Unlocking The Science Of Aroma: Counting Compounds

Aroma compounds, also known as odorants, fragrances, or flavourings, are chemical compounds that have a smell or odour. They are volatile compounds that are small enough to be transmitted via the air to the olfactory system in the upper part of the nose. Aroma compounds can be found in various foods, such as fruits, wine, spices, perfumes, and essential oils. They are also added to dangerous, odourless substances as a safety measure.

There are over 7000 volatile organic compounds (VOCs) isolated from foods, but only about 5% of them contribute to food aroma. The aroma compounds that do contribute to food aroma are present in a wide concentration range and have low molecular weights of less than 400 Da.

The number of aroma compounds can vary depending on the food product. For example, wines have more than 100 aroma compounds, while strawberries contain several hundred.

Aroma compounds are volatile chemical compounds with a smell or odour

Aroma compounds, also known as odorants, aromas, fragrances, or flavorings, are volatile chemical compounds with a smell or odour. These compounds are small, with molecular weights of less than 310 Daltons, and can easily evaporate at room temperature and pressure. This volatility allows them to be transmitted via the air to the olfactory system in the upper part of the nose, where they can be detected by humans and other animals through the sense of smell or olfaction.

Odors can be naturally occurring or synthetically produced and are used in various products such as perfumes, cosmetics, and food flavourings. For example, wines have more than 100 aromas that form as byproducts of fermentation. Aroma compounds are also added to odorless substances like natural gas as a safety measure.

The sense of smell can detect odors at extremely low concentrations, and researchers estimate that humans can distinguish between 10,000 and one trillion different odors. The brain interprets the mix of compounds as a whole rather than individual compounds or their relative concentrations.

Organic odorants fall into several categories, including esters, terpenes, amines, aromatics, aldehydes, alcohols, thiols, ketones, and lactones. Some common examples of aroma compounds include:

• Furaneol (strawberry)
• 1-Hexanol (herbaceous, woody)
• Cis-3-Hexen-1-ol (fresh cut grass)
• Menthol (peppermint)
• Anisic aldehyde (floral, sweet, hawthorn)
• Thioacetone (organosulfur)

They are naturally present in foods, or generated by chemical, biochemical, or microbial changes during their extraction, processing, and storage

Aroma compounds are chemical compounds that have a smell or odour. They are an important factor in food quality and safety, impacting consumer preference and acceptance. These compounds can be naturally present in foods as a result of physiological and/or enzymatic processes, or they can be generated by microorganisms during fermentation processes.

In addition, aroma compounds can also be produced or modified due to chemical, biochemical, or microbial changes during the extraction, processing, and storage of foods. This can affect the overall food quality, sensory profile, and shelf life. During processing, aroma compounds are generated by enzymatic activity, fermentation, lipid oxidation, and thermal reactions such as the Maillard reaction and caramelization.

Thermal technologies, for example, increase food safety but also accelerate chemical reactions, inducing modifications in the food components. Heat-generated flavours, in fact, constitute the most abundant group of volatile organic compounds (VOCs) in food.

The complex mixture of organic chemical compounds that make up food aroma can exist in a gaseous state at room temperature, allowing them to be detected by our sense of smell. These compounds are typically small, with molecular weights of less than 300 Daltons, and are readily dispersed in the air due to their high vapour pressure.

The presence of aroma compounds in food can be analysed using various techniques such as headspace solid-phase microextraction, solvent-assisted flavour evaporation, and solid-phase extraction.

They are classified as organic acids, primary and secondary alcohols, amines, carbonyl compounds, esters, lactones, and more

Aroma compounds, also known as odorants, aromas, fragrances or flavourings, are chemical compounds that have a smell or odour. They are volatile compounds that can be transmitted via the air to the olfactory system in the upper part of the nose.

Aroma compounds are classified based on their chemical structures. They can be grouped into acids, hydrocarbons, aldehydes, alcohols, ketones, esters, or lactones.

Organic Acids

Organic acids are not typically considered or regulated as flavourants by law. However, they can impart a sour taste that alters the flavour of food. Examples include acetic acid, which gives vinegar its sour taste and distinctive smell, and citric acid, which gives citrus fruits their sour taste.

Alcohols

Alcohols are a significant group of aroma compounds. Examples include benzyl alcohol, which oxidises to benzaldehyde and has an almond scent, and menthol, which has a peppermint scent.

