Concretes are produced mainly from flowers (rose, jasmine, tuberose, jonquil, ylang-ylang, mimosa, boronia, etc.), but also from other plant materials (lavender, lavandin, geranium, clary sage, violet leaves, oak moss, etc.). A yield of ca. 0.3 % based on the starting flower material, is obtained in the production of jasmine concrete.
Fresh plant material is extracted with nonpolar solvents (e. g., benzene, toluene, hexane, petroleum ether). On evaporation of the solvent, a semi-solid residue of essential oils, waxes, resins and other lipophilic (oil-soluble) plant chemicals remains.
Because of the heavier nonvolatile compounds (waxes, resins), concretes are only partially soluble in ethanol. Therefore, they are of limited use in perfumery, but they can be employed for scenting soaps.
The concrete may be extracted with ethanol to produce an absolute.
- Karl-Georg Fahlbusch; et al. (2007), "Flavors and Fragrances", Ullmann's Encyclopedia of Industrial Chemistry (7th ed.), Wiley, p. 83