Century egg

How it works

The English names century egg, hundred-year egg, and thousand-year egg are jokes about the look of the finished egg. The Chinese name you will meet on menus is often pidan. The egg is packed with an alkaline paste or soaked in an alkaline brine. Salt, ash, slaked lime, clay, and rice husks appear in traditional packs. The alkali raises the pH so the proteins in the white and yolk denature and set without heating in a pan.

Over weeks to a few months, depending on the method and the size of the egg, the white becomes a dark, glossy gel and the yolk turns a deep green-grey with a creamy center. The smell is ammoniac and sulfurous. That aroma is expected from the chemistry, not a sign that the egg sat in a cupboard for a lifetime.

Commercial producers control the alkali, time, and temperature so the eggs can be sold at a grocery counter. Home recipes that mix strong lime or lye are chemical work, not a folk shortcut to skip care. If you are not set up to handle caustic materials, buy finished eggs from a shop that sells them as food.

How it is eaten

A century egg is already set. You peel it, rinse off any coating, and slice it. It is served cold or at room temperature more often than it is fried as a breakfast egg. Common plates pair it with silken tofu, scallion, and soy; fold it into congee; or chop it into a cold salad with ginger. Some cooks add a little fresh egg around it in a steamed dish so the two textures sit side by side.

Peel and rinse before slicing. Serve with mild foods: tofu, rice porridge, plain rice. Add fresh aromatics such as ginger, scallion, or coriander if you want contrast. Keep refrigerated after opening the pack, as you would other preserved eggs.

The flavor is salty, mineral, and rich rather than “eggy” in the fried-egg sense. People who like it usually like that contrast. People who do not are often reacting to the smell before the first bite. Cutting the egg and letting it air for a minute on the plate is a practical step, not a ritual. The name promises a century; the jar only has to wait weeks.

What it is not

It is not a rotten egg left out to spoil, and it is not an ordinary hard-boiled egg dyed dark. Spoilage is bacterial breakdown. This process is a controlled alkaline cure. A hard-boiled egg is cooked with heat; the white stays pale. If a peeled egg is slimy in the wrong way, unevenly putrid, or from a damaged shell you cannot trust, do not eat it. That is ordinary food caution, the same as with any preserved product.

It is also not a dessert and not a year-count of age. You will not find a vintage on the shell that records a hundred years. The “century” is a nickname. When a recipe says to use one century egg, it means one preserved egg of this type, not a century of curing time in your kitchen.

Buy eggs sold for eating, not a craft experiment with unmarked chemicals. Check the pack date and the integrity of the shells. Peel, rinse, and slice just before serving. Refrigerate leftovers and finish them promptly.

If you are cooking for someone new to the ingredient, serve a thin slice with rice or tofu rather than a whole egg as a first plate. The food is rich. A small amount is how most tables use it.