Storage Of Shell Eggs Research Articles

Effect of ultrasound and alkali-heat treatment on the thermal gel properties and catechin encapsulation capacity of ovalbumin

Ovalbumin (OVA) is widely used to prepare nanocomposites for the delivery of bioactive compounds. During long-term storage of shell eggs, natural OVA is slowly transformed into a more heat-stable form called S-OVA, which can also be obtained artificially through alkali-heat treatment. This study aimed to reveal the effects of alkali-heat and ultrasonic treatment on the structure, stability and polyphenol encapsulation ability of OVA by analyzing the interaction mechanism through molecular docking and multispectral analysis. The results showed that the proteins treated with alkali-heat and ultrasound had higher stability and surface hydrophobicity, reflecting the change in their functional properties. The S-OVA generated by alkali-heat treatment had higher thermal stability and formed softer gels than those generated by ultrasound treatment. The results of infrared spectroscopy and molecular docking indicated that hydrophobic interactions and hydrogen bonds were the main forces stabilizing the formation of catechin-OVA complexes. X-ray diffraction showed that OVA was a good carrier for catechins, which existed in an amorphous state in the hydrophobic core of proteins. Both ultrasound and alkali-heat treatments exposed hydrophobic groups in the protein and significantly enhanced the ability of the protein to bind polyphenols (increased from 15.72 nmol/mg to 44.10 nmol/mg and 43.18 nmol/mg, respectively), resulting in greater antioxidant capacity. This study mainly revealed the binding mode of OVA with polyphenols and explained the reasons for the changes in the functional properties of OVA by revealing the structural changes in proteins under different treatments, providing a basis for the advantages of alkali-heat and ultrasonic treatment of OVA in the food industry.

Transition of serine residues to the d-form during the conversion of ovalbumin into heat stable S-ovalbumin

Ovalbumin, a major protein in chicken egg white, is converted into a more thermostable molecular form, known as S-ovalbumin, during the storage of shell eggs. Our previous X-ray crystallographic study indicated that S-ovalbumin contains three d-Ser residues (S164, S236, and S320), which may account for its thermostability. Here, we confirmed the presence of these d-Ser residues in ovalbumin using a technique combining deuterium labeling of α-protons of amino acids and liquid chromatography-tandem mass spectrometry (LC–MS/MS). Ovalbumin from chicken egg white and recombinant ovalbumin were incubated for approximately 12 days at pH 9.5 and 37°C. They were then hydrolyzed in DCl/D2O vapor, derivatized with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F), and analyzed by LC–MS/MS. A time-dependent increase in the d-Ser contents in native ovalbumin was observed over a period of 7 days, reaching approximately 8%. This corresponds to a value of three serine residues per molecule, and is consistent with the prediction based on our previous crystallographic analysis. Nearly identical results were obtained with recombinant ovalbumin. We then used this technique to investigate whether d-amino acid residues could arise within other proteins under mild alkaline conditions and detected small but significant amounts of d-Ala and/or d-Ser residues that increased in a time-dependent manner in some proteins.

Storage induced conversion of ovalbumin into S-ovalbumin in eggs impacts the properties of pound cake and its batter

Storage of shell eggs for 28 days at 6 or 23 °C converts ovalbumin (which represents over 50% of egg white protein) into its more thermostable intermediate and S-ovalbumin forms. Their increased thermostability causes them to expose their sulfhydryl groups only at higher temperatures than does ovalbumin itself. During pound cake baking, the loss in protein extractability under non-reducing conditions (further taken as a measure of protein network formation) occurred later when egg white from stored eggs rather than from fresh eggs was used. The incorporation of the more thermostable forms of ovalbumin (i.e. intermediate and S-ovalbumin) in the protein network occurred later than did that of ovalbumin. The moment at which ovalbumin denatures determines when the largest decrease in overall protein extractability occurs, which points to ovalbumin having a key role in protein network formation during cake baking. However, at the end of the process, the overall baking induced loss of protein extractability was similar when egg white from either fresh or from stored eggs was used. Rapid Visco Analyser measurements showed that this delay in protein network formation impacts cake batter viscosity. While cakes baked with fresh or stored egg white were of similar volume, cake crumb cohesiveness and springiness of cakes produced with fresh egg white were higher than those of cakes produced with stored egg white.

