Method for producing immobilized glucose isomerase through extrusion granulation

Abstract

The invention belongs to the technical field of biology, and particularly relates to a method for producing immobilized glucose isomerase based on extrusion granulation. The preparation method comprises the following steps: firstly, uniformly mixing an enzyme solution with inorganic active silica powder and sodium alginate powder by using an inorganic carrier as a granulation main body frame, strongly mixing to enable enzyme to be adsorbed inside and on the surface of the carrier, and carrying out an extrusion granulation technology to obtain granular immobilized glucose isomerase; sodium alginate is subjected to cross-linking solidification under the cross-linking solidification effect of a cross-linking agent solution, and enzyme is immobilized and embedded in the carrier, so that the mechanical strength and crushing hardness of the immobilized enzyme are ensured. The immobilized enzyme particles prepared through the method have excellent rigidity, stability and water resistance, the particle strength is basically not changed after the immobilized enzyme particles are soaked in water for 3 months, and the problem that the immobilized enzyme particles are broken due to the fact that the particle loading capacity is too large and the immobilized enzyme particles are soaked in water for a long time in the industrial production process can be solved. In the repeated use process of the immobilized particles, the catalytic activity can be maintained at 80% of the initial state, and industrial continuous production is facilitated.

Description

Technical Field

[0001] The invention belongs to the field of biotechnology, and in particular relates to a method for producing immobilized glucose isomerase based on extrusion granulation. Background Art

[0002] High fructose corn syrup (HFCS) is a mixed syrup composed of glucose and fructose, which is made from corn starch through liquefaction, saccharification and isomerization. More than 30% of the sweeteners on the market are made from fructose syrup. High fructose corn syrup has a pure taste and rich nutrition. It greatly guarantees the nutrition and flavor of food without changing people's dietary structure.

[0003] The most critical technology in the production and processing of high fructose syrup is the isomerization of glucose. The isomerization process of glucose isomerase is a thermodynamic equilibrium reaction. As the isomerization temperature increases, the isomerization reaction will be promoted to the direction of fructose. At high temperatures, the heat-resistant glucose isomerase catalyzes glucose to directly generate HFCS-55, which is the mainstream product on the market. High fructose syrup mainly includes three types: HFCS-42, HFCS-55, and HFCS-90. Only HFCS-42 can be directly produced, while HFCS-90 and HFCS-55 require further concentration, purification, and blending before production. It can be seen that glucose isomerase is still a major problem in domestic production technology and stable promotion.

[0004] The methods for immobilizing glucose isomerase can be divided into cross-linking, adsorption, covalent bonding and embedding. Only the cross-linking and embedding methods are suitable for industrial production and have higher efficiency. Of course, the four methods are not used independently. In most cases, several methods are used in series to achieve the best immobilization effect and industrial production efficiency. The commercial products that currently occupy the global market are mainly Novozymes' T and Genenco IGI, these two products still dominate the glucose isomerase market, and the production process of these two products uses a series combination of cross-linking and adsorption methods.

[0005] The choice of carrier and immobilization method are two key issues in the process of glucose isomerase immobilization. The structure and characteristics of the carrier can directly affect the performance of the immobilized enzyme. The patents currently disclosed in the market use single carriers such as natural porous materials, magnetic microspheres, and synthetic resins for immobilization, which have certain effects, but the process is relatively complicated, and there are still certain problems in carrier synthesis and recovery. In addition, organic residues and food fields are also issues that need to be considered.

[0006] Therefore, the development of immobilized enzymes with excellent mechanical strength and meeting the green requirements of food is a hot topic and difficulty in the current industrial research of immobilized glucose isomerase. Summary of the invention

[0007] In view of this, in view of the problems currently faced by the industrial production of immobilized enzymes, the present invention discloses a method for producing immobilized glucose isomerase based on extrusion granulation, which is an immobilized enzyme synthesis route with simple process, low raw material cost, green and harmless, and high mechanical strength of the product.

