阅读说明：本技术 一种大蒜精油的制备方法 (Preparation method of garlic essential oil ) 是由 朱颖秋 王鹏 钟斌 王庚申 于 2020-12-25 设计创作，主要内容包括：本发明提出一种大蒜精油的制备方法,属于精油制备领域,能够解决现有提取工艺存在能耗高,废水排放量多,大蒜精油收率低等的技术问题。该制备方法包括：1)鲜蒜汁制备；2)鲜蒜汁转化；3)大蒜精油前体制备；4)大蒜精油前体吸附；5)大蒜精油制备。利用本发明提供的制备方法不仅能有效减少蒸发量,还能制得纯度高、品质优异的大蒜精油产品,本发明能够应用于大蒜精油制备方面。(The invention provides a preparation method of garlic essential oil, belongs to the field of essential oil preparation, and can solve the technical problems of high energy consumption, high wastewater discharge, low garlic essential oil yield and the like in the existing extraction process. The preparation method comprises the following steps: 1) preparing fresh garlic juice; 2) converting fresh garlic juice; 3) preparing a garlic essential oil precursor; 4) adsorbing the precursor of the garlic essential oil; 5) preparing garlic essential oil. The preparation method provided by the invention can effectively reduce the evaporation amount, and can also prepare the garlic essential oil product with high purity and excellent quality.)

1. The preparation method of the garlic essential oil is characterized by comprising the following steps:

preparing fresh garlic juice: peeling and cleaning fresh garlic, pulping in a solvent, performing enzymolysis by adopting an enzymolysis method, and filtering to obtain fresh garlic juice;

conversion of fresh garlic juice: adding exogenous alliin into the fresh garlic juice, and performing conversion treatment on the fresh garlic juice to obtain fresh garlic juice rich in allicin;

preparing a garlic essential oil precursor: adsorbing the fresh garlic juice rich in allicin by using a macromolecular adsorbing material, eluting and recovering the adsorbed macromolecular adsorbing material to obtain a garlic essential oil precursor;

adsorption of garlic essential oil precursor: adsorbing the garlic essential oil precursor by using an inorganic porous adsorption material;

preparing garlic essential oil: distilling and dehydrating the inorganic porous adsorbing material adsorbing the garlic essential oil precursor by adopting a steam distillation method to obtain the garlic essential oil.

2. The method for preparing garlic essential oil according to claim 1, further comprising, after the step of converting the fresh garlic juice, before the step of preparing the precursor of garlic essential oil: detecting the allicin content by an HPLC method, wherein the chromatographic conditions are as follows:

a chromatographic column: c18 column, 4.6 m.times.150 mm, 5 μm;

detection wavelength: 254-260 nm;

mobile phase: a mixed solution of methanol and 1% formic acid water with the volume ratio of 60: 40;

flow rate: 0.5-0.8 mL/min;

column temperature: 25-35 ℃;

sample introduction amount: 20 μ L.

3. The method for preparing garlic essential oil according to claim 1, wherein in the step of preparing fresh garlic juice, the fresh garlic is peeled, cleaned, and then pulped in a solvent to 60-200 meshes, the weight ratio of the solvent to the fresh garlic is 3-5:1, and the solvent is water or phosphate buffer solution with pH of 6.0-7.5.

4. The method for preparing garlic essential oil according to claim 1, wherein in the step of preparing fresh garlic juice, the enzymes selected by the enzymolysis method are pectinase and cellulase, the addition amounts of the pectinase and the cellulase are respectively 0.01-0.5% of the weight of the fresh garlic, and the enzymolysis method is performed under the condition of stirring for 0.5-2.0h at 25-50 ℃.

5. The method for preparing garlic essential oil according to claim 1, wherein in the step of converting fresh garlic juice, the exogenous alliin is solid or liquid, has a purity of 5-95%, and has a weight ratio of exogenous alliin to fresh garlic of 0.05-0.5: 1.

6. The method for preparing garlic essential oil according to claim 1, wherein in the step of preparing the garlic essential oil precursor, the polymeric adsorbent material is styrene resin, and the weight ratio of the polymeric adsorbent material to the fresh garlic is 0.2-0.8 times.

7. The method for preparing garlic essential oil according to claim 6, wherein in the garlic essential oil precursor preparation step, the elution reagent is a methanol or ethanol aqueous solution with a mass concentration of 20-95%, the elution volume is 1-5 column volumes, the elution speed is 1-5 column volumes/h, and the device used for recovery is a rotary evaporator.

