ROSE BENGAL

Rose grows as a plant, shrub, bush or thicket. The flowers exhibit a five-petal calyx and a multiple five-petal corolla. Like the corolla, the seeds are inserted in the calyx. The plant is of Asiatic origin. Countries where rose is extensively cultivated for extractive purposes include Bulgaria, Turkey, Morocco, France and Italy. The parts used are the flowers, buds, leaves and fruit (hips). Rose has a deep, warm, rich rose odor with a slightly bitter, sharp flavor at high concentrations; pleasant on dilution. The fragrance of the rose flower, captured by extraction, is one of the most valuable flavor and fragrance products used. The most common aroma concentrates of rose are rose oil and rose water, derived from steam distillation; and rose concrete and rose absolute from solvent extraction. Of these, rose oil and rose concrete are produced in the largest quantities.
The choice of rose derivatives for flavor application is often determined by the feasibility of introducing water-soluble β-phenethyl alcohol into the flavor complex. This component is present in large quantities in the extracts; it is almost absent in distillates and may, therefore, have a significant effect on the resulting aroma

The main constituents of rose derivatives include linalool, β-phenethyl alcohol, l-citronellol, nerol, geraniol, eugenol, aldehydes, esters and stearopten (paraffins).

This biological stain can be purified by chromatography on silica TLC using a 35:65 mix of EtOH/acetone as eluent. [Beilstein 19 II 261, 19 III/IV 2926.]