The extraction processes of garlic oil mainly include: steam distillation, solvent extraction, supercritical extraction, ultrasonic and microwave assisted extraction, etc. Next, three of the extraction methods will be introduced.

Steam distillation method:

The principle is to pass water vapor into an organic substance that is insoluble or hardly soluble in water but has a certain volatility (garlic oil has a certain volatility), so that the organic substance is distilled together with the water vapor at a temperature below 100 ℃ Come out, and then be further separated to obtain a relatively pure substance. The general process of this method is: garlic peeling → washing → mashing with water → enzymatic hydrolysis → steam distillation → oil-water separation → garlic oil.
Steam distillation has the characteristics of simple equipment, low cost and good stability, and is one of the most commonly used methods. However, due to the relatively high fermentation and distillation temperature, the activity of alliinase decreases, allicin is lost, and the oil yield is low. Moreover, the garlic oil obtained has a cooked taste, which is not fresh enough.

Solvent extraction method:

Garlic oil is slightly soluble in water and easily soluble in organic solvents such as ethanol, benzene, and ether. Using this property, garlic oil can be extracted with organic solvents. There is no obvious difference between the garlic oil obtained by this method and the garlic oil obtained by steam distillation. The choice of organic solvent is the key. It is required that the solvent has good solubility for garlic oil, is easy to separate after leaching, has a significant difference in boiling point, and does not contain other unpleasant odors and solvent residues. The general process of the solvent method is: garlic peeling → washing → mashing → enzymatic hydrolysis → solvent extraction → distillation separation → solvent recovery → garlic oil.

Supercritical CO2:

Supercritical fluid extraction technology is a new type of extraction and separation technology. This technology uses the characteristics of fluid in a certain area near the critical point, which has abnormal phase equilibrium behavior and transfer performance with the solute to be separated, and the solute solubility changes with pressure and temperature, and changes in a relatively wide range. A technology to achieve solute separation. Because CO2 is non-toxic and cheap, it is often used as an extractant. The general process of supercritical CO2 extraction of garlic oil is: garlic peeling → washing → mashing → filling the extraction column → sealing → supercritical extraction → depressurization → garlic oil.