On so-called “hard-boiled” eggs
Phnom Penh; March 27, 2021:
Passover begins today and ends on Easter Sunday. So called “hard-boiled” eggs are central to both religious celebrations.
All of us have had trouble perfectly boiling eggs at one time or another. Even the experts such as Harold McGee, who writes about the chemistry of food, admits that there is no surefire method to ensure that the shells won’t crack, the yolks don’t turn grayish-green, and the inner membranes between the shell and the whites peel away easily. His seminal “On Food and Cooking: The Science and Lore of the Kitchen” was initially published in 1984 and revised in 2004. It was one of the best-selling books in my culinary bookstore in the 80s and 90s.
But never mind the pitfalls: there are some basics of food science that will help you cook eggs that peel more easily. If you have kids in your life and are simply going to dye a bunch of eggs and leave them hidden outdoors, you probably won’t be eating them anyway – though cooked eggs actually keep well in the shell. But if you want to have Easter eggs and eat them too, then I have several suggestions based mostly on personal experience.
Foremost, use old eggs. If you have not yet purchased your eggs, buy them now. The air pocket on the large end of an egg grows larger as the egg ages. The pocket provides you with a starting point to begin peeling. It also gives you a space to slip your thumbnail up under the membrane between the shell and the white.
The eggs should be at room temperature. Some experts advise placing the eggs in a pot of warm water to begin.
McGee adds his eggs to boiling water, then turns the heat down to very low and cooks them for 10 minutes. Eggs coagulate at 145°F (63°C); if boiled, the whites will be rubbery. No matter how you cook them, you should transfer them to an ice bath to stop the cooking. They should be cooled when you begin to peel them.
I cooked eggs several different ways this week. My tried-and-true method had the best results: Add a teaspoon or so of baking soda to the pot you are going to cook them in. Add warm tap water and stir around to dissolve the soda. Add the eggs. (Do not stack the eggs as that causes cracking. Use bigger pots or several at once.) Add more water if necessary to be sure that they are covered. Turn on high heat and bring almost to a boil. Control the heat so that it simmers… Do not let it boil furiously or you will end up with rubbery whites and yolks that are grayish green on the outside. Let them steep (a bare simmer, not a boil) about 9 minutes. Of course, the timing depends on the age and size of the eggs, but 9 minutes works well to cook the average eggs we get here in Cambodia so that they have firm yolks. (That said, the eggs here are generally smaller.) If you pick one up and spin it around, it should spin around without wobbling. (A second method I tried with decent results was to bring the water to a boil, then turn it down and allow the eggs to steep 5 to 9 minutes or from 12-13 if you want thoroughly dry yolks for grating. But I don’t like letting the water boil for reasons explained below.) When they have finished simmering, pour the hot water off, and place them in an ice water bath. Let them thoroughly cool. To shell them, start at the fat end and there should be a gap of air where you can begin… I sorta crack the shell all around and I peel them under a thin stream of running cool water. If the eggs are a week or two old, it is much easier to peel because not only will there be that gap of space but also there is a thin membrane between the shell and the white that is easier to remove the older the egg is. There are actually two of these membranes, which are a protein that protects the egg from bacteria. Scientists, chefs, and so-called molecular gastronomists all agree that there is no absolute way to avoid the membrane, but starting them in hot water seems to help. Also, the alkaline solution provided by the bicarbonate of soda weakens the binding of the inner two membranes. (Fresh eggs are acidic but they become more alkaline as they age. Older, alkaline eggs are easier to peel.)
The longer and hotter eggs cook, the more the hydrogen sulfide in the whites reacts with the iron in the yolks to create ferrous oxide, turning the yolks that ugly gray-green and producing the odor of sulfur. Paradoxically, egg yolks also contain anthocyanin pigment molecules which are also found in blueberries and red cabbage. Sensitive to alkaline pH, anthocyanins can easily go from reds to green when heated in an alkaline solution. If your blueberry muffin recipe contains baking soda or baking powder, you may have seen your muffins turn a nightmarish color! Nevertheless, I highly recommend adding the baking soda to the water for easy peeling and never letting your “hard-boiled eggs” boil!