Lemongrass Oil

#### Lemongrass Oil. **Lemongrass Oil **is produced from two distinctly different botanical species of **Cymbopogon**. One is a native of East India (Travancore, etc.) where it grows wild, and is now cultivated over a comparatively limited area in the western parts of India. The plant is Cymbopogon Flexuosus, and only cultivated plants are used for distillation. The other plant, **Cymbopogon**** ****Citratus**, is possibly a native of Ceylon and parts of East India, but it is now found only under cultivation. Unlike **C. Flexuosus**, the **Citratus **is widely distributed all over the world, and it has been given the somewhat confusing name "West Indian Lemon- grass". The two oils will be described under one monograph, but there will be an individual odor description. **Lemongrass Oil **is steam distilled from the fresh or partly dried leaves of the above grass; occasionally, it is water-and-steam distilled. Outside of India, the "west-Indian" grass is distilled in Africa (Kenya, Tanganyika, Belgian Congo, Angola, Equatorial Africa, Madagascar, Comoro islands, etc.), in Central America (Guatemala and Honduras), in the West Indies (Dominican Republic, Haiti, Jamaica, Puerto Rico), in South America (Argentina, Brazil, Suriname), and in Formosa, Indochina, Indonesia, Malaya, etc. It is one of the 10 largest essential oils in the world in respect to volume produced annually (about 1500 tons in 1958), although a good portion of this goes into the production of citral either for perfumery or flavor use, for the production of ionones, or for pharmaceutical use in the synthesis of vitamin A, etc. Lemongrass oil, as such, is not used very extensively in perfumes and not at all in flavors. **Lemongrass Oil **is a yellow or amber-colored, somewhat viscous liquid with a very strong, fresh- grassy lemon-type, herbaceous or tea-like odor. The oil is often turbid when it arrives from the producers, but care should be taken that it be kept dry (free from water) since it is able to keep 2 ½ or 3 % of water clearly dissolved at room temperature. This water content is definitely harmful to the citral which decomposes rapidly in the presence of water, air and daylight. The water is conveniently chilled out under stirring of the oil and it separates as a bottom liquid layer. In the Belgian Congo, the largest producer (at Obokoté in the district of Stanleyville) redistils his lemon- grass oil, and offers a water-free oil of 90—95% citral content. The foreruns from his redistillation consist of terpenes (myrcene, etc.) and methyl heptenone. They are used locally as low-cost detergent perfumes. When crude and unrectified, West Indian lemongrass oil is usually of a slightly lower citral content and it contains significant amounts of myrcene. In respect to odor, it has an earthy undertone reminiscent of Ceylon citronella oil (terpineol or borneol?), while the "East Indian" lemongrass oil smells sweeter, more distinctly citral- and lemon-like, fresh and light. It contains little or no myrcene. As mentioned before, **Lemongrass**** ****Oils**** **are mainly used as starting materials in the production of ionones, methylionones, vitamin A, or for the isolation of citral, which in turn is used either as such in perfumes or flavors, or it is processed into other perfume materials (acetals, etc.). Recently the Chinese oil of **Litsea Cubeba **(see this monograph) has presented a strong challenge to lemongrass oil with respect to citral production. The Chinese oil has been available in large quantities at about $ 0.77 per lb. but at the present moment (1960) it is not available at all in the U.S. A. and the quantities available in Europe are far from sufficient to cover the production of ionones, methylionones, etc. In recent years, the world production of ionones and in particular of the methylionones has exceeded 500 metric tons per year and may soon surpass 1000 metric tons. **Lemongrass Oil **contains about 70% citral which is the starting material for the production of ionones. In many tropical regions, the production of lemongrass oil is a by-product of the cattle raising: cattle feed being scarce, the exhaust grass from the distillation offers a good nutritive when added to molasses residues, etc. from sugar cane, etc. This also logically explains why the settlers continue to plant lemongrass in spite of the fact that it exhausts the soil to a considerable degree. The plant takes out nourishment, but it is fed back to the cattle who will return the yield in nature's great circulation of organic matter. It is conceivable therefore, that **Lemongrass**** ****Oil**** **will continue to be one of the "big 10" of our essential oils. Adulteration is not easy since the oil is purchased against analysis of its citral content, almost the only component of interest to the buyer. And synthetic citral is still too expensive to be used as a "cutting" agent in this case!