阅读说明：本技术 一种提取枸杞中玉米黄素的方法和应用 (Method for extracting zeaxanthin from Chinese wolfberry and application ) 是由 李春美 沈齐若男 朱婷 于 2021-06-03 设计创作，主要内容包括：本发明提供了一种提取枸杞中玉米黄素的方法和应用,该提取方法包括,将枸杞粉加入到含离子液体和无机碱的乙醇溶液中,超声提取,一次离心分离后取上清液,随后旋蒸去除乙醇,加入去离子水混匀后在2-7℃下二次离心分离,取沉淀即得。本发明所提供的提取枸杞中玉米黄素的方法采用素有绿色溶剂之称的离子液体与碱和乙醇组成的混合溶剂代替传统提取剂,辅以超声技术,将提取和皂化同时进行,提取彻底且提取效率高,所使用的乙醇溶剂可回收后循环再利用,提取过程对环境影响很小,具有良好的实际应用价值。(The invention provides a method for extracting zeaxanthin from Chinese wolfberry and application thereof, wherein the extraction method comprises the steps of adding Chinese wolfberry powder into an ethanol solution containing ionic liquid and inorganic base, carrying out ultrasonic extraction, taking supernatant after primary centrifugal separation, then carrying out rotary evaporation to remove ethanol, adding deionized water, mixing uniformly, carrying out secondary centrifugal separation at 2-7 ℃, and taking precipitate to obtain the zeaxanthin. The method for extracting the zeaxanthin from the medlar provided by the invention adopts the mixed solvent composed of the ionic liquid called green solvent, alkali and ethanol to replace the traditional extractant, and is assisted by the ultrasonic technology, so that the extraction and the saponification are carried out simultaneously, the extraction is thorough, the extraction efficiency is high, the used ethanol solvent can be recycled after being recovered, the influence of the extraction process on the environment is small, and the method has good practical application value.)

1. A method for extracting zeaxanthin from Chinese wolfberry is characterized in that,

the method comprises the following steps: adding fructus Lycii powder into ethanol solution containing ionic liquid and inorganic base, ultrasonic extracting, centrifuging for the first time, collecting supernatant, removing ethanol by rotary evaporation, adding deionized water, mixing, centrifuging at 2-7 deg.C for the second time, and collecting precipitate.

2. The method for extracting zeaxanthin from Lycium barbarum according to claim 1,

the ionic liquid is one or more of [ Bmim ] BF4, [ Bmim ] Cl, [ Emim ] OAC, [ Bmim ] OAC and [ Hmim ] OAC, preferably [ Hmim ] OAC;

and/or, the inorganic base is NaOH and/or KOH, preferably KOH.

3. The method for extracting zeaxanthin from Lycium barbarum according to claim 1 or 2,

in the ethanol solution, the ethanol solution is added,

the content of the ionic liquid is 0.075-0.12g/ml, and preferably 0.1 g/ml;

and/or the concentration of the inorganic base is 4 to 8 wt%, preferably 6 wt%.

4. The method for extracting zeaxanthin from Lycium barbarum of claim 3,

the ratio of the added amount of the medlar powder to the added amount of the ethanol solution is controlled to be 1: 35-42.

5. The method for extracting zeaxanthin from Lycium barbarum according to any one of claims 1-4,

the ultrasonic time of the ultrasonic extraction is 35-42min, preferably 40 min;

and/or the temperature of the ultrasonic extraction is 25-50 ℃, preferably 40 ℃;

and/or the ultrasonic power of the ultrasonic extraction is 400-445W, preferably 420W.

6. The method for extracting zeaxanthin from Lycium barbarum according to claim 1,

adding an acetic acid aqueous solution until the mixed solution is adjusted to be neutral before the primary centrifugal separation;

preferably, the concentration of the acetic acid aqueous solution is 20 wt%.

7. The method for extracting zeaxanthin from Lycium barbarum according to any one of claims 1-6,

the mass of the deionized water added is 9-12 times, preferably 10 times of the mass of the ionic liquid.

8. The method for extracting zeaxanthin from Lycium barbarum according to any one of claims 1-6,

the number of times of adding deionized water, uniformly mixing and carrying out secondary centrifugal separation is multiple times, and 2-3 times is preferred.

