Does wax on citrus fruit make the zest unsafe to eat or compromise its flavor? A number of (chiefly British) recipes specify unwaxed lemons for zesting. Unwaxed citrus fruit are not widely available here in Sweden, so I have to make do by attempting to remove the wax before zesting. Recently I have had doubts regarding the extent to which I actually succeed in doing so, and now I wonder whether it is even worth the trouble.

Citrus fruit have a natural wax coating that is washed off along with orchard grime at the packing house. A new protective coating is applied before packing, and it is this that I am concerned about.

I have two concerns. First there is a food safety issue. Reading the FDA and EU food additive regulations, I see that some substances are permitted for citrus and fruit such as apples and pears where the peel is normally eaten. Other substances are only to be used on citrus or other fruit where the peel is not normally ingested. On the face of it this seems to suggest that the consumption of citrus peel has not been taken into account. I understand that this may not be the case, but since neither regulatory body clarify the issue (at least not in the linked documents), I feel my concern is warranted.

My second concern is regarding whether the taste of the peel is compromised by the coating. This is a tricky question for me to answer since I have no access to untreated citrus. There is the additional difficulty that there are so many substances permitted, and the supermarkets here give no indication of what is used. Presumably some types of coating taste better and others worse. I include this part of question with the faint hope that there may be someone reading who is not subject to the same limitations.

Is it worth bothering even trying to wash the wax of citrus?
I recently did some experimenting on this exact topic. I can't contribute anything to the safety part of your question, but I have some notes regarding flavor.

The experiment: I blind tasted lemon zest in a group of associates and friends with varying degrees of palate development. Most people were able to differentiate between fresh zest with wax and fresh zest without. Nobody could tell the difference once we'd incorporated the zest into a dish, probably since the wax reflows and becomes very diluted. The experiment didn't eliminate every possible variable or control for every factor, but I thought I'd pass this along in case it's useful to you.

In my personal experience - when I compare waxed and unwaxed citrus fruit side by side - the taste of fresh zest is slightly bittered by the presence of wax. Mouthfeel is appreciably gummier and I find it harder to perceive the zest's moisture as well.

If enough of us perform this experiment we could cobble together our own unofficial data :) I'd be more than happy to crunch the stats.