Yolk Samples Research Articles

UV-VIS-NIR spectroscopy and artificial neural networks for the cholesterol quantification in egg yolk

Artificial neural networks (ANN) are non-linear calibration methods that try to simulate the human nervous system with neurons, layers and transfer functions. In this study the input neurons were the UV-VIS-NIR spectra of egg yolks and the outputs were cholesterol content. Therefore, the aim of this work was to develop and assess a UV-VIS-NIR method coupled to chemometrics and ANN for cholesterol determination in egg yolks. A total of 57 samples of egg yolks were obtained from fresh shell eggs and pasteurised egg yolks. A total of 2311 variables (wavelengths) with four variable selection methods were analysed. An enzymatic method was used as reference method for cholesterol content. The effect of the solvent was also evaluated. The best results were obtained based on selected absorbance peaks. Calibration results showed r2cal over 0.90 and RMSEC below 0.65. Validation results showed r2val close to 0.7. The ANN model developed could be useful to determine cholesterol in egg yolk for routine quality control.

Influence of food commodities on hangover based on alcohol dehydrogenase and aldehyde dehydrogenase activities

Alcohol consumption often leads to hangover, a condition characterized by several symptoms, characteristically headache, nausea, fatigue and drowsiness. Hangover may be alleviated by altering the rate of alcohol metabolism and facilitating elimination of acetaldehyde by affecting the activity of alcohol dehydrogenase (ADH) and/or aldehyde dehydrogenase (ALDH) enzymes. In the present study, several food commodities like fruits, vegetables, cereals, pulses, dairy products, spices and other miscellaneous products (ascorbic acid, cocoa sample, tea, coffee, egg yolk and date samples) were investigated for their effect on the in vitro activities of the enzymes and their antioxidant properties. Of the many screened food commodities, few showed an increase in the activity of either one or both the enzymes, ADH and ALDH. Studies showed no correlation between ADH and ALDH enzyme activities and antioxidant property of the selected food commodities for anti-hangover effect. Further, an anti-hangover (AHO) product was developed using pear (65%), sweet lime (25%) and coconut water (10%) and, validated for in vitro ADH and ALDH enzyme activities. AHO product was found to enhance ADH and ALDH activities by 23.31% and 70.02%, respectively.

Characterization and discrimination of selected chicken eggs in China's retail market based on multi-element and lipidomics analysis.

The present study focuses on the differentiation of Deqingyuan (n = 90), Taihe (n = 90) and crossbred (n = 90) black-boned silky fowl eggs based on chemometrics analysis of multi-element and lipidomics data. A total of 53 chemical elements were simultaneously quantified in the eggs using inductively coupled plasma mass spectrometry. Multivariate statistical analysis of element data screened 30, 13 and 12 candidate discriminants for whole egg, egg yolk and egg white samples, respectively. Moreover, we utilized an LC-MS/MS-based lipidomics approach to profile lipids in the three types of egg yolks. In total, 1633 lipid species (including 43.78% glycerophospholipids, 25.66% glycerolipids, 16.66% fatty acyls, 6.86% sphingolipids, 4.10% sterol lipids, 1.53% polyketides, 1.10% prenol lipids and 0.31% saccharolipids) were consistently detected in all samples. A partial least squares discriminant analysis model was established based on the lipidomics data, which enables a 100% correct classification of the egg yolks. Using a cutoff of variable importance in projection value >1 and p value <.05, a panel of 22 potential lipid markers was discovered for the discrimination of Deqingyuan, Taihe and crossbred egg yolks. These results could facilitate a better understanding of the nutritional qualities of the evaluated eggs. Our method of combining chemical analysis with chemometrics offers a convenient and powerful tool to distinguish commercially-available eggs.

