Citral is an acyclic monoterpene aldehyde. Being amonoterpene, it is made of twoisoprene units. Citral is a collective term which covers two geometric isomers that have their own separate names; theE-isomer is namedgeranial (trans-citral; α-citral[2]) or citral A. TheZ-isomer is namedneral (cis-citral; β-citral[2]) or citral B. Thesestereoisomers occur as a mixture, often not in equal proportions; e.g. in essential oil ofAustralian ginger, the neral to geranial ratio is 0.61.[3]
Further, in the lipid fraction (essential oil) of Australian ginger (51–71%)[3] Of the many sources of citral, the Australian myrtaceous tree, lemon myrtle,Backhousia citriodora F. Muell. (of the familyMyrtaceae), is considered superior.[7]
Citral has a strong lemon (citrus) scent and is used as anaroma compound in perfumery. It is used to fortify lemon oil. (Nerol, another perfumery compound, has a less intense but sweeter lemon note.) The aldehydes citronellal and citral are considered key components responsible for the lemon note with citral preferred.[7]
^Robacker, D.C.; Hendry, L.B. (1977). "Neral and geranial: components of the sex pheromone of the parasitic wasp, Itoplectis conquisitor".Journal of Chemical Ecology.3 (5):563–577.doi:10.1007/BF00989077.S2CID11568355.
^Dubey, N. K.; Takeya, Koichi; Itokawa, Hideji (1997). "Citral: A cytotoxic principle isolated from the essential oil of Cymbopogon citratus against P388 leukaemia cells".Current Science.73 (1):22–24.JSTOR24098141.