[0008] Furthermore, the present invention discloses a method for producing immobilized glucose isomerase based on extrusion granulation, aiming to solve the problem of insufficient mechanical strength of immobilized glucose isomerase in the industrial production process, and the problem of breakage and disintegration caused by soaking in water for a long time. The immobilized enzyme synthesis method disclosed in the present invention can not only solve the problem of food safety and hygiene caused by residual organic monomers in the current immobilized enzyme synthesis process, but also solve the problems of complex preparation process of carrier materials used in the current immobilized enzyme synthesis process and high raw material cost.

[0009] In order to achieve the above object, the present invention adopts the following technical solution:

[0010] A method for producing immobilized glucose isomerase based on extrusion granulation, the synthesis method comprising the following steps:

[0011] S1: Mixing of carrier and enzyme solution: The inorganic carrier and sodium alginate powder are mixed in a drum mixer at a mass ratio of 1:0.5 to 1:2 to obtain a mixed carrier, and the enzyme solution is slowly added at a mass ratio of the mixed carrier to the enzyme solution of 1.3:1 to 2:1, and the mixture is continuously stirred until uniform to form powdered enzyme particles.

[0012] Furthermore, the inorganic carrier is active silicon micropowder, diatomaceous earth or bentonite, preferably active silicon micropowder.

[0013] Furthermore, the particle size of the inorganic carrier is 1000-2500 mesh, preferably 1500-2500 mesh, and more preferably 2000-2300 mesh.

[0014] Furthermore, the particle size of the sodium alginate powder is 100-400 mesh, preferably 200-400 mesh, and more preferably 200-300 mesh.

[0015] Furthermore, the inorganic carrier is of food grade; the sodium alginate powder is of food grade.

[0016] S2: Extrusion granulation: The mixed powdered enzyme granules are extruded into granules through a screw extruder. During the extrusion process, water cooling is required to cool the outlet.

[0017] Furthermore, the screw extruder is a single screw extruder or a twin screw extruder, preferably a single screw extruder.

[0018] S3: Cross-linking and curing: 2% glutaraldehyde is added to the cross-linking agent solution, and the particles extruded from S2 are immersed in the cross-linking agent solution to form cured particles.

[0019] Furthermore, the cross-linking agent is calcium chloride solution, barium chloride solution or zinc sulfate solution, preferably calcium chloride solution or barium chloride solution, more preferably calcium chloride solution.

[0020] Furthermore, the concentration of the crosslinking agent solution is 2% to 7%, preferably 3% to 5%, more preferably 4% to 5%; the curing temperature is 4 to 30°C, preferably 10-30°C, more preferably 10-25°C.

[0021] Furthermore, the soaking time is 1-6 hours, preferably 2-5 hours, and more preferably 2-3 hours.

[0022] S4: The solidified particles are transferred to a fluidized bed dryer for drying at a temperature of 50-60°C for 5-15 hours.

[0023] S5: After the dried particles are sieved through a sieve, the products with appropriate particle size specifications are the immobilized glucose isomerase particles.

[0024] Furthermore, the target particle size is 0.5-5 mm, preferably 0.5-3 mm, and more preferably 1-2 mm.

[0025] It should be noted that the present invention uses inorganic active silicon micropowder and sodium alginate as carriers, mixes them evenly, then adds glucose isomerase liquid, mixes and stirs evenly, and obtains powdered enzyme particles; after extrusion granulation, the particles change from powder to columnar, the internal structure is compacted, and after extrusion granulation, the particles are regular and uniform in size; after extrusion, the particles are cross-linked and solidified by a cross-linking agent solution, and then dried in a fluidized bed to obtain immobilized glucose isomerase particles with high mechanical strength and good water resistance. Moreover, the immobilized glucose isomerase particles within this particle size range can achieve the best catalytic performance / effect.

[0026] Moreover, the technical principle of the present invention is as follows:

[0027] The present invention adopts the form of screw extrusion granulation to produce immobilized glucose isomerase, with inorganic materials and sodium alginate as carriers. The glucose isomerase liquid is well adsorbed and combined with the carrier after mixing, and is formed into uniform columnar particles after screw extrusion. High-strength cross-linked particles are formed under the action of a cross-linking agent, and the enzyme immobilization process is completed after drying.

