Warning issued on traditional pickling

Contamination risk

Ruan Guangfeng, a food safety expert from the China Food Information Center, considers pickled food produced by factories, where there are strict rules for sanitary conditions and the fermentation period, to be safer than that made at home.

"All homemade fermented food has the risk of bacterial contamination, so I don't recommend making it," Ruan said.

"If you do want to make pickled food at home, you first need to learn about food safety, such as the need to often change the water when marinating grains, and that storage areas should be well ventilated and damp-proof," he said.

Making such food at home comes with safety risks. Nitrite, a salt of nitrous acid, is a major concern in pickled food, while bacteria and methanol can form in homemade wine. In smoked fish or preserved meat, excessive levels of the organic compound benzopyrene can cause cancer.

Ruan said studies have shown that as fermenting progresses, nitrite content is gradually reduced until it is almost undetectable.

"If the food is fermented long enough, there should be no worries about nitrite content. So, avoid eating food that has just been pickled, and instead wait for at least two weeks," Ruan said.

He added that whether or not there is nitrite in pickled food, there is still a high salt content, so people should not eat too much of it.

"Pickled food can also be used to replace salt in cooking, as it not only brings out unique flavor, but also adds minerals and dietary fibers to a dish," he said.