Simple Separation of Immunoglobulin from Egg Yolk by Ultrafiltration

A water-soluble fraction (WSF) was prepared by filtering 10 times diluted yolk (pH 5.0) stored at 4–6°C through Whatman No. 52 or No.1 filter paper for delipidation. However, solid-phase delipidation using an octadecyl column after filtration through a cellulose powder column was more practical for industrial application. After ultrafiltration (UF) of the WSF (pH 9.0,1.5M NaCl), results showed: Amicon 80–85% recovery, 74–99% purity; Harp 72–74% recovery, 81–84% purity; A/G 75% recovery, 89% purity; Koch 88% purity.     

Clarification of Spray-Dried Egg Yolk Suspensions and Solubilization of Proteins from Lipoproteins

The separation of proteins and lipids from spray-dried egg yolk was attempted using commerical enzymes and mold enzymes. Good solubilization of protein from a spray-dried egg yolk suspension (clarification of the suspension), could not be obtained with purified commercial enzymes (protease, lipase and phospholipase), but three crude enzymes extracted from molds and one commercial enzyme produced good results. Among them, Newlase F (crude preparation, derived from the genus Rhizopus) successfully clarified the spray-dried egg yolk suspension (pH 4.7, 40°C, 5–8 hr), thereby solubilizing about 85% of the total protein in the whole spray-dried egg yolk.     

Immunoglobulin Separation from Egg Yolk: A Serial Filtration System

A serial filtration system was developed for separating immunoglobulin from egg yolk (IgY). Egg yolk was diluted 10 times with water, adjusted to pH 5.0, frozen, then thawed. The diluted yolk was diafiltered through a hard filter paper at 4-6°C to produce a clear water-soluble fraction (WSF). The WSF was then delipidated by filtering through a hydrophobic membrane filter. Ultrafiltration of delipidated WSF at pH 9.0, at 4-6°C, in the presence of 1.5M NaCl resulted in electrophoretically pure (>90%) IgY with a recovery of about 92%. Advantages of this method are the use of only a few mild chemicals and the potential of developing a continuous process.     

Fractionation of Water-Soluble and -Insoluble Components from Egg Yolk with Minimum Use of Organic Solvents

A process was developed to fractionate both water-soluble and water-insoluble components from egg yolk with maximum retention of biological and functional properties. About 60–90% of the immunological activity of yolk was recovered in a supernatant after centrifugation of yolk diluted six- to tenfold with water. The remaining yolk pellet had excellent emulsifying properties for mayonnaise preparation. It was further fractionated by deoxycholate treatment to separate triglycerides (80% recovery). Ultrafiltration of the deoxycholate supernatant yielded protein (74% recovery) in the retentate, and phospholipids and cholesterol in the permeate. Phospholipids were then purified by dich-loromethane:ethanol (3:1) extraction, zinc chloride precipitation and acetone washing.     

新型细菌磷脂酶改性蛋黄卵磷脂

蛋黄中含有丰富的磷脂 ,包括卵磷脂和磷脂酰乙醇胺。磷脂具有非常好的乳化性能 ,并能够通过酶法变性 ,譬如利用磷脂酶A2 生产 2 溶血磷脂 ,该物质与天然磷脂相比 ,具有更好的乳化性能。经过磷脂酶A2 变性的蛋黄就可以用于各种食品的生产 ,而有些食品对乳化性能的要求非常苛刻。LysoMax○R酶是一种非基因改造的细菌磷脂酶A2 ,这种酶能够使蛋黄充分变性 ,并且对其他富含磷脂的底物如大豆卵磷脂和玉米卵磷脂也非常有效。     

Characterization of Water Soluble Egg Yolk Proteins with Isoelectric Focusing

Separation and characterization of some water-soluble egg yolk proteins such as livetins and phosvitins were carried out by isoelectric focusing (IEF). The isoelectric points (IP) of phosvitins were in the pH-range of around 4, those of the livetins were in the range of 4.3 ? 7.6. There are occurring differences between the bands of α, β- and γ-livetins. While the first mentioned had an amount of bands in the pH range 4.3-4.7, the γ-livetins indicated only a few. Above that, a large number of bands can be noted in the range 5.3 to 5.5 referring to the α, β-livetins whereas none can be found when regarding the γ-livetins.     

