The Lemon (Citrus limon) is a species of small evergreen tree in the flowering plant family Rutaceae. Believed to be native to South Asia, the true home of the lemon is unknown, although some have linked it to Northeast India (Assam). The Citron (Citrus medica) was the first of the family of citrus fruit to reach the Mediterranean [1]. The Citron spread West probably through Persia, where remains of a Citron were found in a 2,500-year-old Persian garden near Jerusalem, and through the Southern Levant (modern Israel, Jordan, Lebanon, southern Syria and Cyprus). During the 3rd- and 2nd-centuries BC, it spread to the western Mediterranean.
The earliest Citron remains found in a Roman context were discovered in Rome's Forum dating between the late 1st-century BC and the early 1st-century AD. Citron seeds and pollen were also found in gardens owned by the wealthy in Rome and the area around Mount Vesuvius. It took another 400 years for the lemon (Citrus limon) to reach the Mediterranean area and is supposed to have been introduced into southern Italy in AD 200. Citrons and lemons were not widely cultivated nor it seems did the Romans use lemons in cooking. However, it does seem that the wealthy Roman elite prized the trees for their decorative appeal in gardens, pleasant odour, healing qualities, symbolic use and rarity.
Around AD 700 Citrus limon trees were being cultivated in Persia, Iraq and Egypt [2][3], but it was not until the 10th-century that the lemon was first recorded in literature in an Arabic treatise on farming. Like the Romans lemon trees were also used as an ornamental plant in early Islamic gardens. Between AD 1000 and 1150 Arab traders distributed the lemon round the Mediterranean region [4], and 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 carried lemon seeds to Hispaniola. Subsequently, the Spanish conquest throughout the New World helped spread lemon seeds further still. Eventually, they were being grown in California in the years 1751-1768, and increasingly planted in Florida and California during the 19th-century.
The ellipsoidal yellow fruit of the lemon tree was initially used as an ornamental plant and in medicine [2]. It was, for example, prized for its medicinal virtues in the palace of the Sultan of Egypt and Syria in the years between 1174 and 1193. Scroll forward to the 18th-century and scurvy [5] was increasingly becoming a problem for the health of sailors on long sea voyages where they had limited access to fresh fruit. Although the connection between the disease and vitamin C was not fully understood, Scottish doctor, James Lind FRSE FRCPE (4 October 1716 – 13 July 1794), developed the theory that citrus fruits cured scurvy. A pioneer of naval hygiene in the Royal Navy, Lind conducted one of the first ever clinical trials on seamen suffering from scurvy to show the addition of lemon juice to their diets had a positive benefit to health.
Today lemons are used throughout the world for both culinary and non-culinary purposes. Although the pulp and rind are used in cooking and baking, it is the lemon's juice that is used for primarily both for culinary and cleaning purposes [2]. The juice is about 5% to 6% citric acid, with a pH of around 2.2, which gives a distinctively sour taste and makes it a key ingredient in drinks and foods.
An ingredient in lemonade, soft drinks, and cocktails, lemon juice is also used in marinades for fish where it neutralizes amino acids to delay the onset of decay. In meat, the acidic nature acts to partially breaks down tough collagen fibres and thus tenderise it. Lemon juice is also used as a short-term preservative on those foods that tend to oxidize and turn brown after being sliced, such as apples, bananas, and avocados. Known as enzymatic browning, the juice's acidity acts to denature the enzymes that cause the colour change.
Whole lemons are used to make marmalade, lemon curd and lemon liqueur, while 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 flavour to baked goods, puddings, rice, and other dishes. In Morocco, lemons are preserved in jars or barrels of salt which penetrates the peel and rind, softening them, and curing them so that they last almost indefinitely. The preserved lemon is subsequently used in a wide variety of recipes.
Endnotes:
1. Being the first is why the whole group of fruits are named after the Citron. ▲
2. Morton, J., (1987), 'Lemon' in 'Fruits of warm climates', Miami, p. 160–168, Available online (accessed September 2nd, 2021). ▲
3. The lemon reached China sometime between AD 760 and 1297. ▲
4. Lemons did not arrive in Sicily before AD 1000 for example. ▲
5. Scurvy is a disease resulting from a deficiency of vitamin C (ascorbic acid). It takes at least a month of little to no vitamin C in the diet before symptoms occur. Early symptoms include weakness, feeling tired and sore arms and legs. Without treatment, decreased red blood cells, gum disease, changes to hair, and bleeding from the skin may occur. As scurvy worsens there can be poor wound healing, personality changes, and finally death from infection or bleeding. ▲