Processing and Sensory Evaluation of Scrambled Eggs Containing Defatted Yolk Solids

Egg yolk solids defatted with hexane were incorporated into frozen and spray-dried scrambled egg products. Part of the egg oil removed was replaced with nonfat oil replacers. Both products were evaluated by sensory panels. The frozen product was compared with frozen whole egg and a nonyolk, commercial frozen product. The spray-dried product was compared with a nonyolk, commercial dried product. In the frozen products, the whole egg was preferred over both the defatted frozen product and nonyolk, commercial frozen product, with the defatted and nonyolk products being equally acceptable. In the dried products, the spray-dried scrambled eggs were preferred over the nonyolk, commercial dried product. The products formulated from defatted yolk solids contained 84% less lipid and 79% less cholesterol than products made from fresh whole eggs.     

SMALL DEFORMATION PROPERTIES OF MODEL SALAD DRESSINGS PREPARED WITH REDUCED CHOLESTEROL EGG YOLK

Low-fat, low-cholesterol materials were extracted from spray-dried egg yolk using as solvents petroleum ether, petroleum ether/ethanol, ethanol/water, and supercritical CO₂. The four extracts and their source (spray-dried yolk) were incorporated into traditional recipes for oil in water salad dressings. The linear viscoelasticity of these systems was characterised by dynamic oscillation and creep/relaxation curves on a stress-controlled Carri-Med rheometer. The high protein content of the extracts generates stronger and more elastic structures than those of commercial salad dressings but they are comparable to the viscoelastic properties of commercial mayonnaises which contain high cholesterol egg yolk. Measurements of the size of oil droplets over a period of eleven days demonstrate that these emulsions maintain acceptable consistency. The methodology adopted and the conclusions derived might assist in the purposeful formulation of low-cholesterol salad dressings.     

Cholesterol Oxidation in Egg Yolk Powder During Storage and Heating as Affected by Dietary Oils and Tocopherol

The effects of feeding flax, sunflower, palm and fish oils, with and without tocopherols, to laying hens was investigated on oxidative stability of cholesterol in egg yolk powders. Storage of spray-dried egg yolk powders at room temperature resulted in loss (p <0.05) of tocopherols. The initial levels of spray-dried yolk cholesterol oxides were 7–10 ppm and increased (p <0.05) with storage. The cholesterol oxide contents in the egg yolk powders were: fish > flax > sunflower > palm. Heating egg yolk powder increased (p <0.05) the amounts of total cholesterol oxides. Diets with tocopherol supplementation resulted in a decrease (p <0.05) of cholesterol oxides during storage and heating.     

SMALL DEFORMATION MEASUREMENTS OF SINGLE AND MIXED GELS OF LOW CHOLESTEROL YOLK AND EGG WHITE

Isolates of reduced-cholesterol egg yolk were prepared by extracting cholesterol from spray-dried yolk using the following solvents: (1) petroleum ether, (2) petroleum ether/ethanol, (3) ethanol/water and (4) supercritical carbon dioxide. Differential scanning calorimetry demonstrated that the temperature of minimum heat flow of the denatured isolates was about 75C. Mechanical properties of extracts were compared using small deformation oscillatory rheology. Ethanol/water and petroleum ether treated yolk had the strongest and weakest gelling characteristics respectively, following protein denaturation at 75C. When compared to egg white, yolk isolates formed stronger networks at 75C. Heating at higher temperatures denatured ovalbumin which produced slightly stronger gels than egg yolk. Binary mixtures of egg white and yolk formed phase separated gels. The best agreement between experimental data and calculated composite moduli by using isostrain and isostress Takayanagi models, was obtained for egg white keeping 37% more water per unit concentration than the egg yolk.     

Production of phospholipids from spray-dried egg yolk by consecutive in situ solid phase extraction with acetone and ethanol

Egg yolk lipids were extracted and fractionated into neutral lipids and phospholipids using acetone followed by ethanol as eluting solvents to a column consisting of spray-dried egg yolk. This technique, named in situ solid phase extraction, can be performed with spray-dried egg yolk due to the properties of this material. The effect of temperature, flowrate and scale has been studied. Results suggest that the methodology is suitable for industrial implementation.     

