Chemical composition and citral content in lemongrass (Cymbopogon citratus) essential oil at three maturity stages

The demand for lemongrass (Cymbopogon citratus) is for its high citral content. Early or delayed harvesting of lemongrass affected essential oil and citral content. The objective of the study was to determine the effects of three maturity stages at harvest of lemongrass on essential oil, chemical composition and citral contents. The lemongrass plant was planted using a randomized complete block design with four replications, at the University Agriculture Park, Universiti Putra Malaysia. The plants were harvested at 5.5, 6.5, and 7.5 months after planting. After harvest, the essential oil, chemical composition and citral contents were analysed using gas chromatography-mass spectrometry (GC-MS) analysis. There were significant effects of maturity stages on essential oil and citral contents. Lemongrass harvested at 5.5 and 6.5 months after planting had significantly higher oil contents than those harvested at 7.5 months. A total of 65 compounds were detected from all the three stages of maturity. However, only 13 compounds were present at each of the maturity stage. Among 13 compounds, only 7 compounds (β-myrcene, 3-undecyne, neral, geranial, nerol, geranyl acetate and juniper camphor) had a concentration of greater than 1%. The citral content at 6.5 months after planting was higher by 11.4% than at 5.5 months after planting. The citral content decreased by 5.4% when lemongrass was harvested at 6.5 compared to at 7.5 months after planting. Citral content peaked at 6.7 ± 0.3 months after planting. Thus, maturity stage at harvest influenced essential oil and citral contents of lemongrass. Therefore, lemongrass should be harvested at the appropriate level of maturity in order to achieve high quality essential oil and lower production cost.   Key words: Geranial, neral β-myrcene, hydrodistillation, freeze dry.