9. The method for extracting zeaxanthin from Lycium barbarum according to claim 1,

the temperature, the rotating speed and the time of the secondary centrifugal separation are respectively 4 ℃, 8000-12000rpm and 15-22 min.

10. Use of a method according to any one of claims 1 to 9 for the extraction of zeaxanthin from lycium barbarum.

Technical Field

The invention relates to the technical field of extraction of active ingredients of traditional Chinese medicines, and particularly relates to a method for extracting zeaxanthin from Chinese wolfberry and application of the zeaxanthin.

Background

The medlar is rich in nutrition, which is clearly recorded in compendium of materia Medica: the Ningxia Zhongning wolfberry fruit is the superior and famous medicinal material and has excellent eye protecting and eye disease treating effect; the existing research proves that the functional component in the medlar for eye health care is mainly carotenoid mainly containing zeaxanthin, and has various physiological functions of preventing cataract, age-related macular degeneration, cancer, cardiovascular diseases and the like.

In mature medlar, the carotenoid is relatively single in composition and mostly exists in an esterified form, most of the carotenoid is zeaxanthin dipalmitate, and a large amount of free zeaxanthin and a small amount of other carotenoids can be obtained by saponification and hydrolysis, so the method is one of ideal raw materials for extracting zeaxanthin.

In the prior art, the extraction method of the Chinese wolfberry zeaxanthin comprises the following steps: firstly, extracting zeaxanthin esters in the medlar by using an organic solvent, and then adding alkali liquor to saponify the zeaxanthin esters; the method has the advantages of complex steps, long time consumption, more organic solvents, easy environmental pollution, certain toxicity and no compliance with green chemistry concepts.

In conclusion, research and development of a high-efficiency and environment-friendly method for extracting zeaxanthin from lycium barbarum is a key technical problem to be solved urgently in the field.

Disclosure of Invention

The invention aims to provide a method for extracting zeaxanthin from Chinese wolfberry and application thereof.

The invention adopts the following technical scheme:

the invention provides a method for extracting zeaxanthin from Chinese wolfberry, which comprises the following steps:

adding fructus Lycii powder into ethanol solution containing ionic liquid and inorganic base, ultrasonic extracting, centrifuging for the first time, collecting supernatant, removing ethanol by rotary evaporation, adding deionized water, mixing, centrifuging at 2-7 deg.C for the second time, and collecting precipitate.

In the technical scheme, the ionic liquid is one or more of [ Bmim ] BF4, [ Bmim ] Cl, [ Emim ] OAC, [ Bmim ] OAC and [ Hmim ] OAC.

In particular, in a preferred embodiment of the invention, the ionic liquid is [ Hmim ] OAC.

In the above technical scheme, the inorganic base is NaOH and/or KOH.

In particular, in a preferred embodiment of the present invention, the inorganic base is KOH.

Further, in the above technical scheme, the content of the ionic liquid in the ethanol solution is 0.075-0.12 g/ml.

Specifically, in a preferred embodiment of the present invention, the content of the ionic liquid in the ethanol solution is 0.1 g/ml.

Further, in the above technical solution, the concentration of the inorganic base in the ethanol solution is 4 to 8 wt%.

Specifically, in a preferred embodiment of the present invention, the concentration of the inorganic base in the ethanol solution is 6 wt%.

In detail, in the above technical scheme, the ratio of the added amounts of the medlar powder and the ethanol solution is controlled to be 1: 35-42.

Still further, in the above technical solution, the ultrasound time of the ultrasound extraction is 35-42min, preferably 40 min.

Still further, in the above technical scheme, the temperature of the ultrasonic extraction is 25-50 ℃, preferably 40 ℃;

still further, in the above technical solution, the ultrasonic power of the ultrasonic extraction is 400-.

In the technical scheme, the method for extracting the zeaxanthin from the medlar further comprises the step of adding an acetic acid aqueous solution until the mixed solution is adjusted to be neutral before the primary centrifugal separation.

Preferably, in one embodiment of the present invention, the concentration of the aqueous acetic acid solution is 20 wt%.

Still further, in the above technical solution, the mass of the deionized water added is 9 to 12 times, preferably 10 times of the mass of the ionic liquid.

Still further, in the above technical solution, the number of times of adding deionized water, mixing uniformly, and performing secondary centrifugal separation is multiple times, preferably 2 to 3 times.

