Process for the preparation of a composition of methyl linoleate and methyl alpha-linolenate

Abstract

The application relates to the technical field of unsaturated fatty acid and its derivative preparation, in particular to a preparation method of a linoleic acid methyl ester and alpha-linolenic acid methyl ester composition. The preparation method is characterized in that supercritical fluid such as CO2 with strong permeability and high solubility is used for supercritical extraction of soybeans, and an auxiliary solvent such as ethanol is added, so that the oil in the soybeans can be efficiently extracted, and unsaturated fatty acids such as linoleic acid and alpha-linolenic acid can be effectively enriched. The first product is subjected to methyl esterification modification, purified in a simulated moving bed chromatograph, and matched with a C18 fixed phase and a polar eluent, and a port is periodically switched, so that the mass ratio of linoleic acid methyl ester and alpha-linolenic acid methyl ester can be effectively controlled, a feasible way for preparing LA / ALA with a specific mass ratio is provided, and the application requirements can be met.

Description

Technical Field

[0001] This application relates to the field of preparation technology of unsaturated fatty acids and their derivatives, and in particular to a method for preparing a composition of methyl linoleate and methyl α-linolenic acid. Background Technology

[0002] Linoleic acid (LA, ω-6) and alpha-linolenic acid (ALA, ω-3) are two essential polyunsaturated fatty acids that cannot be synthesized in the body and must be obtained through diet. LA and ALA compete with each other in metabolism, sharing desaturase and elongation enzyme systems to convert them into longer-chain unsaturated fatty acids. Excessive intake of one can inhibit the metabolic efficiency of the other. Therefore, maintaining an appropriate LA / ALA intake ratio is crucial for health.

[0003] However, modern diets generally exhibit an imbalance in the LA / ALA ratio, with LA intake being high and ALA intake relatively low. The LA / ALA ratio can reach 20:1 or even higher. This excessively high LA / ALA ratio is closely associated with chronic low-grade inflammation and increases the risk of chronic metabolic diseases such as heart disease, diabetes, obesity, and non-alcoholic fatty liver disease. Appropriately reducing the LA / ALA ratio helps suppress chronic inflammatory responses and promote cardiovascular and brain health. In food additives and related nutritional formulations, the LA to ALA ratio is typically required to be within the range of 1:1 to 15:1, with 1:1 to 8:1 being more ideal.

[0004] There are methods to enrich unsaturated fatty acids using urea inclusion complex technology. Under specific conditions, urea molecules can form crystalline inclusion complexes with straight-chain saturated fatty acids or monounsaturated fatty acids, separating them from the mixed fatty acids. The liquid phase without inclusion complexes is relatively enriched with unsaturated fatty acids (PUFAs). Theoretically, because ALA has more double bonds and a greater degree of carbon chain curvature, its ability to be included by urea is weaker than that of LA. Therefore, LA is more likely to enter the urea inclusion phase, while ALA tends to remain in the liquid phase, thus achieving initial separation between the two. However, this technology has significant limitations in practical applications. First, the difference between LA and ALA in urea inclusion behavior is very small, and the selectivity coefficient between them is extremely low, making separation difficult. Second, the urea inclusion process is affected by various factors such as temperature, solvent composition, urea concentration, and crystallization rate, making process control difficult and reproducibility poor. More importantly, although this method can coarsely separate PUFAs from saturated and monounsaturated fatty acids as a whole, achieving PUFA enrichment, it cannot control the mass ratio of LA to ALA.

[0005] One method uses molecular distillation to separate free fatty acids from crude palm oil with high free fatty acid content. After molecular distillation, the free fatty acid content decreased from 8.7±0.3% to 0.9±0.1%. However, this process only achieves preliminary purification of crude palm oil and does not change the mass ratio of LA to ALA in crude palm oil.

[0006] In summary, traditional methods are insufficient for effectively controlling the mass ratio of LA to ALA. Summary of the Invention

[0007] Based on this, the main objective of this application is to provide a method for preparing a composition of methyl linoleate and methyl alpha-linolenic acid, which can effectively control the mass ratio of methyl linoleate and methyl alpha-linolenic acid, providing a feasible way to prepare LA / ALA with a specific mass ratio and meeting application requirements.

[0008] In a first aspect, this application provides a method for preparing a composition of methyl linoleate and methyl α-linolenic acid, comprising the following steps:

[0009] Soybeans are subjected to supercritical extraction using a supercritical fluid and a co-solvent. The first extract is collected, and the co-solvent is removed from the first extract to prepare a first product. The supercritical fluid includes CO2, and the co-solvent includes ethanol.

[0010] The first product was modified by methyl esterification to prepare the second product;

[0011] The second product was diluted with a first alcohol solvent and used as a raw material solution. The eluent and the raw material solution were passed into a simulated moving bed chromatograph to purify the raw material solution and prepare a composition of methyl linoleate and methyl α-linolenic acid.

