Assessing properties of acantholippia deserticola (Phil.) moldenke essential oil: Comparison between hydrodistillation and microwave-assisted hydrodistillation extraction methods

Acantholippia deserticola (Rica-Rica) is a native shrub of the Chilean highlands used as a medicinal plant and food dressing. The objective of this study was to compare the physical, antioxidant and antimicrobial characteristics of its essential oil (EO), based on the process parameters and extraction methods using hydrodistillation (HD) and microwave-assisted hydrodistillation (MAHD), and assessing presence of fatty acids. The process performance as well as the colour parameters, refractive index, fatty acid profile, antioxidant activity and antimicrobial activity were evaluated. The best process conditions for HD were 90 min, 420 W and 150 g 1000 mL–1; for MAHD, these were 90 min, 700 W and 200 g 1000 mL–1, with yields of 0.45 and 0.49 mL 100 g-1 and antioxidant capacities of 2.38 and 3.92 µmol Trolox g-1 respectively. The collection season, extraction method and its parameters affected the yield and fatty acid profile, influencing EOs’ activity. In terms of mass of herbs, process time as well as energy efficiency and environmental impact, the extraction of MAHD was 8% more efficient. EOs extracted by both methods show a slight inhibitory effect on Streptococcus sp. and Bacillus cereus, and MAHD EO showed a highly inhibitory effect on Streptococcus Group A. The type of extraction method and the process parameters could be set to obtain suitable EOs according to its potential industrial application.