A method for removing glycidyl esters from mixed tocopherols

Abstract

This application belongs to the technical field of tocopherols and specifically provides a method for removing glycidyl esters from mixed tocopherols, comprising the following steps: 1) pretreating the deodorized vegetable oil distillate, followed by molecular distillation and chromatography to obtain a crude tocopherol product; 2) uniformly mixing the crude tocopherol product with an adsorbent, performing an adsorption treatment, and filtering; the adsorbent is made of a polysaccharide gel and a composite metal-doped material; the composite metal-doped material includes a zinc-doped zirconium skeleton component. This removal method has the advantages of thorough and efficient glycidyl ester removal.

Description

Technical Field

[0001] The present application belongs to the technical field of tocopherols, and in particular relates to a method for removing glycidyl esters in mixed tocopherols. Background Art

[0002] Natural tocopherol is a physiologically active dextrorotatory isoform, resulting in superior biological activity and food safety compared to synthetic tocopherol. It is non-toxic, easily absorbed, and has high nutritional value, leading to its widespread use in medicine, food, cosmetics, and health supplements. Natural sources of natural tocopherol are very limited, and the primary source for industrial production is currently the byproduct (deodorized distillate) of oil processing. However, the complex composition of deodorized distillate makes it difficult to effectively extract high-purity natural tocopherol from it using a single method. Therefore, pretreatment of the raw material is often required before purification of the tocopherol. Currently, the most commonly used pretreatment methods are esterification and saponification, while extraction processes include solvent extraction, supercritical fluid extraction, distillation, adsorption, and ion exchange. In addition, physical assistance methods such as ultrasound, microwave, and magnetic fields are also used.

[0003] The above separation and purification process removes most impurities, such as free fatty acids, from tocopherol products. However, a certain amount of glycidyl esters (GEs) will remain. Toxicological data on the genotoxic and nephrotoxic effects of glycidyl esters has gradually been revealed, and some organizations have established regulations and limits on GE content in health supplements and infant foods. The control and removal of GEs from tocopherols has long been a hot topic and a difficult issue in the industry. Deodorization conditions can be optimized by inhibiting and removing their precursors, controlling the levels of monoglycerides, diglycerides, and chloride ions, and appropriately reducing the deodorization temperature and time. Other methods include enzymatic hydrolysis, two-stage molecular distillation, and adsorption to reduce GE content.

[0004] Among various removal methods, enzymatic hydrolysis carries the risk of hydrolyzing triglycerides due to the involvement of enzymes. In contrast, adsorption methods not only offer advantages such as low investment and energy consumption, but also can absorb harmful components in oils and fats, such as polycyclic aromatic hydrocarbons and plasticizers. For example, patent application publication number CN111233813A discloses a method for removing glycidyl esters from mixed tocopherols. This method utilizes a first-stage strong base ion exchange resin for adsorption, followed by a second-stage strong base ion exchange resin for adsorption, while simultaneously maintaining a low temperature to reduce the formation of glycidyl esters. However, this method is relatively complex and costly.

[0005] Another example is "Study on the Removal of 3-Chloropropanol and Glycidyl Esters in Fish Oil by Biosorbents" - Zhang Fang. The author used biochar-clay as an adsorbent to remove glycidyl esters, but the removal rate and stability are still relatively low for food-grade tocopherol products. Therefore, how to develop a high removal rate method for glycidyl esters in tocopherol is an urgent problem to be solved. Summary of the Invention

[0006] In view of the above problems, in order to further improve the removal rate of glycidyl esters in tocopherols, the present application provides a method for removing glycidyl esters in mixed tocopherols.

[0007] The present application provides a method for removing glycidyl esters in mixed tocopherols, comprising the following steps:

[0008] 1) Pre-treating the deodorized vegetable oil distillate, followed by molecular distillation and chromatography to obtain crude tocopherol;

[0009] 2) Evenly mixing the crude tocopherol and an adsorbent, performing adsorption treatment, and filtering; the adsorbent is made of a polysaccharide gel and a composite metal doping material; the composite metal doping material includes a zinc-doped zirconium skeleton component.

[0010] Furthermore, in the step 1), the pretreatment is to subject the vegetable oil deodorization distillate to esterification treatment;

[0011] And / or, in step 1), the vegetable oil is one of rapeseed oil, soybean oil, corn oil, olive oil, cottonseed oil, sunflower oil, and tea oil;

[0012] And / or, in the step 1), the molecular distillation is performed by first-stage molecular distillation, second-stage molecular distillation and third-stage molecular distillation respectively.

[0013] Furthermore, in step 2), the adsorption treatment is carried out at a temperature of 70-85° C. for 30-45 minutes;

[0014] And / or, in step 2), the polysaccharide gel is one or more of cellulose gel, cyclodextrin gel, and sodium alginate gel;

[0015] And / or, in step 2), the composite metal doping material is composed of a zinc-doped zirconium skeleton component and a calcium-magnesium co-deposited component in a mass ratio of 1:(0.5-0.65).

[0016] Furthermore, the polysaccharide gel is prepared by a method comprising the following steps:

[0017] A) Deionized water, polysaccharide, and 3-aminophenylboronic acid are mixed uniformly, and then aldehyde-terminated polyethylene glycol is added and mixed uniformly to obtain an intermediate solution;

[0018] B) Add polyethyleneimine to the intermediate solution, ultrasonically shake, age and wash to obtain the product.

