A rose is either a woody perennial flowering plant of the genus Rosa, in the family Rosaceae, or the flower it bears. There are over three hundred species and tens of thousands of cultivars. They form a group of plants that can be erect shrubs, climbing, or trailing, with stems that are often armed with sharp prickles. Their flowers vary in size and shape and are usually large and showy, in colours ranging from white through yellows and reds. Most species are native to Asia, with smaller numbers native to Europe, North America, and northwestern Africa. Species, cultivars and hybrids are all widely grown for their beauty and often are fragrant. Roses have acquired cultural significance in many societies. Rose plants range in size from compact, miniature roses, to climbers that can reach seven meters in height. Different species hybridize easily, and this has been used in the development of the wide range of garden roses.
Rose water is a flavoured water made by steeping rose petals in water. It is the hydrosol portion of the distillate of rose petals, a by-product of the production of rose oil for use in perfume. Rose water is also used to flavour food, as a component in some cosmetic and medical preparations, and for religious purposes throughout Eurasia.
Perfume is a mixture of fragrant essential oils or aroma compounds (fragrances), fixatives and solvents, usually in liquid form, used to give the human body, animals, food, objects, and living-spaces an agreeable scent. Perfumes can be defined as substances that emit and diffuse a pleasant and fragrant odor. They consist of manmade mixtures of aromatic chemicals and essential oils. The 1939 Nobel Laureate for Chemistry, Leopold Ružička stated in 1945 that "right from the earliest days of scientific chemistry up to the present time, perfumes have substantially contributed to the development of organic chemistry as regards methods, systematic classification, and theory."
An essential oil is a concentrated hydrophobic liquid containing volatile chemical compounds from plants. Essential oils are also known as volatile oils, ethereal oils, aetheroleum, or simply as the oil of the plant from which they were extracted, such as oil of clove. An essential oil is essential in the sense that it contains the essence of the plant's fragrance—the characteristic fragrance of the plant from which it is derived. The term "essential" used here does not mean indispensable or usable by the human body, as with the terms essential amino acid or essential fatty acid, which are so called because they are nutritionally required by a living organism.
Used in perfumery and aromatherapy, absolutes are similar to essential oils. They are concentrated, highly aromatic, oily mixtures extracted from plants. Whereas essential oils are produced by distillation, boiling, or pressing, absolutes are produced through solvent extraction, or more traditionally, through enfleurage.
Citronella oil is an essential oil obtained from the leaves and stems of different species of Cymbopogon (lemongrass). The oil is used extensively as a source of perfumery chemicals such as citronellal, citronellol, and geraniol. These chemicals find extensive use in soap, candles and incense, perfumery, cosmetic, and flavouring industries throughout the world.
Enfleurage is a process that uses odorless fats that are solid at room temperature to capture the fragrant compounds, such as volatile oils, produced by plants. The process can be "cold" enfleurage or "hot" enfleurage.
Geraniol is a monoterpenoid and an alcohol. It is the primary component of citronella oil and is a primary component of rose oil and palmarosa oil. It is a colorless oil, although commercial samples can appear yellow. It has low solubility in water, but it is soluble in common organic solvents. The functional group derived from geraniol is called geranyl.
Steam distillation is a separation process that consists of distilling water together with other volatile and non-volatile components. The steam from the boiling water carries the vapor of the volatiles to a condenser; both are cooled and return to the liquid or solid state, while the non-volatile residues remain behind in the boiling container.
Nutmeg oil is a volatile essential oil from nutmeg. The oil is colorless or light yellow and smells and tastes of nutmeg. It contains numerous components of interest to the oleochemical industry. The essential oil consists of approximately 90% terpene hydrocarbons. Prominent components are sabinene, α-pinene, β-pinene, and limonene. A major oxygen-containing component is terpinen-4-ol. The oil also contains small amounts of various phenolic compounds and aromatic ethers, e.g. myristicin, elemicin, safrole, and methyl eugenol. The phenolic fraction is considered main contributor to the characteristic nutmeg odor. However, in spite of the low oil content, the characteristic composition of nutmeg oil makes it a valuable product for food, cosmetic and pharmaceutical industries. Therefore, an improved process for its extraction would be of industrial interest.