[0028] Compared with the currently reported immobilized enzymes, the immobilized enzyme produced by the present invention has better stability, mechanical strength and water resistance, and can still maintain 80% catalytic activity under the condition of continuous catalytic production for three months, and the particle integrity is good, without obvious looseness. Compared with the current commercial products, it has the advantages of lower raw material cost, simpler process route, and easy industrialization.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The immobilized glucose isomerase production route disclosed in the present invention adopts single-screw extrusion granulation technology to produce the immobilized enzyme. The synthesized immobilized enzyme has a porous structure and uniform particle size, has a strong adsorption effect, and has a large specific surface area, which promotes the contact between the enzyme and the substrate, and helps to improve the enzyme-catalyzed reaction rate and the final conversion rate.

[0031] 2. The production route of immobilized glucose isomerase disclosed in the present invention uses food-grade inorganic carriers and food-grade sodium alginate as carriers, so that the immobilized enzyme fully meets the production standards in terms of food safety.

[0032] 3. The production route of immobilized glucose isomerase disclosed in the present invention uses sodium alginate as one of the carriers. After cross-linking with a cross-linking agent, the mechanical strength of the particles is greatly improved, thereby avoiding the risk of particle breakage leading to shortened life and reduced efficiency during the process of immobilized enzyme-catalyzed glucose isomerization.

[0033] 4. The production route of immobilized glucose isomerase disclosed in the present invention uses active silicon micropowder as one of the carriers. Due to its surface hydrophobic modification, it can improve the water resistance of the granular product and improve the stability of the immobilized enzyme.

[0034] 5. The immobilized glucose isomerase production route disclosed in the present invention can be used not only to produce immobilized glucose isomerase, but also to produce other enzymes, such as amylase, lipase, etc., and can realize large-scale industrial production of immobilized enzymes. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0036] Figure 1 This is a graph showing the relationship between the conversion rate and time of the process of catalyzing glucose into D-fructose in Example 2 of the present invention.

[0037] Figure 21 is a graph showing the relationship between the number of times the immobilized enzyme is reused and the conversion rate in Example 2 of the present invention. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] The word "embodiment" used here as an "exemplary" does not necessarily mean that any embodiment described is superior to or better than other embodiments. Unless otherwise specified, the performance index tests in the embodiments of this application are performed using conventional test methods in the art. It should be understood that the terms described in this application are only used to describe specific implementation methods and are not used to limit the content disclosed in this application.

[0040] Unless otherwise specified, the technical and scientific terms used in this document have the same meanings as commonly understood by ordinary technicians in the technical field to which this application belongs; other experimental methods and technical means not specifically specified in this application refer to experimental methods and technical means commonly used by ordinary technicians in this field.

[0041] In order to better illustrate the content of the present application, numerous specific details are provided in the specific examples below. It should be understood by those skilled in the art that the present application can also be implemented without certain specific details. In the embodiments, some methods, means, instruments, equipment, etc. well known to those skilled in the art are not described in detail in order to highlight the main purpose of the present application.

[0042] Under the premise of no conflict, the technical features disclosed in the embodiments of the present application can be combined arbitrarily, and the resulting technical solutions belong to the contents disclosed in the embodiments of the present application.

[0043] In order to better understand the present invention, the present invention is further specifically described below through the following examples, but it should not be understood as a limitation of the present invention. Some non-essential improvements and adjustments made by technicians in this field based on the above invention content are also considered to fall within the protection scope of the present invention.

[0044] Embodiment 1:

[0045] (1) Weigh 10 kg of active silicon micropowder (particle size 2000 mesh) and 6 kg of sodium alginate powder (particle size 300 mesh), mix them evenly with a drum mixer to obtain a mixed carrier; add 7.5 kg of the prepared enzyme solution with a concentration of 50%, continue to stir evenly, and form powder particles;

[0046] (2) slowly feeding the powdered particles obtained in step (1) into an extruder through a feed port of a single-screw extruder, with a screw speed of 1300 rpm, a rotary cutter speed of 300 rpm, a water cooling device turned on, and a material extrusion temperature not exceeding 50° C. The extruded material is pelletized by a cutter head to form columnar particles with a length of 1 mm and then shaken out;

[0047] (3) preparing a 5% calcium chloride solution and adding 2% glutaraldehyde, transferring the columnar particles extruded and cut in step (2) to the calcium chloride solution for immersion for 2 hours at a temperature of 15° C.;

[0048] (4) The soaked particles in step (3) are transferred to a fluidized bed for drying at a temperature of 50° C. for a drying time of 12 h. The dried particles are sieved to obtain the immobilized glucose isomerase particles with appropriate particle size specifications.