[0019] Furthermore, in step A), the mass ratio of deionized water, polysaccharide, and 3-aminophenylboronic acid is 1:(0.15-0.2):(0.03-0.05);

[0020] And / or, in step A), the polysaccharide is one or more of cellulose, cyclodextrin, and sodium alginate;

[0021] And / or, in step A), the proportion of the aldehyde-terminated polyethylene glycol in the intermediate solution is 35-60 wt %.

[0022] Furthermore, in step B), the molar ratio of the amino group of the polyethyleneimine to the aldehyde group of the aldehyde-terminated polyethylene glycol in the intermediate solution is 1:(0.8-1);

[0023] And / or, in step B), the Mw of the polyethyleneimine is 400-1500.

[0024] Furthermore, the zinc-doped zirconium framework component is prepared by the following steps: preparing a zinc-zirconium mixed solution, adding glacial acetic acid and 2,6-naphthalene dicarboxylic acid to the zinc-zirconium mixed solution and mixing them evenly, heating for reaction, washing, drying, and calcining to obtain the component.

[0025] Furthermore, the calcium-magnesium co-precipitation component is prepared by the following steps: preparing a calcium-magnesium mixed solution, adding triethylamine to the calcium-magnesium mixed solution, then dropwise adding a sodium carbonate solution, then heating to remove the triethylamine, centrifuging to obtain a precipitate, washing, and drying.

[0026] Furthermore, the adsorbent is prepared by the following steps:

[0027] S1: adding a hydrochloric acid buffer solution to the polysaccharide gel, and then adding a composite metal doping material and mixing uniformly to prepare a mixed solution;

[0028] S2: Add quaternary ammonium solution dropwise to the mixed solution under continuous stirring until it becomes neutral, filter, wash and dry to obtain the product.

[0029] Furthermore, the hydrochloric acid buffer solution includes the following raw materials: deionized water, concentrated hydrochloric acid, sodium chloride, and zinc chloride.

[0030] Compared with the prior art, this application has the following beneficial effects:

[0031] 1. This application adopts a compound system of polysaccharide gel and composite metal doping material. On the one hand, the diffusion and adsorption effect of glycidyl ester on the surface and inside of the adsorbent are improved through the capillary adsorption effect of the polysaccharide gel; on the other hand, the intermolecular conjugation effect produced by the composite metal doping material is enhanced to enhance the enrichment and adsorption effect of glycidyl ester molecules, thereby promoting the adsorption of glycidyl ester.

[0032] 2. The composite metal-doped material of this application incorporates irregular nanoparticles of calcium-magnesium co-deposited components, which can produce interfacial adsorption of glycidyl ester molecules, thereby enhancing the adsorbent's glycidyl ester removal rate. Furthermore, because the polysaccharide gel and the composite metal-doped material exhibit different adsorption rates for glycidyl ester, and the adsorbent has a core composed of the composite metal-doped material and a polysaccharide gel as its shell, this structure can, to a certain extent, mitigate the concentration polarization phenomenon that occurs during glycidyl ester adsorption, thereby achieving a stable and efficient adsorption effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of adsorption stability test data of the adsorbents of Examples 1-3 and Control Groups 1-2 of the present application.

[0034] Figure 2 Schematic diagram of the adsorbent hybrid formation process of Examples 1-3 of the present application.

[0035] Figure 3 This is a schematic diagram of the appearance of the polysaccharide gel and adsorbent of Example 3 of the present application.

[0036] Figure 4 This is a TEM image of the adsorbent of Example 1 of the present application.

[0037] Figure 5 This is a TEM image of the adsorbent of Example 2 of the present application.

[0038] Figure 6 This is a TEM image of the adsorbent of Example 3 of the present application. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0040] After a large number of experimental studies, this application has developed an adsorption system of metal-doped material composite polysaccharide gel based on traditional inorganic adsorption materials such as white clay, activated carbon, attapulgite, nano-silica, bentonite, diatomaceous earth, etc., taking the adsorption characteristics of glycidyl ester molecules as the starting point, which greatly improves the removal rate of glycidyl ester.

[0041] Specifically, the present application provides a method for removing glycidyl esters in mixed tocopherols, comprising the following steps:

[0042] 1) Pre-treating the deodorized vegetable oil distillate, followed by molecular distillation and chromatography to obtain crude tocopherol;

[0043] 2) Evenly mixing the crude tocopherol and an adsorbent, performing adsorption treatment, and filtering; the adsorbent is made of a polysaccharide gel and a composite metal doping material; the composite metal doping material includes a zinc-doped zirconium skeleton component.

[0044] Furthermore, in the step 1), the pretreatment is to subject the vegetable oil deodorization distillate to esterification treatment;

[0045] And / or, in step 1), the vegetable oil is one of rapeseed oil, soybean oil, corn oil, olive oil, cottonseed oil, sunflower oil, and tea oil;

[0046] And / or, in the step 1), the molecular distillation is performed by first-stage molecular distillation, second-stage molecular distillation and third-stage molecular distillation respectively.

[0047] In some specific embodiments, in step 1), the esterification treatment is performed by adding a dehydrating agent and immobilized lipase to the vegetable oil deodorization distillate, mixing them evenly, slowly adding methanol to carry out esterification reaction to obtain an esterified liquid, filtering to recover the dehydrating agent and immobilized lipase, allowing the liquid to stand for stratification, taking the upper layer, washing with water to remove residual methanol and lipase, and finally cooling and crystallizing.

