A method for preparing glucuronolactone

Abstract

The invention discloses a method for preparing glucuron lactone, which is used to solve the problems of low glucuron lactone yield, acetic acid corrosion to equipment, large energy consumption, and difficulty in recovering acetic acid. A method for preparing glucuron lactone, comprising adding whole bacteria containing inositol oxidase to inositol feed liquid for conversion, purifying and concentrating the conversion liquid to obtain a concentrated liquid; adding lactic acid to the concentrated liquid for lactonization reaction, and concentrating, crystallizing, filtering, washing, and drying the reaction product to obtain a glucuron lactone product. Inositol feed liquid is the raw material of glucuron lactone product, and lactic acid is added for lactonization reaction, so that the crystallization yield of glucuron lactone is significantly improved, the yield is greater than 80%, and the purity of glucuron lactone is greater than 95%; the influence of lactic acid on equipment is significantly reduced compared with acetic acid; at the same time, the process is environmentally friendly, and the impact on the environment and human health is reduced.

Description

Technical Field

[0001] The invention belongs to the pharmaceutical field, and in particular relates to a method for preparing glucuronolactone. Background Art

[0002] The full name of glucuronolactone in Chinese is glucuronolactone, commonly known as liver taylor, with the molecular formula of C6H8O6, and its chemical composition is: D(+)-furanoglucuronic acid γ-lactone, English name: [D(+)-Glucofuranurono-6,3-lactone]. As a liver detoxifier and immune function regulator, glucuronolactone is a conventional liver protection medicine; glucuronolactone and its subsequent products are also the main additives of functional beverages and foods, weight loss drugs, cosmetics, etc., which have the effects of replenishing physical energy, improving hypoxia, nourishing skin, and delaying aging.

[0003] The main method for industrial production of glucuron-lactone at present is the nitric acid oxidation method starting from starch. The process is as follows: starch is added to nitric acid with a content of about 80% (V / V) to oxidize to obtain oxidized starch, the starch oxidation solution is heated and pressurized under acidic conditions to hydrolyze to obtain the hydrolyzate of oxidized starch, the hydrolyzate is concentrated under reduced pressure to a Baume degree of 44-49, acetic acid is added for esterification, the esterification mixture is cooled to 30-45°C and then allowed to stand for 16-20 hours and then concentrated under reduced pressure to a Baume degree of 40-45, and gradually cooled to -4 to -8°C. The total cooling and crystallization time is generally 70-80 hours, and the crystals are filtered by high-speed centrifugation to obtain a crude glucuron-lactone product with a purity of 80-90%. The yield of glucuron lactone obtained by this process is low, and its yield is only about 14%; acetic acid is added in the production process of glucuron lactone, and acetic acid is easy to corrode equipment, and the equipment control requirements are strict. The energy consumption in the production process is large and it is difficult to recover acetic acid; and the crude product extraction process has large losses, the production cost is high, it is difficult to meet the needs of the market, and it is also highly polluting to the environment. Summary of the invention

[0004] The purpose of the present invention is to solve at least one technical problem such as low yield of glucuron lactone, corrosion of acetic acid to equipment, large energy consumption, difficulty in recovering acetic acid, and provide a method for preparing glucuron lactone.

[0005] In a first aspect, the present invention provides a method for preparing glucuronolactone, comprising the following steps:

[0006] Adding whole bacteria containing inositol oxidase to the inositol feed liquid for transformation, filtering the transformation liquid to obtain a filtrate, and desalting, decolorizing and concentrating the filtrate to obtain a concentrated solution;

[0007] The concentrated solution is added with lactonic acid for lactonization reaction, and the reaction product is concentrated, crystallized, filtered, washed and dried to obtain the glucuron lactone product.

[0008] By adopting the above technical scheme, inositol liquid is used as the raw material of glucuron lactone product, and lactic acid is added for lactonization reaction, so that the crystallization yield of glucuron lactone is significantly improved, the yield is greater than 80%, and the purity of glucuron lactone is greater than 95%; the impact of lactic acid on equipment is significantly reduced compared with acetic acid; at the same time, the process is environmentally friendly and has reduced impact on the environment and human health.

[0009] Preferably, the step of adding whole bacteria containing inositol oxidase to the inositol liquid for conversion comprises:

[0010] The inositol content in the inositol liquid is 1-10wt%; the conversion temperature is 30-40°C, the conversion pH is 8.0-9.0, and the conversion time is 8-12h.

