In ancient civilizations perfume was used to anoint the body and to scent clothes, food, living-spaces and animals. In modern times, perfumes are made from a combination of fragrant oils and aroma compounds in liquid form that are used to scent the skin or clothing. Perfumes may be made from natural or synthetic sources. The odorants in perfumes are thought to have a number of psychotherapeutic and pharmacological effects including mood enhancement, anxiety reduction, memory recall and positive psychological and physiological consequences such as heart rate and blood pressure decreases. The precise mechanisms of these olfactory effects are not fully understood but are believed to involve associative learning, immediate neural and emotional responses and a pharmacological interaction with the brain’s endocrine system.
The raw materials that are used to make perfumes range from animal secretions and plant oils to musk, ambergris, and other synthetic chemicals. Most perfumes contain a mixture of these ingredients, with the concentration of oil-based products (eau de parfum, eau de toilette) being higher than those containing alcohol (eau de cologne).
Throughout history there have been various methods for extracting fragrances from plants and animals. These include expression, a process whereby the material is squeezed or compressed to release the essential oils. More commonly, the extraction of plant oils is accomplished by steam distillation. This is the method employed for many citrus fruits.
Other methods of obtaining fragrances from flowers and other plants include solvent extraction, in which the material is treated with a volatile substance to yield a solid substance that contains only the oils, or enfleurage, in which the petals are placed between layers of purified animal fat that become saturated with the flower oil. The result is a product called an absolute.
These natural raw materials are blended with additives such as fixatives and diluents to produce a final perfume that is available in many different concentrations. Fragrances from natural sources tend to be less expensive than those produced synthetically.
The initial scent of a perfume is referred to as the top note and it consists of very small molecules that evaporate quickly. Middle notes appear just before the top note disappears and are usually derived from a blend of leaves and flowers. They are generally more complex than top notes and may take up to an hour to be noticed.
Base notes are the deep and rich notes in a perfume. They are generally not noticeable until the middle note has dissipated and can be derived from musk, amber, resins and wood scents. Perfumes also contain diluents that smooth the transition of the other notes in the composition.
Many perfumes are made up of a mixture of these components with the amount of each ingredient determining the intensity and longevity of the perfume. The use of perfume has been a common practice for most people since early prehistoric times and the popularity of this form of personal adornment continues today. However, recent research has shown that some of the chemicals used to create a perfume can cause health problems and environmental degradation. It is therefore important to read the ingredients label when purchasing any perfume or other scented product.