Amines

Amines are another important class of aroma compounds. Examples include cadaverine, which has a rotting flesh scent, and putrescine, which has a similar rotting flesh scent.

Carbonyl Compounds

Carbonyl compounds, such as aldehydes and ketones, are also important aroma compounds. Acetaldehyde, for instance, has a pungent odour, while benzaldehyde has notes of marzipan and almond. Ketones, such as octenone, can give a blood, metallic, or mushroom-like aroma effect.

Esters

Esters are aroma compounds that often have fruity scents. Examples include ethyl acetate, which has a fruity aroma, and ethyl butanoate, which has a banana scent.

Lactones

Lactones are cyclic compounds with ester functional groups. They enhance fruity, oily, and sweet notes. Lactones are known for producing a sweet coconut odour.

These classifications only scratch the surface of the complex world of aroma compounds. The sense of smell can detect a vast array of odours, and aroma compounds can be found in many natural sources, such as fruits, spices, and essential oils.

They are detected by the olfactory receptors in the upper part of the nose

Aroma compounds, also known as odorants, aromas, fragrances, or flavorings, are chemical compounds that have a smell or odour. These compounds are small, with molecular weights of less than 310, and are easily dispersed in the air.

Organisms that have a sense of smell detect aroma compounds through special sensory neurons called olfactory receptor (OR) cells. In humans, these cells are clustered at the back of the nasal cavity. Each sensory neuron has cilia that extend into the air, and on these cilia are receptor proteins that bind to aroma compounds. When this binding occurs, a chemical stimulus is initiated, creating an electric signal in the neuron. This signal is then transmitted to the olfactory nerve, which carries the signal to the olfactory bulb in the brain.

The olfactory bulb is part of the limbic system, which is associated with emotions. This is why a person may recognise an odour and relate it to an emotional experience, even if they are unable to identify the specific components of the scent. This is because the brain interprets the mix of compounds as a whole, rather than individual compounds or their relative concentrations.

In mammals, olfactory receptors are expressed on the surface of the olfactory epithelium in the nasal cavity. These receptors constitute one of the largest families of G-protein-coupled receptors and are distributed throughout the genome. Olfactory receptors are highly specific, with monogenic expression being the general rule, meaning that one neuron expresses one receptor.

The human nose is incredibly sensitive to certain aroma compounds, such as thioacetone, which can be detected within seconds if a container is opened hundreds of meters away.

Aroma compounds are added to dangerous, odourless substances as a safety measure

Aroma compounds, also known as odorants, aromas, fragrances, or flavorings, are chemical compounds that have a smell or odour. They are small, volatile molecules with molecular weights of less than 310 Daltons. These compounds are readily dispersed in the air and can be detected by the human olfactory system, which is located in the upper part of the nose.

Aroma compounds can be found naturally in various foods, such as fruits, wines, spices, and floral scents. They are also used in perfumes, cosmetics, and essential oils. Additionally, they play a significant role in the food industry, where they are used to enhance the flavour and improve the appeal of products.

One important application of aroma compounds is in adding a detectable odour to dangerous, odourless substances. This practice is known as "odorizing" and is done as a safety measure. For example, an odour may be added to odourless gases like propane, natural gas, or hydrogen to make them easier to detect in the event of a leak. This simple precaution can help prevent accidents and keep people safe.

The addition of an aroma compound to an odourless substance can be a literal lifesaver. Without our sense of smell, we would be unable to detect dangerous substances in the air, such as gas leaks. By adding a distinct odour to these otherwise undetectable gases, we gain the ability to identify and avoid potential hazards. This is a classic example of safety through scent.

Furthermore, the sense of smell is deeply connected to memory and emotion. The olfactory bulb, which processes odours, is part of the limbic system, which is associated with emotions and memory formation. This means that the addition of an aroma compound to an odourless substance can not only make it detectable but also help people form strong memories associated with that scent. This could further enhance safety by creating a lasting impression of the dangers associated with the substance.

In conclusion, the addition of aroma compounds to dangerous, odourless substances is a crucial safety measure. By making these substances detectable through scent, we gain the ability to identify and avoid potential hazards. Furthermore, the connection between smell and memory can lead to the formation of lasting impressions, ensuring that people remain vigilant and aware of the dangers posed by these substances.

Frequently asked questions