Effect of various refrigeration temperatures on quality of shell eggs

The objective of this study was to evaluate the effects of low storage temperatures on shell egg quality. Approximately 2100 shell eggs were collected and stored at - 1.1, 0.6, 2.2, 3.9, 5.6 and 7.2 °C for up to 4 weeks. Eighteen eggs at each storage temperature were evaluated after 0, 2, 7, 14, 21 and 28 days of storage. Haugh units (HU), yolk index (YI), albumen pH (pHA), yolk pH (pHY) and angel food cake density (CD) were measured. Shell egg quality tended to be preserved better at below 2.2 °C, as high HU and YI values relative to eggs stored at 7.2 °C were determined on day 28. However, storage at - 1.1 °C tended to cause the opposite effect, especially highly declined HU values over time. Significantly different HU values of shell eggs were measured after 14 days of storage, with eggs stored at 0.6 and 2.2 °C having the highest HU values, 80.42 and 77.97 respectively. A lower temperature limit for shell egg storage could be established between 0.6 and 2.2 °C, as both temperatures showed the highest HU values, 77.88 and 77.60 respectively, after 28 days of storage.

Effect of Shell Eggs Storage on Ovomucin Extraction

Ovomucin, one of the major egg white proteins, has wide potential applications in food, functional food and nutraceutical industries due to its unique physicochemical properties and bioactivities. A new two-step method was recently developed to prepare high purity ovomucin; in this study, effect of shell egg storage on ovomucin extraction was investigated. The composition of ovomucin extracts from egg white was determined by gel filtration chromatography. Both storage temperature and time could significantly (p < 0.05) affect the purity and yield of the ovomucin. After 9 weeks of storage at 4 °C, the content of the ovomucin in the extract decreased from 92.5% to 82.4%, and the yield of ovomucin decreased from 214 to 120 mg/100 g of egg albumen (egg white). After 5 weeks of storage at 22 °C, the content of ovomucin extract decreased from 92.5% to 73.0%, and the yield of ovomucin decreased from 214 to 112 mg/100 g of egg albumen. Increase in egg white pH during prolonged storage leading to degradation of ovomucin is very likely responsible for the decreased extractability of ovomucin.

Protein‐Engineering Study of Contribution of Conceivable D‐Serine Residues to the Thermostabilization of Ovalbumin under Alkaline Conditions

During storage of shell eggs, an egg-white protein, ovalbumin is converted into a molecular species with higher thermostability (Delta T(m)=8 degrees), which is named as S-ovalbumin. Since the pH of egg white is raised to 9.5 in that process, particular chemical modifications could occur. Although any evidence for relationship between chemical modifications and the thermostabilization had not been established, our X-ray crystallographic model for S-ovalbumin demonstrated that three serine residues (S164, S236, and S320) might be in D-configuration. Then, whether these serine residues contribute to the thermostabilization in S-ovalbumin is investigated by protein-engineering approach. By alkaline treatment, S236G mutant was converted to a more thermostable form, as well as ovalbumin has been converted to S-ovalbumin. Hence, the Ser236 is regarded to have no contribution to S-ovalbumin formation. On the contrary, S164G and S320G did show accelerated conversion to thermostable forms in comparison with ovalbumin or wild-type recombinant protein. When these residues were replaced with valine, which has a slower racemization rate, Delta T(m) after alkaline treatment had become half of that for the wild-type recombinant ovalbumin. Therefore, the process of S-ovalbumin formation is deduced to consist of two steps, which is closely related to the two serine residues.

Combination of Super Chilling and High Carbon Dioxide Concentration Techniques Most Effectively to Preserve Freshness of Shell Eggs during Long‐Term Storage

This study was made to examine the combined effects of stored temperature and carbon dioxide atmosphere on shell egg quality. The shell eggs were packed into polyethylene terephthalate/polyethylene (PET/PE) pouches and stored at 0 degrees C (super chilling), 10 degrees C, and 20 degrees C, respectively for 90 d. The atmospheric carbon dioxide concentration was controlled to obtain the 3 concentration levels of high (about 2.0%), medium (about 0.5%), and low (below 0.01%). Changes in Haugh unit (HU) values, weakening of vitelline membranes, and generation of volatiles were analyzed to evaluate the freshness of shell eggs. Results showed that, compared with the other combinations, the technique of super chilling and high carbon dioxide concentration enabled shell eggs to be most effectively stored for 90 d, based on estimations of the statistical significances of differences in HU values, and on maintaining the initial HU values during storage. In addition, the storage of shell eggs using this combination technique was found to significantly prevent the weakening of the vitelline membrane based on the estimations of numbers of eggs without vitelline membrane breakage when eggs broke, and significantly lowered the incidence of hexanal in the yolk from exposure to the gas chromatographic-mass spectrometric analyses of volatiles. Thus, these results confirmed that the combination of super chilling and high carbon dioxide concentration was the most effective technique for preserving shell eggs during a long term of 90 d compared with other combination techniques.

