
If you plan on heading to China or any of the surrounding countries in the future, you should keep your eyes peeled for a certain egg-based cuisine. You’ve heard of Green Eggs and Ham, but have you ever heard of black eggs? I suppose you could eat them with ham, but something tells me that’s not what they do in China.
Anyway, these black eggs are called “century eggs,” and they’re black, strange-looking, and totally delicious. Sure, it’s only natural that someone should be put off by a black egg, especially considering that most foods that turn black are moldy or rotten. However, that’s not the case with these century eggs.
Century eggs are not the result of mold or rotting, but rather a chemical process involving alkaline salts that turns a boring old egg into something bursting with complex flavor. Sure, it might look a little offputting, but, trust me, they’re absolutely delicious and 100% worth trying if you can get your hands on one.
What Are Century Eggs?
Century eggs, also known as preserved eggs, black eggs, hundred-year eggs, millennium eggs, and thousand-year eggs, are not actually 1,000 or even 100 years old. The process of making century eggs involves soaking duck, quail, or chicken eggs in a saline solution and usually only takes a few weeks or a few months. As a result of this process, the yolk turns into a dark-green or grey color and the white becomes brown translucent jelly.

Century eggs often have a much creamier texture than normal eggs, almost like an aged cheese. The flavor of the yolk gains a much stronger flavor from the preserving process while the white becomes a wonderful salty compliment.
Traditionally, century eggs can be eaten with pickled ginger root or in congee, a traditional rice porridge. You can also eat them alone if you want to isolate the flavor and fully understand what century eggs are all about.
These days, century eggs have made their way into fine dining. Kowloon Shangri-La, a luxury resort with a Michelin-star restaurant, serves mooncakes filled with century eggs. Their century eggs have been preserved for less time, though, and so have a golden coloration that’s more appealing to international customers.
Common Misconceptions About Century Eggs
Despite the fact that they’re called century eggs or sometimes millennium eggs, this cuisine does not actually take that long to prepare. The real process of making century eggs usually only takes a few weeks.
That’s not the only misconception about century eggs, though. Due to the fact that the word for century eggs in the Thai and Lao languages translates to English as “horse urine eggs,” many people falsely believe that the dish is made by soaking eggs in horse urine.
Where exactly this rumor started is unknown, but it’s entirely unfounded. This name comes from the fact that century eggs smell of ammonia, a common ingredient in urine, giving the eggs a urine-like smell. Urine, however, is typically not alkaline, and so would not work for producing century eggs.

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As a side note (and you should skip this paragraph if you’re squeamish) there is another egg-based dish from China that actually does involve soaking eggs in urine. They’re called virgin boy eggs and they’re made by soaking eggs in the urine of peasant boys under the age of ten from the city of Dongyang. There’s no specific reason why it has to be the urine of young boys, it’s simply been a tradition for centuries.
The History of the Century Egg
According to folk history, the century egg dates back about 600 years to Hunan during the Ming Dynasty. As the story goes, a man discovered several duck eggs in a pool of slaked lime near his house, which he had been using to mix the mortar to construct his house two months earlier.
For some reason, he decided it would be a good idea to taste these eggs even though they were black and sitting in a pool of chemicals. Luckily, he discovered that the eggs were not only not poisonous, but actually quite delicious. The man decided that he had to start making more of the delicious cuisine, and thus the tradition of century eggs began.
In an alternate origin story, it is said that a young duck farmer once left several duck eggs in a woman’s garden as a courting gesture. Songmei, the woman being courted, did not discover the eggs in the ash pit where the farmer left them until two weeks later. In another daring feat, she ate the several-week-old eggs from the ash pit and found that they were delicious. In honor of Songmei, century eggs that have a pine-like pattern around the edges are often called “Songhua.”
How to Make Century Eggs
Since the accidental discovery of century eggs, the formula has been improved by adding other flavoring agents. Traditionally, century eggs are made by rolling each individual egg in a mixture of wood ash, calcium oxide, salt, and clay by hand. Whoever is applying the mixture usually wears gloves to avoid getting chemical burns.
The egg is then rolled in rice chaff, which prevents them from sticking to each other after they’re packed into cloth-covered jars or baskets. They’re left to sit for several months while the mud-like substance gradually hardens around each egg. Finally, the crust is carefully broken off and they’re ready to eat.

These days, however, the process of making century eggs has been simplified. The most common way to prepare century eggs is by simply soaking them in a solution of table salt, calcium hydroxide, and sodium carbonate for ten days. Then, you take the eggs out of the solution and leave them wrapped in plastic for several weeks. This process is said to achieve the same effect as the traditional method.
Is It Safe to Eat Century Eggs?
It is entirely safe to eat century eggs as long as they’re prepared the right way. Nothing about the traditional chemical process used to make this cuisine is harmful to humans. There have, however, been instances of malpractice in the century egg industry that had the potential to make people very sick.
In 2013, it was found that three factories in Jiangxi were using copper sulfate to shorten the production time of their century eggs. Three people were arrested and four businesses were shut down in the incident.

With that being said, you have nothing to worry about with century eggs. They won’t make you sick and they aren’t covered in mold. They’re actually very delicious. So, if you find yourself in a position where you can try one, go for it!
Disgusting and gross