Limunska trava

Lemongrass oil is produced commercially from species such as Cymbopogon citratus and Cymbopogon flexuosus. Cymbopogon citratus, commonly known as West Indian lemon grass, is a tropical plant native to South Asia and Maritime Southeast Asia. Cymbopogon flexuosus, also called Cochin grass, East-Indian lemon grass or Malabar grass, is a perennial grass native to India, Sri Lanka, Burma and Thailand. Both belong to the grass family, Poaceae, and to the genus Cymbopogon, which currently numbers 52 species. C. citratus has simple, bluish-green, linear leaves with entire margins and parallel venation, and its blades tend to be 18 to 36 inches long. It can be grown in warmer temperate regions but is not hardy to frost, and it is often sold in stem form.

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Chemistry

Lemongrass oil contains 65-85% citral, in addition to myrcene, citronellal, citronellol, linalool and geraniol. Citral (CAS 5392-40-5) is an acyclic monoterpene aldehyde. It is a collective term for two geometric isomers: geranial, the E-isomer, and neral, the Z-isomer. In lemongrass oil, geranial is often 30-45% and neral often 25-35%. Beta-myrcene is commonly 5-15% and geraniol 2-10%. Composition varies by species or chemotype, geographic origin, harvest conditions and extraction method. Citral has the molecular formula C₁₀H₁₆O and a molecular weight of 152.23, and its systematic name is 3,7-dimethylocta-2,6-dienal. As a monoterpene, citral is made of two isoprene units. Geranial is also called trans-citral, α-citral or citral A, and neral is also called cis-citral, β-citral or citral B. Besides citral, the oil holds geranyl acetate, limonene, beta-caryophyllene and camphene, and citronellal can reach 5-15% in some chemotypes. In commercial grades citral is often above 70% of the oil. Lemongrass oil has a density of about 0.9 g/ml and is miscible with organic solvents, mineral oil and ether.

Uses

Lemongrass oil is used for control of fungal infections and for general insect control. It is applied against post-harvest storage diseases of stored crops and against pests including mosquitoes, leafrollers and loopers, and it is available as ready-to-use sprays and liquid concentrates. Its mode of action is a non-toxic repellency. Some Cymbopogon species, particularly C. citratus, are commonly cultivated as culinary and medicinal herbs because their scent resembles that of lemons. The fragrant leaves of C. citratus are traditionally used in cooking, and the dried leaves can be brewed into a tea. The leaves of C. citratus have also been used in traditional medicine and are often found in herbal supplements and teas. The related citronella grasses, Cymbopogon nardus and Cymbopogon winterianus, give citronella oil, a separate oil used in soaps, insect sprays, candles and aromatherapy. Lemongrass essential oil has been declared generally recognized as safe in food by the United States Food and Drug Administration. Citral is commonly used as a food additive ingredient.