[0049] Verification of the catalytic performance of immobilized enzyme in glucose isomerization process:

[0050] In a 50 mL conical flask, 1.5 mL of 1 g / mL glucose solution, 4 mL of phosphate buffer (pH = 7.5), 0.5 mL of 0.061 g / mL magnesium sulfate solution and 2 mL of purified water were added, preheated in a 70 ° C shaker for 5 min, 0.5 g of the above-mentioned immobilized glucose isomerase was added, and catalytic conversion was carried out at 70 ° C, 230 rpm for 1 h.

[0051] Gas chromatography was used to analyze the component content of the product D-fructose. Chromatographic analysis showed that the conversion rate of this batch was 87.4%. After repeated recycling for ten times, the conversion rate was still able to maintain at around 81%.

[0052] Embodiment 2:

[0053] (1) Weigh 10 kg of active silicon micropowder (particle size 2000 mesh) and 6 kg of sodium alginate powder (particle size 300 mesh), mix them evenly with a drum mixer to obtain a mixed carrier; add 10 kg of the prepared enzyme solution with a concentration of 50%, continue to stir evenly, and form powder particles;

[0054] (2) slowly feeding the powdered particles obtained in step (1) into an extruder through a feed port of a single-screw extruder, with a screw speed of 1300 rpm, a rotary cutter speed of 300 rpm, a water cooling device turned on, and a material extrusion temperature not exceeding 50° C. The extruded material is pelletized by a cutter head to form columnar particles with a length of 1 mm and then shaken out;

[0055] (3) preparing a 5% calcium chloride solution and adding 2% glutaraldehyde, transferring the columnar particles extruded and cut in step (2) to the calcium chloride solution for immersion for 2 hours at a temperature of 15° C.;

[0056] (4) The soaked particles in step (3) are transferred to a fluidized bed for drying at a temperature of 50° C. for a drying time of 12 h. The dried particles are sieved to obtain the immobilized glucose isomerase particles with appropriate particle size specifications.

[0057] Verification of the catalytic performance of immobilized enzyme in glucose isomerization process:

[0058] In a 50 mL conical flask, 1.5 mL of 1 g / mL glucose solution, 4 mL of phosphate buffer (pH = 7.5), 0.5 mL of 0.061 g / mL magnesium sulfate solution and 2 mL of purified water were added, preheated in a 70 ° C shaker for 5 min, 0.5 g of the above-mentioned immobilized glucose isomerase was added, and catalytic conversion was carried out at 70 ° C, 230 rpm for 1 h.

[0059] The components of D-fructose were analyzed by gas chromatography. The results were statistically analyzed in the attached Figure 1 The conversion rate of this batch of products in catalyzing glucose to D-fructose for 1 hour reached 93.7%. Figure 2 It can be seen that after this batch of products is recycled ten times, the conversion rate can still be maintained at around 85%.

[0060] Embodiment 3:

[0061] (1) Weigh 10 kg of diatomaceous earth (particle size 2000 mesh) and 6 kg of sodium alginate powder (particle size 300 mesh), mix them evenly with a drum mixer to obtain a mixed carrier; add 10 kg of the prepared enzyme solution with a concentration of 50%, continue to stir evenly, and form powder particles;

[0062] (2) slowly feeding the powdered particles obtained in step (1) into an extruder through a feed port of a single-screw extruder, with a screw speed of 1300 rpm, a rotary cutter speed of 300 rpm, a water cooling device turned on, and a material extrusion temperature not exceeding 50° C. The extruded material is pelletized by a cutter head to form columnar particles with a length of 1 mm and then shaken out;

[0063] (3) preparing a 5% calcium chloride solution and adding 2% glutaraldehyde, transferring the columnar particles extruded and cut in step (2) to the calcium chloride solution for immersion for 2 hours at a temperature of 15° C.;

[0064] (4) The soaked particles in step (3) are transferred to a fluidized bed for drying at a temperature of 50° C. for a drying time of 12 h. The dried particles are sieved to obtain the immobilized glucose isomerase particles with appropriate particle size specifications.

