Why Do Shells Stick to Boiled Eggs?
Hard-boiled, fresh eggs (eggs less than two weeks old) are difficult to peel because the white of the fresh egg adheres to the shell's inner membrane, according to EDinformatics. Over time, the chemistry of the egg is altered and becomes easier to peel. Working with eggs that are 10 to 14 days old can take the frustration out of the peeling process. Does this Spark an idea?
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Acidity Level
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EDinformatics explains that the white of a fresh egg has a high acidity level because of the presence of carbon dioxide. Over the course of two weeks, the shell becomes porous, allowing carbon dioxide to seep into the egg, lowering the acidity level. At lower acidity levels, the inner membrane of the shell does not adhere as well to the white of the egg making it easier to peel.
The Shrinking Egg
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Another change that happens to a fresh egg over time, according to EDinformatics, is that the egg white and yolk will shrink. This increases the air space between the egg shell and the membrane, allowing a boiled egg white to release more easily from the membrane.
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Time Frame
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The best egg for boiling is 10 to 14 days old, according to Chef David Nelson, a certified cooking instructor and founder of Chef2Chef.net. To determine the age of the egg, Nelson says to look to the United States Department of Agriculture, or USDA "Pack Date." This is a three-digit number that represents consecutive days of the year. For example, Jan. 1 is 001 and Dec. 31 is 365. This number is often found on the short end of the outside of the carton next to the "Use by Date."
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References
- Photo Credit the way of the egg. image by bluefern from Fotolia.com
