Lime is not one fruit but a grab bag of citrus hybrids
Key lime, Persian lime, makrut, finger lime and desert lime share a name but not a single botanical lineage. Most are hybrids stitched together from citron, mandarin, pomelo and occasionally micrantha, and a few so-called limes are not citrus at all. What unites them is green skin and ferocious sourness.
Lime juice holds roughly 47 grams of citric acid per litre, about double grapefruit juice and five times orange juice. The fruits are usually 3 to 6 centimetres across and are mostly picked while still green, when acidity and flavour peak, although many would turn yellow if left to ripen. Key limes are full of seeds, whereas the Persian lime, a cross between Key lime and lemon and the most widely grown kind, is nearly seedless.
Limes began in tropical Southeast Asia, especially Indonesia and southern China. Austronesian voyagers carried them to Micronesia and Polynesia between about 3000 and 1500 BCE, and the spice trade had brought them to the Middle East and Mediterranean by at least 1200 BCE. The makrut, with its bumpy aromatic skin, was one of the earliest citrus fruits to travel beyond its home range. In the 19th century British sailors ate citrus including limes to ward off scurvy, a practice kept as a military secret that nonetheless earned them the nickname limey.
Kitchens rely on the juice for margaritas, daiquiris, gimlets, ceviche and guacamole, and Key lime pie takes its character from its namesake. Persian, Iraqi and Eastern Arabian cooks dry whole limes into dark, tangy limoo for spice mixes, while Australians turn the native desert lime into marmalade. Unusually among citrus, lime oil is mostly produced by steam distillation rather than cold pressing, and it scents perfumes and cleaning products. In 2023 limes and lemons together totalled 23.6 million tonnes, with India and Mexico leading.
The peel carries a hazard. Furanocoumarins such as bergapten and psoralen make skin that has touched lime juice or rind react badly to sunlight, a burn-like rash nicknamed margarita photodermatitis. Confusingly, British lime trees lining avenues are Tilia, a genus with no connection to citrus, and the Spanish lime belongs to another family entirely.
Source: Lime (fruit)