[0012] The simulated moving bed chromatography includes a chromatographic zone; the chromatographic zone includes a loop system formed by chromatographic columns connected in series; wherein, according to the eluent flow direction, the loop system is provided with an eluent inlet, an extract outlet, a feed liquid inlet, and a raffinate outlet in sequence, and the chromatographic zone is divided into zone I, zone II, and zone III;

[0013] n1 chromatographic columns are provided between the eluent inlet and the extract outlet to form the I region;

[0014] n2 chromatographic columns are provided between the extract outlet and the feed inlet to form the II zone;

[0015] n3 chromatographic columns are provided between the feed liquid inlet and the raffinate outlet to form the III zone;

[0016] Among them, n1, n2 and n3 are each independently greater than or equal to 1;

[0017] At every time interval t, the eluent inlet, the extract outlet, the feed liquid inlet, and the raffinate outlet simultaneously move one column position along the eluent flow direction, where t is 400s~450s;

[0018] The packing material of the chromatographic column independently includes at least one of C18 hydrophilic silica packing and C18 silica packing;

[0019] The eluent includes a second alcohol solvent.

[0020] In some embodiments, the preparation method satisfies one or more of the following characteristics:

[0021] (1) n1, n2 and n3 are each 1 to 4 independently; optionally, n1 is 2, n2 is 3 and n3 is 3;

[0022] (2) t is 410s~450s.

[0023] In some embodiments, the first alcohol solvent and the second alcohol solvent each independently comprise methanol.

[0024] In some embodiments, the flow rate of the eluent is 3 mL / min-7 mL / min, and optionally 4 mL / min-6 mL / min.

[0025] In some embodiments, the average particle size of the packing material of the chromatographic column is 50 μm to 100 μm.

[0026] In some embodiments, the preparation method includes one or more of the following features:

[0027] (1) The flow rate of the raw material liquid is 0.1 mL / min-1.5 mL / min;

[0028] (2) The flow rate of the extract is 1 mL / min-6 mL / min;

[0029] (3) The flow rate of the raffinate is 0.5 mL / min - 3 mL / min;

[0030] (4) The chromatographic region also includes the IV region; n4 chromatographic columns are provided between the raffinate outlet and the eluent inlet to form the IV region; wherein, n4 is greater than or equal to 1, and optionally, n4 is 1 to 4;

[0031] (5) The purification time is 3h~6h.

[0032] In some embodiments, the conditions for supercritical extraction include one or more of the following characteristics:

[0033] (3) The temperature for supercritical extraction is 30℃~60℃;

[0034] (4) The pressure for supercritical extraction is 15 MPa to 35 MPa;

[0035] (3) The flow rate of the supercritical fluid is 5 L / h to 20 L / h;

[0036] (4) The flow rate of the co-solvent is 5 mL / min to 30 mL / min.

[0037] In some embodiments, the conditions for methyl esterification modification include: mixing the first product with a methanol solution of sodium hydroxide and reacting at 25°C to 45°C for 0.5 h to 2.0 h;

[0038] Optionally, the concentration of sodium hydroxide in the methanol solution of sodium hydroxide is 0.1M to 1M;

[0039] Optionally, the volume ratio of the first product to the methanol solution of sodium hydroxide is 1:(4~10).

[0040] In some embodiments, the volume-to-mass ratio of the second product to the first alcohol solvent is 1 g: (3~8) mL.

[0041] In some embodiments, the mass ratio of methyl linoleate to methyl α-linolenic acid in the methyl linoleate and methyl α-linolenic acid composition is 1:1 to 15:1, and optionally 1:1 to 8:1.

[0042] The beneficial effects of this application are as follows:

[0043] This application employs supercritical fluids such as CO2, which have both strong permeability and high solubility, to perform supercritical extraction on soybeans. At the same time, ethanol and other co-solvents are added to efficiently extract oil from soybeans and effectively enrich unsaturated fatty acids such as linoleic acid and α-linolenic acid. By modifying the first product with methyl esterification and purifying it in simulated moving bed chromatography, and using a C18 stationary phase (C18 hydrophilic silica packing and C18 silica packing) and a polar eluent (a second alcohol solvent, such as methanol), as well as periodically switching ports, on the one hand, methyl esterification converts the strongly polar free fatty acid into a more hydrophobic fatty acid methyl ester, enabling it to have a stable and significant interaction with the nonpolar C18 stationary phase; on the other hand, the presence of the polar eluent forces the methyl linoleate, methyl α-linolenic acid, and other fatty acid methyl esters with different hydrophobicities to be differentiated between the stationary phase and the eluent, achieving efficient separation of methyl linoleate and methyl α-linolenic acid. Furthermore, by adjusting the port switching time, the apparent migration rate of fatty acid methyl esters on the chromatographic column can be adjusted, achieving effective control of the mass ratio of methyl linoleate to methyl α-linolenic acid. Furthermore, methyl linoleate and methyl α-linolenic acid, as esterified derivatives of LA and ALA, can be prepared into the corresponding LA and ALA through hydrolysis. Therefore, the preparation method of the methyl linoleate and methyl α-linolenic acid composition provided in this application can effectively control the mass ratio of methyl linoleate and methyl α-linolenic acid, providing a feasible route for preparing LA / ALA with a specific mass ratio, which can meet application requirements. Moreover, the preparation method of this application is green and environmentally friendly, which helps reduce production costs and is suitable for industrial production. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings are only for illustrating preferred embodiments and are not intended to limit this application. Throughout the drawings, the same reference numerals denote the same parts. In the drawings:

[0045] Figure 1 This is a schematic diagram illustrating the mechanism of action of simulated moving bed chromatography in some embodiments of this application.

[0046] Figure 2 This is a schematic diagram of the supercritical extraction route in some embodiments of this application.

[0047] Figure 3 This is a schematic diagram of the chromatographic region of a simulated moving bed chromatography in some embodiments of this application.