Effects of spray-dried whole egg and biotin in calf milk replacer

Holstein bull calves (n = 120) were fed milk replacers containing 0, 10, or 20% of the formulation (0, 22, or 44% of crude protein) as spray-dried whole egg powder in a 56-d feeding trial. Milk replacer was medicated with oxytetracycline and neomycin and was fed from d 1 to 42 of the study in a phase-fed program. All experimental milk replacers were supplemented with B vitamins, except biotin. One half of all calves were supplemented with 1 mg/kg of supplemental biotin to determine whether avidin in the egg protein product inhibited growth. Increasing spray-dried whole egg caused a linear reduction in body weight, body weight gain at 28 and 56 d of the study, calf starter intake, and feed efficiency. Calves fed milk replacers containing 0, 10, and 20% spray-dried whole egg gained an average of 486, 369, and 302 g/d, respectively, during the 56-d trial. Efficiency of feed utilization was 446, 318, and 231 g of body weight gain per kilogram of dry matter intake. Improvement in body weight and feed efficiency occurred when calves began consuming calf starter on d 29. Digestibility of protein or fat from egg may have been reduced during the trial; however, the addition of biotin to the milk replacer did not influence animal performance, suggesting that avidin in spray-dried whole egg was not responsible for impaired performance. The spray-dried whole egg product used in this study did not provide nutrients to support adequate growth of milk-fed calves.     

The effect of storage on the proteins of frozen liquid egg and spray-dried egg

Storage of spray-dried whole egg and egg-milk mixture for about a year at 3–5°C resulted, in both cases, in a marked reduction in the proportion of insoluble proteins and an equally marked increase in the inert lipoprotein fraction of the soluble proteins; this fraction was clearly derived from the low density fraction of the yolk. Storage of frozen liquid egg for about a year in the frozen state resulted in the insoluble protein fraction of the thawed egg having more water bound in it than did the corresponding fraction of the freshly-frozen egg, but in neither case did the insoluble proteins have as much water bound with them as those of the reconstituted spray-dried samples. Spray-drying results in only a partial reduction in the contents of ovalbumin, ovomucoid and conalbumin, and addition of milk to the whole egg before spray-drying improves the stability of these proteins. They appear to be little changed by freezing and storing in the frozen state. There is evidence that ovalbumin is present in a more stable form in processed egg products than in new-laid raw egg.     

Rheology of spray-dried egg yolk-stabilized emulsions

This paper deals with the influences that concentrations of oil fraction (65–77.5% w/w) and egg yolk (1–5% w/w), as well as temperature (5–35 °C), exerted on the droplet size distribution and rheological functions of concentrated oil-in-water food emulsions that were stabilized by a spray-dried egg yolk product. This work must be considered as a preliminary study concerning the use of low-in-cholesterol egg yolk as emulsifier. In order to achieve this aim, steady-state flow and dynamic viscoelasticity tests were done with emulsions processed with a rotor-stator turbine. The same processing conditions were always maintained. All of the emulsions prepared showed a high stability. An increase in oil fraction yielded higher values for the rheological functions, and larger droplet diameters. The influence of processed egg yolk concentration was more complex. Thus, an increase in egg yolk content yielded lower values for the rheological functions, but, after a particular concentration, a further increase in emulsifier content yielded higher values for the rheological functions. The experimental results have been discussed taking into account the close relationship between rheology and emulsion structural parameters.     

