Specialty duck eggs with red yolks may not be sold in Beijing, whereas all duck eggs, regardless of yolk colour, are banned from sale in Guangzhou, the capital of Guangdong province.
Chinese consumers pay more for eggs with red yolks as they believe the red colour is a sign of quality and better nutrition. Some people think that the eggs become red from the shrimp in ducks’ diets.
However Hou Shuisheng, a researcher from the Chinese Academy of Agricultural Science
, said that for ordinary eggs, â€œthe colour of the yolk should be light yellow. Both bright yellow and bright red yolks are not natural, so it is certain that some dyes have been addedâ€.
Initial test results showed Sudan-IV dye made up 46.5 percent of the ‘red drug’, according to the Institute of Food Safety under the Chinese Academy of Inspection and Quarantine.
The eggs were produced by farmers raising ducks on Baiyangdian lake, the largest freshwater lake in Hebei, and the main suppliers of duck eggs to Beijing’s markets and supermarkets.
The dye, which is commonly used in industrial products like flooring and shoe polish, has however contaminated food products around the world, and led to hundreds of product recalls in the UK last year.