Banana is the common name for herbaceous plants of the genus Musa and for the fruit they produce. Bananas come in a variety of sizes and colors when ripe, including yellow, purple, and red. In popular culture and commerce, “banana” usually refers to soft, sweet “dessert” bananas. By contrast, Musa cultivars with firmer, starchier fruit are called plantains. Many varieties of bananas are perennial. Refer to the Musa article for a list of the varieties of bananas and plantains.
They are native to tropical Southeast Asia, and are likely to have been first domesticated in Papua New Guinea. Today, they are cultivated throughout the tropics. They are grown in at least 107 countries, primarily for their fruit, and to a lesser extent to make fiber and as ornamental plants.
Although fruit of wild species have large, hard seeds, virtually all culinary bananas are “seedless”, have only tiny seeds. Bananas are classified either as dessert bananas (meaning they are yellow and fully ripe when eaten) or as green cooking bananas.
Almost all export bananas are of the dessert types; however, only about 10–15% of production is for export. The United States and European Union are the dominant importers.
Bananas are naturally slightly radioactive, more so than most other fruits, because of their high potassium content, and the small amounts of the isotope potassium-40 found in naturally occurring potassium. Proponents of nuclear power sometimes refer to the banana equivalent dose of radiation to support their arguments. Banana shipments often set off the radiation monitors installed at US ports to detect illegal shipments of radiologic materials.
Food and cooking
Bananas are the staple starch of many tropical populations. Depending upon cultivar and ripeness, the flesh can vary in taste from starchy to sweet, and texture from firm to mushy. Both skin and inner part can be eaten raw or cooked. Bananas’ flavor is due, amongst other chemicals, to isoamyl acetate which is one of the main constituents of banana oil.
During the ripening process, bananas produce a plant hormone called ethylene, which indirectly affects the flavor. Among other things, ethylene stimulates the formation of amylase, an enzyme that breaks down starch into sugar, influencing the taste of bananas. The greener, less ripe bananas contain higher levels of starch and, consequently, have a “starchier” taste. On the other hand, yellow bananas taste sweeter due to higher sugar concentrations. Furthermore, ethylene signals the production of pectinase, an enzyme which breaks down the pectin between the cells of the banana, causing the banana to soften as it ripens.
Bananas are eaten deep fried, baked in their skin in a split bamboo, or steamed in glutinous rice wrapped in a banana leaf. Bananas can be made into jam. Banana pancakes are popular amongst backpackers and other travelers in South Asia and Southeast Asia. This has elicited the expression Banana Pancake Trail for those places in Asia that cater to this group of travelers. Banana chips are a snack produced from sliced dehydrated or fried banana or plantain, which have a dark brown color and an intense banana taste. Dried bananas are also ground to make banana flour. Extracting juice is difficult, because when a banana is compressed, it simply turns to pulp. Bananas fried with batter is a popular dessert in Malaysia, Singapore, and Indonesia. A similar dish is known in the United States as banana fritters.
Plantains are used in various stews and curries or cooked, baked or mashed in much the same way as potatoes.
Seeded bananas (Musa balbisiana), the forerunner of the common domesticated banana, are sold in markets in Indonesia.
While the original bananas contained large seeds, triploid cultivars with tiny seeds are preferred for human raw fruit consumption. These are propagated asexually from offshoots. The plant is allowed to produce 2 shoots at a time; a larger one for immediate fruiting and a smaller “sucker” or “follower” to produce fruit in 6–8 months. The life of a banana plantation is 25 years or longer, during which time the individual stools or planting sites may move slightly from their original positions as lateral rhizome formation dictates.
Cultivated bananas are parthenocarpic, which makes them sterile and unable to produce viable seeds. Lacking seeds, propagation typically involves removing and transplanting part of the underground stem (called a corm). Usually this is done by carefully removing a sucker (a vertical shoot that develops from the base of the banana pseudostem) with some roots intact. However, small sympodial corms, representing not yet elongated suckers, are easier to transplant and can be left out of the ground for up to 2 weeks; they require minimal care and can be shipped in bulk.
It is not necessary to include the corm or root structure to propagate bananas; severed suckers without root material can be propagated in damp sand, although this takes somewhat longer.
In some countries, commercial propagation occurs by means of tissue culture. This method is preferred since it ensures disease-free planting material. When using vegetative parts such as suckers for propagation, there is a risk of transmitting diseases (especially the devastating Panama disease).
As a non-seasonal crop, bananas are available fresh year-round.
In global commerce, by far the most important cultivar is ‘Cavendish’, which accounts for the majority of banana exports. The Cavendish gained popularity in the 1950s after the previous mass-produced cultivar, Gros Michel, became commercially unviable due to Panama disease, a fungus which attacks the roots of the banana plant.
Ease of transport and shelf life rather than superior taste make the Cavendish the main export banana.
Even though it is no longer viable for large scale cultivation, Gros Michel is not extinct and is still grown in areas where Panama disease is not found. Likewise, Cavendish is in no danger of extinction, but it may leave supermarket shelves if disease makes it impossible to supply the global market. It is unclear if any existing cultivar can replace Cavendish, so various hybridisation and genetic engineering programs are attempting to create a disease-resistant, mass-market banana.
Export bananas are picked green, and ripen in special rooms upon arrival in the destination country. These rooms are air-tight and filled with ethylene gas to induce ripening. The vivid yellow color normally associated with supermarket bananas is in fact a side effect of the artificial ripening process. Flavor and texture are also affected by ripening temperature. Bananas are refrigerated to between 13.5 and 15 °C (56 and 59 °F) during transport. At lower temperatures, ripening permanently stalls, and turns the bananas gray as cell walls break down. The skin of ripe bananas quickly blackens in the 4 °C (39 °F) environment of a domestic refrigerator, although the fruit inside remains unaffected.
“Tree-ripened” Cavendish bananas have a greenish-yellow appearance which changes to a brownish-yellow as they ripen further. Although both flavor and texture of tree-ripened bananas is generally regarded as superior to any type of green-picked fruit, this reduces shelf life to only 7–10 days.
Ripened bananas fluoresce in blue when exposed to UV light.
Bananas can be ordered by the retailer “ungassed”, and may show up at the supermarket fully green. “Guineo Verde”, or green bananas that have not been gassed will never fully ripen before becoming rotten. Instead of fresh eating, these bananas are best suited to cooking, as seen in Mexican culinary dishes.
A 2008 study reported that ripe bananas fluoresce when exposed to ultraviolet light. This property is attributed to the degradation of chlorophyll leading to the accumulation of a fluorescent product in the skin of the fruit. The chlorophyll breakdown product is stabilized by a propionate ester group. Banana-plant leaves also fluoresce in the same way. Green bananas do not fluoresce. The study suggested that this allows animals which can see light in the ultraviolet spectrum (tetrachromats and pentachromats) to more easily detect ripened bananas.