A preparation method of crystalline isomalt

Abstract

The present invention provides a method for preparing crystalline isomalt, and belongs to the technical field of functional sugars. The present invention conducts hydrogenation reaction on isomaltulose liquid under the action of a catalyst to obtain a hydrogenation reaction liquid; the hydrogenation reaction liquid is sequentially subjected to decolorization filtration, ion exchange, and concentration to obtain a pre-crystallization material; the pre-crystallization material has a solid content of 50-55%; seed crystals are added to the pre-crystallization material, and then slowly evaporated, rapidly evaporated, and cooled and crystallized to obtain isomalt; the isomalt is centrifuged and dried to obtain crystalline isomalt, and the final isomalt crystal has a GPM purity of 48-50%, a GPS purity of 50-52%, and a moisture content of ≤1%, and no organic solvent is required, thereby reducing pollution and residue, and the preparation temperature is low and the energy consumption is low, and no new equipment needs to be added, thereby reducing the cost.

Description

Technical Field

[0001] The invention relates to the field of functional sugar technology, and in particular to a method for preparing crystalline isomalt. Background Art

[0002] Isomalt is a functional sugar alcohol composed of two substances: α-D-pyranosyl-1,1-mannitol (GPM) and α-D-pyranosyl-1,6-sorbitol (GPS). Its sweetness and calories are about half of sucrose, it is non-hygroscopic, and its melting point ranges from 145-150°C. It is a non-cariogenic sugar. In addition, isomalt does not cause an increase in blood sugar and is an ideal sweetener for diabetics. Isomalt is highly safe and has been certified as a GRAS food by the US FDA. In my country, as a new resource food, its usage is limited to ≤100 grams / day. Isomalt is mainly used in candies and chocolates.

[0003] There are few isomalt crystalline products in the prior art, most of which are powders and granules. Chinese patent CN117186161A discloses a process for preparing crystalline isomalt, which mainly uses high-purity isomalt as raw material, reacts with hydrogen under the action of a catalyst to generate an isomalt solution, and then uses vacuum evaporation crystallization and cooling crystallization to prepare isomalt. The mass content of α-D-furanosyl-1,6-sorbitol in the obtained isomalt is ≥98.5%, which is a high-purity isomalt crystal. The isomalt obtained by the crystallization process of this process is usually a substance, not a mixture of GPM and GPS; the recrystallization process is cumbersome, which is not conducive to production and application.

[0004] Chinese patent CN117603284A discloses a method for recrystallizing isomalt, comprising the following steps: obtaining isomalt conversion liquid after hydrogenation reaction, filtering to remove catalyst to obtain isomalt clear liquid, heating the isomalt clear liquid to 60-75°C, performing vacuum distillation and concentration at a vacuum degree of -0.01 to -0.05Mpa, stopping concentration when the sugar content of the sugar solution is 40-90°Bx as measured by a saccharimeter, cooling to 15-25°C, precipitating a small amount of crystals, heating it to 60-75°C, melting the crystals into liquid, dripping ethanol or methanol thereto for recrystallization, stirring, cooling, and suction filtering to obtain wet isomalt crystals, and drying to obtain dry isomalt crystals. The process of preparing molten isomalt in this process consumes too much energy.

[0005] Chinese patent CN105037454A discloses a method for preparing isomalt, comprising the following steps: (1) concentrating a liquid isomalt solution and then keeping it warm; (2) cooling an organic solvent to keep the temperature of the organic solvent below 10°C; (3) dripping molten isomalt into the organic solvent pretreated in step (2), and the isomalt droplets condense into granular solids when cooled. (4) collecting the isomalt solid obtained in step (3), drying with cold air, and obtaining the desired isomalt crystals. The use of organic solvents in the preparation process is prone to pollution and residue.

[0006] Therefore, there is an urgent need for a method for preparing crystalline isomalt containing GPS and GPM, which has low energy consumption, no organic residue, and is suitable for industrial production. Summary of the invention

[0007] In view of this, the object of the present invention is to provide a method for preparing crystalline isomalt. The isomalt crystals obtained by the present invention have a GPM purity of 48-50%, a GPS purity of 50-52%, a moisture content of ≤1%, no need to use organic solvents, thus reducing pollution and residues, and low preparation temperature and energy consumption, no need to add new equipment, thus reducing costs.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] In a first aspect, the present invention provides a method for preparing crystalline isomalt, comprising the following steps:

[0010] S1. The isomaltulose liquid is hydrogenated under the action of a catalyst to obtain a hydrogenated reaction liquid;

