Questions from the Public

Q:

The attached photo is an apple which was washed 3 times with a sponge, dishwasher liquid and a lot of water. The white stuff is still on the surface! Is that safe to eat, especially for children?

Regards
Reza Ahranjani, MD
Anesthesia research fellow
Women's College Hospital

A:

Apparently, Red Delicious and a few other types of apples have a natural waxy barrier, and there is a clay that is used as a barrier that is considered safe but can leave a dusty residue, as I learned from this site.

• All apples have an inherent wax barrier called cuticular wax which prevents moisture loss, enhances firmness retention and decreases the apples respiration rate. This cuticular wax production is higher in some varieties such as Red Delicious, Jonagold and Braeburn. Cuticular wax is also more prominent on apples of higher maturity. Although this wax is extremely beneficial, it can give a slight cloudiness to the finish of the apple and an oily feel to the skin. However, organic apples from Stemilt are not waxed.
• Kaolin clay is natural clay that is applied as a film to create a barrier between the pest and its host plant. This clay is processed to a very fine particulate size to enable it to be mixed with water. It is environmentally benign, worker-friendly and cost-effective as a tool to be used with integrated pest management. Kaolin clay also is used in toothpastes and in foods as an anti-caking agent. Kaolin clay is also an effective tool in reducing sunburn on apples, especially Granny Smith. Kaolin clay can leave a subtle deposit in stem bowls of the apples where the brushes did not reach during the cleaning process. The clay is harmless and safe.

Devra Davis, PhD, MPH
Director, Center for Environmental Oncology
University of Pittsburgh Cancer Institute