Separation method of maltose

Abstract

The invention relates to a maltose separation method, which comprises: (1) mixing a maltose conversion liquid and alpha-glucosyltransferase, and carrying out a stirring reaction; (2) heating for enzyme deactivation, adding activated carbon, and filtering; and (3) performing primary purification on the filtrate obtained by filtering through simulated moving bed chromatography, and collecting an extracting solution. The maltose conversion liquid contains maltotriose, maltotetraose and other miscellaneous sugars, the alpha-glucosyltransferase is used for converting the maltotriose and the maltotetraose to obtain maltodextrin and glucose, the ultra-high-purity maltose syrup can be obtained through one-time purification of simulated moving bed chromatography, and the method is simple, convenient and rapid and has wide application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of sugar production, and in particular to a method for separating maltose. Background Art

[0002] Maltose (D-Maltose monohydrate) has a molecular formula of C 12 H 22 O 11 ·H2O, with a molecular weight of 360.32, is present in large quantities in germinating grains, especially malt. It is a disaccharide formed by two molecules of α-D-glucose connected by α-1,4-glycosidic bonds. Since maltose contains free carbonyl groups, it is a reducing sugar. Maltose is mainly used as a carbon source in the fermentation process of beer. Maltose is mostly a transparent and viscous liquid, and it can also be concentrated, cooled and crystallized into a solid. It is one of the low-calorie, low-sweetness sugars with great development prospects. Its sweetness is equivalent to 30% to 40% of sucrose, and its calories are only 5% of sucrose. Maltose has low hygroscopicity. When maltose absorbs 6% to 12% of water, it no longer absorbs water or releases water. This hygroscopic stability helps to inhibit food dehydration and prevent starch food aging, and prolong the shelf life of food. With the rapid development of industries such as food and medicine, the continuous discovery and application of new uses for maltose, a new development trend has emerged in the requirements for maltose syrup, requiring maltose with the highest possible purity.

[0003] Simulated moving bed (SMB) chromatography is a new separation technology first developed in the petroleum industry in the 1960s. It has many advantages such as large processing capacity, high product purity, and low eluent consumption. In the following decades, it has been promoted and applied in the fields of sugar industry, food, pharmaceutical and fine chemical industry. Conventional SMB chromatography consists of four zones composed of several chromatographic columns, pumps, inlet and outlet valves and other pipe fittings, namely adsorbent regeneration zone (I), purification zone (II), adsorption zone (III) and eluent (often the same as solvent) regeneration zone (IV). Among them, the purification zone (II) and adsorption zone (III) are the main working zones, and the adsorbent regeneration zone (I) and eluent regeneration zone (IV) are the zones to ensure the recycling of adsorbent and eluent. The four inlets and outlets move synchronously along the flow direction of the mobile phase at a certain time interval, thus forming a virtual effect of the stationary phase moving in the opposite direction.

[0004] For example, CN110938714A discloses a method for producing high-purity crystalline maltose, and the specific steps are as follows: Step (1) Simulated moving bed separation After two separations in a simulated moving bed, the purity of maltose is increased from 80%-89% to more than 99%. Step (2) Crystallization The separated maltose solution is concentrated to a corresponding concentration, a certain proportion of seed crystals are added at an appropriate temperature, and the maltose is crystallized by a gradient cooling method.

[0005] In summary, how to improve the purity of maltose products has become one of the problems to be solved urgently in this field. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a method for separating maltose, which uses α-glucosyltransferase to convert maltotriose and maltotetraose to obtain maltodextrin and glucose, and then uses simulated moving bed chromatography to purify them once to obtain ultra-high purity maltose syrup. The method is simple and rapid and has broad application prospects.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for separating maltose, the separation method comprising the following steps:

[0009] (1) mixing the maltose conversion solution and α-glucosyltransferase, and stirring to react;

[0010] (2) heating to inactivate enzymes, adding activated carbon, and filtering;

[0011] (3) The filtrate obtained by filtration is purified once by simulated moving bed chromatography, and the extract is collected.

