Evaluation of yield and quality of essential oils from Eucalyptus globulus leaves

Abstract

Essential oils are a diverse set of natural products that are important sources of flavoring chemicals and aromatics in pharmaceutical products, food and the perfume industry. The oil is produced in different parts of the plants and contains various chemical compounds that give plants a characteristic odor and flavor and offer protection from pests, predators, attraction of pollinators and seed dispersal. These compounds, yield and the efficacy of essential oils vary between different plant species and also within plants of the same species. However, limited studies have been carried out to investigate the impact of some factors like age of the tree and sample collection time on the yield and quality of E. globulus leaves. This study evaluated the yield and chemical composition of essential oils extracted from Eucalyptus globulus leaves, focusing on the influence of tree age and sample collection time on the yield and chemical composition. Leaf samples were harvested from trees of 2 and 4-5 years at two different times: before 7:00 AM and at 1:00 PM. Essential oils were extracted using hydro-distillation using the Clevenger apparatus and analyzed for their chemical composition using Gas Chromatography-Mass Spectrometry (GC-MS). The oil was collected in glass amber bottles and weighed to determine the weight. Statistical analysis using two-way ANOVA revealed that both age and sample collection time had a significant effect in oil yield where P < 0.001 and F values were 293.15 and 163.17 respectively. The 2 years 7AM samples gave the highest oil yield (1.07%) and the lowest yield was obtained in the afternoon sample collected at 2PM (0.58%). The morning samples showed a slightly higher proportion of 1,8-cineole (25.33%) compared to afternoon samples (23.53%). These results highlight the importance of tree age and sample collection time for improving yield and quality of the essential oil. Further studies can be carried out on routine chemical screening to monitor oil quality and adjust harvesting practices and developing a sustainable harvesting cycle that balances biomass recovery and oil output.