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At least 19 recordsLinked to original sources
PubMed2000

Metabolites of oxytetracycline, tetracycline, and chlortetracycline and their distribution in egg white, egg yolk, and hen plasma.

4-epioxytetracycline and N-demethyloxytetracycline, as metabolites of oxytetracycline (OTC), 4-epitetracycline and N-demethyltetracycline, as metabolites of tetracycline (TC), and 4-epichlortetracycline, isochlortetracycline (ICTC), 4-epi-ICTC, and N-demethyl-ICTC, as metabolites of chlortetracycline (CTC), were detected in egg yolk and plasma obtained from feeding studies with either OTC, TC, or CTC. In egg white, only OTC, TC with its 4-epimer, and ICTC with its 4-epimer were detected in substantial concentrations. The ratios of epimerization and N-demethylation in the eggs did not change during the medication period. The samples were analyzed by an automated HPLC system (ASTED) with UV, fluorescence, or MS-MS detection.

Animals↗
PubMed2000

Automated residue analysis of tetracyclines and their metabolites in whole egg, egg white, egg yolk and hen's plasma utilizing a modified ASTED system.

An automated analytical method is described allowing simultaneous determination of all tetracyclines and metabolites in whole egg, egg yolk, egg white and blood plasma of the hens. Sample pretreatment is restricted to homogenization and a dilution step. Clean-up is by on-line dialysis and on-line solid-phase extraction utilizing an extended ASTED system, followed by liquid chromatography with UV or fluorescence detection with post-column pH adjustment and confirmational analysis by LC-MS-MS. After feeding oxytetracycline (OTC), tetracycline (TC) and chlortetracycline (CTC) to laying hens, not only residual parent compounds could be found in the eggs but also in vivo formed 4-epimers, isochlortetracycline (ICTC) and tentatively identified N-desmethyl metabolites of OTC, TC and ICTC.

Animals↗
PubMed1982

Purification and characterization of an acidic trypsin/subtilisin inhibitor from tortoise egg white.

Egg whites of three species of tortoise and turtle have been compared by gel chromatography for inhibitory activity against proteases. The egg white of Geomyda trijuga trijuga Schariggar contains trypsin/subtilisin inhibitor while the egg white of Caretta caretta Linn. contains both trypsin and chymotrypsin inhibitors. No protease inhibitory activity has been detected in the egg white of Trionyx gangeticus Cuvier. An acidic trypsin/subtilisin inhibitor has been purified to homogeneity from the egg white of tortoise (G. trijuga trijuga). It is a single polypeptide chain of 100 amino acid residues, having a molecular weight of 11,700. It contains six disulphide bonds and is devoid of methionine and carbohydrate moiety. Its isoelectric point is at pH 5.95 and is stable at 100 degrees C for 4 hr at neutral pH. The inhibitor inhibits both trypsin and subtilisin by forming enzyme-inhibitor complexes at a molar ratio close to unity. Their dissociation constants are 7.2 x 10(-9) M for bovine trypsin and 5.5 x 10(-7) M for subtilisin. Chemical modification of amino groups with trinitrobenzene sulfonate has reduced its inhibitory activities against both trypsin and subtilisin, but the loss of its trypsin inhibitory activity is faster than that of its subtilisin inhibitory activity. It has independent binding sites for inhibition of trypsin and subtilisin.

Amino Acids↗
PubMed1983

Gas-liquid chromatographic determination of trace amounts of nitrite in egg, egg white, and egg yolk.

A simple, sensitive, and practical method is described for determination of nitrite in egg, egg white, and egg yolk. Egg is deproteinized by adding a mixture of ammonium thiocyanate, mercuric chloride, and zinc acetate, and centrifuged. Nitrite in the supernate is converted to tetrazolophthalazine by reaction with hydralazine in acidic solution and then determined by gas-liquid chromatography with an electron-capture detector (GLC-ECD) and a column of OV-225 on Chromosorb W(HP). Nitrite concentrations from 5 to 50 ng/mL are calculated from peak height; the detection limit is 3 ng/mL extract. Recoveries from eggs, egg whites, and egg yolks ranged from 91.7 to 98.0%. The mean nitrite concentration in 50 egg samples was 0.04 ppm (0.01-0.11 ppm) with a detection limit of 4 ng nitrite/g.

