Subcritical CO2 extraction of floral fragrance from Quisqualis indica

Quisqualis indica syn. Q. Densiflora, family Combretaceae, is a large woody, scandent shrub. The composition of the floral extract of Q. indica with subcritical CO2 is compared with that of extracts obtained by different conventional methods such as distillation with water and extraction with pentane. Absolutes obtained by fractionation of the pentane extract (concrete) with cold methanol and subcritical CO2 also are compared. The compounds of these extracts are identified by GC/MS and percentage compositions are determined by GC-FID. The essential oil contains several components, which are responsible for its top note, but some are quite different from those present in the pentane extract. The concrete contains more than 50% of waxy components. The addition of methanol and chilling separated the waxy components only partially from the fragrance components. It is found that the CO2 method of fractionation of pentane extract is a practical process providing an organoleptically superior product, though the later is not still totally free from waxes. The subcritical CO2 extract of flowers contains the desirable odoriferous compounds with lower amounts of waxy substances and is organoleptically superior. The major components detected in the extracts are E- and Z-linalool oxides (furanoid form), 2,2,6-trimethyl-6-vinyl-3-keto-tetrahydropyran, 2,2,6-trimethyl-6-vinyl-3-hydroxy-tetrahydropyran (linalool oxide pyranoid form), (E,E)-α-farnesene, Z-3-hexenyl benzoate and benzyl benzoate and a tentatively identified compound quinoline carbonitrile along with some waxy components.