[0011] By adopting the above technical scheme, whole bacteria containing inositol oxidase are used to convert inositol into glucuronic acid, so that the conversion efficiency and the yield of glucuronic acid are significantly improved; at the same time, there are no other by-products in the inositol liquid, and the quality of the produced glucuronolactone is better.

[0012] Preferably, the conversion liquid is filtered to obtain a filtrate comprising:

[0013] The conversion liquid is filtered through a ceramic membrane to obtain a ceramic membrane filtrate, and the ceramic membrane filtrate is filtered through an ultrafiltration membrane assembly to collect the filtrate.

[0014] By adopting the above technical scheme, whole cells containing inositol oxidase in the conversion liquid can be separated by ceramic membrane filtration and can be repeatedly added and reused; large molecular organic matter can be separated and removed by ultrafiltration membrane filtration, and the subsequent concentration process is convenient. The production efficiency of glucuron-lactone is improved, and the yield and quality are also improved.

[0015] Preferably, the pore size of the ceramic membrane is 20-100 nm; and / or the pore size of the ultrafiltration membrane used in the ultrafiltration membrane assembly is 5000-20000 Da.

[0016] By adopting the above technical solution, the pore sizes of ceramic membranes and ultrafiltration membranes are limited to meet process requirements.

[0017] Preferably, the filtrate is desalted, decolorized and concentrated to obtain a concentrate comprising:

[0018] The filtrate is desalted by a cation exchange resin to obtain a desalted liquid;

[0019] The desalted liquid is decolorized by adsorption by a macroporous resin to obtain a decolorized liquid;

[0020] The decolorized liquid passes through a nanofiltration membrane assembly to collect a nanofiltration concentrate;

[0021] The nanofiltration concentrate is concentrated in a concentrator to obtain the concentrate.

[0022] By adopting the above technical scheme, the ultrafiltration membrane filtrate is desalted by a cation exchange resin, decolorized by a macroporous resin, and concentrated by a nanofiltration membrane assembly, and then further concentrated by vacuum in a concentrator to obtain a high-concentration glucuronic acid desalted and decolorized liquid, which is beneficial to the lactonization reaction of the glucuronic acid liquid, thereby improving the reaction efficiency and the quality of glucuron lactone.

[0023] Preferably, the cation exchange resin is a strongly acidic cation exchange resin, and the conductivity of the desalted solution is <7000us / cm;

[0024] The nanofiltration membrane pore size used in the nanofiltration membrane assembly is 150-300Da;

[0025] The solid content of the nanofiltration concentrate is 10-15 wt %, wherein the glucuronic acid content is 50-150 g / L, and the solid content of the concentrate is 50-70 w %.

[0026] By adopting the above technical scheme, the conductivity of the desalted liquid is controlled, which is beneficial to improving the quality of the glucuron lactone product; the pore size of the nanofiltration membrane is controlled to intercept the glucuronic acid molecules, which is beneficial to the initial concentration; further concentration in the concentrator increases the content of glucuronic acid, which is beneficial to improving the efficiency of the lactonization reaction and shortening the production time.

[0027] Preferably, during the lactonization reaction, the amount of lactic acid added is 0.5-3.0 times the volume of the concentrated solution, the lactonization reaction temperature is 50-70° C., and the reaction time is 3-6 h.

[0028] By adopting the above technical scheme, by regulating the lactonization reaction conditions, improving the efficiency of the glucuronic acid lactonization reaction, and shortening the reaction time, a glucuronolactone product with better quality can be obtained.

[0029] Preferably, the reaction product is concentrated, comprising:

[0030] The reaction product is concentrated under vacuum, the vacuum concentration temperature is 50-70° C., the vacuum degree is <-0.09 MPa, and the volume of the distilled water is 30-50% of the volume of the concentrated liquid.

[0031] By adopting the above technical solution, the glucuron-lactone liquid is vacuum concentrated to evaporate excess water, thereby improving the efficiency of subsequent cooling crystallization and shortening the crystallization time.

[0032] Preferably, the crystallization is dynamic gradient cooling crystallization, the cooling rate is 5-10°C / h, and the crystallization termination temperature is 5-15°C.

