Method for separating stigmasterol from mixed phytosterol

Abstract

The invention discloses a method for separating stigmasterol from mixed phytosterol. The method comprises the following steps: carrying out fractional extraction on a raw material solution containing mixed phytosterol by using an extracting agent containing ionic liquid to obtain an extracting solution containing stigmasterol; carrying out back extraction on the extract liquor containing stigmasterol to obtain stigmasterol; wherein the mixed phytosterol comprises stigmasterol and at least one of beta-sitosterol, campesterol and rapeseed sterol, the ionic liquid is composed of choline cations and anions, and the anions comprise amino acid anions and / or carboxylic acid anions. The method adopts the extraction agent with good biocompatibility, has the characteristics of high separation efficiency, high product purity, simple process flow, greenness, environmental protection and the like, and is suitable for industrial production.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of chemical separation technology, and particularly relates to a method for separating stigmasterol from mixed phytosterols. BACKGROUND

[0002] Phytosterols are a kind of natural active substances containing triterpene sterol nucleus structure, having strong physiological activity and surface activity, and are widely used in medicine, food, cosmetics, optical products, feed, chemical industry, textile and other fields. Stigmasterol is a typical representative of phytosterols, and is widely present in various plants and deodorized distillates of plant oil refining, has multiple physiological activities, has obvious functions of reducing human serum cholesterol, preventing and treating cerebral hemorrhage and arteriosclerosis, and can be used for synthesizing adrenal cortex hormone and luteal hormone drugs.

[0003] Natural phytosterols are often a mixture of multiple sterols, and the most content phytosterols mainly include sitosterol, stigmasterol, campesterol and brassicasterol. The structural differences of these phytosterols are only in the differences of double bond and methyl / ethyl branch on the alkyl chain, so the phytosterols not only have similar structures, but also have very small differences in physicochemical properties, so it is very difficult to enrich a single phytosterol from the phytosterol mixture, and a high-yield and good separation effect purification technology needs to be selected.

[0004]

[0005] The current research on phytosterols is mainly focused on the extraction of phytosterols. The reported methods for the separation and purification of phytosterols mainly include recrystallization, chromatographic separation, adsorption and crystallization. Xu et al.

Xu WL, Huang Y B, Qian J H, et al. Separation and purification of stigmasterol and beta-sitosterol from phytosterol mixtures by solvent crystallization method [J]. Separation and Purification Technology, 2005, 41(2): 173-178

Srividya N, Heidorn D B, Lange B M. Rapid purification of gram quantities of beta-sitosterol from a commercial phytosterol mixture [J]. BMC research notes, 2014, 7: 182

Chuang Y, Ju Y. Separation of campesterol and beta-sitosterol from a sterol mixture [J]. Separation Science and Technology, 2006, 41(13): 3027-3038

[0006] As a new type of "green" solvent, ionic liquid has the advantages of low volatility, thermal stability, wide liquid range, and designability, and is widely used as a solvent and reaction medium. However, in recent years, it has been found that some ionic liquids used more frequently are non-biodegradable and toxic to the environment and ecological system, and are often used for the extraction of some natural products and eventually used as food additives for humans or animals, so their toxicity to organisms cannot be ignored. Therefore, it is also necessary to design efficient, low-toxic and biocompatible separation media. SUMMARY

[0007] In order to solve one of the above technical problems in the prior art, the present application provides a method for separating stigmasterol from mixed phytosterols. The method is based on the weak polarity difference and double bond difference between stigmasterol and beta-sitosterol, campesterol and brassicasterol, and uses an extractant containing a specific type of ionic liquid to realize the enrichment of stigmasterol in mixed phytosterols through molecular weak interaction forces such as van der Waals and pi-pi. Compared with the existing method, the extractant used in the method of the present application has good biocompatibility and high separation efficiency, and the process has the advantages of simple operation, large processing capacity, easy recycling of extractant, etc.

[0008] The technical scheme of the present application is as follows:

[0009] A method for separating stigmasterol from mixed phytosterols, comprising the following steps:

[0010] The raw material liquid containing mixed phytosterols is subjected to fractional extraction with an extractant containing ionic liquid to obtain an extract liquid containing stigmasterol; the extract liquid containing stigmasterol is subjected to back extraction to obtain stigmasterol;

[0011] The mixed phytosterols include stigmasterol and at least one selected from beta-sitosterol, campesterol and brassicasterol, the ionic liquid is composed of choline cation and anion, and the anion includes amino acid anion and / or carboxylic acid anion.

[0012] The extractant used in the present application has excellent biocompatibility and is green and environmentally friendly. In addition, the extractant of the present application has high separation efficiency and high selectivity for stigmasterol, and a small amount of ionic liquid can be used to separate high-purity stigmasterol.

[0013] According to some embodiments of the present application, in the ionic liquid, the choline-based cation comprises a choline cation or a choline cation substituted with one or more substituents selected from alkyl, alkenyl, cyano, thiocyanato, sulfone, carbonyl. In some embodiments, the alkyl is a C1-C4 straight chain or branched alkyl, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, and the like. In some embodiments, the alkyl is a C2-C4 straight chain alkyl. In some embodiments, the alkenyl is a C2-C4 alkenyl, such as ethenyl, propenyl, butenyl, and the like.

[0014] According to some embodiments of the present application, in the ionic liquid, the amino acid anion is selected from one or more of a neutral amino acid anion, a basic amino acid anion, an acidic amino acid anion.

[0015] In some embodiments, the neutral amino acid anion is selected from one or more of a glycine anion, a proline anion, an alanine anion, a leucine anion, a valine anion, a phenylalanine anion.

[0016] In some embodiments, the basic amino acid is selected from one or more of a tryptophan anion, an asparagine anion, a glutamine anion, a lysine anion, an arginine anion.

[0017] In some embodiments, the acidic amino acid is selected from one or more of a cysteine anion, a methionine anion, a glutamic acid anion.

