Nine Lunar New Year food samples have failed chemical tests by the Centre for Food Safety.

Three samples of sweetened winter melon, two of bamboo fungus, a dried daylily flower and a sweetened mandarin were found to contain excessive levels of preservative sulphur dioxide. A festive cake was found to contain preservative benzoic acid, which banned in such food, while a glutinous rice ball with peanut filling was found with excessive aflatoxins.

Sulphur dioxide and benzoic acid are commonly used as preservatives but are only allowed in specified foods. Sulphur dioxide is also used as a bleaching agent. Aflatoxins can be found in nuts and cereals if they are contaminated by a specific type of mould which can be toxic.

For the sulphur dioxide in the bamboo fungus and dried daylily flower, most of the chemical, which is water soluble, can be removed after thorough soaking, washing and cooking. As for the other samples found containing sulphur dioxide, benzoic acid or aflatoxin, the levels detected are low and should not cause immediate health effects with normal consumption.

The centre has issued letters to the shops selling the products warning them to stop their sale and is tracing the source of the food.

The items were among the 234 samples taken for microbiological and chemical tests, 96% of which saw satisfactory results. All microbiological tests were passed.