Century eggs explained: the preserved egg that scares everyone first
Century eggs, also called thousand-year eggs or pidan, are duck eggs preserved in a paste of clay, ash, salt, quicklime, and rice hulls for several weeks to a few months. The process raises the pH of the egg until the whites turn a translucent amber jelly and the yolk becomes dark green, creamy, and faintly ammoniac. They look alien, smell strange, and taste like nothing else: rich, savory, slightly sulfurous, with a custard-like yolk that melts on the tongue. Every Western traveler I have watched meet one has made the same face, and roughly half come back for more. I became a convert at a Changsha breakfast stall in 2017, over a bowl of rice porridge with chopped century egg and pork.
This guide explains how they are made, what they actually taste like, the chemistry behind the colors, and how to order them without regret.
Quick facts
- Despite the name, century eggs are cured for weeks or months, not a century; the name is marketing
- Duck eggs are standard because their larger whites give a better jelly texture than chicken eggs
- The curing paste uses alkali (quicklime or wood ash lye), salt, clay, and rice hulls; some commercial producers use a liquid lye soak instead
- The white turns amber-brown and gelatinous; the yolk turns dark green and creamy through the Maillard reaction under alkaline conditions
- Century eggs are eaten cooked-adjacent: over congee, with tofu, in cold salads, never scrambled like fresh eggs
- A single egg costs 2 to 5 yuan in China; imported ones in Western Chinatowns run 2 to 4 US dollars each
- Some producers still use lead oxide in the paste for faster curing; buy from reputable brands, since lead contamination is a real risk with unregulated producers
How century eggs are made
The traditional method coats fresh duck eggs in a thick paste of clay, wood ash, salt, calcium oxide (quicklime), and water, then rolls them in rice hulls and buries them in a crock for several weeks. The alkali slowly penetrates the shell, which is porous, and raises the pH of the egg from about 9 to 12 or higher. At that pH, the proteins in the white break down into a gel, and the fats and sugars in the yolk react into the dark pigments and creamy texture.
Modern commercial production often skips the paste and soaks the eggs in a lye solution for about two weeks, then ages them in plastic. It is faster and more consistent, and connoisseurs say the paste method gives a better flavor because it is slower and less harsh. Either way, the finished egg is stable at room temperature for weeks, which was the entire point of the technique before refrigeration.
The chemistry explains the look. The amber jelly of the white is denatured protein, clear because the alkaline environment prevents the cloudy conalbumin from aggregating. The green yolk is a combination of iron sulfides from the egg’s own sulfur and iron reacting under high pH. The faint ammonia smell is from protein breakdown, and it fades after the egg is peeled and rinsed.
What century eggs taste like
Honest description, because most people expect worse. The white tastes like a very mild, slightly salty egg-flavored jelly, close to a firm aspic with a faint cheese note. The yolk is the strong part: rich, umami-heavy, custardy, with an ammonia edge that reads as funky rather than rotten, similar to a washed-rind cheese. The overall experience is closer to eating a very ripe brie or a block of aged blue cheese than to eating a rotten egg, and people who like fermented foods usually take to them immediately.
The comparison to cheese is not accidental. Both are alkaline-protein transformations that produce glutamates and ammonia compounds, and both cuisines learned to love what the process creates. If you like stinky tofu, covered in the stinky tofu guide, you already have the palate for century eggs. If you like fermented bean curd, the same logic applies.
The classic ways to eat them
Century egg and pork congee
The definitive dish. Rice porridge cooked until silky, with diced century egg and lean pork stirred in at the end. The egg breaks into the congee and gives it a savory depth that plain congee lacks, and the result is the standard breakfast of Guangdong and the south. The congee guide is in the congee piece.
Cold tofu with century egg
Silken tofu, chilled, topped with chopped century egg, soy sauce, vinegar, sesame oil, and scallion. This is the most common home preparation, and it is the best introduction to the flavor because the cool tofu and the sharp dressing balance the egg’s richness. The tofu selection matters, and the options are in the tofu guide.
With pickled ginger
A Cantonese restaurant appetizer: century egg wedges served with pickled ginger slices. The sharp ginger cuts the funk, and the pairing is designed as a palate opener rather than a main.