8. The method for preparing garlic essential oil according to claim 1, wherein in the garlic essential oil precursor adsorption step, the inorganic porous adsorption material is porous alumina, activated carbon or diatomaceous earth, and the weight ratio of the inorganic porous adsorption material to the garlic essential oil precursor is 0.5-2.0: 1.

9. The method for preparing garlic essential oil as claimed in claim 1, wherein in the garlic essential oil preparation step, the weight ratio of purified water used for distillation to the inorganic porous adsorption material is 2-10:1, the distillation time is 1-3h, and the reagent used for dehydration treatment is anhydrous sodium sulfate.

10. The method for preparing garlic essential oil according to claim 1, further comprising, after the garlic essential oil preparing step: the HPLC method is used for measuring the content of the garlic essential oil, and the chromatographic conditions are as follows:

a chromatographic column: c18 column, 4.6 m.times.150 mm, 5 μm;

detection wavelength: 245-260 nm;

mobile phase: a mixed solution of methanol and 1% formic acid water in a volume ratio of 80: 20;

flow rate: 0.5-0.8 mL/min;

column temperature: 25-35 ℃;

sample introduction amount: 20 μ L.

Technical Field

The invention belongs to the field of essential oil preparation, and particularly relates to a preparation method of garlic essential oil.

Background

The garlic essential oil is volatile oil obtained by catalytic cracking of alliin in garlic into allicin through alliinase and deep decomposition and conversion, is rich in various organic sulfur compounds, and has various biological effects of regulating blood fat, reducing cholesterol, preventing cardiovascular diseases, resisting bacteria, viruses and oxidation, enhancing the immunity of organisms and the like.

At present, the garlic essential oil is mostly distilled by water vapor and extracted by a solvent, but the extraction method only can prepare the garlic essential oil due to process limitation, but a large amount of carbohydrate, protein, amino acid and the like in the garlic cannot be recycled, and in the production process, a large amount of waste water with strong garlic flavor is generated by condensation, so that the environmental pollution is easily caused. For example, patent application CN109868181A proposes a method for separating and purifying garlic oil, which adopts a solvent extraction method, but this method is prone to cause organic solvent residue due to the use of a large amount of organic solvent, thereby causing many potential safety hazards, and patent application CN103289810B proposes a method for separating and extracting garlic oil, which adopts a steam distillation method to prepare garlic essential oil, and these production techniques have large distillation treatment capacity, high energy consumption, large wastewater discharge amount, and low garlic essential oil yield, so how to develop a preparation process of garlic essential oil with low energy consumption and production cost, high safety factor, and high garlic essential oil yield is an important approach for solving the above problems.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides the preparation method of the garlic essential oil, which has the advantages of low energy consumption, low production cost, high safety coefficient and high garlic essential oil yield.

In order to achieve the purpose, the invention adopts the technical scheme that:

a preparation method of garlic essential oil comprises the following steps:

preparing fresh garlic juice: peeling and cleaning fresh garlic, pulping in a solvent, performing enzymolysis by adopting an enzymolysis method, and filtering to obtain fresh garlic juice;

conversion of fresh garlic juice: adding exogenous alliin into the fresh garlic juice, and performing conversion treatment on the fresh garlic juice to obtain fresh garlic juice rich in allicin;

preparing a garlic essential oil precursor: adsorbing the fresh garlic juice rich in allicin by using a macromolecular adsorbing material, eluting and recovering the adsorbed macromolecular adsorbing material to obtain a garlic essential oil precursor;

adsorption of garlic essential oil precursor: adsorbing the garlic essential oil precursor by using an inorganic porous adsorption material;

preparing garlic essential oil: distilling and dehydrating the inorganic porous adsorbing material adsorbing the garlic essential oil precursor by adopting a steam distillation method to obtain the garlic essential oil.

Preferably, after the step of converting the fresh garlic juice, the step of preparing the precursor of garlic essential oil further comprises: detecting the allicin content by an HPLC method, wherein the chromatographic conditions are as follows:

a chromatographic column: c18 column, 4.6 m.times.150 mm, 5 μm;

detection wavelength: 254-260 nm;

mobile phase: a mixed solution of methanol and 1% formic acid water with the volume ratio of 60: 40;

flow rate: 0.5-0.8 mL/min;

column temperature: 25-35 ℃;

sample introduction amount: 20 μ L.

