The Effect of Pretreatment Type on the Yield of Essential Oils from Eucalyptus Species (Camaldulensis And Torelliana ) Using Steam Distillation

In recent years, the challenge of low yield or inferior physicochemical and phytochemical characteristics of oil during the extraction of essential oils from diverse medicinal plants utilizing different methodologies and pretreatment procedures has been the pivot of many studies. In line with this, the study aims to examine how different pretreatment types affect the production and quality of essential oils extracted from Eucalyptus camaldulensis and Eucalyptus torelliana using steam distillation. The leaves of the two readily available eucalyptus species in Nigeria were first pretreated by chilling at -4°C, airdrying or direct usage as wet leaves and were extracted by indirect steam distillation at a temperature of 100°C and different times of 30-182 min for Eucalyptus camaldulensis and 30-240 min for Eucalyptus torelliana. The results showed that the highest yield of oil was observed for the chilled pretreated leaves for the Eucalyptus camaldulensis (1.4% at 135 min) and Eucalyptus torelliana (1.73%, 224.25 min) with Eucalyptus torelliana showing a higher yield at a longer extraction time. Consequently, the chilled pretreatment enhanced oil release by disrupting the plant cell structure via freezing. This study indicates that pretreatment methods significantly influence the yield and chemical composition of Eucalyptus essential oil derived from Eucalyptus camaldulensis and Eucalyptus torelliana.