Effects of spray-drying and freezing on the proteins of liquid whole egg

Commercial pasteurised liquid whole egg was spray-dried, both alone and mixed with liquid milk, and some of it was frozen. Paper electrophoresis revealed that lipoprotein fractions from the pasteurised liquid egg were mainly immobile, in contrast to unpasteurised new-laid egg which contained both mobile and immobile lipoprotein fractions. The major difference between the soluble proteins of the commercial chilled pasteurised liquid egg and those of the same egg after freezing and thawing was the presence, in the former, of an inert lipoprotein fraction, amounting to 3.6% of the total egg solids and containing 88% lipid. The “soluble” proteins of spray-dried egg and egg-milk mixture also included large “inert” lipoprotein fractions eluted with the void volume. They contained 72–81% of lipid and accounted for 7–13% of the total egg solids. Larger fractions were eluted by the stronger salt buffer solutions and by hydrochloric acid from the dried egg-milk mixture than from the dried egg, and these were probably derived from the milk. All the spray-dried samples possessed the “inert insoluble” protein fraction characteristic of liquid egg, and the presence of a high molecular weight lipoprotein fraction was confirmed in each case. The “insoluble proteins” of the spray-dried samples had higher protein contents than those from the original chilled liquid egg and the thawed frozen egg.     

In situ solid phase extraction of lipids from spray-dried egg yolk by ethanol with subsequent removal of triacylglycerols by cold temperature crystallization

ln situ solid phase extraction of lipids from spray-dried egg yolk by ethanol combined with subsequent removal of triacylglycerols from the ethanolic extract by cold temperature crystallization is described. By this procedure a lipid product is obtained which contains 86 g/l00 g phospholipids, 4 g/l00 g triacylglycerols and 10 g/100 g cholesterol. About 80% of spray-dried egg yolk phospholipids are recovered in this product. The product may serve as a source of phospholipids for specialized dietetic applications due to their relative high contents of both n-3 and n-6 long-chain polyunsaturated fatty acids. The procedure which requires no mechanical extractor and filtering device is amenable to scale up since recovery is not affected by changes in column volume or flow rate. This suggests the possibility of profitable industrial exploitation.     

蛋黄卵磷脂的提取方法研究

为探讨从蛋黄中提取蛋黄卵磷脂的方法。试验以蛋黄为原料,采用有机溶剂和酶解法从蛋黄中提取卵磷脂粗品,然后分别经柱硅胶层析和金属离子沉淀法纯化获得卵磷脂精品,通过测定卵磷脂的含磷量,判断其纯度高低。结果显示:采用有机溶剂法获得蛋黄卵磷脂粗品,然后经柱硅胶层析纯化可获得高纯度蛋黄卵磷脂精品,总得率为8.38%,卵磷脂的含磷量为15.33%。是一种高效、经济的蛋黄卵磷脂提取方法。     

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.     

Effect of garlic powder on the performance,egg traits and blood parameters of laying hens

This study was conducted to investigate the effects of garlic powder on the performance, egg traits and blood parameters of laying hens. One hundred and sixty‐two SHSY‐type brown layers aged 21 weeks were chosen at random from a large flock. They were allocated to three dietary treatments. Each treatment comprised six replicates of nine layers in groups of three. The diets were supplemented with 0, 5 and 10 g kg^?1 garlic powder. The experimental period lasted 22 weeks. Garlic powder addition did not significantly affect body weight, egg production, feed consumption, feed efficiency, egg shell index, egg breaking strength, egg shell thickness, egg albumen index, egg yolk index, egg Haugh unit, egg yolk weight and serum protein concentration. Egg weight increased (P < 0.01) with garlic powder supplementation. There was a significant (P < 0.01) reduction in egg cholesterol concentration as mg g^?1 yolk when the dietary level of garlic powder was increased from 0 to 10 g kg^?1. Hen serum triglyceride (P < 0.05) and total cholesterol (P < 0.01) concentrations decreased with garlic powder supplementation. This study demonstrated that garlic powder addition increased egg weight and decreased egg yolk cholesterol concentration (mg g^?1 yolk) and serum triglyceride and cholesterol concentrations without adverse effects on performance and egg traits. Copyright © 2006 Society of Chemical Industry     

A Lipoprotein-derived Antimicrobial Factor from Hen-egg Yolk is Active Against Streptococcus Species

ABSTRACT: Oral administration of hen-egg yolk provides protection against specific pathogens. We examined the antibacterial activity of fractionated egg yolk against 2 pathogenic Streptococcus strains, using an in vitro assay. A water-soluble protein fraction (WSPF) of egg yolk consistently inhibited the growth of S. mutans by 25%. The WSPF treated with pancreatin demonstrated > 80% inhibition of bacterial growth. Growth of S. sanguis was completely inhibited. Gel filtration and ion exchange chromatography established that anti-Streptococcal activity resided with lipoproteins. Antibacterial activity was released by crude lipase or a combination of lipase and protease treatment of egg lipoproteins. Thus, hen-egg yolk lipoproteins are important molecules for lipid-mediated antimicrobial activity.     