[0033] By adopting the above technical solution and the dynamic gradient cooling crystallization method, the glucuron lactone crystals obtained by crystallization have uniform particle sizes, and the crystals are not easy to wrap impurities. At the same time, it is easy to filter and obtain the glucuron lactone product, and the crystallization yield is greater than 80%.

[0034] In a second aspect, the present invention further provides a glucuron-lactone prepared by any of the above-mentioned glucuron-lactone preparation methods.

[0035] By adopting the above technical scheme, the glucuron lactone product obtained by the above glucuron lactone preparation method has uniform particle size and a glucuron lactone content of more than 95%.

[0036] Instruction Manual

[0037] Figure 1 This is the liquid chromatogram of the glucuronolactone crystals prepared in Example 2. DETAILED DESCRIPTION

[0038] The present invention is described in further detail below in conjunction with the examples. For the sake of simplicity of description, this document cannot enumerate all the alternative technical features and implementation schemes included in the present invention, so those skilled in the art should know that any technical features and implementation schemes in the present embodiment do not limit the scope of protection of the present invention, and the scope of protection includes any alternative technical features and implementation schemes taken by all those skilled in the art without creative work. Specifically, the implementation schemes obtained by replacing any technical feature in the present invention or combining any two or more technical features provided by the present invention should be within the scope of protection of the present invention. Those who do not specify the specific techniques and conditions in the examples are carried out according to the techniques and conditions described in the literature in this field or according to the product instructions, and the reagents or instruments used are not indicated by the manufacturer, and are all conventional products that can be purchased commercially.

[0039] The relevant components and materials used in the following embodiments are specifically as follows:

[0040] Ultrafiltration membrane assembly, nanofiltration membrane assembly: Both ultrafiltration membrane and nanofiltration membrane are roll-type membranes, which have large effective membrane area and large water production. Generally, the water production of a 4-inch roll-type nanofiltration membrane is 40m 3 / d; excellent desalination performance and can be filtered under low pressure conditions.

[0041] The cation exchange resin is D-67 strongly acidic cation exchange resin.

[0042] The macroporous resin is LS-109D macroporous resin.

[0043] The whole bacteria containing inositol oxidase used in the following examples are specifically the engineered bacteria expressing functional proteins disclosed in CN109423469A.

[0044] The embodiment of the present invention provides a method for preparing glucuronolactone, comprising the following steps:

[0045] Adding whole bacteria containing inositol oxidase to the inositol feed liquid for transformation, filtering the transformation liquid to obtain a filtrate, and desalting, decolorizing and concentrating the filtrate to obtain a concentrated solution;

[0046] The concentrated solution is added with lactonic acid for lactonization reaction, and the reaction product is concentrated, crystallized, filtered, washed and dried to obtain the glucuron lactone product.

[0047] Specifically, in the above embodiment, whole bacteria containing inositol oxidase are added to the inositol feed solution for conversion, wherein the inositol feed solution can be configured by a technician. For example, inositol is dissolved in water and configured as 1wt-10wt% inositol feed solution. The amount of inositol oxidase whole bacteria added can be selected to make the system bacterial concentration reach 25-40OD. Specific conversion conditions can be referred to as follows: conversion temperature is 30-40°C, conversion pH is 8.0-9.0, and conversion time is 8-12h. For example, in some embodiments of the present invention, in the inositol feed solution, the inositol content can be specifically 1wt%, 5wt%, 10wt%; the conversion temperature can be specifically 30°C, 35°C, 40°C; the conversion pH can be specifically 8.0, 8.5, 9.0; the conversion time can be specifically 8h, 10h, 12h.

[0048] Specifically, in the above embodiments, the conversion liquid is filtered to obtain a filtrate, including: the conversion liquid is filtered through a ceramic membrane to obtain a ceramic membrane filtrate, and the ceramic membrane filtrate is filtered through an ultrafiltration membrane assembly to collect the filtrate. The pore size of the ceramic membrane is 20-100nm; the pore size of the ultrafiltration membrane used in the ultrafiltration membrane assembly is 10000-20000Da. For example, in some embodiments of the present invention, the pore size of the ceramic membrane can be specifically 20nm, 60nm, 100nm; the pore size of the ultrafiltration membrane can be specifically 10000Da, 15000Da, 20000Da.

