Fragrance is a mixture of chemicals skillfully assembled by the perfumer and used in a variety of scented products such as cosmetics, hair care and soaps. Its use has been recorded in some of the world’s earliest civilizations; it is widely believed that scent plays an important role in emotional and social interactions. Its pleasant odor may be derived from natural essential oils or artificial compounds. Many people use fragrances to convey a particular mood or message, while others find it helpful in alleviating anxiety and stress. In addition, research suggests that the sense of smell is closely linked to memory, and a number of studies have shown that certain scents can improve mood and even enhance cognitive function.
The term fragnance can also refer to the scent or aroma emitted by a person, or a particular object, such as a piece of clothing. Perfumes, in the strict sense of the word, are liquid preparations that are intended for scenting, and typically contain a mix of natural essences or synthetic materials and fixatives. Perfumes vary by the concentration of the aromatic chemicals they contain, with parfum being the strongest. Until the 19th century, all perfumes were made from natural scents, but synthetic chemicals have become increasingly common.
Fragrances are classified according to the concentration of scent chemicals they contain, and manufacturers typically arrange them into a pyramid structure. The top notes are the lighter odorants that appear closest to the skin, followed by the middle and base notes. The pyramid presentation is not perfect, and it is difficult to make a perfume that is entirely composed of one aromatic chemical (except for vanilla, which is often considered a single scent). Most perfumes contain elements from several families of chemicals.
Most perfumes and colognes contain more than just the fragrance chemicals; they also include solvents, stabilizers, UV-absorbers, preservatives and dyes. The chemicals in a perfume are usually obtained from petroleum or natural raw materials, and the companies that produce them purchase their fragrance mixtures from perfumeries. Fragrance ingredients, whether natural or synthetic, can cause health problems. Regardless of their origin, fragrance chemicals release volatile organic compounds that can contribute to air pollution and damage the skin.
A number of methods are used for extracting the essential oils needed to create a perfume, including distillation and expression. Distillation is the most common, in which the material is heated to high temperatures and condensed into a volatile liquid. The process is aided by the presence of alcohol, which acts as a solvent to separate the desired odorants from other chemicals. Expression is more effective for delicate materials such as fruit rinds and orchids, and involves mechanically squeezing the oils out of the plant material.
Modern perfumery relies largely on chemical synthesis, which allows perfumers to produce aroma chemicals that cannot be found in nature and to reproduce existing smells. For example, calone, a compound of synthetic origin, imparts the fresh ozonous metallic marine smell commonly associated with seawater, and coumarin, which is derived from a naturally occurring substance called vanillin, gives a rich amber-like scent.