Cholesterol removal by Β-cyclodextrin modified cryogel column

In this presented work, synthesis of poly(HEMA-GMA) cryogel, its modification with β-cyclodextrin and its usability for cholesterol removal were investigated. For this, cryogels were prepared by cryocopolymerization technique and modified covalently by β-cyclodextrin. Prepared cryogels were characterized by FTIR, SEM studies and swelling test. Maximum cholesterol adsorption efficiency of the β-cyclodextrin immobilized poly(HEMA-GMA) cryogel was found to be as 291 mg/g cryogel. These β-cyclodextrin functionalized cryogels were used repeatedly for 50 times without any significant decrease in their cholesterol recognition capability. Cholesterol removal efficiency of the β-cyclodextrin immobilized poly(HEMA-GMA) cryogel was also tested from egg yolk, milk and artificial human serum samples.

The impact of maternally derived dioxins on embryonic development and hepatic AHR signaling in a long-lived apex predator

Dioxins and related contaminants are highly pervasive in aquatic systems and elicit deleterious effects in exposed organisms. Because dioxins exhibit a proclivity to bioaccumulate, long-lived predatory species are particularly vulnerable to their persistence in the environment. We have previously reported elevated expression of CYP1A2, a biomarker of dioxin exposure, in American alligator embryos collected from the Tom Yawkey Wildlife Center (YWC). This coastal population inhabits a system with historical dioxin contamination associated with industrial activities. Herein, we utilize ecological attributes of the alligator to address the persistence of dioxins and furans in yolk and their potential to drive changes in hepatic function. Specifically, we assess variation in expression of AHR signaling components in embryos and its connection to contaminant levels in matched yolk samples. Compared to a reference population, TEQ levels and total penta-, hexa-, octa-substituted CDDs were elevated at YWC. Contrary to predictions, TEQ levels were not significantly related to hepatic AHR1B or CYP1A2 expression. However, a significant association was detected between expression of both factors and embryo:yolk mass ratios, wherein decreasing embryo mass was negatively associated with CYP1A2 but positively associated with AHR1B. These findings suggest that variation in embryonic metabolism and developmental progression likely influence AHR signaling and dioxin toxicity in alligators and potentially other oviparous species. While dioxin concentrations observed in alligators in this study are lower than historical values reported for other wildlife species inhabiting this system, they indicate the continued presence and possible long-term influence of these contaminants in a high trophic status species.

Molecular Survey of Quinolone Resistance in Salmonella spp. Isolated From Poultry Products in Karaj, Iran

Background: Non-typhoidal salmonellae and serovars of Escherichia coli, Listeria, Shigella, and Campylobacter are among the most important food-borne bacterial agents. Objective: The aim of the present study was molecular detection of quinolone resistance in Salmonella spp. isolated from poultry products in Karaj, Iran, using polymerase chain reaction (PCR). Materials and Methods: Ninety samples of poultry products were collected from different brands and markets during September-December 2017. All samples were enriched in nutrient broth and Selenite F broth, and salmonellae were isolated by xylose lysine deoxycholate agar. The presence of specific genes of qnrA, qnrB, and qnrS was investigated employing PCR technique and subsequently, specific primers. Results: None of the 30 egg yolk samples had bacterial growth in the culture medium. In total, 29 (48.33%) out of 60 raw chicken meat samples were determined to be contaminated with Salmonella using culture-based methods (i.e., 7 (35%) out of 20 drumstick, 15 (62.5%) out of 24 breast, and 7 (43.75%) out of 16 liver samples). In addition, the frequency of qnrA, qnrB, and qnrS genes in the samples was 10.34%, 68.96%, and 86.20%, respectively. Conclusion: The results of this study showed a high frequency of Salmonella contamination and qnr genes in the contaminated samples.

A nanocomposite consisting of graphene oxide, zeolite imidazolate framework 8, and a molecularly imprinted polymer for (multiple) fiber solid phase microextraction of sterol and steroid hormones prior to their quantitation by HPLC.

