The Aromatic World: Understanding Scents And Their Meanings

Aromatic refers to something that has a pleasant smell, such as a plant, spice, or medicine. The word is derived from the Greek arōmatikós, meaning sweet spice. Aromatic compounds in chemistry refer to organic compounds with a benzene ring or similar structure, which often have a distinctive fragrance. Aromatic plants and spices are commonly used in cooking to add flavour and aroma to dishes.

Aromatic plants, drugs, and medicines

Other popular aromatic plants include rose, jasmine, lilac, lemongrass, mint, and cedarwood. These plants are frequently used in perfumery and to create fragrances for homes and businesses. The rose, in particular, is a staple of love and romance and is used in everything from cosmetics and perfumes to culinary favourites. The jasmine flower, on the other hand, has a long history of use in perfumes and incense, especially in Middle Eastern art and culture.

Aromatic compounds also play a significant role in the pharmaceutical industry, with many drugs and medicines containing aromatic rings. For instance, common analgesics and anti-inflammatory drugs like Aspirin (acetylsalicylic acid), Paracetamol (N-(4-hydroxyphenyl)ethanamide), and Ibuprofen (2-(4-(2-methylpropyl)phenyl)propanoic acid) are all synthetic aromatic compounds. Furthermore, aromatic compounds are often used as a starting point for drug design and discovery, with molecular dynamics simulations providing valuable insights into the behaviour of these compounds in biological systems.

Aromatic organic compounds

Aromatic compounds are typically unreactive, non-polar, hydrophobic, and have a high carbon-hydrogen ratio. They are commonly used as solvents for various nonpolar compounds.

Aromatic compounds are broadly classified into two categories: benzenoids, which contain a benzene ring, and non-benzenoids, which do not contain a benzene ring. Examples of benzenoid compounds include benzene, toluene, and phenol, while furan is an example of a non-benzenoid compound.

The unique stability of aromatic compounds, known as aromaticity, is due to particular bonding arrangements that strongly hold certain pi (π) electrons within a molecule. Aromaticity is often reflected in smaller-than-expected heats of combustion and hydrogenation and is associated with low reactivity.

Aromatic compounds play a crucial role in the biochemistry of all living things, including amino acids and nucleotides that make up the sequence of the genetic code in DNA and RNA. They are also important in industry, with key aromatic hydrocarbons such as benzene, toluene, and xylene having commercial interest.

To be classified as an aromatic compound, a molecule must meet four key conditions:

• The molecule must be cyclic.
• Every atom in the ring must be conjugated.
• The molecule must have [4n+2] pi electrons, where n is an integer (n = 0, 1, 2, 3, etc.). This is known as Hückel's Rule.
• The molecule must be flat or planar.

These conditions are essential for a molecule to exhibit aromaticity, a property of unusually stable organic molecules. While some aromatic molecules have a pleasant smell, the term "aromaticity" is unrelated to olfactory properties.

Aromatic in food

Aromatics are vegetables, herbs, and spices that add aroma and flavour to dishes. They are typically cooked in oil or fat at the beginning of the cooking process, which releases an addictive aroma and infuses a rich flavour into the dish. Aromatics are used in a wide variety of cuisines and can be combined in various ways to create different flavour profiles.

Aromatics in Different Cuisines

Aromatics are used in many different cuisines to create unique flavour profiles. Here are some examples:

• Thai cuisine emphasises lightly prepared dishes with a strong aromatic component and a spicy edge. A combination of roasted shallots, garlic, and chillies in cooking oil or coconut milk is commonly used. Other ingredients such as lemongrass, kaffir lime, and galangal (a plant in the ginger family with anti-inflammatory and antioxidant properties) are also used to enhance the aromatic profile.
• Middle Eastern cuisine is influenced by the Mediterranean climate, ancient religions, and cultures from Europe, Asia, and Africa. Local herbs and spices such as nutmeg, caraway, cumin, turmeric, parsley, and mint are added to dishes to create a deep aromatic smell and flavour. Saffron, one of the most expensive ingredients in the world, is also used for its flavour, colour, and aroma.
• Indian cuisine commonly uses a combination of roasted onions, garlic, chillies, and ginger in ghee (clarified butter) as a base for their aromatic profile. This flavour profile is then enhanced with various spices, including cumin, curry powder, cloves, garam masala, and turmeric.
• Latin cuisine is known for its sofrito, a blend of onions, peppers, garlic, and tomato that forms the basis of many dishes such as beans and stews. This savoury mixture is sautéed over medium heat in cooking oil to infuse a deeper flavour into the dish.
• Italian cuisine uses a combination of onions, celery, and carrots, known as soffritto, as the base for many dishes such as soups, stews, pasta sauces, and braises. This mixture is typically cooked slowly in olive oil or butter to develop a versatile and umami-packed flavour.
• French cuisine uses a similar combination of onions, carrots, and celery, called mirepoix, as its aromatic base. This mixture is cooked in butter to develop a sweet and aromatic flavour, often with the addition of Herbes de Provence, a spice blend commonly used in the Provence region of France.
• Chinese cuisine varies across different regions, but a common aromatic base is a combination of garlic, scallions, and ginger heated in cooking oil. To boost the flavour profile, additional ingredients such as Chinese five-spice, cilantro, chillies, shallots, chives, and star anise can be added.
• Cajun cuisine often uses a combination of onions, celery, and bell peppers, known as the "Holy Trinity," as the base for many classic dishes such as Gumbo and Jambalaya. Garlic is often added to this combination, and other ingredients such as parsley, shallots, and paprika are used for additional depth of flavour.

