Phytase microspheres, preparation method thereof and method for co-producing inositol and monopotassium phosphate

Abstract

The invention discloses a phytase microsphere and a preparation method thereof. According to the phytase microsphere, phytase is embedded in a polymer microsphere; the preparation method comprises the following steps: firstly, preparing a polymer solution, adding a phytase solution into the polymer solution, dropwise adding the obtained mixed solution into an inorganic salt stationary solution, reacting to generate microspheres, adding the microspheres into a cross-linking solution, and carrying out cross-linking reaction to finally obtain the phytase microspheres. The embedding rate of the phytase in the prepared phytase microspheres is 65-85%, the porosity of the phytase microspheres is 30-50%, the activity of the phytase is high, and the phytase can be reused due to the existence of the microsphere carrier. The invention further comprises a method for co-producing inositol and monopotassium phosphate, the phytase microspheres and a potassium phytate solution are subjected to a hydrolysis reaction to obtain hydrolysate, the hydrolysate is separated through simulated moving bed chromatography, and an inositol phase and a monopotassium phosphate phase are obtained; the phytase microspheres have the characteristics of high activity and reusability, so that continuous hydrolysis of potassium phytate is realized.

Description

Technical Field

[0001] The invention relates to the technical field of inositol preparation, in particular to a phytase microsphere and a preparation method thereof and a method for co-producing inositol and potassium dihydrogen phosphate. Background Art

[0002] Inositol, chemically known as cyclohexanehexol, is an important vitamin required by higher animals. Inositol can promote fat metabolism and reduce the cholesterol content in the blood. It is also used as an anti-fatty liver drug for the treatment of cirrhosis, hepatitis, high cholesterol, excessive fat and vascular sclerosis. In addition to being used directly as a drug (such as inositol tablets, hepatol, liver-soothing tablets, etc.), inositol can also be used as a pharmaceutical intermediate to make many drugs, such as nicotinic acid inositol ester, pulsetong, anticancer drug paclitaxel, etc.

[0003] Potassium dihydrogen phosphate is used as a buffer and culture agent in industry; it is used as a high-efficiency phosphorus-potassium compound fertilizer in agriculture. It is widely applicable to various types of economic crops, such as grain, fruits, vegetables, etc. It has many excellent effects such as significantly increasing production and income, improving quantity / optimizing quality, resisting lodging, resisting diseases and pests, and preventing premature aging. It also has the effect of overcoming nutritional deficiencies caused by the aging of the root system and the decreased absorption capacity in the later stages of crop growth.

[0004] Potassium phytate can be prepared from corn soaking water, and inositol and potassium dihydrogen phosphate can be obtained by hydrolyzing potassium phytate. The hydrolysis process of potassium phytate in the prior art mainly includes two methods: high temperature and high pressure hydrolysis and phytase hydrolysis. Among them, high temperature and high pressure hydrolysis equipment has large investment, high energy consumption, poor production environment, and low production efficiency; phytase hydrolysis method is widely used because it does not have the above disadvantages. However, the phytase hydrolysis method has the problem that it cannot be recovered and reused after the hydrolysis is completed, resulting in a waste of enzymes and high costs.

[0005] Document CN101492665A discloses a kind of immobilized cross-linked enzyme aggregate and its preparation method, and this cross-linked enzyme aggregate is fixed on porous microsphere carrier, and described preparation method comprises: first let the free enzyme that needs to be fixed be dispersed in porous microsphere; Then carry out precipitation and cross-linking of enzyme protein in porous microsphere successively, finally rinse porous microsphere, and obtain cross-linked enzyme aggregate. The cross-linked enzyme aggregate prepared by the above method has certain physical form and stable structure, can be recovered and reused, and can be used for continuous production in industrialized production. However, in the above technology, cross-linked enzyme aggregate is to prepare enzyme aggregate by cross-linking method, and is assisted by carrier for recovery, and needs to add precipitation agent to carry out enzyme precipitation in the method, and easily causes the loss of enzyme activity in precipitation process, so that the proportion of active enzyme in cross-linked enzyme aggregate is greatly reduced. Summary of the invention

[0006] In view of this, the object of the present invention is to provide a phytase microsphere and a preparation method thereof and a method for co-producing inositol and potassium dihydrogen phosphate, which overcome the technical problem of low phytase activity in the prior art.

