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Aroma compound

(Redirected from Odorants)
Several terms redirect here. For other uses, see Fragrance (disambiguation), Fragrant, Kentucky, and The Odorants.
Not to be confused with Aromatic compound.

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]

Fragrance bottles

Generally, molecules meeting this specification have molecular weights of less than 310.[3] Flavors affect both the sense of taste and 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 foods, such as fruits and their peels, wine, spices, floral scent, perfumes, fragrance oils, and essential oils. For example, many form biochemically during the ripening of fruits and other crops.[1][5] Wines have more than 100 aromas that form as byproducts of 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

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Esters

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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

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

Cyclic terpenes

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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 Lilac, cajuput
 
alpha-Ionone Violet, woody Violet
 
Thujone Minty Wormwood, lilac,
juniper
 
Eucalyptol Eucalyptus Eucalyptus
 
Jasmone spicy, fruity, floral in dilution Jasmine, Honeysuckle
 

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

Aromatic

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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 Anise
Sweet basil
 
Estragole Tarragon Tarragon
 
Thymol Thyme Thyme
 

Amines

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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

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Alcohols

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Aldehydes

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

Esters

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Ketones

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Lactones

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Thiols

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Main article: Thiol

Miscellaneous compounds

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Aroma-compound receptors

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Animals that are capable of smell detect aroma compounds with their olfactory receptors. Olfactory receptors are cell-membrane receptors on the surface 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

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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 Food and Drug Administration if present in cosmetics or drugs, by the Consumer Products Safety Commission if present in consumer products.[15] No pre-market approval is required, except for drugs. Fragrances are also generally regulated by the Toxic Substances Control Act of 1976 that "grandfathered" existing chemicals without further review or testing and put the burden of proof that a new substance is not safe on 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

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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

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References

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  1. ^ a b c d El Hadi, Muna; Zhang, Feng-Jie; Wu, Fei-Fei; Zhou, Chun-Hua; Tao, Jun (July 11, 2013). "Advances in fruit aroma volatile research". Molecules. 18 (7): 8200–8229. doi:10.3390/molecules18078200. ISSN 1420-3049. PMC 6270112. PMID 23852166.
  2. ^ Ulrich, Detlef; Kecke, Steffen; Olbricht, Klaus (March 13, 2018). "What do we know about the chemistry of strawberry aroma?". Journal of Agricultural and Food Chemistry. 66 (13): 3291–3301. doi:10.1021/acs.jafc.8b01115. ISSN 0021-8561. PMID 29533612.
  3. ^ Rothe, M; Specht, M (1976). "[Notes about molecular weights of aroma compounds]". Nahrung. 20 (3): 281–6. doi:10.1002/food.19760200308. PMID 958345. Retrieved September 29, 2020.
  4. ^ Fahlbusch, Karl-Georg; Hammerschmidt, Franz-Josef; Panten, Johannes; Pickenhagen, Wilhelm; Schatkowski, Dietmar; Bauer, Kurt; Garbe, Dorothea; Surburg, Horst. "Flavors and fragrances". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a11_141. ISBN 978-3527306732.
  5. ^ a b Haugeneder, Annika; Trinkl, Johanna; Härtl, Katja; Hoffmann, Thomas; Allwood, James William; Schwab, Wilfried (October 26, 2018). "Answering biological questions by analysis of the strawberry metabolome". Metabolomics. 14 (11): 145. doi:10.1007/s11306-018-1441-x. ISSN 1573-3882. PMC 6394451. PMID 30830391.
  6. ^ Ilc, Tina; Werck-Reichhart, Danièle; Navrot, Nicolas (September 30, 2016). "Meta-analysis of the core aroma components of grape and wine aroma". Frontiers in Plant Science. 7: 1472. doi:10.3389/fpls.2016.01472. ISSN 1664-462X. PMC 5042961. PMID 27746799.
  7. ^ Gane, S; Georganakis, D; Maniati, K; Vamvakias, M; Ragoussis, N; Skoulakis, EMC; Turin, L (2013). "Molecular-vibration-sensing component in human olfaction". PLOS ONE. 8 (1): e55780. Bibcode:2013PLoSO...855780G. doi:10.1371/journal.pone.0055780. PMC 3555824. PMID 23372854.
  8. ^ a b Glindemann, D.; Dietrich, A.; Staerk, H.; Kuschk, P. (2005). "The Two Odors of Iron when Touched or Pickled: (Skin) Carbonyl Compounds and Organophosphines". Angewandte Chemie International Edition. 45 (42): 7006–7009. doi:10.1002/anie.200602100. PMID 17009284.
  9. ^ Block, E. (2010). Garlic and Other Alliums: The Lore and the Science. Royal Society of Chemistry. ISBN 978-0-85404-190-9.
  10. ^ Lin, D.Y.; Zhang, S.Z.; Block, E.; Katz, L.C. (2005). "Encoding social signals in the mouse main olfactory bulb". Nature. 434 (7032): 470–477. Bibcode:2005Natur.434..470L. doi:10.1038/nature03414. PMID 15724148. S2CID 162036.
  11. ^ Brattoli, M; Cisternino, E; Dambruoso, PR; de Gennaro, G; Giungato, P; Mazzone, A; Palmisani, J; Tutino, M (December 5, 2013). "Gas chromatography analysis with olfactometric detection (GC-O) as a useful methodology for chemical characterization of odorous compounds". Sensors (Basel, Switzerland). 13 (12): 16759–800. Bibcode:2013Senso..1316759B. doi:10.3390/s131216759. PMC 3892869. PMID 24316571.
  12. ^ Zug, Kathryn A.; Warshaw, Erin M.; Fowler, Joseph F.; Maibach, Howard I.; Belsito, Donald L.; Pratt, Melanie D.; Sasseville, Denis; Storrs, Frances J.; Taylor, James S.; Mathias, C. G. Toby; Deleo, Vincent A.; Rietschel, Robert L.; Marks, James (2009). "Patch-test results of the North American Contact Dermatitis Group 2005-2006". Dermatitis: Contact, Atopic, Occupational, Drug. 20 (3): 149–160. ISSN 2162-5220. 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. ^ Randall Fitzgerald (2006). The Hundred Year Lie. Dutton, 2006. p. 23. 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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