Perfume is a liquid mixture of fragrant essential oils or aroma compounds, fixatives and solvents used to give the skin, clothing, food, objects and living spaces an agreeable scent. The word comes from the Latin per meaning through and fumum or smoke, which refers to its ancient use as a way of diffusing pleasant smells over large areas. Historically, perfume was also used to protect from disease and infection; seventeenth century physicians treated plague victims by covering them with scented powders.
Traditionally, natural animal and plant oils have been the main source of perfume ingredients. However, these can be expensive and hard to find, because thousands of flowers and plants must be harvested in order to produce a small amount of oil. Moreover, many of the plant oils are endangered because of over-collection or indiscriminate cultivation. The production of natural perfumes can also be problematic for the environment because it requires considerable amounts of water, which may be contaminated with undesirable substances.
Modern perfumes contain from tens to hundreds of ingredients. Among the most important are a variety of odour compounds extracted from flowers, plants, trees and berries, as well as synthetic aromatic chemicals. These can be grouped according to their structural type (alcohols, esters, aldehydes and terpenes).
A typical perfume contains one or more top notes, which are the fresh, volatile odours that are perceived immediately; middle or body notes, which add depth and fullness and a specific aroma; and base or end notes, which provide a warm, solid, long-lasting fragrance. The odours of each group are generally divided into families, which are grouped by one or more identifiable dominant odour. For example, the floral family is characterized by the aromas of jasmine, rose, lily of the valley and gardenia, while the woody group includes the aromatic grass vetiver, or khuskhus, and sandalwood oils.
Other animal secretions, such as castor oil (called castoreum) from beavers; musk from the sperm whale and civet cat; and ambergris from the intestines of a male deer, are often employed to increase the lasting qualities of perfumes by acting as fixatives which slow down the evaporation rate of the more volatile perfume ingredients. Other such fixatives include mosses, resins and coal tar.
Interestingly, certain odours have earned the reputation of being therapeutic because they are believed to trigger specific mood and physiological consequences. For example, odours associated with freshness and cleanliness are thought to promote feelings of vigor and energy, while the scent of rose is believed to calm and relieve anxiety. This type of “aromatherapeutic” effect is thought to be a result of the associative learning of odours with particular emotions and experiences.
Perfumes are widely used in a wide range of personal care products, such as soaps and talcums, facial creams and powders, shaving gels and antiperspirants. They are even added to some foods, such as cheeses and breads, to impart a specific flavour. Moreover, they are used in some industrial settings to mask unpleasant odours or to mark a specific product.