[0049] Specifically, in the above embodiment, the filtrate is desalted, decolorized, and concentrated to obtain a concentrated solution, including: the filtrate is desalted by a cation exchange resin to obtain a desalted solution; the desalted solution is adsorbed and decolorized by a macroporous resin to obtain a decolorized solution; the decolorized solution is passed through a nanofiltration membrane assembly to collect a nanofiltration concentrated solution, and the nanofiltration concentrated solution is concentrated in a concentrator to obtain the concentrated solution. The cation exchange resin is a strongly acidic cation exchange resin, and the conductivity of the desalted solution is <5000us / cm; the nanofiltration membrane pore size used in the nanofiltration membrane assembly is 150-300Da; the solid content of the nanofiltration concentrated solution is 10-15wt%, wherein the glucuronic acid content is 50-150g / L; the solid content of the concentrated solution is 50-70wt%. For example, in some embodiments, the conductivity of the desalted liquid can be specifically 5000us / cm, 4000us / cm, 3000us / cm; the pore size of the nanofiltration membrane can be specifically 150Da, 250Da, 300Da; the solid content of the nanofiltration concentrate can be specifically 10wt%, 13wt%, 15wt%, and the glucuronic acid content can be specifically 50g / L, 100g / L, 150g / L; the solid content of the concentrate can be specifically 50wt%, 60wt%, 70wt%.

[0050] Specifically, in the above embodiment, during the lactonization reaction, the amount of lactic acid added is 0.5-3.0 times the volume of the concentrate, the lactonization reaction temperature is 50-70°C, and the reaction time is 3-6h. For example, in some embodiments, the amount of lactic acid added can be specifically 0.5 times, 1.0 times, 1.5 times, 2 times, 3 times the volume of the concentrate; the lactonization reaction temperature can be specifically 50°C, 60°C, 70°C; the reaction time can be specifically 3h, 4h, 6h.

[0051] Specifically, in the above embodiment, the reaction product is concentrated, including: the reaction product is vacuum concentrated, the vacuum concentration temperature is 50-70°C, the vacuum degree is <-0.09MPa, and the volume of evaporated water is 30-50% of the volume of the concentrated solution. For example, in some embodiments, the vacuum concentration temperature can be specifically 50°C, 60°C, 70°C; the volume of evaporated water can be specifically 30%, 40%, 50% of the volume of the concentrated solution.

[0052] Specifically, in the above embodiment, the crystallization is a dynamic gradient cooling crystallization, the cooling rate is 5-10°C / h, and the crystallization termination temperature is 5-15°C. For example, in some embodiments, the cooling rate can be specifically 5°C / h, 8°C / h, 10°C / h; the crystallization termination temperature can be specifically 5°C, 10°C, 15°C.

[0053] In order to better illustrate the technical solution of the present invention, the present invention also provides the following specific examples. It should be understood that the raw materials used in the following examples are all commercially available raw materials unless otherwise specified.

[0054] Example 1

[0055] This embodiment provides a method for preparing glucuronolactone, comprising the following steps:

[0056] Step (1), adding whole bacteria containing inositol oxidase to 60L of inositol feed liquid containing 1wt% inositol, making the system bacterial concentration reach 30OD, converting for 12h under the conditions of temperature of 30°C and pH of 8.0, obtaining 62L of glucuronic acid conversion liquid with a solid content of 1% after the conversion is completed, filtering the glucuronic acid conversion liquid through a ceramic membrane with a pore size of 20nm at an inlet pressure of 0.5MPa, an outlet pressure of 0.3MPa, and a flow rate of 60L / h to obtain 63L of ceramic membrane filtrate with a solid content of 1%; filtering the ceramic membrane filtrate through an ultrafiltration membrane assembly with a pore size of 10000Da at an inlet pressure of 0.5MPa, an outlet pressure of 0.3MPa, and a flow rate of 150L / h, collecting 65L of filtrate with a solid content of 1% was collected; the filtrate was desalted by a cation exchange resin at a flow rate of 1.5BV to obtain a desalted liquid, and the conductivity of the desalted liquid was 5000us / cm; the desalted liquid was decolorized by a macroporous resin at a flow rate of 2BV to obtain a decolorized liquid; the decolorized liquid was preliminarily concentrated by a nanofiltration membrane assembly with a pore size of 150Da at an inlet pressure of 3MPa, an outlet pressure of 2.5MPa, and a flow rate of 40L / h to obtain 4L of nanofiltration membrane concentrate, with a solid content of 13wt% and a glucuronic acid content of 126g / L; the nanofiltration membrane concentrate was concentrated under reduced pressure at a temperature of 70°C and a vacuum degree of -0.09MPa to obtain 0.9L of glucuronic acid concentrate with a solid content of 62%;

