|
|
I have been trying to make salted eggs and have discovered the following facts:
-
I soaked some raw eggs in salt water (1%, 3%, 7% and saturated salt water) for two and a half days.
Then I tasted the saltiness of each egg after having boiled them in the original salt water.
None of them were salty. However, when I left the eggs in the saturated salt water for 24 hours after having boiled them, the entire eggs, including egg white and egg yoke, became salty.
-
I soaked some raw eggs in vinegar for 5 hours then transferred them into saturated salt water and left them there for two and a half days.
Then I tasted the eggs after having boiled them in the same salt water. The egg white was slightly salty and the egg yoke had a bit of saltiness but not as much as the egg white.
Are these results due to the changes in the permeability of the eggshells and/or the shell membranes?
Have the eggshells and/or shell membranes changed from semi-permeable to permeable and let the sodium chloride into the eggs?
K.T.
(Mar 2003)
|
|
|
| |
Answer:
Dr.
Yukinori Yoshimura, who is an expert of the reproductive systems of birds, kindly answered the above questions.
Your observation and speculation seem to be accurate and correct.
I will give you some brief answers to your questions first, and then I will explain in detail.
-
The first experiment
Eggshells become more permeable when they are boiled. When the eggshells become more permeable, they can let some substances such as salt enter into the eggs.
Therefore, the eggs became salty when they were soaked in the salt water after being boiled.
-
The second experiment
Some physical changes occurred in the eggshells and the shell membranes when the eggs were placed in the vinegar for 5 hours.
However, the eggs did not become as salty as the ones in the previous experiment.
Since the vinegar makes the eggshell release some of its calcium ions into the vinegar solution and coagulates the protein, vinegar seems to enhance the permeability of the eggshell.
But, the vinegar did not seem to affect the permeability as much as the heat in the previous experiment.
I also think that these eggs didn’t become as salty as the previous ones because they weren’t soaked long enough in the salt water after being boiled.
An egg consists of the egg yoke that is enclosed in the yoke membrane, thick and watery egg white enclosed by the shell membrane, and the eggshell.
The eggshell is made mainly of calcium carbonate and also contains traces of a few inorganic and organic substances.
It has many small pores for the embryo in the egg to respire when it matures.
The eggshell is covered with the cuticle, which also covers the pores in some degree, to prevent germs from going inside the egg.
The cuticle will be removed when the egg is washed by water, which causes the egg to spoil more quickly.
The shell membrane is made of the substances such as collagen, and has reticular structures.
The reticulum is sealed by proteins.
When an egg is boiled, the cuticle is removed from the shell, and the protein coagulates and transforms into a coarse structure.
These changes seem to make the eggshell, shell membrane, and the egg white more permeable.
When the eggs are placed in the vinegar, the eggshell becomes more permeable because calcium in the eggshell is released in the vinegar and the protein coagulates.
However, it is difficult to say that soaking in the vinegar for 5 hours is long enough to change the permeability of the eggshell.
Finally, let me give you a short talk related to this article. When part of a fertilized egg is briefly soaked in alcohol that includes pseudo-female hormones (endocrine-disrupting chemicals), the born bird has reproductive abnormalities.
This indicates that endocrine-disrupting chemicals can go inside the egg from the surface.
Acknowledgment
Dr. Yukinori Yoshimura
He is studying the reproductive function of birds and the effect of endocrine-disrupting chemicals on birds.
Please look at his website for details.
*This article is translated by Chemistryquestion.com from the original article in Chemistryquestion.jp. Please let us know if you find any errors.
|
|