[0007] In order to achieve the above object, the present invention provides a phytase microsphere, wherein the microsphere is a polymer microsphere that encapsulates phytase;

[0008] The embedding rate of the phytase is 65-85%, and the porosity of the polymer microspheres is 30-50%.

[0009] The present invention also includes a method for preparing the above-mentioned phytase microspheres, comprising the following steps:

[0010] Add the polymer into water and heat to 80-100°C to dissolve the polymer to obtain a polymer solution;

[0011] After cooling the polymer solution to 60-80° C., adding a phytase solution thereto to obtain a mixed solution;

[0012] adding the mixed solution dropwise to an inorganic salt fixing solution to generate microspheres;

[0013] The microspheres are filtered and then washed, and the washed microspheres are added into a cross-linking solution, and filtered after the cross-linking reaction to obtain phytase microspheres.

[0014] The phytase microspheres provided by the present invention embed phytase with polymer microspheres; the present invention fixes phytase in an embedded form, and the embedding rate can reach 65-85%. In the phytase microspheres prepared by the embedding method, the phytase is surrounded by the microspheres, and the porosity is 30-50%, which can prevent the enzyme from leaking out, and the enzyme molecules themselves do not undergo physical and chemical changes, and the high-level structure changes are less, ensuring that the enzyme maintains a high activity. The preparation method of the phytase microspheres of the present invention is simple, easy to operate, and has low cost. The prepared phytase microspheres have high activity and can be reused.

[0015] In addition, the present invention also includes a method for co-producing inositol and potassium dihydrogen phosphate, wherein the phytase microspheres and potassium phytate solution are subjected to a hydrolysis reaction at 50-60° C. to obtain a hydrolyzate.

[0016] The hydrolyzate is separated by simulated moving bed chromatography to obtain an inositol phase and a potassium dihydrogen phosphate phase.

[0017] The invention provides a method for co-producing inositol and potassium dihydrogen phosphate. The phytase microspheres of the invention are used to carry out a hydrolysis reaction with a potassium phytate solution. Since the phytase is fixed in the microspheres, the potassium phytate solution can be continuously fed during the hydrolysis process, thereby realizing continuous hydrolysis of the potassium phytate. The phytase activity in the phytase microspheres is high, thereby realizing rapid hydrolysis of the potassium phytate. Furthermore, the enzyme activity will not be significantly reduced as the hydrolysis proceeds, thereby having good long-term effectiveness, thereby realizing continuous hydrolysis of the potassium phytate. DETAILED DESCRIPTION

[0018] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0019] The invention provides a phytase microsphere, wherein the microsphere is a polymer microsphere that embeds the phytase.

[0020] In the present invention, the embedding rate of the phytase can reach 65-85%; in the present invention, the embedding rate of the phytase = (actual amount of phytase contained ÷ theoretical maximum inclusion amount) × 100%; wherein, the units of the actual amount of phytase contained and the theoretical maximum inclusion amount need to be consistent. Generally speaking, it is difficult to achieve an embedding rate of 100% in actual production. The higher the embedding rate, the more effective ingredients (enzymes) contained in the microspheres, and the better the effect of the microspheres. In addition, the porosity of the polymer microspheres can reach 30-50%. At this porosity, the proportion of active phytase to the total amount of phytase in the phytase microspheres can be as high as 65-75%, which is suitable for substrates or reactants to contact the enzyme through pores to achieve the best reaction rate. The porosity of the polymer microspheres is preferably 30-40%. At this porosity, the phytase exudation can be further reduced, and while ensuring the activity of the phytase, the embedding rate of the phytase in the phytase microspheres can be further improved. More preferably, it is 30%-35%. Under this porosity, the phytase activity and the embedding rate of phytase in the phytase microspheres can reach an optimal balance, and the phytase embedding rate can be 80%-85%, and the activity also reaches an optimal 70%-75%. In the present invention, the enzyme activity in the phytase microspheres is greatly improved by the embedding method. It can be seen that the loss of enzyme activity is less affected when the phytase microspheres are prepared by the embedding method, and the prepared phytase microspheres have higher activity.

