• Korean journal of food and cookery science
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• v.13 no.2
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• pp.87-91
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• 1997

Egg yolk oil was obtained by roasting and Pressing egg yolks of hen's egg breeding on the open bin system and the cage system, respectively. Lipids in egg yolk oil were extracted with a mixture of chloroform and methanol (2 : 1, V/V), and fractionated into neutral lipid, glycolipid, and phospholipid by silicic aicd column chromatography. Fatty acid composition of each fraction was determined by gas chromatography. The major fatty acids of total lipids and neutral lipids are in sequence of oleic acid, palmitic acid, and linoleic acid. The major fatty acids of the glycolipids are palmitic acid, oleic acid, stearic acid, and lauric acid successively. The major fatty acids of phospholipids are oleic acid, lauric acid, and Palmitic acid consecutively. About the fatty acids composition of egg yolk oil in the open barn system, the contents of saturated fatty acid are lower and the contents of unsaturated fatty acid are higher than that of the case system. The contents of unsaturated fatty acid in egg yolk oil is higher than that of saturated fatty acid in total lipids and nutral lipids. Unsaturated fatty acid/saturated fatty acid of e99 yolk oil in the open barn system is higher than that of the cage system in glycolipids and phospholipids.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.6
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• pp.831-836
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• 2001

Little information on the cholesterol content and the fatty acid composition of avian species other than chicken is available. This study was conducted to compare the yolk cholesterol content and the fatty acid profiles of some wild birds maintained in captivity on commercial grain-based chicken diets. The concentration of cholesterol/g of yolk as well as the total yolk cholesterol per egg varied among species. Yolk cholesterol concentration, expressed as mg/g of yolk, was highest in chukar, followed by pheasant, guinea fowl and quail, while total yolk cholesterol in an egg was highest in guinea fowl, followed by pheasant, chuckar and quail. An inverse relationship between yolk cholesterol concentration and egg weight was observed among species with an exception of quail. Although major fatty acids of egg yolk were oleic acid, palmitic acid, linoleic acid and stearic acid in all birds, the composition varied among species. Chukar and quail showed higher oleic acid content than pheasant and guinea fowl, while showing lower linoleic acid. Fatty acids of chukar and guinea fowl eggs were more saturated than those of pheasant and quail. Chukar and especially quail had higher monounsaturated fatty acids (MUFA) than pheasant and guinea fowl; in quail egg 51.6% of total fatty acids were MUFA. Polyunsaturated fatty acids (PUFA), essential fatty acids (EFA) and the ratio of PUFA to saturated fatty acid (P/S ratio) were higher in pheasant and guinea fowl than in chukar and quail. Differences in fatty acid profile of triglyceride (TG) among birds were largely similar to those of total lipid. In comparison to TG, phosphatidyl choline (PC) was low in MUFA while high in saturated fatty acids (SFA), PUFA, P/S ratio and EFA. PC was most saturated in guinea fowl egg yolk, followed by chukar, quail and pheasant. PUFA, P/S ratio and EFA in PC were highest in pheasant followed by chukar, guinea fowl and quail. PE was distinguished from PC by its high contents of stearic acid, eicosapentenoic acid (EPA) and docosahexenoic acid (DHA) while low in palmitic, oleic and linoleic acids. In egg yolk of all birds MUFA was significantly lower in PE than in PC except in quail. Compared to other species, quail had a considerably higher content of MUFA in PE at the expense of SFA and PUFA.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.1
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• pp.14-19
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• 2001

This study was designed to compare content and composition of fatty acid in egg yolk oil among general eggs from chicken, quail, duck. We also compared those of general and functional chicken egg. Fatty acids were determined by GC method and the results were as follows: Palmitic acid, palmitoleic acid, stearic acid, oleic acid, linoleic acid, linolenic acid and timnodonic acid were identified in egg of chicken, quail and duck. The major fatty acid was oleic acid and palmitic acid in three kinds of eggs. Arachidonic acid and docosahexaenoic acid (DHA) were analyzed in egg of quail , but no in chicken. Monounsaturaterd fatty acid (MUFA) was higher in egg yolk oil of chicken and quail. Polyunsaturated fatty acid (PUFA) was higher in duck egg. Ginseng egg had significantly higher palmitic acid and oleic acid lower than general chicken egg. Gamgoal egg had lower palmitic acid and oleic acid, and higher palmitoleic acid and stearic acid than general chiekcn egg. The content of oleic acid was lower in DHA egg than in general chiecken egg, but arachidonic acid was detected only in DHA egg. Ginseng egg had the highest content of saturated fatty acid among chicken eggs. The content of MUFA acid was the highest in gamgoal egg and general chicken egg. DHA egg had the most amount of PUFA among all chicken egg.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.3
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• pp.391-397
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• 2015

