Extraction and encapsulation of lesser galangal (Alpinia officinarum) essential oil using microwave pretreatment and spray drying

Abstract

Galangal (Alpinia officinarum) essential oil potentially exerts several health benefits such as antiproliferative, pain relief and fever reduction activities. The essential oil in this study was extracted using the microwave (MW) assisted treatment as an alternative method to conventional extraction. The samples were treated with MW at different power levels (600, 700, and 800 W) for 3 min before subjecting to a hydro distillation extraction. The effect of sample:water ratio (1:1 and 1:0.5) was also investigated. The MW treatment at 600 W and sample:water ratio of 1:1 resulted in the highest amount of essential oil (0.33%). The MW pretreatment had a positive effect on reducing the extraction time (from 3 h to 2.5 h) observed at all MW power levels. The effect of essential oil loading capacity (10, 20 and 30%) on the encapsulation yield was evaluated. The in vitro antioxidative activity of the obtained powder was then measured. The highest encapsulation efficiency (86.5%) was obtained from the 20% loading capacity, suggesting for a suitable amount of essential oil should be loaded for the encapsulation. The in vitro antioxidant activity of the encapsulated essential oil powders was determined. The IC50 of the powder was 2077 μg/mL using DPPH assay