Science

Citral: Behind A Component of Lemongrass Oil

Mell Green
Written by Mell Green

Citral is composed of a pair of naturally occurring phytochemicals, geranial and neral, which are isomers of one another. They are sourced from a number of plants, some of the most common ones being lemongrass, lemon myrtle, lemon fruit, and orange trees. Because its odor strongly resembles the smell of citrus fruit, citral is used in a range of commercial products including personal care products, perfumes and colognes, suntan products as well flavorings for sweets and soft drinks. Its name, ‘citral,’ is a clear giveaway of its fruity origins. But just what kind of process does it take to obtain citral?

Table 1. The chemical constituents of citral, geranial and neral, are the aldehyde equivalents of the terpenes geraniol and nerol, which are also commonly found in cannabis plants.


This highly concentrated citral oil not only acts as an antimicrobial (a substance that suppresses the growth of bacteria,  fungi, and other hazzardous microbes), but it was found in a study on rabbits to play a vital role in the production of vitamin A, [3] essential for development as well as supporting effective vision and a strong immune system. [4] However, it’s important to note that you should never use pure oils on the skin or internally. Citral tends to be used in relatively small quantities whether consumed or coming into contact with the skin. Flavorings, for good example, commonly contain no more than 40 parts per million (ppm) of the mixture as isolated citral is a highly potent irritant. [5] Without diluting the concentration of this compound, exposure may include symptoms of contact dermatitis and can also increase susceptibility to allergic reactions. In any case, if you have noticed that certain terpene-containing or citrus products have been causing skin issues, you may want to consider testing yourself for a citral allergy.As we mentioned earlier, citral is a blend of not one, but two compounds. One common way to obtain and purify citral is by isolating lemongrass oil (which is obtained from lemon grass) using steam distillation. [1] To do so, lemongrass is put into a distillation flask and secured tightly to prevent the vapors and oils from leaking out. Steam is then injected into it, which extracts the essential oil from the plant material. The lemongrass oil, as well as the vapors, pass through a condenser, liquify into two separate layers, and are easily separated. [2]

Resources

  1. Rao, H.J., et al. “Isolation Of Citral From Lemongrass Oil Using Steam Distillation: Statistical Optimization By Response Surface Methodology”. Int. J. Chem. Sci. 2015; 13(3): 1305-1314. Times cited = N/A, Journal impact factor 1.600
  2. Boukhatem, M. N., et al. “Lemongrass (Cymbopogon citratus) essential oil as a potent anti-inflammatory and antifungal drugs”. Libyan J Med. 2014; 9: 25431. Times cited = 68, Journal impact factor = 1.656
  3. Rodger, F.C., et al. “The Effect of Citral and Vitamin A: On the Intraocular Dynamics of Rabbits”. Am J Ophth. 1960; 50(2): 309-313. Times cited = 7, Journal impact factor = 4.795
  4. Gilbert, Clare. “What is vitamin A and why do we need it?”. Comm Eye Health. 2013; 26(84): 65. Times cited = 5, Journal impact factor = N/A
  5. Cardullo, A. C., Ruszkowski, A. M., and DeLeo, V. A. “Allergic contact dermatitis resulting from sensitivity to citrus peel, Geraniol, and Citral”. J Am Acad Dermatol. 1989; 21(2):  395–397. Times cited = 63, Journal impact factor = 6.898

Image Credit: Chemistry World

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Mell Green

Mell Green

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