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.
An odorizer may add an odorant to a dangerous odorless substance, like propane, natural gas, or hydrogen, as a safety measure.
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Aroma compounds classified by structure
Esters
Linear terpenes
Cyclic terpenes
Note: Carvone, depending on its chirality, offers two different smells.
Aromatic
Amines
Pink Grapefruit Fragrance Oil Video
Other aroma compounds
Alcohols
- Furaneol (strawberry)
- 1-Hexanol (herbaceous, woody)
- cis-3-Hexen-1-ol (fresh cut grass)
- Menthol (peppermint)
Aldehydes
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
Esters
- Fructone (fruity, apple-like)
- Hexyl acetate (apple, floral, fruity)
- Ethyl methylphenylglycidate (strawberry)
Ketones
- 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)
Lactones
- 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)
Thiols
- Thioacetone (2-propanethione) A lightly studied organosulfur. Its 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 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)
Miscellaneous compounds
- Methylphosphine and dimethylphosphine (garlic-metallic, two of the most potent odorants known)
- Phosphine (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
Aroma-compound receptors
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.
In mammals, olfactory receptors are expressed on the surface of the olfactory epithelium in the nasal cavity.
Safety
In 2005-06, fragrance mix was the third-most-prevalent allergen in patch tests (11.5%).
'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.
Source of the article : Wikipedia
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