[0012] The maltose conversion liquid in the present invention is obtained by converting starch liquefaction liquid by β-amylase. The miscellaneous sugars in the maltose conversion liquid are mainly maltodextrin, maltotetraose, maltotriose and glucose. Usually, the purity of maltose in the high maltose syrup obtained by enzyme conversion is only 85%. Most of the miscellaneous sugars can be removed by purification and separation using simulated moving bed chromatography. However, since the retention time of maltotriose and maltotetraose is very close to that of maltose, it is difficult to completely separate them by one chromatography. The present invention uses α-glucosyltransferase to convert maltotriose and maltotetraose to obtain maltodextrin and glucose, and then uses simulated moving bed chromatography to purify once to obtain ultra-high purity maltose syrup.

[0013] The present invention uses a method of adding activated carbon to adsorb the pigment in the conversion liquid, and at the same time has a filtering aid effect. Since the sample entering the chromatogram can only contain a very small amount of solid particles, it is necessary to filter out the α-glucosyltransferase added in the pretreatment. The activated carbon adsorbs the α-glucosyltransferase, which helps rapid filtration.

[0014] Preferably, the maltose conversion liquid contains maltose, maltotriose, maltotetraose, glucose and maltodextrin.

[0015] Preferably, the mass percentage of maltotriose and maltotetraose is independently ≤5% (eg, 5%, 4%, 3%, 2%, 1% or 0.5%, etc.).

[0016] Preferably, the source of the α-glucosyltransferase comprises Aeribacillus pallidus.

[0017] Preferably, the mass ratio of the maltose conversion liquid to the α-glucosyltransferase is (1×10 6 ~5×10 6 ):1.

[0018] Above 1×10 6 ~5×10 6 The specific point value can be selected as 1×10 6 , 1.5×10 6 , 2×10 6 , 2.5×10 6 , 3×10 6 , 3.5×10 6 , 4×10 6 , 4.5×10 6 or 5×10 6 wait.

[0019] Preferably, the ratio of the maltose conversion liquid to the activated carbon is 1 L: (25-35) kg.

[0020] The specific point values ​​of the above (25-35) kg can be selected as 25kg, 27kg, 29kg, 30kg, 31kg, 33kg or 35kg, etc.

[0021] Preferably, step (1) further comprises the step of heating the maltose conversion liquid to 45-55° C. (for example, 45° C., 47° C., 49° C., 50° C., 51° C., 53° C. or 55° C., etc.) before the mixing.

[0022] The present invention can preheat the maltose conversion solution before adding α-glucosyltransferase, which is more conducive to the rapid progress of the enzymatic reaction.

[0023] Preferably, the stirring reaction temperature in step (1) is 45-55°C (for example, 45°C, 47°C, 49°C, 50°C, 51°C, 53°C or 55°C, etc.).

[0024] Preferably, the stirring reaction time in step (1) is 20 to 28 h (for example, 20 h, 21 h, 22 h, 23 h, 24 h, 25 h, 26 h, 27 h or 28 h, etc.).

[0025] Preferably, the temperature for heating and inactivating the enzyme in step (2) is 80-90°C (for example, it may be 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C or 90°C, etc.).

[0026] Preferably, the time for heating to inactivate the enzyme in step (2) is 20 to 40 minutes (for example, it can be 20 minutes, 25 minutes, 28 minutes, 30 minutes, 32 minutes, 35 minutes or 40 minutes, etc.).

[0027] Preferably, the pore size of the filter membrane used for filtration in step (2) is 1.5 to 2.5 μm (for example, it may be 1.5 μm, 1.7 μm, 1.9 μm, 2 μm, 2.1 μm, 2.3 μm or 2.5 μm, etc.).

[0028] Preferably, the chromatographic column filler in the simulated moving bed chromatography is sodium type resin.

[0029] Preferably, the operating temperature of the simulated moving bed chromatography is 75-85°C (for example, 75°C, 77°C, 79°C, 80°C, 81°C, 83°C or 85°C, etc.), the operating pressure is 0.2-0.4Mpa (for example, 0.2Mpa, 0.25Mpa, 0.28Mpa, 0.3Mpa, 0.32Mpa, 0.35Mpa or 0.4Mpa, etc.), the feed liquid rate is 2-4Bv / h (for example, 2 Bv / h, 2.5Bv / h, 2.8Bv / h, 3Bv / h, 3.2Bv / h, 3.5Bv / h or 4Bv / h, etc.), the mobile phase velocity is 2-4Bv / h (for example, it can be 2Bv / h, 2.5Bv / h, 2.8Bv / h, 3Bv / h, 3.2Bv / h, 3.5Bv / h or 4Bv / h, etc.), the mobile phase is water, and the mobile phase and the feed liquid are added in a volume ratio of 1: (0.8-1.2).

