Solvent-free Microwave Extraction and Composition of Cinnamon Essential Oil
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Abstract:
A solvent-free microwave extraction (SFME) process was optimized to extract cinnamon essential oil, and the components of the extract were analyzed by gas chromatography/mass spectrometry. The in vitro antioxidant capacity and surface micromorphology of the cinnamon essential oil extracted by SFME were also examined and compared with those of cinnamon essential oil extracted by steam distillation (SD). Using the oil yield as an indicator, the optimal extraction conditions were obtained by conducting orthogonal tests. The conditions are as follows: extraction time, 60 min; microwave power, 450 W; moisture content, 60%; and infiltration time, 2.5 h. The essential oil yield under these conditions was 3.15%, which is 35.78% higher than that of the traditional SD. Gas chromatography/mass spectrometry was used to analyze the composition of the extracted cinnamon essential oil, and the results were verified using mass spectrum library and retention indexes. In total, 24 compounds were identified. The main components include cinnamaldehyde (67.69%), eugenol (11.36%), linalool (4.26%), and limonene (2.40%). The cinnamaldehyde and limonene content in the cinnamon oil extracted by SFME was 14.49% and 34.51% higher, respectively, than that extracted by SD, indicating that the cinnamon oil extracted by SFME has superior pharmacological activity. The SEM results suggest that the solvent-free microwave extracted cinnamon essential oil has distinct voids and many irregular cavities. The IC50 values for DPPH (2.10 mg/mL) and hydroxyl free radicals (0.17 mg/mL) in the cinnamon oil extracted by SFME are higher than those for the cinnamon oil extracted by SD. In summary, SFME is a suitable method for extracting cinnamon essential oil because high extraction efficiency, high oil yield, and excellent oil quality can be achieved using this method.