[0018] In some embodiments, the amino acid anion is substituted with one or more substituents selected from hydroxyl, C1-C4 straight chain or branched alkyl, C1-C4 straight chain or branched alkenyl.

[0019] In some embodiments, the carboxylic acid anion is a C2-C22 saturated or unsaturated carboxylic acid anion. In some embodiments, the carboxylic acid anion is a C8-C22 saturated or unsaturated carboxylic acid anion. In the present application, the carboxylic acid anion includes, but is not limited to, one or more of a n-octanoate anion, a n-decanoate anion, an undecanoate anion, a dodecanoate anion, a myristate anion, a palmitate anion, a laurate anion, a stearate anion, an oleate anion, a linoleate anion. In some embodiments, the carboxylic acid anion is one or more of a n-decanoate anion, a myristate anion, a palmitate anion.

[0020] In some embodiments, the extractant is an ionic liquid. In some embodiments, the extractant is a mixture of an ionic liquid and a polar solvent.

[0021] In some embodiments, the mixture of the ionic liquid and the polar solvent has a molar percentage of the ionic liquid in the range of 0.01% to 50%, for example, 0.01%, 0.05%, 0.1%, 0.2%, 0.3%, 0.5%, 0.8%, 1%, 2%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, 32%, 35%, 38%, 40%, 42%, 45%, 48%, 50%.

[0022] In some embodiments, the mixture of the ionic liquid and the polar solvent has a molar percentage of the ionic liquid in the range of 0.05% to 40%. In some embodiments, the mixture of the ionic liquid and the polar solvent has a molar percentage of the ionic liquid in the range of 0.1% to 30.0%. In some embodiments, the mixture of the ionic liquid and the polar solvent has a molar percentage of the ionic liquid in the range of 0.2% to 15.0%. In some embodiments, the mixture of the ionic liquid and the polar solvent has a molar percentage of the ionic liquid in the range of 0.3% to 10.0%.

[0023] In some embodiments, the mixture of the ionic liquid and the polar solvent has the polar solvent selected from one or more of water, oxygen-containing organic solvents, phosphorus-containing organic solvents, nitrogen-containing organic solvents, and sulfur-containing organic solvents. In some embodiments, the polar solvent is selected from one or more of alcohols, nitriles, amides, sulfones, sulfoxides organic solvents. In some specific embodiments, the polar solvent is selected from at least one of water, methanol, ethylene glycol, 1,3-propanediol, glycerol, dimethyl sulfoxide, sulfolane, acetonitrile, N-methylpyrrolidone, N-methylformamide, N,N-dimethylformamide. In some embodiments, the polar solvent is selected from N,N-dimethylformamide and dimethyl sulfoxide. In some preferred embodiments, the polar solvent is dimethyl sulfoxide.

[0024] According to some embodiments of the present application, the ionic liquid is selected from one or more of choline n-decanoate, choline myristate, choline palmitate, choline glycinate, choline lysinate.

[0025] According to some embodiments of the present application, the extractant is selected from one or more of choline n-decanoate, choline myristate, choline palmitate, choline glycinate, choline lysinate, a mixture of choline n-decanoate and dimethyl sulfoxide, a mixture of choline myristate and dimethyl sulfoxide, a mixture of choline palmitate and dimethyl sulfoxide, a mixture of choline glycinate and dimethyl sulfoxide, a mixture of choline lysinate and dimethyl sulfoxide, a mixture of choline n-decanoate and N,N-dimethylformamide.

[0026] According to some embodiments of the present application, the feedstock solution further comprises a feedstock solvent, which comprises a non-polar organic solvent and optionally a polar modifier. In some embodiments, the non-polar organic solvent comprises one or more of C6-C12 linear alkanes, C6-C12 branched alkanes, C6-C12 cyclic alkanes, C1-C6 halogenated alkanes. In some specific embodiments, the non-polar organic solvent comprises one or more of n-hexane, n-heptane, n-octane, n-nonane, n-decane, 2,2,4-trimethylpentane, isooctane, isodecane, cyclohexane, methylcyclohexane, trichloromethane. In some embodiments, the non-polar organic solvent is n-hexane.

[0027] According to some embodiments of the present application, the polar modifier comprises an alcoholic organic solvent. In some embodiments, the polar modifier comprises C1-C4 monohydric alcohol and / or C2-C4 polyhydric alcohol. In some specific embodiments, the polar modifier comprises one or more of methanol, ethanol, ethylene glycol, 1,3-propanediol, glycerol. In some embodiments, the polar modifier is methanol.

[0028] According to some embodiments of the present application, the polar modifier accounts for 0.1%-10.0% of the total volume of the non-polar organic solvent and the polar modifier, for example 0.1%, 0.2%, 0.5%, 0.8%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, 6.5%, 7.0%, 7.5%, 8.0%, 8.5%, 9.0%, 9.5%, 10.0% or any value therebetween, preferably 0.5%-5.0%.

[0029] According to some embodiments of the present application, the mixed phytosterol comprises 10wt%-40wt% of stigmasterol, for example 10wt%, 12wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, 40wt% or any value therebetween. In some embodiments, the mixed phytosterol comprises 20wt%-30wt% of stigmasterol.

[0030] According to some embodiments of the present application, the total concentration of phytosterols in the raw material solution is 1.0 g / L to 100.0 g / L, for example, 1.0 g / L, 2.0 g / L, 3.0 g / L, 5.0 g / L, 8 g / L, 10.0 g / L, 12.0 g / L, 15.0 g / L, 18.0 g / L, 20.0 g / L, 25.0 g / L, 30.0 g / L, 35.0 g / L, 40.0 g / L, 45.0 g / L, 50.0 g / L, 55.0 g / L, 60.0 g / L, 65.0 g / L, 70.0 g / L, 75.0 g / L, 80.0 g / L, 85.0 g / L, 90.0 g / L, 95.0 g / L, 100.0 g / L, or any value therebetween, preferably 5.0 g / L to 50.0 g / L.