[0048] In some specific embodiments, in step 1), the molecular distillation is performed as a first-stage molecular distillation, a second-stage molecular distillation, and a third-stage molecular distillation, respectively. More preferably, the specific process of the first-stage molecular distillation is as follows: preheating temperature 40-70°C, system pressure 0.1 Pa, heating wall temperature 80-100°C, scraper speed 80-110 r / min, and feed rate 5-7 mL / min; the specific process of the second-stage molecular distillation is as follows: preheating temperature 75-80°C, system pressure 0.1 Pa, heating wall temperature 120-150°C, scraper speed 90-110 r / min, and feed rate 3-5 mL / min; the specific process of the third-stage molecular distillation is as follows: system pressure 0.1 Pa, heating wall temperature 160-240°C, scraper speed 100-200 r / min, and feed rate 2-6 mL / min. More preferably, under normal circumstances, when the specific process of the first-stage molecular distillation is a preheating temperature of 50°C, a system pressure of 0.1Pa, a heating wall temperature of 90°C, a scraper speed of 90r / min, and a feed rate of 6mL / min; the specific process of the second-stage molecular distillation is: a preheating temperature of 80°C, a system pressure of 0.1Pa, a heating wall temperature of 150°C, a scraper speed of 100r / min, and a feed rate of 5mL / min; the specific process of the third-stage molecular distillation is: a system pressure of 0.1Pa, a heating wall temperature of 200°C, a scraper speed of 150r / min, and a feed rate of 4mL / min, better experimental results can be obtained at this time.

[0049] Furthermore, in step 2), the adsorption treatment is carried out at a temperature of 70-85° C. for 30-45 minutes;

[0050] And / or, in step 2), the polysaccharide gel is one or more of cellulose gel, cyclodextrin gel, and sodium alginate gel;

[0051] And / or, in step 2), the composite metal doping material is composed of a zinc-doped zirconium skeleton component and a calcium-magnesium co-deposited component in a mass ratio of 1:(0.5-0.65).

[0052] In some specific embodiments, in step 2), the adsorption treatment is performed at 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C, 80°C, 81°C, 82°C, 83°C, 84°C, or 85°C for 30 min, 32 min, 35 min, 36 min, 38 min, 40 min, 43 min, or 45 min. More preferably, in step 2), the adsorption treatment is performed at 80°C for 40 min, as this can achieve better experimental results.

[0053] In some specific embodiments, in step 2), the composite metal doping material may be composed of a zinc-doped zirconium skeleton component and a calcium-magnesium co-deposited component in a mass ratio of 1:0.5, 1:0.51, 1:0.52, 1:0.53, 1:0.54, 1:0.55, 1:0.56, 1:0.57, 1:0.58, 1:0.59, 1:0.60, 1:0.61, 1:0.62, 1:0.63, 1:0.64, or 1:0.65. Generally, in step 2), better experimental results can be achieved when the composite metal doping material is composed of a zinc-doped zirconium skeleton component and a calcium-magnesium co-deposited component in a mass ratio of 1:0.55.

[0054] Furthermore, the polysaccharide gel is prepared by a method comprising the following steps:

[0055] A) Deionized water, polysaccharide, and 3-aminophenylboronic acid are mixed uniformly, and then aldehyde-terminated polyethylene glycol is added and mixed uniformly to obtain an intermediate solution;

[0056] B) Add polyethyleneimine to the intermediate solution, ultrasonically shake, age and wash to obtain the product.

[0057] Furthermore, in step A), the mass ratio of deionized water, polysaccharide, and 3-aminophenylboronic acid is 1:(0.15-0.2):(0.03-0.05);

[0058] And / or, in step A), the polysaccharide is one or more of cellulose, cyclodextrin, and sodium alginate;

[0059] And / or, in step A), the proportion of the aldehyde-terminated polyethylene glycol in the intermediate solution is 35-60 wt %.

[0060] In some specific embodiments, in the step A), the mass ratio of deionized water, polysaccharide and 3-aminophenylboronic acid can be 1:0.15:0.03, 1:0.16:0.03, 1:0.17:0.03, 1:0.18:0.03, 1:0.19:0.03, 1:0.20:0.03, 1:0.15:0.035, 1:0.16:0.035, 1:0.17:0.035, 1:0.18:0.035, 1:0.19:0.035, 1:0.20:0.035, 1:0.15:0.04, 1:0 .16:0.04、1:0.17:0.04、1:0.18:0.04、1:0.19:0.04、1:0.20:0.04、1:0.15:0.045、1:0.16:0.045、1:0.17:0.045、1:0.18:0.045、1:0.19:0.045、1:0.20:0.045、1:0.15:0.05、1:0.16:0.05、1:0.17:0.05、1:0.18:0.05、1:0.19:0.05、1:0.20:0.05. More preferably, under normal circumstances, in step A), when the mass ratio of deionized water, polysaccharide, and 3-aminophenylboronic acid is 1:0.15:0.05, or within a floating range of 5% of the ratio, better experimental results can be achieved.

[0061] In some specific embodiments, generally, the polysaccharide is preferably composed of cyclodextrin and sodium alginate. More preferably, the polysaccharide is composed of cyclodextrin and sodium alginate in a mass ratio of 1:(5-10). More preferably, the polysaccharide is composed of cyclodextrin and sodium alginate in a mass ratio of 1:8, which can achieve better experimental results.

