Century egg in the radar

Since a few years ago, I've become very sceptical of food products that are imported from China. The melamine milk scare is still very fresh in my mind, and I've known of Chinese traditional medicinal products being laced with unknown quantities of lead and mercury compounds. As far as I'm concerned, I steer very clear of edible Chinese imports, including vegetables and fruits, as much as possible.

The latest food scare staring me in the face concerns an imported delicacy: the century-old egg. Of course, the preserved egg is anything but a hundred years old. But it has been processed until it looks murky grey on the inside and transparent brown on the outside. Westerners are often turned off by it but we of Chinese descent love them. Well, most of us, anyway. Century-old eggs are best savoured with pickled ginger root slices while the preserved yolk itself is still a little runny.

But like all good delicacies go, it may be time to relook into our eating habits. According to a news report by the South China Morning Post in Hong Kong, there is a fresh food scandal in China and it may have repercussions here too, if our century-old eggs are imported from that land.

Thirty companies in Jiangxi province, China, producing preserved eggs were closed by authorities there after it was exposed that industrial copper sulphate, a toxic chemical, was used to speed up production. The eggs at the plants in Nanchang county have now been locked away for further testing, and authorities are screening small processing workshops without licences.

A report by state broadcaster China Central Television on Friday showed that three plants producing preserved duck eggs - also known as hundred-year egg, century egg, thousand-year egg, thousand-year-old egg and millennium egg - were using industrial copper sulphate to halve the curing period to a month. This chemical usually contains high levels of toxic heavy metals, including arsenic, lead and cadmium, and so is banned for use as a food additive.

When I was small, my grandparents used to tell me that the eggs were traditionally preserved in straw soaked with horse urine but I don't know how true it was. Later, the producers turned to preserving the eggs with baking soda, salt and quicklime for about two months. Either process would turn the yolks' colour dark green and the egg white into a stiff, dark jelly. Using copper sulphate could significantly reduce the processing time while achieving the same effect.