[0021] In the present invention, the polymer in the polymer microspheres is preferably a natural polysaccharide polymer; further, the natural polysaccharide polymer includes carrageenan, chitosan or sodium alginate; further, the carrageenan is preferably K (Kappa) type carrageenan, and the gel that K type carrageenan can form with potassium ions has a higher strength, so the generated microspheres have a certain porosity and a higher strength.

[0022] The present invention also includes a method for preparing the above-mentioned phytase microspheres, comprising the following steps:

[0023] Add the polymer into water and heat to 80-100°C to dissolve the polymer to obtain a polymer solution;

[0024] After cooling the polymer solution to 60-80° C., adding a phytase solution thereto to obtain a mixed solution;

[0025] adding the mixed solution dropwise to an inorganic salt fixing solution to generate microspheres;

[0026] The microspheres are filtered and then washed, and the washed microspheres are added into a cross-linking solution, and filtered after the cross-linking reaction to obtain phytase microspheres.

[0027] The present invention first adds the polymer into water, heats it to 80-100°C to dissolve it, and obtains a polymer solution. In the present invention, the mass ratio of the polymer to water is preferably 1:(20-30); the present invention has no special restrictions on the water, for example, distilled water or purified water can be used. The present invention has no special restrictions on the heating method and equipment. In the present invention, the dissolution is preferably carried out under stirring conditions, and the stirring rate is preferably 20-100rpm.

[0028] After obtaining the polymer solution, the present invention cools the polymer solution to 60-80° C., and then adds a phytase solution thereto to obtain a mixed solution. The present invention has no particular limitation on the cooling, and for example, natural cooling at room temperature can be adopted. In the present invention, the concentration of the phytase solution is preferably 50,000-100,000 units / ml. In the present invention, the volume ratio of the phytase solution to the polymer solution is 1:(1-3).

[0029] After obtaining the mixed solution, the present invention drips the mixed solution into the inorganic salt fixed solution to generate microspheres. In the present invention, the inorganic salt fixed solution is preferably a KH2PO4 solution with a concentration of 3-5wt%, a KCl solution with a concentration of 3-5wt%, or a CaCl2 solution with a concentration of 3-5wt%. In the present invention, the mixed solution is preferably added dropwise, and a microsphere can be generated after each drop of the mixed solution is added to the inorganic salt fixed solution; the diameter of the microsphere can be 1-3mm. The present invention has no special limitation on the dripping rate. In the present invention, after the dripping is completed, the reaction is preferably carried out for 3-5h.

[0030] After the microspheres are generated, the present invention filters the microspheres and then washes them, adds the washed microspheres to a cross-linking solution, and filters them after the cross-linking reaction to obtain phytase microspheres. In the present invention, the filtration is preferably carried out using a filter membrane with a pore size of 20-40 mesh, and the filter membrane is preferably a nylon woven mesh. In the present invention, the washing is preferably carried out using water, and the present invention has no special restrictions on the type of water, such as purified water or distilled water. In the present invention, the cross-linking solution is preferably a short-chain aldehyde solution; more preferably, the short-chain aldehyde solution is a glutaraldehyde solution or a formaldehyde solution; the concentration of the glutaraldehyde solution is 20-30% (w / v), and the concentration of the formaldehyde solution is 20-30% (w / v); the present invention has no special restrictions on the dosage ratio of the microspheres to the cross-linking solution, and it is advisable to use an excess of the cross-linking solution; the cross-linking reaction of the present invention is a reaction between a polymer and a cross-linking solution, and the purpose is to further increase the strength of the microspheres and reduce the breakage rate of the microspheres, which is significantly different from the prior art of preparing microspheres by enzyme precipitation. In the present invention, the temperature of the cross-linking reaction is preferably 20-40° C., and the time is preferably 2-3 hours.

[0031] The present invention also includes a method for co-producing inositol and potassium dihydrogen phosphate, comprising: hydrolyzing the phytase microspheres and potassium phytate solution at 50-60° C. to obtain a hydrolyzate;

[0032] The hydrolyzate is separated by simulated moving bed chromatography to obtain an inositol phase and a potassium dihydrogen phosphate phase.

[0033] The present invention firstly hydrolyzes the phytase microspheres with a potassium phytate solution at 50-60° C. to obtain a hydrolyzate. In the present invention, the solid content of the potassium phytate solution is preferably 20-30wt%, and the pH is preferably 4-6. In the present invention, the hydrolysis reaction is preferably carried out at 50-60° C. under the condition of contacting the phytase microspheres with the potassium phytate solution, and the reaction time is preferably 4-6h.