Animals↗
PubMed1996

On hen egg fractionation: applications of liquid chromatography to the isolation and the purification of hen egg white and egg yolk proteins.

Liquid chromatography has been used as a means of egg protein analysis or as a method for the purification of egg proteins. Several chromatographic methods, including gel permeation, ion-exchange, reversed-phase, hydrophobic interaction, and immobilized-ligand-affinity chromatography, have been carried out for the separation or the purification of egg yolk or egg white proteins. Ion-exchange chromatography appears to be the most frequently used method for protein isolation and it is the easiest to adapt to a process scale. From an analytical point of view reversed-phase chromatography is, at the moment, the recommended method for egg white analysis. Egg white has been fractionated more often by liquid chromatography than has egg yolk. Several chromatographic methods have been developed on a laboratory scale, but the application of these techniques on an industrial scale remains limited.

Animals↗
PubMed1988

New allergens from hen's egg white and egg yolk. In vitro study of ovomucin, apovitellenin I and VI, and phosvitin.

Three hen egg yolk proteins, apovitellenins I and VI and phosvitin, and one egg white protein, ovomucin, were purified and tested for their ability to bind IgE in the sera of patients hypersensitive to egg. All of the proteins bound IgE from the sera of egg-allergic individuals in the radioallergosorbent test, and they also inhibited binding of IgE to the parent fractions-either egg yolk (apovitellenins I and VI and phosvitin) or egg white (ovomucin). It appears that apovitellenins I and VI are major allergens for some of the individuals tested. This is the first report of the in vitro allergenicity of these proteins.

Allergens↗
PubMed2003

A comparison of the buttermilk solids functional properties to nonfat dried milk, soy protein isolate, dried egg white, and egg yolk powders.

Physicochemical (i.e., sulfhydryl group, protein, and total solubility) as well as functional properties (i.e., water-holding and fat-absorption capacity, foaming and emulsification capacity, and stability) of commercial buttermilk solids (BMS) were compared to nonfat dried milk, soy protein isolate, and dried egg yolk and egg white powders on an equivalent protein basis. BMS showed limited functional properties in water-holding capacity (0.75 g water/g protein) and fat-absorption capacity (1.2 g of oil/g of protein), and foaming capacity (0.5 ml of foam/ml of solution) and stability. However, emulsifying capacity and stability of BMS was not significantly different from other dried protein powders. Results indicated that 0.9 g of protein (approximately 0.45%, wt/vol, concentration) from BMS was needed to emulsify a maximum oil concentration of 50% in water at temperatures up to 50 degrees C. Denaturation of protein, quantified by free sulfhydryl groups, was a critical factor affecting the functionality of BMS and all other protein powders tested. The milk fat globule membrane present in BMS did not enhance either emulsifying capacity or stability.

Adsorption↗
PubMedDate not supplied

[Dynamics of amino acid and protein metabolism of laying hens after the administration of 15N-labeled wheat protein. 3. Incorporation of 15N into egg shell, egg white and egg yolk].

12 colostomized laying hybrids received a ration meeting their requirement of 15N labelled wheat with a 15N excess (15N') of 14.37 atom-% over 4 days. The 15N' of the total ration amounted to 4.47 atom-%. Each hen consumed 135 mg 15N' per day. On another 4 days the same rations with non labelled wheat were fed. The 12 hens laid 56 eggs during the 8 days of the experiment. They were divided into egg shell, white and yolk of egg. In addition, the protein of the white and yolk of egg was precipitated with trichloric acetic acid (TCA) and the nitrogen in these fractions was determined. On average of the 56 eggs, the N quota in the egg shell was 5.3%, in the white of egg 49.1% and in the yolk 45.6%. The atom-% 15N' in the shells of the eggs laid on the first day of the experiment was on average 0.21, whereas only 0.03 and 0.02 atom-% 15N' resp. could be detected in the white and yolks of the eggs. On the first day after the last 15N application the atom-% 15N' in the egg shell and the white of egg was highest and amounted to 2.33 and 2.43 atom-% resp. The highest value of 1.83 atom-% 15N' in the yolk was ascertained 3 days after the last 15N intake. The mean quota of TCA-precipitable N in the white of egg is 97.6% and in the yolk 94.4% of the respective total N. The atom-% 15N' in the non-protein N-compounds was higher than in the protein fractions.