[0030] The specific point values ​​of the above (0.8-1.2) may be 0.8, 0.9, 0.95, 1, 1.05, 1.1 or 1.2, etc.

[0031] Preferably, after collecting the extract in step (3), the step also includes concentrating the extract to a concentration of 70% to 80% (for example, 70%, 72%, 74%, 75%, 76%, 78% or 80%, etc.).

[0032] Preferably, the separation method comprises the following steps:

[0033] (1) The maltose conversion liquid is heated to 45-55° C., the maltose conversion liquid is mixed with α-glucosyltransferase, and the mixture is stirred at 45-55° C. for 20-28 hours. The maltose conversion liquid contains maltose, maltotriose, maltotetraose, glucose and maltodextrin, the mass percentage of the maltotriose and maltotetraose is independently ≤5%, the α-glucosyltransferase is derived from Aeribacillus pallidus, and the mass ratio of the maltose conversion liquid to the α-glucosyltransferase is (1×10 6 ~5×10 6 ):1;

[0034] (2) heating at 80-90° C. to inactivate the enzyme for 20-40 min, adding activated carbon, and filtering through a 1.5-2.5 μm pore size filter membrane, wherein the ratio of the maltose conversion liquid to the activated carbon is 1 L: (25-35) kg;

[0035] (3) The filtrate obtained by filtration is purified once by simulated moving bed chromatography, and the extract is collected and concentrated to a concentration of 70% to 80%. The chromatographic column filler in the simulated moving bed chromatography is a sodium type resin, the operating temperature of the simulated moving bed chromatography is 75 to 85° C., the operating pressure is 0.2 to 0.4 MPa, the feed liquid speed is 2 to 4 Bv / h, the mobile phase speed is 2 to 4 Bv / h, the mobile phase is water, and the mobile phase and the feed liquid are added in a ratio of 1:(0.8 to 1.2) by volume.

[0036] Other specific point values ​​within the above numerical ranges can be selected and will not be described in detail here.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The invention provides a method for separating maltose. Maltotriose and maltotetraose in a maltose conversion solution are converted by alpha-glucosyltransferase to obtain maltodextrin and glucose. The alpha-glucosyltransferase is removed by filtering after activated carbon-assisted filtration. Then, ultra-high purity maltose syrup is obtained by one-time purification by simulated moving bed chromatography. The method is simple, rapid and has broad application prospects. DETAILED DESCRIPTION

[0039] To further illustrate the technical means and effects of the present invention, the present invention is further described below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention.

[0040] If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in the field or the product instructions are used. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased through regular channels.

[0041] Materials used in the following examples:

[0042] Activated carbon: purchased from Sinopharm Group, code 10006629.

[0043] Chromatographic column filler in simulated moving bed chromatography: purchased from Xi'an Lanxiao, resin model LX-1850.

[0044] Example 1

[0045] This embodiment provides a method for separating maltose, comprising the following steps:

[0046] (1) The maltose conversion liquid is heated to 50° C., the maltose conversion liquid is mixed with α-glucosyltransferase, and the mixture is stirred at 50° C. for 24 hours to obtain product A. The α-glucosyltransferase is derived from Aeribacillus pallidus, and the mass ratio of the maltose conversion liquid to the α-glucosyltransferase is 3×10 6 :1.

[0047] (2) The enzyme was inactivated by heating at 85° C. for 30 min, activated carbon was added, and the mixture was filtered through a 2 μm pore size filter membrane. The ratio of the maltose conversion liquid to the activated carbon was 1 L:30 kg.

[0048] (3) The filtrate obtained by filtration is purified once by simulated moving bed chromatography, and the extract is collected to obtain product B, and the extract is concentrated to a concentration of 75%. The chromatographic column filler in the simulated moving bed chromatography is sodium type resin, the operating temperature of the simulated moving bed chromatography is 80° C., the operating pressure is 0.3 MPa, the feed liquid speed is 3 Bv / h, the mobile phase speed is 3 Bv / h, the mobile phase is water, and the mobile phase and the feed liquid are added in a volume ratio of 1:1.