[0048] Figure 4 This is a schematic diagram of port switching for simulated moving bed chromatography in some embodiments of this application.

[0049] Figure 5 This is a schematic diagram of port switching for simulated moving bed chromatography in some embodiments of this application.

[0050] Figure 6 This is a schematic diagram of port switching for simulated moving bed chromatography in some embodiments of this application.

[0051] Figure 7 This is a schematic diagram of port switching for simulated moving bed chromatography in some embodiments of this application.

[0052] Figure 8 This is a schematic diagram of port switching for simulated moving bed chromatography in some embodiments of this application.

[0053] Figure 9 This is a schematic diagram of port switching for simulated moving bed chromatography in some embodiments of this application.

[0054] Figure 10 This is a schematic diagram of port switching for simulated moving bed chromatography in some embodiments of this application.

[0055] Figure 11 This is the GC spectrum of the second product in Example 1.

[0056] Figure 12 This is the GC spectrum of the extract from Example 1.

[0057] Figure 13 This is the GC spectrum of the raffinate from Example 1.

[0058] Figure 14 This is the GC spectrum of the extract from Example 2.

[0059] Figure 15 This is the GC spectrum of the raffinate from Example 2.

[0060] Figure 16 This is the GC spectrum of the extract from Example 3.

[0061] Figure 17 This is the GC spectrum of the raffinate from Example 3.

[0062] Figure 18 This is the GC spectrum of the extract from Example 4.

[0063] Figure 19 This is the GC spectrum of the raffinate from Example 4.

[0064] Figure 20 This is the GC spectrum of the extract from Example 5.

[0065] Figure 21 This is the GC spectrum of the raffinate from Example 5.

[0066] Figure 22This is the GC spectrum of the extract from Example 6.

[0067] Figure 23 This is the GC spectrum of the raffinate from Example 6.

[0068] Figure 24 This is the GC spectrum of the extract from Example 7.

[0069] Figure 25 This is the GC spectrum of the raffinate from Example 7.

[0070] Figure 26 This is the GC spectrum of the extract from Example 8.

[0071] Figure 27 This is the GC spectrum of the raffinate from Example 8.

[0072] Figure 28 This is the GC spectrum of the extract from Example 9.

[0073] Figure 29 This is the GC spectrum of the raffinate from Example 9.

[0074] Figure 30 This is the GC spectrum of the extract from Example 10.

[0075] Figure 31 This is the GC spectrum of the raffinate from Example 10.

[0076] Figure 32 This is the GC spectrum of the extract from Example 11.

[0077] Figure 33 This is the GC spectrum of the raffinate from Example 11.

[0078] Figure 34 This is the GC spectrum of the extract from Example 12.

[0079] Figure 35 This is the GC spectrum of the raffinate from Example 12.

[0080] Figure 36 This is the GC spectrum of the extract from Example 13.

[0081] Figure 37 This is the GC spectrum of the raffinate from Example 13.

[0082] Figure 38 This is the GC spectrum of the extract from Example 14.

[0083] Figure 39 This is the GC spectrum of the raffinate from Example 14.

[0084] Figure 40 This is the GC spectrum of the purified feed solution in Comparative Example 1.

[0085] Figure 41 This is the GC spectrum of the purified feed solution in Comparative Example 2.

[0086] Explanation of reference numerals in the attached figures:

[0087] 1. Eluent inlet; 2. Feed liquid inlet; 3. Extract outlet; 4. Raffinate outlet. Detailed Implementation

[0088] The present application will be further described in detail below with reference to specific embodiments. The present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0089] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this application and in its specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0090] In this application, "one or more" means any one, two or more of the listed items.

[0091] In this application, terms such as "first aspect" and "second aspect" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, terms such as "first" and "second" serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on quantity.

[0092] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0093] In this application, numerical ranges are involved. Unless otherwise specified, the numerical ranges mentioned above are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. In addition, when multiple ranges are provided to describe features or characteristics, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed in this application should be understood to include any and all subranges to which they are included.

[0094] Unless otherwise specified, the percentage content mentioned in this application refers to mass percentage for solid-liquid mixtures and liquid-liquid mixtures, and volume (molar) percentage for gas-gas mixtures.

[0095] Unless otherwise specified, all percentage concentrations mentioned in this application refer to the final concentration. The final concentration refers to the proportion of the added component in the system after the addition of that component.

[0096] Unless otherwise specified, the temperature parameters in this application may be either constant temperature processing or processing within a certain temperature range. The constant temperature processing allows for temperature fluctuations within the precision range controlled by the instrument.

[0097] In this application, unless otherwise specified, the temperature for each operation refers to room temperature. Specifically, room temperature refers to 0~40℃, which can be selected as 20℃~30℃, for example 25±2℃.

[0098] Studies have found that maintaining an appropriate LA / ALA intake ratio is crucial for health, but traditional methods are insufficient to obtain a pure mixture of LA and ALA and to effectively regulate the mass ratio of LA to ALA.

[0099] In view of this, this application provides a method for preparing a composition of methyl linoleate and methyl alpha-linolenic acid, which can effectively control the mass ratio of methyl linoleate and methyl alpha-linolenic acid, providing a feasible way to provide LA / ALA with a specific mass ratio, which can meet application requirements.

