Chemistry:Citral
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; α-citral[1]) or citral A. The Z-isomer is named neral (cis-citral; β-citral[1]) or citral B. These stereoisomers occur as a mixture, often not in equal proportions; e.g. in essential oil of Australian ginger, the neral to geranial ratio is 0.61.[2]
Natural Occurrence
Citral is present in the volatile oils of several plants:[3][4][5]
- 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%)
- orange
Of the many sources of citral, the Australian tree Backhousia citriodora (family Myrtaceae) is considered superior.[6]
Uses
Citral is a precursor in the industrial production of vitamin A, vitamin E, vitamin K.
Citral is also precursor to lycopene, ionone and methylionone.
Fragrances
Citral has a strong lemon (citrus) scent and is used as an aroma compound in perfumery. It is used to fortify lemon oil presenting as sharp, lemon, sweet, fresh, juicy, lemon peel, tart, and green.[7] (Neral, the (E)-isomer, has a less sweeter citrus, lemon, lemon peel note,[8] whilst Geranial, the (E)-isomer is described as citrus, lemon.[9]) The aldehydes citronellal and citral are considered key components responsible for the lemon note with citral preferred.[6]
It also has pheromonal effects in acari and insects.[10][11]
The herb Cymbopogon citratus has shown promising insecticidal and antifungal activity against storage pests.[12]
Food additive
Citral is commonly used as a food additive ingredient.[13]
It has been tested (2016) in vitro against the food-borne pathogen Cronobacter sakazakii.[14]
See also
- Citronellal
- Geraniol
- Limonene
- Nerol
- Vaporizer
References
- ↑ 1.0 1.1 Waghulde, S.; Parmar, P.; Mule, J.; Pashte, D.; Patil, B.; Modhale, N.; Gorde, N.; Kharche, A. et al. (2020). "Lead Finding from Plant Cymbopogon Citratus with Immunomodulator Potentials through in Silico Methods" (in en). Chemistry Proceedings 3 (1): 77. doi:10.3390/ecsoc-24-08302. ISSN 2673-4583.
- ↑ Zachariah, T. J.; Parthasarathy, V. A.; Chempakam, B. (2008). Chemistry of spices. Wallingford: CABI. p. 76. ISBN 978-1-84593-405-7. OCLC 1120264204.
- ↑ Fenaroli, G.; Furia, T.E.; Bellanca, N.. Handbook of Flavor Ingredients. ISBN 0-87819-532-7.
- ↑ Lawless, J. (2 November 1995). The Illustrated Encyclopedia of Essential Oils. Element. ISBN 1-85230-661-0.
- ↑ "The Aromatic Plant Project". http://www.aromaticplantproject.com/articles_archive/lemon_citrus_scented_oils.html.
- ↑ 6.0 6.1 Southwell, Ian (9 July 2021). "Backhousia citriodora F. Muell. (Lemon Myrtle), an Unrivalled Source of Citral". Foods 10 (7): 1596. doi:10.3390/foods10071596. PMID 34359465.
- ↑ "Citral". Scents and Flavors. https://scentsandflavors.com/database/9dbb4f57-a867-46d1-accd-5b189f2c162d.
- ↑ "(Z)-Citral". Scents and Flavors. https://scentsandflavors.com/database/9dbb5566-2a74-4c75-b2fa-b7ed1efced78.
- ↑ "(E)-Citral". Scents and Flavors. https://scentsandflavors.com/database/9dbb5196-35f5-402b-be6c-537bebaf8398.
- ↑ Kuwahara, Yasumasa; Suzuki, Hiroshi; Matsumoto, Katsuhiko; Wada, Yoshitake (1983). "Pheromone Study on Acarid Mites. XI. Function of Mite Body as Geometrical Isomerization and Reduction of Citral (the Alarm Pheromone)". Applied Entomology and Zoology 18 (1): 30–39. doi:10.1303/aez.18.30.
- ↑ 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.
- ↑ 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.
- ↑ 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 et al. (14 July 2016). "Antimicrobial Activity and Possible Mechanism of Action of Citral against Cronobacter sakazakii". PLOS ONE 11 (7). doi:10.1371/journal.pone.0159006. PMID 27415761. Bibcode: 2016PLoSO..1159006S.
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