What is the blue or grey dust on plums and grapes?

[Second Summer]

I was a bit worried yesterday when I was eating a plum and discovered it had a lot of blue-grey dust stuck to the skin. Today I had been sent yet another plum in my lunch pack which had the same blue-grey dust. So I decided to search the Internet and found this:

The term glaucous is also used botanically as an adjective to mean "covered with a greyish, bluish, or whitish waxy coating or bloom that is easily rubbed off" (e.g. glaucous leaves).

The epicuticular wax coating on mature plum fruit gives them a glaucous appearance. Another familiar example is found in the common grape genus (Vitis vinifera). Some cacti have a glaucous coating on their stem(s). Glaucous coatings are hydrophobic so as to prevent wetting by rain. Their waxy character serves to hinder climbing of leaves, stem or fruit by insects. On fruits, glaucous coatings may function as a deterrent to climbing and feeding by small insects in favor of increased seed dispersal offered by larger animals such as mammals and birds.

Glaucous - Wikipedia

So there you have it, it's completely natural and presumably not harmful to humans

 

[shyvas]

I was a bit worried yesterday when I was eating a plum and discovered it had a lot of blue-grey dust stuck to the skin. Today I had been sent yet another plum in my lunch pack which had the same blue-grey dust. So I decided to search the Internet and found this:


Glaucous - Wikipedia

So there you have it, it's completely natural and presumably not harmful to humans

You also get this greyish dust on grapes.