[0100] In a first aspect, some embodiments of this application provide a method for preparing a composition of methyl linoleate and methyl α-linolenic acid, comprising the following steps:

[0101] Soybeans are subjected to supercritical extraction using a supercritical fluid and a co-solvent. The first extract is collected, and the co-solvent is removed from the first extract to prepare a first product. The supercritical fluid includes CO2, and the co-solvent includes ethanol.

[0102] The first product was modified by methyl esterification to prepare the second product;

[0103] The second product was diluted with a first alcohol solvent and used as a raw material solution. The eluent and the raw material solution were passed into a simulated moving bed chromatograph to purify the raw material solution and prepare a composition of methyl linoleate and methyl α-linolenic acid.

[0104] The simulated moving bed chromatography includes a chromatographic zone; the chromatographic zone includes a loop system formed by chromatographic columns connected in series; wherein, according to the eluent flow direction, the loop system is provided with an eluent inlet, an extract outlet, a feed liquid inlet, and a raffinate outlet in sequence, and the chromatographic zone is divided into zone I, zone II, and zone III;

[0105] n1 chromatographic columns are provided between the eluent inlet and the extract outlet to form the I region;

[0106] n2 chromatographic columns are provided between the extract outlet and the feed inlet to form the II zone;

[0107] n3 chromatographic columns are provided between the feed liquid inlet and the raffinate outlet to form the III zone;

[0108] Among them, n1, n2 and n3 are each independently greater than or equal to 1;

[0109] At every time interval t, the eluent inlet, the extract outlet, the feed liquid inlet, and the raffinate outlet simultaneously move one column position along the eluent flow direction, where t is 400s~450s;

[0110] The packing material of the chromatographic column independently includes at least one of C18 hydrophilic silica packing and C18 silica packing;

[0111] The eluent includes a second alcohol solvent.

[0112] This application employs supercritical fluids such as CO2, which have both strong permeability and high solubility, to perform supercritical extraction on soybeans. At the same time, ethanol and other co-solvents are added to efficiently extract oil from soybeans and effectively enrich unsaturated fatty acids such as linoleic acid and α-linolenic acid. By modifying the first product with methyl esterification and purifying it in simulated moving bed chromatography (SMB), and using a C18 stationary phase (C18 hydrophilic silica packing and C18 silica packing) and a polar eluent (a second alcohol solvent, such as methanol), as well as periodically switching ports, on the one hand, methyl esterification converts the strongly polar free fatty acid into a more hydrophobic fatty acid methyl ester, enabling it to have a stable and significant interaction with the nonpolar C18 stationary phase; on the other hand, the presence of the polar eluent forces the methyl linoleate, methyl α-linolenic acid, and other fatty acid methyl esters with different hydrophobicities to be differentiated between the stationary phase and the eluent, achieving efficient separation of methyl linoleate and methyl α-linolenic acid. Furthermore, by adjusting the port switching time, the apparent migration rate of fatty acid methyl esters on the chromatographic column can be adjusted, achieving effective control of the mass ratio of methyl linoleate to methyl α-linolenic acid. Furthermore, methyl linoleate and methyl α-linolenic acid, as esterified derivatives of LA and ALA, can be prepared into the corresponding LA and ALA through hydrolysis. Therefore, the preparation method of the methyl linoleate and methyl α-linolenic acid composition provided in this application can effectively control the mass ratio of methyl linoleate and methyl α-linolenic acid, providing a feasible route for preparing LA / ALA with a specific mass ratio, which can meet application requirements. Moreover, the preparation method of this application is green and environmentally friendly, which helps reduce production costs and is suitable for industrial production.

[0113] In some embodiments, n1, n2 and n3 are each independently 1 to 4, for example 1, 2, 3 or 4; optionally, n1 is 2, n2 is 3 and n3 is 3.

[0114] Understandably, the simultaneous movement of the eluent inlet, extractant outlet, feed inlet, and raffinate outlet along the eluent flow direction by one column position means that these four locations move relative to the column along the eluent flow direction by one column position. Here, "movement" refers to "relative movement." In reality, the column itself remains stationary. Valves are used to periodically move the positions of each inlet and outlet forward by one column position. That is, every time interval t, the system moves the eluent inlet, extractant outlet, feed inlet, and raffinate outlet (i.e., all inlets and outlets) simultaneously along the eluent flow direction to the corresponding interface position of the next column, thus functionally achieving continuous countercurrent movement of the stationary phase relative to the liquid mobile phase.

[0115] In some embodiments, t can be selected from 410s to 450s, specifically 400s, 410s, 415s, 420s, 425s, 430s, 435s, 440s, 445s, and 450s. Understandably, controlling the port switching time t within the above range facilitates sufficient flow of the feed solution in zones I, II, and III, allowing it to fully interact with the chromatographic column packing material. Simultaneously, it increases the apparent migration rate difference between methyl linoleate, methyl α-linolenic acid, and other fatty acid methyl esters, which is beneficial for the effective separation of methyl linoleate and methyl α-linolenic acid, improving the purity of methyl linoleate and methyl α-linolenic acid in the composition. Furthermore, it enables effective control of the mass ratio of methyl linoleate to methyl α-linolenic acid, resulting in a high-purity composition of methyl linoleate and methyl α-linolenic acid with a specific mass ratio.

[0116] In some embodiments, the first alcohol solvent and the second alcohol solvent each independently comprise methanol.

[0117] In some embodiments, the flow rate of the eluent is 3 mL / min-7 mL / min, and can be selected as 4 mL / min-6 mL / min, such as 3 mL / min, 4 mL / min, 4.5 mL / min, 5 mL / min, 5.5 mL / min, 6 mL / min, 7 mL / min, etc.