In the technical scheme, the temperature, the rotating speed and the time of the secondary centrifugal separation are respectively 4 ℃, 8000-DEG F12000 rpm and 15-22 min.

The invention also provides application of the method in extraction of the lycium ruthenicum zeaxanthin.

Compared with the prior art, the invention has the beneficial effects that:

the method for extracting the zeaxanthin from the medlar provided by the invention adopts the mixed solvent composed of the ionic liquid called green solvent, alkali and ethanol to replace the traditional extractant, and is assisted by the ultrasonic technology, so that the extraction and the saponification are carried out simultaneously, the extraction is thorough, the extraction efficiency is high, the used ethanol solvent can be recycled after being recovered, the influence of the extraction process on the environment is small, and the method has good practical application value.

Drawings

FIG. 1 is a graph comparing the results of different ionic liquids on the content of zeaxanthin in extracted Lycium barbarum in example 1 of the present invention;

FIG. 2 is a high performance liquid chromatogram of a sample obtained by extracting zeaxanthin from Lycium barbarum using [ Hmim ] OAC as an ionic liquid in example 1 of the present invention;

FIG. 3 is a graph comparing the results of KOH concentrations versus zeaxanthin content in extracted Lycium barbarum in example 2 of the present invention;

FIG. 4 is a graph comparing the results of different concentrations of ionic liquid on the content of zeaxanthin in extracted Lycium barbarum in example 3 of the present invention;

FIG. 5 is a graph comparing the results of different ultrasound times on the content of zeaxanthin in extracted Lycium barbarum in example 4 of the present invention;

FIG. 6 is a comparison graph of the results of comparing the content of zeaxanthin in extracted Lycium barbarum with different feed liquids in example 5 of the present invention;

FIG. 7 is a graph comparing the results of different ultrasonic powers on the content of zeaxanthin in extracted Lycium barbarum in example 6 of the present invention;

FIG. 8 is a high performance liquid chromatogram of a sample obtained by extracting zeaxanthin from Lycium barbarum of the present invention in comparative example 1;

FIG. 9 is a high performance liquid chromatogram of a sample obtained by extracting zeaxanthin from Lycium barbarum in comparative example 2 according to the present invention;

FIG. 10 is a high performance liquid chromatogram of a sample obtained by extracting zeaxanthin from Lycium barbarum using a conventional organic solvent in comparative example 3 according to the present invention.

Detailed Description

The present invention is further described in detail below with reference to specific examples so that those skilled in the art can more clearly understand the present invention.

The following examples are given for the purpose of illustration only and are not intended to limit the scope of the invention. All other embodiments obtained by a person skilled in the art based on the specific embodiments of the present invention without any inventive step are within the scope of the present invention.

In the examples of the present invention, unless otherwise specified, all technical means used are conventional means well known to those skilled in the art. In the examples of the present invention, the raw materials used were all commercially available products.

Example 1

This example contrasts the influence of different ionic liquids to extracting zeaxanthin in the matrimony vine, and the specific process is as follows:

weighing 0.2g of freeze-dried medlar powder, and respectively adding the freeze-dried medlar powder into ethanol solution containing 0.1g/ml of ionic liquid ([ Bmim ] BF4, [ Bmim ] Cl, [ Emim ] OAC, [ Bmim ] OAC and [ Hmim ] OAC) and 6 wt% of KOH, wherein the material-liquid ratio is controlled to be 1: 30, performing ultrasonic extraction for 40min at 40 ℃ under the condition that the ultrasonic power is 350W, centrifuging for 2min at 10000prm, taking supernatant, performing rotary evaporation to remove ethanol, adding deionized water with the mass being 10 times of that of the ionic liquid as an anti-solvent, destroying the interaction between the ionic liquid and the zeaxanthin, reducing the solubility of the zeaxanthin, performing secondary centrifugal separation for 20min at 4 ℃ and 10000rpm, wherein the supernatant is an aqueous solution containing the ionic liquid, the zeaxanthin is deposited at the bottom of a centrifugal tube, repeatedly adding deionized water as the anti-solvent, performing secondary centrifugal separation for 2-3 times, and mixing precipitates obtained in the secondary centrifugal separation until the formol is dropwise added into the supernatant to avoid precipitation, and analyzing the content of the zeaxanthin extracted under the condition of adopting different ionic liquids by adopting an HPLC method.