[0049] Example 2

[0050] This embodiment provides a method for separating maltose, comprising the following steps:

[0051] (1) The maltose conversion liquid is heated to 55° C., the maltose conversion liquid is mixed with α-glucosyltransferase, and the mixture is stirred at 45° C. for 28 h to obtain product A. The α-glucosyltransferase is derived from Aeribacillus pallidus, and the mass ratio of the maltose conversion liquid to the α-glucosyltransferase is 1×10 6 :1.

[0052] (2) heating at 90° C. to inactivate the enzyme for 20 min, adding activated carbon, and filtering through a 1.5 μm pore size filter membrane. The ratio of the maltose conversion liquid to the activated carbon is 1 L:35 kg.

[0053] (3) The filtrate obtained by filtration is purified once by simulated moving bed chromatography, and the extract is collected to obtain product B, and the extract is concentrated to a concentration of 70%. The chromatographic column filler in the simulated moving bed chromatography is sodium type resin, the operating temperature of the simulated moving bed chromatography is 75° C., the operating pressure is 0.4 MPa, the feed liquid speed is 2 Bv / h, the mobile phase speed is 4 Bv / h, the mobile phase is water, and the mobile phase and the feed liquid are added in a volume ratio of 1:1.2.

[0054] Example 3

[0055] This embodiment provides a method for separating maltose, comprising the following steps:

[0056] (1) The maltose conversion liquid is heated to 45°C, and the maltose conversion liquid is mixed with α-glucosyltransferase, and stirred at 55°C for 20 hours to obtain product A. The α-glucosyltransferase is derived from Aeribacillus pallidus, and the mass ratio of the maltose conversion liquid to the α-glucosyltransferase is 5×10 6 :1.

[0057] (2) heating at 80° C. to inactivate the enzyme for 40 min, adding activated carbon, and filtering through a 2.5 μm pore size filter membrane. The ratio of the maltose conversion liquid to the activated carbon is 1 L:25 kg.

[0058] (3) The filtrate obtained by filtration is purified once by simulated moving bed chromatography, and the extract is collected to obtain product B, and the extract is concentrated to a concentration of 80%. The chromatographic column filler in the simulated moving bed chromatography is sodium type resin, the operating temperature of the simulated moving bed chromatography is 85° C., the operating pressure is 0.2 MPa, the feed liquid speed is 4 Bv / h, the mobile phase speed is 2 Bv / h, the mobile phase is water, and the mobile phase and the feed liquid are added in a volume ratio of 1:0.8.

[0059] Example 4

[0060] This embodiment provides a method for separating maltose, which is different from Embodiment 1 only in that the temperature of the stirring reaction in step (1) is 42°C.

[0061] Example 5

[0062] This embodiment provides a method for separating maltose, which is different from Embodiment 1 only in that the temperature of the stirring reaction in step (1) is 57°C.

[0063] Example 6

[0064] This embodiment provides a method for separating maltose, which is different from Embodiment 1 only in that the stirring reaction time in step (1) is 18 hours.

[0065] Example 7

[0066] This embodiment provides a method for separating maltose, which is different from Embodiment 1 only in that the stirring reaction time in step (1) is 30 hours.

[0067] Example 8

[0068] This embodiment provides a method for separating maltose, which differs from the embodiment 1 only in that the mass ratio of maltose conversion liquid to α-glucosyltransferase in step (1) is 5.5×10 6 :1.

[0069] Example 9

[0070] This embodiment provides a method for separating maltose, which differs from the embodiment 1 only in that the mass ratio of maltose conversion liquid to α-glucosyltransferase in step (1) is 0.5×10 6 :1.

[0071] Example 10

[0072] This embodiment provides a method for separating maltose, which is different from Embodiment 1 only in that the ratio of maltose conversion liquid to activated carbon in step (2) is 1 L:22 kg.

[0073] Embodiment 11

[0074] This embodiment provides a method for separating maltose, which is different from Embodiment 1 only in that the ratio of maltose conversion liquid to activated carbon in step (2) is 1 L:38 kg.

[0075] Example 12

[0076] This embodiment provides a method for separating maltose, which is different from Embodiment 1 only in that the chromatographic column filler in the simulated moving bed chromatography in step (3) is a calcium type resin.

