Chemical-profile variations in essential oils isolated from lemongrass (Cymbopogon flexuosus) biomass and condensate wastewater by re-distillation and solvent extraction techniques

Abstract

During steam/hydro-distillation of aromatic crops, a small hydrophilic essential oil fraction escapes into the condensate wastewater. Lemongrass [Cymbopogon flexuosus (Nees ex Steud.) Wats.] condensate waste water obtained after distilling the biomass and collecting the essential oil was subjected to re-distillation and liquid-liquid extraction with n-hexane and ethyl acetate to isolate the dissolved aromatic oil. GC-FID, GC-MS analyses of these oils led to the identification of thirty-seven constituents comprising mostly oxygenated monoterpenes (78.3–90.7%). Neral (35.1%) and geranial (44.3%) predominated in the lemongrass biomass essential oil. 6-Methyl-5-hepten-2-one (7.3–32.9%), neral (26.7–32.9%) and geranial (24.9–33.9%) are the major constituents of the recovered aromatic oils which can be used for isolating citral (51.6–66.8%), for application in cosmetics, botanical pesticides and aromatherapy. The essential oil isolated by re-distillation can serve as a new source for isolation of 6-methyl-5-hepten-2-one (32.9%). Solvent-extracted aromatic oils contained higher amounts of citral (neral + geranial) (62.9–66.8%) relative to re-distilled essential oil (51.6%).