[0065] Verification of the catalytic performance of immobilized enzyme in glucose isomerization process:

[0066] In a 50 mL conical flask, 1.5 mL of 1 g / mL glucose solution, 4 mL of phosphate buffer (pH = 7.5), 0.5 mL of 0.061 g / mL magnesium sulfate solution and 2 mL of purified water were added, preheated in a 70 ° C shaker for 5 min, 0.5 g of the above-mentioned immobilized glucose isomerase was added, and catalytic conversion was carried out at 70 ° C, 230 rpm for 1 h.

[0067] Gas chromatography was used to analyze the component content of the product D-fructose. Chromatographic analysis showed that the conversion rate of this batch was 90.3%. After repeated recycling for ten times, the conversion rate was still able to maintain at around 82%.

[0068] In order to further demonstrate the beneficial effects of the present invention and to better understand the present invention, the following comparative examples are used to further illustrate the technical features disclosed in the present invention, but they should not be understood as limiting the present invention. Other improvements made by those skilled in the art based on the above invention content without creative work are also considered to fall within the scope of protection of the present invention.

[0069] Comparative Example 1: Crosslinking without adding 2% glutaraldehyde

[0070] (1) Weigh 10 kg of active silicon micropowder (particle size 2000 mesh) and 6 kg of sodium alginate powder (particle size 300 mesh), mix them evenly with a drum mixer to obtain a mixed carrier; add 7.5 kg of the prepared enzyme solution with a concentration of 50%, continue to stir evenly, and form powder particles;

[0071] (2) slowly feeding the powdered particles obtained in step (1) into an extruder through a feed port of a single-screw extruder, with a screw speed of 1300 rpm, a rotary cutter speed of 300 rpm, a water cooling device turned on, and a material extrusion temperature not exceeding 50° C. The extruded material is pelletized by a cutter head to form columnar particles with a length of 1 mm and then shaken out;

[0072] (3) preparing a 5% calcium chloride solution, transferring the columnar particles extruded and cut in step (2) into the calcium chloride solution and soaking them for 2 hours at a temperature of 15° C.;

[0073] (4) The soaked particles in step (3) are transferred to a fluidized bed for drying at a temperature of 50° C. for a drying time of 12 h. The dried particles are sieved to obtain the immobilized glucose isomerase particles with appropriate particle size specifications.

[0074] Verification of the catalytic performance of immobilized enzyme in glucose isomerization process:

[0075] In a 50 mL conical flask, 1.5 mL of 1 g / mL glucose solution, 4 mL of phosphate buffer (pH = 7.5), 0.5 mL of 0.061 g / mL magnesium sulfate solution and 2 mL of purified water were added, preheated in a 70 ° C shaker for 5 min, 0.5 g of the above-mentioned immobilized glucose isomerase was added, and catalytic conversion was carried out at 70 ° C, 230 rpm for 1 h.

[0076] Gas chromatography was used to analyze the component content of the product D-fructose. Chromatographic analysis showed that the conversion rate of this batch was 84.2%. After repeated use for 10 times, the catalytic conversion rate was only 51.2%.

[0077] Comparative Example 2: No cross-linking and curing of the particles

[0078] (1) Weigh 10 kg of active silicon micropowder (particle size 2000 mesh) and 6 kg of sodium alginate powder (particle size 300 mesh), mix them evenly with a drum mixer to obtain a mixed carrier; add 7.5 kg of a prepared enzyme solution with a concentration of 50% and 2% glutaraldehyde, and continue to stir evenly to form powder particles;

[0079] (2) slowly feeding the powdered particles obtained in step (1) into an extruder through a feed port of a single-screw extruder, with a screw speed of 1300 rpm, a rotary cutter speed of 300 rpm, a water cooling device turned on, and a material extrusion temperature not exceeding 50° C. The extruded material is pelletized by a cutter head to form columnar particles with a length of 1 mm and then shaken out;

[0080] (3) The particles in step (2) are transferred to a fluidized bed for drying at a drying temperature of 50° C. for a drying time of 12 h. The dried particles are sieved and the products with appropriate particle size specifications are the immobilized glucose isomerase particles.