Specifically, the conditions and procedures for HPLC analysis were as follows:

YMC-C30 column (4.6 mm. times.250 mm, 5 μm);

mobile phase a phase: methanol-acetonitrile-water (81: 14: 5, v/v/v);

mobile phase B phase: methylene chloride-methyl tert-butyl ether (1: 1, v/v);

flow rate: 1 mL/min;

column temperature: 25 ℃;

detection wavelength: 450 nm.

Elution conditions:

0min, mobile phase B: 16 percent;

22min, mobile phase B: 17 percent;

40min, mobile phase B: 55 percent;

45min, mobile phase B: 16 percent;

55min, mobile phase B: 16 percent.

Drawing a standard curve:

weighing 2mg of zeaxanthin standard substance, fixing the volume to 10mL by using a mobile phase, preparing a standard solution of 200 mug/mL, operating in a dark place, and storing in the dark place at-80 ℃ for later use; the standard solution was diluted to 10. mu.g/mL, 20. mu.g/mL, 50. mu.g/mL, 100. mu.g/mL and 200. mu.g/mL, respectively, and then passed through a 0.45 μm organic filter for use.

Taking the mass concentration as an abscissa and the peak area as an ordinate, performing linear regression to obtain a standard curve as follows:

y＝4.19*10⁷x+22850；

its coefficient of correlation R²＝0.9999。

The results of the effect of different ionic liquids on the extraction of zeaxanthin from lycium barbarum are shown in fig. 1; as can be seen from FIG. 1, the anion structure in the ionic liquid has a significant influence on the extraction yield of zeaxanthin, while the cationic structure has a smaller influence on the extraction yield of zeaxanthin, and the extraction efficiency of zeaxanthin in medlar by different ionic liquids is as follows: [ Hmim ] OAC > [ Emim ] OAC > [ Bmim ] OAC > [ Bmim ] Cl > [ Bmim ] BF 4.

FIG. 2 shows a high performance liquid chromatogram of a sample obtained by extracting zeaxanthin from Lycium barbarum using [ Hmim ] OAC as an ionic liquid in example 1 of the present invention.

Example 2

This example compares the influence of different concentrations of KOH on extracting zeaxanthin from lycium barbarum, and the specific process is as follows:

weighing 0.2g of freeze-dried medlar powder, and respectively adding the freeze-dried medlar powder into ethanol solutions containing 0.1g/ml of [ Hmim ] OAC ionic liquid and KOH with different concentrations (2 wt%, 4 wt%, 6 wt%, 8 wt%, 10 wt% and 12 wt%), wherein the material-liquid ratio is controlled to be 1: 30, performing ultrasonic extraction for 40min at 40 ℃ under the condition that the ultrasonic power is 350W, centrifuging for 2min at 10000prm, taking supernatant, performing rotary evaporation to remove ethanol, adding deionized water with the mass being 10 times of that of the ionic liquid as an anti-solvent, destroying the interaction between the ionic liquid and the zeaxanthin, reducing the solubility of the zeaxanthin, performing secondary centrifugal separation for 20min at 4 ℃ and 10000rpm, wherein the supernatant is an aqueous solution containing the ionic liquid, the zeaxanthin is deposited at the bottom of a centrifugal tube, repeatedly adding deionized water as the anti-solvent, performing secondary centrifugal separation for 2-3 times, and mixing precipitates obtained in the secondary centrifugal separation until the precipitation of the forskolin is not generated in the supernatant, and analyzing the content of the zeaxanthin extracted under the conditions of different concentrations of KOH by adopting the same HPLC method as that in the example 1.

The results of the effect of KOH concentrations on zeaxanthin extraction from lycium barbarum are shown in fig. 3; as can be seen from FIG. 3, as the KOH concentration increases, the zeaxanthin content increases and then decreases; when the concentration of the alkali solution is less than 6 wt%, the saponification is incomplete, the zeaxanthin ester cannot be converted into the zeaxanthin, and the content of the extracted zeaxanthin is low; when the concentration of the alkali solution is 6 wt%, the content of the zeaxanthin reaches the maximum value, the volume fraction of the alkali solution is continuously increased, and the content of the zeaxanthin is reduced, which may be because the zeaxanthin is easily decomposed and unstable in a strong alkali environment, or because the alkali concentration is high, the washing frequency is increased, and the zeaxanthin loss may be caused in the process.