[0031] According to some embodiments of the present application, the mixed phytosterols include stigmasterol, β-sitosterol, campesterol, and optionally brassicasterol.

[0032] According to some embodiments of the present application, the mixed phytosterols include stigmasterol, β-sitosterol, campesterol, and brassicasterol.

[0033] According to some embodiments of the present application, the content of β-sitosterol in the mixed phytosterols is 30 wt% to 50 wt%, preferably 40 wt% to 45 wt%.

[0034] According to some embodiments of the present application, the content of campesterol in the mixed phytosterols is 10 wt% to 40 wt%, preferably 20 wt% to 30 wt%.

[0035] According to some embodiments of the present application, the content of brassicasterol in the mixed phytosterols is 0 to 5 wt%, preferably 0.1 to 2 wt%.

[0036] According to some embodiments of the present application, the mass content ratio of β-sitosterol to stigmasterol in the mixed phytosterols is (1.0-2.0):1. According to some embodiments of the present application, the mass content ratio of campesterol to stigmasterol in the mixed phytosterols is (0.5-1.5):1. According to some embodiments of the present application, the mass content ratio of brassicasterol to stigmasterol in the mixed phytosterols is (0.005-0.02):1.

[0037] According to some embodiments of the present application, the flow ratio of extractant to feed liquid in the fractional extraction is (5-25): 1, such as 5: 1, 8: 1, 10: 1, 12: 1, 15: 1, 18: 1, 20: 1, 22: 1, 25: 1, etc. In some embodiments, the flow ratio of extractant to feed liquid in the fractional extraction is (10-25): 1. In some embodiments, the flow ratio of extractant to feed liquid in the fractional extraction is (15-22): 1. In some embodiments, the flow ratio of extractant to feed liquid in the fractional extraction is (18-20): 1.

[0038] According to some embodiments of the present application, the flow ratio of extractant to feed liquid in the fractional extraction is (0.1-10.0): 1, such as 0.1: 1, 0.5: 1, 0.8: 1, 1.0: 1, 1.2: 1, 1.5: 1, 1.8: 1, 2.0: 1, 3.0: 1, 4.0: 1, 5.0: 1, 6.0: 1, 7.0: 1, 8.0: 1, 9.0: 1, 10.0: 1, etc. In some embodiments, the flow ratio of extractant to feed liquid in the fractional extraction is (0.5-8.0): 1. In some embodiments, the flow ratio of extractant to feed liquid in the fractional extraction is (1.0-5.0): 1.

[0039] According to some embodiments of the present application, the extractant comprises a non-polar organic solvent and optionally a polarity modifier. In some embodiments, the non-polar organic solvent comprises one or more of a C6-C12 linear alkane, a C6-C12 branched alkane, a C6-C12 cyclic alkane, a C1-C6 haloalkane. In some specific embodiments, the non-polar organic solvent comprises one or more of n-hexane, n-heptane, n-octane, n-nonane, n-decane, 2,2,4-trimethylpentane, isooctane, isodecane, cyclohexane, methylcyclohexane, trichloromethane. In some embodiments, the non-polar organic solvent is n-hexane. In some embodiments, the polarity modifier comprises an alcoholic organic solvent. In some embodiments, the polarity modifier comprises a C1-C4 monohydric alcohol and / or a C2-C4 polyhydric alcohol. In some specific embodiments, the polarity modifier comprises one or more of methanol, ethanol, ethylene glycol, 1,3-propanediol, glycerol. In some embodiments, the polarity modifier is methanol.

[0040] According to some embodiments of the present application, the extractant is the same as the feed solvent species in the feed liquid.

[0041] According to some embodiments of the present application, the fractional extraction is a multi-stage fractional extraction. According to some embodiments of the present application, the fractional extraction comprises an extraction section and a washing section. The extraction section can be 15-50 stages, such as 15, 18, 20, 22, 25, 30, 35, 40, 45, 50 stages, etc. In some embodiments, the extraction section is 15-40 stages. In some embodiments, the extraction section is 15-35 stages. In some embodiments, the extraction section is 20-30 stages. The washing section can be 25-60 stages, such as 25, 30, 35, 40, 45, 50, 55, 60 stages, etc. In some embodiments, the washing section is 25-50 stages. In some embodiments, the washing section is 30-45 stages. In some embodiments, the washing section is 30-40 stages.

[0042] According to some embodiments of the present application, the fractional extraction comprises an extraction section and a washing section. The extractant enters the fractional extraction system from the first stage of the extraction section, the raw material liquid enters the fractional extraction system from the last stage of the extraction section, the washing agent enters the fractional extraction system from the first stage of the washing section, and the washing agent is combined with the raw material liquid at the last stage of the extraction section to enter the extraction section. The extraction phase and the raw material phase are subjected to multi-stage countercurrent contact, the raffinate enriched in other phytosterols flows out from the first stage of the extraction section; the extract liquid enriched in stigmasterol flows out from the first stage of the washing section, and stigmasterol is obtained through back extraction, water washing, and vacuum rectification. The extractant is recovered and recycled. The mixed phytosterols after removing most of the stigmasterol in the raffinate can be used for extracting other high-purity phytosterols, food additives, and livestock feed additives, etc., to achieve full utilization of the mixed phytosterols.

[0043] According to some embodiments of the present application, the operating temperature of the fractional extraction is 10-70℃, such as 10℃, 15℃, 20℃, 25℃, 30℃, 40℃, 50℃, 60℃, 70℃, or any value therebetween. If the extraction temperature is too low, the solution viscosity is large, which is not conducive to mass transfer. If the extraction temperature is too high, the organic solvent will start to volatilize, and the mutual solubility of the two phases increases, which is not conducive to extraction. In some preferred embodiments, the operating temperature of the fractional extraction is 20-50℃.