A method is described for multiple monolithic fiber solid-phase microextraction of five sterol and steroid hormones from complex food samples. A composite was prepared from graphene oxide, a metal-organic framework (ZIF-8) and a molecularly imprinted polymers was deposited on a single thin fiber. Four thin fibers were combined to obtain a fiber bundle. The nanocomposite was characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy. The parameters affecting the extraction were optimized by Box-Behnken design. Following elution with methanol, the analytes progesterone, testosterone, β-sitosterol, cholesterol and campesterol were quantified via HPLC. Response is linear in the 0.01-1000μgL-1 concentration range, and limits of detection range from 3 to 5ngL-1. The method was successfully applied to the determination of the five analytes in spiked samples of white meat, egg yolks and vegetables. The relative mean recoveries ranged from 95.0% to 101.0%. Graphical abstract Schematic presentation of a monolith molecularly imprinting polymer (MIP) fiber fabrication for solid phase microextraction (SPME) of sterol and steroid hormones. The fiber was synthesis using graphene oxide and metal-organic framework, ZIF-8, composite by imprinting technique and progesterone as template. Four fibers were combined to obtain a fiber bundle. Then, multiple fiber solid-phase microextraction was employed for determination of analytes by coupling with HPLC/UV detection.

Analysis of antibody levels in egg yolk for detection of exposure to Ascaridia galli parasites in commercial laying hens

Ascaridia galli is one of the most abundant nematode parasites in poultry. A. galli infections can significantly impact the profitability of egg farms and have negative implications for bird health and welfare. The main objectives of this study were to determine whether A. galli specific antibodies in egg yolks can be used to detect prior or current exposure to A. galli in laying hens, and to distinguish between eggs obtained from caged and free-range hens. Twenty-two laying hen flocks from different production systems (10 free-range, 2 barn-housed, and 9 caged flocks) were enrolled in the study. An in-house enzyme-linked immunosorbent assay was used to analyze levels of A. galli specific antibodies in yolk. The numbers of A. galli eggs in hen excreta were also determined in a subset of farms. Free-range flocks had higher and also more variable levels of anti-A. galli antibodies in the egg yolk compared to those of the cage flocks (0.50 ± 0.39 vs. 0.16 ± 0.13 OD units) (P < 0.001). Results also confirmed that excreta from free-range and barn-housed flocks contained higher numbers of A. galli eggs than did excreta from caged flocks in which no A. galli eggs were detected. In conclusion, analysis of anti-A. galli antibodies in the egg yolk can be used to detect worm exposure in commercial layer flocks. However, the method used in this study cannot be used in isolation to distinguish between eggs from cage and free-range production systems as anti-A galli antibodies were detected in egg yolk samples from all production systems, and the range of antibody levels overlapped between production systems.

Antioxidant enzymes activity, GSH and MDA level in eggs from heritage breeds

The objective of the study was to determine the activity of antioxidant enzymes and the level of GSH and MDA in yolk and albumen of hen’s eggs. The experiment was carried out with 99 hens of three heritage breeds (‘Greenleg Partridge’ – group I, ‘Sussex’ – group II, ‘Rhode Island Red’ – group III). Layers were reared in the litter system and had outdoor access. Birds were fed ad libitum standard diets based on concentrates for laying hens and had free access to water throughout the experiment. All the groups were managed under uniform environmental (air humidity and temperature, lighting programme) and feeding conditions. At 48 weeks of age, 6 eggs from each group were collected. In the samples of egg yolks and albumens the concentration of GSH and MDA, and activity of SOD, GPx and CAT were estimated. The results were statistically analysed by one-way analysis of variance and significant differences were estimated with Duncan’s multiple range test. The highest activity of SOD, the highest level of GSH and the lowest level of MDA were characterised by eggs from ‘Sussex’ hens, which may indicate their best quality. Based on the obtained results, it can be concluded that the activity of antioxidant enzymes (mainly SOD) and the levels of GSH and MDA which occur in eggs may depend on the breed of hens.