[0034] In a preferred embodiment, the phytase microspheres are preferably loaded in a reaction column, and the potassium phytate solution is hydrolyzed in the form of being fed into the reaction column. In this embodiment, the reaction column is preferably a stainless steel column, the column bed volume is preferably 5-50L, and the diameter-to-height ratio is preferably (3-5): 1; the loading amount of the phytase microspheres is preferably 70-90% of the volume of the stainless steel column, and the loading method is preferably natural loading; the reaction column is preferably multi-column series connection, and when multi-column series connection is adopted, the reaction solution stays in all columns for 4-6h; the feed rate of the potassium phytate solution is preferably 0.2-1BV / h. The method comprises the following steps: loading phytase microspheres into a reaction column and introducing a potassium phytate solution into the column for hydrolysis reaction. The potassium phytate solution is continuously fed into the reaction column, undergoes a hydrolysis reaction with the phytase in the phytase microspheres in the column, and then the hydrolyzate flows out from the other end. During this process, the temperature, pH and other conditions are kept stable, and the phytase will not be denatured. Therefore, continuous feeding and continuous reaction can be performed without replacing the phytase in batches, thereby achieving continuous hydrolysis of potassium phytate.

[0035] After obtaining the hydrolyzate, the present invention separates the hydrolyzate by simulated moving bed chromatography to obtain an inositol phase and a potassium dihydrogen phosphate phase. In the present invention, the operating temperature of the simulated moving bed chromatography is preferably 55-65°C; the stationary phase is preferably a chelating cationic resin, the functional group of the chelating cationic resin is preferably aminophosphonic acid, and the skeleton is preferably polystyrene; the volume ratio of the stationary phase to the single feed of the hydrolyzate is preferably (8-10):1; the mobile phase is purified water, and the present invention has no special restrictions on the type of water, such as distilled water or purified water; the volume ratio of the mobile phase to the hydrolyzate is preferably (2-3):1.

[0036] 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.

[0037] Example 1

[0038] S1. Add 500 g of carrageenan to 15 L of water, heat to 90 ° C, and dissolve under stirring at 100 rpm to obtain a carrageenan solution;

[0039] S2. After cooling the carrageenan solution to 60° C., 5 L of phytase solution (concentration 80,000 units / ml) was added thereto to obtain a mixed solution;

[0040] S3. 20 L of the mixed solution was added dropwise to 100 L of KH2PO4 solution (concentration 5 wt%), and the microspheres were generated after reacting for 4 h;

[0041] S4. The microspheres were filtered through a 40-mesh nylon woven net and then washed. The washed microspheres were added to 100 L of glutaraldehyde solution (concentration of 20% (w / v)), cross-linked at 40° C. for 2 h, and then filtered to obtain 19.6 kg of phytase microspheres.

[0042] The phytase embedding rate of the phytase microspheres obtained in this example is 80%, the diameter is 3 mm, the porosity of the phytase microspheres is 30%, and the active phytase accounts for 75% of the total amount of phytase.

[0043] Example 2

[0044] S1. Add 500 g of chitosan to 10 L of water, heat to 80 ° C, and dissolve under stirring at 20 rpm to obtain a chitosan solution;

[0045] S2. After the chitosan solution was cooled to 80°C, 5 L of phytase solution (concentration 50,000 units / ml) was added thereto to obtain a mixed solution;

[0046] S3. 15 L of the mixture was added dropwise to 100 L CaCl2 solution (concentration 4 wt%), and 14.9 kg of microspheres were generated after 5 h of reaction;

[0047] S4. The microspheres were filtered through a 30-mesh nylon woven net and washed, and the washed microspheres were added to 100 L of glutaraldehyde solution (concentration of 25% (w / v)), and the cross-linking reaction was carried out at 20° C. for 2.5 hours and then filtered to obtain 14.7 kg of phytase microspheres.

[0048] The phytase embedding rate of the phytase microspheres obtained in this example is 85%, the diameter is 2 mm, the porosity of the phytase microspheres is 40%, and the active phytase accounts for 70% of the total amount of phytase.