[0044] According to some embodiments of the present application, the back extraction solvent used in back extraction is the same as the raw material solvent in the raw material liquid.

[0045] According to some embodiments of the present application, the method further comprises: vacuum concentrating the back extraction phase obtained after back extraction to obtain stigmasterol.

[0046] Compared with the prior art, the present application has the following beneficial effects:

[0047] 1.The method of the present application adopts fractional extraction method, selects suitable extractant, and has high selectivity for separating stigmasterol in mixed phytosterol; and the ionic liquid used as the extractant contains choline cation, amino acid or carboxylic acid anion, which not only has high selectivity for separating stigmasterol, but also has good biodegradability and biocompatibility, reduces the influence on human body and environment, and has wide green application prospect.

[0048] 2.The method of the present application has the advantages of low energy consumption, high efficiency, simple operation, safe process, low cost and the like, and is suitable for industrial production.

[0049] 3.The method of the present application has high separation efficiency, and the separated stigmasterol product has high purity, which can reach more than 80%. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical scheme and advantages of the present application clearer and more apparent, the present application is further described in detail below in combination with embodiments. The specific embodiments described herein are only used to explain the present application and do not constitute any limitation on the present application.

[0051] In the following experiments of the present application, the reagents used, unless otherwise specified, are conventional commercially available products or reagents prepared according to conventional methods, and the methods used in the experiments, unless otherwise specified, are conventional experimental methods. The instruments used in the experiments, unless otherwise specified, can be obtained through commercial channels.

[0052] As a specific embodiment of the present application, the method for separating stigmasterol from mixed phytosterol comprises the following steps:

[0053] (S1) dissolving mixed phytosterol raw material in a raw material solvent according to a certain proportion to obtain a raw material solution;

[0054] (S2) using an extractant containing ionic liquid to perform multi-stage fractional extraction on the raw material solution, the extractant enters the fractional extraction system from the first stage of the extraction section, the raw material solution enters the fractional extraction system from the last stage of the extraction section, and the same type of washing agent as the raw material solvent enters the fractional extraction system from the first stage of the washing section, and is combined with the raw material solution at the last stage of the extraction section to enter the extraction section, after multi-stage countercurrent contact, the extractant flows out from the first stage of the washing section, and the raffinate flows out from the first stage of the extraction section; collecting the extractant, performing back extraction and concentration to obtain stigmasterol and recyclable extractant; the raffinate contains mixed phytosterol after removing most of the stigmasterol, which can be used for extracting other high-purity phytosterols, food additives, livestock feed additives and the like, and realizes full utilization of mixed phytosterol.

[0055] In the following examples and comparative examples of the present application, high performance liquid chromatography (HPLC) is used to analyze the concentration of each phytosterol component. The specific HPLC analysis conditions are as follows: Waters Sunfire C18 column (4.6 mm ID x 250 mm, particle size 5 μm), mobile phase is pure methanol, flow rate is 1 mL / min, column temperature is 30 °C, and ultraviolet detection wavelength is 210 nm.

[0056] In the following examples and comparative examples, the calculation method of the yield and purity of stigmasterol is as follows:

[0057] Stigmasterol yield = mass of stigmasterol in product / mass of stigmasterol in raw material x 100%;

[0058] Stigmasterol purity = mass of stigmasterol in product / total mass of product x 100%.

[0059] In the mixed phytosterol used in the following examples and comparative examples of the present application, the mass content ratio of β-sitosterol and stigmasterol is about 1.5:1, the mass content ratio of campesterol and stigmasterol is about 1:1, and the mass content ratio of brassicasterol and stigmasterol is about 0.01:1.

[0060] Example 1

[0061] The mixed phytosterol raw material (in which the content of stigmasterol is 26.0 wt.%) is dissolved in a raw material solvent prepared from n-hexane:methanol = 98:2 (v / v) to prepare a solution of 4.0 g / L as a raw material liquid. Choline n-decanoate-dimethyl sulfoxide (the molar fraction of choline n-decanoate is 0.3 mol%) is used as an extractant, n-hexane:methanol = 98:2 (v / v) is used as a washing agent, and fractionation extraction is carried out at 30 °C. The flow ratio of the extractant, the washing agent, and the raw material liquid is 19.6:3.1:1, the extraction section has a total of 28 stages, and the washing section has a total of 40 stages. The extractant enters the fractionation extraction system from the first stage of the extraction section, the raw material liquid enters the fractionation extraction system from the last stage of the extraction section, and the washing agent enters the fractionation extraction system from the first stage of the washing section. The stigmasterol-rich extract liquid flows out from the first stage of the washing section, and the other component-rich raffinate liquid flows out from the first stage of the extraction section, and the extract liquid and the raffinate liquid are collected.

[0062] The extract liquid is back-extracted using n-hexane:methanol = 98:2 (v / v), and the back-extraction phase is concentrated under vacuum to obtain a stigmasterol product, and the purity of the stigmasterol is 91.44 wt.%. The ionic liquid phase after back-extraction can be concentrated and recycled for use.

[0063] Example 2

[0064] A mixed phytosterol feedstock (containing 26.0 wt.% of stigmasterol) was dissolved in a feed solvent prepared from n-hexane:methanol = 98:2 (v / v) to prepare a solution of 4.0 g / L as a feed liquid. Fractional extraction was carried out at 30°C with choline myristate-dimethyl sulfoxide (mole fraction of choline myristate 0.3 mol%) as an extractant, n-hexane:methanol = 98:2 (v / v) as a scrubber. The flow ratio of the extractant, the scrubber and the feed liquid was 19.5:3.2:1, and the extraction section had 28 stages and the scrubbing section had 40 stages. The extractant entered the fractional extraction system from the first stage of the extraction section, the feed liquid entered the fractional extraction system from the last stage of the extraction section, and the scrubber entered the fractional extraction system from the first stage of the scrubbing section. The stigmasterol-rich extract liquid flowed out from the first stage of the scrubbing section, and the other component-rich raffinate liquid flowed out from the first stage of the extraction section, and the extract liquid and the raffinate liquid were collected.

