Egg yolk coloring experiment


How do you consider the color of egg yolk?

The color of egg yolk sold by merchants has many kinds from light-colored (looking white) to dark-colored (closing to red). Different people have different opinions. Some people prefer dark colors; while others prefer light colors. As a consumer, which kind do you prefer? According to my company’s investigation, most of the consumers consider that the darker the color of egg yolk is, the more delicious it is and the higher the nutrition value is. However, is that true? What is your opinion?

Generally speaking, people in European and American countries prefer light-colored egg yolk. However in Japan, dark-colored egg yolk is more popular. In America, the egg yolk used in experiment belongs to light-colored egg yolk.

Does the different color of egg yolk have deeper implications, such as nutrition value, taste and so on? How does it result in the differences of color of egg yolk? My company keeps thinking in practice, and hope that the questions above can be solved through this experiment.

Research method

   We must know little about the method of adding pigment to change the color of egg yolk when raising poultry. So let’s prove the method by experiment. First, you should prepare for work. Red pigment and black pigment are prepared to add. The output of eggs are collected after adding edible food color feed, and the changes of color of egg yolk are observed after boiled eggs. Pigment used in this experiment is powdered pigment. Red pigment is “paprika pigment”, while black pigment is “Sudan black B pigment”. Incidentally, Sudan black B pigment is not food coloring, but staining pigment used in the experiment.

Experiment 1-1
Adding 0.1 percent of black pigment (Sudan black B pigment) to feed, and keeping raising it every day uninterruptedly.
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Experiment 1-2
Adding 0.1 percent of black pigment (Sudan black B pigment) to feed one day, and raising it two days without adding pigment feed. And keep raising it in this way.
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Experiment 1-3
Adding 0.5 percent of red pigment (paprika pigment) to feed, and keeping raising it every day uninterruptedly.
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Experiment 2-1
After conducting the experiment 1-1 for about 20 days, keep raising it without adding pigment feed.
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Experiment 2-2
After conducting the experiment 1-2 for about 20 days, keep raising it without adding pigment feed.
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Experiment 2-3
After conducting the experiment 1-3 for about 20 days, keep raising it without adding pigment feed.
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Experiment preparation
Pigments used in the experiment


Sudan black B pigment

 red paprika pigment used in feed

Experiment subjects

Chicken poultry species  Julia (white jade)
Number                 6
(3 experiments, 2 for each experiment)

Experiment results
Because experiment subjects do not necessarily produce one egg every day, there will be no record sometimes. Experiment results are as follows:


experiment 1-1、 2-1

blue merle

  experiment 1-2、 2-2


  experiment 1-3、 2-3



Experiment 1
















  Experiment 2















Shape of raw eggs

Egg yolk without adding pigment

Experiment 1-1:

the 15th day after adding black pigment

Experiment 1-3:

the 15th day after adding red pigment

Experiment 2-1:

the 15th day after stopping adding black pigment

Comparisons of color of egg shell

The first line from the inside belongs to eggs without adding pigment.

The second line belongs to eggs adding black pigment.

The leftmost is the first day of egg after adding pigment, while the rightmost is the fifth day of egg after adding pigment.
In accordance with the imagination, the pigment in the feed will change the color of egg yolk.

In the experiment 1-3, because paprika pigment is added little, it is difficult to judge the differences of color from the picture. But according to naked eye, it is inferred that egg yolk has a light color.

In the experiment 2-1, pigment decolorization exists. Although there is no complete decolorization, the color has changed into light green. The color of chicken is changed into black after stopping adding black pigment, so it is predicted that pigment still exists inside the chicken body.

Experiment 2-2 has a lighter color than experiment 2-1. However, the same conclusion can also be reached.

No comparison experiment on squid ink black pigment is carried out this time. But our company has carried out this experiment before; finding out that egg yolk is not colored. By comparing the differences between Sudan black B pigment and squid ink black pigment, we can see that Sudan black B pigment is fat-soluble pigment, and that squid ink black pigment is water-soluble pigment. Water-soluble pigment is excreted from the body. It does not remain in the chicken body, so it does not change the color of egg yolk. Although there is no picture, the chicken after raising Sudan black B pigment feed has changed into black completely. It is confirmed from the result of experiment 2 that pigment inside the chicken’s body will influence color of egg yolk. It is also confirmed that from the changes of color of egg shell that pigment inside the chicken body will not only influence color of egg yolk, but also make the color of egg shell dark.

So, how does the egg inside chicken’s body produce? Egg maturation needs about 8 to 9 days. First, the egg yolk part is formed. Then protein will wrap egg yolk. Next egg shell membrane and egg shell has grown up, which is excreted from the chicken’s body. It is observed from the experiment that egg yolk forms from the outside to the inside. The complete coloring of egg yolk needs 10 days.

Industry insiders believe that the differences of the colors of egg shell and egg yolk cannot change the egg’s nutrition value. But this experiment only makes coloring experiment on research subjects, and this conclusion is not proved. In order to make analyses about nutrition value, it must be sent to related inspection department. In the future, our company will catch the chance to make comparative study on nutrition value subjects.

If you feel interested in this experiment and the products, please contact my company.