[0057] Step (2), adding 1.8 L of lactic acid to the concentrated solution obtained in step (1) to carry out a lactonization reaction, the lactonization reaction temperature is 70° C., the reaction product obtained after reacting for 4 hours is vacuum concentrated, the vacuum concentration temperature is 70° C., the vacuum degree is -0.09 MPa, and the volume of water evaporated is 0.35 L; crystallization is carried out under the condition of a cooling rate of 5° C. / h, and the crystallization termination temperature is 5° C.; the crystallization mixture is filtered, the solid is washed with 0.5 L of anhydrous ethanol, and vacuum dried to obtain a glucuron lactone product.

[0058] The purity of the glucuronolactone obtained in Example 1 was 98.2%, the crystallization yield was 84.5%, and the crystal particle size was 20 meshes.

[0059] Example 2

[0060] This embodiment provides a method for preparing glucuronolactone, comprising the following steps:

[0061] Step (1), adding whole bacteria containing inositol oxidase to 60L of inositol feed liquid containing 5wt% inositol, making the system bacterial concentration reach 35OD, converting for 10h under the conditions of temperature of 35°C and pH of 8.5, and obtaining 61L of glucuronic acid conversion liquid with a solid content of 6% after the conversion is completed; filtering the glucuronic acid conversion liquid through a ceramic membrane with a pore size of 60nm at an inlet pressure of 0.5MPa, an outlet pressure of 0.3MPa, and a flow rate of 80L / h to obtain 75L of ceramic membrane filtrate with a solid content of 5%; filtering the ceramic membrane filtrate through an ultrafiltration membrane assembly with a pore size of 15000Da at an inlet pressure of 0.5MPa, an outlet pressure of 0.3MPa, and a flow rate of 150L / h. Filter, collect 94L of filtrate with a solid content of 4%; desalt the filtrate through a cation exchange resin at a flow rate of 1.5BV to obtain a desalted solution, and the conductivity of the desalted solution is 4000us / cm; the desalted solution is decolorized through a macroporous resin at a flow rate of 2BV to obtain a decolorized solution; the decolorized solution is initially concentrated through a nanofiltration membrane assembly with a pore size of 250Da at an inlet pressure of 3.0MPa, an outlet pressure of 2.5MPa, and a flow rate of 40L / h to obtain 21L of nanofiltration membrane concentrate, with a solid content of 13wt% and a glucuronic acid content of 128g / L; the nanofiltration membrane concentrate is further concentrated at a temperature of 70°C and a vacuum degree of -0.09MPa to obtain 4.5L of a concentrate with a solid content of 60wt%;

[0062] Step (2), adding lactic acid solution to the concentrated solution obtained in step (1) for lactonization reaction, wherein the amount of lactic acid solution added is twice the volume of the concentrated solution, the lactonization reaction temperature is 60°C, and the reaction product obtained after reacting for 4 hours is vacuum concentrated, the vacuum concentration temperature is 60°C, the vacuum degree is <-0.09MPa, and the volume of water evaporated is 40% of the volume of the concentrated solution; crystallization is carried out under the condition of a cooling rate of 10°C / h, and the crystallization termination temperature is 10°C; the crystallization mixture is filtered, washed with anhydrous ethanol, and vacuum dried to obtain the glucuron lactone product.

[0063] The purity of the glucuronolactone obtained in Example 2 was 98.5%, the crystallization yield was 87.6%, and the crystal particle size was 25 meshes.

