Ingredients
The Lemon
Citrus × limon (L.) Osbeck
The lemon, Citrus × limon, its fragrant, thick rind replete with aromatic oils, is one of the world’s most versatile fruits. From the sun-drenched citrus groves of the Mediterranean to the modern kitchen, the lemon is an indispensable treasure.
The lemon, Citrus × limon, its fragrant, thick rind replete with aromatic oils, is one of the world’s most versatile fruits. From the sun-drenched citrus groves of the Mediterranean to the modern kitchen, the lemon is an indispensable treasure.
Taxonomy
| Species | Name | Range |
|---|
Biology & Habitat
The lemon tree is a small, semi-evergreen tree or shrub that grows to a height of 3 to 6 metres. It thrives in a subtropical climate with mild winters and warm summers, and will tolerate only minimal frost.
Lemon trees are cultivated commercially in the Mediterranean region (Italy, Spain, Turkey), California, Argentina, and India. They prefer well-drained, slightly acidic soil with a pH of 5.5 to 6.5.
A remarkable characteristic of the lemon tree is its almost continuous flowering and fruiting. In favourable conditions, the tree bears flowers and fruit simultaneously throughout the year.
Morphology
The lemon tree has ovate to elliptical leaves, typically 6.5 to 10 cm long, with a finely serrated margin. When crushed, the leaves release a distinctive citrus fragrance.
The flowers are white within and pale purple without, with 4 to 5 petals. They are intensely fragrant and are pollinated by bees and other insects.
The fruit is an oval berry, distinguished by a nipple-like protuberance at its apex. The rind (flavedo) turns yellow upon ripening, is thick, and rich in essential oils stored in oil glands.
The thick rind of certain cultivars—such as the Sorrento lemon (PGI)—contains a particularly high concentration of essential oils, making them ideal for the production of limoncello, syrups, and preserves.
Physiology & Chemistry
The lemon peel is particularly rich in flavonoids, notably hesperidin and eriocitrin. These compounds possess antioxidant, anti-inflammatory, and cardiovascular-protective properties.
The essential oil in the peel consists of 60-70% d-limonene, a monoterpene with a powerful citrus aroma. Limonene has shown antibacterial, antifungal, and potential antitumour properties.
| Plant Part | Active Compounds |
|---|---|
| Peel (Flavedo) | D-limonene (60-70%), citral, linalool, hesperidin, eriocitrin |
| Juice | Citric acid, vitamin C, potassium, folic acid |
| Seed | Limonoids, fatty acids |
| Leaf | Essential oils, flavonoids |
Varieties & Cultivars
There are over 30 commercially grown lemon cultivars worldwide. The most renowned are Eureka, Lisbon, Sorrento (Femminello), and Meyer.
| Cultivar | Characteristics | Use |
|---|---|---|
| Eureka | An almost continuously bearing tree, with few seeds and a thin rind. | Most widely grown in California and Australia. |
| Lisbon | A robust, thorny tree that ripens in winter. | Popular in arid climates. |
| Femminello (Sorrento PGI) | A thick, oil-rich rind with an intense aroma. | Limoncello, syrups, preserves. |
| Meyer | A hybrid with a mandarin, sweeter and less acidic. | Fresh consumption, pastries. |
| Primofiore | The first harvest of the year (autumn), with a thick rind. | Fresh consumption, export. |
Health Effects
Lemon juice is an excellent source of vitamin C—100 ml contains approximately 50 mg of vitamin C (62% RDA). Vitamin C is essential for the synthesis of collagen, the function of the immune system, and the protection of cells from oxidative damage.
Hesperidin, the most abundant flavonoid in lemon peel, has demonstrated cardiovascular-protective effects in clinical studies: it lowers blood pressure, improves blood vessel function, and reduces inflammatory markers.
Citric acid in lemon juice increases the urinary excretion of citrate, which reduces the formation of kidney stones (particularly calcium oxalate stones).
Limonene from lemon peel has shown antitumour activity in laboratory studies. Epidemiological studies suggest a link with a reduced risk of certain types of cancer.
The lemon peel also has antimicrobial properties. An ethanol extract of lemon peel inhibits the growth of Staphylococcus aureus, Escherichia coli, and Candida albicans.
Precautions
- Lemon juice can erode tooth enamel with frequent direct contact. Rinse the mouth with water after consumption.
- Lemon peel may contain pesticide residues—it is preferable to use organic lemons for recipes in which the peel is used.
- Individuals with heartburn or gastroesophageal reflux should consume lemon juice in moderation.
Ethnobotany & History
The lemon has its origins in northeastern India, where wild forms of Citrus medica and related species have grown for thousands of years. The first written records of lemons date from the 1st century AD in Arabic and Persian texts.
The Arabs introduced the lemon to the Mediterranean region during the 10th and 11th centuries. The Crusaders brought lemons back to northern Europe in the 12th and 13th centuries.
In the Middle Ages, the lemon was regarded in Europe primarily as a medicinal plant. Medieval physicians used lemon juice as an antidote for poison and as a treatment for pestilence.
In the 18th century, the Scottish naval surgeon James Lind discovered that lemon juice could prevent scurvy—one of the first clinical trials in the history of medicine.
Italy, particularly the Amalfi Coast and the island of Sicily, became the centre of European lemon cultivation. The Sorrento lemon (Femminello Sorrentino) is today a Protected Geographical Indication (PGI).
Sources
Kew Gardens — Plants of the World Online; PFAF Plant Database; Missouri Botanical Garden; NCBI Taxonomy Browser; EMA Herbal Monographs; Wikipedia (verified).