Two hundred and sixteen Institut de S$\acute{e}$lection Animale (ISA) brown layers (40 wks of age) were studied for 6 wks to examine the effect of microalgae powder (MAP) on egg production, egg quality, blood lipid profile, and fatty acid concentration of egg yolk. Dietary treatments were as follows: i) CON (basal diet), ii) 0.5% MAP (CON+0.5% Schizochytrium powder), and iii) 1.0% MAP (CON+1.0% Schizochytrium powder). From 44 to 46 wks, egg production was higher in 1.0% MAP treatment than in control treatment (linear, p = 0.034); however, there was no difference on the egg production from 40 to 43 wks (p>0.05). Serum triglyceride and total cholesterol were significantly reduced in the groups fed with MAP, compared to those in groups fed with control diets (Quadratic, p = 0.034 and p = 0.039, respectively). Inclusion of 0.5% MAP in the diet of layers improved egg yolk color, compared with hens fed with basal diet at 46 wks (quadratic, p = 0.044). Eggshell thickness was linearly increased in MAP-fed treatments at 46th wk (p<0.05). Concentration of yolk docosahexaenoic acid (DHA; C22:6n-3) was increased in treatment groups fed with MAP (linear, p<0.05). The n-6 fatty acids, n-6/n-3 fatty acid, and unsaturated fatty acid/saturated fatty acid were decreased in treatment groups fed with MAP (linear, p<0.05). These results suggest that MAP improved the egg production and egg quality, and may affect serum lipid metabolites in the layers. In addition, MAP increases yolk DHA levels, and deceases n-6/n-3 fatty acid ratio.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.8
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• pp.1165-1170
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• 2003

A total of 250 laying hens were fed a diet containing 0, 1, 2.5 or 5% conjugated linoleic acid (CLA), and 5% Safflower seed oil (SSO) for 5 weeks, and eggs were collected by week to analyse lipid characteristics of egg yolk. Egg yolk from CLA-fed groups showed significant increase in CLA content with increased CLA in the diet. Dietary CLA also increased the ratio of saturated fatty acids and decreased unsaturated fatty acids in the egg yolk. The proportion of myristic, palmitic, stearic and CLA were increased, while those of oleic, linoleic, linolenic and arachidonic acid were decreased. The cholesterol content in egg yolk was significantly decreased by dietary CLA for 5 weeks feeding. After 7 days of feeding, 5% CLA-fed group showed the lowest cholesterol content in egg yolk. CLAfed groups showed significantly lower 2-thiobarbituric acid-reactive substances (TBARS) values compared to control and SSO-fed group after 14 days of storage. No significant differences in TBARS values among CLA-fed groups were observed at the 28 days of storage. Results suggested that lipid oxidation of egg yolk during cold storage could be inhibited by dietary CLA due not only to changes in fatty acid composition but also to the high concentration of CLA in egg yolk.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.5
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• pp.860-865
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• 1997

Investigations were performed on the effects of extraction temperature, pressure, time on solubility and selectivity of egg yolk lipid and cholesterol, and color and fatty acid composition of the residue in supercritical carbon dioxide(SC-Co$_2$) extraction. Lipid and cholesterol solubility increased as the increase of Co$_2$ density and was found to strongly depend on the extraction pressure rather than the extraction temperature. The relative concentration of cholesterol in the extract increased with an increase in temperature and decreased with an increase in pressure and extraction time. extraction of dried eg yolk for 3hr at 4$0^{\circ}C$/276 bar removed 46.1% of cholesterol from the residual egg yolk with a yield of 63.2%. SC-Co$_2$ extraction produced a lighter color egg yolk with less redness and yellowness. As the extraction time increased, the resultant residual egg yolk became more saturated with fatty acids. SC-$CO_2$ extraction offers a safe, natural method for removing cholesterol from dried egg yolk.

