Not Only Chocolate and White, Chicken Eggs Can Also Be Colorful, IPB University Expert: This is the Explanation
If the colors of purebred chicken eggs that we often encounter are generally white and brown, it turns out that there are also other colored chicken eggs. Free-range chickens and other local chickens produce eggs with beige, greenish, bluish colors, and some have blotches.
Prof Ronny Rachman Noor, Ecological Genetics Expert at IPB University explained that the color of chicken eggs is largely determined by the type of chicken. This is directly related to inherited genetic factors. This means that certain types of chickens will produce eggs with certain colors as well.
For example, he explained that Barnevelders and Rhode Island Reds chickens produce brown eggs. White eggs are generally produced by Leghorns and Silky chickens.
“Free-range chickens generally produce white eggs and some have slightly cream-colored eggs,” explained Prof Ronny.
For a better understanding of how certain egg colors are produced by chickens, it is better to understand the process of egg formation. Starting from the formation of the yolk, it is released then added with egg white and finally wrapped by the eggshell in the chicken’s reproductive tract.
Prof Ronny revealed that the basic ingredients of chicken eggshells are basically the same, which are made of calcium carbonate. Furthermore, in the chicken reproductive tract after the shell is formed, this egg will be coated by various chemicals. The final coating of chemicals that occurs in the chicken’s reproductive tract called the oviduct is what will make the egg colorful.
“For example, the brown egg color is caused by the coating of a pigment on the eggshell called protoporphyrin IX. This chemical is almost similar to hemoglobin in the blood, but there are differences,” explained Prof Ronny.
“Blood hemoglobin contains iron that causes blood to be red, while protoporphyrin IX does not contain iron, so the resulting color is brown,” he continued.
Meanwhile, chicken eggs will be white if in the final process the eggs are not coated by any pigment in the chicken reproductive tract. So, this white chicken egg is only made of white calcium carbonate.
As for the bluish-colored chicken eggs, they occur if in the formation stage, the shell is coated with oocyanin pigment that absorbs into the eggshell.
“If we look closely, the bluish chicken eggshell does not only occur in the eggshell layer, but in the entire eggshell because the oocyanin pigment is absorbed evenly throughout the eggshell,” said Prof Ronny.
Then, what about greenish-colored chicken eggs? Although rarely encountered, Prof Ronny said that this can happen if we cross a breed of chicken that produces brown eggs with a breed of chicken that produces bluish eggs.
“In the process, this greenish color appears because the bluish eggshell due to the absorption of oocyanin pigment is then coated with a layer of protoporphyrin IX,” he explained.
There are also pink chicken eggs. Prof Ronny said, the pink egg color comes from the cuticle which will naturally cover the pores of the eggshell. This pink color will usually fade before the eggs are sold in the market due to touching, washing, and others.
“Perhaps some of us have also noticed chicken eggs with blotches in their color, as is common in quail eggs. This happens due to the pigmentation process of the egg,” said Prof Ronny.
In the chicken’s reproductive tract during egg production, the egg will rotate at a certain speed so that the pigmentation process occurs evenly. However, if the rotation process of the egg in the chicken’s reproductive tract occurs slower than usual, the resulting egg is a splotchy colored egg because the pigmentation does not occur evenly.
“So, if one day we are shopping for eggs and find colorful chicken eggs, then we understand why it can happen,” concluded Prof Ronny. (*/Rz) (IAAS/RUM)