Rare Earth Element Labeling as a Tool for Assuring the Origin of Eggs and Poultry Products

Laying hens were fed terbium and thulium supplemented feed in order to introduce a distinctive rare earth element pattern that allows discrimination of labeled from unlabeled poultry products. Samples of egg yolk, egg shells, meat, bones, liver, blood, and feces were analyzed using either conventional or laser ablation inductively coupled plasma mass spectrometry. Already after a short time of administering supplemented feed, terbium and thulium enrichment could be unambiguously detected in the products, while absolute terbium and thulium contents remained low enough to ensure safety for the customer. This method could potentially be applied to specifically label foodstuffs produced in certain regions or under certain conditions, in order to ensure food authenticity.

Protein-specific distribution patterns of perfluoroalkyl acids in egg yolk and albumen samples around a fluorochemical facility

In this study, eggs from free-range and barn chickens in farms around a fluorochemical facility were collected to assess the distribution profiles of perfluoroalkyl acids (PFAAs), including isomers of perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and perfluorohexane sulfonate (PFHxS), in egg yolk and albumen. The results revealed that the concentrations of PFAAs in yolks were significantly higher than those in albumen. All 17 PFAAs examined could be detected in yolks, showing decreasing concentrations with increasing distance from the fluorochemical facility. The three predominant compounds in yolks were perfluorobutanoic acid (PFBA, mean concentration 81.4 ng/g ww), PFOS (28.0 ng/g ww), and PFOA (4.83 ng/g ww), and this result is consistent with the product structure of the facility. Moreover, n-PFOA, n-PFOS, and n-PFHxS were the dominant contaminants in yolk, with mean concentrations of 4.75, 25.7, and 4.29 ng/g ww, respectively. In albumen, PFBA was still the predominant PFAA congener (mean concentration = 3.93 ng/g ww), followed by PFOA. Docking analysis indicated that the PFAAs presented higher binding abilities with the low density lipoprotein, high density lipoprotein, and vitellin proteins in yolk than that with ovalbumin albumen proteins, which might be the main factor influencing the possible difference in distributions of PFAAs in yolk and albumen.

Oxidative and physical stability, rheological properties and sensory characteristics of ‘salad dressing’ samples formulated with flaxseed oil and n-OSA starch

Flaxseed oil is one of the richest sources of Omega-3. This work was aimed at evaluating the physical qualities, sensory properties and the stability of a formulation for salad dressing characterized by a partial enrichment with flaxseed oil upon refrigerated storage. Samples were stabilized by n-OSA starch and sodium caseinate, and they were comparable with samples which had egg yolk only. All formulated dressings appeared as a weak gel-like structure with strong shear thinning behavior. The experimental data was fitted with the power-law model for all samples. The samples showed various degrees of oxidative stability after 90 days of storage. Salad dressings containing n-OSA starch and sodium caseinate (samples 1–4) exhibited a small phase separation at the bottom of the tubes in the third month of storage, while no oiling-off was observed. In the presence of egg yolk (sample 5), a higher stability was observed with no phase separation or oiling-off. When there was 5% (w/w) flaxseed oil, a higher sensory quality was obtained in general. Increasing the percentage of flaxseed oil replacement in salad dressings and prolonging the storage time led to a decrease in the L factor. Salad dressings could be enriched aptly with flaxseed oil emulsions (while being stabilized by n-OSA starch and caseinate).

Direct cholesterol and β-sitosterol analysis in food samples using monolithic molecularly-imprinted solid-phase microextraction fibers coupled with high performance liquid chromatography

A novel monolithic molecularly imprinted polymer fiber-solid phase microextraction method was developed for the simultaneous determination of cholesterol and β-sitosterol in cow milk, egg yolk and olive oil samples by high-performance liquid chromatography. A flexible MIP monolithic fibers with high chemical and thermal stabilities were simply synthesized using a narrow bore silica capillary as a mold by the copolymerization of methacrylic acid and ethylene glycol dimethacrylate imprinted with β-sitosterol. The prepared MIPs were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM). The main factors that affect the extraction efficiency, such as extraction time, desorption time, desorption solvent, and stirring rate were investigated and optimized. Under the optimized extraction conditions, the limits of detection of the proposed method were 0.03 µg L−1 and 0.05 µg L−1, for cholesterol and β-sitosterol, respectively. Satisfactory linearity was achieved in the range of 0.1–20 µg L−1 for analytes with the correlation coefficients (r) above 0.9975 and RSD less than 3.5%. This procedure was successfully applied for the determination of cholesterol and β-sitosterol in different food samples.

