Food

Century eggs: What are they made of and where are they from?

Sep 17, 2019

Considered a delicacy in China, preserved eggs would not win an award for visual appeal, with their translucent dark exterior that has a jellylike texture, and a greenish-black oozing yolk with a hint of ammonia.

James Corden, host of The Late Late Show with James Corden, frequently uses these eggs in his “Spill Your Guts or Fill Your Guts” segment, threatening to feed them to his guests if they don’t answer personal questions.

What Corden doesn’t know, however, is that when the eggs are of good quality, they taste absolutely delicious.

Also known as century egg, hundred-year egg, thousand-year egg, skin egg, and black egg, the preserved egg is served in the most humble of establishments through to restaurants with three Michelin stars.

“It tastes like egg on the palate, with a creamy and succulent flavor.”

Chef Cheung Long-yin

“It gives an acquired fragrance of egg, with a slight odor of ammonia,” says Cheung Long-yin, executive Chinese chef at the Kowloon Shangri-La, “but it tastes like egg on the palate, with a creamy and succulent flavor.”

Preserved egg with tofu.
Preserved egg with tofu. / Photo: Shutterstock

Cheung says the ideal egg should have a slightly runny, gooey, and creamy egg yolk, with small traces of the yolk sticking to the knife after cutting the egg in half.

Accidental origins

Preserved eggs have a history dating back to the Ming Dynasty (1368-1644) and most likely originate in central China’s Hunan Province.

“In China, methods have been developed to preserve eggs in such a way as to cause chemical and physical changes in both egg white and yolk, imparting a new flavor,” wrote Hou Xiangchuan in the peer-reviewed academic journal Food and Nutrition Bulletin. “The earliest known description of an egg preservation method is that of Wang Zizhen during the Ming Dynasty.”

Preserved egg in congee.
Preserved egg in congee. / Photo: Shutterstock

Like many foods or dishes with a long history, the origin of preserved eggs is said to be accidental. There are several variations of the tale.

One tells of a homeowner discovering duck eggs in a shallow pool of slaked lime used for mortar two months after construction—and then proceeding to taste the eggs.

Another involves a man who accidentally spills his tea (with tea leaves) in ash where his ducks laid their eggs. After cleaning the ash, he finds some eggs he previously missed and decides to try them.

(Read more: ‘We took it off the menu because it was a little weird’: Junzi Kitchen head chef on selling century egg to New Yorkers)

While the stories differ, most variations agree that upon trying the eggs, the originator thought the flavor would be improved with the addition of salt.

A common misconception is that the preservation method originally involved horse urine. (Interestingly, the direct translation of the name for the eggs in Thailand and Laos is “horse urine egg,” most likely due to the associated ammonia smell.)

But traditional preservation methods usually involve raw eggs, ash, salt, slaked lime, clay, and rice husks, methods that are still practiced today.

Preserved eggs are traditionally made with ash, salt, slaked lime, clay, and rice husks.
Preserved eggs are traditionally made with ash, salt, slaked lime, clay, and rice husks. / Photo: Shutterstock

However, with more understanding of the chemistry behind the process, there have been simplifications, which achieves the same result in weeks instead of months.

How to eat them

A typical way to enjoy the eggs is by pairing them with pickled ginger.

“There are several elements,” says Chan Yan Tak, executive Chinese chef at the Four Seasons in Hong Kong. “The egg is alkaline from its preservation process, and the acidity in pickled ginger brings it to a balance. In terms of texture, the egg is silky smooth, so when you eat it with crunchy pickled ginger, it enhances the flavors.”

Preserved eggs are also served as a topping for congee, said to be a good introduction for novices.

(Read more: Preserved vegetables and other Hakka dishes, illustrated)

Numerous other dishes also include the eggs.

In Shanghai and Taiwan, they are combined with cold silken tofu, light soy sauce, young ginger, and sesame oil.

In Hong Kong, they can also be found in pastries as well as mooncakes.

Adapted from an article first published in STYLE.

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