Preferably, in the fresh garlic juice preparation step, the fresh garlic is peeled, cleaned and then pulped in a solvent to 60-200 meshes, the weight ratio of the solvent to the fresh garlic is 3-5:1, and the solvent is water or phosphate buffer solution with the pH value of 6.0-7.5.

Preferably, in the step of preparing the fresh garlic juice, the enzymes selected by the enzymolysis method are pectinase and cellulase, the addition amounts of the pectinase and the cellulase are respectively 0.01-0.5% of the weight of the fresh garlic, and the enzymolysis condition of the enzymolysis method is that the mixture is stirred for 0.5-2.0h at the temperature of 25-50 ℃.

Preferably, in the step of transforming the fresh garlic juice, the exogenous alliin is solid or liquid, the purity is 5-95%, and the weight ratio of the exogenous alliin to the fresh garlic is 0.05-0.5: 1.

Preferably, in the step of preparing the garlic essential oil precursor, the polymer adsorbing material is styrene resin, and the weight ratio of the polymer adsorbing material to the fresh garlic is 0.2-0.8 times.

Preferably, in the preparation step of the garlic essential oil precursor, the elution reagent is a methanol or ethanol aqueous solution with the mass concentration of 20-95%, the elution volume is 1-5 column volumes, the elution speed is 1-5 column volumes/h, and the device used for recovery is a rotary evaporator.

Preferably, in the adsorption step of the garlic essential oil precursor, the inorganic porous adsorption material is porous alumina, activated carbon or diatomite, and the weight ratio of the inorganic porous adsorption material to the garlic essential oil precursor is 0.5-2.0: 1.

Preferably, in the preparation step of the garlic essential oil, the weight ratio of purified water used for distillation to the inorganic porous adsorption material is 2-10:1, the distillation time is 1-3h, and the reagent used for dehydration treatment is anhydrous sodium sulfate.

Preferably, the method further comprises the following steps after the preparation step of the garlic essential oil: the HPLC method is used for measuring the content of the garlic essential oil, and the chromatographic conditions are as follows:

a chromatographic column: c18 column, 4.6 m.times.150 mm, 5 μm;

detection wavelength: 245-260 nm;

mobile phase: a mixed solution of methanol and 1% formic acid water in a volume ratio of 80: 20;

flow rate: 0.5-0.8 mL/min;

column temperature: 25-35 ℃;

sample introduction amount: 20 μ L.

Compared with the prior art, the invention has the advantages and positive effects that:

1. the invention provides a preparation method of garlic essential oil, which organically combines an enzymolysis method, a source alliin conversion method, a macromolecular adsorption material adsorption method, a distillation method and the like, and can reduce energy consumption and cost, reduce pollution and improve the yield of the garlic essential oil;

2. the invention provides a preparation method of garlic essential oil, which selectively adsorbs allicin serving as a garlic oil precursor from garlic juice, and obtains an allicin concentrated solution after elution treatment, so that the distillation amount can be greatly reduced, garlic polysaccharide and amino acid in unadsorbed solution can be further extracted and purified, corresponding garlic products are obtained, and the comprehensive utilization efficiency of garlic is improved;

3. the invention provides a preparation method of garlic essential oil, which adopts an inorganic porous adsorption material to adsorb garlicin from garlicin eluent, not only can further concentrate the precursor substance of the garlic oil and effectively reduce the evaporation amount, but also adopts the inorganic porous material during distillation, the material permeability is good, the distillation process is stable and controllable, and the content of the main active substance diallyl trisulfide in the obtained garlic oil is improved by about 40-45 percent from 30-35 percent of the content of the main active substance diallyl trisulfide in the traditional method.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The embodiment of the invention provides a preparation method of garlic essential oil, which comprises the following steps:

s1, preparing fresh garlic juice: peeling and cleaning fresh garlic, pulping in a solvent, performing enzymolysis by adopting an enzymolysis method, and filtering to obtain fresh garlic juice;

in the preparation step of the fresh garlic juice, the fresh garlic is peeled, cleaned and then pulped in a solvent to obtain the garlic pulp of 60-200 meshes.

