• Asian-Australasian Journal of Animal Sciences
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• v.4 no.4
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• pp.399-405
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• 1991

The interaction of 4 dietary crude protein (13, 16, 19 or 22%) and 4 metabolizable energy (2600, 2800, 3000 or 3100 kcal ME/kg) levels on egg quality performances of Starcross layers were assessed between 245 and 275 days of age. The egg weight increased significantly with the increasing dietary protein and energy levels. But egg shape index, albumen index, yolk index, yolk dry matter, yolk protein, yolk fat, albumen protein and shell tickness were similar at all dietary protein and/or energy levels. The egg specific gravity and albumen weight increased but the yolk, weight, Haugh unit and albumen drymatter decreased with the increase of dietary protein levels and showed irregular trend with energy levels. The albumen dry matter and egg shell weight, however, were not affected by energy and protein levels. Simultaneous increase of protein and energy increased specific gravity, albumen index and shell thickness at a greater rate than that increased by the increase of protein or energy alone.

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.6
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• pp.881-890
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• 2019

Objective: A study was conducted to develop non-dairy creamer analogs/mimics using egg white, egg yolk, soy protein and their combinations, and their nutrient content, shelf-life and flavor acceptability were compared. Methods: Spray dried egg white, egg yolk, and soy protein isolate were purchased from manufacturers and used for the formulae. Results: The protein contents of the non-dairy creamer analogs/mimics were about 8.5% as calculated. The amounts of oleic and linoleic acid content increased as the amount of yolk increased in the formula, but the increases of polyunsaturated fatty acids were <0.5% of total fat. Addition of egg yolk to the formula increased choline and lutein content in the products, but the amounts were <0.4 mg/g for choline and $4{\mu}g/g$ for lutein. The lutein in the products continued to decrease over the storage time, and only about 15% to 20% of the 0-month amounts were left after 3 months of storage. Although the thiobarbituric acid reactive substances values of the spray-dried non-dairy creamer analogs/mimics increased as storage time increased, the values were still low. Yellowness, darkness, and egg flavor/odor of the non-dairy creamer analogs/mimics increased as the amount of egg yolk in the formula increased. The overall acceptability of the non-dairy creamer analogs/mimics was closely related to the intensity of egg flavor/odor, but storage improved their overall acceptance because most of the off-odor volatiles disappeared during the storage. Water temperature was the most important parameter in dissolving spray-dried non-dairy creamer analogs/mimics, and $55^{\circ}C$ to $75^{\circ}C$ was the optimal water temperature conditions to dissolve them. Conclusion: Higher amounts of yolk and soy protein combinations in place of egg white reduced the cost of the products significantly and those products contained better and balanced nutrients than the commercial coffee creamers. However, off-flavor and solubility were two important issues in the products.

• Food Science and Biotechnology
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• v.15 no.2
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• pp.189-195
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• 2006

A study was conducted to develop optimal conditions for a large-scale, sequential separation method for value-added components from egg yolk. Starting with liquid egg yolk, immunoglobulin Y (IgY), phospholipids, and neutral lipids were extracted sequentially using water, ethanol, and n-hexane. The remainder was yolk proteins. Adjusting the pH of diluted egg yolk to pH 5.0-5.2 decreased phospholipids content in the supernatant after centrifugation, which was very important for preventing clogging problem of ultrafiltration filters during the subsequent concentration step for IgY separation. Extraction of precipitants after centrifugation with four volumes of 100% ethanol once removed most of the phospholipids and the purity of phospholipids was more than 85% (wt.) after drying. The subsequent extraction of precipitant from ethanol extraction with four volumes of hexane 3 times removed neutral lipids almost completely and resulted in a high protein product with minimal lipids. The sequential separation method is considered to be advantageous for large-scale separations of many valuable components from egg yolk.

• Journal of Life Science
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• v.10 no.2
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• pp.131-139
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• 2000

Lecithin-free egg yolk protein (EYP), the by-product of lecithin extraction from egg yolk, which is denatured with an organic solvent, would normally be discarded. In this study, the denatured protein was renatured with alkali, and hydrolyzed with Alcalase in order to utilize by-product. The hydrolysate was separated through a series of ultrafiltration membranes with molecular weight cut-off (MWOO) of 10, 5 and 1 kDa, and the antioxidative activities of the hydrolysates was investigated. The 5K hydrolysate, permeate from 5 kDa membrane, showed stronger antioxidative activity than 10 K and 1 K hydrolysate which were permeated from 10 kDa and 1 kDa membrane, in a linoleic acid autoxidation system. In addition, the optimum concentration of antioxidative activity for 5 K hydrolysate was 1%, and the activity was about 37% higher as compared with α-tocopherol. The synergistic effect was also increased by using the hydrolysates with α-tocopherol.