Example 3

This example contrasts the influence of ionic liquid of different concentrations to extracting zeaxanthin in the matrimony vine, and the specific process is as follows:

weighing 0.2g of freeze-dried medlar powder, and respectively adding the freeze-dried medlar powder into ethanol solutions containing [ Hmim ] OAC ionic liquid and 6 wt% KOH with different concentrations (0.03g/ml, 0.05g/ml, 0.08g/ml, 0.10g/ml, 0.12g/ml and 0.15g/ml), wherein the material-liquid ratio is controlled to be 1: 30, performing ultrasonic extraction for 40min at 40 ℃ under the condition that the ultrasonic power is 350W, centrifuging for 2min at 10000prm, taking supernatant, performing rotary evaporation to remove ethanol, adding deionized water with the mass being 10 times of that of the ionic liquid as an anti-solvent, destroying the interaction between the ionic liquid and the zeaxanthin, reducing the solubility of the zeaxanthin, performing secondary centrifugal separation for 20min at 4 ℃ and 10000rpm, wherein the supernatant is an aqueous solution containing the ionic liquid, the zeaxanthin is deposited at the bottom of a centrifugal tube, repeatedly adding deionized water as the anti-solvent, performing secondary centrifugal separation for 2-3 times, and mixing precipitates obtained in the secondary centrifugal separation until the precipitation of the forskolin is not generated in the supernatant, and analyzing the content of the zeaxanthin extracted under the condition of the ionic liquid with different concentrations by adopting the same HPLC method as that in the example 1.

The results of the effect of different concentrations of ionic liquid on the extraction of zeaxanthin from lycium barbarum are shown in fig. 4; as can be seen from FIG. 4, the zeaxanthin content increases and then decreases with the increase of the ionic liquid concentration, and at 0.1g/ml, the zeaxanthin content reaches the maximum, and then the ionic liquid concentration increases, and the zeaxanthin content decreases, which may be caused by the fact that the extraction process is influenced by the increase of the viscosity of the extraction solution system with the increase of the ionic liquid concentration.

Example 4

This example compares the influence of different ultrasonic time on extracting zeaxanthin in matrimony vine, and the specific process is as follows:

weighing 0.2g of freeze-dried medlar powder, and respectively adding the freeze-dried medlar powder into an ethanol solution containing 0.10g/ml of [ Hmim ] OAC ionic liquid and 6 wt% of KOH, wherein the material-liquid ratio is controlled to be 1: 30, ultrasonic extracting for different time (10min, 20min, 30min, 40min, 50min and 60min) at 40 ℃ and under the condition that the ultrasonic power is 350W, centrifuging for 2min at 10000prm, taking supernatant, then performing rotary evaporation to remove ethanol, adding deionized water with the mass 10 times of that of ionic liquid as an anti-solvent, destroying the interaction between the ionic liquid and the zeaxanthin, reducing the solubility of the zeaxanthin, then performing secondary centrifugal separation for 20min at 4 ℃ and 10000rpm, wherein the supernatant is aqueous solution containing the ionic liquid, and the zeaxanthin is deposited at the bottom of the centrifuge tube, deionized water is repeatedly added as an anti-solvent again, and the centrifuge separation is carried out for 2-3 times for the second time until no precipitate is generated by dripping the forskolin phenol into the supernatant, the precipitates obtained in the centrifuge separation are combined, and the content of the zeaxanthin extracted under different ultrasonic time is analyzed by adopting the HPLC method which is the same as that in the embodiment 1.

The results of the effect of different ultrasound extraction times on the extraction of zeaxanthin from lycium barbarum are shown in fig. 5; as can be seen from fig. 5, the zeaxanthin content gradually increased with increasing ultrasound time, reaching a maximum at 40 min; further extension of the extraction time, the zeaxanthin content instead decreases, probably due to the destruction of zeaxanthin by the longer ultrasound action process.

