Chemical composition and citral content of essential oil of lemongrass (Cymbopogon citratus (DC.) Stapf) leaf waste prepared with various production methods

Lemongrass ( Cymbopogon citratus ) is a valuable commodity, serving as a major source of essential oil in the food and non-food sectors, including cosmetics and pharmaceuticals. In this context, citral content is important to lemongrass essential oil quality. Despite the higher citral content found in leaves compared to other plant parts, studies addressing lemongrass essential oil produced from waste leaves of the harvesting process have yet to be conducted. Therefore, this research aimed to determine lemongrass ( Cymbopogon citratus (DC.) Stapf) leaf waste essential oil's bioactive components, citral content, and yield using various raw material pretreatments and distillation methods. The various raw materials pretreatment used in this study were fresh, room temperature drying for 48 h, and cabinet dryer drying at 70 o C for 5 h. The methods of distillation used were water distillation and water steam distillation techniques. According to the GCMS test, the major components in lemongrass leaf waste essential oil are E-citral, Z-citral, and β-myrcene. Oxygenated monoterpenes are the most abundant compound group in lemongrass leaf waste essential oil, followed by monoterpene hydrocarbons dominated by β-myrcene as well as minor compound groups such as monoterpenoids, sesquiterpene hydrocarbons, and ketones. The results show that raw material pretreatments and distillation methods significantly affect the Z-citral, E-citral, and total citral yield but have no significant effect on Z-citral, E-citral, and total citral content. Water steam distillation and fresh raw materials are the selected methods with the highest citral yield of 0.67 ± 0.05 %. The test on the quality characteristics of selected lemongrass leaf waste essential oil, including specific gravity, optical rotation, refractive index, and solubility in 70 % ethanol, shows conformity with ISO-3217-1974 standards. • Essential oil was extracted from lemongrass ( Cymbopogon citratus (DC.) Stapf) leaf waste. • The pretreatments and distillation methods significantly affect the citral yield. • The major components are E-citral, Z-citral and β-myrcene. • Fresh raw materials and water steam distillation are the selected methods.