Optimisation of distillation process parameters for extraction of Tay Giang citronella essential oil by direct steam distillation method

In Vietnam, there were several research on essential oil extraction from citronella leaves by direct steam distillation. However, most studies focused on the effects of temperature, pressure, and distillation time on essential oil yield, mainly aiming to reduce distillation time with little attention to the chemical composition of the citronella oil obtained. Meanwhile, citronella essential oil contains no fewer than 20 constituents with the 3 most important constituents being citronellal, geraniol, and citronellol. The Vietnamese National Standard 11426:2016 (equal to ISO 3848:2016) regulates the chemical content of Java citronella essential oil for export as citronellal 31-40%, geraniol 20-25%, and citronellol 8.5-14%. The current Java citronella oil often has a citronellol content below 20%, thus failing to meet the standard in ISO 3848:2016. The aims of this research were to optimise the distillation process parameters, including temperature, pressure, and distillation time for extraction of citronella essential oil from Tay Giang citronella by direct steam distillation method in order to maximise yield and maintain geraniol content above 20%. The research results have determined the following optimal technical parameters for the extraction of Tay Giang citronella essential oil: temparature 116±1oC, pressure 1.2±0.05 atm, and distillation time 126±1 min to obtain an essential oil yield of 0.94% with a geraniol content of 20.17%. These results can be used to identify the technology for industrial-scale production of Tay Giang citronella essential oil for export purposes.