Example 5

In this embodiment, the influence of different feed liquid ratios on the extraction of zeaxanthin from lycium barbarum is compared, and the specific process is as follows:

weighing 0.2g of freeze-dried medlar powder, respectively adding the freeze-dried medlar powder into an ethanol solution containing 0.10g/ml of [ Hmim ] OAC ionic liquid and 6 wt% of KOH, and respectively controlling the material-liquid ratio to be 1: 20. 1: 30. 1: 40. 1: 50 and 1: 60, performing ultrasonic extraction for 40min at 40 ℃ under the condition that the ultrasonic power is 350W, centrifuging for 2min at 10000prm, taking supernatant, performing rotary evaporation to remove ethanol, adding deionized water with the mass being 10 times of that of the ionic liquid as an anti-solvent, destroying the interaction between the ionic liquid and the zeaxanthin, reducing the solubility of the zeaxanthin, performing secondary centrifugal separation for 20min at 4 ℃ and 10000rpm, wherein the supernatant is an aqueous solution containing the ionic liquid, the zeaxanthin is deposited at the bottom of a centrifugal tube, repeatedly adding deionized water as the anti-solvent, performing secondary centrifugal separation for 2-3 times, and mixing precipitates obtained in the secondary centrifugal separation until the formol is dropwise added into the supernatant to avoid precipitation, and analyzing the content of the zeaxanthin extracted under different material-liquid ratios by adopting the same HPLC method as that of the example 1.

The results of the effect of different feed liquid ratios on the extraction of zeaxanthin from lycium barbarum are shown in fig. 6; as can be seen from FIG. 6, the zeaxanthin content increases with the feed-to-liquid ratio, and when the liquid-to-liquid ratio is larger than 1:40, the effect on the zeaxanthin content is not very different, so that 1:40 is the most suitable feed-to-liquid ratio.

Example 6

This embodiment has compared the influence of different ultrasonic power to extracting zeaxanthin in the matrimony vine, and the specific process is as follows:

weighing 0.2g of freeze-dried medlar powder, and respectively adding the freeze-dried medlar powder into an ethanol solution containing 0.10g/ml of [ Hmim ] OAC ionic liquid and 6 wt% of KOH, wherein the material-liquid ratio is controlled to be 1:40, performing ultrasonic extraction for 40min at 40 ℃ under the condition of adopting different ultrasonic powers (150W, 300W, 350W, 420W, 600W and 700W), then centrifuging for 2min at 10000prm, then taking supernatant, then performing rotary evaporation to remove ethanol, adding deionized water with the mass 10 times of that of ionic liquid as an anti-solvent, destroying the interaction between the ionic liquid and the zeaxanthin, reducing the solubility of the zeaxanthin, then performing secondary centrifugal separation for 20min at 4 ℃ and 10000rpm, wherein the supernatant is aqueous solution containing the ionic liquid, and the zeaxanthin is deposited at the bottom of the centrifugal tube, deionized water is repeatedly added as an anti-solvent again, and the centrifugal separation is carried out for 2-3 times for the second time until no precipitate is generated by dripping the forskolin phenol into the supernatant, the precipitates obtained in the second centrifugal separation are combined, and the content of the zeaxanthin extracted under different ultrasonic power conditions is analyzed by adopting the HPLC method which is the same as that in the embodiment 1.

The results of the effect of different ultrasonic powers on the extraction of zeaxanthin from lycium barbarum are shown in fig. 7; as can be seen from fig. 7, the zeaxanthin extraction amount is low when the ultrasonic power is below 400W, and the possible reason is that the ultrasonic intensity acting on the material is insufficient and the material cannot be sufficiently subjected to the ultrasonic action when the output power is low; along with the increase of the output power of the ultrasonic wave, the molecular diffusion in the material is increased, the extracted carotenoid is increased, and the maximum carotenoid is reached at 420 w; high power can cause some loss to the machine; the production cost is also increased correspondingly; therefore, the ultrasonic output power is preferably about 420W.

Comparative example 1

The comparative example provides a method for extracting zeaxanthin from Chinese wolfberry by using ionic liquid, which comprises the following specific steps:

weighing 0.2g of freeze-dried medlar powder, and mixing the raw materials in a ratio of 1: 30, ultrasonic extracting at 40 deg.C and 350W for 40min, centrifuging at 10000prm for 2min, adding 6ml saturated solution of sodium chloride and 12ml methyl tert-butyl ether into the extractive solution, transferring carotenoid to ether layer, collecting supernatant, extracting the lower layer with methyl tert-butyl ether for 2-3 times, mixing the supernatants, concentrating on rotary evaporator, and performing HPLC analysis after constant volume.