The effects of sources of supplemental fat on performance,egg quality,and fatty acid composition of egg yolk in laying hens

BACKGROUND: The objective of this study was to determine the effects of sources of supplemental fat on laying performance, egg quality, and fatty acid composition of egg yolk. RESULTS: Two hundreds Isa Brown layers were assigned randomly to be fed ad libitum a standard commercial layer feed (BD), basal diet plus 2% tallow (T), basal diet plus a mixture of 1% tallow and 1% flaxseed oil (MTFO), basal diet plus 2% sunflower oil (SO), or basal diet plus 2% flaxseed oil (FO), which were offered for 8 weeks. Each diet was given to five groups, each containing 10 hens. The feed efficiency and egg production were 2.78 and 53.51% for BD; 2.30 and 63.47% for T; 2.45 and 60.14% for MTFO; 2.29 and 64.30% for SO, and 2.62 and 61.18% for FO groups, respectively. Dietary fat supplementation affected the laying performance but had no significant effects on egg quality parameters. The fatty acid composition of egg yolk lipids were significantly affected by dietary fatty acid composition. The supplemental tallow increased palmitic fatty acid. The proportions of linoleic and arachidonic fatty acids in egg yolks for layers fed the SO diet were higher than in the BD group and those on diets containing other fats. Concentrations of oleic and omega‐3 fatty acids were the highest in layers fed the FO diet during the laying period. CONCLUSION: The results indicated that dietary animal and plant fats changed the fatty acid composition of egg yolk. Copyright © 2008 Society of Chemical Industry     

The effect of a hypocrellin A enriched diet on egg yolk quality and hypocrellin A distributions in the meat of laying hens

Hypocrellins, including hypocrellin A and hypocrellin B, are natural red pigments isolated from a traditional Chinese medicine. The present work was designed to investigate the influence of dietary HA supplementations on the colour and emulsifying properties of egg yolk and HA distributions in tissues of laying hens. A Chinese hen breed (black-bone silky fowl) was used. Ninety-six layers were assigned randomly to diets containing 0, 10, 30 and 50 mg HA per kilogram for 21 days. HA concentrations in egg yolk and tissues of laying hens such as ovary, liver, lung, heart, gizzard and breast muscle were determined by HPLC. Dietary HA supplementations improved the colour of egg yolk (P < 0.05), whereas no significant differences (P > 0.05) in the emulsifying properties of egg yolk were observed. There was a dose-dependent manner increase in egg yolk HA content in response to dietary HA supplementations (P < 0.05). The highest HA concentration was measured in ovary followed by liver and egg yolk.     

Detection of Salmonella Enteriditis from Egg Components Using Different Immunomagnetic Beads and Time-resolved Fluorescence

The types of chemical linkage used to bind antibodies to magnetic beads to form immunomagnetic beads (IMB) were compared in the capture and detection of Salmonella Enteriditis from egg white, egg yolk, and whole egg. Egg components were inoculated with outbreak strains of S. Enteriditis. After incubation under different conditions, IMBs derived from linking antibodies to core magnetic beads via biotin–streptavidin interactions, Schiff-base bonds and unspecified proprietary chemistry were used to capture S. Enteriditis. Europium-labeled anti-Salmonella antibodies completed the sandwich, and time-resolved fluorescence served as the means of detection. For the Salmonella isolated in stationary phase and cultured from universal pre-enrichment broth (UPB), the detection signal intensity was affected by the chemistry utilized to link the antibodies to IMB, with results varying among the three test strains. When S. Enteriditis was cultured in egg yolk alone, plating data were similar to those of the growth of S. Enteriditis in UPB. Egg white by itself did not support the growth of S. Enteriditis. The addition of UPB to egg white restored the growth of Salmonella and yielded stronger detection signals than from cultures obtained from UPB with egg yolk. The detection signals obtained from the immunoassay were less intense for cultures grown in egg yolk + UPB than from cultures grown in UPB alone. The lower detection signals elicited by all IMBs suggest the availability of the antigenic groups recognized by the antibodies on IMBs was reduced in the presence of egg yolk.     