[0118] Understandably, controlling the eluent flow rate within an appropriate range is beneficial in two ways. First, it allows the feed solution to flow sufficiently in zones I, II, and III, interacting fully with the column packing material and improving resolution. Second, it increases the apparent migration rate difference between methyl linoleate, methyl α-linolenic acid, and other fatty acid methyl esters, enabling effective separation of methyl linoleate and methyl α-linolenic acid, thus improving the purity of methyl linoleate and methyl α-linolenic acid in the composition, and simultaneously allowing for effective control of the mass ratio of methyl linoleate to methyl α-linolenic acid. This results in a high-purity composition of methyl linoleate and methyl α-linolenic acid with a specific mass ratio.

[0119] In some embodiments, the average particle size of the packing material of the chromatographic column is 50 μm to 100 μm, such as 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, etc. It is understood that controlling the average particle size of the packing material within the above range is beneficial for balancing purification and separation effects with process costs.

[0120] In some embodiments, the column size of the chromatographic column is (5~20) mmID × (50~200) mmL, for example, 10 mmID × 100 mmL.

[0121] In some embodiments, the pore size of the packing material of the chromatographic column is 100 Å to 500 Å, and the specific surface area is 100 m². 2 / g~500m 2 / g.

[0122] In some embodiments, the flow rate of the feed liquid is 0.01 mL / min to 1 mL / min, for example, 0.01 mL / min, 0.05 mL / min, 0.1 mL / min, 0.2 mL / min, 0.4 mL / min, 0.6 mL / min, 0.8 mL / min, 1 mL / min, etc.

[0123] In some embodiments, the flow rate of the extract is 1 mL / min to 6 mL / min, for example, 1 mL / min, 2 mL / min, 3 mL / min, 4 mL / min, 5 mL / min, 6 mL / min, etc.

[0124] In some embodiments, the flow rate of the raffinate is 0.5 mL / min to 3 mL / min, for example, 0.5 mL / min, 1 mL / min, 1.5 mL / min, 2 mL / min, 2.5 mL / min, 3 mL / min, etc.

[0125] In some embodiments, the chromatographic region further includes a region IV; n4 chromatographic columns are provided between the raffinate outlet and the eluent inlet to form the region IV; wherein n4 is greater than or equal to 1, and optionally, n4 is 1 to 4, for example 1, 2, 3 or 4.

[0126] like Figure 1 As shown, the chromatographic region includes a loop system formed by chromatographic columns connected in series. The loop system is sequentially equipped with an eluent inlet, an extract outlet, a feed inlet, and a raffinate outlet, following the eluent flow direction. The chromatographic region is divided into zones I, II, III, and an optional zone IV. Zone I is formed by n1 chromatographic columns between the eluent inlet and the extract outlet; Zone II is formed by n2 chromatographic columns between the extract outlet and the feed inlet; Zone III is formed by n3 chromatographic columns between the feed inlet and the raffinate outlet; and Zone IV is formed by n4 chromatographic columns between the raffinate outlet and the eluent inlet. During operation, the four inlet and outlet positions periodically switch to the next column along the eluent flow direction, causing the stationary phase to move in a "simulated" countercurrent relative to the eluent at each inlet and outlet position. This "simulated" countercurrent effect increases the mass transfer driving force between the stationary phase and the eluent, fully utilizing the stationary phase and fundamentally improving separation efficiency. Compared to fixed adsorption beds, simulated moving bed chromatography can significantly improve production capacity and separation efficiency. At the same time, it fundamentally solves the problems of wear, clogging and particle channeling caused by adsorbent movement in traditional moving bed processes, thus ensuring the long-term stable operation of the system.

[0127] In some embodiments, the purification time is 3h to 6h, for example 3h, 4h, 5h, 6h, etc.

[0128] In some embodiments, the supercritical extraction temperature is 30°C to 60°C, such as 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, etc.

[0129] In some embodiments, the supercritical extraction pressure is 10 MPa to 40 MPa, such as 10 MPa, 15 MPa, 20 MPa, 25 MPa, 30 MPa, 35 MPa, 40 MPa, etc.

[0130] In some embodiments, the flow rate of the supercritical fluid is 5 L / h to 20 L / h, such as 5 L / h, 10 L / h, 15 L / h, 20 L / h, etc.

[0131] In some embodiments, the flow rate of the co-solvent is 5 mL / min to 30 mL / min, for example, 5 mL / min, 10 mL / min, 15 mL / min, 20 mL / min, 25 mL / min, 30 mL / min, etc.

[0132] In some embodiments, the conditions for methyl esterification modification include: mixing the first product with a methanol solution of sodium hydroxide and reacting it at 25°C to 45°C (e.g., 25°C, 30°C, 35°C, 40°C, 45°C, etc.) for 0.5h to 2.5h (e.g., 0.5h, 1h, 1.5h, 2h, 2.5h, etc.).

[0133] In some embodiments, the concentration of sodium hydroxide in the methanol solution of sodium hydroxide is 0.1M to 1M, for example, 0.1M, 0.2M, 0.4M, 0.6M, 0.8M, 1M, etc.

[0134] In some embodiments, the volume ratio of the first product to the methanol solution of sodium hydroxide is 1:(4~10), for example 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, etc.

