Subcritical water extraction of essential oil from Coriander (Coriandrum sativum L.) seeds

Subcritical water extraction (SWE) is a technique based on the use of water as an extractant, at temperatures between 100 and 374 degree Celsius and at a pressure high enough to maintain the liquid state. As the temperature of liquid water is raised under pressure, the polarity decreases and it can be used as an extraction solvent for a wide range of compounds. The application of SWE in the extraction of essential oil from coriander (Coriandrum sativum L.) seeds was studied. Ground coriander seeds (3-4 g) were subjected to SWE with water for an extraction time of 15 min under several extraction conditions (pressures of 870 and 1000 psi and temperatures of 65, 100 and 150 degree Celsius). The SWE method was compared with hydro distillation performed by treating 10 g of ground coriander seeds with 100 mL of water for 3 hours. Compounds were removed from the aqueous extract with hexane and determined by gas chromatography mass spectrometry (GC-MSD). It was found that the efficiency (g oil/ g of coriander) of SWE was higher than that provided by hydro distillation with reduced extraction time. The major compounds found were linalool, isoborneol, citronellyl butyrate and geraniol. SWE method has the possibility of manipulating the composition of the oil by varying the temperature and adjusting the pressure. (author)