Quirky Foods Of The World: Century Eggs In China

The quirky foods of the world series aims to delve into the strangest culinary curiosities from across the globe. Last time we had a look at the polarising black pudding, but now we’ll be taking a look at China’s century egg.       

That’s right, an actual egg that’s preserved for eventual consumption over a hundred years… Ok no, that’s not entirely accurate!

Although otherwise known as the hundred-year egg or even the thousand-year-old egg, this ancient traditional Chinese preserved food is actually prepared in a mishmash mixture of quicklime, salt and ash, covered in clay and rice hulls – then left for several weeks or months at a time before it’s ready to be eaten.

Eggs from chickens, ducks or quails are mainly used for the creation of these eccentric eggs – so without further ado, lets crack them open and take a closer look…

Ancient accidental discovery

The exact origins of the peculiar preserved dish haven’t been fully verified, however it’s thought that the eggs have more than five centuries of production history.

According to legend, the initial discovery is said to have occured around six centuries ago, all the way back to the Ming Dynasty, somewhere in the Hunan Province. It was thought to have been entirely accidental, as a man allegedly came across a clutch of duck eggs, which had been submerged in a shallow pool of slaked lime.    

For some reason this person decided to give these eggs a tasting, and luckily liking what he’d found he decided to set about creating more, using salt to improve the flavour. This then resulted in the present day recipe of the century egg.

It’s more likely perhaps that the method for creating these eggs came from times when food was particularly scarce, increasing the need to preserve them by coating them in alkaline clay, which would harden to protect the eggs from spoiling.

Concocting a Chinese delicacy

The now traditional method of preparing the preserved eggs has evolved slightly from the ancient primitive process. As well as clay, an extra mixture of wood ash, salt and calcium oxide is used to speed things up. An infusion of tea using boiling water is also added to the mix, along with some quicklime. All of this ends up with a smooth paste being created and coated onto the egg, which is then rolled in a rice hull.

After the curing and aging process is complete, the egg is essentially encased in a hard crust – and ends up looking like something that’s been found during an archaeological dig. It’s yolk turns a dark grey-green color and the outside shell ends up a translucent brown due to the chemical mixture.

A common misconception was that the eggs were left to soak in horse urine, due to the pungent smell of ammonia. In fact Thai people actually called them ‘khai yiao ma’, meaning Horse Urine Eggs. However, the strong scent is simply caused by the combination of wood ash, quicklime and the other alkaline ingredients in the coating paste.

Cracking the controversy

Unfortunately, due to some unscrupulous practices amongst manufacturers – many of these eggs were found to contain high traces of lead. This was as a result of numerous small factories in China utilising heavy metals, like lead oxide, in order to artificially speed up the preservation process, along with the quality of the eggs.

This dangerous practice became rampant in some parts of the country but after the controversy went mainstream in 2013, many honest manufacturers would start labelling their products to indicate that they were free of lead. Thankfully, these days the majority of century eggs are cured without the use of those heavy metals.

A modern acquired taste

These days the Chinese century egg cuisine is still widely enjoyed in homes and restaurants, as well as sold in variations from local street vendors all around the country.

The eggs can be consumed on their own or mixed with other ingredients to make up a delightful dish. Sometimes the eggs are sliced up into wedges and served with shavings of pickled ginger for extra tangy flavour.   

More modern methods of curing the eggs consist of soaking them in a sodium hydroxide solution for around ten days, whilst being wrapped in plastic and left to age for several weeks.

Other variations to add to the classic preserved dish include – baking the eggs into pastries, deep frying them with stir-fried minced pork, chicken, or even in lots of corn dog batter so that they turn into a ball perched on top of a bamboo skewer.