Eggs are a rich source of proteins. Unfortunately, they are the same reason why hard-boiled eggs are sometimes frustrating to peel. It might be challenging to remove the shell without breaking the egg when this membrane adheres to the egg white. The ease with which an egg can be peeled is determined by a number of factors. And these include the age of the egg, cooking method, and how the egg is chilled after cooking.
While hard-boiled eggs might be tough to peel at times, there are steps you can do to increase your chances of getting a clean peel. With the correct method, peeling boiled eggs can easily be done. But before that, let’s see how hard-boiled eggs adhere to the inner surface of the shell.
WHY ARE SHELLS OF HARD-BOILED EGGS HARD TO PEEL?
There are two thin membranes that separate the egg white from the shell. First is the inner membrane that encloses the egg white or albumen. And the other is the outer membrane that coats the inside of the shell. The egg white, also known as albumen, is composed of water and proteins kept together by weak hydrogen bonds. The structure, as a whole, is held together by a protein matrix that also contains phosphorus and magnesium in trace amounts.
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During boiling, the heat makes the proteins in the membranes unravel in a processed called denaturation. And as they cool, they cling together to form a solid mass that adheres to the inner surface of the shell. This is what makes the egg shell of hard-boiled eggs hard to peel. This is especially true for fresh eggs.
pH level of eggs
The pH (acidity) of fresh egg white is close to neutral. Their pH can be as low as 7.6, according to the American Egg Board. When cooked, whites with this low a pH strongly adhere to the membrane of the inner surface of the shell. However, the acidity of eggs decreases with age —it can reach a pH of 9.2. The reason for this is the carbon dioxide gas that gradually escapes through the pores of the shell. If the egg white is less acidic, the link between the white and the inner membrane is weaker. The result? Peeling hard-boiled eggs is much easier.
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With that being said, you would want to opt for older eggs. For the best results, choose eggs that are at least a week old or two. To determine the age of eggs, gently set them in a bowl of water. They are fresh if they sink to the bottom and lie flat. If they stand up or float, they are older and easier to peel once boiled. For more methods that determine the freshness of eggs, this article should help.
WHAT ELSE YOU CAN DO?
Aside from boiling only eggs that are at least 1-week old, another thing that you can do is “shocking” the hard-boiled eggs. When we are in a hot environment and then to a cold area suddenly, our body becomes under stress as it adjusts to the temperature change. And afterwards, we would experience discomforts such as cold and sneezing. Shocking the eggs is similar to this. To do this, right after boiling, simply allow the eggs to sit in ice-cold water for about 5 minutes.
Shocking the egg in ice-cold water (cool water is not cold enough) hardens up the membrane proteins and causes the egg white to shrink back from the shell. After shocking the eggs, peeling the shell should be a breeze.
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To remove the shell, gently tap the egg on a firm surface. The countertop or a chopping board would do. Tap it all around to make small cracks all around the egg. Do not tap too hard or you will break the egg within. Start peeling from the broader end of the egg, where the air pocket is located, once the shell has been broken. The shell should readily peel off in huge chunks. If you are having difficulty peeling the egg, try running it under cold water while you peel to help loosen the shell. The water will also aid in the removal of any small fragments of shell that may have been stuck to the egg. This method comes in handy when you need to peel a big number of eggs at once.
Another way to remove the shell is by rolling the egg between your hands to loosen it.
