Lime (fruit)
A lime (from French "lime", from Arabic "līma", from Persian "līmū", "lemon") is a citrus fruit, which is typically round, green in color, in diameter, and contains acidic juice vesicles. There are several species of citrus trees whose fruits are called limes, including the Key lime ("Citrus aurantiifolia"), Persian lime, Makrut lime, and desert lime. Limes are a rich source of vitamin C, are sour, and are often used to accent the flavours of foods and beverages. They are grown year-round. Plants with fruit called "limes" have diverse genetic origins; limes do not form a monophyletic group . Plants known as "lime". The difficulty in identifying exactly which species of fruit are called lime in different parts of the English-speaking world (and the same problem applies to synonyms in other European languages) is increased by the botanical complexity of the citrus genus itself, to which the majority of limes belong. Species of this genus hybridise readily, and it is only recently that genetic studies have started to shed light on the structure of the genus. The majority of cultivated species are in reality hybrids, produced from the citron ("Citrus medica"), the mandarin orange ("Citrus reticulata"), the pomelo  ("Citrus maxima") and in particular with many lime varieties, the micrantha ("Citrus hystrix" var. micrantha). Note that the tree species known in Britain as lime trees ("Tilia" sp.), called "linden" in other dialects of English, are broadleaf temperate plants unrelated to the citrus fruits. History. Most species and hybrids of citrus plants called "limes" have varying origins within tropical Southeast Asia and South Asia. They were spread throughout the world via migration and trade. The makrut lime, in particular, was one of the earliest citrus fruits introduced to other parts of the world by humans. They were spread into Micronesia  and Polynesia via the Austronesian expansion (c. 3000–1500 BCE). They were also later spread into Middle East, and the Mediterranean region via the spice trade and the incense trade routes from as early as ~1200 BCE. To prevent scurvy during the 19th century, British sailors were issued a daily allowance of citrus, such as lemon, and later switched to lime. The use of citrus was initially a closely guarded military secret, as scurvy was a common scourge of various national navies, and the ability to remain at sea for lengthy periods without contracting the disorder was a huge benefit for  the military. British sailors thus acquired the nickname "Limey" because of their use of limes. Production. In 2018, world production of limes (combined with lemons for reporting) was 19.4 million tonnes. The top producers – India, Mexico, China, Argentina, Brazil, and Turkey – collectively accounted for 65% of global production (table). Uses. Limes have higher contents of sugars and acids than lemons do. Lime juice may be squeezed from fresh limes, or purchased in bottles in both unsweetened and sweetened varieties. Lime juice is used to make limeade, and as an ingredient (typically as sour mix) in many cocktails. Lime pickles are  an integral part of Indian cuisine, especially in South India. In Kerala, the Onam Sadhya usually includes either lemon pickle or lime pickle. Other Indian preparations of limes include sweetened lime pickle, salted pickle, and lime chutney. In cooking, lime is valued both for the acidity of its juice and the floral aroma of its zest. It is a common ingredient in authentic Mexican, Vietnamese and Thai dishes. Lime soup is a traditional dish from the Mexican state of Yucatan. It is also used for its pickling properties in ceviche. Some guacamole recipes call for lime juice. The use of  dried limes (called black lime or "limoo") as a flavouring is typical of Persian cuisine, Iraqi cuisine, as well as in Eastern Arabian cuisine "baharat" (a spice mixture that is also called "kabsa" or "kebsa"). Key lime gives the character flavoring to the American dessert known as Key lime pie. In Australia, desert lime is used for making marmalade. Lime is an ingredient in several highball cocktails, often based on gin, such as gin and tonic, the gimlet and the Rickey. Freshly squeezed lime juice is also considered a key ingredient in margaritas, although sometimes lemon juice is substituted. It  is also found in many rum cocktails such as the Daiquiri, and other tropical drinks. Lime extracts and lime essential oils are frequently used in perfumes, cleaning products, and aromatherapy. Nutrition and phytochemicals. Raw limes are 88% water, 10% carbohydrates and less than 1% each of fat and protein (table). Only vitamin C content at 35% of the Daily Value (DV) per 100 g serving is significant for nutrition, with other nutrients present in low DV amounts (table). Lime juice contains slightly less citric acid than lemon juice (about 47 g/l), nearly twice the citric acid of grapefruit juice , and about five times the amount of citric acid found in orange juice. Lime pulp and peel contain diverse phytochemicals, including polyphenols and terpenes, many of which are under basic research for their potential properties in humans. Toxicity. Contact with lime peel or lime juice followed by exposure to ultraviolet light may lead to phytophotodermatitis, which is sometimes called margarita photodermatitis or lime disease (not to be confused with Lyme disease). Bartenders handling limes and other citrus fruits while preparing cocktails may develop phytophotodermatitis. A class of organic chemical compounds called furanocoumarins are reported to cause phytophotodermatitis in humans. Limes  contain numerous furanocoumarin compounds, including limettin (also called citropten), bergapten, isopimpinellin, xanthotoxin (also called methoxsalen), and psoralen. Bergapten appears to be the primary furanocoumarin compound responsible for lime-induced phytophotodermatitis. Lime peel contains higher concentrations of furanocoumarins than lime pulp (by one or two orders of magnitude), and so lime peels are considerably more phototoxic than lime pulp. Persian limes appear to be more phototoxic than Key limes.