S2, conversion of fresh garlic juice: adding exogenous alliin into the fresh garlic juice, and performing conversion treatment on the fresh garlic juice to obtain fresh garlic juice rich in allicin;

in the above step of converting fresh garlic juice, the reason why exogenous alliin is added to fresh garlic juice is that: because the garlic raw material contains less garlicin, the garlic essential oil production rate is low, about 0.25-0.35%, in order to raise the garlic essential oil yield, the invention adds exogenous alliin, and the alliinase converts the allicin into garlic essential oil, and then converts the garlic essential oil into garlic essential oil, and can effectively increase the garlic essential oil production rate to 2-2.5%.

S3, preparing a garlic essential oil precursor: adsorbing the fresh garlic juice rich in allicin by using a macromolecular adsorbing material, eluting and recovering the adsorbed macromolecular adsorbing material to obtain a garlic essential oil precursor;

in the step S3, the polymer adsorbent selected by the present invention is styrene resin, which has the advantages of large sample loading capacity and low requirements for equipment and operation, while the existing garlicin purification technology mostly adopts C18 reverse phase silica gel, which has high material cost, large dosage and high requirements for equipment and operation steps.

S4, adsorbing the garlic essential oil precursor: adsorbing the garlic essential oil precursor by using an inorganic porous adsorption material;

in the above steps S4 and S5, the reason why the present invention selects the use of the polymeric adsorbent in combination with the inorganic adsorbent is that: firstly, distillation is needed when preparing garlic oil, the distillation amount of the traditional technology is about 3-5 times of that of raw materials, the evaporation amount is large, the energy consumption is high, the sewage discharge amount is large, and garlic oil precursor substances, namely allicin, can be selectively and efficiently adsorbed from garlic juice by using a macromolecular adsorbing material and an inorganic adsorbing material in a combined way; the distillation amount can be greatly reduced, and the distillation amount is about 4 to 5.5 percent of the raw material; and thirdly, garlic polysaccharide and amino acid in the garlic juice can be further extracted and purified to obtain corresponding garlic products, so that the comprehensive utilization rate of the garlic can be improved.

S5, preparing garlic essential oil: distilling and dehydrating the inorganic porous adsorbing material adsorbing the garlic essential oil precursor by adopting a steam distillation method to obtain the garlic essential oil.

In a preferred embodiment, after the step of converting the fresh garlic juice, the step of preparing the precursor of garlic essential oil further comprises: detecting the allicin content by an HPLC method, wherein the chromatographic conditions are as follows:

a chromatographic column: c18 column, 4.6 m.times.150 mm, 5 μm;

detection wavelength: 254-260 nm;

mobile phase: a mixed solution of methanol and 1% formic acid water with the volume ratio of 60: 40;

flow rate: 0.5-0.8 mL/min;

column temperature: 25-35 ℃;

sample introduction amount: 20 μ L.

In a preferred embodiment, in the step of preparing the fresh garlic juice, the fresh garlic is peeled, cleaned and then pulped in a solvent to 60-200 meshes, the weight ratio of the solvent to the fresh garlic is 3-5:1, and the solvent is water or phosphate buffer solution with the pH value of 6.0-7.5.

In the above preferred embodiment, the weight ratio of the solvent to the fresh garlic can be selected from 3:1, 4:1, 5:1 or any value within the above range according to actual needs, and the weight ratio falls within the protection scope of the present invention.

In a preferred embodiment, in the step of preparing the fresh garlic juice, the enzymes selected by the enzymolysis method are pectinase and cellulase, the addition amounts of the pectinase and the cellulase are respectively 0.01-0.5% of the weight of the fresh garlic, and the enzymolysis condition of the enzymolysis method is that the mixture is stirred for 0.5-2.0h at the temperature of 25-50 ℃.

In the above preferred embodiment, the addition amount of the pectinase and cellulase is selected from 0.01, 0.1, 0.2, 0.3, 0.4, 0.5% of the weight of the fresh garlic or any value selected from the above ranges according to actual needs and falling within the protection range of the present invention, the enzymolysis temperature is selected from 25, 30, 35, 40, 45, 50 ℃ or any value selected from the above ranges according to actual needs and falling within the protection range of the present invention, and the stirring time is selected from 0.5, 1.0, 1.5, 2.0 hours or any value selected from the above ranges according to actual needs and falling within the protection range of the present invention.

In a preferred embodiment, in the step of transforming fresh garlic juice, the exogenous alliin is solid or liquid, the purity is 5-95%, and the weight ratio of the exogenous alliin to the fresh garlic is 0.05-0.5: 1.

