Biotechnology for the production of essential oil
As mentioned in the previous sections, volatiles are natural compounds that have gained commercial interest due to their flavor and fragrance properties. The concentration of the most desirable volatiles in essential oils is very low, about less than 10% (sometimes even less than 1%) [116]. Plant essential oils are usually obtained through extraction intact plants [117] such as distillation, solvents, carbon dioxide, and etc. or by the methods of chemical synthesis. Each of them has its drawbacks. Chemical synthesis often leads to the production of a mixture of products that have an approximate natural flavor quality. Also, this method is not one of the natural and environmentally friendly [116]. Common extraction methods, in addition to being costly, have problems such as: weather conditions including monsoon, drought, or even by volcano, supply shortages, natural disasters, plant diseases, low yield and etc. [117, 118]. Therefore, due to the limitations and disadvantages of methods of extraction from intact plants or chemical synthesis, scientists are trying to move their way to biotechnology methods and make a variety of plant compounds by microorganisms. In the new biotechnology method which is a kind of green method, in addition to being environmentally friendly and no contamination of the process, there are no more problems mentioned and the product is obtained with very high efficiency and quality. Production of natural products and volatile through biotechnology can be an appropriate response to consumer demand in relation to the consumption of natural products and move towards ”green processes” and environmentally friendly. One of the major applications of biotransformation is the production of biotechnology products that are usually synthesized by chemical methods. Bio-methods include volatile production through tissue and cell cultures, hairy roots cultures, culture of microorganisms, biotransformation, metabolic engineering. Various biotechnological methods for the production of volatiles are discussed below: