Perfume is a mixture of fragrance compounds, fixatives and solvents used to give the human body, animals, food and objects an agreeable scent. It is a major industry and an essential part of life for millions of people around the world.
The history of perfume is a fascinating one that stretches back to the ancient world. During the first millennium, perfumes were only reserved for religious ceremonies. Then, in the 1190s, perfume began to be produced commercially in Paris.
Early perfumes were mostly made from natural ingredients that were pressed, extracted and distilled by hand. But as organic chemists developed methods to synthesise molecules, new scents were possible.
In the 19th century, synthetic aromatics became widely available. These gave perfumers the ability to create a wide range of new odours that had never before been created. These included a range of molecules from the most exotic plants and herbs, to common, familiar ingredients like vanilla.
Despite this new availability of synthetics, perfumers still rely on nature-sourced components, such as essential oils, for the majority of their scents. These are usually extracted from fruit peels, such as limes, lemons and oranges, using a variety of methods, including extraction and distillation.
The aroma compounds in these essential oils are a vital part of the perfume making process, as they act to combine with other perfume ingredients and create the finished fragrance. These aroma compounds are divided into three classes: top notes, middle notes and base notes (also known as heart notes).
Top notes consist of odoriferous molecules that evaporate quickly and form the initial impression of a fragrance. These are often the strongest and most noticeable of the perfume’s compounds, so it is important that they be well-developed and balanced in a perfume.
Middle notes are the next layer of scent to emerge from a fragrance, and are less intense than top or base notes. These compounds act to smooth out the rough edges of the fragrance and provide a more harmonious scent accord. Examples of middle notes include sandalwood, nutmeg and jasmine.
Bottom notes are the final layer of the perfume, and are characterized by odoriferous molecules that evaporate slowly. These are generally less concentrated than the other types of fragrances, and may also contain more fatty substances.
These odours are often associated with feelings of pleasure and euphoria, but they can also be related to mood or mental health issues. They can also affect the chemistry of the brain and produce physiological effects, such as a reduction in stress levels.
As a result of this link between emotions and smells, there is a wide range of olfactory research being undertaken. For example, a recent study found that vanilla scent induced a 63% decrease in stress in patients under MRI scans.
In addition to studying how olfactory perception and emotions are linked, there is also an active interest in how perfume can contribute to our biological and psychological wellbeing. This includes studies of the neurobiological effects of fragrances, as well as the ways in which they can be used to improve reproductive success and enhance our relationships.