[0011] The purity of α-D-pyranosyl-1,1-mannitol GPM and α-D-pyranosyl-1,6-sorbitol GPS in the hydrogenation reaction liquid is 44-46% respectively;

[0012] S2. The hydrogenation reaction liquid is sequentially decolorized, filtered, ion exchanged, and concentrated to obtain a pre-crystallization material;

[0013] The solid content of the material before crystallization is 50-55%;

[0014] S3. adding seed crystals to the pre-crystallization material and then sequentially performing slow evaporation, rapid evaporation, and cooling crystallization to obtain isomalt;

[0015] S4. The isomalt is centrifuged and dried to obtain crystalline isomalt;

[0016] The purity of α-D-pyranosyl-1,1-mannitol in the isomalt crystals is 48-50%, the purity of α-D-pyranosyl-1,6-sorbitol is 50-52%, and the water content is ≤1%.

[0017] Preferably, the solid content of the isomaltulose liquid in S1 is 50-55%, and the pH is 8.5-9.5.

[0018] Preferably, the amount of catalyst added in S1 is 3-3.5% of the solid content of the isomaltulose liquid;

[0019] The catalyst is Raney nickel.

[0020] Preferably, in S1, magnesium bars with a solid content of 0.5-1.0% of the isomaltulose liquid are added before the hydrogenation reaction to maintain an alkaline environment during the reaction.

[0021] Preferably, the temperature of the hydrogenation reaction in S1 is 120-135° C., the time is 2-3 h, the pressure is 10-16 MPa, and the stirring speed is 500-800 rpm / min.

[0022] Preferably, the amount of seed crystals added in S3 is 8.0-10.0‰ of the solid content of the material before crystallization; and the seed crystals are isomalt paste ground with anhydrous ethanol.

[0023] Preferably, the temperature of the slow evaporation in S3 is 55-60°C, and the pressure is -0.05--0.08MPa; the concentration of the crystallized material after slow evaporation is 50-55%; and the amount of crystal precipitation is 20-22%.

[0024] Preferably, the temperature of the rapid evaporation in S3 is 75-85° C., and the pressure is -0.07-0.1 MPa; and the concentration of the crystallized material after rapid evaporation is 75-80%.

[0025] Preferably, the final temperature of the cooling crystallization in S3 is 25-30°C, and the cooling rate is 0.2-0.5°C / h.

[0026] In the present invention, isomalt crystals are obtained by two evaporation crystallizations and one cooling crystallization. The inventors found that GPM is easy to crystallize, and GPM is precipitated by slow evaporation crystallization. After GPM is precipitated, the GPM content in the solution is low and insufficient for precipitation. Although the GPS content is high at this time, the low concentration is insufficient for GPS to precipitate. Then, the solution concentration is quickly increased by rapid evaporation, and GPS is precipitated by cooling crystallization.

[0027] Preferably, the stirring speed of the slow evaporation, rapid evaporation and cooling crystallization is 150 rpm / min.

[0028] Beneficial technical effects:

[0029] 1. The present invention uses hydrogenated isomaltulose as a raw material, and obtains isomaltulose crystals through two evaporation crystals and one cooling crystallization; the final isomaltulose crystals have a GPM purity of 48-50%, a GPS purity of 50-52%, and a moisture content of ≤1%; the isomaltulose crystals with this composition ratio have stable chemical properties, good heat resistance, good fluidity, and are not easy to agglomerate.

[0030] 2. In the traditional preparation method, the granulation of isomalt first requires chromatographic purification of the hydrogenated solution, and then the isomalt solution needs to be concentrated to a higher concentration, close to a molten state, and then granulation requires separate equipment. The drying steps of isomalt by granulation are cumbersome, and the equipment cost and concentration cost are high. The present invention not only purifies isomalt by crystallization, but also can be produced in the same line as the crystallized product, without adding new equipment.

[0031] 3. The isomalt crystallization process of the present invention does not use organic solvents, which can avoid environmental pollution and reagent residues. DETAILED DESCRIPTION

[0032] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0033] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0034] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0035] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present application description and examples are exemplary only.

[0036] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0037] The "room temperature" and "normal temperature" mentioned in the present invention are all calculated as 25±2°C unless otherwise specified.

[0038] Unless otherwise specified, the equipment or raw materials used in the following examples can be commercially available.