• Food Science of Animal Resources
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• v.26 no.4
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• pp.517-524
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• 2006

We investigated the effect of different kinds of dietary fats on the fatty acid composition, cholesterol content and quality of hens' eggs. The Haugh units, breaking strength, shell thickness and yolk color were not significantly different among the test groups. The type of dietary fat fed each test group notably altered the polyunsaturated fatty acid composition and cholesterol content of egg yolk. The n-6 fatty acid content of egg yolk was highest in the corn oil fed group being 31.61%, and this tended to decrease in the tallow, linseed oil and fish oil fed groups(P<0.05) in that order. The n-3 fatty acid content of egg yolk tended to increase in the linseed oil and fish oil fed groups with values of 9.74% and 5.16%, respectively(p<0.05). The increase of n-3 fatty acids in the yolk resulted in a reduced cholesterol content of the eggs. The cholesterol content ranged from $15.98{\sim}18.37mg/g$ of yolk or $227{\sim}261mg/60g$ of egg(p<0.05). The cholesterol content of egg yolk was highest in the tallow fed group, and significantly reduced to 13.01% in the fish oil group, 11.49% in the linseed oil group and 6.91% in the corn oil group(p<0.05). This result suggests that it is possible to reduce the cholesterol content or to increase the n-6 and n-3 polyunsaturated fatty acid contents in eggs by the manipulation of dietary fats.

• Food Science of Animal Resources
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• v.18 no.4
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• pp.339-347
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• 1998

The effects of conjugated linoleic acid (CLA) in egg yolk on fatty acid composition and lipid oxidation during chilled storage (4$^{\circ}C$) were investigated. CLA was synthesized according to the method of alkali isomerization using safflower seed oil (SSO). A total of 250 hens (200 days of age) were fed control diet (commercial formula feed for han) or CLA-supplemented diet (1%, 2.5% and 5% CLA) or 5% SSO supplemented diet for 6 weeks, and eggs were collected for analysis of CLA, fatty acid compositons and lipid oxidation. Eggs from CLA-supplemented diets groups showed significantly (p＜0.05) higher CLA content compared to those of control group. The contents of linoleic, palmitic, and myristic acid were increased as well as CLA content by feeding a CLA-supplemented diet. However, the contents of oleic and arachidonic acids in egg yolks were decreased by dietary CLA supplementation. The pH of egg yolk increased by the levels of CLA during storage. The contents of CLA were not significantly (p＜0.05) changed during chilled storage for 28 days, whereas TBARS were significantly (p＜0.05) increased. It is suggested that lipid oxidation of egg yolk might be affected by the levels of CLA in egg yolk due to changes in fatty acid compositions.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.3
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• pp.444-449
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• 2006

This study investigated the effects of dietary supplementation of cheese byproduct on performance, egg quality and fatty acid profile of egg yolk lipids from laying hens. One hundred five 30-wk-old White leghorn laying hens were randomly distributed into five groups of twenty one hens each and maintained in individual laying cages for 4 weeks. The hens were assigned to five treatments that consisted of corn-soybean meal based diets containing 0, 1, 3, 5 or 10% of cheese byproduct. Feed intake and rate of egg production of hens were not significantly different across the treatments during the whole experiment (p>0.05). Similarly, egg yolk cholesterol level, egg weight, Haugh's unit, eggshell thickness, color, and strength were not significantly different across the treatments (p>0.05). The amount of C16:0 in egg yolk was not significantly different across the treatments, but that of C18:0 decreased with increased cheese byproduct (p<0.01). Monounsaturated fatty acid (C16:1 and C18:1) content in egg yolk was similar across the treatments. Total CLA and cis-9, trans-11 CLA content increased linearly with increased cheese byproduct (p<0.001), while trans-10, cis-12 CLA amount was not significantly different across the treatments (p>0.05). Total saturated fatty acid (SFA) in the egg yolk was decreased as the level of cheese byproduct including CLA increased (p<0.01). However, the amount of unsaturated fatty acids (UFA) such as monounsaturated fatty acids (MUFA), n-3 polyunsaturated fatty acids (PUFA), n-6 PUFA, and total PUFAs in the egg yolk were not significantly different across the treatments (p>0.05). Therefore, the present results showed that cheese byproduct beneficially improved the fatty acid composition of concern to human health in the egg yolk without adverse effects on egg quality.

• Korean Journal of Poultry Science
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• v.21 no.3
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• pp.183-193
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• 1994

White Leghorn hens were fed a commercial formula feeds as a basal diet, which was supplemented with 3 types of plant oil safflower, evening primrose and pine seed, at the 10% level for 3 weeks. No significant changes was found between the basal diet and the oil feeding trials in the egg yolk cholesterol content, the laying rate, the egg weight, and the yolk weight, except the feed intake. In the fatty acid composition of the egg yolk lipid, however, the plant oil feedings to hens resulted in considerable increase of $C_{18:2}$ acid with a simultaneous decrease of $C_{18:2}$ acid ,and, consequently, followed by the improvement of balance with P /S and P /M /S ratio close to 1.0 and 1:1:1, which is known a desirable ratio for human health in lipid nutrition, respectively.