[0135] In some embodiments, the methyl esterification modification is carried out in the presence of an organic solvent; optionally, the organic solvent includes n-hexane; optionally, the volume ratio of the first product to the organic solvent is 1:(1~3), for example 1:1, 1:1.5, 1:2, 1:2.5, 1:3, etc.

[0136] In some embodiments, the volume-to-mass ratio of the second product to the first alcohol solvent is 1g:(3~8)mL, for example 1g:3mL, 1g:4mL, 1g:5mL, 1g:6mL, 1g:7mL, 1g:8mL, etc.

[0137] In some embodiments, the mass ratio of methyl linoleate to methyl α-linolenic acid in the methyl linoleate and methyl α-linolenic acid composition is 1:1 to 15:1, and can be selected as 1:1 to 8:1, such as 1:1, 2:1, 4:1, 6:1, 8:1, 10:1, 12:1, 14:1, 15:1, etc.

[0138] For experimental parameters not specified in the following specific embodiments, please refer to the guidelines given in this application document first, or refer to experimental manuals or other experimental methods known in the art, or refer to the experimental conditions recommended by the manufacturer.

[0139] Example 1

[0140] Preparation method of the composition of methyl linoleate and methyl α-linolenic acid:

[0141] 1) Supercritical extraction: Weigh 10 kg of fresh soybeans, wash and dry them, then grind them using a high-speed blender. Dry the soybean powder in an oven at 45℃ for 24 hours to obtain uniformly dried soybean powder. The supercritical equipment flow chart is shown below. Figure 2As shown, soybean powder is loaded into the extraction tank of the supercritical extraction equipment. The cooling system is turned on, and the temperature of the CO2 storage tank is set to -5℃. The constant-temperature hot water circulation system is turned on, and the temperature of the extraction tank is set to 50℃. Once ready, carbon dioxide is introduced into the CO2 storage tank of the extraction system, causing the CO2 to become liquid. The CO2 pump is started, and the pump flow rate is set to 10 L / h. After three venting operations to remove air from the system, the CO2 is pumped into the extraction tank, while simultaneously pumping in the co-solvent ethanol at a flow rate of 15 mL / min. The pressure valve (pressure valve 1) at the rear of the extraction tank is adjusted to make the pressure in the extraction tank 20 MPa, and the CO2 in the extraction tank becomes supercritical. The supercritical CO2 and the extraction product enter two collection tanks (collection tank 1 and collection tank 2) after the extraction tank for two rounds of collection. The pressure valve (pressure valve 2) of collection tank 1 is adjusted to make the pressure in collection tank 1 5 MPa, and the CO2 becomes gas in collection tank 1 and enters the recooling system for recycling. The first extract (containing soybean oil and a small amount of co-solvent ethanol) is stored in collection tank 1. The first extract is then subjected to rotary evaporation under reduced pressure at 35°C to remove the ethanol, yielding the first product (soybean oil), which is then stored in a -4°C refrigerator.

[0142] 2) Methyl esterification modification: Take 3 mL of the first product and place it in a 50 mL glass beaker. Add 5 mL of n-hexane and stir to dissolve, obtaining a mixture. Prepare a 0.5 M NaOH-methanol solution (4 g / 200 mL). Add 20 mL of the 0.5 M NaOH-methanol solution (excess) to the mixture and heat in a 35 °C water bath for 1 h. After the reaction is complete, extract the fatty acid methyl ester with n-hexane. Wash the upper organic phase three times with water, then once with saturated sodium chloride solution, and dry with anhydrous magnesium sulfate. Filter and remove n-hexane by rotary evaporation under reduced pressure at 35 °C to obtain the second product.

[0143] 3) Simulated moving bed chromatography purification: Weigh 200g of the second product at room temperature, add anhydrous methanol to a final volume of 1L at 23℃, stir well, filter using a 0.22μm PES filter membrane, and collect the filtrate to obtain a completely clear feed solution.

[0144] The structure of simulated moving bed chromatography (SMB) is as follows: Figure 3 As shown, the simulated moving bed chromatography includes a chromatographic zone containing eight columns (C1-C8) of the same model and internal packing material, using 50μm C18 hydrophilic silica packing material (Unisil). ®C18 50-120 AQ (purchased from Suzhou Nanomicro Technology Co., Ltd.) is used as the packing material. The column size is 10mm Id × 100mm L, and the columns are connected in series to form a loop system. The loop system is equipped with eluent inlet 1, feed inlet 2, extract outlet 3, and raffinate outlet 4 in sequence. The chromatographic zone is divided into zone I, zone II, and zone III. Zone I has 2 columns C1~C2, zone II has 3 columns C3~C5, and zone III has 3 columns C6~C8. Eluent inlet 1, feed inlet 2, and extract outlet 3 are respectively connected to pumps 1~3 for flow rate control.

[0145] Turn on the SMB device and the online computer; the device should be in standby mode. Open the SMB control software, set the SMB port switching mode, and adjust the software to bring the device valves to their initial switching state. Turn on pump 1 connected to SMB eluent inlet 1, pump in anhydrous methanol, and run for 15 minutes to remove air bubbles from the system. Set the flow rate of pump 1 at eluent inlet 1 to 4 mL / min, the flow rate of pump 2 at feed liquid inlet 2 to 0.1 mL / min, and the flow rate of pump 3 at extractant outlet 3 to 2.5 mL / min, with a port switching time of 400 s. After running pump 1 for 5 minutes, turn on pump 3 connected to extractant outlet 3 and simultaneously start the SMB valve automatic switching program; the system will then begin pre-running.

