Experimental study on essential anise star oil purification

Abstract

Vietnam is one of the world’s largest annual anise harvest countries. However, products from anise are mainly in the form of dried anise fruit and crude star anise essential oil with low economic value. The main component of the star anise essential oil is trans-anethole which needs to be purified to produce higher-value products. This study focused on building an experimental system for purifying star anise essential oil by a batch distillation column working at vacuum pressure. The products obtained during the purification process were analysed by gas chromatography-mass spectrometry (GC-MS). Analytical results were used to evaluate the ability to separate volatile impurities in the crude star anise essential oil. Results showed that the bottom temperature of the tower below 150^oC, corresponding to a vacuum pressure of less than 0.1 bar, can reduce the thermal decomposition of essential oils. The volatile components, such as α-pinene, β-phellandrene, limonene, and linalool, were thoroughly separated at the top of the tower.