[0062] In some specific embodiments, in step A), the proportion of the aldehyde-terminated polyethylene glycol in the intermediate liquid can be 35wt%, 36wt%, 37wt%, 38wt%, 39wt%, 40wt%, 41wt%, 42wt%, 43wt%, 44wt%, 45wt%, 46wt%, 47wt%, 48wt%, 49wt%, 50wt%, 51wt%, 52wt%, 53wt%, 54wt%, 55wt%, 56wt%, 57wt%, 58wt%, 59wt%, or 60wt%. Generally, in step A), comparable and better experimental results can be achieved when the proportion of the aldehyde-terminated polyethylene glycol in the intermediate liquid is 50wt%, or when this proportion fluctuates within approximately 5%.

[0063] Furthermore, in step B), the molar ratio of the amino group of the polyethyleneimine to the aldehyde group of the aldehyde-terminated polyethylene glycol in the intermediate solution is 1:(0.8-1);

[0064] And / or, in step B), the Mw of the polyethyleneimine is 400-1500.

[0065] In some specific embodiments, in step B), the molar ratio of the amino groups of the polyethyleneimine to the aldehyde groups of the aldehyde-terminated polyethylene glycol in the intermediate solution may be 1:0.8, 1:0.81, 1:0.82, 1:0.83, 1:0.84, 1:0.85, 1:0.86, 1:0.87, 1:0.88, 1:0.89, 1:0.9, 1:0.91, 1:0.92, 1:0.93, 1:0.94, 1:0.95, 1:0.96, 1:0.97, 1:0.98, 1:0.99, or 1:1. Generally, in step B), better experimental results can be achieved when the molar ratio of the amino groups of the polyethyleneimine to the aldehyde groups of the aldehyde-terminated polyethylene glycol in the intermediate solution is 1:1.

[0066] In some specific embodiments, in step B), the Mw of the polyethyleneimine may be 400, 600, 800, 1000, 1200, or 1500. Generally, in step B), when the Mw of the polyethyleneimine is 600, better experimental results can be obtained.

[0067] Furthermore, the zinc-doped zirconium framework component is prepared by the following steps: preparing a zinc-zirconium mixed solution, adding glacial acetic acid and 2,6-naphthalene dicarboxylic acid to the zinc-zirconium mixed solution and mixing them evenly, heating for reaction, washing, drying, and calcining to obtain the component.

[0068] Furthermore, the calcium-magnesium co-precipitation component is prepared by the following steps: preparing a calcium-magnesium mixed solution, adding triethylamine to the calcium-magnesium mixed solution, then dropwise adding a sodium carbonate solution, then heating to remove the triethylamine, centrifuging to obtain a precipitate, washing, and drying.

[0069] Furthermore, the adsorbent is prepared by the following steps:

[0070] S1: adding a hydrochloric acid buffer solution to the polysaccharide gel, and then adding a composite metal doping material and mixing uniformly to prepare a mixed solution;

[0071] S2: Add quaternary ammonium solution dropwise to the mixed solution under continuous stirring until it becomes neutral, filter, wash and dry to obtain the product.

[0072] Furthermore, the hydrochloric acid buffer solution includes the following raw materials: deionized water, concentrated hydrochloric acid, sodium chloride, and zinc chloride.

[0073] In some specific embodiments, the preparation method of the hydrochloric acid buffer solution is as follows: weigh 29.25g of sodium chloride, put it into a 500mL beaker, add about 200mL of deionized water, and stir to completely dissolve it; then accurately measure 0.84mL of concentrated hydrochloric acid with a pipette, and slowly add it to the above sodium chloride solution while stirring; transfer the resulting solution to a 1000mL volumetric flask, rinse the beaker and glass rod with a small amount of deionized water 2-3 times, transfer the rinse liquid to the volumetric flask, add deionized water to the volumetric flask to the scale line, shake well, and finally use a pH meter to measure the pH value of the prepared buffer solution. According to the reading of the pH meter, fine-tune with dilute hydrochloric acid or sodium hydroxide solution until the pH reaches 4.0.

[0074] Example 1

[0075] The method for removing glycidyl esters in mixed tocopherols of the present embodiment comprises the following steps:

[0076] 1) The rapeseed oil deodorization distillate is charged as a reaction liquid into a reaction vessel for pretreatment (esterification treatment). A dehydrating agent and Novozym 435 immobilized lipase (10,000 U / g, 0.6 wt%) are added to the reaction vessel and mixed uniformly. Methanol is slowly added at a stirring speed of 300 rpm to carry out an esterification reaction to obtain an esterified liquid. The esterification temperature is 40°C, the alcohol-acid molar ratio is 2:1, and the reaction time is 6 hours. The dehydrating agent and immobilized lipase are recovered by filtration, and the mixture is allowed to stand for stratification. The upper layer is collected and washed with water to remove residual methanol and lipase, and finally cooled and crystallized.

[0077] The pretreated liquid was then molecularly distilled, wherein the specific process of the first-stage molecular distillation was as follows: preheating temperature 50°C, system pressure 0.1Pa, heating wall temperature 90°C, scraper speed 90r / min, and feed rate 6mL / min; the specific process of the second-stage molecular distillation was as follows: preheating temperature 80°C, system pressure 0.1Pa, heating wall temperature 150°C, scraper speed 100r / min, and feed rate 5mL / min; the specific process of the third-stage molecular distillation was as follows: system pressure 0.1Pa, heating wall temperature 200°C, scraper speed 150r / min, and feed rate 4mL / min;

[0078] The resulting liquid after molecular distillation is then mixed with anhydrous ethanol at a volume ratio of 3:1, and then poured into a chromatography column (packed with porous polystyrene PA308 basic anion resin with a bridging degree of 4%). After standing, anhydrous ethanol is added to desorb the weakly adsorbed substance, and the effluent is collected and then concentrated at 60°C to recover the ethanol. An acetic acid / ethanol solution is again added to desorb the tocopherol, and the effluent is collected and then concentrated at 60°C to recover the ethanol. The resulting liquid is chromatographed again to obtain a crude tocopherol product.

