DEW N-glycoproteins and compare them with those of CEW, which showed that the differences mostly involved molecular functions and biological processes. The biological functions of DEW N-glycoproteins were illuminated through bioinformatics analysis and comparison with CEW orthologues, which showed different allergenicities and antibacterial abilities. These divergences might be initiated by specific alterations in glycosylation, which can enhance the proteolysis resistance and protein steric hindrance. These results provide new insights for discovering the effects of N-glycosylation on biofunctions during the divergence of homologous proteins.

Assessment of different proteases on degree of hydrolysis, functional properties and radical scavenging activities of salted duck egg white hydrolysate.

The impact of different proteases (alcalase, ficin, protamex, and neutrase) on the hydrolyzation, foaming and radical scavenging potency of salted duck egg white was studied. Egg white without protease hydrolyzation served as control. Regarding the degree of hydrolysis, neutrase and protamex were more capable of hydrolyzing duck egg white than the others. The α-amino nitrogen content in the egg whites was highly correlated with hydrolysis ability of the enzymes, and it had gradually increased with curing. Foam stability, capacity and emulsion stability were significantly influenced by proteases and curing period. However, the solubility of the egg white hydrolysate was not much affected by curing but showed significant differences between hydrolyzed and control samples. Emulsion stability of hydrolysate decreased with curing times. Neutrase and alcalase hydrolysates gave the best foaming and emulsion properties. Moreover, neutrase and protamex hydrolysates showed good scavenging potency against the DPPH radicals, hydroxyl radicals, hydrogen peroxide, and ferrous ion radicals. Overall, the hydrolysate from neutrase hydrolyzed duck egg white showed the highest foaming and radical scavenging capacities among the other hydrolysis treatments in this study.

Production of protein powder from salted duck eggs white

The objective of the research was to determine process conditions to produce protein powder from salted duck egg whites based on the two main steps including precipitation of the protein from egg white and drying the protein. Optimization for process parameters of protein's precipitation and drying were carried out by Response Surface Design method with the results obtained from the experiment. Basing on the determination of the limits of studied factors, defining the regression and choosing the optimal parameters for precipitation and drying processes. The result of optimal protein precipitation was the ratio of water/salted duck egg white: 3.5/1, the temperature of 80oC and precipitation time of 60 minutes with the process yield was 9.63% and the salt separation was 19.61%. The result of optimal drying process was the drying temperature at 75oC, material density: 0.35 g/cm2 (wind speed of 0.64 m/s and drying time of 4 h) with the product solubility of 11.05%, the water content of 8.19% and aw of 0,476. Verifying the defined regression equation and experiment showed the different level is less than 5%, the defined regression equation is valid and has the potential to apply in production.

Influence of Prolonged Salting on the Physicochemical Properties of Duck Egg White

ABSTRACT Salted duck eggs are unique among the important authentic foods of Thailand. They are mainly produced in Chaiya district, Surat Thani province, in the southern part of Thailand. The egg whites of salted duck eggs are normally unusable due to heavily salty taste upon prolonged storage. The present study was aimed to examine the foaming characteristics of egg white after being cured for a prolonged period (30 days). At 5-day intervals the egg whites were measured for salt, moisture, water activity, hydrophobicity, pH, zeta potential, particle size, SH groups, surface tension and foaming properties (index of whipping, foam durability, specific density, overrun, air phase and yield stress). The results showed that prolonged curing significantly affected egg white and its foam. Salt content, hydrophobicity, particle size, and exposed SH groups gradually increased with storage period. On the other hand, moisture, water activity, pH, zeta potential, surface tension and total SH groups decreased continuously throughout the storage. In addition, foaming properties slightly declined due to accumulation of salt content with extended storage. Conversely, the yield stress - an important indicator of foam quality - increased from 32.33 to 70.55 % during storage. Overall, the egg whites could possibly serve as a key and/or a substitute ingredient in foam-based food products.

DUCK EGGWHITE POTENTIAL IN TREATING SUBACUTE LEAD POISONING

Objectives: The aim of this research is to study duck eggwhite potential in treating subacute lead poisoning.Methods: The potential of duck egg white was evaluated from the red blood cell profile and the clinical signs that emerged. The research used thirtymale rats which were divided into 6 groups and 5 replications (i.e. rats as control, rats dministrated only with lead, rats administrated with leadand antidote). Each of the four treatment groups were given one antidote (i.e. EDTA, 50% egg white, 75% egg white, and 100% egg white). Leadforce feeding was conducted for 15 days, followed by the administration of the antidote for the same duration of 15 days, and concluded with bloodsampling at the end of each treatment.Results: There was no significant effect on haemoglobin but lead decreased total red blood cells (p&lt;0.05) in subacute lead poisoning. Rats that weregiven 75% and 100% duck egg white as an antidote showed an increase in total red blood cell counts in addition to a faster recovery.Conclusion: High concentration of duck egg white had shown positive results as an antidote for subacute lead poisoning.