[0146] After the SMB equipment has been running for 30 minutes, turn on pump 2 connected to feed inlet 2 to pump in the feed solution. At this point, the flow rate of raffinate outlet 4 is 1.6 mL / min. Continue running according to the pre-set SMB equipment parameters. Every 400 seconds, switch ports according to the liquid flow direction to switch to the next column. This moves the eluent inlet, extract outlet, feed inlet, and raffinate outlet simultaneously along the eluent flow direction by one column position (e.g., eluent inlet 1 switches from C1 to C2, extract outlet 3 switches from C2 to C3, feed inlet 2 switches from C6 to C7, raffinate outlet 4 switches from C8 to C1, and so on). Figures 3 to 10 (As shown). After the SMB device has been running for 4 hours, the extract from extractor outlet 3 and the raffinate from raffinate outlet 4 are collected. 50 mL samples are taken from each sample, and methanol is removed by purging with nitrogen gas to obtain the sample to be analyzed.

[0147] Example 2-14

[0148] Except for differences in eluent flow rate, extractant flow rate, port switching time, or column packing, all other aspects are the same as in Example 1, with the differences shown in Table 1. Specifically, Example 13 uses silica gel packing material (Unisil) with an average particle size of 50 μm. ®C18 50-120 (purchased from Suzhou Nanomicro Technology Co., Ltd.), Example 14 uses 100μm silica gel filler (model Unisil). ® C18 100-120, purchased from Suzhou Nanomicro Technology Co., Ltd.

[0149] Comparative Example 1

[0150] Except for the purification method, the rest is the same as in Example 1. The purification steps are as follows: A chromatographic column was packed with 50 μm C18 hydrophilic silica gel packing material (same as in Example 1), and the column size was 10 mm. ID ×100mm L Anhydrous methanol was used as the eluent at a flow rate of 4 mL / min. After equilibration of the high-performance liquid chromatography (HPLC) system for 40 min, the sample was injected in a volume of 25 mL. The HPLC time program was set to isocratic elution with pure anhydrous methanol, with samples taken every 1 min until all the sample was eluent. The methanol in the sample was removed by purging with nitrogen gas to obtain the sample to be analyzed.

[0151] Comparative Example 2

[0152] Except for the purification method, the rest is the same as in Example 14. The purification steps are as follows: A chromatographic column is packed with 100 μm C18 silica gel packing material (same as in Example 14), and the column size is 10 mm. ID ×100mm L Anhydrous methanol was used as the eluent at a flow rate of 4 mL / min. After equilibration of the high-performance liquid chromatography (HPLC) system for 40 min, the sample was injected in a volume of 25 mL. The HPLC time program was set to isocratic elution with pure anhydrous methanol, with samples taken every 1 min until all the sample was eluent. The methanol in the sample was removed by purging with nitrogen gas to obtain the sample to be analyzed.

[0153] Table 1. Reactor structure and process parameters of the examples and comparative examples

[0154]

[0155] Test case

[0156] The methyl linoleate and methyl α-linolenic acid in the second product before and after purification were detected: 100.0 mg of the second product (Example 1) or the combination of methyl linoleate and methyl α-linolenic acid (Examples and Comparative Examples) were weighed at room temperature and dissolved in 10 mL of methanol. After complete dissolution, the solution was filtered through a 0.22 μm PES membrane, and the filtrate was transferred to a gas chromatograph vial as the sample solution. The sample solution was tested using a gas chromatograph (GC) with a G6825-3002 NanoChrom BP-FAME Wax (30m) column. L ×0.25 mmID (0.25 mm), with N2 as the carrier gas. The positions of the peaks corresponding to fatty acid methyl esters in the gas chromatogram were determined using fatty acid methyl ester standards. The test conditions are shown in Table 2, and the results are shown in Table 3. The GC spectra of the tested samples from front to back according to the order in Table 3 are shown in Table 3. Figures 11-41 .

[0157] Table 2 GC Test Analysis Conditions

[0158]

[0159] Table 3 GC Test Results

[0160]

[0161] The GC spectrum of the unpurified second product is shown below. Figure 11 As shown in Table 3, it contains methyl palmitate, methyl stearate, methyl g-oleate, methyl linoleate and methyl α-linolenic acid. The total content of methyl linoleate and methyl α-linolenic acid is 54.26 wt%, which is relatively low in purity. The mass ratio of methyl linoleate to methyl α-linolenic acid is 10.52:1.

[0162] The GC spectra of the extracts and raffinates from Examples 1-8 are shown in the following figures. Figures 12-27 As shown in Table 3, the port switching time has a significant impact on the mass ratio of methyl linoleate and methyl α-linolenic acid, as well as the purity of methyl linoleate and methyl α-linolenic acid. Controlling the time to 410s~450s is beneficial for obtaining a high-purity composition of methyl linoleate and methyl α-linolenic acid with a mass ratio in the range of 1:1~15:1.

[0163] The GC spectra of the extracts and raffinates from Examples 9-12 are shown in the following figures. Figures 28-35 As can be seen from Example 6, the eluent flow rate has a significant impact on the mass ratio of methyl linoleate and methyl α-linolenic acid, as well as the purity of methyl linoleate and methyl α-linolenic acid. Controlling the eluent flow rate to 4 mL / min to 6 mL / min is beneficial for obtaining a high-purity composition of methyl linoleate and methyl α-linolenic acid with a mass ratio in the range of 1:1 to 15:1.

