How can I tell when the wax has been removed from citrus fruit?

Question

This evening I tried different ways (taken from other cooking forums) of removing the wax coating from lemons.

• Pouring boiling water over
• In a bowl with (initially) boiling water for five minutes
• Scrubbing with warm water and dishwashing liquid
• Scrubbing with warm water and ascorbic acid
• Scrubbing with warm water and baking soda.

After each trial I rubbed the lemons with a tea cloth. The methods involving boiling water produced slightly tacky, but less glossy lemons. The other methods made no obvious difference. No method really impressed me, and in the end I couldn't say if one method was better than another.

Before I experiment further, I would like to find a more objective technique for judging the results.

Some methods left the lemons looking as glossy as they were to begin with. Other methods left the skin feeling slightly tacky. Neither of these outcomes seems right to me, although I'm hampered by the fact that I live in a country where you don't see many lemon trees. I'm not quite sure how an unwaxed lemon looks and feels.

Is there some way that I can unambiguously tell whether the wax coating applied to prolong the shelf life of a citrus fruit has been successfully removed?

Answer 1

The best way to remove wax from citrus is simply to wash it with dish soap under warm, running water. Don't obsess about how long you should wash the fruit; usually the wax application is very thin and quickly removed.

There is no easy way to tell whether you have removed the wax, so if you return citrus to fridge after removing the wax, you might want to add a sticker to the fruit, or somehow indicate in another way that it has been washed, so that you know to use that piece of fruit promptly.

The true indicator that you have removed the wax is that the citrus will spoil more rapidly :(

Answer 2

There is unlikely to be any single answer to my question since the coating can be any one of a number of substances including,

• Natural or synthetic resins
• Carnauba wax
• Shellac
• Tall oil
• Paraffin
• Oxidised polyethylene
• Candelilla wax
• Beeswax
• Corn, soy or milk proteins

These may be disolved in a petroleum based solvent, emulsified with a detergent or modified with acids.

It seems that Lemons do indeed have a natural protective coating of wax that is removed during washing. A new coating is applied before packing, chiefly to improve shelf-life, but also to improve appearance and as a medium for post-harvest fungicides.

Coatings are differentiated by their shine, durability (preventing scuffing), ability to minimize fruit shrinkage, and how well the coating itself withstands drying out or breaking down.

A lemon that appears less shiny is not necessarily unwaxed, and it is difficult to say from outward appearances how easily the coat will come off. Needless to say, the coatings are designed not to come off, and some products will do a better job than others.

I tried out @ashes999's advice (which was given jokingly) and boiled a shiny waxed lemon until I was able to detect melted wax on the suface of the water. The lemon was still shiny and tacky when it came out of the water. Using dishwashing liquid and a scouring pad I scrubbed the hot lemon for a few minutes more and finally the tackiness was gone.

Comparing the boiled and scrubbed lemon to another I hadn't treated, I noticed no meaningful difference in appearance. There was however a difference to the touch. The untreated lemon left a slight waxy residue on my skin when I pulled my finger along its surface. The boiled lemon left no detectable residue.

My advice, for what it is worth, is to keep an untreated citrus handy if you are trying to remove wax, in order to compare results post-dewaxing. Compare by touch, rubbing a finger or thumb against the lemon surfaces applying a reasonable amount of pressure (say, enough to make 5mm depression)*.

_{* Note that there may be citrus coatings that feel the same before and after de-waxing. Or, alternatively, there may be coatings that impregnate the citrus skin to some extent and are never really removed. Like I said in my opening sentence, there probably is no single answer to this question.}