Aroma compound

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An aroma compound, also known as odorant, aroma, fragrance or flavor, is a chemical compound that has a smell or odor. A chemical compound has a smell or odor when it is sufficiently volatile to be transported to the olfactory system in the upper part of the nose.

Generally molecules meeting this specification have molecular weights of <300. Flavors affect both the sense of taste and smell whereas fragrances affect only smell. Flavors tend to be naturally occurring, and fragrances tend to be synthetic.[1]

Aroma compounds can be found in food, wine, spices, perfumes, fragrance oils, and essential oils. For example, many form biochemically during ripening of fruits and other crops. In wines, most form as byproducts of fermentation. Odorants can also be added to a dangerous odorless substance, like propane, natural gas, or hydrogen, as a warning. Also, many of the aroma compounds play a significant role in the production of flavorants, which are used in the food service industry to flavor, improve, and generally increase the appeal of their products.

Aroma compounds classified by structure[edit]

Esters[edit]

Compound name Fragrance Natural occurrence Chemical structure
Geranyl acetate Fruity, Rose Rose,
Floral
Geranyl acetate.svg
Methyl formate Ethereal
Methyl formate.svg
Methyl acetate Sweet, nail polish
Solvent
Methyl-acetate.svg
Methyl propionate
Methyl propanoate
Sweet, fruity, rum-like
Methyl propionate.svg
Methyl butyrate
Methyl butanoate
Fruity, Apple
Pineapple
Pineapple
Buttersauremethylester.svg
Ethyl acetate Sweet, solvent Wine
Ethyl acetate2.svg
Ethyl butyrate
Ethyl butanoate
Fruity, Orange
Pineapple
Ethyl butyrate2.svg
Isoamyl acetate Fruity, Banana
Pear
Banana plant
Isoamyl acetate.png
Pentyl butyrate
Pentyl butanoate
Fruity, Pear
Apricot
Pentyl butyrate.png
Pentyl pentanoate Fruity, Apple
Pentyl pentanoate.png
Octyl acetate Fruity, Orange
Octyl acetate.svg
Benzyl acetate Fruity, Strawberry Strawberries
Benzyl acetate.png
Methyl anthranilate Fruity, Grape
Methyl anthranilate.png

Linear terpenes[edit]

Compound name Fragrance Natural occurrence Chemical structure
Myrcene Woody, complex Verbena, Bay leaf
Myrcene beta straight acsv.svg
Geraniol Rose, flowery Geranium, Lemon
Geraniol structure.png
Nerol Sweet rose, flowery Neroli, Lemongrass
Nerol2.png
Citral, lemonal
Geranial, neral
Lemon Lemon myrtle, Lemongrass
Geranial structure.png
Citronellal Lemon Lemongrass
Citronellal-2D-skeletal.png
Citronellol Lemon Lemongrass, rose
Pelargonium
Citronellol-2D-skeletal.png
Linalool Floral, sweet
Woody, Lavender
Coriander, Sweet basil
Lavender
Linalool-skeletal.png
Nerolidol Woody, fresh bark Neroli, ginger
Jasmine
Nerolidol.png

Cyclic terpenes[edit]

Compound name Fragrance Natural occurrence Chemical structure
Limonene Orange Orange, lemon
Limonene-2D-skeletal.svg
Camphor Camphor Camphor laurel
Camphor structure.png
Menthol Menthol Mentha
Menthol skeletal.svg
Carvone1 Caraway or Spearmint Caraway, dill,
spearmint
Carvone.svg
Terpineol Lilac Lilac, cajuput
Terpineol alpha.svg
alpha-Ionone Violet, woody Violet
Alpha-ionone-label.png
Thujone Minty Wormwood, lilac,
juniper
Beta-Thujone.svg

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

Aromatic[edit]

Compound name Fragrance Natural occurrence Chemical structure
Benzaldehyde Almond Bitter almond
Benzaldehyde.png
Eugenol Clove Clove
Eugenol acsv.svg
Cinnamaldehyde Cinnamon Cassia
Cinnamon
Zimtaldehyd - cinnamaldehyde.svg
Ethyl maltol Cooked fruit
Caramelized sugar
Ethyl maltol.png
Vanillin Vanilla Vanilla
Vanillin.svg
Anisole Anise Anise
Anisol.svg
Anethole Anise Anise
Sweet basil
Anethole-structure-skeletal.png
Estragole Tarragon Tarragon
Estragole acsv.svg
Thymol Thyme Thyme
Thymol2.svg

Amines[edit]

Compound name Fragrance Natural occurrence Chemical structure
Trimethylamine Fishy
Ammonia
Trimethylamine chemical structure.png
Putrescine
Diaminobutane
Rotting flesh Rotting flesh
Diaminobutane.png
Cadaverine Rotting flesh Rotting flesh
Cadaverine-2D-skeletal.png
Pyridine Fishy Belladonna
Pyridin.svg
Indole Fecal
Flowery
Feces
Jasmine
Indol2.svg
Skatole Fecal Feces
(diluted) Orange Blossoms
Skatole structure.svg

Other aroma compounds[edit]

Alcohols[edit]

Aldehydes[edit]

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

Esters[edit]

Ketones[edit]

Lactones[edit]

Thiols[edit]

Miscellaneous compounds[edit]

Aroma compound receptors[edit]

Animals that are capable of smell detect aroma compounds with olfactory receptors. Olfactory receptors are cell membrane receptors on the surface of sensory neurons in the olfactory system that detect air-borne aroma compounds.

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

Safety[edit]

In 2005–06, fragrance mix was the third-most-prevalent allergen in patch tests (11.5%).[6]

'Fragrance' was voted Allergen of the Year in 2007 by the American Contact Dermatitis Society. The composition of fragrances is usually not disclosed in the label of products, hiding the actual chemicals of the formula, which raises concerns among some consumers.[7]

References[edit]

  1. ^ Karl-Georg Fahlbusch, Franz-Josef Hammerschmidt, Johannes Panten, Wilhelm Pickenhagen, Dietmar Schatkowski, , Kurt Bauer, Dorothea Garbe and Horst Surburg "Flavors and Fragrances" Ullmann's Encyclopedia of Industrial Chemistry, 2003, Wiley-VCH. doi:10.1002/14356007.a11_141
  2. ^ 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, e55780. doi: 10.1371/journal.pone.0055780
  3. ^ 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. 
  4. ^ Block, E. (2010). Garlic and Other Alliums: The Lore and the Science. Royal Society of Chemistry. ISBN 0-85404-190-7. 
  5. ^ Lin, D.Y., Zhang, S.Z., Block, E., and Katz, L.C. (2005). "Encoding social signals in the mouse main olfactory bulb." Nature 434, 470–477.
  6. ^ Zug KA, Warshaw EM, Fowler JF Jr, Maibach HI, Belsito DL, Pratt MD, Sasseville D, Storrs FJ, Taylor JS, Mathias CG, Deleo VA, Rietschel RL, Marks J. Patch-test results of the North American Contact Dermatitis Group 2005–2006. Dermatitis. 2009 May–Jun;20(3):149-60.
  7. ^ Toxic chemicals linked to birth defects are being found at alarming levels in women of childbearing age

See also[edit]