[0039] Embodiment 1:

[0040] An isomalt crystal and a preparation method thereof are as follows:

[0041] S1. A catalyst Raney nickel having a solid content of 3.0% was added to an isomaltulose liquid having a solid content of 50% and a pH of 8.56, and then a magnesium bar having a solid content of 0.5% was added to maintain an alkaline environment during the reaction; a hydrogenation reaction was carried out at a temperature of 120° C., a stirring speed of 500 rpm / min, and a pressure of 10 MPa for 3 h to obtain a hydrogenation reaction liquid;

[0042] After testing, the ratio of GPM to GPS in the hydrogen reaction liquid was 44.32:44.72.

[0043] S2. The hydrogenation reaction liquid is decolorized, filtered, ion exchanged, and concentrated to obtain a pre-crystallization material of isomalt having a solid content of 50%;

[0044] The decolorization conditions are: adding activated carbon with a dry matter content of 0.5%, then keeping warm at 80°C for 30 minutes and then using plate and frame filtration;

[0045] In the ion exchange process, the resin combination is a cation resin, anion resin and cation resin in sequence; the temperature of the feed liquid entering the column in the ion exchange process is 40° C.; the pH value of the feed liquid leaving the column is 5.32; the conductivity of the outlet column is 45.67 us / cm;

[0046] The concentration conditions are as follows: the concentration temperature is 60° C. and the vacuum degree is -0.1 MPa.

[0047] S3. Adding seed crystals having a solid content of 10.0‰ to the material before crystallization, performing slow evaporation, rapid evaporation and cooling crystallization to obtain isomalt;

[0048] The seed crystals are isomalt paste ground with anhydrous ethanol;

[0049] The slow evaporation temperature is 60°C, the pressure is -0.05MPa, the rotation speed is 150rpm / min, the crystallization material concentration is controlled to be 50%, and the GPM crystal precipitation rate is 20%;

[0050] The temperature of the rapid steaming is 85°C, the pressure is -0.07MPa, the speed is 150rpm / min, and the concentration of the crystallized material is controlled to 75%;

[0051] The final temperature of the cooling crystallization is 30°C, and the cooling rate is 0.2°C / h.

[0052] S4. The isomalt is centrifuged and dried to obtain isomalt crystals;

[0053] The centrifugal speed is 1300 rpm / min and the drying temperature is 50°C;

[0054] The purity of GPM in isomalt crystals was 48.35%, the purity of GPS was 51.65%, and the water content was 0.87%.

[0055] Embodiment 2:

[0056] An isomalt crystal and a preparation method thereof are as follows:

[0057] S1. A Raney nickel catalyst with a solid content of 3.3% was added to an isomaltulose liquid with a solid content of 50% and a pH of 9.02, and then a magnesium bar with a solid content of 1.0% was added to maintain an alkaline environment during the reaction; a hydrogenation reaction was carried out at a temperature of 125° C., a stirring speed of 500 rpm / min, and a pressure of 13 MPa for 2 h to obtain a hydrogenation reaction liquid;

[0058] After testing, the ratio of GPM to GPS in the hydrogen reaction liquid was 44.52:45.08;

[0059] S2. The hydrogenation reaction liquid was decolorized, filtered, ion exchanged, and concentrated to obtain a pre-crystallization material of isomalt having a solid content of 52.5%;

[0060] The decolorization conditions are: adding activated carbon with a dry matter content of 0.5%, then keeping warm at 80°C for 30 minutes and then using plate and frame filtration;

[0061] In the ion exchange process, the resin combination is a cation resin, an anion resin and a cation resin in sequence; the temperature of the feed liquid entering the column in the ion exchange process is 40° C.; the pH value of the feed liquid leaving the column is 5.87; the conductivity of the outlet column is 45.32 us / cm;

[0062] The concentration conditions are as follows: the concentration temperature is 60° C. and the vacuum degree is -0.1 MPa.

[0063] S3. Adding seed crystals having a solid content of 8.0‰ to the material before crystallization, performing slow evaporation, rapid evaporation and cooling crystallization to obtain isomalt;

[0064] The seed crystals are isomalt paste ground with anhydrous ethanol;

[0065] The slow evaporation temperature was 57°C, the pressure was -0.07MPa, the rotation speed was 150rpm / min, the crystallization material concentration was controlled to be 52.25%, and the GPM crystal precipitation rate was 23%;

[0066] The temperature of the rapid steaming is 80°C, the pressure is -0.08MPa, the speed is 150rpm / min, and the concentration of the crystallized material is controlled to 80%;

[0067] The final temperature of the cooling crystallization is 27° C., and the cooling rate is 0.2° C. / h.

