How fermented eggs were discovered is undocumented, but it is believed that they were invented out of the need to preserve eggs over a period of time. Scientists have estimated that their origin dates back 600 years, at the time of the reign of the Ming Dynasty in China. Fermented eggs have a dark colour and a rich, salty flavour. They are an acquired taste, much like blue cheese.
There are many stories about the origin of the fermented egg. One tale goes that a man in Hunan, China, found preserved duck eggs in the slaked lime clay that was being used in the construction of his house.
Originally, fermented eggs were just a means of preserving eggs, but over centuries the curing process was improvised to create a creamy texture and rich flavour so that they could become the Chinese delicacy they are today. They can be eaten on their own, or in congee.
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Traditionally made in China, Hong Kong and Taiwan, the eggs are preserved for weeks if not months using a mixture of salt, wood ash, clay and quicklime. This results in a chemical reaction that increases the sodium content and the pH of the eggs. During the fermentation, the egg white becomes gelatinous and turns dark brown or black, while the yolk becomes dark green. It’s a myth that fermented eggs are rotten because if made correctly, they are free of mould and are safe to eat. They are also called thousand-year eggs, hundred-year eggs, or century eggs.
Village farmers had fermented eggs for hundreds of years, but they only started appearing on restaurant menus in Hong Kong when some popular Chinese chefs fled to the city during the Chinese Civil War, bringing regional dishes with them, in the 1940s. One of Hong Kong’s most famous restaurants emerged during this time: the Yung Kee Restaurant, which specialises in fermented eggs. At the restaurant, fermented eggs are served as a starter accompanied by pickled ginger.
Sometimes, these eggs are also baked inside pastries. The recipe involved a fermented egg, pickled ginger and bean paste all covered in puff pastry dough. Baking this results in a crispy pastry covering with a soft egg inside.
Besides techniques used for the large-scale production of fermented eggs, the fermentation process has remained largely unchanged. Some companies have even been shut down for using harmful chemicals like copper sulphate just to speed up the fermentation process. It’s uncertain whether these eggs will remain on menus for the years to come because younger generations and tourists in China have been known to be wary of preserved foods.
