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Ripening is a process in fruits that causes them to become more palatable. In general, a fruit becomes sweeter, less green, and softer as it ripens. Even though the acidity of fruit increases as it ripens, the higher acidity level does not make the fruit seem tarter, which can lead to the misunderstanding that the riper the fruit the sweeter. This is attributed to the Brix-Acid Ratio.
Ripening agents speed up the ripening process.
They allow many fruits to be picked prior to full ripening, which is useful, since ripened fruits do not ship well. For example, bananas are picked when green and artificially ripened after shipment by being gassed with ethylene.
Calcium carbide is also used for ripening fruit artificially in some countries. Calcium carbide reacts with water to produce acetylene, which acts as an artificial ripening agent. Industrial-grade calcium carbide may contain traces of arsenic and phosphorus which makes it a human health concern. The use of this chemical for this purpose is illegal in most countries. 
Catalytic generators are used to produce ethylene gas simply and safely. Ethylene sensors can be used to precisely control the amount of gas.
Covered fruit ripening bowls are commercially available. The manufacturers claim the bowls increase the amount of ethylene and carbon dioxide gases around the fruit, which promotes ripening.
Climacteric fruits are able to continue ripening after being picked, a process accelerated by ethylene gas. Non-climacteric fruits can ripen only on the plant and thus have a short shelf life if harvested when they are ripe.
Iodine (I) can be used to determine whether fruit is ripening or rotting by showing whether the starch in the fruit has turned into sugar. For example, a drop of iodine on a slightly rotten part (not the skin) of an apple will turn a dark-blue or black color, since starch is present. If the iodine is applied and takes 2–3 seconds to turn blue/black, then the process has begun but is not yet complete. If the iodine stays yellow, then most of the starch has been converted to sugar.
Fruit ripening is divided into stages[specify], one of which is breaker stage.
- Adel A. Kader (2002). Postharvest Technology of Horticultural Crops. University of California. p. 157. ISBN [[Special:BookSources/1-879906-51-5|1-879906-51-5[[Category:Articles with invalid ISBNs]]]] Check
- Per, Hüseyin; Kurtoğlu, Selim; Yağmur, Fatih; Gümüş, Hakan; Kumandaş, Sefer; Poyrazoğlu, M. Hakan (2007), "Calcium carbide poisoning via food in childhood", The Journal of Emergency Medicine 32
- "Bet on it. Your mango is ripened using carbide". DNA. May 18, 2013. Retrieved 18 May 2013.
- "The toxic truth about ripe mangoes". Indian Express. 18 May 2013. Retrieved 18 May 2013.
- Burg SP, Burg EA (March 1962). "Role of Ethylene in Fruit Ripening". Plant Physiol. 37 (2): 179–89. doi:10.1104/pp.37.2.179. PMC 549760. PMID 16655629.
- Cooking For Engineers – Table of fruits which ripen after harvest