Electrophoretic and Chromatographic Changes in Egg Yolk Proteins Due to Heat

Polyacrylamide gel electrophoresis and diethylaminoethyl-cellulose ion-exchange chromatography were used to observe changes in egg yolk products which were heat treated at 3°C intervals from 54 to 84°C for 3.5 min. The USDA pasteurization temperatures of 61.0, 63.3°C for plain, 10% sugared, and 10% salted egg yolk, respectively, had little effect on their electrophoretograms. Only the γ-livetins in plain yolk were slightly affected. Higher temperatures progressively altered these proteins until they disappeared from the electrophoretograms from plain yolk ca 73°, sugared yolk ca 76°, and salted yolk ca 79°C. The lipovitellin fraction and phosvitins were similarly affected by increasing temperatures. Sugar and salt at 10% levels had a protective effect against heat, allowing respectively ca 3° and 6°C higher temperatures before heat damage occurred. The chromatograms from plain and sugared yolk were little affected by pasteurization. However, major changes were noted between unheated and pasteurized (63.3°C) salted yolk. Patterns for salted yolk, pasteurized at 63.3 and 68.0°C were similar, which further indicated that this product can be pasteurized at 68.0°C without significant damage.     

Immunoglobulins from Egg Yolk: Isolation and Purification

Simple water dilution was employed for the separation of water-soluble plasma proteins from egg yolk granules. An optimum recovery of immunoglobulin Y (IgY, 93–96%) in water-soluble fraction was obtained by sixfold water dilution at pH between 5.0–5.2 with incubation time of 6 hr at 4°C. Among the factors studied, pH was found to be the most important factor affecting IgY recovery. Active IgY of high purity with good recovery was obtained by a combination of several techniques including salt precipitation, alcohol precipitation, ultrafiltration, gel filtration and ion exchange chromatography. Salt precipitation, ultrafiltration, and get filtration is the recommended sequence. Over 100 mg of electrophoretically pure IgY was routinely obtained from one egg.     

β—环糊精脱除蛋黄液中胆固醇的三种工艺流程比较

本试验在Ｓｍｉｔｈ等的研究基础上,确证β—环糊精脱除蛋黄液中胆固醇的最佳工艺流程为：蛋黄液→稀释→调整→ｐＨ值→加热至５０℃→加β—环糊精→混合１０ｍｉｎ→冷却至４℃,静置１ｈ→以３５００ｒ／ｍｉｎ离心１０ｍｉｎ→取上层液→干燥。该流程可避免蛋黄发生胶凝化作用,便于操作,并在产品中保持了较多的磷脂成分     

Purification of Antibodies from Industrially Separated Egg Yolk

Industrially separated egg yolk was diluted and water soluble proteins separated by sedimentation. The supematant was filtered and applied to a column packed with cation exchanger within an automated liquid chromatography system. This was scaled-up from a 50 mL to a 1500 mL column. Two cation exchangers were investigated and immunoglobulin recoveries of 60–65% were obtained with 60–69% purities. Batch separation resulted in lower recovery (55%) and purity (57%). Further purification was investigated using anion exchange chromatography and salt precipitation. Results were improved with one step salt precipitation where purity was increased. The process is simple, economical and should prove useful for large production of IgY.     

蛋黄卵磷脂的提取方法研究

以鸡蛋黄为原料,采用乙醇提取法提取其中的卵磷脂,设计了四因素正交试验。结果表明,在蛋白酶添加量0.06%,乙醇浓度90%,提取温度25℃,提取时间60min条件下,提取卵磷脂效果最佳。     

Transparent and Edible Films from Ultrasound-Treated Egg Yolk Granules

Whole egg yolk can be easily separated into two fractions, plasma and granules, the former of which is rich in lipids and the latter has a high protein content. Searching for new applications for each fraction could increase the value of the whole egg. In this work, the egg yolk granule fraction is being proposed and used to create transparent, edible films. For that purpose, a solution of egg yolk granules was pre-treated using high intensity ultrasound. A Box-Behnken design was established to determine the effect of temperature, ultrasound intensity and the pre-treatment time on the clarity of the granules solution and the transparency of the films obtained. Furthermore, the films were analysed to test the effect of the ultrasound pre-treatment on their mechanical properties, solubility, colour, thermal stability and structure. The optimal conditions for obtaining highly transparent films from egg yolk granules solution were found to be the following: 45 °C, for 40 min and applying ultrasounds at 60% amplitude. With this pre-treatment, the puncture strength value of the films improved from 9 N/mm, in the case of the untreated granules solution, to 31.6 N/mm. The puncture deformation showed a similar trend. All the films made with egg yolk granules showed a low water solubility. The colour of the films was not affected by the ultrasound pre-treatment.     

