The tree's ellipsoidal yellow fruit is used for culinary and non-culinary purposes throughout the world, primarily for its juice, which has both culinary and cleaning uses. The pulp and rind are also used in cooking and baking. The juice of the lemon is about 5% to 6% citric acid, with a pH of around 2.2, giving it a sour taste. The distinctive sour taste of lemon juice makes it a key ingredient in drinks and foods such as lemonade and lemon meringue pie.
Lemons entered Europe near southern Italy no later than the second century AD, during the time of Ancient Rome. However, they were not widely cultivated. They were later introduced to Persia and then to Iraq and Egypt around 700 AD. The lemon was first recorded in literature in a 10th-century Arabic treatise on farming, and was also used as an ornamental plant in early Islamic gardens. It was distributed widely throughout the Arab world and the Mediterranean region between 1000 and 1150.
The first substantial cultivation of lemons in Europe began in Genoa in the middle of the 15th century. The lemon was later introduced to the Americas in 1493 when Christopher Columbus brought lemon seeds to Hispaniola on his voyages. Spanish conquest throughout the New World helped spread lemon seeds. It was mainly used as an ornamental plant and for medicine. In the 19th century, lemons were increasingly planted in Florida and California.
In 1747, James Lind's experiments on seamen suffering from scurvy involved adding lemon juice to their diets, though vitamin C was not yet known as an important dietary ingredient.
The origin of the word lemon may be Middle Eastern. The word draws from the Old French limon, then Italian limone, from the Arabic laym?n or l?m?n, and from the Persianl?m?n, a generic term for citrus fruit, which is a cognate of Sanskrit (nimb?, "lime").
The 'Bonnie Brae' is oblong, smooth, thin-skinned and seedless. These are mostly grown in San Diego County, USA.
The 'Eureka' grows year-round and abundantly. This is the common supermarket lemon, also known as 'Four Seasons' (Quatre Saisons) because of its ability to produce fruit and flowers together throughout the year. This variety is also available as a plant to domestic customers. There is also a pink-fleshed Eureka lemon, with a green and yellow variegated outer skin.
The 'Femminello St. Teresa', or 'Sorrento' is native to Italy. This fruit's zest is high in lemon oils. It is the variety traditionally used in the making of limoncello.
Lemon juice, rind, and peel are used in a wide variety of foods and drinks. The whole lemon is used to make marmalade, lemon curd and lemon liqueur. Lemon slices and lemon rind are used as a garnish for food and drinks. Lemon zest, the grated outer rind of the fruit, is used to add flavor to baked goods, puddings, rice, and other dishes.
In Morocco, lemons are preserved in jars or barrels of salt. The salt penetrates the peel and rind, softening them, and curing them so that they last almost indefinitely. The preserved lemon is used in a wide variety of dishes. Preserved lemons can also be found in Sicilian, Italian, Greek, and French dishes.
A major industry use of the peel is manufacturing of pectin - a polysaccharide used as a gelling agent, thickening agent and stabilizer in food and other products.
Lemon oil is extracted from oil-containing cells in the skin. A machine breaks up the cells, and uses a water spray to flush off the oil. The oil/water mixture is then filtered and separated by centrifugation.
The leaves of the lemon tree are used to make a tea and for preparing cooked meats and seafoods.
The juice of the lemon may be used for cleaning. A halved lemon dipped in salt or baking powder is used to brighten copper cookware. The acid dissolves the tarnish, and the abrasives assist the cleaning. As a kitchen cleaning agent the juice can deodorize, remove grease, bleach stains, and disinfects. The oil of the lemon's peel also has various uses. It is used as a wood cleaner and polish, where its solvent property is employed to dissolve old wax, fingerprints, and grime. Lemon oil and orange oil are also used as a nontoxic insecticide treatment.
One educational science experiment involves attaching electrodes to a lemon and using it as a battery to produce electricity. Although very low power, several lemon batteries can power a small digital watch. These experiments also work with other fruits and vegetables.
Lemons need a minimum temperature of around 7 °C (45 °F), so they are not hardy year-round in temperate climates, but become hardier as they mature. Citrus require minimal pruning by trimming overcrowded branches, with the tallest branch cut back to encourage bushy growth. Throughout summer, pinching back tips of the most vigorous growth assures more abundant canopy development. As mature plants may produce unwanted, fast-growing shoots called 'water shoots,' these are removed from the main branches at the bottom or middle of the plant.
In 2017, world production of lemons (combined with limes for reporting) was 17.2 million tonnes. The top producers – Mexico, India, China, Argentina, Brazil, and Turkey – collectively accounted for 65% of global production (table).
Many plants taste or smell similar to lemons.
Limes, another common sour citrus fruit, used similarly to lemons
Sumac fruits, were used long before lemmons where known to Europeans, also pink lemmonade was used in North America and other Rhus species were used in places where lemmons were out of reach, as in midle east where sumac is still very popular.
Meyer lemon, a cross between a citron and a mandarin/pomelo hybrid distinct from sour or sweet orange, named after Frank N. Meyer, who first introduced it to the United States in 1908. Thin-skinned and slightly less acidic than the Lisbon and Eureka lemons, Meyer lemons require more care when shipping and are not widely grown on a commercial basis. Meyer lemons often mature to a yellow-orange color. They are slightly more frost-tolerant.
Ponderosa lemon, more cold-sensitive than true lemons, the fruit are thick-skinned and very large. Genetic analysis showed it to be a complex hybrid of citron and pomelo.
^Gulsen, O.; M. L. Roose (2001). "Lemons: Diversity and Relationships with Selected Citrus Genotypes as Measured with Nuclear Genome Markers". Journal of the American Society of Horticultural Science. 126: 309-317.