In some parts of the world food is stored with formalin so it looks fresh forever! This is astonishing, but true (See refs here). As formalin is very bad for health and damages kidneys and liver very quickly, I am looking for a way to remove it.

When I buy fish, I know it has formalin in it. Every fruit I bought has formalin. I remember I bought 2 kilgrams of apples once. And it lasted for 1 month, looking fresh whole time. Then I threw it away.

My question is: how can you remove formalin from food? (Especially fish and fruit). It's best if we can use a chemical found in the kitchen. If not, I'd think one that is found at a chemical store.

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    $\begingroup$ This is astonishing but true. Do you have a reference for that information? $\endgroup$
    – jonsca
    Commented Jul 14, 2012 at 20:14
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    $\begingroup$ Firstly, this formalin business sounds a lot like one of those hoax chain emails (though I can't find anything to support that). Secondly, are you sure that it is formalin? There are hundreds of other preservatives which can keep stuff fresh for a long time if added in sufficient quantity. Thirdly, I think that any chemical method of removing formalin will involve adding more harmful chemicals to the object, so that won't work either. :\ $\endgroup$ Commented Jul 15, 2012 at 2:48
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    $\begingroup$ @Manishearth - Consult this WP page and references therein. Outrageous, but then people put melamine in milk to fool protein tests. :( $\endgroup$ Commented Jul 15, 2012 at 9:08
  • $\begingroup$ @richard Oh, there is a lot of this where I live (fortunately, it's avoidable). Thanks for the WP ref--note that this doesn't ensure that the observed preservative is indeed formalin. But that's irrelevant to the question $\endgroup$ Commented Jul 15, 2012 at 12:25
  • $\begingroup$ @shiplu Remember, Googling stuff may not give reputable sources. I've seen hoaxes that get backed up by a quick Google Search. In this case, though, the refs on the WO article are good enough. Note that it's not just Bangladesh--Indonesia, Vietnam, and probably some other countries as well. $\endgroup$ Commented Jul 15, 2012 at 12:27

1 Answer 1


While the idea of filtering formaldehyde from food might sound naive, the motivation is understandable and the problem apparently real.

I've found at least one publication on the topic:

T Yeasmin, *M S Reza, M N A Khan, F H Shikha and M Kamal


Int. J. BioRes. 2010, 1, 21-24

From the abstract:

[...]Study showed that formalin was not detected in any fish produced locally, but was detected in the imported ones of catla and rohu ranging from 0.5% to 1% which was sold in different markets of Mymensingh with comparatively lower price than those produced locally. The shelf life of the locally produced fish was much longer than those of imported fish which may be related to the loss of shelf life during its transport from importing countries. [...]

Concerning the initial question: I'm afraid but i don't see any chance to remove formaldehyde from food without turning it to another toxic cocktail.

But since formaldehyde was mostly used to increase the shelf time of imported fish, buying from markets predominantly selling local products might be a way--if available and affordable.

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    $\begingroup$ ""ranging from 0.5% to 1% which was sold"" did You ever handle/smell formaldehyde? .5 % would render a fish unsellable due to the pungent smell. $\endgroup$
    – Georg
    Commented Jul 16, 2012 at 14:33
  • $\begingroup$ I do prefer the smell of geranial too ;) Seriously, whenever possible, i rather used paraformaldehyde in synthesis, e.g. for m-meconine on the route to fluorescent phthalimides. Even then, the synthesis isn't particular nice and thus best left to undergraduates :D $\endgroup$ Commented Jul 16, 2012 at 17:35
  • $\begingroup$ Sorry, but formaline is often used to kill parasites in shellfishes and other farmed animals, so the whole conclusion "But since formaldehyde was mostly used to increase the shelf time of imported fish, buying from markets predominantly selling local products might be a way--if available and affordable." is pretty questionable. $\endgroup$
    – Greg
    Commented Jul 23, 2014 at 0:13

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