[0164] The GC spectra of the extracts and raffinates from Examples 13 and 14 are shown in the following figures, respectively. Figures 36-39 It can be seen that controlling the particle size of C18 hydrophilic silica packing or C18 silica packing to 50μm~100μm can achieve good purification results, which is beneficial for obtaining high-purity compositions of methyl linoleate and methyl α-linolenic acid with a mass ratio in the range of 1:1~15:1.

[0165] The GC spectra of the purified solutions from Comparative Examples 1 to 2 are shown in the following figures. Figures 40-41 It can be seen that the traditional isocratic elution single-column chromatography process has almost no regulatory effect on LA / ALA in the second product.

[0166] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0167] The embodiments described above are merely illustrative of several implementation methods of this application, intended to facilitate a detailed understanding of the technical solutions of this application, but should not be construed as limiting the scope of protection of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. It should be understood that technical solutions obtained by those skilled in the art based on the technical solutions provided in this application through logical analysis, reasoning, or limited experimentation are all within the scope of protection of this application.

Claims

1. A method for preparing a composition of methyl linoleate and methyl α-linolenic acid, characterized in that, Includes the following steps: Soybeans are subjected to supercritical extraction using a supercritical fluid and a co-solvent. The first extract is collected, and the co-solvent is removed from the first extract to prepare a first product. The supercritical fluid includes CO2, and the co-solvent includes ethanol. The first product was modified by methyl esterification to prepare the second product; The second product was diluted with a first alcohol solvent and used as a raw material solution. The eluent and the raw material solution were passed into a simulated moving bed chromatograph to purify the raw material solution and prepare a composition of methyl linoleate and methyl α-linolenic acid. The simulated moving bed chromatography includes a chromatographic zone; the chromatographic zone includes a loop system formed by chromatographic columns connected in series; wherein, according to the eluent flow direction, the loop system is provided with an eluent inlet, an extract outlet, a feed liquid inlet, and a raffinate outlet in sequence, and the chromatographic zone is divided into zone I, zone II, and zone III; n1 chromatographic columns are provided between the eluent inlet and the extract outlet to form the I region; n2 chromatographic columns are provided between the extract outlet and the feed inlet to form the II zone; n3 chromatographic columns are provided between the feed liquid inlet and the raffinate outlet to form the III zone; Among them, n1, n2 and n3 are each independently greater than or equal to 1; At every time interval t, the eluent inlet, the extract outlet, the feed liquid inlet, and the raffinate outlet simultaneously move one column position along the eluent flow direction, where t is 400s~450s; The packing material of the chromatographic column independently includes at least one of C18 hydrophilic silica packing and C18 silica packing; The eluent includes a second alcohol solvent.

2. The preparation method according to claim 1, characterized in that, The preparation method satisfies one or more of the following characteristics: (1) n1, n2 and n3 are each 1 to 4 independently; optionally, n1 is 2, n2 is 3 and n3 is 3; (2) t is 410s~450s.

3. The preparation method according to claim 1, characterized in that, The first alcohol solvent and the second alcohol solvent each independently include methanol.

4. The preparation method according to claim 1, characterized in that, The flow rate of the eluent is 3 mL / min-7 mL / min, and can be selected as 4 mL / min-6 mL / min.

5. The preparation method according to any one of claims 1 to 4, characterized in that, The average particle size of the packing material for the chromatographic column is 50 μm to 100 μm.

6. The preparation method according to any one of claims 1 to 4, characterized in that, The preparation method includes one or more of the following features: (1) The flow rate of the raw material liquid is 0.1 mL / min-1.5 mL / min; (2) The flow rate of the extract is 1 mL / min-6 mL / min; (3) The flow rate of the raffinate is 0.5 mL / min - 3 mL / min; (4) The chromatographic region also includes region IV; n4 chromatographic columns are provided between the raffinate outlet and the eluent inlet to form region IV; wherein, n4 is greater than or equal to 1, and optionally, n4 is 1 to 4; (5) The purification time is 3h~6h.

7. The preparation method according to any one of claims 1 to 4, characterized in that, The conditions for supercritical fluid extraction include one or more of the following characteristics: (1) The temperature for supercritical extraction is 30℃~60℃; (2) The pressure for supercritical extraction is 15 MPa to 35 MPa; (3) The flow rate of the supercritical fluid is 5 L / h to 20 L / h; (4) The flow rate of the co-solvent is 5 mL / min to 30 mL / min.

8. The preparation method according to any one of claims 1 to 4, characterized in that, The conditions for methyl esterification modification include: mixing the first product with a methanol solution of sodium hydroxide and reacting at 25℃~45℃ for 0.5h~2.0h; Optionally, the concentration of sodium hydroxide in the methanol solution of sodium hydroxide is 0.1M to 1M; Optionally, the volume ratio of the first product to the methanol solution of sodium hydroxide is 1:(4~10).

9. The preparation method according to any one of claims 1 to 4, characterized in that, The volume-to-mass ratio of the second product to the first alcohol solvent is 1 g: (3~8) mL.

10. The preparation method according to any one of claims 1 to 4, characterized in that, In the composition of methyl linoleate and methyl α-linolenic acid, the mass ratio of methyl linoleate to methyl α-linolenic acid is 1:1 to 15:1, and can be selected as 1:1 to 8:1.

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