[0064] Example 3

[0065] This embodiment provides a method for preparing glucuronolactone, comprising the following steps:

[0066] Step (1), adding whole bacteria containing inositol oxidase to 60L of inositol feed liquid containing 10wt% inositol, making the system bacterial concentration reach 25OD, converting at a temperature of 40°C and a pH of 9.0 for 8h, and obtaining 62L of glucuronic acid conversion liquid with a solid content of 10% after the conversion is completed; filtering the glucuronic acid conversion liquid through a ceramic membrane with a pore size of 100nm at an inlet pressure of 0.5MPa, an outlet pressure of 0.3MPa, and a flow rate of 80L / h to obtain 78L of ceramic membrane filtrate with a solid content of 8%; filtering the ceramic membrane filtrate through an ultrafiltration membrane component with a pore size of 20000Da at an inlet pressure of 0.5MPa, an outlet pressure of 0.3MPa, and a flow rate of 150L / h. Filter and collect 96L of filtrate with a solid content of 6.5%; desalt the filtrate through a cation exchange resin at a flow rate of 1.5BV to obtain a desalted solution, and the conductivity of the desalted solution is 3000us / cm; decolorize the desalted solution through a macroporous resin at a flow rate of 2BV to obtain a decolorized solution; the decolorized solution is initially concentrated through a nanofiltration membrane assembly with a pore size of 300Da at an inlet pressure of 3.0MPa, an outlet pressure of 2.5MPa, and a flow rate of 40L / h to obtain 40L of nanofiltration membrane concentrated solution, with a solid content of 15wt% and a glucuronic acid content of 150g / L; the nanofiltration membrane concentrated solution is further concentrated at a temperature of 50°C and a vacuum degree of -0.09MPa to obtain 8.5L of concentrated solution with a solid content of 70wt%;

[0067] Step (2), adding lactic acid solution to the concentrated solution obtained in step (1) for lactonization reaction, wherein the amount of lactic acid solution added is 3 times the volume of the concentrated solution, the lactonization reaction temperature is 70°C, and the reaction product obtained after reacting for 6 hours is vacuum concentrated, the vacuum concentration temperature is 70°C, the vacuum degree is <-0.09MPa, and the volume of water evaporated is 50% of the volume of the concentrated solution; crystallization is carried out under the condition of a cooling rate of 15°C / h, and the crystallization termination temperature is 15°C; the crystallization mixture is filtered, washed with anhydrous ethanol, and vacuum dried to obtain the glucuron lactone product.

[0068] The purity of the glucuronolactone obtained in Example 3 was 96.4%, the crystallization yield was 84.7%, and the crystal particle size was 25 meshes.

[0069] Comparative Example 1

[0070] Comparative Example 1 provides a method for preparing glucuronolactone, which differs from Example 2 in that an equal amount of lactic acid in Comparative Example 1 is replaced by acetic acid, and other conditions remain unchanged.

[0071] The purity of the glucuron-lactone obtained in Comparative Example 1 was 71.4%, the crystallization yield was 52.5%, and the crystal particle size was 30 meshes.

[0072] In the lactonization reaction and vacuum concentration process, due to the volatile nature of acetic acid, a large amount of acetic acid vapor is produced, and the equipment is seriously corroded. At the same time, after the acetic acid volatilizes, the amount of effective reactants is reduced. If acetic acid is not supplemented, the yield of the product is greatly reduced. In addition, since the solid content of glucuronic acid in this comparative example is 50-70%, which is equivalent to 20-30 degrees Baume, the concentration is relatively low, and the concentrated solution concentration usually required for the esterification reaction of acetic acid and glucuronic acid is high, which takes a long time in the concentration process and consumes a lot of energy. Finally, in the vacuum concentration process, due to the presence of acetic acid, the color of the system deepens, the quality of the glucuron lactone product decreases, and the crystal appearance is dark and has no glossiness. The crude glucuron lactone crystals prepared by Example 2 using lactic acid have a white and bright appearance, and the crystal particle size is uniform and easy to filter, and the crude product content is> 95%.

[0073] Comparative Example 2

[0074] Comparative Example 2 provides a method for preparing glucuronide. The difference from Example 2 is that during the cooling crystallization in Comparative Example 2, the cooling rate is 20°C / h and the crystallization termination temperature is 10°C.

[0075] The purity of the glucuron-lactone obtained in Comparative Example 2 was 93.5%, the crystallization yield was 78.2%, and the crystal particle size was 100 mesh.

[0076] After the lactonization reaction is completed, the glucuron lactone crystals obtained by cooling and crystallizing the reaction product are uneven in size and poor in appearance, which is not conducive to storage.

[0077] Comparative Example 3

[0078] Comparative Example 3 provides a method for preparing glucuronolactone, which is different from Example 2 in that the solid content of the glucuronic acid concentrate after the glucuronic acid is concentrated in Comparative Example 3 is 40wt%, and other conditions remain unchanged.