[0077] Comparative Example 1

[0078] This comparative example provides a method for separating maltose, comprising the following steps: mixing maltose conversion liquid with activated carbon, filtering with a 2 μm pore size filter membrane, wherein the ratio of the maltose conversion liquid to the activated carbon is 1 L:30 kg, and purifying the filtrate obtained by filtration once through simulated moving bed chromatography to obtain product B, wherein the conditions of the simulated moving bed chromatography are the same as those in Example 1.

[0079] Comparative Example 2

[0080] This comparative example provides a method for separating maltose, which is different from Example 1 only in that no activated carbon is added after heating to inactivate the enzyme in step (2), and 2 μm pore size filter membrane is used for direct filtration.

[0081] Test Example 1

[0082] This test example uses step (1) of the method provided in Examples 1-12 and Comparative Example 2 to perform enzyme treatment on the same maltose conversion liquid containing miscellaneous sugars, and uses high performance liquid chromatography to detect the components and mass proportions of the maltose conversion liquid and product A. The results are shown in Table 1.

[0083] Table 1

[0084]

[0085]

[0086] It can be seen from Table 1 that:

[0087] (1) Comparing Example 1 with Example 4 and Example 5, it can be seen that when the temperature of the stirring reaction is too high or too low, the enzyme activity of α-glucosyltransferase decreases, and the conversion rate of maltotriose and maltotetraose into glucose and maltodextrin decreases.

[0088] (2) Comparing Example 1 with Example 6 and Example 7, it can be seen that a too short stirring reaction time leads to an incomplete enzymatic reaction, while a too long stirring reaction time has no significant effect on the effect of the enzymatic reaction.

[0089] (3) Comparing Example 1 with Example 8 and Example 9, it can be seen that a small amount of α-glucosyltransferase leads to incomplete enzymatic reaction, while an excessive amount of enzyme has no obvious effect on the effect of the enzymatic reaction.

[0090] Test Example 2

[0091] This test example uses the product A of Examples 1-12 and Comparative Example 2 in Test Example 1, and continues to perform steps (2) and (3) in the maltose separation method. The same maltose conversion liquid is treated to separate maltose using the method provided in Comparative Example 1, and the components and mass proportion of Product B are detected. The detection method is carried out with reference to Test Example 1. Among them, the amount of activated carbon added in Example 10 is too little, the amount of activated carbon added in Example 11 is too much, and no activated carbon is added in Comparative Example 2, resulting in clogging of the filter membrane, slow filtration speed, and a large amount of maltose being retained on the filter membrane. It is impossible to perform the simulated moving bed chromatography purification in step (3), and no product B is obtained. The test results of the remaining experimental groups are shown in Table 2.

[0092] Table 2

[0093] Group maltose Maltotriose Maltotetraose glucose Maltodextrin Example 1 99.65％ 0.04％ 0.01％ 0.30％ 0％ Example 2 99.51％ 0.07％ 0.08％ 0.34％ 0％ Example 3 99.50％ 0.11％ 0.09％ 0.30％ 0％ Example 4 99.60％ 0.05％ 0.07％ 0.28％ 0％ Example 5 99.62％ 0.05％ 0.03％ 0.30％ 0％ Example 6 99.63％ 0.04％ 0.01％ 0.32％ 0％ Example 7 99.60％ 0.05％ 0.04％ 0.31％ 0％ Example 8 99.60％ 0.06％ 0.04％ 0.30％ 0％ Example 9 99.51％ 0.08％ 0.08％ 0.33％ 0％ Example 12 98.4％ 0.80％ 0.46％ 0.34％ 0％ Comparative Example 1 97.6％ 1.5％ 0.60％ 0.30％ 0％

[0094] It can be seen from Table 2 that:

[0095] (1) Comparing Example 1 with Example 12, it can be seen that the type of resin affects the separation and purification effect of maltose, and the purity of maltose is higher after separation by sodium type resin.

[0096] (2) Comparison of Example 1 with Comparative Example 1 shows that, since the retention time of maltotriose and maltotetraose is very close to that of maltose, a large amount of maltotriose and maltotetraose still remain in the product after only one separation by simulated moving bed chromatography, and the use of enzyme pretreatment effectively solves this problem.

