| چکیده انگلیسی مقاله |
Background and objectives: Malus domestica Borkh. ‘Red delicious’ is one of the most economically significant fruit crops cultivated worldwide, including in Iran, with its aroma arising from a complex mixture of volatile compounds that define its sensory profile and vary across species and cultivars. Deep eutectic solvents (DESs) represent an innovative class of solvents distinguished by their non-flammability, negligible volatility, low vapor pressure, thermal stability, biodegradability, minimal toxicity, and reusability, excelling in extracting bioactive compounds while preserving their structural and functional integrity while also serving dual roles as reaction media and catalysts in organic synthesis to enhance bioavailability. Headspace single-drop microextraction (HS-SDME) is a highly efficient technique for analyzing volatile and semi-volatile compounds, eliminating matrix interference with minimal solvent use, making it ideal for essential oil extraction.
Methodology: This study developed an HS-SDME method for extracting apple essential oils using newly designed DESs, followed by GC/MS analysis, with key parameters, including DES composition, drop volume, sample weight, extraction temperature, and time, systematically optimized, evaluating three DESs composed of choline chloride paired with ethylene glycol, phenol, or 4-chlorophenol as hydrogen bond donors, and comparing the results with conventional hydrodistillation (HD) using a Clevenger apparatus.
Results: Among the tested solvents, the combination of choline chloride and 4-chlorophenol demonstrated the highest extraction efficiency for the target analytes. Several experimental parameters influencing the efficiency of essential oil extraction using the DESs-HS-SDME method were optimized as follows: a eutectic solvent volume of 3 mL, an extraction time of 50 minutes, an extraction temperature of 80 °C, and a sample weight of 3 g. Using the DESs-HS-SDME method, 22 compounds were isolated from apple essential oil, consistent with the results obtained from the HD method. Of these compounds, 76% were monoterpenes, including α-thujene, α-pinene, camphene, sabinene, β-pinene, myrcene, α-phellandrene, p-cymene, β-phellandrene, Z-β-ocimene, E-β-ocimene, γ-terpinene, terpinolene, α-pinene oxide, trans-sabinene hydrate, cis-verbenol, neo-3-thujanol, carvacrol ethyl ether, and terpinen-4-ol acetate. Additionally, 20% were sesquiterpenes, comprising bicyclogermacrene, (E,E)-α-farnesene, germacrene B, spathulenol, and epi-cedrol. Notably, α-phellandrene, α-pinene, β-pinene, sabinene, and p-cymene were the most predominant compounds in both analytical methods employed.
Conclusion: In this study, an analytical procedure was proposed for the first time for extracting essential oil from apple fruit using headspace single-drop microextraction (HS-SDME) with deep eutectic solvents (DESs). Unlike previous studies, which employed conventional solvents for HS-SDME, this work introduces DESs as a greener and more effective alternative. The DESs-HS-SDME method provides an environmentally friendly, simple, and efficient approach for essential oil extraction from apple fruit. Given their low toxicity, biodegradability, and tunable properties, DESs show great promise as suitable extraction media for isolating volatile compounds from natural samples using HS-SDME. |