A simple chemical method for identification of irradiated industrial processed food

The dependence of o- and m-tyrosine levels in protein rich products upon the absorbed radiation dose offers the possibility for identification of radiation processed foodstuffs. A simple and fast method was applied for determining irradiation of industrial processed food. Free amino acids of irradiated and unirradiated liquid egg samples (liquid egg, liquid egg yolk) and homogenized turkey sausage samples were extracted with trichloroacetic acid. After centrifugation and filtration aliquots of the crude extract were applied for HPLC analysis using a RP-C18 column and trichloroacetic acid as ion-pairing agent in combination with an electrochemical dual cell detector. o- and m-Tyrosine were identified by relative retention times and their peak height ratios at different potentials in comparison to those of a standard mixture and quantified by calibration curves. The commercial products investigated were unirradiated.     

Cumin seed meal as an alternative to wheat bran in commercial laying hen diets

To evaluate the nutritional significance of cumin seed meal (CSM) as a commercial poultry feedstuff on laying hen performance and quality of laid eggs, an experiment was conducted using 144 (48‐week‐old) laying hens receiving diets containing 0, 25 and 50 g CSM kg^?1 with or without polyethylene glycol (PEG 6000) and xylanase enzyme (Grindazym^? GP 15000) for 9 weeks. Body weight on the first and last days of the experiment and daily egg production and egg weight and weekly feed intake during the first, fifth and ninth weeks of the experiment were recorded. Shell weight, shell thickness, Haugh unit and yolk colour were measured during the last week of the experiment. The results showed that inclusion of CSM in laying hen diets had no negative influence on the parameters measured compared with the control diet (P > 0.05), but enhanced egg yolk colour (P < 0.05). PEG increased the daily feed intake of birds receiving CSM diets (P < 0.01) and tended to enhance daily egg production and egg weight, although not significantly. Grindazym decreased shell weight and thickness of laid eggs (P < 0.05) and tended to increase hen body weight, but had no influence on other parameters measured. The results demonstrated that CSM can be substituted for wheat bran in layer diets at 25 or 50 g kg^?1 dietary inclusion level without any adverse effect on hen performance or egg quality, and might enhance egg yolk colour. In view of the low price of CSM, it could be concluded that inclusion of CSM in the diet might be beneficial to the commercial laying hen industry and reduce the overall cost of egg production. Copyright © 2006 Society of Chemical Industry     

Comparative study on physicochemical and functional properties of egg powders from Japanese quail and white Leghorn chicken

Physicochemical and functional properties of freeze-dried egg powders (egg white, egg yolk, and whole egg) from Japanese quail and white Leghorn chicken were studied comparatively. All egg powders had protein content in the range of 91.13–97.03 g/100 g powder. The quail egg powder had higher mineral and essential amino acid contents, but lower fat content as compared to chicken egg powders (P < 0.05). Moreover, egg white powder from both quail and chicken presented higher total amino acids content than corresponding whole egg and egg yolk powders, respectively. Fourier transform infrared spectroscopic study revealed that β-sheet is the major secondary structure of all egg powders. Based on differential scanning calorimetry analysis, quail egg powders showed slightly lower denaturation temperatures than corresponding chicken egg powders (P < 0.05). Sodium dodecyl sulfate–polyacrylamide gel electrophoresis study showed the slight difference in protein patterns of corresponding quail and chicken egg powders. The quail egg powders presented higher protein solubility than corresponding chicken egg powders at all pH tested. Furthermore, quail egg powders exhibited higher emulsion activity index and emulsion stability index with higher foam expansion and stability than the corresponding chicken egg powders. Therefore, Japanese quail egg powders could be used as an alternative to white Leghorn chicken egg in the preparation of foods and diets that require high protein content with positive health benefits.