Citral is an acyclic monoterpene aldehyde. Being a

monoterpene Monoterpenes are a class of terpenes that consist of two isoprene units and have the molecular formula C10H16. Monoterpenes may be linear (acyclic) or contain rings (monocyclic and bicyclic). Modified terpenes, such as those containing oxygen func ...

, 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) or citral A. The ''Z''-isomer is named neral (''cis''-citral; β-citral) 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.

Natural Occurrence

Citral is present in the volatile oils of several plants: 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 Myrtaceae (), the myrtle family, is a family of dicotyledonous plants placed within the order Myrtales. Myrtle, pōhutukawa, bay rum tree, clove, guava, acca (feijoa), allspice, and eucalyptus are some notable members of this group. All ...

), is considered superior.

Uses

Citral is a precursor in the industrial production of

vitamin A Vitamin A is a fat-soluble vitamin that is an essential nutrient. The term "vitamin A" encompasses a group of chemically related organic compounds that includes retinol, retinyl esters, and several provitamin (precursor) carotenoids, most not ...

vitamin E Vitamin E is a group of eight compounds related in molecular structure that includes four tocopherols and four tocotrienols. The tocopherols function as fat-soluble antioxidants which may help protect cell membranes from reactive oxygen speci ...

vitamin K Vitamin K is a family of structurally similar, fat-soluble vitamers found in foods and marketed as dietary supplements. The human body requires vitamin K for post-translational modification, post-synthesis modification of certain proteins ...

. Citral is also precursor to lycopene, ionone and methylionone.

Fragrances

Citral has a strong lemon (citrus) scent and is used as an

aroma compound An aroma compound, also known as an odorant, aroma, fragrance, flavoring or flavor, is a chemical compound that has a smell or odor. For an individual chemical or class of chemical compounds to impart a smell or fragrance, it must be sufficien ...

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. It also has pheromonal effects in acari and

insects Insects (from Latin ') are hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs of jointed ...

. The herb '' Cymbopogon citratus'' has shown promising insecticidal and antifungal activity against storage pests.

Food additive

Citral is commonly used as a food additive ingredient. It has been tested (2016) in vitro against the food-borne pathogen '' Cronobacter sakazakii''.

References

External links