[0065] The extract liquid was back-extracted with n-hexane:methanol = 98:2 (v / v), and the back-extraction phase was concentrated under vacuum to obtain a stigmasterol product, and the purity of stigmasterol was 90.47 wt.%. The ionic liquid phase after back-extraction was concentrated, and the ionic liquid phase could be recycled.

[0066] Example 3

[0067] A mixed phytosterol feedstock (containing 26.0 wt.% of stigmasterol) was dissolved in a feed solvent prepared from n-hexane:methanol = 98:2 (v / v) to prepare a solution of 4.0 g / L as a feed liquid. Fractional extraction was carried out at 30°C with choline myristate-dimethyl sulfoxide (mole fraction of choline myristate 0.3 mol%) as an extractant, n-hexane:methanol = 98:2 (v / v) as a scrubber. The flow ratio of the extractant, the scrubber and the feed liquid was 19.5:3.2:1, and the extraction section had 28 stages and the scrubbing section had 40 stages. The extractant entered the fractional extraction system from the first stage of the extraction section, the feed liquid entered the fractional extraction system from the last stage of the extraction section, and the scrubber entered the fractional extraction system from the first stage of the scrubbing section. The stigmasterol-rich extract liquid flowed out from the first stage of the scrubbing section, and the other component-rich raffinate liquid flowed out from the first stage of the extraction section, and the extract liquid and the raffinate liquid were collected.

[0068] The extract liquid was back-extracted with n-hexane:methanol = 98:2 (v / v), and the back-extraction phase was concentrated under vacuum to obtain a stigmasterol product, and the purity of stigmasterol was 90.47 wt.%. The ionic liquid phase after back-extraction was concentrated, and the ionic liquid phase could be recycled.

[0069] Example 4

[0070] A mixed phytosterol feedstock (containing 26.0 wt.% of stigmasterol) was dissolved in a feedstock solvent prepared from n-hexane:methanol = 98:2 (v / v) to prepare a solution of 4.0 g / L as a feedstock solution. Fractional extraction was carried out at 30°C with choline lysinate-dimethyl sulfoxide (the molar fraction of choline lysinate was 10 mol%) as an extractant, n-hexane:methanol = 98:2 (v / v) as a washing agent. The flow ratio of the extractant, the washing agent and the feedstock solution was 20.0:1.7:1, and the extraction section had 21 stages and the washing section had 35 stages. The extractant entered the fractional extraction system from the first stage of the extraction section, the feedstock solution entered the fractional extraction system from the last stage of the extraction section, and the washing agent entered the fractional extraction system from the first stage of the washing section. The stigmasterol-rich extract flowed out from the first stage of the washing section, and the other component-rich raffinate flowed out from the first stage of the extraction section, and the extract and the raffinate were collected.

[0071] The extract was back-extracted with n-hexane:methanol = 98:2 (v / v), and the back-extraction phase was concentrated under vacuum to obtain a stigmasterol product, and the purity of stigmasterol was 90.23 wt.%. The ionic liquid phase after back-extraction was concentrated, and the ionic liquid phase could be recycled.

[0072] Example 5

[0073] A mixed phytosterol feedstock (containing 26.0 wt.% of stigmasterol) was dissolved in a feedstock solvent prepared from n-hexane:methanol = 98:2 (v / v) to prepare a solution of 4.0 g / L as a feedstock solution. Fractional extraction was carried out at 30°C with choline lysinate-dimethyl sulfoxide (the molar fraction of choline lysinate was 10 mol%) as an extractant, n-hexane:methanol = 98:2 (v / v) as a washing agent. The flow ratio of the extractant, the washing agent and the feedstock solution was 20.0:1.7:1, and the extraction section had 21 stages and the washing section had 35 stages. The extractant entered the fractional extraction system from the first stage of the extraction section, the feedstock solution entered the fractional extraction system from the last stage of the extraction section, and the washing agent entered the fractional extraction system from the first stage of the washing section. The stigmasterol-rich extract flowed out from the first stage of the washing section, and the other component-rich raffinate flowed out from the first stage of the extraction section, and the extract and the raffinate were collected.

[0074] The extract was back-extracted with n-hexane:methanol = 98:2 (v / v), and the back-extraction phase was concentrated under vacuum to obtain a stigmasterol product, and the purity of stigmasterol was 90.23 wt.%. The ionic liquid phase after back-extraction was concentrated, and the ionic liquid phase could be recycled.

[0075] Example 6

[0076] A mixed phytosterol feedstock (containing 26.0 wt.% of stigmasterol) was dissolved in a feedstock solvent prepared from n-hexane:methanol = 98:2 (v / v) to prepare a solution of 4.0 g / L as a feedstock solution. Fractional extraction was carried out at 30°C with choline decanoate-dimethyl sulfoxide (the molar fraction of choline decanoate was 0.3 mol%) as an extractant, n-hexane:methanol = 98:2 (v / v) as a washing agent. The flow ratio of the extractant, the washing agent and the feedstock solution was 18.0:2.0:1, and the extraction section had 28 stages and the washing section had 40 stages. The extractant entered the fractional extraction system from the first stage of the extraction section, the feedstock solution entered the fractional extraction system from the last stage of the extraction section, and the washing agent entered the fractional extraction system from the first stage of the washing section. The stigmasterol-rich extract flowed out from the first stage of the washing section, the other component-rich raffinate flowed out from the first stage of the extraction section, and the extract and the raffinate were collected.

[0077] The extract was back-extracted with n-hexane:methanol = 98:2 (v / v), and the back-extraction phase was concentrated under vacuum to obtain a stigmasterol product, the purity of which was 85.50 wt.%. The ionic liquid phase after back-extraction was concentrated and recycled.