[0079] 2) 500 g of crude tocopherol and 5 g of adsorbent were mixed evenly, subjected to adsorption treatment, and filtered. HPLC-MS / MS analysis showed that the total tocopherol content in the mixed tocopherol product was 95.8%, and the glycidyl ether content was 98 μg / kg.

[0080] The adsorbent is prepared by a method comprising the following steps: taking 50g of polysaccharide gel, then adding 20g of composite metal doping material, mixing evenly, freeze-drying and pulverizing to obtain the adsorbent.

[0081] The polysaccharide gel is prepared by mixing deionized water and sodium alginate in a mass ratio of 1:0.15.

[0082] The composite metal doping material is a zinc-doped zirconium skeleton component, which is prepared by the following steps: 2.3g of zirconium chloride and 1.08g of zinc chloride are weighed and dissolved in 200mL of DMF, and then a zinc-zirconium mixed solution is prepared, 30mL of glacial acetic acid and 2.16g of 6-naphthalene dicarboxylic acid are added to the zinc-zirconium mixed solution and mixed evenly, heated to 120°C for 24h, washed with anhydrous ethanol, dried at 60°C, and then calcined at 450°C for 2h.

[0083] Example 2

[0084] The method for removing glycidyl esters in mixed tocopherols of the present embodiment comprises the following steps:

[0085] 1) The rapeseed oil deodorization distillate is charged as a reaction liquid into a reaction vessel for pretreatment (esterification treatment). A dehydrating agent and Novozym 435 immobilized lipase (10,000 U / g, 0.6 wt%) are added to the reaction vessel and mixed uniformly. Methanol is slowly added at a stirring speed of 300 rpm to carry out an esterification reaction to obtain an esterified liquid. The esterification temperature is 40°C, the alcohol-acid molar ratio is 2:1, and the reaction time is 6 hours. The dehydrating agent and immobilized lipase are recovered by filtration, and the mixture is allowed to stand for stratification. The upper layer is collected and washed with water to remove residual methanol and lipase, and finally cooled and crystallized.

[0086] The pretreated liquid was then molecularly distilled, wherein the specific process of the first-stage molecular distillation was as follows: preheating temperature 50°C, system pressure 0.1Pa, heating wall temperature 90°C, scraper speed 90r / min, and feed rate 6mL / min; the specific process of the second-stage molecular distillation was as follows: preheating temperature 80°C, system pressure 0.1Pa, heating wall temperature 150°C, scraper speed 100r / min, and feed rate 5mL / min; the specific process of the third-stage molecular distillation was as follows: system pressure 0.1Pa, heating wall temperature 200°C, scraper speed 150r / min, and feed rate 4mL / min;

[0087] The resulting liquid after molecular distillation is then mixed with anhydrous ethanol at a volume ratio of 3:1, and then poured into a chromatography column (packed with porous polystyrene PA308 basic anion resin with a bridging degree of 4%). After standing, anhydrous ethanol is added to desorb the weakly adsorbed substance, and the effluent is collected and then concentrated at 60°C to recover the ethanol. An acetic acid / ethanol solution is again added to desorb the tocopherol, and the effluent is collected and then concentrated at 60°C to recover the ethanol. The resulting liquid is chromatographed again to obtain a crude tocopherol product.

[0088] 2) 500 g of crude tocopherol and 5 g of adsorbent were mixed evenly, subjected to adsorption treatment, and filtered. HPLC-MS / MS analysis showed that the total tocopherol content in the mixed tocopherol product was 96.5%, and no glycidyl ether was detected.

[0089] The adsorbent is prepared by the following steps:

[0090] S1: Add 100 mL of hydrochloric acid buffer solution (preparation method as described above) to 50 g of polysaccharide gel, then add 20 g of composite metal doping material and mix well to prepare a mixed solution;

[0091] S2: add quaternary ammonium solution dropwise to the mixed solution under continuous stirring until it becomes neutral, filter, wash, dry, crush and grind to obtain the product.

[0092] The polysaccharide gel is prepared by a method comprising the following steps:

[0093] A) 100 mL of deionized water, 15 g of polysaccharide, and 5 g of 3-aminophenylboronic acid were mixed uniformly, and then aldehyde-terminated polyethylene glycol was added to control the proportion of aldehyde-terminated polyethylene glycol in the intermediate solution to be 50 wt %, and mixed uniformly to obtain an intermediate solution;

[0094] B) Add polyethyleneimine to the intermediate solution, control the molar ratio of the amino group of polyethyleneimine to the aldehyde group of the aldehyde-terminated polyethylene glycol in the intermediate solution to be 1:1, perform ultrasonic vibration, age, and wash to obtain the product.

[0095] The polysaccharide is composed of cyclodextrin and sodium alginate in a mass ratio of 1:8. The polyethyleneimine has an Mw of 600. The aldehyde-terminated polyethylene glycol is a dialdehyde-terminated polyethylene glycol (CHO-PEG-CHO), and the polyethylene glycol chain has an Mv of 2000. The quaternary ammonium base solution is a 45% by weight tetrabutylammonium hydroxide solution.