Amino Acids↗
PubMed1999

Rapid growth of Salmonella enteritidis in egg white reconstituted from industrial egg white powder.

The aim of this study was to evaluate the consequences of the egg white-drying process on egg white ability to limit Salmonella Enteritidis growth in addition to the elucidation of the factors involved. We observed rapid growth of Salmonella Enteritidis inoculated in egg white reconstituted from industrial powder in comparison with that observed in liquid egg white collected in the laboratory: Salmonella cell counts rose from 10(3) to 10(8) cells/ml of egg white from powder during 24 h incubation at 30 degrees C. This rapid growth was observed in powder from all egg-breaking factories investigated, and it was comparable to that observed in optimum medium (tryptone soy broth). In view of the mechanism of egg white resistance and the major role played by iron availability and by ovotransferrin, we investigated several hypotheses to explain this rapid growth: iron provided during the drying process and/or denaturation of protein (especially ovotransferrin). The rapid growth observed in egg white reconstituted from powder was in relation to egg white protein denaturation and especially ovotransferrin denaturation during powder pasteurization that enhanced the availability of iron necessary for Salmonella growth. The major role played by ovotransferrin and iron deficiency on Salmonella growth in egg white was illustrated in this study.

Animals↗
PubMed1983

A clinical and immunological study of allergy to hen's egg white. VI. Occurrence of proteins cross-reacting with allergens in hen's egg white as studied in egg white from turkey, duck, goose, seagull, and in hen egg yolk, and hen and chicken sera and flesh.

The occurrence of proteins cross-reacting with allergens in hen's egg white was studied in turkey, duck, goose and seagull egg whites, in hen egg yolk, and in hen and chicken sera and flesh. The study was based upon quantitative immunoelectrophoretic techniques. The different egg whites were all found to contain proteins cross-reacting with most of the allergens in hen's egg white, but the degree of cross-reactivity varied considerably among the various egg whites. All egg whites contained proteins able to bind human IgE-antibody in the sera of patients with allergy to hen's egg white. Several proteins cross-reacting with allergens in hen's egg white were also detected in egg yolk and in hen and chicken sera and flesh. Clinical implications of the results are discussed.

Allergens↗
PubMed1998

[Appearance of ovomucoid in coagulated egg yolk passing through from soluble fraction of coagulated egg white in boiled egg].

Ovomucoid is a egg white protein which has a strong allergenicity with a unique characteristic in heat-noncoagulable one contrast to heat-coagulable other major egg white proteins. By ELISA and immunoblots analysis, ovomucoid was detected in heat-coagulated egg yolk after immediate boiling of hen's egg for 15 min (boiled egg) at the concentration of 4.8 +/- 0.8 micrograms/g egg yolk, but not detected in raw egg yolk collected by insertion of a needle into the egg yolk cavity. Ovomucoid in heat-coagulated egg yolk was increased by standing the boiled eggs at room temperature for 10, 30, 60 and 120 min at the concentration of 7.5 +/- 3.4, 17.2 +/- 15.1, 28.1 +/- 5.9 and 78.8 +/- 31.3 micrograms/g egg yolk, respectively. The soluble fraction prepared from heat-coagulated egg white of boiled egg contained 37.7 +/- 3.2 mg/ml of proteins including 14.2 +/- 11.9 mg/ml of ovomucoid as a major and miners of detectable ovalbumin and ovotransfferin. These results suggested that the appearance of ovomucoid in coagulated egg yolk of boiled egg was due to passing the soluble fraction rich in ovomucoid in heat-coagulated egg white through into the coagulated egg yolk, which may have notable consequences for the present of ovomucoid as a major egg white allergen in yolk egg of boiled egg.

Allergens↗
PubMed1999

Inhibiting effects of egg white dry-heated at 120 degrees C on heat aggregation and coagulation of egg white and characteristics of dry-heated egg white.

Dialyzed and freeze-dried egg white (FDEW) was dry-heated at 120 degrees 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 degrees 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 aggregations and coagulations of ovotransferrin and lysozyme in the FDEW were inhibited by their bindings with the soluble aggregates in DHEW.

Animals↗