[0049] Example 3

[0050] S1. Add 500 g of sodium alginate to 12.5 L of water, heat to 100 ° C, and dissolve under stirring at 80 rpm to obtain a sodium alginate solution;

[0051] S2. After the sodium alginate solution was cooled to 70°C, 12.5 L of phytase solution (concentration 100,000 units / ml) was added thereto to obtain a mixed solution;

[0052] S3. 25 L of the mixture was added dropwise to 200 L CaCl2 solution (concentration 3 wt%), and 24.5 kg of microspheres were generated after reacting for 3 h;

[0053] S4. The microspheres were filtered through a 20-mesh nylon woven mesh and then washed. The washed microspheres were added to 200 L of formaldehyde solution (concentration of 30% (w / v)), cross-linked at 30° C. for 3 h and then filtered to obtain 24 kg of phytase microspheres.

[0054] The phytase embedding rate of the phytase microspheres obtained in this example is 65%, the diameter is 1 mm, the porosity of the phytase microspheres is 50%, and the active phytase accounts for 60% of the total amount of phytase.

[0055] Example 4

[0056] S1. The phytase microspheres obtained in Example 1 are naturally loaded into a stainless steel reaction column (the column bed volume is preferably 20 L, the diameter-to-height ratio is preferably 3:1, and the loading amount is 80% of the reaction column volume), and 80 L of potassium phytate solution (temperature of 60° C., pH of 4, solid content of 20 wt%) is fed into the stainless steel reaction column at a feed rate of 4 L / h to obtain 80 L of hydrolyzate;

[0057] S2. the hydrolyzate was fed to a simulated moving bed chromatography (temperature of 65° C., 60 L of chelating cationic resin as stationary phase, and 120 L of purified water as mobile phase), and 145 kg of potassium dihydrogen phosphate phase (potassium dihydrogen phosphate content of 14.1%) and 65 kg of inositol phase (inositol content of 6.9%) were separated.

[0058] Example 5

[0059] S1. The phytase microspheres obtained in Example 2 are naturally loaded into a stainless steel reaction column (the column bed volume is preferably 5L*3 in series, the diameter-to-height ratio is preferably 4:1, and the loading amount is 90% of the reaction column volume), and 80L of potassium phytate solution (temperature of 50°C, pH of 5, solid content of 30wt%) is fed into the stainless steel reaction column at a feed rate of 3L / h to obtain 80L of hydrolyzate;

[0060] S2. the hydrolyzate was fed to a simulated moving bed chromatography (temperature of 55° C., 60 L of chelating cationic resin as stationary phase, and 240 L of purified water as mobile phase), and 220 kg of potassium dihydrogen phosphate phase (potassium dihydrogen phosphate content of 13.1%) and 115 kg of inositol phase (inositol content of 5.6%) were separated.

[0061] Example 6

[0062] S1. The phytase microspheres obtained in Example 3 are naturally filled into a stainless steel reaction column (the column bed volume is preferably 6L*4 in series, the diameter-to-height ratio is preferably 5:1, and the filling amount is 70% of the reaction column volume), and 150L of potassium phytate solution (temperature of 55°C, pH of 6, solid content of 25wt%) is fed into the stainless steel reaction column at a feed rate of 6L / h to obtain 150L of hydrolyzate;

[0063] S2. the hydrolyzate was fed to a simulated moving bed chromatography (temperature of 60° C., 60 L of chelated cationic resin as stationary phase, and 400 L of purified water as mobile phase), and 350 kg of potassium dihydrogen phosphate phase (potassium dihydrogen phosphate content of 13.0%) and 220 kg of inositol phase (inositol content of 4.6%) were separated.

[0064] Comparative Example 1

[0065] The phytase microspheres in step S1 of Example 6 were replaced by an equal amount of cross-linked enzyme aggregates (the enzyme therein was phytase, and the preparation method of the aggregates was prepared according to the method of Example 1 in the prior art CN101492665A (replacing the organophosphorus degrading enzyme therein with phytase)), and other conditions remained unchanged.

[0066] The porosity of the cross-linked enzyme aggregate prepared in the prior art is 12%, and the active phytase accounts for 51% of the total amount of phytase.

[0067] Finally, 350 kg of potassium dihydrogen phosphate phase (potassium dihydrogen phosphate content 9.7%) and 220 kg of inositol phase (inositol content 3.45%) were obtained.