Using Aromatics in Cooking

Aromatics are typically used at the beginning of a dish, heated in fat to release their flavours and aromas. They can be chopped into uniform sizes, with the size depending on whether they will be left in the final dish or removed. If the aromatics will be removed, such as in stocks or sauces, larger pieces are fine. If they will be left in the dish, they should be finely diced or chopped to blend with the texture of the final dish.

Aromatics can be gently heated or "sweated" in fat, such as oil or butter, to soften them without browning. This technique is common in soups, where the aromatics are cooked in a small amount of oil or butter before adding other ingredients.

Aromatics are essential in creating flavourful dishes and can be used in a wide variety of combinations to create unique flavour profiles for different cuisines. Experimenting with different aromatics and combinations can enhance your cooking and create delicious and aromatic meals.

Aromatic in chemistry

Aromaticity is a chemical property used in organic chemistry to describe a conjugated ring of unsaturated bonds, lone pairs, or empty orbitals that exhibits stronger stabilization than expected by the stabilization of conjugation alone. Aromatic compounds are chemical compounds that consist of conjugated planar ring systems accompanied by delocalized pi-electron clouds in place of individual alternating double and single bonds.

The term "aromatic" was first used in 1855 by August Wilhelm Hofmann to refer to compounds that contain the phenyl radical. However, the current use of the term in chemistry is restricted to compounds that have particular electronic, structural, or chemical properties, and has nothing to do with smell. Aromatic compounds are typically unreactive, non-polar, hydrophobic, and have a high carbon-to-hydrogen ratio.

The unique stability of these compounds is referred to as aromaticity, which results from particular bonding arrangements that cause certain pi (π) electrons within a molecule to be strongly held. Aromaticity is often reflected in smaller-than-expected heats of combustion and hydrogenation and is associated with low reactivity. Benzene is the best-known aromatic compound and is the parent compound to which numerous other aromatic compounds are related.

There are four key rules for aromaticity:

• The molecule must be cyclic.
• Every atom in the ring must be conjugated.
• The molecule must have 4n+2 pi electrons, where n is an integer (n=0, 1, 2, etc.).
• The molecule must be flat.

Aromatic compounds play key roles in the biochemistry of all living things. For example, the four aromatic amino acids histidine, phenylalanine, tryptophan, and tyrosine are basic building blocks of proteins. Additionally, all five nucleotides that make up the sequence of the genetic code in DNA and RNA are aromatic purines or pyrimidines. Aromatic compounds are also important in industry, with key aromatic hydrocarbons including benzene, toluene, ortho-xylene, and para-xylene.

Aromatic vs. aroma

The word "aromatic" is derived from the Greek "aromatikos", meaning "sweet spice". Aromatic is an adjective used to describe something with a pleasant smell, such as fragrant roses, spices, or freshly cut grass. In chemistry, it is also used to describe organic compounds with benzene rings, such as naphthalene and TNT. Aromatic can also be used as a noun to refer to fragrant plants, herbs, or spices.

On the other hand, "aroma" is a noun that simply refers to a smell, which could be pleasant or unpleasant. For example, one might say, "I love the aroma of cinnamon", or "the toilet was emitting a pungent aroma".

While related, the key difference between the two words is that "aromatic" describes something with a pleasant smell, whereas "aroma" simply refers to a smell, regardless of whether it is pleasant or not.

In organic chemistry, the term "aromatic" is used to describe a specific type of compound with a closed ring of alternate single and double bonds with delocalized electrons, often derived from benzene. These compounds are characterised by increased chemical stability due to their structure.

Frequently asked questions