Are Century Eggs Soaked in Horse Urine?

Century Egg
irrational_cat, Flickr

I love Japanese cookies and candies. I have come to the conclusion the Kasugai fruit gummy candies are dusted with crack rather than sugar because nothing should be that addictive (joking! it's sugar... at least I think so... let me taste another to check). When I stock up on candy at my favorite Asian market, I go down every aisle and sometimes try a new food. That is how I discovered Century Eggs.

A century egg, also known as hundred-year egg, thousand-year egg is a Chinese delicacy. A century egg is made by preserving an egg, usually from a duck, such that the shell becomes speckled, the white becomes a dark brown gelatinous material, and the yolk becomes deep green and creamy. The surface of the egg white may be covered with beautiful crystalline frost or pine-tree patterns. The white supposedly doesn't have much flavor, but the yolk smells strongly of ammonia and sulfur and is said to have a complex earthy flavor. I say 'is said' because I haven't tried a century egg yet. Oh, I would, but only if it was made right.

How It Should Be Done

Ideally, century eggs are made by storing raw eggs for a few months in a mixture of wood ash, salt, lime, and maybe tea with rice straw or clay. The alkaline chemicals raise the pH of the egg to 9-12 or even higher and break down some of the proteins and fats in the egg into flavorful molecules.

The ingredients I named are not the ingredients listed on the eggs that I have seen in stores. Those eggs are made from duck eggs, lye or sodium hydroxide, and salt. That sounds scary, but it's probably ok to eat. The problem is, the curing process can be accelerated by adding another ingredient to the eggs...

lead oxide. Lead oxide, like any other lead compound, is poisonous. This hidden ingredient is most likely going to be found in eggs from China, where the faster method of preserving the eggs is more common. Sometimes zinc oxide is used instead of lead oxide. Though zinc oxide is an essential nutrient, too much of it can lead to a copper deficiency, so it's not really something you want to eat either. How do you avoid poisonous century eggs? Look for packages that explicitly state the eggs were made without lead oxide. Don't assume the eggs are lead-free just because lead isn't listed as an ingredient. Personally, I'd avoid the eggs from China no matter how they are packaged because there is still a big problem with inaccurate labeling.

Give Them A Try

Many people avoid eating century eggs because of the rumor that they have been soaked in horse urine. I don't believe there is any horse urine involved, since urine is slightly acidic, not basic. If anyone knows otherwise, by all means post a comment. If you know of a good place to buy non-Chinese century eggs in the Myrtle Beach area, let me know. I'd love to try an egg, but I don't have any urge to incur heavy metal poisoning from the experience.

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Your Citation
Helmenstine, Anne Marie, Ph.D. "Are Century Eggs Soaked in Horse Urine?" ThoughtCo, Mar. 23, 2017, Helmenstine, Anne Marie, Ph.D. (2017, March 23). Are Century Eggs Soaked in Horse Urine? Retrieved from Helmenstine, Anne Marie, Ph.D. "Are Century Eggs Soaked in Horse Urine?" ThoughtCo. (accessed March 17, 2018).