[0097] In summary, the present invention provides a method for separating maltose, which utilizes α-glucosyltransferase to convert maltotriose and maltotetraose in the maltose conversion liquid to obtain maltodextrin and glucose, removes the α-glucosyltransferase by filtering after activated carbon assisted filtration, and then purifies once by simulated moving bed chromatography to obtain ultra-high purity maltose syrup. The method is simple and rapid and has broad application prospects.

[0098] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for separating maltose, characterized in that: The separation method comprises the following steps: (1) mixing the maltose conversion solution and α-glucosyltransferase, and stirring to react; (2) heating to inactivate enzymes, adding activated carbon, and filtering; (3) The filtrate obtained by filtration is purified once by simulated moving bed chromatography, and the extract is collected.

2. The separation method according to claim 1, characterized in that The maltose conversion liquid contains maltose, maltotriose, maltotetraose, glucose and maltodextrin; Preferably, the mass percentages of maltotriose and maltotetraose are each independently ≤5%.

3. The separation method according to claim 1 or 2, characterized in that The source of the α-glucosyltransferase includes Aeribacillus pallidus.

4. The separation method according to any one of claims 1 to 3, characterized in that: The mass ratio of the maltose conversion liquid to the α-glucosyltransferase is (1×10 6 ~5×10 6 ):1; Preferably, the ratio of the maltose conversion liquid to the activated carbon is 1 L: (25-35) kg.

5. The separation method according to any one of claims 1 to 4, characterized in that: Step (1) also includes the step of heating the maltose conversion liquid to 45-55° C. before the mixing; Preferably, the stirring reaction temperature in step (1) is 45-55°C; Preferably, the stirring reaction time in step (1) is 20 to 28 hours.

6. The separation method according to any one of claims 1 to 5, characterized in that: The temperature of heating to inactivate the enzyme in step (2) is 80-90°C; Preferably, the heating time for inactivating the enzyme in step (2) is 20 to 40 minutes; Preferably, the pore size of the filter membrane used for filtration in step (2) is 1.5 to 2.5 μm.

7. The separation method according to any one of claims 1 to 6, characterized in that: The chromatographic column filler in the simulated moving bed chromatography is sodium type resin.

8. The separation method according to any one of claims 1 to 7, characterized in that: The operating temperature of the simulated moving bed chromatography is 75-85°C, the operating pressure is 0.2-0.4Mpa, the feed liquid rate is 2-4Bv / h, the mobile phase rate is 2-4Bv / h, the mobile phase is water, and the mobile phase and the feed liquid are added in a volume ratio of 1:(0.8-1.2).

9. The separation method according to any one of claims 1 to 8, characterized in that: After collecting the extract in step (3), the step also includes concentrating the extract to a concentration of 70% to 80%.

10. The separation method according to any one of claims 1 to 9, characterized in that: The separation method comprises the following steps: (1) The maltose conversion liquid is heated to 45-55° C., the maltose conversion liquid is mixed with α-glucosyltransferase, and the mixture is stirred at 45-55° C. for 20-28 hours. The maltose conversion liquid contains maltose, maltotriose, maltotetraose, glucose and maltodextrin, the mass percentage of the maltotriose and maltotetraose is independently ≤5%, the α-glucosyltransferase is derived from Aeribacillus pallidus, and the mass ratio of the maltose conversion liquid to the α-glucosyltransferase is (1×10 6 ~5×10 6 ):1; (2) heating at 80-90° C. to inactivate the enzyme for 20-40 min, adding activated carbon, and filtering through a 1.5-2.5 μm pore size filter membrane, wherein the ratio of the maltose conversion liquid to the activated carbon is 1 L: (25-35) kg; (3) The filtrate obtained by filtration is purified once by simulated moving bed chromatography, and the extract is collected and concentrated to a concentration of 70% to 80%. The chromatographic column filler in the simulated moving bed chromatography is a sodium type resin, the operating temperature of the simulated moving bed chromatography is 75 to 85° C., the operating pressure is 0.2 to 0.4 MPa, the feed liquid speed is 2 to 4 Bv / h, the mobile phase speed is 2 to 4 Bv / h, the mobile phase is water, and the mobile phase and the feed liquid are added in a ratio of 1:(0.8 to 1.2) by volume.

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