Soap nuts [Photo by Pauline D. Loh/China Daily]

Soap beans, soap nuts, soap pods are just some of the literal English names for something the Chinese call zaojiao, the fruit kernels of the Gleditsia sinensisit tree, or the Chinese honey locust.

It is a tree whose leaves, thorns and fruit have been used widely in traditional Chinese medicine, as far back as 2,000 years ago.

The long thorns have antibacterial properties and were used in the treatment of inflammatory and skin diseases. Modern scientific research suggests they may also be anti-carcinogenic.

It is the fruits that are popularly sold online now, as "nature's collagen supplement". This is the soap nut or soap bean, long used by the locals as a natural all-organic detergent.

But, it is also delicious used in a dessert sweet soup, boiled with white fungus, Chinese jujubes and rock sugar. Perhaps the "collagen" advantage was arrived at because the fruit cooks to a chewy, soft gelatinous texture that is very easy on the taste bud.

Certainly, the Shanghai ladies, always the fashion leaders, are buying it in vast quantities on China's popular Web shopping mall, Taobao.com.