Development and Validation of Predictive Model for Salmonella Growth in Unpasteurized Liquid Eggs.

Liquid egg products can be contaminated with Salmonella spp. during processing. A predictive model for the growth of Salmonella spp. in unpasteurized liquid eggs was developed and validated. Liquid whole egg, liquid yolk, and liquid egg white samples were prepared and inoculated with Salmonella mixture (approximately 3 Log CFU/mL) containing five serovars (S. Bareilly, S. Richmond, S. Typhimurium monophasic, S. Enteritidis, and S. Gallinarum). Salmonella growth data at isothermal temperatures (5, 10, 15, 20, 25, 30, 35, and 40°C) was collected by 960 h. The population of Salmonella in liquid whole egg and egg yolk increased at above 10°C, while Salmonella in egg white did not proliferate at all temperature. These results demonstrate that there is a difference in the growth of Salmonella depending on the types of liquid eggs (egg yolk, egg white, liquid whole egg) and storage temperature. To fit the growth data of Salmonella in liquid whole egg and egg yolk, Baranyi model was used as the primary model and the maximum growth rate and lag phase duration for each temperature were determined. A secondary model was developed with maximum growth rate as a function of temperature. The model performance measures, bias factor (Bf, 0.96-0.99) and r2 (0.96-0.99) indicated good fit for both primary and secondary models. In conclusion, it is thought that the growth model can be used usefully to predict Salmonella spp. growth in various types of unpasteurized liquid eggs when those are exposed to various temperature and time conditions during the processing.

A new method for measuring thyroid hormones using nano-LC-MS/MS

This paper describes a novel mass spectrometry based analytical method for analyzing thyroid hormones (THs). Thyroid hormones play a critical role in the regulation of many biological processes such as growth, metabolism and development. Several analytical methods using liquid chromatography-mass spectrometry (LC–MS) and tandem mass spectrometry (LC–MS/MS) have previously been developed to measure THs, especially in humans. For biomedical and toxicological research using small animal models, and in ecophysiological research using wild species where sample volume is limiting, sensitive methods are needed. In this study, we developed a nano-LC-MS/MS method enabling quantification of low concentrations of two key THs, thyroxine (T4) and 3,3′,5-triiodothyronine (T3). The method was tested with egg yolk samples. We used a low flow rate (300 nl/min) to obtain maximal sensitivity of the method. The limit of quantitation was 10.6 amol for T4 and 17.9 amol for T3. The method shows good linearity (r > 0.99), repeatability and reproducibility (CVs <10%). We also reanalyzed yolk samples with radioimmunoassay for a comparison of the newly developed and previously used methods. Finally, we applied the methodology to measure hormones in egg yolk extracts in multiple avian species, and report interesting variation in maternal TH deposition. The newly developed nano-LC-MS/MS method is thus suitable for measuring THs in low concentrations and across species.

