Century eggs (also known as thousand-year eggs, century eggs, preserved eggs, or in Chinese 皮蛋 – pídàn) are a traditional food in Chinese cuisine that intrigues many people due to their appearance and name. Despite the name suggesting "100 years," they are not centuries old: they are typically preserved for a few weeks to a few months.
Below, you'll find a straightforward guide on what they are, how they are made, what they taste like, how to eat them, risks, benefits, and curiosities.
What are century eggs?
- They are preserved eggs (usually duck, but also chicken or quail).
- They undergo a chemical process that alters the egg white and yolk:
- The egg white becomes translucent, dark brown to black, with a gelatinous texture.
- The yolk becomes creamy, dark green to gray, often with an almost pasty texture.
- They are very common in China, Taiwan, Hong Kong, and in Chinese communities worldwide.
Despite their appearance, when prepared correctly, they are considered safe for consumption and used in numerous traditional dishes.
How are century eggs made?
The traditional process does not "rot" the egg; rather, it preserves it through an alkaline environment.
Traditional process (classic method)
Historically, a mixture of:
- Clay
- Wood ash
- Quicklime (calcium hydroxide)
- Salt
- Rice straw
The eggs were covered with this paste, rolled in straw, and left in a cool place for several weeks or months. The alkaline medium alters the proteins and fats in the egg, resulting in the characteristic texture and color.
Modern methods
Today, the industry uses more controlled processes, typically involving:
- Alkaline solutions (such as sodium or potassium hydroxide in controlled concentrations)
- Salt
- Occasionally approved food colorings, to standardize the appearance of the shell
These methods shorten processing time and increase product safety and consistency.
Are century eggs really 100 years old?
No. The name is a poetic hyperbole.
- Typical preservation time: from 3 weeks to a few months, depending on the method.
- English terms:
- century egg
- thousand-year egg
- preserved egg
The exaggeration in the name helps give it an exotic flair, but in practice, it's just an egg preserved for months, not centuries.
What does a century egg taste like?
The flavor is intense and distinctive, and often causes strangeness the first time:
-
Aroma:
- Characteristic, strong, slightly ammoniacal or sulfurous.
- For some, it resembles strong-smelling cheeses.
-
Flavor:
- Pronounced umami, salty, slightly earthy.
- The yolk is rich, creamy, with a complex flavor, sometimes reminiscent of aged cheese or mild liver.
- The egg white is more neutral, with a slight bitterness in some cases.
-
Texture:
- Egg white: gelatinous and firm, like an elastic jelly.
- Yolk: creamy, almost like a pâté or a very soft-boiled egg yolk, but denser.
Those who get used to it often find it addictive, especially when combined with accompaniments that balance the flavor (such as cold tofu, ginger, and scallions).
How to eat century eggs?
The century egg is almost always consumed ready-to-eat, with no need for additional cooking. Some popular ways to consume it:
1. Century egg with cold tofu (classic pub dish – 皮蛋豆腐)
A typical dish in Taiwan and China:
- Soft tofu (silken tofu), chilled
- Chopped century egg
- Soy sauce, rice vinegar, sesame oil dressing
- Grated ginger, scallions, and sometimes cilantro
It's a great way to try it for the first time, because the tofu and sauce balance the strong flavor of the egg.
2. Rice congee with century egg (皮蛋瘦肉粥)
One of the most traditional dishes:
- Rice porridge (congee or zhou)
- Shredded pork
- Pieces of century egg
- Finished with scallions, ginger, sometimes sesame oil
It's a very common comfort food for breakfast or on cold days.
3. In salads and cold appetizers
- Cut into wedges, served with:
- Pickled ginger
- Soy sauce, vinegar, and chili oil dressing
- Fresh herbs
4. In modern creative preparations
In contemporary Asian cuisine restaurants, you might find:
- Century egg in:
- Ravioli and gyoza
- Risottos with an Asian twist
- On toast, like "Asian bruschetta"
- In sauces and pastes (by mashing the yolk)
Is it safe to eat century eggs?
When produced correctly, within sanitary standards, yes, they are safe.
What might be a concern
-
Excess sodium
- Most preserved eggs are quite salty.
- People with hypertension or salt restrictions should consume in moderation.
-
Ammonia content
- The "ammonia" smell comes from protein breakdown.
- At controlled levels, it's expected; however, if the smell is extremely strong and too unpleasant, or if there are signs of deterioration, do not consume.
-
Artisanal products without sanitary control
- The greatest risk lies in eggs made without hygiene or without control of chemical ingredients.
- Prefer:
- Known brands
- Products with labels from reliable Asian stores
-
Egg allergy
- Those who already have an egg allergy should avoid them; the egg is still an egg, just preserved.
To reduce doubts, it is interesting to check food safety norms and guidelines from official bodies such as the World Health Organization and local food safety legislations.
Nutritional value of century eggs
The basic nutritional value is similar to that of a common egg, with some differences due to the process:
- Proteins: still a good source of protein.
- Fats: mainly present in the yolk, as in a normal egg.
- Sodium: tends to be higher, due to the salt in the preservation process.
- Vitamins and minerals: still contains B vitamins, selenium, and other minerals, but some sensitive vitamins may be altered.
Therefore, consumption should be moderate, especially for those with heart or kidney problems or who need to control salt intake.
How to choose and store century eggs
How to choose
- Buy from reliable Asian stores or large supermarkets.
- Check:
- Expiration date
- Integrity of the packaging
- Label information (ingredients, manufacturer, country of origin)
How to store
- Store in a cool place or in the refrigerator, as per manufacturer's instructions.
- Once peeled:
- Store in the refrigerator, in a sealed container
- Consume within 1–2 days for best flavor and safety
Can I make century eggs at home?
While there are recipes circulating on blogs and videos, it is not recommended to try to reproduce the complete traditional method at home if you do not have deep knowledge of:
- Handling strong alkaline substances (such as sodium hydroxide)
- pH control
- Good hygiene and preservation practices
Potential risks:
- Bacterial contamination
- Chemical burns to skin/eyes during preparation
- Final product unsuitable for consumption
If you want to try them safely, the best option is to buy ready-made century eggs from reliable brands.
Curiosities about century eggs
- They are considered delicacies in many places, not just "exotic food."
- The shell, after the process, sometimes shows patterns resembling flowers or crystals in the egg white when cut, poetically called "snowflakes" or "pine blossoms."
- In some Chinese banquets, century eggs are served as a decorated cold appetizer, in wedges, alongside cold cuts and pickles.
Where to read more about century eggs
If you want to delve deeper, understand the chemistry of the process, or learn more about the history of the dish, some English resources are particularly useful (in addition to books and articles on Chinese cuisine).