Excessive preservative of sulphur dioxide was found in four samples of dried lily (乾金针) drawn from the market.
This was revealed in a Consumer Council test on some of the dried vegetables favoured by the local population in vegetarian dishes for the Lunar New Year.
The test covered altogether 42 samples comprising 9 bean curd sheets ( 腐竹), 9 tremella (white fungus 腐竹),12 dried cole (white cabbage白菜乾) and 12 dried lily (乾金针) , common in family meals for the festive occasion.
Sulphur dioxide is used commonly as a food preservative. Sensitive individuals may develop symptoms like asthma subsequent to consumption of sulphur dioxide.
Because of the health concern, its quantity in foodstuffs is controlled under the Preservatives in Food Regulations Cap. 132 BD.
The chemical was found in 23 of the 42 samples in the test. But only four dried lily samples were detected to contain sulphur dioxide ranging in quantity of 2,286ppm, 2,464ppm, 2,575ppm and 4,897ppm, which exceeded the statutory limit of 2,000ppm.
Based on the Acceptable Daily Intake stipulated by the Joint FAO/WHO Expert Committee on Food Additives, a 60 kg adult should consume not more than 42 mg of sulphur dioxide.
This means that for the sample with the highest sulphur dioxide content, a quantity of about 8.6 g or a mere 17 strands of dried lily would have reached that limit.
Consumers, however, need not worry unduly as preparation of dried lily usually involves soaking, rinsing and cooking that will effectively reduce the sulphur dioxide content of all dried vegetable products.
Sulphur dioxide was also found present in bean curd sheets, in which it is not allowed to be used as a preservative under the aforesaid Regulations. This is due to the use of a bleaching agent known as sodium hydrosulphite which leaves sulphur dioxide as a residue.
But none exceeded the permitted residue level of 200ppm, which was set by the FEHD with reference to the mainland standard GB 2760.
Furthermore, the test found traces of formaldehyde, ranging from 1.0ppm to 56.8ppm, in 32 of the samples. Formaldehyde is forbidden to be used as preservative.
In the opinion of the FEHD, the formaldehyde content of these samples was consistent with the records in scientific literature. Therefore, it is possible that the formaldehyde detected is naturally present in the original vegetables and not added deliberately during the production process.
In light of the test findings, manufacturers are urged to carefully control the amount of sulphur dioxide added to dried vegetable products.
Consumers, on the other hand, should bear in mind the importance of a balanced diet in order not to take in an excessive amount of sulphur dioxide or formaldehyde through consuming a particular food item.
They should also always follow the proper way to prepare vegetarian dishes by thoroughly soaking, rinsing, and cooking - in particular dried lily.
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