[0068] Comparative Example 2

[0069] The CaCl2 solution in step S3 of Example 2 was replaced by an equal amount of a CaCl2 solution having a concentration of 6%, and other conditions remained unchanged.

[0070] The embedding rate of phytase in the phytase microspheres obtained in this comparative example is 72%, the diameter is 2 mm, the porosity of the phytase microspheres is 30%, and the active phytase accounts for 55% of the total amount of phytase.

[0071] Comparative Example 3

[0072] The amount of sodium alginate in step S1 of Example 3 was replaced with 1000 g, and other conditions remained unchanged.

[0073] The phytase embedding rate of the phytase microspheres obtained in this comparative example is 70%, the diameter is 1.5 mm, the porosity of the phytase microspheres is 35%, and the active phytase accounts for 50% of the total amount of phytase.

[0074] Comparative Example 4

[0075] The formaldehyde solution (concentration of 30% (w / v)) in step S4 of Example 3 was replaced by formaldehyde solution (concentration of 50% (w / v)), and other conditions remained unchanged.

[0076] The embedding rate of phytase in the phytase microspheres obtained in this comparative example is 75%, the diameter is 2.5 mm, the porosity of the phytase microspheres is 20%, and the active phytase accounts for 45% of the total amount of phytase.

[0077] Test Case

[0078] A. Determination of porosity: The porosity in the above embodiments and comparative examples was determined by the gas adsorption method specified in the GB / T21650.2-2008 detection method.

[0079] B. Determination of the proportion of active phytase: Detect phytase activity according to the GB / T18634-2009 detection method. (phytase microsphere enzyme activity U / g*phytase microsphere weight g) / (phytase enzyme activity U / ml*phytase volume ml)

[0080] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention is 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 replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A phytase microsphere, It is characterized in that Phytase is embedded in polymer microspheres; wherein the embedding rate of the phytase is 65-85%, and the porosity of the polymer microspheres is 30-50%.

2. The phytase microspheres according to claim 1, It is characterized in that The active phytase in the phytase microspheres accounts for 65-75% of the total phytase.

3. The phytase microspheres according to claim 1, It is characterized in that The polymer in the polymer microspheres is a natural polysaccharide polymer.

4. The phytase microspheres according to claim 3, It is characterized in that The natural polysaccharide polymer includes carrageenan, chitosan or sodium alginate.

5. A method for preparing phytase microspheres, applied to the phytase microspheres according to any one of claims 1 to 4, It is characterized in that The following steps are involved: Add the polymer into water and heat to 80-100°C to dissolve the polymer to obtain a polymer solution; After cooling the polymer solution to 60-80° C., adding a phytase solution thereto to obtain a mixed solution; adding the mixed solution dropwise to an inorganic salt fixing solution to generate microspheres; The microspheres are filtered and then washed, and the washed microspheres are added into a cross-linking solution, and filtered after the cross-linking reaction to obtain phytase microspheres.

6. The method according to claim 5, It is characterized in that In the polymer solution, the mass ratio of the polymer to water is 1:(20-30).

7. The method according to claim 5, It is characterized in that The concentration of the phytase solution is 50,000-100,000 units / ml, and the volume ratio of the phytase solution to the polymer solution is 1:(1-3).

8. The method according to claim 5, It is characterized in that The inorganic salt fixing liquid is KH 2 PO 4 solution, 3-5wt% KCl solution or 3-5wt% CaCl 2 solution; and / or, After the dropwise addition is completed, the reaction is carried out for 3-5 hours.

9. The method according to claim 5, It is characterized in that The cross-linking solution is a short-chain aldehyde solution; The short-chain aldehyde solution is a glutaraldehyde solution or a formaldehyde solution, the concentration of the glutaraldehyde solution is 20-30% (w / v), and the concentration of the formaldehyde solution is 20-30% (w / v); and / or, The cross-linking reaction is carried out at a temperature of 20-40°C and for a time of 2-3 hours.

10. A method for co-producing inositol and potassium dihydrogen phosphate, It is characterized in that Using the phytase microspheres according to any one of claims 1 to 4 and potassium phytate solution, at 50-60° C., to carry out a hydrolysis reaction to obtain a hydrolyzate. The hydrolyzate is separated by simulated moving bed chromatography to obtain an inositol phase and a potassium dihydrogen phosphate phase.