Reader Valencia Seah wrote in to askST after buying some apples.
"As I could see a whitish layer on the skin, I used a knife to scrape it. Quite of a lot of white shavings came off and I had to go through a few rounds," she said.
"I did a bit of reading and it says that apples naturally produce wax, just like fruits like plums. But some producers do add wax to the apples too. I would like to check if it's safe for daily consumption and are consumers urged to scrape off the layer of wax before eating them?"
Food correspondent Eunice Quek found the answer.
Dr Wu Yuan Sheng, deputy director (pesticide residues section) of the veterinary public health laboratories chemistry department under the Agri-Food & Veterinary Authority of Singapore, explains that many plants, including the fruits and vegetables consumed daily such as apples, plums and pears, as well as citrus fruits such as oranges and lemons, have a natural protective layer of wax on their surfaces.
He says: "These natural waxes are not harmful to human beings."
To minimise moisture loss and extend shelf lives during shipment and storage, some fruits may be treated with a layer of commercial wax, adds Dr Wu. Several types of commercial wax can be used for coating fruits, and they may be food-grade wax or made of natural products.
He adds: "The use of industrial-grade wax for coating fruits is illegal as they may contain harmful impurities. The AVA, so far, has not found any fruit product coated with illegal substances."
For consumers who do not want to ingest the fruit wax, simply peel the fruits prior to consumption.