Effect of Natural Antioxidant on Oxidative Stability of Eggs and Productive and Reproductive Performance of Laying Hens

The main target of this study was to determine the effect of dietary natural antioxidants: Thyme, rosemary, oregano and curcuma longa on production and reproduction performance of laying local hens and study the oxidative stability of yolk shell egg storage at room temperature (16 C±2). A total number of 360 o hens and 36 cocks from El-Salaam strain of 28 weeks old were divided into 12 groups with 3 replicate each (10 hens +1 cock). Birds were fed on the experimental diets, using two levels (0.5 and 1.0%) from four types of herbs (oregano, thyme, rosemary, curcuma longa) as natural antioxidants, in comparison to two levels of vitamin E (100 and 200) mg/Kg diet, in addition to two diets, one using vitamins and minerals premix with vitamin E (control) and the other without vitamin E (Negative-control).The main results obtained from this study can be summarized as follows: Addition of herbs as natural antioxidants during the laying period can improve the production performance especially at 1.0% thyme, rosemary, oregano or 0.5% curcuma longa increased egg production, egg mass and improved feed conversion. Addition of 1.0% curcuma longa increased numerically values of shell weight and egg shape index. This treatment increased percentage of yolk weight and improved yolk colour by 10.87% and 15.62%, respectively compared to control group. Addition 1.0% oregano gave the highest values of all nutrient digestibility coefficients; except ether extract digestibility that was the lowest value compared to control diet, however it was statistically insignificant. Statistically, the highest values (P<0.05) of antibody titter against sheep red blood cells were recorded for hens fed 1.0% thyme or rosemary. Thyme or rosemary at 1.0% significantly decreased plasma total lipid, in comparison to the control by 17.15 and 27.15%, respectively while total cholesterol and LDL- cholesterol decreased insignificantly. Addition of thyme, rosemary or curcuma longa at 1.0% significantly decreased yolk total lipid, in comparison to the control group by 12.14, 13.19 and 13.95%, respectively. Addition of 1 % oregano or rosemary or 0.5 and 1.0% curcuma longa during laying period significantly decreased malonaldehyede formation in egg yolk and had positive effect on oxidative stability of shell eggs storage at room temperature(16oC±2). Addition of 1.0% oregano, rosemary or 0.5% curcuma longa significantly increased the percentages of fertility. While 1.0% thyme or 0.5-1.0% curcuma longa significantly increased the percentages of hatchability of fresh eggs. It could be concluded from this study that herbs could be used as natural antioxidants during laying period. Oregano, rosemary or thyme at 1.0% or curcuma longa at 0.5% can improve productive performance, fertility and hatchability and had positive effect on oxidative stability of shell eggs during storage.

In vitro Survival and Growth of Salmonella Typhimurium inoculated on Yolk Membrane after long Term refrigerated Storage of Shell Eggs

Salmonella enterica serovar Typhimurium has been isolated from commercial egg production facilities in the United States. Given its importance as a causative organism for food-borne salmonellosis, identifying approximate timelines for bacterial invasion of the egg is needed. The objective of this study was to examine net growth of S. Typhimurium in egg components over time. In trial 1 eggs were collected over a 24 hour period from a flock of single comb white leghorn hens while in trial 2 eggs were picked up from a commercial laying source once a week over the course of eight weeks and stored. Eggs were held at refrigeration temperature and each week, subsets of eggs were cracked, separated into yolk and albumen components, and inoculated with 108 CFU/ml of novobiocin and nalidixic acid (NO/NA) resistant S. Typhimurium onto the vitelline membrane of the egg. Yolks were then covered with albumen. Eggs were incubated for twenty-four hours at 25°C. After incubation eggs were again separated into albumen, yolk, and vitelline membrane samples. In trial 1, S. Typhimurium net growth occurred in albumen by the second week and continued from 4 to 8 weeks while in trial 2 net growth only occurred at week 5 and 7. S. Typhimurium net growth on vitelline membranes occurred by 2 weeks and continued from 4 to 8 weeks in trial 1 while no net growth occurred in trial 2 over the 8 week period. Yolk samples showed no net increases in S. Typhimurium populations over the 8 week period.

