Boiled egg

Hard-boiled eggs

Hard-boiled or hard-cooked^[6] eggs are boiled long enough for the yolk to solidify (about 10 minutes).^[7] They can be eaten warm or cold. Hard-boiled eggs are the basis for many dishes, such as egg salad, cobb salad and Scotch eggs, and may be further prepared as deviled eggs.

There are several techniques for hard-boiling an egg.^[8] One method is to bring water to a boil and cook for ten minutes.^[9] Another method is to bring the water to a boil, but then remove the pan from the heat and allow eggs to cook in the gradually cooling water.^[7] Over-cooking eggs will typically result in a thin green iron(II) sulfide coating on the yolk,^[10] though the coating has been reported as having little effect on flavor.^[5] This reaction occurs more rapidly in older eggs as the whites are more alkaline.^[11] Rinsing^[3] or immersing the egg in cold water after boiling is a common method of halting the cooking process to prevent this effect,^[4] and in commercial operations the discoloration is removed by immersing peeled eggs in a bath of organic acid after cooking.^[12]

Hard-boiled eggs are recommended by the United States Department of Agricultural Food Safety and Inspection Service to be used within two hours if kept at room temperature, or within a week if kept refrigerated and in the shell.^[13][14][15] Shelled hard-boiled eggs sold in bulk are pickled or sealed in an atmosphere of carbon dioxide and nitrogen for preservation.^[1]

Hard-boiled eggs are commonly sliced, particularly for use in sandwiches. For this purpose specialized egg slicers exist, to ease slicing and yield even slices. For consistent slice sizes in food service, several eggs may have their yolk and white separated and poured into a cylindrical mold for stepwise hard-boiling, to produce what is known as a "long egg" or an "egg loaf". Commercial long eggs are produced in Denmark by its inventor Danæg [da] and in Japan by KENKO Mayonnaise [ja]. The machine for producing long eggs was first introduced in 1974.^[16] In addition to being sliced, long eggs can also be used in their entirety in gala pies.^[17]

Haminados, braised eggs slowly cooked overnight, is a traditional Sephardic Jewish dish first documented in medieval Spain and now part of Israeli cuisine, where they are typically served on their own or as part of the Shabbat stew chamin and other dishes.^[18][19]

Soft-boiled eggs

While the traditional egg timer counts to 3 minutes for cooking a soft-boiled egg,^[20] some how-to guides recommend longer cooking times ranging from five^[7] to six minutes.^[21] Chef Heston Blumenthal, after "relentless trials", published a recipe for "the perfect boiled egg", suggesting cooking the egg in water that starts cold and covers the egg by no more than a millimeter, removing the pan from the heat as soon as the water starts to bubble. After six minutes, the egg will be ready.^[22]

Soft-boiled eggs are not recommended by the Food and Drug Administration for people who may be susceptible to salmonella, such as very young children, the elderly, and those with weakened immune systems.^[23] To avoid the issue of salmonella, eggs can be pasteurised in shell at 57 °C for an hour and 15 minutes. The eggs can then be soft-boiled as normal.^[24]

Soft-boiled eggs are commonly served in egg cups, where the top of the egg is cut off with a knife, spoon, spring-loaded egg topper, or egg scissors, using an egg spoon to scoop the egg out. Other methods include breaking the eggshell by tapping gently around the top of the shell with a spoon.^[25] Soft-boiled eggs can be eaten with toast cut into strips, which are then dipped into the runny yolk. In the United Kingdom and Australia, these strips of toast are known as "soldiers".^[26]

In Southeast Asia, a variation of soft-boiled eggs known as half-boiled eggs are commonly eaten for breakfast.^[27][28] The major difference is that, instead of the egg being served in an egg cup, it is cracked into a bowl to which dark or light soy sauce or pepper are added. The egg is also cooked for 7 minutes, resulting in a runnier egg instead of the usual gelatin state and is commonly eaten with kaya toast and kopi.^[29][30]

Boiled eggs are also an ingredient in various Philippine dishes, such as embutido^[31] and chicken galantina.^[32] Boiled or steamed duck eggs that have been incubated for several days are also eaten in the Philippines, Vietnam, Laos, Cambodia, and Thailand as the food known as balut.^[33]

In Japan, marinated soft-boiled eggs (味付け玉子, ajitsuke tamago) are commonly served alongside ramen. The eggs are typically steeped in a mixture of soy sauce, mirin, and water after being boiled and peeled. This provides the egg a brownish color that would otherwise be absent from boiling and peeling the eggs alone. Once the eggs have finished steeping, they are usually served on top of the soup.^[34][35] A similar method of cooking soft-boiled eggs popular in Japan is that of the hot spring boiled egg (温泉玉子, onsen tamago), which is cooked at a constant temperature of 70 °C (158 °F) as is present in the volcanic hot springs of Japan, producing an egg with solid yolk and sol-like white.^[1]

Other variations

Piercing

Some pierce the shell beforehand with an egg piercer to prevent cracking, following recommendations first published by the Poultry and Egg National Board in 1966.^[36] The American Egg Board currently recommends against this, as it can introduce bacteria and create hairline cracks in the shell through which bacteria can enter the egg.^{[note 1]} A 1975 study showed increased cracking in pierced eggs compared to unpierced eggs.^[37]

Steaming

Eggs can be taken straight from the refrigerator and placed in the steamer at full steam.^[38]

Sous vide

Boiled eggs can be made by cooking/coddling in their shell "sous vide" in hot water at steady temperatures anywhere from 60 to 85 °C (140 to 185 °F). The outer egg white cooks at 75 °C (167 °F) and the yolk and the rest of the white sets from 60 to 65 °C (140 to 149 °F).^[39][40]

Baked eggs

Eggs may be cooked to produce a result similar to boiling via baking in an oven by breaking eggs into a muffin tin or individual ramekins.^[41]

Salted eggs

In China, eggs (particularly duck eggs) may be preserved by packing them in salt and charcoal or brine. The salted egg is then boiled or steamed prior to consumption. The process is related to century eggs, which are preserved for a long period and are not boiled.^[42] The salting or pickling process in a typical salted egg takes 20—50 days.^[1]