Supercritical fluid extraction (SFE) is the process of separating one component (the extractant) from another (the matrix) using supercritical fluids as the extracting solvent. Extraction is usually from a solid matrix, but can also be from liquids. SFE can be used as a sample preparation step for analytical purposes, or on a larger scale to either strip unwanted material from a product (e.g. decaffeination) or collect a desired product (e.g. essential oils). These essential oils can include limonene and other straight solvents. Carbon dioxide (CO2) is the most used supercritical fluid, sometimes modified by co-solvents such as ethanol or methanol. Extraction conditions for supercritical carbon dioxide are above the critical temperature of 31 °C and critical pressure of 74 bar. Addition of modifiers may slightly alter this. The discussion below will mainly refer to extraction with CO2, except where specified.
Neroli oil is an essential oil produced from the blossom of the bitter orange tree. Its scent is sweet, honeyed and somewhat metallic with green and spicy facets. Orange blossom is also extracted from the same blossom and both extracts are extensively used in perfumery. Orange blossom can be described as smelling sweeter, warmer and more floral than neroli. The difference between how neroli and orange blossom smell and why they are referred to with different names, is a result of the process of extraction that is used to obtain the oil from the blooms. Neroli is extracted by steam distillation and orange blossom is extracted via a process of enfleurage or solvent extraction.
Myrcene, or β-myrcene, is a monoterpene. A colorless oil, it occurs widely in essential oils. It is produced mainly semi-synthetically from Myrcia, from which it gets its name. It is an intermediate in the production of several fragrances. α-Myrcene is the name for the isomer 2-methyl-6-methylene-1,7-octadiene, which has not been found in nature.
Citronellol, or dihydrogeraniol, is a natural acyclic monoterpenoid. Both enantiomers occur in nature. (+)-Citronellol, which is found in citronella oils, including Cymbopogon nardus (50%), is the more common isomer. (−)-Citronellol is widespread, but particularly abundant in the oils of rose (18–55%) and Pelargonium geraniums.
Nerol is a monoterpenoid alcohol found in many essential oils such as lemongrass and hops. It was originally isolated from neroli oil, hence its name. This colourless liquid is used in perfumery. Like geraniol, nerol has a sweet rose odor but it is considered to be fresher. Esters and related derivatives of nerol are referred to as neryl, e.g., neryl acetate.
Rosa × damascena, more commonly known as the Damask rose, or sometimes as the Iranian Rose, Bulgarian rose, Arab rose, Ispahan rose and Castile rose, is a rose hybrid, derived from Rosa gallica and Rosa moschata. DNA analysis has shown that a third species, Rosa fedtschenkoana, has made some genetic contributions to the Damask rose.
Fragrance extraction refers to the separation process of aromatic compounds from raw materials, using methods such as distillation, solvent extraction, expression, sieving, or enfleurage. The results of the extracts are either essential oils, absolutes, concretes, or butters, depending on the amount of waxes in the extracted product.
Plant oils or vegetable oils are oils derived from plant sources, as opposed to animal fats or petroleum. There are three primary types of plant oil, differing both the means of extracting the relevant parts of the plant, and in the nature of the resulting oil:
- Vegetable fats and oils were historically extracted by putting part of the plant under pressure, squeezing out the oil.
- Macerated oils consist of a base oil to which parts of plants are added.
- Essential oils are composed of volatile aromatic compounds, extracted from plants by distillation.
Attar, also known as ittar, is an essential oil derived from botanical or other natural sources. Most commonly these oils are extracted via hydrodistillation or steam distillation. The Persian physician Ibn Sina was the first to derive the attar of flowers from distillation. Attar can also be expressed by chemical means but generally natural perfumes which qualify as attars are distilled with water. The oils are generally distilled into a wood base such as sandalwood and then aged. The aging period can last from one to ten years depending on the botanicals used and the results desired. Technically attars are distillates of flowers, herbs, spices and other natural materials such as baked soil over sandalwood oil/liquid paraffins using hydrodistillation technique involving a still and receiving vessel. These techniques are still in use at Kannauj in India.
