SOLVENT-FREE MICROWAVE EXTRACTION OF ESSENTIAL OIL FROM CITRUS LIMON (LISBON VARIETY

In this research, solvent-free microwave extraction (SFME) of lemon essential oil was studied using fresh Citrus limon (lisbon variety) peel as raw material. The results of SFME and HD were compared in terms ofextraction time, extraction yield, chemical composition, physical constants (refractive index, density, and color),and cost of the operation. To reach the extraction temperature and obtaining the first essential oil droplet, it isnecessary to heat for only 3 min for SFME compared with 23.0 min for HD. In SFME, large amounts of interiorheating resulted in increased moisture vapor generation inside the sample which created high interior pressure and concentration gradient. Also, scanning electron microscopy of Citrus limon peel undergone HD and SFME provided evidences of more rapid opening of essential oil glands treated by SFME. Extraction of essential oils from Citrus limon peel with SFME was better in terms of energy saving (0.25 kWh for SFME vs. 0.67 kWh for HD), total extraction time (15 min for SFME vs. 120 min for HD), andessential oil yield (1.36±0.06% for SFME vs. 1.22±0.14% for HD). Regarding environmental impact, the calculated quantity of CO2 rejected in the atmosphere is higher in the case of HD (436.72 g CO2/g of essential oil) than that of SFME (147.06 g CO2/g of essential oil). Although there were no significant differences among physical constants of extracted essential oils, but the color of the essential oil extracted by SFME was lighter.Using GC/MS, components of extracted essential oils were identified. The major component of essential oilsextracted by both methods was limonene (58.58±4.14 for SFME vs. 63.15±4.47%, respectively). Such advantages can make SFME as an excellent and environmentally friendly alternative essential oil extraction method from fresh samples.

کلیدواژه ها:

Essential oil composition ، Solvent-free microwave extraction ، Hydrodistillation ، Scanning electron microscopy ، Lisbon lemon