Quality, Textural, and Sensory Properties of Yellow Alkaline Noodles Formulated with Salted Duck Egg White

AbstractThe objective of this study was to utilize salted duck egg white as an alternative source of salt for yellow alkaline noodles (YAN). YAN with salted duck egg white (YAN‐EW) was formulated by incorporating 15.21 g of salted duck egg white to replace the 1 g of salt. The effects of this substitution on the proximate compositions, physicochemical properties, cooking properties, textural properties and organoleptic properties of YAN were determined. YAN‐EW showed to have significantly higher (P &lt; 0.05) protein content, lighter and more yellowish compared to control YAN‐C. No significant difference between YAN‐EW and YAN‐C in terms of pH and cooking properties. YAN‐EW exhibited similar hardness and springiness as YAN‐C, but have significantly higher (P &lt; 0.05) cohesiveness and chewiness. YAN‐EW received scores on a par with YAN‐C in all sensory attributes. All the sensory attributes scored higher than 5, indicating good acceptance of YAN‐EW by the sensory panelists.Practical ApplicationsHigh demand on traditional Chinese foods, such as mooncakes and glutinous rice dumplings, generated a large amount of waste, i.e., salted duck egg white. Potential use of salted duck egg white as a food ingredient is of great interest to the industry. The present work describes the use of salted duck egg white in yellow alkaline noodle. The main finding is that salted duck egg white showed potential to be utilized as an alternative source to table salt in noodle formulation. This information can be useful to noodle producers in utilizing “waste” as a natural source of salt.

Physicochemical and nutritional characteristics of preserved duck egg white

In this paper, the physicochemical and nutritional characteristics of preserved duck egg white were analyzed and compared with fresh egg and hard-cooked egg white (n = 3). The data obtained showed that the preserved egg white was rich in essential amino acids and minerals, such as Ca, Mg, Fe, Zn, Cu, K, and Na. After fresh duck eggs were processed into preserved eggs, contents of moisture, CP, amino acid, and water-soluble vitamin of egg white significantly decreased (P < 0.05); however, pH, free amino acid content, and most inorganic elemental contents of egg white significantly increased (P < 0.05). The preserved egg white had higher a* (redness/greenness) and b* values (yellowness/blueness; P < 0.05) and lower L* value (lightness; P < 0.05) than hard-cooked egg white. The gel hardness of preserved egg white was approximately 50% of hard-cooked egg white; however, its springiness and cohesiveness were approximately 1.5 times of hard-cooked egg white. The results indicated that pickling with alkaline and other additives can significantly change physical properties and chemical composition of duck egg white, which make preserved egg white with characteristics of rich elements, brown color, and high springiness, but low vitamin.

Multiple Biological Functions of Novel Basic Proteins Isolated from Duck Egg White: Duck Basic Protein Small 1 (dBPS1) and 2 (dBPS2)

Biological functions of duck basic protein small 1 (dBPS(1)) and 2 (dBPS(2)) were investigated by in vitro experiments. Results of agarose gel retardation assay indicated that dBPS(1) and dBPS(2) associate with RNA. Addition of NaCl or urea induced partial dissociation of dBPS(1)/dBPS(2)-RNA complex, implying that electrostatic interaction, hydrophobic interaction, and hydrogen bonds are involved in the association of dBPS(1)/dBPS(2) to RNA. dBPS(1) and dBPS(2) inhibited pancreatic lipase activity with the fifty percent inhibitory concentration (IC(50)) of 250 and 100 μg/mL, respectively. Peptic hydrolysates of dBPS(1) and those of dBPS(2) showed a potent angiotensin I-converting enzyme (ACE) inhibition with an IC(50) of 22.5 and 49.6 mg/L. The most potent ACE-inhibitory peptide was a nanopeptide (EKKGFCAGY) from dBPS(1) and an octapeptide (KYCPKVGY) from dBPS(2). These multiple biological functions of dBPS(1) and dBPS(2) may contribute to reducing the risk of lifestyle diseases.