In vitro Survival and Growth of Salmonella Typhimurium inoculated on Yolk Membrane after long Term refrigerated Storage of Shell Eggs

In vitro Survival and Growth of Salmonella Typhimurium inoculated on Yolk Membrane after long Term refrigerated Storage of Shell Eggs

Thermostability of Refolded Ovalbumin andS-Ovalbumin

Ovalbumin, a member of the serpin superfamily, is transformed into a thermostabilized form, S-ovalbumin, during storage of shell eggs or by an alkaline treatment of the isolated protein (DeltaT(m)=8 degrees C). As structural characteristics of S-ovalbumin, three serine residues (Ser164, Ser236 and Ser320) take the D-amino acid residue configuration, while the conformational change from non-thermostabilized native ovalbumin is very small. To assess the role of the structural characteristics on protein thermostabilization, ovalbumin and S-ovalbumin were denatured to eliminate the conformational modulation effects and then refolded. The denatured ovalbumin and S-ovalbumin were correctly refolded into the original non-denatured forms with the corresponding differential thermostability. There was essentially no difference in the disulfide structures of the native and refolded forms of ovalbumin and S-ovalbumin. These data are consistent with the view that the configuration inversion, which is the only chemical modification directly detected in S-ovalbumin so far, plays a central role in ovalbumin thermostabilization. The rate of refolding of S-ovalbumin was greater than that of ovalbumin, indicating the participation, at least in part, of an increased folding rate for thermodynamic stabilization.

Effect of Dietary Thyme on the Oxidative Stability of Egg Yolk

The effect of dietary thyme on the oxidative stability of shell eggs over a 60-day refrigerated storage has been evaluated. Also, the influence of dietary thyme and storage time on the oxidative stability of liquid yolks adjusted to various pH values and agitated in the absence or presence of light has been investigated. Yolk lipid oxidation was determined by monitoring malonaldehyde formation through use of third-order derivative spectrophotometry. Results showed that although malonaldehyde is not produced during storage of shell eggs, it is present in the yolk of fresh eggs. It is also evident that thyme treatment reduced oxidation of liquid yolk, which significantly increased with light and increased acidity at pH 3 and declined thereafter as acidity increased to pH 2. A comparative examination of the antioxidant activity of various synthetic and natural antioxidants added to yolk suggested that thymol, the main antioxidant constituent of thyme, cannot be considered totally responsible for the oxidative resistance of the thyme-treated yolk. There may be additional thyme components with antioxidant activity that pass into egg yolk providing antioxidant properties. Keywords: Dietary thyme; yolk stability; lipid oxidation; egg storage; malonaldehyde

Evolution of Chemical and Physical Yolk Characteristics during the Storage of Shell Eggs

Yolk modifications during the storage of eggs could influence the quality of yolk products. The aim of this research was to study the rheological behavior and the evolution of some chemical paramet...

Evolution of Chemical and Physical Albumen Characteristics during the Storage of Shell Eggs

The aim of this paper was to study the evolution of furosine, pyroglutamic acid, and uridine and rheological characteristics of albumen from shell eggs stored over long times at 30, 20, and 5 °C. The chemical variables showed an increase in function of the storage temperature with more evident variations at room temperatures. At 5 °C, furosine increase was very low, while uridine presented a rapid increase after 150 days; pyroglutamic acid, instead, showed an even increase throughout the storage. The main decrease of viscosity happened during the first storage period; viscosity remained almost constant after 4, 6, and 36 days at 30, 20, and 5 °C, respectively. During the storage of eggs, a transition from pseudoplasticity to Newtonity was observed, while the aggregation temperature, evaluated through viscosity measurements, remained constant at 61−62 °C. Furosine, pyroglutamic acid, and uridine were generally well-correlated (P > 99%) between them, while the correlation with viscosity was lower. Keywords: Albumen; egg freshness; furosine; pyroglutamic acid; rheological behavior; uridine

Volatile Compounds in Scrambled Eggs

ABSTRACTVolatile compounds in scrambled eggs were analyzed by dynamic headspace sampling, high resolution gas chromatography and mass spectrometry. Thirty‐eight compounds were identified including aldehydes, ketones, alcohols, furans, esters, benzene derivatives, alkancs, sulfur‐containing compounds and a terpene. Selected compounds were quantified. Aldehydes were the most abundant volatile compounds in the egg samples. Volatile styrene monomer increased in scrambled egg samples during 2 wk storage of shell eggs in polystyrene containers. Scrambled eggs prepared from supermarket shell eggs contained 7 times more ethylbenzene and styrene than those prepared from fresh farm eggs stored in polystyrene containers for 2 wk.