Effects of adding egg yolks of different avian species to Tris glycerol extender on the post-thawing quality of buck semen

The effects of adding egg yolks (EY) of different avian species to the Tris glycerol extender was evaluated for post-thawing quality of buck semen. The semen samples collected from seven Aardi bucks were pooled and diluted 1:4 with the Tris glycerol diluents containing the egg yolks of chicken (C), pigeon (P), goose (G), Japanese quail (Q), duck (D), or turkey (T). The diluted semen samples were gradually cooled to 5 °C within 2 h, equilibrated at 5 °C for 2 h, and then frozen in liquid nitrogen vapor for 8 min before storing them at −196 °C. The frozen straws were thawed at 37 °C for 30 s and evaluated for sperm motility, vitality, abnormality, plasma-membrane integrity, and DNA fragmentation. The malondialdehyde (MDA) and reduced glutathione (GSH) activities were measured. The egg yolk samples of the above-mentioned avian species (n = 7/species) were analyzed for moisture, ash, protein, fatty acid (FA), and trace element contents. The use of the chicken EY (C) diluent resulted in better post-thawing buck semen quality, including the total progressive sperm motility parameters, sperm vitality, plasma membrane intactness, DNA integrity, and sperm abnormalities percentages, in comparison with the EY diluents of the other avian species. The lowest MDA and the highest GSH activities were observed in the C diluent. The chicken EY had the highest percentages of margaric and linolenic FAs and the lowest percentages of palmitoleic and myristic FAs. Moreover, the percentage of oleic FA was lower in the chicken EY than in the EYs of other species, except turkey. Additionally, the chicken EY had the significantly lowest concentration of Cu, Zn, Fe, and Mn. In conclusion, the use of chicken egg yolk extender is recommended for buck semen cryopreservation. The egg yolks of the other avian species studied cannot substitute the chicken EY as they gave poorer post-thawing semen quality. The EY composition, especially FA profile and trace elements concentration, significantly affected the post-thawing quality of buck semen.

Multiplication in Egg Yolk and Survival in Egg Albumen of Genetically and Phenotypically Characterized Salmonella Enteritidis Strains

Prompt refrigeration of eggs to prevent the multiplication of Salmonella Enteritidis to high levels during storage is an important practice for reducing the risk of egg-transmitted human illness. The efficacy of egg refrigeration for achieving this goal depends on the interaction among the location of contamination, the ability of contaminant strains to survive or multiply, and the rate at which growth-restricting temperatures are attained. The present study assessed the significance of several characterized genetic and phenotypic properties for the capabilities of 10 Salmonella Enteritidis isolates to multiply rapidly in egg yolk and survive for several days in egg albumen during unrefrigerated (25°C) storage. The growth of small numbers of each Salmonella Enteritidis strain (approximately 101 CFU/mL) inoculated into egg yolk samples was determined after 6 and 24 h of incubation. The survival of larger numbers of Salmonella Enteritidis (approximately 105 CFU/mL) inoculated into albumen samples was determined at 24 and 96 h of incubation. In yolk, the inoculated Salmonella Enteritidis strains multiplied to mean levels of approximately 102.6 CFU/mL after 6 h of incubation and 108.3 CFU/mL after 24 h. In albumen, mean levels of approximately 104.6 CFU/mL Salmonella Enteritidis were maintained through 96 h. The concentrations of the various Salmonella strains after incubation in either yolk or albumen were distributed over relatively narrow ranges of values. Significant ( P < 0.01) differences observed among individual strains suggested that maintenance of the fimbrial gene sefD may have positive genetic selection value by improving fitness to grow inside egg yolk, whereas the antibiotic resistance gene blaTEM-1 tet(A) appeared to have negative genetic selection value by decreasing fitness to survive in egg albumen.

