Evaluation Of Stability Of Eucalyptus Globulus Essential Oil In Nanoemulsion System Created By Phase Inversion Temperature Method

Abstract

Eucalyptus Globulus oil with high pest control property is a powerful material for green pesticide. Eucalyptol (1,8-cineole) is known as the main active ingredient in E. Globulus oil, have strong insect repellent properties. Nanoemulsion system is a best carrier system to overcome several drawbacks of essential oil in biopesticide including low aqueous solubility, susceptibility to volatilization, photodegradation and instability when storing over a period of time. However, the stability of nanoemulsions is quite fluctuated over time that can affect the pesticidal property of products. Therefore, this research was conducted to investigate the stability of eucalyptus essential oil in nanoemulsion system over time and the effect of some factors including storage temperature, the addition of co-surfactant and the co-existence of E. Globulus oil and Neem oil on the stability of the system. These findings suggested that 4oC is the best storage condition which can minimize the effect of some main destabilization mechanism such as coalescence and Ostwald ripening up to 60 days. The obtained results from the study of co-surfactant on the stability of the system showed that 1.6% of sorbitan monooleate (Span 80) is an appropriate concentration which makes the system stable during 60 days and retains 7601 mg/L Eucalyptol in the system after 90 days, higher than that in the system without the addition of Span 80. Higher concentration of Span 80, at 2% and 2.7%, made the system become broad in size distribution only after 15 days while phase separation was observed at 4% of Span 80 after preparation. Regarding the co-existence of Neem oil and E.Globulus oil, a complex interaction between them in nanoemulsion system was observed. Oil was encapsulated at maximum level (18%) in the formulations consist of 20% of Neem oil. At higher percentage of Neem oil (50% and 62.5%), the oil loading capacity of the system decrease to 14% and 12%, respectively.