Aroma compound

Source: Wikipedia, the free encyclopedia.
Several terms redirect here. For other uses, see Fragrance (disambiguation), Fragrant, Kentucky, and The Odorants.
Not to be confused with Aromaticity.

Fragrance bottles

An aroma compound, also known as an odorant, aroma, fragrance or flavoring, 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 sufficiently volatile for transmission via the air to the olfactory system in the upper part of the nose. As examples, various fragrant fruits have diverse aroma compounds,[1] particularly strawberries which are commercially cultivated to have appealing aromas, and contain several hundred aroma compounds.[1][2]

Generally, molecules meeting this specification have

smell, whereas fragrances affect only smell. Flavors tend to be naturally occurring, and the term fragrances may also apply to synthetic compounds, such as those used in cosmetics.[4]

Aroma compounds can naturally be found in various

fermentation.[6] Also, many of the aroma compounds play a significant role in the production of compounds used in the food service industry to flavor, improve, and generally increase the appeal of their products.[1]

An odorizer may add a detectable odor to a dangerous odorless substance, like propane, natural gas, or hydrogen, as a safety measure.

Aroma compounds classified by structure

Esters

Compound name Fragrance Natural occurrence Chemical structure
Geranyl acetate Fruity,
Floral 		Rose
Methyl formate Ethereal
Methyl acetate Sweet, nail polish
Solvent
Methyl propionate
Methyl propanoate 		Sweet, fruity, rum-like
Methyl butyrate
Methyl butanoate 		Fruity Apple
Pineapple
Ethyl acetate Sweet, solvent Wine
Ethyl butyrate
Ethyl butanoate 		Fruity Orange, Pineapple
Isoamyl acetate Fruity, Banana,
Pear
Banana plant
Pentyl butyrate
Pentyl butanoate 		Fruity Pear
Apricot
Pentyl pentanoate Fruity Apple
Octyl acetate Fruity Orange
Benzyl acetate Fruity, Strawberry
Strawberries
Methyl anthranilate Fruity Grape
Methyl salicylate Minty, root beer Wintergreen
Hexyl acetate
Floral
, Fruity 		Apple, Plum

Linear terpenes

Compound name Fragrance Natural occurrence Chemical structure
Myrcene
 Woody, complex Verbena, Bay leaf
Geraniol Rose, flowery Geranium, Lemon
Nerol Sweet rose, flowery
Lemongrass
Citral, lemonal
Geranial, neral 		Lemon
Lemongrass
Citronellal Lemon
Lemongrass
Citronellol Lemon
Lemongrass, rose
Pelargonium
Linalool Floral, sweet
Woody
Lavender, Honeysuckle
Nerolidol Woody, fresh bark Neroli, ginger
Jasmine
Ocimene Fruity, Floral Mango, Curcuma amada

Cyclic terpenes

Compound name Fragrance Natural occurrence Chemical structure
Limonene Orange Orange, lemon
Camphor Camphor
Camphor laurel
Menthol Menthol Mentha
Carvone1 Caraway or Spearmint Caraway, dill,
spearmint
Terpineol
Lilac
cajuput
alpha-Ionone Violet, woody Violet
Thujone Minty
lilac,
juniper
Eucalyptol Eucalyptus Eucalyptus
Jasmone spicy, fruity, floral in dilution Jasmine, Honeysuckle

Note: Carvone, depending on its chirality, offers two different smells.

Aromatic

Compound name Fragrance Natural occurrence Chemical structure
Benzaldehyde Almond
Bitter almond
Eugenol Clove Clove
Cinnamaldehyde Cinnamon
Cassia
Cinnamon
Ethyl maltol Cooked fruit
Caramelized sugar
Vanillin Vanilla Vanilla
Anisole Anise Anise
Anethole Anise
Sweet basil
Estragole Tarragon Tarragon
Thymol Thyme Thyme

Amines

Compound name Fragrance Natural occurrence Chemical structure
Trimethylamine Fishy
Ammonia
Putrescine
Diaminobutane 		Rotting flesh Rotting flesh
Cadaverine Rotting flesh Rotting flesh
Pyridine Fishy Belladonna
Indole Fecal
Flowery 		Feces
Jasmine
Skatole Fecal
Flowery 		Feces
(diluted) Orange Blossoms

Other aroma compounds

Alcohols

Aldehydes

High concentrations of aldehydes tend to be very pungent and overwhelming, but low concentrations can evoke a wide range of aromas.

Esters

Ketones

Lactones

Thiols

Main article: Thiol

Miscellaneous compounds

Aroma-compound receptors

Animals that are capable of

sensory neurons in the olfactory system that detect airborne aroma compounds. Aroma compounds can then be identified by gas chromatography-olfactometry, which involves a human operator sniffing the GC effluent.[11]

In mammals, olfactory receptors are expressed on the surface of the olfactory epithelium in the nasal cavity.[5]

Safety and regulation

Patch test

In 2005–06, fragrance mix was the third-most-prevalent allergen in patch tests (11.5%).[12] 'Fragrance' was voted Allergen of the Year in 2007 by the American Contact Dermatitis Society. An academic study in the United States published in 2016 has shown that "34.7 % of the population reported health problems, such as migraine headaches and respiratory difficulties, when exposed to fragranced products".[13]

The composition of fragrances is usually not disclosed in the label of the products, hiding the actual chemicals of the formula, which raises concerns among some consumers.[14] In the United States, this is because the law regulating cosmetics protects trade secrets.[15]

In the United States, fragrances are regulated by the

EPA. The EPA, however, does not conduct independent safety testing but relies on data provided by the manufacturer.[16]

A 2019 study of the top-selling

skin moisturizers found 45% of those marketed as "fragrance-free" contained fragrance.[17]

List of chemicals used as fragrances

In 2010, the International Fragrance Association published a list of 3,059 chemicals used in 2011 based on a voluntary survey of its members, identifying about 90% of the world's production volume of fragrances.[18]

See also

References

  1. ^
    PMID 23852166
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  2. PMID 29533612
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  3. PMID 958345
    . Retrieved September 29, 2020.
  4. ISBN 978-3527306732
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  5. ^
    PMID 30830391
    .
  6. PMID 27746799
    .
  7. PMID 23372854
    .
  8. ^
    PMID 17009284
    .
  9. ISBN 978-0-85404-190-9
    .
  10. S2CID 162036
    .
  11. PMID 24316571
    .
  12. PMID 19470301
    .
  13. ^ Anne Steinemann, "Fragranced consumer products: exposures and effects from emissions", Air Quality, Atmosphere & Health, December 2016, Volume 9, Issue 8, pp 861–866.
  14. ^ Anne C. Steinemann et al., "Fragranced Consumer Products: Chemicals Emitted, Ingredients Unlisted", Environmental Impact Assessment Review, Vol. 31, Issue 3, April 2011, pp. 328-333.
  15. ^ a b Fragrances in Cosmetics
  16. ISBN 978-0-525-94951-0
    .
  17. ^ Patti Neighmond (October 2, 2017). "'Hypoallergenic' And 'Fragrance-Free' Moisturizer Claims Are Often False". NPR.
  18. ^ "IFRA Survey:Transparency List". IFRA. Retrieved December 3, 2014.
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