Chinese have always been particular about eating, with special emphasis on colour, aroma and flavour of food. In the course of food production, food manufacturers may add colouring matters into food so as to make them more attractive or restore their colours. Colouring matter is a kind of food additive and can be classified into natural and synthetic ones. It is difficult to distinguish one from another just from the appearance of the food.
Natural colouring matters are extracted from natural resources e.g. by extracting juice from flowers, fruits, stems and roots of plants, and grinded into powder after dehydration. Natural colouring matters are relatively unstable, low dyeing ability thus requiring higher dosage and are more expensive. Synthetic colouring matters are artificially synthesized. They are, generally speaking, more colourful, and more stable. Therefore, they are better preserved during food processing. Due to their high dyeing ability, the quantity used is relatively low.
In view of greater public concern over the safety of synthetic colouring matters, countries have exercised stringent control over those used for human consumption. Both natural and synthetic colouring matters can be safely consumed so long as they are properly applied to food.
The Purple Sweet Potato and Yellow Croaker Incidents
In response to the suspicious use of colouring matters in purple sweet potatoes and yellow croakers, the Centre for Food Safety has taken special actions to inspect various retail outlets including market stalls in the territory, during which samples of purple sweet potatoes and yellow croakers have been taken for laboratory testing.
Laboratory analysis reveals that all purple sweet potatoes contain a purple pigment known as anthocyanin. It is a naturally occurring colour found in purple sweet potatoes and there is no evidence that the colour has been added to them. In fact, anthocyanins are naturally present in many edible fruits and vegetables such as grapes, red cabbages and berries, and are generally innocuous for human consumption. Colour seepage when processing purple sweet potatoes is a natural phenomenon commonly found in vegetables and fruits, and is nothing to be worried about.
As for yellow croakers, among the various samples taken for analysis, only two obtained from the same retailer are found to contain Tartrazine and Sunset Yellow FCF. Under the Colouring Matter in Food Regulations, these two colouring matters are permitted in food but no colouring can be added to fresh fish in a raw and unprocessed state. Offenders shall be liable to a maximum fine of $ 50,000 and six-month imprisonment. We are following up the case and are considering instituting prosecution against the offenders.
In our regular food surveillance programme, samples were taken from different kinds of food product, including Chinese New Year foods. Among the food samples taken for analysis, a colouring matter known as Orange II, which is not permitted under the Colouring Matter in Food Regulations, was found added to Chinese puddings during production. Both the manufacturers and sellers concerned were prosecuted and convicted. During our follow-up investigation, samples taken from the same kind of food product did not detect such colouring .
According to the Colouring Matter in Food Regulations, citrus fruit may have in or upon it added permitted colouring matter provided -
- the words "colour added" are marked on the skin of such fruit in permitted colouring matter; and
- such words are distinctly and legibly printed and of such size as to be conspicuously visible.
Notes for Customers
Customers should pay attention to the following:
- Do not buy any food from unlicensed on-street hawkers.
- Purchase food from shops that you frequent or is reputable.
- Avoid food with abnormally intense colour or sold at an excessively low price.
- When cooking, check if the food colour remains abnormally brilliant.
- Do not buy or consume any food when in doubt.
Retailers should stop selling fresh food suspected to have colour added.
Complaints on food can be made to our district offices or by calling our 24-hour hotline on 2868 0000.