Enhancing Yields and Antioxidant Activities of Caraway Seeds Essential Oil by Ultrasonic Treatment Combined with Hydro-distillation, and Microwave-assisted Hydro-distillation

Abstract

This study examined the effects of ultrasonic treatment on the amount and quality of essential oils extracted from caraway seeds using ultrasonic treatment followed by hydro-distillation and ultrasonic treatment followed by microwave-assisted hydro-distillation. Afterward, the obtained results were compared with those of untreated extracts issued from conventional hydro-distillation and microwave-assisted hydro-distillation. The essential oil yields ranged from 1.18 ± 0.09 to 1.36 ± 0.09% w/w, depending on the extraction technique. Analysis by gas chromatography coupled with mass spectrometry showed the presence of 21 compounds in all the extracts. Produced essential oils consisted of 9.65 ± 1.742 % to 18.59 ± 1.377 % monoterpenes hydrocarbons and 77.20 ± 2.847 to 84.60 ± 1.909 % oxygenated monoterpenes. The main components were limonene and carvone, but the amounts of each component depend on the methods. Additionally, the antioxidant activity of caraway seeds essential oils was determined using the DPPH (2,2-diphenyl-1-picrylhydrazyl) assay. The antioxidant ability of the examined oils was moderate, and the USMAHD oil median inhibitory concentration (IC50) value was the lowest. Moreover, a statistical investigation paved the way for a possible correlation between the carvone/limonene ratio and IC50. Consequently, this aspect, which is the potential for improving the extract’s quality by modifying the ratio of the target components known for their high antioxidant effects, made this study novel.