Rose oil (rose otto, attar of rose, attar of roses or rose essence) is the essential oil extracted from the petals of various types of rose. Rose ottos are extracted through steam distillation, while rose absolutes are obtained through solvent extraction or supercritical carbon dioxide extraction, with the absolute being used more commonly in perfumery. Even with their high price and the advent of organic synthesis, rose oils are still perhaps the most widely used essential oil in perfumery.
Due to the labor-intensive production process and the low content of oil in the rose blooms, rose oil commands a very high price. Harvesting of flowers is done by hand in the morning before sunrise and material is distilled the same day.
There are three main methods of extracting the oil from the plant material:
- Steam distillation, which produces an oil called rose otto or attar of roses.
- Solvent extraction, which results in an oil called rose absolute.
- Supercritical carbon dioxide extraction, yielding an essential oil that may be marketed as either an absolute or as a CO2 extract.
In the process of distillation, large stills, traditionally of copper, are filled with roses and water. The still is fired for 60–105 minutes. The vaporized water and rose oil exit the still and enter a condensing apparatus and are then collected in a flask. This distillation yields a very concentrated oil, direct oil, which makes up about 20% of the final product. The water which condenses along with the oil is drained off and redistilled, cohobation, in order to obtain the water-soluble fractions of the rose oil such as phenethyl alcohol which are a vital component of the aroma and which make up the large bulk, 80%, of the oil. The two oils are combined and make the final rose otto.
Rose otto is mobile in room temperature and is usually clear, light yellow in color. It will form white crystals at normal room temperature which disappear when the oil is gently warmed. It will tend to become more viscous at lower temperatures due to this crystallization of some of its components.