The confusing magic of peeling hard-boiled eggs
Ages ago I had a dispute with a friend over peeling hard-boiled eggs. She swore by her mother’s wisdom that the freshest eggs were the easiest to peel. I swore by my grandmother’s wisdom that cold water does the trick. The debate was heated and emotional, probably due to our investment in our maternal relatives’ kitchen knowledge. Food and family, as we know, is a potent combination.
So, I was boiling eggs this morning, and they came out sort of eh. I recalled my disagreement and decided to turn to the eggsperts (lame pun, I know).
First, “hard-boiled egg” is a misnomer according to IncredibleEgg.org. I think it’s because you’re not supposed to actually boil the egg. The proper name is “hard cooked.”
Everything behind what makes an egg peelable is scientifically explained on a couple of websites (Khymos, a molecular gastronomist’s blog, and the University of Exeter’s School of Physics website). I did not understand either of the sites, so I turned to other people’s kitchen wisdom. The information is generally conflicting but there are some consistencies.
First up, salt. Some do use it, some don’t. It either helps prevent the egg from cracking or it raises the boiling point of water and makes the eggs rubbery.
Then, there’s vinegar. I haven’t seen anyone say don’t use vinegar. Some say that it keeps egg whites from running out of any cracks. According to Chow.com’s source, Juan Silva, a professor of food science and technology, vinegar softens and dissolves the eggshell because the shell is made of calcium carbonate.
I’ve never heard of using baking soda. Again, no one says don’t use it. Those who do use it say that it raises the pH which breaks down the protein that holds the egg inside of the shell so that the egg does not adhere to the shell.
On to my friend’s argument: Freshness. Pretty much everyone who refers to age of the egg says that you don’t want to use fresh eggs. One site simply stated that you needed the membrane to “mature.” I’m not entirely sure what this means. Another website says that age breaks down the albumen or protein. FineCooking.com has an interesting and scientific if humorous sounding explanation: Eggs were meant to be chickens. The older an egg is, the more it wants its shell to crack because it wants to be a chicken. There’s a chemical process in the aging that makes a shell more vulnerable.
Water temperature before, during, and after cooking seems to be crucial.
1. Before cooking: use cool/lukewarm water, OR eggs and water must both be at the same temperature, OR bring eggs to room temperature before cooking (to prevent cracking and reduce cooking time). I suppose you could use cool/lukewarm water and cool/lukewarm eggs in a cool/lukewarm room. That way you cover all the bases.
2. During cooking – here’s where things get dicey!
There is conflicting information on whether or not to bring the water to a full boil. Our food science professor is one who says yes. Tim Ferriss say to slow-boil the eggs for twelve minutes. Some say that you need to remove the pot once the water hits a boil, then cover the eggs, and let them continue to cook in the heat held in the hot water. According to FineCooking.com, boiling the eggs causes bubbles beneath the shell that makes the shell crack. They want you to bring the water to 170-180 degrees for ten minutes in order to get the egg center to 165 degrees. *blink* There’s nowhere to stick a thermometer to get the inside temperature. Those who follow this method of removing the eggs from the stove and letting them stew in the residual heat say that timing must be precise, but the time they suggest varies. The range is 15-20 minutes.
One site claimed that this method is called “coddling.” I’m not sure this is accurate. You can look it up for yourself and decide.
3. After cooking – nearly everyone agrees! Icy cold water! Explanations vary:
* It helps the membrane stick to the shell instead of the egg.
* Steam develops between the egg and the shell.
* From our food science professor, it makes the inside of the egg shrink faster than the shell. The shell is less prone to expansion and contraction. So the egg doesn’t adhere to the shell. You have to be quick before the egg starts to expand again.
Finally! The peeling!
Folks are pretty consistent about this point. The options are tap the large end, then the small end, roll, and peel. There is one silly alternative, which is to blow the egg out of its shell. Yes, seriously, blow. This is according to the blog of “Lifestyle Experimenter” Tim Ferriss (you guessed it, a lifestyle coach). Check this guy out. Seriously. Look what we’ve come to. Behold and be fearful. I think it’s hysterical that he’s blowing an egg.
Alright, so here’s the interesting part. The folks at Incredible Egg say do use salt. Use eggs you’ve had for a week. Use ice water, then peel.
But wait! Things get even more interesting.
According to Wired.com, eggs are getting harder and harder to peel. According to the article, production time has gotten faster, so eggs get to the supermarket faster, making them even more fresh than before, and therefore harder to peel. This article goes into more scientific detail about why “not so fresh” eggs are easier to peel. This article also confirms the baking soda method.
Last, some humor!
Steve Bass over at PCWorld shows us two wonderful sites. The first is for a high-tech egg peeler, the Eggstractor. The other is for Eggpeeling.com, a funny site with videos of the bizarre ways people peel eggs (ex: with a chainsaw).
In sum, I feel very confirmed and validated after all these years. I will not try to measure the temperature of the water or the center of my eggs. I will probably do what I always do, which is toss the eggs in a pot and let them boil while I go do something, and go back to them when I remember or when I smell the burnt egg smell. Still, it’s nice to know my grandmother was right.
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