• Journal of the East Asian Society of Dietary Life
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• v.20 no.1
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• pp.77-83
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• 2010

The study was conducted to investigate the effect of particle size on the physicochemical properties of egg yolk-rice porridge. The pH of egg yolk-rice porridge was decreased when compared to that of the control, while the lightness and yellowness was increased as the rice particle size increased. The viscosity of whole particle egg yolk porridge was highest among the three porridges at $40^{\circ}C$. The protein content of the egg yolk-rice porridge was increased three-fold, when compared to that of the rice porridges. The total amino acid content of egg yolk-rice porridge was 1,500.6 mg/100 g, while that of rice was 1,147.5 mg/100 g. The Lys and Thr content of the amino acid content of egg yolk-rice porridge were also increased. Sensory evaluation results revealed that the half particle size rice egg yolk-rice porridge had the highest scores in color, taste and over-all preference. Based on these results, the half particle size egg yolk-porridge had good quality with respect to both the physicochemical and nutritional properties.

• Journal of Aquaculture
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• v.11 no.2
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• pp.271-278
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• 1998

To clarify characteristics of yolk protein of abalone, yolk protein was purified from the ovarian egg extracts of mature female Haliotis discus hannai by a gel chromatography of sepharose CL-4B. From the results of immuno-electrophoresis and Ouchterlony's diffusion test to male and female sera and ovarian egg extracts using antibodies raised against mature female and male sera and male sera and ovarian egg extrascts, it was identified that the mature female serum had female specific serum protein and its antigenecity shared with ovarian egg extracts. A single type of yolk protein was purified from ovarian egg extracts, and it was composed of two subunits. Their molecular weights were estimated to be approximately 166 KDa and 113 KDa by SDSPAGE. The antiserum against yolk proteins cross-reacted with a mature female specific serum protein and extracts of hepatopancreas of vitellogeing females, but did not reacted with extracts of hepatopancreas of mature male.

• Food Science of Animal Resources
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• v.42 no.2
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• pp.321-331
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• 2022

Egg yolk is widely used to extract lecithin, which is utilized in the food and cosmetics industry. After lecithin is removed, the rest of egg yolk is generated as a by-product. Thus, it is necessary to properly utilize it. In this study, egg yolk protein extracts were produced using ethanol (EYE-E) and water (EYE-W). Their antioxidant and immunomodulatory effects were then evaluated. Antioxidant activities of EYE-E and EYE-W were determined using cellular antioxidant capacity (CAC) assay and comet assay. EYE-E and EYE-W showed significant (p<0.05) scavenging effects on intracellular reactive oxygen species (ROS) in a dose dependent manner. At a concentration of 50 ㎍/mL, EYE-W showed higher (p<0.05) antioxidant activity than EYE-E. EYE-E and EYE-W also exhibited protective effects against DNA damage caused by oxidative stress. After treatment with EYE-E and EYE-W, DNA damage level of 48.7% due to oxidative stress was decreased to 36.2% and 31.8% levels, respectively. In addition, EYE-E and EYE-W showed immunomodulatory effects by regulating Th1 cytokines (TNF-α and IL-2) and Th2 cytokines (IL-10 and IL-4) in Balb/c mouse splenocytes. These data suggest that EYE-E and EYE-W could be used as functional food ingredients with excellent antioxidant and immunomodulatory activities in the food industry.

• Korean Journal of Poultry Science
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• v.22 no.3
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• pp.161-166
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• 1995

To evaluate the nutritional values of Spirulina platensis as the protein supplement for laying heo diet, two experimental diets (Control, Spirulina platensis 2%) were prepared. Total 120, 40-wk old ISA Brown layer hens were randomly employed with 15 hens per replicate and 4 replicates per treatment. Hen-day egg production, egg weight, feed intake, intake /egg weight, egg shell thickness, yolk color score and yolk cholesterol content were examined during 6 weeks of experimental period. Hen-day egg production and feed conversion ratio (intake /egg weight) were significantly (P<0.01) improved by the 2% Spirulina plalensis supplementation. However, there were no differences in egg weight and feed intake between hens fed two experimental diets. Egg from hens fed Spirulina platensis 2% diet have more yellowish yolk color than the control egg although there was no difference in egg shell thickness. Yolk cholesterol content was significantly (P

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.485-489
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• 2003

Enzymatic hydrolysis of egg yolk Protein was carried out in continuous packed column reactor Five supports for enzyme immobilization were evaluated in this study. We investigated the optimum operation variables - pH, temperature, and flow rate in continuous reactor operation.

• Korean Journal of Poultry Science
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• v.25 no.4
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• pp.161-167
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• 1998

This experiment was carried out to develope the production of specific yolk antibody from laying hens immunized with antigens from Salmonella enteritidis. Antigenic protein isolated from the flagella of Salmonella enteritidis, determined by SDS-PAGE, was pure and has a molecular mass of approximately 54.6 kDa. It was observed that the antibody titers both in egg yolk and serum were performed at 2 weeks after immunization with flagella antigen to the laying hen. And the level was increased gradually to 6 weeks after immunization. At the time of 6 weeks, the antibody titer of yolk showed higher than that of serum. According to the results of specificity test(ELISA), the yolk antibody did not react with different bacterial strains(S. choleraesuis, ETEC Kl2:K99, K88,987P), but reacted only with S. enteritidis strain. The contents of immunoglobulin(IgY) in an egg yolk was 106mg approximately. By the isolation procedure of IgY from the egg yolk, 88.3 percent of IgY content was recovered in this study.