Changes in physicochemical properties of egg white and yolk proteins from duck shell eggs due to hydrostatic pressure treatment

The shell of the duck egg did not crack after pressure treatments (300 to 500 MPa; 25 degrees C; 10 min) in this study; therefore, the changes of physicochemical properties of egg white and yolk proteins from the intact shell egg by pressure treatment were first investigated and compared with those of pressurized hen liquid eggs. Although the proximate compositions of duck eggs and hen eggs were similar, the moisture and protein contents of hen whole eggs were higher than those of duck whole eggs. The protein contents of duck egg white and yolk were slightly lower than those of hen eggs, and the moisture content of duck egg white was equal to that of hen egg white, whereas that of duck egg yolk was lower than that of hen egg yolk. After pressure treatment at 500 MPa, the results of solubility, sulfhydryl content, surface hydrophobicity, and residual denaturation enthalpy showed that egg white proteins underwent slight but significant unfolding and aggregation, whereas pressure treatments below 500 MPa induced insignificant changes in the physicochemical properties. On the other hand, pressure treatments at 400 and 500 MPa significantly reduced the solubility and residual denaturation enthalpy of egg yolk proteins. However, the native PAGE result showed that pressure treatment up to 500 MPa did not affect the protein components of egg white and yolk. The results showed that the application of pressure treatment on duck shell egg may induce reversible denaturation of both egg white and yolk proteins. The egg white and yolk proteins may be prevented from denaturation after pressure treatment in the presence of the eggshell compared with the absence of the eggshell. As reported in the literature, pressure treatments at 300 to 500 MPa and 25 degrees C would be efficient for decontamination of duck shell eggs. Therefore, based on the consideration for food safety and functional properties, pressure processing can be a good preservation technique for duck shell eggs.

Antioxidative Activities of Hydrolysates from Duck Egg White Using Enzymatic Hydrolysis

Duck egg white (DEW) hydrolysates were prepared by five enzymes (papain, trypsin, chymotrypsin, alcalase, and flavourzyme) and their antioxidant activities investigated in this study. DEW hydrolyzed with papain (DEWHP) had the highest peptide content among the five enzymatic treatments. Besides, the peptide content of DEWHP increased when the enzyme to substrate ratio (E/S ratio) increased. It was suggested that higher E/S ratio contributed to elevate the degree of hydrolysis of DEW effectively. Similar results were also obtained by Tricine-SDS-PAGE. In addition, SDS-PAGE patterns indicated papain was the only one amongst all enzymes with the ability to hydrolyze DEW. In antioxidant properties, DEWHP showed more than 70% of inhibitory activity on linoleic acid peroxidation and superoxide anion scavenging. Moreover, the Fe 2+ chelating effect of DEWHP was greater than 90%, while no significant difference was observed in DPPH radical scavenging and reducing ability. The results of peptide contents, antioxidant activities and electrophoresis suggested that the higher the peptide content, the stronger the antioxidant activities in DEWHP. (Key Words : Duck Egg White, Hydrolysis, Antioxidant Activities)

Protein Hydrolysate of Salted Duck Egg White as a Substitute of Phosphate and Its Effect on Quality of Pacific White Shrimp (Litopenaeus Vannamei)

Protein hydrolysate from salted egg white (PHSEW) with different degrees of hydrolysis (DH) (3%, 6%, and 9%) was produced using pepsin. Disappearance of proteins with molecular weight (MW) of 108 and 85 kDa with the concomitant formation of proteins with MW of 23, 20, 13, and 5 kDa was observed in PHSEW. The use of PHSEW for quality improvement of Pacific white shrimp (Litopenaeus vannamei) was investigated. Shrimp soaked in 4% NaCl containing 7% PHSEW and 2.5% mixed phosphates (0.625% sodium acid pyrophosphate [SAPP] and 1.875% tetrasodium pyrophosphate [TSPP]) had the highest cooking yield with the lowest cooking loss (P < 0.05), compared with shrimps with other treatments. Nevertheless, no difference in weight gain was obtained in comparison with those treated with 4% NaCl containing 3.5% mixed phosphate (P > 0.05). Cooked shrimp treated with 4% NaCl containing 7% PHSEW and 2.5% mixed phosphate or those treated with 4% NaCl containing 3.5% mixed phosphate had the higher score of appearance, texture, and overall likeness but less shear force, in comparison with the control (no treatment) (P < 0.05). Microstructure study revealed that muscle fibers of cooked shrimp from both treatments had the swollen fibrils and gaps, while the control had the swollen compact structure. Therefore, use of PHSEW could reduce phosphate residue in shrimps without an adverse effect on sensory properties.