[0096] The composite metal doping material is a zinc-doped zirconium skeleton component, which is prepared by the following steps: 2.3g of zirconium chloride and 1.08g of zinc chloride are weighed and dissolved in 200mL of DMF, and then a zinc-zirconium mixed solution is prepared, 30mL of glacial acetic acid and 2.16g of 6-naphthalene dicarboxylic acid are added to the zinc-zirconium mixed solution and mixed evenly, heated to 120°C for 24h, washed with anhydrous ethanol, dried at 60°C, and then calcined at 450°C for 2h.

[0097] Example 3

[0098] The method for removing glycidyl esters in mixed tocopherols of the present embodiment comprises the following steps:

[0099] 1) The rapeseed oil deodorization distillate is charged as a reaction liquid into a reaction vessel for pretreatment (esterification treatment). A dehydrating agent and Novozym 435 immobilized lipase (10,000 U / g, 0.6 wt%) are added to the reaction vessel and mixed uniformly. Methanol is slowly added at a stirring speed of 300 rpm to carry out an esterification reaction to obtain an esterified liquid. The esterification temperature is 40°C, the alcohol-acid molar ratio is 2:1, and the reaction time is 6 hours. The dehydrating agent and immobilized lipase are recovered by filtration, and the mixture is allowed to stand for stratification. The upper layer is collected and washed with water to remove residual methanol and lipase, and finally cooled and crystallized.

[0100] The pretreated liquid was then molecularly distilled, wherein the specific process of the first-stage molecular distillation was as follows: preheating temperature 50°C, system pressure 0.1Pa, heating wall temperature 90°C, scraper speed 90r / min, and feed rate 6mL / min; the specific process of the second-stage molecular distillation was as follows: preheating temperature 80°C, system pressure 0.1Pa, heating wall temperature 150°C, scraper speed 100r / min, and feed rate 5mL / min; the specific process of the third-stage molecular distillation was as follows: system pressure 0.1Pa, heating wall temperature 200°C, scraper speed 150r / min, and feed rate 4mL / min;

[0101] The resulting liquid after molecular distillation is then mixed with anhydrous ethanol at a volume ratio of 3:1, and then poured into a chromatography column (packed with porous polystyrene PA308 basic anion resin with a bridging degree of 4%). After standing, anhydrous ethanol is added to desorb the weakly adsorbed substance, and the effluent is collected and then concentrated at 60°C to recover the ethanol. An acetic acid / ethanol solution is again added to desorb the tocopherol, and the effluent is collected and then concentrated at 60°C to recover the ethanol. The resulting liquid is chromatographed again to obtain a crude tocopherol product.

[0102] 2) 500 g of crude tocopherol and 5 g of adsorbent were mixed evenly, subjected to adsorption treatment, and filtered. HPLC-MS / MS analysis showed that the total tocopherol content in the mixed tocopherol product was 97.1%, and no glycidyl ether was detected.

[0103] The adsorbent is prepared by the following steps:

[0104] S1: Add 100 mL of hydrochloric acid buffer solution (preparation method as described above) to 50 g of polysaccharide gel, then add 20 g of composite metal doping material and mix well to prepare a mixed solution;

[0105] S2: add quaternary ammonium solution dropwise to the mixed solution under continuous stirring until it becomes neutral, filter, wash, dry, crush and grind to obtain the product.

[0106] The polysaccharide gel is prepared by a method comprising the following steps:

[0107] A) 100 mL of deionized water, 15 g of polysaccharide, and 5 g of 3-aminophenylboronic acid were mixed uniformly, and then aldehyde-terminated polyethylene glycol was added to control the proportion of aldehyde-terminated polyethylene glycol in the intermediate solution to be 50 wt %, and mixed uniformly to obtain an intermediate solution;

[0108] B) Add polyethyleneimine to the intermediate solution, control the molar ratio of the amino group of polyethyleneimine to the aldehyde group of the aldehyde-terminated polyethylene glycol in the intermediate solution to be 1:1, perform ultrasonic vibration, age, and wash to obtain the product.

[0109] The polysaccharide is composed of cyclodextrin and sodium alginate in a mass ratio of 1:8. The polyethyleneimine has an Mw of 600. The aldehyde-terminated polyethylene glycol is a dialdehyde-terminated polyethylene glycol (CHO-PEG-CHO), and the polyethylene glycol chain has an Mv of 2000. The quaternary ammonium base solution is a 45% by weight tetrabutylammonium hydroxide solution.

[0110] The composite metal doping material consists of a zinc-doped zirconium skeleton component and a calcium-magnesium co-deposition component in a mass ratio of 1:0.55.

[0111] The zinc-doped zirconium framework component was prepared by the following steps: 2.3 g of zirconium chloride and 1.08 g of zinc chloride were weighed and dissolved in 200 mL of DMF, and then a zinc-zirconium mixed solution was prepared. 30 mL of glacial acetic acid and 2.16 g of 6-naphthalene dicarboxylic acid were added to the zinc-zirconium mixed solution and mixed evenly. The mixture was heated to 120° C. and reacted for 24 h. The mixture was washed with anhydrous ethanol, dried at 60° C., and then calcined at 450° C. for 2 h.

[0112] The calcium-magnesium co-precipitation component is prepared by the following steps: weighing 2.2g of calcium chloride and 0.19g of magnesium chloride, adding them to a mixed solvent containing 50mL of ethanol and 10mL of deionized water, mixing them evenly to obtain a calcium-magnesium mixed solution, then adding 50g of triethylamine to the calcium-magnesium mixed solution, then dropwise adding a slightly excess amount of sodium carbonate solution, then heating to remove the triethylamine, centrifuging to obtain a precipitate, washing, and drying.

