If you live in an area where there is a large population of Chinese people you may have heard of, or seen in stores, 100 year old eggs. Being as the human population 100 years ago was no where near what it is today, it is very unlikely people thought ahead to save up that many eggs for the future, so just how old are 100 year old eggs?
100 year old eggs are sometimes called century eggs, 1000 year old eggs, and millennium eggs. Under any name, they are not as old as they say. In fact they are more like 100 days old than 100 years. They are sometimes called horse urine eggs, although horse urine is not used to make these eggs and perhaps refers to their odor or an early mistaken belief that horse urine was used to make these eggs. In Chinese they are also called leather skin eggs and pine pattern eggs.
Eggs, when not kept chilled, and when exposed to air (egg shells are actually somewhat porous), tend to go rotten after a few weeks. As such preparation of the 100 year old egg had its roots in early food preservation.
According to legend a man was getting ready to build a home in the Hunan province of China, over 1,500 years ago. He is said to have found duck eggs in mud and lime preserved in the mud that was being used to build his home, he tasted them and enjoyed them, and sought to create this as a food. He found that coating eggs in mud kept them edible for a long time and due to the porous nature of eggs, they would take on the taste (and colors) of the mud used to preserve them.
In the traditional method 100 year old eggs are made by mixing wood ash, salt, tea, and quicklime, into the mud and then covering the eggs. The muddy eggs are rolled in rice husks so that each one does not stick to the others. They are left to sit for 3 months, or more, during this time the egg white turns golden in color and the yolk becomes a grayish green. Once preserved this way the eggs can last for a year. Modern methods of preparation have sped up the process but the traditional method is often preferred and still in use today.
100 year old eggs are usually served at room temperature, either alone or in another dish.
100 year old eggs can be made from any kind of egg; chicken, duck, and quail eggs are the ones most commonly used.
photo source - century egg
Although they are well preserved, 100 year old eggs would not last 100 years; they will eventually go bad. When rotten they smell extra potent and the white part tends to look green and/or be somewhat liquid-like.
Have I Tasted 100 Year Old Eggs?
Yes, I have tasted 100 year old duck eggs and I must say I did not care for them. I am a fairly adventurous eater and my parents had many Asian friends who introduced us to their authentic ways of cooking and authentic foods (not those you find in fast food Asian restaurants). I found they tasted like dirt and had no interest in trying them again.