Food Safety Focus (63rd Issue, October 2011) – Food Incident Highlight

Nitrite and Nitrate Levels in Bird's Nest

Following up the incident of nitrites in blood-red bird's nest, a local university conducted a study on nitrite and nitrate levels in bird's nests revealing the presence of both chemicals in all 67 samples of bird's nests. The amounts varied significantly with blood-red bird's nests having the highest average levels.

In Hong Kong , nitrite and nitrate are not permitted to be added in bird's nest, but relevant regulation is not applicable to nitrite and nitrate naturally present in bird's nest. The mechanism of the natural presence of nitrite in bird's nest is not entirely clear. Some suggested that nitrite may be formed due to fermentation and the levels may vary with the extent of environmental contamination.

To alleviate public concern, the local university study also tested and confirmed that majority of nitrites and nitrates can be removed by washing and soaking. To reduce exposure to nitrites and nitrates, bird's nest should be washed and soaked for several hours or even overnight before cooking. Soaking water should be replaced once or twice during the process and be discarded.