Beautiful Bananas - a Popular and High Quality Fruit

Although it looks like a palm tree, it is a perennial herb which grows a new shoot every year. The trunk is composed of a large number of overlapping leaf bases wrapped tightly together to form a fairly rigid structure. The growing point emerges from the apex of these leaves and eventually produces flowers which develop fruits in double rows known as "hands". The familiar banana fruit is seedless, owing to its relentless cultivation from ancestral wild bananas over many years.

The Origins of the Banana

Edible bananas go back many centuries, and they were known to the Greeks in the fourth century BC. Prior to this, wild bananas, or "monkey bananas" of Malaysia were probably the forerunner of the edible variety, which soon gained a reputation as a worthy source of energy and inspiration, according to the writings of the scholar and botanist Theophrastus (371 - 287 BC). Bananas found their way to China by AD 200, and into Africa by the end of the first millennium, from where Portuguese sailors eventually transported them to the Canary Islands - still an important growing region. It was the Bishop of Panama who took some banana roots to America in 1516, but the Spaniards of Central America confused bananas with the plane tree which gave inedible plantains (or cooking bananas) their current name. Thereafter, during the 19th century, bananas were shipped to Europe, where they were regarded as an expensive luxury until imports from the Caribbean started to arrive in bulk in the 1870s. These fruits were superior to the Canary produce, travelling well and costing less. The "Banana Republics" of Central America had cornered the market and made the banana affordable.

Why are Bananas Yellow?

Bananas grown for export can be picked while still green, because they continue to ripen after picking. The inedible starch of the unripe banana slowly changes to sucrose, fructose and glucose which produce a sweeter taste. The pigments in the skin also change from green (chloropyhll) to yellow (carotene and xanthophyll) to indicate to passing animals that the seeds (if there were any) could be accessed for dispersal by eating the ripe fruit. The ripening process involves the production of ethylene gas by the cells of the banana skin. This inflammable gas, with a sickly sweet smell, is encountered as a constituent and by-product of crude oil distillation, so the appearance of this molecule in different chemical and biological contexts is quite striking. So powerful is the ethylene production that avocados and tomatoes will ripen if left in the same container as unripe bananas.

What Lies Beneath a Banana Skin?

Despite it reputation as a fattening food, a large ripe banana weighing 150g contains around 150kcals, rather more than the equivalent weight of french fries (420kcals). In addition, the flesh contains approximately:

• 2g of protein
• 0.5g of fat
• 35g of carbohydrates, mostly soluble sugars - when ripe
• 2g of fibre
• 9mg of calcium
• 50mg of magnesium
• 600mg of potassium
• 42mg of phosphorus
• significant amounts of folic acid, vitamins A (as beta carotene), E and C.

References:

1. Davidson A. The Penguin Companion to Food. Penguin Books.
2. Food Standards Agency. Manual of Nutrition. HMSO London.