[0113] Control group 1

[0114] The method for removing glycidyl esters from the mixed tocopherols in the control group comprises the following steps:

[0115] 1) The rapeseed oil deodorization distillate is charged as a reaction liquid into a reaction vessel for pretreatment (esterification treatment). A dehydrating agent and Novozym 435 immobilized lipase (10,000 U / g, 0.6 wt%) are added to the reaction vessel and mixed uniformly. Methanol is slowly added at a stirring speed of 300 rpm to carry out an esterification reaction to obtain an esterified liquid. The esterification temperature is 40°C, the alcohol-acid molar ratio is 2:1, and the reaction time is 6 hours. The dehydrating agent and immobilized lipase are recovered by filtration, and the mixture is allowed to stand for stratification. The upper layer is collected and washed with water to remove residual methanol and lipase, and finally cooled and crystallized.

[0116] The pretreated liquid was then molecularly distilled, wherein the specific process of the first-stage molecular distillation was as follows: preheating temperature 50°C, system pressure 0.1Pa, heating wall temperature 90°C, scraper speed 90r / min, and feed rate 6mL / min; the specific process of the second-stage molecular distillation was as follows: preheating temperature 80°C, system pressure 0.1Pa, heating wall temperature 150°C, scraper speed 100r / min, and feed rate 5mL / min; the specific process of the third-stage molecular distillation was as follows: system pressure 0.1Pa, heating wall temperature 200°C, scraper speed 150r / min, and feed rate 4mL / min;

[0117] The resulting liquid after molecular distillation is then mixed with anhydrous ethanol at a volume ratio of 3:1, and then poured into a chromatography column (packed with porous polystyrene PA308 basic anion resin with a bridging degree of 4%). After standing, anhydrous ethanol is added to desorb the weakly adsorbed substance, and the effluent is collected and then concentrated at 60°C to recover the ethanol. An acetic acid / ethanol solution is again added to desorb the tocopherol, and the effluent is collected and then concentrated at 60°C to recover the ethanol. The resulting liquid is chromatographed again to obtain a crude tocopherol product.

[0118] 2) 500 g of crude tocopherol and 5 g of adsorbent (activated clay, model 1060FF) were mixed evenly, subjected to adsorption treatment, and filtered. HPLC-MS / MS analysis showed that the total tocopherol content in the mixed tocopherol product was 85.3%, and the glycidyl ether content was 1736 μg / kg.

[0119] Control group 2

[0120] The method for removing glycidyl esters from the mixed tocopherols in the control group comprises the following steps:

[0121] 1) The rapeseed oil deodorization distillate is charged as a reaction liquid into a reaction vessel for pretreatment (esterification treatment). A dehydrating agent and Novozym 435 immobilized lipase (10,000 U / g, 0.6 wt%) are added to the reaction vessel and mixed uniformly. Methanol is slowly added at a stirring speed of 300 rpm to carry out an esterification reaction to obtain an esterified liquid. The esterification temperature is 40°C, the alcohol-acid molar ratio is 2:1, and the reaction time is 6 hours. The dehydrating agent and immobilized lipase are recovered by filtration, and the mixture is allowed to stand for stratification. The upper layer is collected and washed with water to remove residual methanol and lipase, and finally cooled and crystallized.

[0122] The pretreated liquid was then molecularly distilled, wherein the specific process of the first-stage molecular distillation was as follows: preheating temperature 50°C, system pressure 0.1Pa, heating wall temperature 90°C, scraper speed 90r / min, and feed rate 6mL / min; the specific process of the second-stage molecular distillation was as follows: preheating temperature 80°C, system pressure 0.1Pa, heating wall temperature 150°C, scraper speed 100r / min, and feed rate 5mL / min; the specific process of the third-stage molecular distillation was as follows: system pressure 0.1Pa, heating wall temperature 200°C, scraper speed 150r / min, and feed rate 4mL / min;

[0123] The resulting liquid after molecular distillation is then mixed with anhydrous ethanol at a volume ratio of 3:1, and then poured into a chromatography column (packed with porous polystyrene PA308 basic anion resin with a bridging degree of 4%). After standing, anhydrous ethanol is added to desorb the weakly adsorbed substance, and the effluent is collected and then concentrated at 60°C to recover the ethanol. An acetic acid / ethanol solution is again added to desorb the tocopherol, and the effluent is collected and then concentrated at 60°C to recover the ethanol. The resulting liquid is chromatographed again to obtain a crude tocopherol product.

[0124] 2) 500 g of crude tocopherol and 5 g of adsorbent were mixed uniformly, subjected to adsorption treatment, and filtered to obtain a mixed tocopherol product. The total tocopherol content of the mixed tocopherol product was determined by high performance liquid chromatography-mass spectrometry to be 88.2 μg / kg, and the glycidyl ether content was 518 μg / kg.

[0125] The adsorbent is a composite metal doped material, specifically a zinc-doped zirconium skeleton component, which is prepared by the following steps: 2.3g of zirconium chloride and 1.08g of zinc chloride are weighed and dissolved in 200ml of DMF, and then a zinc-zirconium mixed solution is prepared, 30ml of glacial acetic acid and 2.16g of 6-naphthalene dicarboxylic acid are added to the zinc-zirconium mixed solution and mixed evenly, heated to 120°C for reaction for 24h, washed with anhydrous ethanol, dried at 60°C, and then calcined at 450°C for 2h.