In the above preferred embodiment, the purity of the exogenous alliin can be selected from 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 95% or any value within the above range according to actual needs, and the exogenous alliin falls within the protection scope of the present invention.

In a preferred embodiment, in the step of preparing the garlic essential oil precursor, the polymeric adsorbent material is styrene resin, and the weight ratio of the polymeric adsorbent material to the fresh garlic is 0.2-0.8 times.

In a preferred embodiment, the styrene resin is selected from any one of D101, AB-8 and HPD-100.

In a preferred embodiment, in the step of preparing the garlic essential oil precursor, the elution reagent is a methanol or ethanol aqueous solution with a mass concentration of 20-95%, the elution volume is 1-5 column volumes, the elution speed is 1-5 column volumes/h, and the device used for recovery is a rotary evaporator.

In a preferred embodiment, in the adsorption step of the garlic essential oil precursor, the inorganic porous adsorption material is porous alumina, activated carbon or diatomite, and the weight ratio of the inorganic porous adsorption material to the garlic essential oil precursor is 0.5-2.0: 1.

In a preferred embodiment, in the preparation step of the garlic essential oil, the weight ratio of purified water used for distillation to the inorganic porous adsorption material is 2-10:1, the distillation time is 1-3h, and the reagent used for dehydration treatment is anhydrous sodium sulfate.

In a preferred embodiment, the method further comprises the following steps after the garlic essential oil preparation step: the HPLC method is used for measuring the content of the garlic essential oil, and the chromatographic conditions are as follows:

a chromatographic column: c18 column, 4.6 m.times.150 mm, 5 μm;

detection wavelength: 245-260 nm;

mobile phase: a mixed solution of methanol and 1% formic acid water in a volume ratio of 80: 20;

flow rate: 0.5-0.8 mL/min;

column temperature: 25-35 ℃;

sample introduction amount: 20 μ L.

In order to more clearly and specifically describe the preparation method of the garlic essential oil provided by the embodiments of the present invention, the following description will be made with reference to specific embodiments.

Comparative example 1

The comparative example provides an extraction method of garlic essential oil, which comprises the following specific steps:

(1) peeling and cleaning fresh garlic, adding water with the weight 3 times of that of the fresh garlic, pulping to 80 meshes, respectively adding pectinase and cellulase with the weight 0.1% of that of the fresh garlic, stirring and extracting at 55 ℃ for 1h, and filtering to obtain fresh garlic juice;

(2) adding exogenous alliin powder with the purity of 10% into the fresh garlic juice, wherein the addition amount is 0.6 times of the weight of the fresh garlic, fully reacting at 40 ℃, and performing conversion treatment to obtain the fresh garlic juice rich in allicin;

(3) adsorbing allicin from fresh garlic juice rich in allicin by using HPD-100 type high molecular adsorption resin with the weight of 0.3 time of that of fresh garlic, enabling the garlic juice to pass through a resin column at the flow rate of 3 column volumes/h, enabling an eluent to be 15% ethanol water solution, eluting for 2 column volumes at the elution speed of 2 column volumes/h, and recovering an elution solvent by using a rotary evaporator to prepare a garlic essential oil precursor;

(4) adsorbing the garlic essential oil precursor by using activated carbon with the weight 1 time that of the garlic essential oil precursor, and adsorbing for 2 hours at 25 ℃;

(5) adding purified water 5 times the weight of the activated carbon, distilling the porous alumina adsorbing the precursor of the garlic essential oil by using a steam distillation method for 0.5h, and adding anhydrous sodium sulfate into the distilled garlic essential oil for dehydration to obtain the garlic essential oil;

(6) and (3) detecting the purity and concentration of the diallyl trisulfide in the prepared garlic essential oil by using an HPLC method.

