Smells, Aromas, Bouquets, Flavors and other Olfactory Stuff

First published on Distillique's website 2015 GM Bosman

Most of us have not been taught aroma descriptors, or aroma names, while we were kids, but all of us have been taught colors, and we easily agree on what is green, red or blue. The same is not (yet) true for aromas.

A heavy argument may arise with one person calling a specific aroma "leafy", while another may call the same aroma "grassy", and still another may call it "cut grass".

On the other hand, a single person may describe three totally different aromas as "leafy" (containing hexanol) , another aromas as grassy (like in dried grass, somewhat reminiscent of hay and dust) and another aroma as "cut grass" (smelling like freshly mown kikuyu (Pennisetum clandestinum) grass).

In the above example it is not a matter of who is right and who is wrong. It is a matter of agreement and standardization.

The color blue can defined as the color of light with a wavelength between 450 and 495 nano-meters. Simple. However with aromas it is not so easy to define or describe any particular aroma unless we have a sample of that specific aroma.

A lot of  work is being performed internationally to artificially/repeatedly manufacture molecules with specific aromatic characters.

Once it is known how to manufacture a specific molecule, it can be used as a standard. Natural aromas tend to change over time and they are unsuitable to train our noses. Think how the aroma of natural butter changes over time (from fresh butter to rancid butter to eventually a very stale aroma). However, diacetyl (a chemical than can be repeatedly isolated and be manufactured) is now used as the standard "molecule" for the standardized "buttery" aroma. If you smell diacetal, we will call it buttery and likewise, if someone describes "a buttery aroma", we can assume the person is referring to diacetyl.

A few definitions to “standardize” our language when talking about all things “smelling”

• Smell: The quality of things that we sense with our noses (or more correctly: a characteristic of gaseous/volatile molecules that we perceive and identify with our olfactory sense).

• Aroma: a distinctive pervasive and usually pleasant smell

• Aromatic: In general talk, we say that something is aromatic when it contains strong aromas. However, Aromatic can also be used to describe a specific group of smells based on its chemical structure. Many spices can rightly be called aromatic because they contain strong aromas as well as sharing structural similarities of their chemicals.

• Odor: A distinctive pervasive and usually unpleasant smell

• Bouquet: A combination of a few aromas – usually associated with wine but used more and more for all spirits and beer as well

• Stink: A combination of a few odors – always smelling bad/unattractive.

• Fragrance: A sweet or delicate smell – normally associated with perfume or flowers

• Taste: The quality of things that we sense with our tongue (or more correctly: a characteristic of gaseous and or dissolved molecules that we perceive and/or identify with taste-buds on our tongue)

• Flavor: a combination of taste and smell.

• Flavorant: a combination of chemical substances (100% natural or not) to provide flavor to food or drinks.
   
• Alcohol extract: Botanical materials (herbs, spices, plants, fruits etc) which have been infused in alcohol (ethanol) in order for the alcohol to dissolve and extract the flavorants and other components (i.e. color) from the material.

• Tincture: If the alcohol extract is used for medicinal purposes, it is called a tincture.

• Absolute: An alcohol extract, from which the alcohol has been extracted from, leaves the absolute behind. (i.e. only the flavorants and other solubles are left behind)

• Concrete: A concentrate, waxy, semi-solid or solid perfume material extract made from an alcohol extract from which the alcohol has been completely removed

• Enfleurage: The process for making perfumes in which odorless fats or oils absorb the fragrance of fresh flowers.

• Expression: The extraction of essential oils and non-volatile materials by pressing the natural material.

• Extraction: The process of removing botanical components from a raw material by using distillation, solvents, heat or pressure.

• Infusion:  Extraction of materials from plant matter by soaking in cold or warm liquid solvents such as ethanol.

• Maceration: Soaking until soft

• Fixative: A material that slows down the rate of evaporation of more volatile components.

• Hydrosol: Water containing dissolved volatile substances from plant material.