Tuna is easier to sell red than brown so those involved in the trade are faced with a temptation to reverse the discolouration. One way to turn brown tuna red is to treat it with carbon dioxide. Tuna treated in this way was discovered in Europe in 2016. Illegally treated tuna may contain high amounts of histamine which can cause serious allergic reactions – histamines result from spoiling, something masked by faked reddening. Detecting these additives is not easy, however, Switzerland’s federal government asked a laboratory in Basel to run tests on samples taken from tuna sold in Switzerland.

Source: Le News May 30, 2019 10:30 UTC