3D model (JSmol)
CompTox Dashboard (EPA)
|Molar mass||152.24 g/mol|
|Appearance||Pale yellow liquid|
|Boiling point||229 °C (444 °F; 502 K)|
|Vapor pressure||0.22 mmHg (20 °C)|
|P261, P264, P272, P280, P302+P352, P321, P332+P313, P333+P313, P362, P363, P501|
|NFPA 704 (fire diamond)|
|Flash point||91 °C (196 °F; 364 K)|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
(what is ?)
Citral is an acyclic monoterpene aldehyde. Being a monoterpene, it is made of two isoprene units. Citral is a collective term which covers two geometric isomers that have their own separate names; the E-isomer is named geranial (trans-citral) or citral A. The Z-isomer is named neral (cis-citral) or citral B. These stereoisomers occur as a mixture, not necessarily racemic; e.g. in essential oil of Australian ginger, the neral to geranial ratio is 0.61.
Citral is present in the volatile oils of several plants, including lemon myrtle (90–98%), Litsea citrata (90%), Litsea cubeba (70–85%), lemongrass (65–85%), lemon tea-tree (70–80%), Ocimum gratissimum (66.5%), Lindera citriodora (about 65%), Calypranthes parriculata (about 62%), petitgrain (36%), lemon verbena (30–35%), lemon ironbark (26%), lemon balm (11%), lime (6–9%), lemon (2–5%), and orange. Further, in the lipid fraction (essential oil) of Australian ginger (51–71%) Of the many sources of citral, the Australian myrtaceous tree, lemon myrtle, Backhousia citriodora F. Muell. (of the family Myrtaceae), is considered superior.
Citral has a strong lemon (citrus) scent and is used as an aroma 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.
Citral is commonly used as a food additive ingredient.
Two studies showed 1–1.7% of people to be allergic to citral, with allergies frequently reported. Citral on its own is strongly sensitizing to allergies; the International Fragrance Association recommends that citral only be used in association with substances that prevent a sensitizing effect. Citral has been extensively tested, with no known genotoxicity or carcinogenic effect.
- Citral, The Merck Index, 12th Edition.
- Zachariah, T. J. Chemistry of Spices. p. 76.[ISBN missing]
- Fenaroli, G.; Furia, T.E.; Bellanca, N. Handbook of Flavor Ingredients. ISBN 0-87819-532-7.
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- Southwell, Ian (9 July 2021). "Backhousia citriodora F. Muell. (Lemon Myrtle), an Unrivalled Source of Citral". Foods. 10 (7): 1596. doi:10.3390/foods10071596. PMC 8305781. PMID 34359465.
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- Liao, Pei-Chun; Yang, Tsung-Shi; Chou, Ju-Ching; Chen, Jie; Lee, Shu-Ching; Kuo, Yueh-Hsiung; Ho, Chen-Lung; Chao, Louis Kuo-Ping (1 December 2015). "Anti-inflammatory activity of neral and geranial isolated from fruits of Litsea cubeba Lour". Journal of Functional Foods. 19: 248–258. doi:10.1016/j.jff.2015.09.034.
- Shi, Chao; Song, Kaikuo; Zhang, Xiaorong; Sun, Yi; Sui, Yue; Chen, Yifei; Jia, Zhenyu; Sun, Huihui; Sun, Zheng; Xia, Xiaodong (14 July 2016). "Antimicrobial Activity and Possible Mechanism of Action of Citral against Cronobacter sakazakii". PLOS ONE. 11 (7): e0159006. Bibcode:2016PLoSO..1159006S. doi:10.1371/journal.pone.0159006. PMC 4945043. PMID 27415761.
- Onawunmi, Grace O. (September 1989). "Evaluation of the antimicrobial activity of citral". Letters in Applied Microbiology. 9 (3): 105–108. doi:10.1111/j.1472-765X.1989.tb00301.x. S2CID 84751250.
- Andersen, Dorthe N.; Holmberg, Rikke D.; Larsen, Jette R.; Søborg, Inge; Cohr, Karl-Heinz (2006). Survey and health assessment of chemical substances in massage oils (PDF). Survey of Chemical Substances in Consumer Products, No. 78. Danish Toxicology Centre.