The detection result is shown in fig. 8, the yield of both the zeaxanthin and the zeaxanthin dipalmitate is low, and the number of the mixed peaks is large, wherein the yield of the zeaxanthin is 2.06mg/100 g; the extraction method is characterized in that alkali is not added in the extracting solution, the ionic liquid and the ethanol composite solvent cannot effectively extract the lycium barbarum carotenoid, and the extraction efficiency is low probably because the carotenoid in the lycium barbarum mainly comprises zeaxanthin esters which do not have hydrogen bond binding sites and cannot be combined with the zeaxanthin esters.

Comparative example 2

The comparative example provides a method for extracting zeaxanthin from Chinese wolfberry by using ionic liquid, which comprises the following specific steps:

weighing 0.5g of freeze-dried medlar powder, adding 6 wt% of KOH-ethanol solution, then filling nitrogen, saponifying for 6 hours in the dark, centrifuging to remove supernatant, and mixing the materials according to a material-liquid ratio of 1: 30, ultrasonic extracting at 40 ℃ for 40min under the condition of ultrasonic power of 350W, centrifuging at 10000prm for 2min, adding 6ml of saturated sodium chloride solution and 12ml of methyl tert-butyl ether into the extracting solution, transferring the carotenoid to an ether layer, collecting supernatant, repeatedly extracting the lower layer with the methyl tert-butyl ether for 2-3 times, combining the supernatants, concentrating on a rotary evaporator, and performing HPLC analysis after constant volume is reached.

The detection result is shown in fig. 9, and the method of firstly saponifying and then extracting the ionic liquid can not effectively extract the carotene in the lycium barbarum, wherein the yield of the zeaxanthin is 1.67mg/100 g; the reason for this is probably that the subsequent extraction cannot be efficiently performed because the carotenoid esters in Lycium barbarum cannot be saponified to free form under mild conditions due to the thicker cell walls of the plants of Lycium barbarum.

Comparative example 3

The comparative example provides a method for extracting zeaxanthin from medlar by adopting a traditional organic solvent, which comprises the following specific steps:

weighing 0.2g of freeze-dried medlar powder, and adding the powder into 16mL of the mixture with the volume ratio of 2: 1: 1 in n-hexane, acetone and ethanol (0.1% BHT), performing ultrasonic extraction at 40 deg.C and ultrasonic power of 350W for 40min, centrifuging at 4 deg.C and 10000prm for 4min, and evaporating at 35 deg.C on rotary evaporator; dissolving the residue in 2ml of methyl tert-butyl ether, adding 2ml of 15 w/v% KOH-methanol solution, introducing nitrogen, and saponifying in the dark for 6 h; after saponification, separation was carried out using 2ml of methyl t-butyl ether and 4ml of a saturated solution of sodium chloride, and the supernatant was collected, and the lower aqueous layer was extracted 3 times with 4ml of MTBE repeatedly. The supernatants were mixed and evaporated to dryness at 35 ℃ on a rotary evaporator, and 10ml of dichloromethane was added to the volume for HPLC analysis, and the detection results are shown in FIG. 10.

By comparing the high performance liquid chromatograms of the traditional organic solvent (figure 10) and the ionic liquid for extracting the carotenoid in the medlar (figure 2) in the comparative example, it can be seen that the composition content of the medlar carotenoid extracted by the two methods is not different, and the zeaxanthin content in the medlar can reach 93% of the total carotenoid.

As shown in the following table 1, the content of zeaxanthin obtained by extraction with ionic liquid under optimized conditions provided by the embodiment of the invention is 296.45mg/100g, the extraction yield is improved by 23.08% compared with the traditional method, and the extraction and saponification performed in the experiment are performed simultaneously, so that the problem of complicated steps in the traditional extraction can be solved, and the extraction time is greatly shortened.

TABLE 1 comparison of the extraction of ionic liquids of the present invention with conventional organic solvents

It should be noted that the above examples are only for further illustration and description of the technical solution of the present invention, and are not intended to further limit the technical solution of the present invention, and the method of the present invention is only a preferred embodiment, and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.