I
was going to scramble and when I cracked one egg the yolk was yellow only to
crack open the other egg and found an entirely white yolk.
I've
been used to seeing both white and yellow yolk. I still remember when I was young
I asked my mum the reason for this and the explanation she gave was that if you
feed chickens with white corns/maize there's the possibility of having a white
yolk and so is the case of feeding it with yellow corn/maize there's the
possibility of having a yellow yolk, So I decided to do a thorough research on
what really influences the egg yolk of a chicken.
Definition of Egg yolk from Wikipedia:
An
egg yolk is a part of an egg
which feeds the developing embryo.
The egg yolk is suspended in the egg white (known alternatively as albumen or glair/glaire)
by one or two spiral bands of tissue called the chalazae. Prior to
fertilization, the yolk together with the germinal disc is a single cell, one
of the few single cells that can be seen by the naked eye.
As
a food, yolks are a major source of vitamins and minerals. They contain all of
the egg's fat and cholesterol, and about one-half of the protein. If left
intact while cooking fried eggs, the yellow yolk surrounded by a flat blob of
whites creates a distinctive sunny-side up form. Mixing the two components
together before frying results in a pale yellow mass, as in omelettes and
scrambled eggs.
Bellow was my findings.
The
colour of the yolk is due to substances called carotenoids.
The most
important sources of carotenoids in poultry feed are maize (corn), maize
gluten, alfalfa (lucerne) and grass meals; these sources contain the pigmenting
carotenoids lutein and zeaxanthin, which, together with other oxygen-containing
carotenoids, are known by the collective name of xanthophylls.
However, the carotenoid content in the
ingredients of poultry feed is not constant; the pigmentation properties of the
carotenoids can be weakened or lost in a variety of ways. These fluctuations in
carotenoid content and availability concern both the poultry nutritionist and
the feed producer. Because of such fluctuations, naturally-occurring
carotenoids cannot be relied upon to provide the desired yolk colour or to
provide a consistent colour. Therefore, nature-identical yellow and red
carotenoids, such as apoester and canthaxanthin, are commonly added to feed in
order to achieve the desired egg yolk colour. Consumed by the laying hen, these
supplemental carotenoids are readily transferred to the blood and then
deposited in the yolk to provide pigmentation.
I am trying to see reason with my mum’s
reasons of egg yolk being white or yellow, Since the colour of the yolk is due
to substances called carotenoids and the most important sources of carotenoids
in poultry feed are maize (corn) then if you are feeding your chickens with
white maize (corn) the eggs will have a high probability of having white yolk
and so is the case of feeding it with yellow maize (corn) there's the
possibility of having a yellow yolk.
Please Note: The nutritional value of
the egg is not affected by the yolk colour.
The color of an egg yolk is directly
influenced by the quality of the chicken feed. Egg Yolk color is generally
improved with a higher quality feed and vice-versa. Although much emphasis is
put onto the color of the egg yolk, it is not indicative of an egg's
nutritional value. The yellow color is due to lutein and zeaxanthin, which are
yellow or orange carotenoids known as xanthophylls.
Some Uses of Egg Yolk:
It is sometimes
separated from the egg whites and used in cooking (for mayonnaise, custard,
hollandaise sauce, crème brûlée, avgolemono, and ovos moles).
It is used in
painting as a component of traditional egg-tempera.
Egg yolk can be
used to make liqueurs such as Advocaat or eggnog.
Egg yolks are
used to extract egg oil which has various cosmetic, nutritional and medicinal
uses.
The developing
embryo inside the egg uses the yolk as sustenance.
Composition
of chicken egg yolk
The yolk makes up about 33% of the
liquid weight of the egg; it contains approximately 60 calories, three times
the caloric content of the egg white.
The yolk of one large egg (50 g total,
17 g yolk) contains approximately: 2.7 g protein, 210 mg cholesterol, 0.61 g
carbohydrates, and 4.51 g total fat. (USDA National Nutrient Database)
All of the fat-soluble vitamins (A, D,
E, and K) are found in the egg yolk. Egg yolk is one of the few foods naturally
containing vitamin D.
The composition (by weight) of the
most prevalent fatty acids in egg yolk is typically as follows:
• Unsaturated
fatty acids:
Oleic
acid, 47%
Linoleic
acid, 16%
Palmitoleic
acid, 5%
Linolenic
acid, 2%
• Saturated
fatty acids:
Palmitic
acid, 23%
Stearic
acid, 4%
Myristic
acid, 1%
Egg yolk is a source of lecithin as
well as egg oil for cosmetic and pharmaceutical applications. Based on weight,
egg yolk contains about 9% lecithin.
Yolk
proteins
The different yolk proteins have
distinct roles. Phosvitins are important in sequestering calcium, iron and
other cations for the developing embryo. Phosvitins are one of the most
phosphorylated (10%) proteins in nature, the high concentration of phosphate
groups providing efficient metal-binding sites in clusters. Lipovitellins
are involved in lipid and metal storage, and contain a heterogeneous mixture of
about 16% (w/w) noncovalently bound lipid, most being phospholipid.
Lipovitellin-1 contains two chains, LV1N and LV1C.
A lot of us love to eat eggs for
breakfast, especially after finding they could help with weight loss. You may
be throwing away the yolks to cut calories and reduce cholesterol, which is
fine but did you know that most of an egg's nutrients are found in the yolk?
Take a look at the comparison below to see what you may be missing.
Want to see how an egg white and yolk
compare head-to-head? Then read more
|
Egg
White
|
Egg
Yolk
|
Calories
|
17
|
59
|
Fat (g)
|
.06
|
4.51
|
Saturated Fat (g)
|
0
|
1.6
|
Carbs (g)
|
.24
|
.61
|
Protein (g)
|
3.6
|
2.7
|
Cholesterol (mg)
|
0
|
210
|
|
|
55
|
8
|
|
|
2.3
|
21.9
|
|
|
0
|
18
|
|
|
1.3
|
24.8
|
Moral
of the story: Think about keeping (and eating) a
few yolks every once in a while -- If you don't currently have cholesterol
problems, you can eat up to seven yolks a week. You can get even more detailed
info, such as how much Methionine are in a white and yolk, at the USDA Nutrient
Database.
Fit's
Tip: If you are spending extra dough on Omega-3
eggs, then be sure to eat the yolks because that is where the Omega-3s are
found.
Yeah! From the information I have
you’ll be fine eating it. The colour has no effect on the taste. Enjoy!!!