The extraction process of garlic oil mainly includes: steam distillation, solvent extraction, supercritical extraction, ultrasonic and microwave assisted extraction.
The principle is to pass water vapor into an organic substance that is insoluble or insoluble 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 further separation to obtain a more pure substance. The general technological process of this method is: peeling garlic → washing → mashing with water → enzymolysis → steam distillation → oil-water separation → garlic oil.
The steam distillation method 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 temperatures, the activity of alliinase decreases, and allicin is lost, resulting in a lower oil yield. And the garlic oil obtained has a cooked taste, not fresh enough.
Garlic oil is slightly soluble in water and easily soluble in organic solvents such as ethanol, benzene, and ether. Taking advantage of this property, garlic oil can be extracted with organic solvents. There is no obvious difference between garlic oil obtained by this method and garlic oil obtained by steam distillation. The choice of organic solvent is the key. The solvent is required to have good solubility in garlic oil. It is easy to separate after leaching. The boiling point is significantly different. It does not contain other bad smells and solvent residues. The general process of the solvent method is: peeling garlic → washing → mashing → enzymolysis → solvent extraction → distillation separation → recycling solvent → garlic oil.
The extraction method of supercritical fluid extraction technology is a new type of extraction separation technology. This technology utilizes the characteristic that the fluid has an abnormal phase equilibrium behavior and transfer performance with the solute to be separated in a certain area near the critical point, and the ability to dissolve the solute changes with pressure and temperature and changes within a wide range. And 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: peeling garlic→washing→mashed→packing extraction column→sealing→supercritical extraction→pressure reduction→garlic oil.
Ultrasonic extraction has a prominent role in the extraction of natural product active ingredients. Ultrasound can effectively break the cell boundary layer, increase the diffusion speed, at the same time increase the crushing speed, shorten the crushing time, and can significantly improve the extraction efficiency. There is no chemical reaction during the leaching process, and the activity of the bioactive substances to be leached is not reduced.
Microwave is an electromagnetic wave with a frequency ranging from 300 MHz to 300 000 MHz. Under the action of a microwave electric field, polar molecules continuously change their positive and negative directions at a rate of 2.45 billion times per second, resulting in high-speed collision and friction of molecules. High fever. In order to accelerate the leaching speed of allicin and improve the leaching efficiency, many researchers use microwave-assisted extraction, and the results show that the effect is significant.