[0078] Example 7

[0079] A mixed phytosterol feedstock (containing 26.0 wt.% of stigmasterol) was dissolved in a feedstock solvent prepared from n-hexane:methanol = 98:2 (v / v) to prepare a solution of 4.0 g / L as a feedstock solution. Fractional extraction was carried out at 30°C with choline decanoate-dimethyl sulfoxide (the molar fraction of choline decanoate was 0.3 mol%) as an extractant, n-hexane:methanol = 98:2 (v / v) as a washing agent. The flow ratio of the extractant, the washing agent and the feedstock solution was 18.0:2.0:1, and the extraction section had 28 stages and the washing section had 40 stages. The extractant entered the fractional extraction system from the first stage of the extraction section, the feedstock solution entered the fractional extraction system from the last stage of the extraction section, and the washing agent entered the fractional extraction system from the first stage of the washing section. The stigmasterol-rich extract flowed out from the first stage of the washing section, the other component-rich raffinate flowed out from the first stage of the extraction section, and the extract and the raffinate were collected.

[0080] The extract was back-extracted with n-hexane:methanol = 98:2 (v / v), and the back-extraction phase was concentrated under vacuum to obtain a stigmasterol product, the purity of which was 85.50 wt.%. The ionic liquid phase after back-extraction was concentrated and recycled.

[0081] Example 8

[0082] A mixed phytosterol feedstock (containing 26.0 wt.% of stigmasterol) was dissolved in a feed solvent prepared from n-hexane:methanol = 96:4 (v / v) to prepare a solution of 4.0 g / L as a feed liquid. Fractional extraction was carried out at 30°C with choline n-decanoate-dimethyl sulfoxide (the molar fraction of choline n-decanoate was 0.3 mol%) as an extractant, n-hexane:methanol = 98:2 (v / v) as a scrubber. The flow ratio of the extractant, the scrubber and the feed liquid was 19.6:3.1:1, and the extraction section had 28 stages and the scrubbing section had 40 stages. The extractant entered the fractional extraction system from the first stage of the extraction section, the feed liquid entered the fractional extraction system from the last stage of the extraction section, and the scrubber entered the fractional extraction system from the first stage of the scrubbing section. The stigmasterol-rich extract liquid flowed out from the first stage of the scrubbing section, and the other component-rich raffinate liquid flowed out from the first stage of the extraction section, and the extract liquid and the raffinate liquid were collected.

[0083] The extract liquid was back-extracted with n-hexane:methanol = 96:4 (v / v), and the back-extraction phase was concentrated under vacuum to obtain a stigmasterol product, and the purity of stigmasterol was 91.36 wt.%. The ionic liquid phase after back-extraction was concentrated, and the ionic liquid phase could be recycled.

[0084] Example 9

[0085] A mixed phytosterol feedstock (containing 26.0 wt.% of stigmasterol) was dissolved in a feed solvent prepared from n-hexane:methanol = 98:2 (v / v) to prepare a solution of 10.0 g / L as a feed liquid. Fractional extraction was carried out at 30°C with choline n-decanoate-dimethyl sulfoxide (the molar fraction of choline n-decanoate was 0.3 mol%) as an extractant, n-hexane:methanol = 98:2 (v / v) as a scrubber. The flow ratio of the extractant, the scrubber and the feed liquid was 19.6:3.1:1, and the extraction section had 28 stages and the scrubbing section had 40 stages. The extractant entered the fractional extraction system from the first stage of the extraction section, the feed liquid entered the fractional extraction system from the last stage of the extraction section, and the scrubber entered the fractional extraction system from the first stage of the scrubbing section. The stigmasterol-rich extract liquid flowed out from the first stage of the scrubbing section, and the other component-rich raffinate liquid flowed out from the first stage of the extraction section, and the extract liquid and the raffinate liquid were collected.

[0086] The extract liquid was back-extracted with n-hexane:methanol = 98:2 (v / v), and the back-extraction phase was concentrated under vacuum to obtain a stigmasterol product, and the purity of stigmasterol was 90.28 wt.%. The ionic liquid phase after back-extraction was concentrated, and the ionic liquid phase could be recycled.

[0087] Example 10

[0088] A mixed phytosterol feedstock (containing 26.0 wt.% of stigmasterol) was dissolved in a feedstock solvent prepared from n-hexane:methanol = 98:2 (v / v) to prepare a solution of 4.0 g / L as a feedstock solution. Fractional extraction was carried out at 30°C with choline n-decanoate-N,N-dimethylformamide (mole fraction of choline n-decanoate 0.3 mol%) as an extractant, n-hexane:methanol = 98:2 (v / v) as a scrubber. The flow ratio of the extractant, the scrubber and the feedstock solution was 19.6:3.1:1, and the extraction section had 28 stages and the scrubbing section had 40 stages. The extractant entered the fractional extraction system from the first stage of the extraction section, the feedstock solution entered the fractional extraction system from the last stage of the extraction section, and the scrubber entered the fractional extraction system from the first stage of the scrubbing section. The stigmasterol-rich extract flowed out from the first stage of the scrubbing section, and the other component-rich raffinate flowed out from the first stage of the extraction section, and the extract and the raffinate were collected.

[0089] The extract was back-extracted with n-hexane:methanol = 98:2 (v / v), and the back-extraction phase was concentrated under vacuum to obtain a stigmasterol product, and the purity of stigmasterol was 83.12 wt.%. The ionic liquid phase after back-extraction was concentrated, and the ionic liquid phase could be recycled.