[0126] Performance testing

[0127] 1. Adsorption stability test

[0128] α-tocopherol with a purity of 98%, β-tocopherol with a purity of 98%, and γ-tocopherol with a purity of 98% were mixed in a mass ratio of 1:1:1, and glycidyl palmitate (purity of 99%) was added to prepare a mixed tocopherol test solution (containing 5000 μg / kg of glycidyl palmitate).

[0129] To 100 g of the mixed tocopherol test solution, the adsorbents of Examples 1-3 and Control Groups 1-2 were added (the addition amount was 1 wt%).

[0130] Adsorb at 105℃ for 90min, take out and stir evenly every 10min during the adsorption period, calculate the adsorption rate after the adsorption is completed, and desorb the adsorbent. Replace the test solution and repeat the test 10 times to observe the adsorption stability of the adsorbent. The test results are as follows: Figure 1 shown.

[0131] 2. Take the polysaccharide gel of Example 3 (without adding hydrochloric acid buffer solution to dissolve) and the adsorbent (i.e. polysaccharide gel@composite metal doping material), and the hybrid formation process of the adsorbent is as follows: Figure 2 As shown, the appearance is Figure 3 As shown, it can be seen that the polysaccharide gel after being doped with the composite metal doping material re-solidifies, the cross-linking density increases, and the adsorption performance is enhanced.

[0132] 3. The adsorbents of Examples 1-3 were tested by scanning electron microscopy. The results were as follows: Figure 4-6 As shown ( Figure 4 For Example 1, Figure 5 For Example 2, Figure 6 As shown in Example 3, the outer layer of the particles is wrapped with porous polysaccharide gel, and the inner layer is a composite metal-doped material, which has a higher adsorption removal rate than traditional adsorption materials such as activated carbon and bentonite.

[0133] Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present invention.

Claims

1. A method for removing glycidyl esters from mixed tocopherols, characterized in that: The steps include: 1) Esterifying the deodorized vegetable oil distillate, followed by molecular distillation and chromatography to obtain a crude tocopherol product; the esterification process comprises adding a dehydrating agent and immobilized lipase to the deodorized vegetable oil distillate, mixing them uniformly, slowly adding methanol to carry out an esterification reaction to obtain an esterified liquid, filtering to recover the dehydrating agent and immobilized lipase, allowing the liquid to stand for separation, collecting the upper layer, washing with water to remove residual methanol and lipase, and finally cold precipitation for crystallization; 2) Mix the crude tocopherol and the adsorbent evenly, perform adsorption treatment, and filter; The adsorbent is prepared by the following steps: S1: adding a hydrochloric acid buffer solution to the polysaccharide gel, and then adding a composite metal doping material and mixing uniformly to prepare a mixed solution, wherein the composite metal doping material is composed of a zinc-doped zirconium skeleton component and a calcium-magnesium co-deposited component in a mass ratio of 1:(0.5-0.65); S2: add quaternary ammonium solution dropwise to the mixed solution under continuous stirring until it becomes neutral, filter, wash and dry to obtain the product; The polysaccharide gel is prepared by a method comprising the following steps: A) mixing deionized water, polysaccharide, and 3-aminophenylboronic acid, then adding aldehyde-terminated polyethylene glycol, and mixing uniformly to obtain an intermediate solution; B) adding polyethyleneimine to the intermediate solution, ultrasonically shaking, aging, and washing to obtain the obtained solution; The zinc-doped zirconium framework component is prepared by the following steps: preparing a zinc-zirconium mixed solution, adding glacial acetic acid and 2,6-naphthalene dicarboxylic acid to the zinc-zirconium mixed solution, mixing evenly, heating to react, washing, drying, and calcining to obtain the obtained product; The calcium-magnesium co-precipitation component is prepared by the following steps: preparing a calcium-magnesium mixed solution, adding triethylamine to the calcium-magnesium mixed solution, then dropwise adding a sodium carbonate solution, then heating to remove the triethylamine, centrifuging to obtain a precipitate, washing, and drying.

2. The method for removing glycidyl esters from mixed tocopherols according to claim 1, wherein: In step 1), the vegetable oil is one of rapeseed oil, soybean oil, corn oil, olive oil, cottonseed oil, sunflower oil, and tea oil; And / or, in the step 1), the molecular distillation is performed by first-stage molecular distillation, second-stage molecular distillation and third-stage molecular distillation respectively.

3. The method for removing glycidyl esters from mixed tocopherols according to claim 1, wherein: In step 2), the adsorption treatment is carried out at a temperature of 70-85° C. for 30-45 minutes; And / or, in step 2), the polysaccharide gel is one or more of cellulose gel, cyclodextrin gel, and sodium alginate gel.

4. The method for removing glycidyl esters from mixed tocopherols according to claim 1, wherein: In step A), the mass ratio of deionized water, polysaccharide, and 3-aminophenylboronic acid is 1:(0.15-0.2):(0.03-0.05); And / or, in step A), the polysaccharide is one or more of cellulose, cyclodextrin, and sodium alginate; And / or, in step A), the proportion of the aldehyde-terminated polyethylene glycol in the intermediate solution is 35-60 wt %.

5. The method for removing glycidyl esters from mixed tocopherols according to claim 1, wherein: In the step B), the molar ratio of the amino group of the polyethyleneimine to the aldehyde group of the aldehyde-terminated polyethylene glycol in the intermediate solution is 1:(0.8-1); And / or, in step B), the Mw of the polyethyleneimine is 400-1500.

6. The method for removing glycidyl esters from mixed tocopherols according to claim 1, wherein: The hydrochloric acid buffer solution comprises the following raw materials: deionized water, concentrated hydrochloric acid, sodium chloride and zinc chloride.

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