酶解超声辅助卵磷脂的提取工艺

以蛋黄粉为原料,采用酶解超声辅助法对卵磷脂进行提取。考察了超声温度、时间、乙醇浓度及溶剂用量四个因素对蛋黄卵磷脂提取的影响,并通过正交实验对提取工艺进行优化。最终确定卵磷脂提取最佳工艺为:酶浓度6.25 mg/mL、超声频率35 kHz、温度35℃、时间30 min、乙醇浓度90%、料液比1∶12(g/mL),此时卵磷脂的提取率为80.64%。     

Effect of pH and Food Ingredients on the Stability of Egg Yolk Phospholipids and the Metal-Chelator Antioxidant Activity of Phosvitin

Egg yolk phosvitin has been previously shown to inhibit metal-catalyzed phospholipid oxidation. In this study, a phospholipid emulsion system was used to study the effect of pH and food ingredients on the antioxidant activity of phosvitin and the oxidative stability of yolk phospholipid. Oxidation of phospholipids was carried out at five different pH levels (3.0, 5.0, 5.7, 6.1, and 7.8). NaCl and freeze-dried egg albumen were incorporated into the pH 6.1 emulsion. Lipid oxidation was measured by the thiobarbituric acid (TBA) assay. Phospholipids were stable at pH 6.1 and 7.8. However, phosvitin was unable to inhibit Cu²⁺ catalysis at pH 7.8. Neither NaCl nor albumen affected the stability of phospholipids or the activity of phosvitin in inhibiting Fe²⁺ catalysis at pH 6.1.     

蛋黄磷脂的制备及脱色工艺的研究

蛋黄磷脂的纯度、提取率和色泽是评价提取效果的关键指标,为得到色泽浅,提取率、磷脂含量高的产品.本试验以磷脂蛋白粉为原料,采用乙醇为溶剂,中性活性炭为脱色剂制备蛋黄磷脂.确定了乙醇提取蛋黄磷脂的较优条件,并对活性炭脱色试验进行优化.试验结果表明,在乙醇浓度为95%,物料与乙醇比为1:7(w/v),提取时间为40 min,提取温度30℃条件下,可以得到提取率及纯度较高的蛋黄磷脂.利用活性炭脱色,结果表明,在活性炭添加量为4%,脱色时间60 min,脱色温度45℃的条件下,脱色率达到96.47%,得到提取率为23.48%,磷脂含量为95.26%的淡黄色蛋黄磷脂.通过此技术,可制得色泽好,提取率和纯度较高的优质蛋黄磷脂.     

Isolation and Characterization of Major Apoproteins from Hen's Egg Yolk Granule

Different patterns were obtained from granular and plasma fractions of egg yolk by SDS-polyacrylamide gel electrophoresis. Three major components of granular apoprotein which constitute 19.4, 14.5, and 43.4% of the protein moiety with estimated molecular weights of 28,000, 74,000, and 109,000 daltons, respectively, were isolated by preparative SDS-gel electrophoresis. They were found to be glycoproteins containing mannose, galactose, and hexosamine. Sialic acid was found only in the 74,000 and 109,000 dalton components. Phosphorus content of the 28,000, 74,000, and 109,000 dalton components were 2.0, 1.2, and 0.4%, respectively.     

Sialyloligosaccharides of Delipidated Egg Yolk Fraction

Delipidated egg yolk (DEY) was homogenized and centrifuged. The supernatant was dialyzed by ultrafiltration using a molecular weight cut-off of 1,000. The asparagine-linked oligosaccharides in the concentrate were liberated from protein by hydrazinolysis and labeled with UV-absorbingp-amionbenzoic ethyl ester (ABEE). The ABEE-derivatized oligosaccharides were fractionated by anion exchange and reverse-phase HPLC. The total sialyloligosaccharides from the water-soluble DEY fraction, were about 47.7% monosialyl and 50.6% di-sialyloligosaccharides. The structures of 3 predominant sialyloligosaccharides were determined by NMR. They were of the biantennary complex-type, accounting for about 33.6% of the total sialyloligosaccharides of the DEY water-soluble fraction.     

Cholesterol Content and Functionality of Plasma and Granules Fractionated from Egg Yolk

In low-salt aqueous solution, nonspray-dried (NS) and spray-dried (SD) egg yolk were fractionated into granule and plasma fractions using ccntrifugation. The following determinations were made on each fraction: total cholesterol, lipid, protein, emulsifying activity (EA) and stability, foam capacity and stability, and protein solubility index. Fractionation of NS to granules resulted in -30% reduction (p ≤ 0.01) in cholesterol, a 46% reduction in lipid, and a twofold increase in protein. In decreasing order (p ≤ 0.01), EA of NS products in distilled water was: plasma > NS > granules. Emulsion and foam stability values exhibited by granules of NS suggest they could be used as a stabilizer of dispersion system.     

Fractionation and Characterization of Hen's Egg Yolk Phosvitin

TWO methods for phosvitin preparation were evaluated, based on purity of the products. Phosvitin was found to be heterogeneous in the polyacrylamide-gel electropherogram in which it migrated into two components designated α and β-phosvitin. They were partially fractionated using gel filtration. The β-phosvitin contained 9.20% phosphorus, while α had 2.97%. Phosvitin was dissociated into several bands ranging in molecular weights from 18,500—60,000 daltons, in the SDS polyacrylamide-gel electropherogram. Results indicate that phosvitin is composed of several subcomponents or polypeptides which interact or polymerize in aqueous solution to form larger molecular weight aggregates.