Effect of Storage of Shell Eggs on Heat-induced Aggregation of Yolk and Whole Egg

Effect of Storage of Shell Eggs on Heat-induced Aggregation of Yolk and Whole Egg

The relationship between interior yolk position and Hangh unit on storage of shell eggs

The relationship between interior yolk position and Hangh unit on storage of shell eggs

Effect of Oiling Variables on Storage of Shell Eggs at Elevated Temperatures

Four experiments were conducted to determine 1) the effect of egg temperature (12, 22, and 32 C), oil temperature (12, 22 and 32 C), and storage temperature (12, 22 and 32 C) at time of oiling on egg quality; 2) effect of egg shell temperature (32, 52, and 72 C for 5 min) resulting from washing prior to oiling on egg quality; 3) length of time oiling can be delayed (3, 9, 27, or 81 hours) with eggs held at 32 C prior to oiling and still maintain grade A eggs at 12, 22, and 32 C storage; 4) effect of exposure of eggs to a CO2 atmosphere under pressure prior to oiling on egg quality. The last experiment used CO2 pressures of .7, 1.1, 1.4, and 1.8 kg/cm2 for 5, 15, 30, and 60 sec in study 1 and for .5, 1, 2, 4, and 8 min in study 2.The first experiment indicated that the temperature at which eggs were held prior to oiling was the main factor in determining the length of time eggs could be stored and remain grade A. Oil temperature and egg temperature at the time of oiling, had little effect on interior quality after 4 weeks. As expected, storage temperature was the major factor affecting grade.Preheating eggs to simulate washing prior to oiling had no effect on interior quality. The eggs remained grade A during the 4-week storage period at all storage temperatures.The length of time eggs were held at 32 C prior to oiling and subsequent storage temperature were both found to affect interior quality. Immediate oiling after lay maintains the best interior quality but is not necessary to maintain grade A eggs for 4 weeks even under extremes of holding and storage temperatures. Eggs stored at 12 C did not drop below grade A even when eggs were held 81 hr at 32 C prior to oiling. Eggs stored at 22 C declined to grade B when held 27 hr at 32 C, and those held at 32 C dropped to grade B after holding for 9 hr at 32 C prior to oiling.Exposure of eggs to a pressurized CO2 atmosphere for varying lengths of time at several pressures and oiling under these conditions had little effect on interior quality of the egg.

The Influence of Storage of Shell Eggs Produced by Hens Fed Crude Cottonseed Oil on the Lipovitellins Isolated from These Eggs

Approximately half of the lipovitellin of stored shell eggs laid by hens fed a diet containing crude cottonseed oil was in a granule fraction which was not soluble in 0.7 M sodium acetate solution. The lipovitellins of this granule fraction were not isolated in the preparation of lipovitellin. The lipovitellins isolated from stored eggs contained slightly more β-lipovitellin than those isolated from fresh eggs. During storage of the eggs, some of the α-lipovitellin was converted to a lipoprotein which was eluted differently from an hydroxylapatite column than either α- or β-lipovitellin.

The Influence of Storage of Shell Eggs Produced by Hens Fed Crude Cottonseed Oil on the Very Low Density Lipoproteins Isolated From These Eggs

Very low density lipoproteins were isolated from fresh and from 6-month old eggs laid by hens fed a diet containing crude cottonseed oil. There were no differences between the very low density lipoproteins isolated from the fresh and those from the stored eggs in the percentage of lipid extracted by ether after the action of unfolding agents, detergents, reducing agents, trypsin, Pronase, or phospholipase D. Phospholipase C released less lipid from the very low density lipoproteins of the stored eggs than from those of the fresh unless they were extracted with ether before digestion, when equal amounts were extracted. Very low density lipoproteins isolated from fresh eggs and those isolated from stored eggs contained similar percentages of lipid. The very low density lipoproteins from the stored eggs had lower isoelectric points than those from fresh eggs, but there were no differences in average size when determined by electron microscopy. Egg yolk very low density lipoproteins are normally quite stable in water solution, but those from the stored eggs showed evidence of some decomposition during prolonged ultracentrifugation in water solution in contrast to those from fresh eggs.