Comparative example 2

The comparative example provides an extraction method of garlic essential oil, which comprises the following specific steps:

(1) peeling and cleaning fresh garlic, adding water with the weight 3 times of that of the fresh garlic, pulping to 80 meshes, respectively adding pectinase and cellulase with the weight 0.1% of that of the fresh garlic, stirring and extracting at 15 ℃ for 1h, and filtering to obtain fresh garlic juice;

(2) adding exogenous alliin powder with the purity of 10% into fresh garlic juice, wherein the addition amount is 0.2 times of the weight of garlic rice, fully reacting at 35 ℃, and performing conversion treatment to obtain fresh garlic juice rich in allicin;

(3) adsorbing garlicin from fresh garlic juice rich in garlicin by using HPD-100 type high molecular adsorption resin with weight of 0.2 times of fresh garlic, wherein flow rate of garlic juice passing through resin column is 15 column volumes/h. Eluting with 35% ethanol water solution at 5 column volume and 3 column volume/h, and recovering the eluting solvent with rotary evaporator to obtain garlic essential oil precursor;

(4) adsorbing the garlic essential oil precursor by using activated carbon with the weight 1 time that of the garlic essential oil precursor, and adsorbing for 2 hours at 25 ℃;

(5) adding purified water with the weight 1 time that of the activated carbon, distilling the porous alumina adsorbing the precursor of the garlic essential oil by using a steam distillation method, wherein the distillation time is 3.5h, and adding anhydrous sodium sulfate into the distilled garlic essential oil for dehydration to prepare the garlic essential oil;

(6) and (3) detecting the purity and concentration of the diallyl trisulfide in the prepared garlic essential oil by using an HPLC method.

Comparative example 3

The comparative example provides a traditional preparation method of garlic essential oil, which specifically comprises the following steps:

(1) pretreatment: placing fresh garlic cloves in 6 times of drinking water, soaking for 2h, washing with running water to remove garlic skin soil, draining clear water, and placing on a crusher to crush into garlic pulp with the granularity of about 150 meshes;

(2) performing alliinase hydrolysis: adding alliinase activity regulator (blue vitriol 30-50g, strong ammonia water 0.3kg, halogen salt more than 20 g) into per ton of garlic pulp, and performing enzymolysis at room temperature for more than 1h to completely convert alliin into allicin;

(3) charging and distilling: uniformly loading the garlic subjected to enzymolysis into a steamer, uniformly treating to avoid steam short circuit, sealing the steamer, and boiling with strong fire, wherein the steam generation amount is controlled to be 20-40 kg/h. Steaming until the garlic residue has no garlic essential oil smell;

(4) and (3) essential oil separation: placing the distilled garlic essential oil and water into an oil-water separator for standing, and separating out an oil phase which is a garlic essential oil crude product;

(5) and (3) refining garlic essential oil: slowly passing the garlic oil through a drying silica gel column to remove residual water, thus obtaining the refined garlic essential oil.

Example 1

The embodiment provides an extraction method of garlic essential oil, which comprises the following specific steps:

(1) peeling and cleaning fresh garlic, adding water with the weight 5 times of that of the fresh garlic, pulping to 200 meshes, respectively adding pectinase and cellulase with the weight 0.5 percent of the weight of the fresh garlic, stirring and extracting at 40 ℃ for 1.5 hours, and filtering to obtain fresh garlic juice for later use;

(2) adding exogenous alliin powder with purity of 40% into fresh garlic juice, adding 0.05 times of fresh garlic weight, reacting at 40 deg.C, and converting to obtain fresh garlic juice rich in allicin;

(3) adsorbing garlicin from fresh garlic juice rich in garlicin by using D101 type polymeric adsorbent resin with the weight of 0.5 time of that of fresh garlic, enabling the garlic juice to pass through a resin column at the flow rate of 8 column volumes/h, enabling an eluent to be 95% ethanol water solution, eluting for 5 column volumes at the elution speed of 5 column volumes/h, and recovering an elution solvent by using a rotary evaporator to prepare a garlic essential oil precursor;

(4) adsorbing the precursor of the garlic essential oil by using porous alumina with the weight 2 times that of the precursor of the garlic essential oil, and adsorbing for 4 hours at 25 ℃.

(5) Adding purified water 10 times the weight of porous alumina, distilling porous alumina adsorbing the precursor of garlic essential oil by steam distillation for 3h, and adding anhydrous sodium sulfate into distilled garlic essential oil for dehydration to obtain garlic essential oil.

(6) And (3) detecting the purity and concentration of the diallyl trisulfide in the prepared garlic essential oil by using an HPLC method.

Example 2

The embodiment provides an extraction method of garlic essential oil, which comprises the following specific steps:

(1) peeling and cleaning fresh garlic, adding water 4 times the weight of the fresh garlic, pulping to 100 meshes, respectively adding pectinase and cellulase 0.2% of the weight of the fresh garlic, stirring and extracting at 40 ℃ for 1h, and filtering to obtain fresh garlic juice;

(2) adding exogenous alliin powder with the purity of 20% into the fresh garlic juice, wherein the addition amount of the exogenous alliin powder is 0.1 time of the weight of the garlic cloves; fully reacting at 35 ℃, and performing conversion treatment to obtain the fresh garlic juice rich in allicin.