Detection of Ascaridia galli infection in free-range laying hens

Reliable methods for detection of A. galli infection using excreta egg count (EEC) and ELISA assays to determine A. galli specific IgY levels in serum and yolk samples were compared from hens infected naturally and artificially. Artificially infected hens were used to generate samples for analysis of preferred detection methods and to generate contaminated ranges for use in the naturally acquired infection study in which Lohmann Brown hens (n = 200) at 16 weeks of age were randomly assigned to four treatments with five replicate pens. Hens of negative control (NC) ranged on a decontaminated area, hens of low infection, medium infection and positive control (PC) ranged on the areas previously contaminated by hens artificially infected with 250, 1000 and 2500 A. galli eggs/hen, respectively. Additionally, hens of PC were orally infected with 1000 A. galli eggs/hen. Anti A. galli antibody levels in hen serum (SIgY) and yolk (YIgY) were measured before range access, and 2, 7 and 12 weeks after access to the contaminated ranges. In a natural infection study, eggs were detected in the excreta of all hens 4 weeks after range access, with the exception of NC in which no eggs were detected. EEC increased to reach maximum value (2204 ± 307 eggs/g) after 11 weeks of range access and then declined at 12 weeks (905 ± 307eggs/g) (p < 0.01). While SIgY OD values were not different in hens between any groups before range access, after 2 weeks, both SIgY and YIgY gradually increased in hens of PC (1.17 ± 0.03 and 0.88 ± 0.04) and medium infection (1.07 ± 0.03 and 0.96 ± 0.04) compared to low infection (0.38 ± 0.03 and 0.29 ± 0.04) (p < 0.01) and NC. After 12 weeks, SIgY were similar in hens of PC, medium and low groups whereas YIgY was higher in hens of low infection group (p < 0.01). Sensitivity of the serum and egg yolk antibody levels assay to detect A. galli infection was 100% and 96%, respectively, whereas the pooled EEC method yielded a sensitivity of 93%. The results of this study suggest that hens naturally infected with A. galli produce both SIgY and YIgY at different levels depending on the infection intensity and duration of exposure which allows the diagnosis of prior infection or early diagnosis of current infection. Use of the practical and non-invasive method of yolk sample analysis for detecting IgY can be just as informative as using serum samples to detect A. galli infection.

Characterization of chicken IgY produced against H5 and H9 avian influenza viruses

Avian influenza viruses are causing sever drawbacks on the poultry industry in Egypt requiring additional approaches together with vaccination to overcome its endemicity. On this study, twelve white Hy-Line layers were immunized with H5N1 and H9N2 viruses. Throughout the experiment (8 weeks), regular blood samples were collected weekly with daily egg collection. The purified IgY was tested for titres and specificity in hens' sera and egg yolk samples using Hemagglutination-inhibition(HI) and neutralization tests(NT). HI test showed that the antibodies titre values against H5N1 and H9N2 increased from the 1st week in the serum and 2nd week in the yolk until reaching a peak at the 4th week in serum and 5th week in the yolk. The peak was maintained over 3 weeks in the yolk of H5N1 and H9N2 and in the serum of H5N1 and over 4 weeks in the serum of H9N2 followed by non-significant decrease until the 8th week. The percentage of transfer of H5N1 antibodies ranged from 6.25% to 50% and for H9N2 ranged from 3.12% to 12.5%. NT showed that the neutralization index of H5N1 and H9N2 were toward homologous 3.9 and 5.04, respectively. Cross NT showed no egg protection with 100% death, but with retardation of the death time. In Conclusion, our results revealed the presence of significant titres of purified IgY against H5N1 and H9N2 influenza viruses in eggs and the possible role of egg yolk IgY in neutralization of avian influenza viruses.

Analysis of color changes in chicken egg yolks and whites based on degree of thermal protein denaturation during ohmic heating and water bath treatment

Raw eggs were separated into yolks and whites before thermal treatment. An ohmic heating process at 20 kHz and 30 V was used for egg-yolk samples, and color changes were monitored with a computer vision system. Egg-white samples were treated with a water bath, and absorbance, as an expression of turbidity, was determined spectrophotometrically. Thermal protein denaturation of egg samples was analyzed by differential scanning calorimetry (DSC) using the dynamic method, and estimated for several thermal schedules by kinetics analysis. The DSC thermogram was characterized by two endothermic peaks in each sample. With increasing temperature, the yolk gradually turned from a plain orange to a vivid yellow color, while the white gradually changed from transparent to cloudy. For all samples, an accurate correlation was obtained between color changes and the non-denaturation ratio of the second peak temperature. Results are of potential value for the modeling and design of egg-based products.