The fermented egg family
Century eggs belong to a wider family of Chinese preserved eggs, and the comparison helps.
| Egg | Method | Texture and color | Common use |
|---|---|---|---|
| Century egg (pidan) | Alkaline cure, weeks | Amber jelly white, dark green creamy yolk | Congee, cold tofu, salads |
| Salted duck egg | Brine soak, weeks | Firm white, bright orange salty yolk | Zongzi, mooncakes, congee |
| Tea egg | Boiled in tea and soy | Marbled white, firm yolk | Street snack, breakfast |
| Quail egg, marinated | Short brine or sauce | Small, chewy, brown | Hot pot, snack packs |
Salted duck eggs are the one to know alongside century eggs, because their yolks appear inside zongzi during Dragon Boat Festival and inside mooncakes at Mid-Autumn, covered in the zongzi and mooncakes guides. They are much milder than century eggs and are the safe order for anyone nervous about alkaline funk.
Buying and handling century eggs
- Buy from a reputable brand; the lead-oxide contamination problem was real and persists with small unregulated producers, and labels in the EU and US market are tested for it
- Check the shell for cracks; a cracked egg dries out or spoils
- Peel under running water, then rinse the egg to remove paste residue and reduce the ammonia smell
- A good century egg has a springy white that holds its shape when sliced and a yolk that is creamy rather than hard and chalky
- Store at room temperature for weeks; refrigeration extends shelf life to months
If you are shopping in a Chinese supermarket abroad, the vacuum-packed eggs from Taiwan and Fujian producers are the reliable choice, and the ones sold loose in bins at wet markets in China are often fresher but vary more. The wet-market guide, wet markets, explains what to look for at the counter.
How to order without regret
The first century egg order that works for almost everyone is cold tofu with century egg at a restaurant that makes it regularly. You get the flavor balanced by cool tofu, sharp vinegar, and scallion, in small pieces. The order that fails is a whole peeled egg on a plate, eaten cold, by someone who was told it “tastes like chicken.”
If you are vegetarian, note that century eggs themselves are an animal product but contain no meat and no dairy, so they are fine for ovo-vegetarians and an excellent protein source when traveling in a cuisine that leans heavily on pork. The broader vegetarian guide is the vegetarian China piece, and century eggs over congee is one of the standard survival meals.
Frequently asked questions
Are century eggs rotten?
No. They are cured, not spoiled. The alkali preserves the egg by raising its pH beyond the range where spoilage bacteria survive, and the transformation is the same category as cheese or pickles. A properly cured century egg is safe and shelf-stable.
What do century eggs taste like?
The white is mild, jelly-like, and faintly eggy. The yolk is rich, savory, and custardy with a cheese-like funk. The overall flavor is closer to aged blue cheese than to anything else, and it is much milder than the smell suggests.
Do century eggs need to be cooked?
No. They are eaten after curing, straight from the shell, and are usually added to cold dishes or hot porridge at the last moment. Cooking them further would make the white rubbery and is never done.
Why is my century egg yolk hard instead of creamy?
It was cured too long or at too high an alkalinity. Older eggs have drier, chalkier yolks; fresh ones, cured for three to four weeks, have the creamy texture that is considered ideal. Check the curing date on the pack if it lists one.
Are century eggs safe to eat?
Yes, when bought from reputable producers. The one real risk is lead contamination from producers who illegally use lead oxide to speed curing; regulated markets test for this. Buy branded, packaged eggs, especially outside China, and avoid loose eggs of unknown origin.
Can I eat century eggs if I do not like strong-smelling food?
Maybe. Start with century egg congee or cold tofu with a small quantity of chopped egg, where the flavor is distributed and balanced. Avoid the whole-egg-on-a-plate version, which concentrates everything at once.
How long do century eggs last?
Weeks at room temperature and several months refrigerated, which was their original purpose. The curing process preserves them; the only thing that ruins them is a cracked shell or extreme dryness.
What is the best way to eat a century egg for the first time?
Century egg and pork congee at a Cantonese breakfast shop, or cold silken tofu with chopped century egg at a restaurant. Both balance the egg’s richness with mild starch and sharp condiments, and both are how most Chinese people first eat them as children.
Plan your own fermented food trip
Century eggs, stinky tofu, fermented bean curd, and pickled vegetables are a whole branch of Chinese eating that most tourists never enter. If you want a route built around breakfast counters, wet markets, and the fermented table, tell us your dates through the contact page and we will draft a custom food-and-travel itinerary around it.
Written by the ChinaTravelFood editorial team.
