An aroma-compound, also known as an 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.
Aroma-compounds can be found in food, wine, spices, floral scent, perfumes, fragrance oils, and essential oils. For example, many form biochemically during the ripening of fruits and other crops. In wines, most form as byproducts of fermentation. 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
|Geranyl acetate||Fruity, Rose|| Rose,
|Methyl formate||Ethereal|| |
|Methyl acetate|| Sweet, nail-polish
| Methyl propionate
|Sweet, fruity, rum-like|| |
| Methyl butyrate
| Fruity, Apple
|Ethyl acetate||Sweet, solvent||Wine|| |
| Ethyl butyrate
| Fruity, Orange
|Isoamyl acetate|| Fruity, Banana
|Banana plant|| |
| Pentyl butyrate
| Fruity, Pear
|Pentyl pentanoate||Fruity, Apple|| |
|Octyl acetate||Fruity, Orange|| |
|Benzyl acetate||Fruity, Strawberry||Strawberries|| |
|Methyl anthranilate||Fruity, Grape|| |
|Myrcene||Woody, complex||Verbena, Bay leaf|| |
|Geraniol||Rose, flowery||Geranium, Lemon|| |
|Nerol||Sweet rose, flowery||Neroli, Lemongrass|| |
| Citral, lemonal
|Lemon||Lemon myrtle, Lemongrass|| |
|Citronellol||Lemon|| Lemongrass, rose
|Linalool|| Floral, sweet
| Coriander, Sweet basil
|Nerolidol||Woody, fresh bark|| Neroli, ginger
|Limonene||Orange||Orange, lemon|| |
|Camphor||Camphor||Camphor laurel|| |
|Carvone1||Caraway or Spearmint|| Caraway, dill,
|Terpineol||Lilac||Lilac, cajuput|| |
|alpha-Ionone||Violet, woody||Violet|| |
|Thujone||Minty|| Wormwood, lilac,
|Eucalyptol||Eucalyptus||Eucalyptus globulus|| |
Note: Carvone, depending on its chirality, offers two different smells.
|Benzaldehyde||Almond||Bitter almond|| |
|Ethyl maltol|| Cooked-fruit
(diluted) Orange Blossoms
- Furaneol (strawberry)
- 1-Hexanol (herbaceous, woody)
- cis-3-Hexen-1-ol (fresh cut grass)
- Menthol (peppermint)
High concentrations of aldehydes tend to be very pungent and overwhelming, but low concentrations can evoke a wide range of aromas.
- Acetaldehyde (ethereal)
- Hexanal (green, grassy)
- cis-3-Hexenal (green tomatoes)
- Furfural (burnt oats)
- Hexyl cinnamaldehyde
- Isovaleraldehyde – nutty, fruity, cocoa-like
- Anisic aldehyde – floral, sweet, hawthorn. It is a crucial component of chocolate, vanilla, strawberry, raspberry, apricot, and others.
- Cuminaldehyde (4-propan-2-ylbenzaldehyde) – Spicy, cumin-like, green
- Fructone (fruity, apple-like)
- Hexyl acetate (apple, floral, fruity)
- Ethyl methylphenylglycidate (strawberry)
- Cyclopentadecanone (musk-ketone)
- Dihydrojasmone (fruity woody floral)
- Oct-1-en-3-one (blood, metallic, mushroom-like)
- 2-Acetyl-1-pyrroline (fresh-bread, jasmine-rice)
- 6-Acetyl-2,3,4,5-tetrahydropyridine (fresh-bread, tortillas, popcorn)
- gamma-Decalactone intense-peach flavor
- gamma-Nonalactone coconut-odor, popular in suntan-lotions
- delta-Octalactone creamy-note
- Jasmine lactone powerful-fatty-fruity peach and apricot
- Massoia lactone powerful-creamy coconut
- Wine lactone sweet-coconut odor
- Sotolon (maple syrup, curry, fenugreek)
- Thioacetone (2-propanethione) A lightly studied organosulfur. It's smell is so potent it can be detected several hundred meters downwind mere seconds after a container is opened.
- Allyl thiol (2-propenethiol; allyl mercaptan; CH2=CHCH2SH) (garlic volatiles and garlic breath)
- (Methylthio)methanethiol (CH3SCH2SH), the "mouse thiol", found in mouse-urine and functions as a semiochemical for female-mice
- Ethanethiol, commonly called ethyl-mercaptan (added to propane or other liquefied-petroleum gases used as fuel-gases)
- 2-Methyl-2-propanethiol, commonly called tert-butyl mercaptan is added as a blend of other components to natural-gas used as fuel-gas.
- Butane-1-thiol, commonly called normal-butyl mercaptan is a chemical-intermediate.
- Grapefruit mercaptan (grapefruit)
- Methanethiol, commonly called methyl-mercaptan (after eating Asparagus)
- Furan-2-ylmethanethiol, also called furfuryl-mercaptan (roasted-coffee)
- Benzyl mercaptan (leek or garlic-like)
- Methylphosphine and dimethylphosphine (garlic-metallic, two of the most potent-odorants known)
- Phosphine (Green Apple, Zinc Phosphide poisoned bait)
- Diacetyl (Butter flavor)
- Acetoin (Butter flavor)
- Nerolin (orange flowers)
- Tetrahydrothiophene (added to natural gas)
- 2,4,6-Trichloroanisole (cork taint)
- Substituted pyrazines
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 air-borne, aroma-compounds.
'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.
Fragrances are regulated in the United States 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.
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. It was estimated to represent about 90% of the world's production-volume of fragrances.
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- Block, E. (2010). Garlic and Other Alliums: The Lore and the Science. Royal Society of Chemistry. ISBN 0-85404-190-7.
- Lin, D.Y.; Zhang, S.Z.; Block, E.; Katz, L.C. (2005). "Encoding social-signals in the mouse-main-olfactory bulb". Nature. 434: 470–477. doi:10.1038/nature03414.
- 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.
- Toxic-chemicals linked to birth-defects are being found at alarming-levels in women of childbearing-age
- Randall Fitzgerald. The Hundred Year Lie. Dutton, 2006. p. 23. ISBN 0-525-94951-8.
- "IFRA Survey:Transparency List". IFRA. Retrieved December 3, 2014.
- Flavour and Fragrance Journal
- Fragrances of the World
- Odor detection threshold
- Olfactory system
- Olfactory receptor
- Odorizer, a device for adding an odorant to gas flowing through a pipe
- Aroma of wine
- Eau de toilette