Aroma compound

An aroma compound, also known as odorant, aroma, fragrance, flavor, is a chemical compound that has a smell or odor. A chemical compound has a smell or odor when two conditions are met: the compound needs to be volatile, so it can be transported to the olfactory system in the upper part of the nose, and it needs to be in a sufficiently high concentration to be able to interact with one or more of the olfactory receptors.

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 natural gas, as a warning. As well many of the aroma compounds plays a significant role in the production of flavorants, which are used in the food service industry to flavor, improve and increase the appeal of their products.

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Aroma compounds classified by functional group

Alcohols

• Benzyl alcohol (oxidises to benzaldehyde, almond)
• Ethyl maltol (sugary, cooked fruit)
• Furaneol (strawberry)
• 1-Hexanol (herbaceous, woody)
• cis-3-Hexen-1-ol (fresh cut grass)
• Menthol (peppermint)

Aldehydes

• Acetaldehyde (pungent)
• Benzaldehyde (marzipan, almond)
• Hexanal (green, grassy)
• Cinnamaldehyde (cinnamon)
• Citral (lemongrass, lemon oil)
• cis-3-Hexenal (green tomatoes)
• Furfural (burnt oats)
• Neral (citrus, lemongrass)
• Vanillin (vanilla)

Amines

• Cadaverine (rotting flesh)
• Indole (jasmine flowery, feces)
• Putrescine (rotting flesh)
• Pyridine (very unpleasant)
• Skatole (bad breath, feces)
• Substituted pyrazines: 2-ethoxy-3-isopropylpyrazine, 2-methoxy-3-sec-butylpyrazine, 2-methoxy-3-methylpyrazine (toasted seeds of fenugreek, cumin, and coriander)
• Trimethylamine (fish)

Esters

• Ethyl acetate (fruity, solvent)
• Ethyl butanoate (fruity) - also known as ethyl butyrate
• Ethyl decanoate - also known as ethyl caprate
• Ethyl hexanoate - also known as ethyl caproate
• Ethyl octanoate - also known as ethyl caprylate
• Hexyl acetate (apple, floral, fruity)
• Isoamyl acetate (banana)
• Methyl butanoate (apple, fruity) - also known as methyl butyrate
• Methyl salicylate (oil of wintergreen)
• Pentyl butanoate (pear, apricot)
• Pentyl pentanoate (apple, pineapple)
• Sotolon (maple syrup, curry, fenugreek)
• Strawberry aldehyde (strawberry)

Ethers

• Anethole (liquorice, anise seed, ouzo, fennel)
• Anisole (anise seed)
• Eugenol (clove oil)
• 2,4,6-Trichloroanisole (cork taint)

Ketones

• Oct-1-en-3-one (blood, metallic, mushroom-like)^[1]
• 2-Acetyl-1-pyrroline (fresh bread, jasmine rice)
• 6-Acetyl-2,3,4,5-tetrahydropyridine (fresh bread, tortillas, pop corn)

Terpenes

• Camphor (Cinnamomum camphora)
• Citronellol (rose)
• Linalool (floral, citrus, coriander)
• Nerol (sweet rose)
• Nerolidol (wood, fresh bark)
• alpha-Terpineol (lilac)
• Thujone (juniper, common sage, Nootka cypress, and wormwood)
• Thymol (Thyme-like)

Thiols

• Ethanethiol, formerly called Ethyl mercaptan (Durian or leek, added to natural gas)
• Grapefruit mercaptan (grapefruit)
• Methanethiol, formerly called Methyl mercaptan (added to natural gas)

Miscellaneous compounds

• Methylphosphine and dimethylphosphine (garlic-metallic, two of the most potent odorants known)^[1]

• Nerolin (orange flowers)
• Tetrahydrothiophene (added to natural gas)

References

1. ^ ^{a b} D. Glindemann, A. Dietrich, H. Staerk, P. Kuschk, (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.

See also

• Odor
• Olfaction
• Olfactory system
• Olfactory receptor
• Pheromone
• Odor detection threshold