Enzyme-assisted extraction
The release of essential oils from plant cells can be done by the green method of using enzymes. This method is based on the ability of enzymes to catalyze reactions, under moderate conditions in aqueous solutions and provides extraction and release of bioactive compounds. Hence enzyme-assisted extraction method is a technique extraction is considered environmentally friendly (figure 12). The enzymes used can be obtained from bacteria, fungi, animal organs and plant extracts. In this method, important factors such as efficiency, operating conditions such as time, temperature, pH, the ratio of enzyme to substrate and substrate particle size should be considered. The advantages of this method are: low solvent consumption, increased efficiency and quality. One of the limitations of this method is the high relative cost for the process of large volumes of raw materials, enzyme preparation and the problem of converting process scale to industrial scale (due to the complex and different behavior of enzymes in ambient conditions which varies with factors such as dissolved oxygen content, temperature and material availability) [76]. There are 2 routes, to enzyme-assisted extraction: enzyme-assisted aqueous extraction (EAAE) and Enzyme assisted cold pressing (EACP) [77]. Glycosidics essential oils (bitter almond and mustard essential oil) are obtained by enzyme-assisted extraction [19].