Native to Central America (mainly Mexico) where it grows wild; commercially cultivated in southern France (Grasse), Morocco, Taiwan, Egypt, India, Indonesia, and the Comoros Islands. Polianthes tuberosa is a stately perennial that grows to a height of 3 feet with long slender leaves, a tuberous root and a tall central spike topped with large, very fragrant white flowers. The single-flowered (highly fragrant) variety is grown for the extraction of its oil, while the double-flowered (less fragrant) variety is grown for the cut flower industry.
The more costly and time-honored method of enfleurage of oils (developed commercially in the 17th century), requiring highly specialized personnel and equipment, is still used today to extract the aromatic oils from Tuberose (and only one other flower jasmine). This procedure is considered advantageous because both flowers hold their aroma after harvesting critical for the enfleurage process and the cost of extraction is offset by the fact that the oil yield is much greater than the yield via solvent extraction (described in the following paragraph). One is fortunate indeed when the precious enfleurage of Tuberose, rare and costly, is obtained! Oil extraction using a solvent occurs as quickly as possible after harvest in a two step process. Giant receptacles, usually copper or stainless steel, are filled with tuberose blossoms and a solvent, most often hexane, in a manner that allows the solvent to be readily and continually in contact with each blossom. At the end of this process, the removal of the solvent by evaporation yields a waxy, aromatic mass called the concrete. The second stage of extraction is the process of washing the concrete in large amounts of alcohol. Removal of the insoluble waxy substances that separate out when the alcoholic solution is chilled is followed by removal of the alcohol via evaporation, leaving us with the beautiful aromatic plant oils known as absolutes. Although removal of the solvent and alcohol is as complete as possible (they are re-usable and therefore the more thorough the recovery, the more practical), there will always be traces of these materials in the absolute. Sometimes a certain small percentage of alcohol is intentionally retained in order that the end product is pourable and more easily used.
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