[0079] The purity of the glucuron-lactone obtained in Comparative Example 3 was 92.7%, the crystallization yield was 12.2%, and the crystal particle size was 50 mesh.

[0080] Since the solid content of the glucuronic acid concentrate is low, the glucuronic acid concentration in the reaction system is low and the crystallization rate is not high.

[0081] Test Case

[0082] Test Example 1

[0083] Test Example 1: Liquid chromatography test was performed on the glucuronolactone crystals prepared in Example 2, and the test conditions were:

[0084] Mobile phase: 10mmol / L formic acid aqueous solution;

[0085] Chromatographic column: calcium column (300*7.7 or similar column);

[0086] Flow rate: 0.5 mL / min;

[0087] Column temperature: 55°C;

[0088] Detector temperature: 45°C;

[0089] Standard concentration: 1.0 mg / mL; the standard is selected from the China Food and Drug Inspection Institute, D-glucuronolactone, CAS No. 32449-92-6, calculated as C6H8O6, the content is 99.9%;

[0090] Test sample concentration: 1.0 mg / mL;

[0091] Chromatographic conditions: run with 100% 10 mmol / L formic acid aqueous solution for 30 min.

[0092] Test results such as Figure 1 As shown. Figure 1 It can be seen that the 16.383min peak is the glucuron lactone peak, and the 24min peak is the system peak, and the glucuron lactone content is 98.5%.

[0093] For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here, and the obvious changes or modifications derived from them are still within the scope of protection of the claims of the invention.

Claims

1. A method for preparing glucuronolactone, characterized in that: The following steps are involved: Adding whole bacteria containing inositol oxidase to an inositol feed liquid for conversion, filtering the conversion liquid to obtain a filtrate, desalting, decolorizing and concentrating the filtrate to obtain a concentrated solution, wherein the concentrated solution has a solid content of 50-70w%; wherein the inositol content in the inositol feed liquid is 1-10wt%, the conversion temperature is 30-40°C, the conversion pH is 8.0-9.0, and the conversion time is 8-12h; Lactic acid is added to the concentrated solution for lactonization reaction, the reaction product is concentrated, dynamic gradient crystallization is performed at a cooling rate of 5-10°C / h and a crystallization termination temperature of 5-15°C, and the product is filtered, washed and dried to obtain a glucuron lactone product, wherein the amount of lactic acid added is 0.5-3.0 times the volume of the concentrated solution, the lactonization reaction temperature is 50-70°C, and the reaction time is 3-6h.

2. The method for preparing glucuronolactone according to claim 1, characterized in that: The conversion liquid is filtered to obtain a filtrate comprising: The conversion liquid is filtered through a ceramic membrane to obtain a ceramic membrane filtrate, and the ceramic membrane filtrate is filtered through an ultrafiltration membrane assembly to collect a filtrate.

3. A method for preparing glucuronolactone according to claim 2, characterized in that: The pore size of the ceramic membrane is 20-100 nm; and / or the pore size of the ultrafiltration membrane used in the ultrafiltration membrane assembly is 5000-20000 Da.

4. The method for preparing glucuronolactone according to claim 3, characterized in that: The filtrate is desalted, decolorized and concentrated to obtain a concentrate comprising: The filtrate is desalted by a cation exchange resin to obtain a desalted liquid; The desalted liquid is decolorized by adsorption by a macroporous resin to obtain a decolorized liquid; The decolorized liquid is concentrated by a nanofiltration membrane assembly to obtain a nanofiltration concentrate; The nanofiltration concentrate is concentrated in a concentrator to obtain the concentrate.

5. A method for preparing glucuronolactone according to claim 4, characterized in that: The cation exchange resin is a strongly acidic cation exchange resin; The conductivity of the desalted solution is <7000us / cm; The nanofiltration membrane pore size used in the nanofiltration membrane assembly is 150-300Da, the solid content of the nanofiltration concentrate is 10-15wt%, and the glucuronic acid content is 50-150g / L.

6. The method for preparing glucuronolactone according to claim 1, characterized in that: The reaction product is concentrated and comprises: The reaction product is concentrated under vacuum, the vacuum concentration temperature is 50-70° C., the vacuum degree is <-0.09 MPa, and the volume of the distilled water is 30-50% of the volume of the concentrated liquid.

Images