Structural and Physicochemical Characteristics of Novel Basic Proteins Isolated from Duck Egg White

Novel basic proteins, duck basic protein small 1 (dBPS(1)) and 2 (dBPS(2)), were isolated from duck egg white by cation-exchange and gel filtration chromatography. Protein sequence analyses indicated that they possessed 39 amino acid residues with three disulfide bonds. The amino acid sequence of dBPS(1) showed 45% identity with dBPS(2). The amino acid sequence of dBPS(2) was the same as cygnin, a small protein from black swan, and strongly homologous with meleagrin from turkey and chicken. Phylogenic relationships implied that dBPS(1) and dBPS(2) share a common ancestry with cygnin and meleagrin. Based on MALDI-TOF mass spectra, the molecular masses of dBPS(1) and dBPS(2) were 4,373, and the 4,486 Da. pI of dBPS(1) and dBPS(2) elucidated by isoelectric focusing were 9.35 and 9.44. FT-IR spectra classified these proteins as (beta) proteins. Both dBPS(1) and dBPS(2), possessed high heat stability, Td 101.2 and 98.3 degrees C. Indirect ELISA results showed that the dBPS(1)/dBPS(2)-related proteins were distributed in the oviduct and gallbladder.

Enhanced C‐Type Lysozyme Content of Wood Duck (Aix sponsa) Egg White: An Adaptation to Cavity Nesting?

Abstract Wild waterfowl species often nest in conditions where high humidity and microbial contamination may influence egg survival and quality. Albumen is traditionally regarded as the major impediment to microbial contamination of eggs, and its composition and activity may be selected by environmental pressures. Egg white protein from the eggs of wood duck (Aix sponsa), hooded merganser (Lophodytes cucullatus), Canada goose (Branta canadensis), and mute swan (Cygnus olor) was evaluated in order to compare the antimicrobial defenses of these species. Ovotransferrin and ovalbumin were identified in all species, but c-type lysozyme was present only in wood duck and hooded merganser egg white samples. Wood duck egg white showed the greatest bacterial activity as well as the highest lysozyme content. Egg white from wood duck and hooded merganser possessed greater lysozyme activity under acidic conditions, suggesting a c-type lysozyme with a pH optimum lower than that of Gallus gallus c-type lysozyme or the presence of g-type lysozyme. Ovotransferrin bacteriostatic activity appeared to be similar across the species investigated. The results suggest that lysozyme and ovotransferrin play a role in the antimicrobial defense of the avian egg. High levels of the broad-acting c-type lysozyme appear to have evolved in the albumen of the wood duck in order to ensure proper development of the embryo in the humid conditions of the cavity nest.

A novel human leukocyte elastase inhibitor from duck egg white

A serine proteinase inhibitor (ovomucoid) has been isolated from duck egg white. The duck ovomucoid effectively inhibited HLE, PPE, chymotrypsin, and HCG in a 1:1 molar ratio, and trypsin in a 1:2 molar ratio. Inhibition of human plasmin and porcine pancreatic kallikrein was not observed. The ovomucoid shows equilibrium dissociation constants of 0.002; 2.4; 2.2; 6.1; and 18.0 nM for HLE, PPE, chymotrypsin, trypsin, and HCG, respectively. The molecule of inhibitor can simultaneously bind two trypsin molecules and one molecule of elastase (or chymotrypsin).

Purification and characterization of cystatin from duck egg white.

It is the second peptidase inhibitor, after ovostatin, which showing the same antipapain activity in egg white in different avian species implies differences in amino-acid sequences. Cystatin from duck egg white was purified by carboxymethylpapain affinity chromatography and size-exclusion HPLC. The purified inhibitor which showed partial identity in the immunodiffusion test with chicken egg white cystatin, had an apparent molecular mass of 9.3 kDa as determined by SDS/PAGE. IEF analysis revealed five molecular forms of pI in the range 7.8-8.4. The obtained cystatin was neither glycosylated nor phosphorylated as it is in the case of chicken cystatin. The determined Ki (0.005 +/- 0.001 nM) was similar to that reported for human and chicken cystatin C.

Multiple Lysozymes of Duck Egg White

Abstract Lysozyme was purified from a pooled sample of Peking duck egg whites by ion exchange chromatography and gel filtration. Three different lysozymes were found, and each was shown to be pure by several criteria. The three enzymes were like chicken lysozyme in molecular size and specific activity, although they could be distinguished from it, as well as from one another, by electrophoretic and immunological criteria. The three duck enzymes were shown to be very similar to one another on the basis of amino acid composition (in particular, all lacked histidine) and immunological tests. Lysozyme was then partially purified from 44 individual duck egg whites and subjected to starch gel electrophoresis at pH 5.3, at which the three different lysozymes are readily distinguishable from each other. Each individual egg white contained either any one of the three lysozymes alone or a combination of any two of them. No single egg white contained all three duck lysozymes. The frequency of the six different phenotypes, as well as the marked similarity of the three enzymes to one another, leads us to suggest the existence of three alleles at one locus in the duck population which we examined.