(3) Adsorbing garlicin from fresh garlic juice rich in garlicin by AB-8 type polymeric adsorbent resin with weight of 0.3 times of fresh garlic, wherein flow rate of garlic juice passing through resin column is 5 column volume/h. Eluting with 70% ethanol water solution at 3 column volumes/h, and recovering the eluting solvent with rotary evaporator to obtain Bulbus Allii essential oil precursor;

(4) adsorbing the garlic essential oil precursor by using porous alumina with the weight 1.5 times of that of the garlic essential oil precursor, and adsorbing for 4 hours at 25 ℃;

(5) adding purified water 8 times the weight of the porous alumina, distilling the porous alumina adsorbing the precursor of the garlic essential oil by using a steam distillation method for 2 hours, and adding anhydrous sodium sulfate into the distilled garlic essential oil for dehydration to obtain the garlic essential oil.

(6) And (3) detecting the purity and concentration of the diallyl trisulfide in the prepared garlic essential oil by using an HPLC method.

Example 3

The embodiment provides an extraction method of garlic essential oil, which comprises the following specific steps:

(1) peeling and cleaning fresh garlic, adding water with the weight 3 times of that of the fresh garlic, pulping to 80 meshes, respectively adding pectinase and cellulase with the weight 0.1% of that of the fresh garlic, stirring and extracting at 35 ℃ for 1h, and filtering to obtain fresh garlic juice for later use;

(2) adding exogenous alliin powder with the purity of 10% into the fresh garlic juice, wherein the addition amount of the exogenous alliin powder is 0.2 time of the weight of the garlic cloves; reacting at 35 deg.C, and converting to obtain fresh garlic juice rich in allicin;

(3) adsorbing garlicin from fresh garlic juice rich in garlicin by using HPD-100 type high molecular adsorption resin with weight of 0.3 times of garlic cloves, wherein flow rate of garlic juice passing through resin column is 3 column volumes/h. Eluting with 50% ethanol water solution at 2 column volume and 2 column volume/h, and recovering the eluting solvent with rotary evaporator to obtain Bulbus Allii essential oil precursor;

(4) adsorbing the garlic essential oil precursor by using activated carbon with the weight 1 time that of the garlic essential oil precursor, and adsorbing for 4 hours at 25 ℃;

(5) adding purified water 5 times the weight of the activated carbon, distilling the porous alumina adsorbing the precursor of the garlic essential oil by using a steam distillation method for 1.5h, and adding anhydrous sodium sulfate into the distilled garlic essential oil for dehydration to obtain the garlic essential oil;

(6) and (3) detecting the purity and concentration of the diallyl trisulfide in the prepared garlic essential oil by using an HPLC method.

Performance testing

The garlic essential oil prepared in each of the above examples and comparative examples was subjected to measurement and calculation of evaporation amount, purity of diallyl trisulfide and yield of garlic essential oil, and the calculation results were as follows:

table 1 test results of garlic essential oil prepared in examples and comparative examples

Test items	Amount of evaporation	Purity of diallyl trisulfide	Garlic oil yield
				Comparative example 1	50 percent of the weight of the fresh garlic	18.6％	0.01％
Comparative example 2	15 percent of the weight of the fresh garlic	25.8％	0.83％
				Comparative example 3	150 percent of the weight of the fresh garlic	29.7％	0.43％
Example 1	5.2 percent of the weight of the fresh garlic	48.62％	2.23％
				Example 2	4.6 percent of the weight of the fresh garlic	46.59％	2.51％
Example 3	4.1 percent of the weight of the fresh garlic	47.73％	2.35％

As can be seen from the above table, the preparation methods provided in examples 1 to 3 are superior to the extraction process described in the comparative example in terms of evaporation amount, diallyl trisulfide purity, and garlic essential oil yield, and the yield of the finally prepared garlic essential oil is as high as 2.51%, so that the preparation process provided by the present invention can not only effectively reduce the evaporation amount, but also produce garlic essential oil with high purity and high yield, and therefore, the preparation method provided by the present invention has a very broad application prospect in the field of garlic essential oil preparation.