[0090] Example 11

[0091] A mixed phytosterol feedstock (containing 26.0 wt.% of stigmasterol) was dissolved in a feedstock solvent prepared from n-hexane:methanol = 98:2 (v / v) to prepare a solution of 4.0 g / L as a feedstock solution. Fractional extraction was carried out at 50°C with choline glycinate-dimethyl sulfoxide (mole fraction of choline glycinate 10 mol%) as an extractant, n-hexane:methanol = 98:2 (v / v) as a scrubber. The flow ratio of the extractant, the scrubber and the feedstock solution was 20.0:1.7:1, and the extraction section had 21 stages and the scrubbing section had 35 stages. The extractant entered the fractional extraction system from the first stage of the extraction section, the feedstock solution entered the fractional extraction system from the last stage of the extraction section, and the scrubber entered the fractional extraction system from the first stage of the scrubbing section. The stigmasterol-rich extract flowed out from the first stage of the scrubbing section, and the other component-rich raffinate flowed out from the first stage of the extraction section, and the extract and the raffinate were collected.

[0092] The extract was back-extracted with n-hexane:methanol = 98:2 (v / v), and the back-extraction phase was concentrated under vacuum to obtain a stigmasterol product, and the purity of stigmasterol was 88.46 wt.%. The ionic liquid phase after back-extraction was concentrated, and the ionic liquid phase could be recycled.

[0093] Example 12

[0094] A mixed phytosterol feedstock (containing 26.0 wt.% of stigmasterol) was dissolved in a feedstock solvent prepared from n-hexane:methanol = 98:2 (v / v) to prepare a solution of 4.0 g / L as a feedstock solution. Fractional extraction was carried out at 30°C with choline n-decanoate-dimethyl sulfoxide (2.0 mol% of choline n-decanoate) as an extractant, n-hexane:methanol = 98:2 (v / v) as a washing agent. The flow ratio of the extractant, the washing agent and the feedstock solution was 19.6:3.1:1, and the extraction section had 28 stages and the washing section had 40 stages. The extractant entered the fractional extraction system from the first stage of the extraction section, the feedstock solution entered the fractional extraction system from the last stage of the extraction section, and the washing agent entered the fractional extraction system from the first stage of the washing section. The stigmasterol-rich extract flowed out from the first stage of the washing section, and the other component-rich raffinate flowed out from the first stage of the extraction section, and the extract and the raffinate were collected.

[0095] The extract was back-extracted with n-hexane:methanol = 98:2 (v / v), and the back-extraction phase was concentrated under vacuum to obtain a stigmasterol product, and the purity of stigmasterol was 92.35 wt.%. The ionic liquid phase after back-extraction was concentrated, and the ionic liquid phase could be recycled.

[0096] Comparative Example 1

[0097] A mixed phytosterol feedstock (containing 26.0 wt.% of stigmasterol) was dissolved in a feedstock solvent prepared from n-hexane:methanol = 98:2 (v / v) to prepare a solution of 4.0 g / L as a feedstock solution. Fractional extraction was carried out at 30°C with N,N-dimethylformamide as an extractant, n-hexane:methanol = 98:2 (v / v) as a washing agent. The flow ratio of the extractant, the washing agent and the feedstock solution was 19.6:3.1:1, and the extraction section had 28 stages and the washing section had 40 stages. The extractant entered the fractional extraction system from the first stage of the extraction section, the feedstock solution entered the fractional extraction system from the last stage of the extraction section, and the washing agent entered the fractional extraction system from the first stage of the washing section. The stigmasterol-rich extract flowed out from the first stage of the washing section, and the other component-rich raffinate flowed out from the first stage of the extraction section, and the extract and the raffinate were collected.

[0098] The extract was back-extracted with n-hexane:methanol = 98:2 (v / v), and the back-extraction phase was concentrated under vacuum to obtain a stigmasterol product, and the purity of stigmasterol was 34.47 wt.%. The ionic liquid phase after back-extraction was concentrated, and the ionic liquid phase could be recycled.

[0099] Comparative Example 2

[0100] The mixed phytosterol raw material (containing 26.0 wt.% of stigmasterol) was dissolved in a raw material solvent prepared from n-hexane:methanol = 98:2 (v / v) to prepare a 4.0 g / L solution as a raw material liquid. Fractional extraction was carried out at 30°C with dimethyl sulfoxide as the extractant, n-hexane:methanol = 98:2 (v / v) as the washing agent. The flow ratio of the extractant, the washing agent and the raw material liquid was 19.5:3.2:1, the extraction section had a total of 28 stages, and the washing section had a total of 40 stages. The extractant entered the fractional extraction system from the first stage of the extraction section, the raw material liquid entered the fractional extraction system from the last stage of the extraction section, and the washing agent entered the fractional extraction system from the first stage of the washing section. The stigmasterol-rich extract liquid flowed out from the first stage of the washing section, the other component-rich raffinate liquid flowed out from the first stage of the extraction section, and the extract liquid and the raffinate liquid were collected.

[0101] The extract liquid was back-extracted using n-hexane:methanol = 98:2 (v / v), and the back-extraction phase was concentrated under vacuum to obtain a stigmasterol product with a purity of 30.06 wt.%. The ionic liquid phase after back-extraction was concentrated and recycled for use.

[0102] The above examples are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing examples, or make equivalent replacements for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the present application.

Claims

1. A method for separating stigmasterol from mixed phytosterols, comprising the following steps: fractionally extracting a raw material liquid containing mixed phytosterols with an extractant containing an ionic liquid to obtain an extract liquid containing stigmasterol; and back-extracting the extract liquid containing stigmasterol to obtain stigmasterol; wherein the mixed phytosterols comprise stigmasterol and at least one selected from β-sitosterol, campesterol, brassicasterol; the ionic liquid is composed of a choline cation and an anion; and the anion comprises an amino acid anion and / or a carboxylic acid anion.

