Happy bicentennial Singapore – with 2 century eggs. Century eggs is actually a misnomer. These eggs are made by immersing eggs (chicken, duck or quail) in a mixture of clay, ash, salt, quicklime, and rice hulls for several weeks to several months. Pi dan is hence an alkaline egg.

The process of preservation elicits chemical reactions which release ammonia and hydrogen sulphide. When I was a kid, the adults told me that pi dan were made by immersing eggs in horse urine – hence the smell of ammonia.

Like many fermented foods, the taste for pi dan is strictly acquired. Those who don’t like it will say that it stinks. Those who like it say that it has complex flavours. Indeed, if you add sliced preserved ginger to it, the taste gets even more complex.

Some consider century eggs a health hazard. Heavy metals have been used to speed up the process to turn more profit in less time while artificially improving the appearance of the preserved egg.

This unscrupulous practice was common in some small home factories in China. To distinguish themselves, reputed manufacturers label their boxes “Lead Free”. It is best to only buy century eggs which have been ethically produced and certified by a trusted authority.