Assuming there is nothing terribly wrong with your tap water, use tap. Even with low level bacterial levels under a “boil water” notice from your utility you could still use tap water to boil an egg.
A boiling start for 30 seconds to a very gentle simmer for 13 minutes, then an ice bath at the end makes perfect, easy-to-peel hard-boiled eggs.
Bring your eggs to room temperature before boiling. If the eggs are too cold, the shells may crack during cooking. Place the eggs in a saucepan of cold water. Place the pan over medium heat.
If you're about to place uncooked eggs in a pot of boiling water, stop what you're doing immediately. Making hard-boiled eggs should always begin with cool water. Bringing the water and eggs up in temperature together helps promote even cooking and prevent cracking. Follow this tip: Always start with cold water.
The fresher the eggs, the harder they are to peel. This is because the egg white or “albumen” in a fresh egg has a relatively low pH level, making it acidic. When cooked, these fresh egg whites bond strongly to the inner shell's membrane.
If you don't plunge your egg into cold water when you take it off the heat, it goes on cooking . . . and cooking . . . and cooking. The longer you cook the egg, the more likely you are to end up with a rubbery white and a green yolk.
Directions. Place your eggs in a pot and cover with cold water by 1 inch. Bring to a boil over medium-high heat, then cover, remove from the heat and set aside 8 to 10 minutes. Drain, cool in ice water and peel.
Instead, heat the eggs gently using the water. This allows for a gradual, even cook that equals the perfect hard-boiled egg. You'll know that your egg is perfectly cooked if it has an opaque, yellow center. The yolk of an overcooked egg, on the other hand, will turn a greenish-gray color.
If you boil it for hours, it becomes rubbery and overcooked. Beyond that, things get a little mysterious. Eggs are full of coiled-up protein molecules. Heating the proteins makes them uncoil and link up with one another to form a three-dimensional lattice, transforming a runny raw egg into a firm, rubbery cooked egg.
Apparently super fresh eggs are difficult to peel because the pH of the white is more acidic which causes it to adhere to the shell membrane more tightly. Two solutions here – use older eggs or add a little bicarb soda to the cooking water to increase the pH.
If you're still struggling, peel the eggs under cold running water, which will help separate the shell from the egg. For a more eco-friendly solution than keeping your tap running, you can just peel the eggs in a water bath. The water will have the same effect of slipping under the shell and helping dislodge the egg.
When you plunge the eggs into a bowl of ice and water, the shock of the cold water stops the cooking process, preventing them from overcooking, explains The Spruce Eats. Otherwise, the residual heat in the eggs will continue to cook them, even after they have been removed from the source of heat.
The only problem with this approach, though, is even if you lower the eggs as gently as possible into the boiling water, they can easily crack. This is because cold eggs are shocked by the extra-hot water. To prevent this, remove your eggs from the refrigerator before you start bringing a pot of water to a boil.
It's important to start the eggs in cold water — bringing the water and eggs up in temperature together ensures even cooking and prevents cracking. Bring the water to a rolling boil over high heat, then immediately remove the pan from the heat. Cover, and let stand for 10 minutes. Carefully pour out the hot water.
For one to four eggs, bring the water to a rolling boil, cover the pot, and turn the heat down to its lowest setting for 12-14 minutes. For five to eight eggs, cook for 15 to 18 minutes. For nine to one dozen eggs, cook for 20 minutes. After cooking, transfer the eggs to a bowl of ice water.
As soon as the water comes to a boil, turn off the heat! The eggs sit for about 15 minutes to let them cook fully through.
The rapid cooling of the eggs contracts the egg whites, releasing them from the egg's membrane. It also firms the egg white proteins, making them easier to peel. Cool the eggs for at least 15 minutes for even easier peeling.
Leave the egg in the water for 24 hours. Osmosis will occur; that is, the water will migrate from the side of the membrane where water molecules are abundant (i.e. outside the egg) to the side where water molecules are less abundant (inside the egg). After 24 hours, the egg will be plump again!
You should not eat overcooked eggs. Here is why. When you boil eggs, hydrogen sulphide - a toxic gas is released in the whites of the egg. This happens especially when you overboil the eggs.
Leave the egg in the water for 24 hours. The water will migrate from the side of the membrane where water molecules are abundant (outside the egg) to the side where water molecules are less abundant. After 24 hours, the egg will be plump again.
If the egg sinks, it is fresh. If it tilts upwards or even floats, it is old. This is because as an egg ages, the small air pocket inside it grows larger as water is released and replaced by air. If the air pocket becomes large enough, the egg may float.