Allicin is an organic sulfur compound extracted from the bulb (garlic head) of Allium in Alliaceae, and also exists in onion and other Alliaceae plants. Its scientific name is diallyl thiosulfinate, and its chemical formula is C6H 10OS2. The solid agent is white to light yellow flowing powder, and the liquid agent is light yellow to brown volatile oily liquid with strong garlic smell, which decomposes during distillation and forms oily precipitate when the aqueous solution is placed. Insoluble in glycerol, propylene glycol, etc., but mixed with ethanol, chloroform, ether and benzene. Unstable to alkali, stable to acid. The solution quickly fails when it is heated. Allicin has inhibitory and bactericidal effects on various cocci, pertussis bacilli, diphtheria bacilli, dysentery bacilli, typhoid and paratyphoid bacilli, Escherichia coli, tuberculosis bacilli, etc. It can inhibit fungal infection; It can also inhibit and kill amoeba, trichomonas vaginalis and pinworm.

The main extraction methods of allicin are as follows: steam distillation, organic solvent extraction and supercritical CO2 extraction. The main effective components obtained by each method are different, and all have their own advantages and disadvantages.

Steam distillation method

The principle of steam distillation is that steam is introduced into organic substances that are insoluble or insoluble in water but have certain volatility. By using the volatility of garlic oil, garlic oil is distilled with steam at a temperature below 100℃, and then purified substances are obtained by further separation. The main components of garlic oil obtained by this method are small molecular thioether compounds such as allyl trisulfide and allyl disulfide. The garlic essential oil was extracted by steam distillation, and the garlic essential oil in the distillate was extracted by refined vegetable oil, so that the allicin content in garlic oil and the quality of garlic oil were improved and the extraction cost was reduced. The content of allicin increased when the distillation temperature was below 80℃ by vacuum steam distillation.

Organic solvent extraction method

Garlic oil is slightly soluble in water, but easily soluble in organic solvents such as ethanol, ethyl acetate and ether. Using this property, garlic oil can be extracted with organic solvents. The choice of solvent is very important, which not only needs good solubility in garlic oil, but also needs its low boiling point and easy separation from garlic oil. At the same time, the solvent should be nontoxic, odorless and low in residue. The advantage of ethanol extraction method is that the temperature of soaking and vacuum distillation is not high, and ethanol can stabilize allicin, and the content of allicin is high. The main component obtained by this method is allicin. Using ethanol as solvent to separate and extract allicin, the optimum technological parameters were determined as follows: the extraction rate of allicin was 0.24%. Using microwave-assisted extraction of allicin, the comparative experiment of extracting allicin with ethyl acetate and ethanol was made. The extraction rate of ethanol was over 0.2%, while the extraction rate of ethyl acetate was less than half of that of ethanol.

Supercritical CO2 extraction

Slight changes in the temperature and pressure of the fluid at the critical point will cause great changes in the solubility of the fluid. By using the influence of pressure and temperature changes on the solubility of the supercritical fluid, the supercritical fluid will contact with the substance to be separated, so that it can selectively extract one of its components. Then, the supercritical fluid will be turned into ordinary gas by depressurizing and heating, and the extracted substance will be completely or basically precipitated, thus achieving the purpose of separation and purification. CO2 is often used as an extractant because of its mild operating conditions, non-toxicity and low price. The advantage of this method is that the extraction yield is higher than that of organic solvent extraction, but the disadvantage is that the required equipment investment is large, the production efficiency is low, and the industrial production has not been realized. Garlic essential oil was extracted by supercritical CO2 extraction, and compared with solvent extraction and steam distillation. The garlic essential oil with higher relative content of allicin was obtained by supercritical CO2 extraction, which was obviously higher than that by solvent extraction and steam distillation. Supercritical CO2 extraction was an ideal method to extract garlic essential oil. In the extraction process of garlic oil, the content of allicin reached 60.54% by combining alcohol extraction with supercritical CO2 extraction, which was higher than that by supercritical CO2 extraction alone.

compound

Adding a specified amount of water and sodium thiosulfate, heating to 40℃, stirring for 30min, dissolving, then dropwise adding chloropropene, controlling the reaction temperature at 40-50℃ until about 1h is finished, keeping the internal liquid at 50-60℃, keeping the temperature for 5 hours, and cooling to room temperature. Then sodium sulfide solution was added dropwise, and the reaction temperature was maintained at 24 ~ 30℃ about 1h, and the mixture was continuously stirred for 30min. After the reaction, petroleum ether extracted the light yellow oil on the upper layer.

Eating too much raw garlic may stimulate oral mucosa and gastrointestinal mucosa, causing dry mouth, bad breath, abdominal pain, diarrhea and other symptoms. Therefore, people who like to eat garlic must pay attention to moderate consumption.

In addition, people who are allergic to garlic should pay attention to avoid eating both raw garlic and cooked garlic. People with oral ulcer, glossitis, gastric ulcer and other diseases should also avoid eating raw garlic, so as not to aggravate the irritation of oral or gastrointestinal mucosa and induce pain.

for reference only