[0081] Verification of the catalytic performance of immobilized enzyme in glucose isomerization process:

[0082] In a 50 mL conical flask, 1.5 mL of 1 g / mL glucose solution, 4 mL of phosphate buffer (pH = 7.5), 0.5 mL of 0.061 g / mL magnesium sulfate solution and 2 mL of purified water were added, preheated in a 70 ° C shaker for 5 min, 0.5 g of the above-mentioned immobilized glucose isomerase was added, and catalytic conversion was carried out at 70 ° C, 230 rpm for 1 h.

[0083] Gas chromatography was used to analyze the component content of the product D-fructose. Chromatographic analysis showed that the conversion rate of this batch was 86.4%. The structure of the particle catalytic process collapsed and could not be used again.

[0084] The results of Example 1 and Example 2 show that increasing the amount of enzyme solution added can improve the catalytic conversion efficiency of the immobilized enzyme to a certain extent, indicating that the amount of enzyme added during the immobilization process has a certain influence on the overall catalytic performance; the results of Example 1 and Comparative Example 1 show that the addition of 2% glutaraldehyde can cause cross-linking between enzyme molecules, and after being embedded and solidified with sodium alginate, the stability can be well maintained, and the phenomenon of decreased catalytic efficiency due to enzyme leakage caused by repeated use will not occur; the results of Example 1 and Comparative Example 2 show that in the production process of immobilized enzyme, cross-linking is an unavailable key step, which is one of the reasons why the immobilized enzyme can maintain high mechanical strength. The product that is not cross-linked and solidified will collapse after being soaked in water, and cannot be used for a long time, which does not meet the economic benefit requirements of continuous production. In summary, in the production process of the immobilized enzyme of the present invention, a single immobilization method is not used, and the production process combining cross-linking and embedding is significantly better than a single solution.

[0085] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for producing immobilized glucose isomerase based on extrusion granulation, characterized in that: The specific steps are as follows: S1: Mixing the carrier and the enzyme solution: Evenly mix the inorganic carrier and the sodium alginate powder to obtain a mixed carrier, slowly add the enzyme solution into the mixed carrier, and continue to stir until uniform to form powdered enzyme particles; S2: Extrusion granulation: The powdered enzyme granules mixed in S1 are extruded and granulated. During the extrusion process, water cooling is required to cool the outlet; S3: Cross-linking and curing: 2% glutaraldehyde is added to the cross-linking agent solution, and the particles extruded from S2 are immersed in the cross-linking agent solution to form cured particles; S4: drying the particles solidified in S3; S5: The particles dried in S4 are sieved, and products with appropriate particle size specifications are the immobilized glucose isomerase particles.

2. The method for producing immobilized glucose isomerase based on extrusion granulation according to claim 1, characterized in that: In S1, the inorganic carrier is active silicon micropowder, diatomaceous earth or bentonite, and the particle size of the inorganic carrier is 1000-2500 mesh.

3. The method for producing immobilized glucose isomerase based on extrusion granulation according to claim 1 or 2, characterized in that: In S1, the particle size of the sodium alginate powder is 100-400 mesh, and the inorganic carrier is food grade; the sodium alginate powder is food grade.

4. The method for producing immobilized glucose isomerase based on extrusion granulation according to claim 3, characterized in that: The mass ratio of the inorganic carrier to the sodium alginate powder is 1:0.5 to 1:2, and the mass ratio of the mixed carrier to the enzyme solution is 1.3:1 to 2:

1.

5. The method for producing immobilized glucose isomerase based on extrusion granulation according to claim 1, characterized in that: In S3, the cross-linking agent is calcium chloride solution, barium chloride solution or zinc sulfate solution.

6. The method for producing immobilized glucose isomerase based on extrusion granulation according to claim 1 or 5, characterized in that: In S3, the concentration of the cross-linking agent solution is 2% to 7%; the curing temperature is 4 to 30° C.; and the soaking time is 1 to 3 hours.

7. The method for producing immobilized glucose isomerase based on extrusion granulation according to claim 1, characterized in that: In S4, the drying temperature is 50-60° C. and the drying time is 5-15 hours.

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