2. The method of claim 1, wherein, the choline cation comprises a choline cation or a choline cation substituted with one or more substituents selected from alkyl, alkenyl, cyano, thiocyanato, sulfone, carbonyl; the alkyl is preferably a C1-C4 linear or branched alkyl, more preferably a C2-C4 linear alkyl, and the alkenyl is preferably a C2-C4 alkenyl; and / or the amino acid anion is selected from one or more of a neutral amino acid anion, a basic amino acid anion, and an acidic amino acid anion; preferably, the neutral amino acid anion is selected from one or more of a glycine anion, a proline anion, an alanine anion, a leucine anion, a valine anion, and a phenylalanine anion; preferably, the basic amino acid anion is selected from one or more of a tryptophan anion, an asparagine anion, a glutamine anion, a lysine anion, and an arginine anion; and preferably, the acidic amino acid anion is selected from one or more of a cysteine anion, a methionine anion, and a glutamic acid anion; the amino acid anion is optionally substituted with one or more substituents selected from a hydroxyl group, a C1-C4 linear or branched alkyl group, and a C1-C4 linear or branched alkenyl group; and / or the carboxylic acid anion is a C2-C22 saturated or unsaturated carboxylic acid anion, preferably a C8-C22 saturated or unsaturated carboxylic acid anion, more preferably one or more of a n-octanoate anion, a n-decanoate anion, an undecanoate anion, a dodecanoate anion, a myristate anion, a palmitate anion, a laurate anion, a stearate anion, an oleate anion, and a linoleate anion; and further preferably one or more of a n-decanoate anion, a myristate anion, and a palmitate anion.

3. The method according to claim 1 or 2, characterized in that, the extractant is an ionic liquid or a mixture of an ionic liquid and a polar solvent; preferably, in the mixture of the ionic liquid and the polar solvent, the molar percentage content of the ionic liquid is 0.01%-50%, preferably 0.05%-40%, more preferably 0.1%-30%, and further preferably 0.2%-15%; and Preferably, in the mixture of the ionic liquid and the polar solvent, the polar solvent is selected from one or more of water, oxygen-containing organic solvents, phosphorus-containing organic solvents, nitrogen-containing organic solvents, and sulfur-containing organic solvents; more preferably, the polar solvent is selected from one or more of water, alcohols, nitriles, amides, sulfones, and sulfoxides; further preferably, the polar solvent is at least one of water, methanol, ethylene glycol, 1,3-propanediol, glycerol, dimethyl sulfoxide, sulfolane, acetonitrile, N-methyl pyrrolidone, N-methyl formamide, and N,N-dimethyl formamide.

4. The method according to any one of claims 1-3, characterized in that, The ionic liquid is selected from one or more of choline n-decanoate, choline myristate, choline palmitate, choline glycinate, and choline lysinate; and / or The extractant is selected from one or more of choline n-decanoate, choline myristate, choline palmitate, choline glycinate, choline lysinate, a mixture of choline n-decanoate and dimethyl sulfoxide, a mixture of choline myristate and dimethyl sulfoxide, a mixture of choline palmitate and dimethyl sulfoxide, a mixture of choline glycinate and dimethyl sulfoxide, a mixture of choline lysinate and dimethyl sulfoxide, and a mixture of choline n-decanoate and N,N-dimethyl formamide.

5. The method according to any one of claims 1 to 4, characterized in that, The raw material solution further contains a raw material solvent, which includes a non-polar organic solvent and optionally a polar modifier; Preferably, the non-polar organic solvent includes one or more of C6-C12 linear alkanes, C6-C12 branched alkanes, C6-C12 cyclic alkanes, and C1-C6 halogenated alkanes; more preferably, the non-polar organic solvent includes one or more of n-hexane, n-heptane, n-octane, n-nonane, n-decane, 2,2,4-trimethylpentane, isooctane, isodecane, cyclohexane, and methylcyclohexane; further preferably, the non-polar organic solvent is n-hexane; Preferably, the polar modifier includes an alcohol organic solvent; preferably, the polar modifier includes one or more of C1-C4 monohydric alcohols and C2-C4 polyhydric alcohols; more preferably, the polar modifier includes one or more of methanol, ethanol, ethylene glycol, 1,3-propanediol, and glycerol; further preferably, the polar modifier is methanol; More preferably, the volume fraction of the polar modifier is 0.1% to 10%, and more preferably 0.5% to 5%, based on 100% of the total volume of the non-polar organic solvent and the polar modifier.

6. The method according to any one of claims 1-5, characterized in that, In the mixed phytosterols, the content of stigmasterol is 10wt% to 40wt%, and preferably 20wt% to 30wt%; and / or In the raw material solution, the total concentration of phytosterols is 1.0g / L to 100.0g / L, and preferably 5.0g / L to 50.0g / L; and / or The mixed phytosterols include stigmasterol, β-sitosterol, campesterol, and optionally brassicasterol.

7. The method according to any one of claims 1 to 6, characterized in that, In the fractional extraction, the flow ratio of the extractant to the raw material solution is (5 to 25):1, preferably (10 to 25):1, and more preferably (15 to 20):1; and / or In the fractional extraction, the flow ratio of the washing agent to the raw material liquid is (0.1-10):1, preferably (0.5-8):1, and more preferably (1-5):1; and / or The washing agent is the same type as the raw material solvent in the raw material liquid.

8. The method according to any one of claims 1 to 7, characterized in that, The fractional extraction is a multi-stage fractional extraction; preferably, the extraction stage of the multi-stage fractional extraction is 15-50 stages, preferably 15-35 stages, and more preferably 20-30 stages, and the washing stage of the multi-stage fractional extraction is 25-60 stages, and more preferably 30-45 stages; and / or The operation temperature of the fractional extraction is 10-70°C, and preferably 20-50°C.

9. The method according to any one of claims 1-8, characterized in that, The stripping solvent used in the stripping is the same type as the raw material solvent in the raw material liquid.

10. The method according to any one of claims 1-9, characterized in that, The method further comprises: performing vacuum concentration on the stripping phase obtained after the stripping to obtain stigmasterol.

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