Application of molecular distillation apparatus in essential oil processing and aromatherapy

The application of molecular distillation in the processing of essential oils Plants and their extracts have been used since ancient times to eliminate pain, heal wounds and kill bacteria, thereby achieving therapeutic and health effects [2].

In the 17th century, before modern medicine was formed, the understanding and utilization of plant essential oils was already relatively developed, and about 60 essential oils were used in spices and medical fields at that time[3].

After the 8th century, due to the development of organic chemistry, people have made great progress
in the extraction and composition analysis of plant essential oils.

But more mature synthetic drugs have replaced plant essential oils, although pharmacists have removed essential oils from the shelves, but with the continuous expansion of the scope of natural spice applications, the spice industry has developed dramatically, and natural spice cultivation and extraction techniques have also been continuously improved
.

In addition to the traditional methods of pressing, steam distillation, solvent extraction and other traditional methods continue to develop on a large scale, some emerging extraction and separation methods, such as supercritical extraction technology, ultrasonic technology, microwave technology, etc.
, continue to inject new vitality and vitality into the ancient essential oil industry, and solve practical problems
in production and market.

Molecular distillation technology, as a mature downstream treatment technology, can separate the components of economic value and medical value in essential oils, and remove the components introduced by the essential oil itself or the processing process that endanger human health and reduce the use value, so that the essential oil can be accepted by more people and play a greater role
.

1 Enriching fragrance substances and medicinal ingredients Plant essential oil chemical composition is quite complex, is a class of biologically active chemicals, such as aldehydes, alcohols, ketones, phenols, alkenes, monoterpenes, biterpenes and sesquiterpenes, etc.
, these compounds have low boiling point and volatile characteristics
.

With the application and improvement of capillary gas chromatography technology, the research on essential oils has become more and more in-depth
.

An essential oil can identify dozens, or even hundreds of chemical components, some of the content of the ingredients are also identified, many of which have great economic value of the ingredients, of which the fragrance substances and medicinal ingredients have sterilization, anti-inflammatory, antispasmodic, stimulating, soothing, regulating endocrine and other functions, constitute the basis of the efficacy of aromatherapy, selective extraction and enrichment of these ingredients is the process of increasing the commercial value of
products.

An understanding of the chemical composition of fragrance substances in plant essential oils, such as volatility, solubility, thermal stability, and chemical reaction properties, helps to select the right method for purification and processing
.

The components in most essential oils have poor thermal stability, complex molecular weight and polarity composition, and the use of conventional distillation or solvent methods can easily cause component loss, destruction or bring about sensory-affecting solvents
.

The application of molecular distillation can overcome the above defects and achieve non-destructive separation
of the target substance.

For example, it is used for the separation of myristic acid and irisone in iris root purification oil[4], patchouli oil, cinnamon oil, star anise oil, and mountain cane oil for refining and purification (Table 1) [5,6,7,8].


Molecular distillation can also be used for the extraction of synthetic or semi-synthetic fragrance substances or active ingredients, such as eucalyptin from the reaction of terpineol with acids[9], and the insecticidal synergist piperine of pyrethroid pesticides after catalytic hydrogenation, chloromethylation and etheration [10].