I scrub waxed citrus fruit under hot water with a little washing up liquid added as I have been advised. Can I clean up unwaxed citrus fruit coated with imazalil in a similar way please? I use a lot of citrus zest in my baking so this question is important to have an answer.

  • How much is "a lot". Most recipes use less than a single fruits worth of peel in a whole cake – TFD Nov 3 '15 at 19:39
  • Imazalil is a suspected carcinogen, so is bacon – TFD Nov 3 '15 at 19:41
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    @TFD look up a classic lemon bar recipe, you'll be zesting 3 or 4 lemons for a standard batch of 8-12 bars. – Escoce Nov 3 '15 at 20:17
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    @Escoce that's a joke right? With that amount of fat and sugar, you shouldn't be worried about cancer from imazalil, your problem will be diabetes or heart disease – TFD Nov 3 '15 at 21:18
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    I was simply saying there are uses for that much zest in a recipe. I never mentioned anything about anything else. – Escoce Nov 3 '15 at 21:19

No, you can't wash it off. Part of it is probably that washing methods are not fully effective, another part is that there is diffusion into the fruit, and the diffusion is strongest in the uppermost cell layers. In oranges, this is the peel.

Table of pesticide residues From Kruve, A., Lamos, A., Kirillova, J., & Herodes, K. (2007, September). Pesticide residues in commercially available oranges and evaluation of potential washing methods. In Proceedings of the Estonian Academy of Sciences. Chemistry (Vol. 56, No. 3, pp. 134-141).

The same paper found 0.64 mg/kg imazalil content in orange peel and 0.04 mg/kg in orange pulp before washing. The regulatory allowed limit is 5 mg/kg. So if your fruit starts out with more pesticide than theirs - and it can legally be sold with 8 times more - the residue will be even higher.

If you want to follow safe food preparation practices, you have to use organic citrus fruit for zest. Non organic fruit can have pesticide residue from the growing period and still be labelled as "untreated" because it was not treated post-harvest.

If you are eating only the zest, you can happen to stay under the WHO acceptable daily dose, which is 0.05 mg/kg (human weight, not fruit weight). So if you're a 75 kg man1, you can eat a bit over half a kilogram of orange peel (if it doesn't exceed regulatory limits) and stay under the limit. But 1) you're also taking in the pesticide from the pulp, and while there's less in it, you're eating much more pulp than zest, 2) regulatory limits might be laxer where you live than in the EU, and 3) you're still poisoning yourself, even if it's not enough to become alarmed about it. Why consume one more carcinogen when you can avoid it?

1 it's less for women of childbearing age and children

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    That's really sad. Is there anything left safe to eat? – algiogia Nov 3 '15 at 19:39
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    Nothing is safe. You are more likely to get killed driving to the organic fruit store, or die from lung diseases from the fumes from your VW car, than get cancer from imazalil – TFD Nov 3 '15 at 19:54
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    @TFD and agliogia if you define "safe" as "zero risk", then of course nothing is safe, ever. This is why specialists are paid a lot of money to calculate an amount of risk which is seen as acceptable (a very difficult calculation) and this is labelled "safe" Safety is a matter of expert opinion and regulation, not a promise that nothing can happen. And people don't get cancer "from carcinogens", but the exposure to each of them increases their total risk. If you, personally, decide to expose yourself to a preventable risk, it's your right to do so. – rumtscho Nov 3 '15 at 20:12
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    @algiogia what!? you can eat a bit over half a kilogram of orange peel - do you have any plans to eat over a pound of orange zest in a day? Let's have some perspective please. – Mike G Nov 3 '15 at 20:25
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    @mikeTheLiar but it's also in the pulp. I know I won't die eating oranges, I not that stupid. But if you add everything up the future doesn't look bright – algiogia Nov 4 '15 at 12:58

Imazalil is a systemic fungizide that surpresses mold and bacterial growth, for example on the skin of citrus fruits.

As it is a known carcinogen, the consumption of citrus peels treated with it is not advisable, as stated here (in German, sorry) for example by the German a.i.d. (Governement supported agency).

I could not (yet) find a reliable source giving good information on the solubility of imazalil and the effectiveness of washing, so I stick to the official warning of "do not consume".

Without contrary proof, a variation of the basic food safety rule applies:
When in doubt, throw it out - that is, do not use the zest of treated citrus fruits.


Here in Germany, practically all Citrus fruit treated with any artificial coating (usually any combination of Thiabendazol, Orthophenylphenol, Imazalil) comes with a clear statement "Schale nicht zum Verzehr geeignet" - "Peel unsuitable for consumption". One should assume there is a reason behind that very unconditional statement.

Most supermarkets here will carry both treated and organic (I asked a clerk at an organic store about it, they definitely are not allowed to do wax or treat them in any way) varieties probably for exactly that reason; the interesting thing is that neither of them are immune to getting moldy, nor do any of them mold quickly when stored under normal pantry conditions. Also, citrus fruit that come without an organic label but with an explicit label of "Schale ist verzehrbar" - "Peel is edible","Unbehandelt - Schale nach der Ernte" - "Untreated (Peel, post-harvest)" are becoming common. Not 100% sure if there are waxed products around that state their peel is edible.

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    Many waxes are edible, and organic fruit is allowed to be waxed with beeswax but not petroleum derived products. So, it is possible that a waxed product states that its peel is edible - but then, the peel shouldn't be toxic. I'm not entirely sure about the regulations about the "peel is edible" label, what kind of pre-harvest treatment it allows, and what are the toxin limits for it. – rumtscho Nov 3 '15 at 20:15
  • So you are implying it might be more store/sourcing policy than law? – rackandboneman Dec 9 '15 at 13:01
  • There is a law, I'm pretty certain of that. But I can't really tell how much of what you describe is prescribed by law and how much of it happens to be how a single store does it. Separately, even for things which are covered in the law, the matter isn't as straightforward as it seems on first glance. If the law says "only fruit which has not been waxed after harvest can be labelled as 'untreated'", it is entirely possible that all organic farms have switched to waxing before harvest. – rumtscho Dec 9 '15 at 14:07

Imazalil has a limited shelf life (after application) I guess one should keep the fruit (citrus) in the fridge for a while (maybe a week? considering that it has been already stored for a week before you got to buy it from the store...) please read "Degradation of imazalil, orthophenylphenol and pyrimethanil in Clementine mandarins under conventional postharvest industrial conditions at 4 °C" Washing will not help much but like any fruit/product to be consumed should be thoroughly cleaned; I use warm soapy water & baking soda for mine in hope I remove most of the wax as well as possible germs.

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    What does it degrade into? Expired poison doesn't mean harmless :) – rackandboneman Feb 17 '17 at 9:56

How long do fungicides in wax on oranges take to degrade? That may solve a problem. Or just wash wax off hands after peeling. Our bodies are very good at getting rid of bad things.

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    This is already mentioned in Mark's answer, with a source instead of a question. The question is also not about wax on the hands. – user34961 Jan 30 '19 at 14:01

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