How does calcium carbide ripen mangoes?

For reasons of safe transportation of fruits, mangoes, bananas etc are picked before they ripen fully. Slightly green harvested mangoes are subjected to small containers of calcium carbide (CaC2) with a plastic covering. CaC2 reacts with the moisture in the air to release acetylene (or ethyne) gas, which like ethyleneis – a chemical substance produced by fruits to accelerate the normal process of fruit maturation – is a ripening hormone. Industrial-grade calcium carbide contains arsenic and phosphorus, and its use for the purpose of ripening is illegal in many countries.