[0068] S4. The isomalt is centrifuged and dried to obtain isomalt crystals;

[0069] The centrifugal speed is 1500 rpm / min and the drying temperature is 70°C;

[0070] The results showed that the purity of GPM in isomalt crystals was 49.24%, the purity of GPS was 50.76%, and the moisture content was 0.79%.

[0071] Embodiment 3:

[0072] An isomalt crystal and a preparation method thereof are as follows:

[0073] S1. A Raney nickel catalyst with a solid content of 3.5% was added to an isomaltulose liquid with a solid content of 53% and a pH of 9.23, and then a magnesium bar with a solid content of 0.8% was added to maintain an alkaline environment during the reaction; a hydrogenation reaction was carried out at a temperature of 130° C., a stirring speed of 800 rpm / min, and a pressure of 16 MPa for 2 h to obtain a hydrogenation reaction liquid;

[0074] After testing, the ratio of GPM to GPS in the hydrogen reaction liquid was 45.01:45.43;

[0075] S2. The hydrogenation reaction liquid was decolorized, filtered, ion exchanged, and concentrated to obtain a pre-crystallization material of isomalt having a solid content of 55%;

[0076] The decolorization conditions are: adding activated carbon with a dry matter content of 0.5%, then keeping warm at 80°C for 30 minutes and then using plate and frame filtration;

[0077] In the ion exchange process, the resin combination is a cation resin, anion resin and cation resin in sequence; the temperature of the feed liquid entering the column in the ion exchange process is 40° C.; the pH value of the feed liquid leaving the column is 5.38; the conductivity of the column is 37.92 us / cm;

[0078] The concentration conditions are as follows: the concentration temperature is 60° C. and the vacuum degree is -0.1 MPa.

[0079] S3. Adding seed crystals having a solid content of 5.0‰ to the material before crystallization, performing slow evaporation, rapid evaporation and cooling crystallization to obtain isomalt;

[0080] The seed crystals are isomalt paste ground with anhydrous ethanol;

[0081] The slow evaporation temperature is 55°C, the pressure is -0.08MPa, the rotation speed is 150rpm / min, the crystallization material concentration is controlled to be 55%, and the GPM crystal precipitation rate is 22%;

[0082] The temperature of the rapid steaming is 80°C, the pressure is -0.07MPa, the speed is 150rpm / min, and the concentration of the crystallized material is controlled to 80%;

[0083] The final temperature of the cooling crystallization is 25°C, and the cooling rate is 0.5°C / h;

[0084] S4. After the isomalt is centrifuged and dried, isomalt crystals are obtained.

[0085] The centrifugal speed is 1500 rpm / min and the drying temperature is 70°C;

[0086] The results showed that the purity of GPM in isomalt crystals was 48.76%, the purity of GPS was 51.24%, and the moisture content was 0.87%.

[0087] Embodiment 4:

[0088] An isomalt crystal and a preparation method thereof are as follows:

[0089] S1. A Raney nickel catalyst with a solid content of 3.3% was added to an isomaltulose liquid with a solid content of 50% and a pH of 9.50, and then a magnesium bar with a solid content of 0.8% was added to maintain an alkaline environment during the reaction; a hydrogenation reaction was carried out at a temperature of 150° C., a stirring speed of 700 rpm / min, and a pressure of 15 MPa for 2.5 h to obtain a hydrogenation reaction liquid;

[0090] After testing, the ratio of GPM to GPS in the hydrogen reaction liquid was 45.36:45.76;

[0091] S2. The hydrogenation reaction liquid was decolorized, filtered, ion exchanged, and concentrated to obtain a pre-crystallization material of isomalt having a solid content of 52.5%;

[0092] The decolorization conditions are: adding activated carbon with a dry matter content of 0.5%, then keeping warm at 80°C for 30 minutes and then using plate and frame filtration;

[0093] In the ion exchange process, the resin combination is a cation resin, anion resin and cation resin in sequence; the temperature of the feed liquid entering the column in the ion exchange process is 40° C.; the pH value of the feed liquid leaving the column is 5.54; the conductivity of the outlet column is 47.32 us / cm;

[0094] The concentration conditions are as follows: the concentration temperature is 60° C. and the vacuum degree is -0.1 MPa.

[0095] S3. Adding seed crystals having a solid content of 10.0‰ to the material before crystallization, performing slow evaporation, rapid evaporation and cooling crystallization to obtain isomalt;

[0096] The seed crystals are isomalt paste ground with anhydrous ethanol;

[0097] The slow evaporation temperature is 60°C, the pressure is -0.07MPa, the rotation speed is 150rpm / min, the crystallization material concentration is controlled to be 52.5%, and the GPM crystal precipitation rate is 22%;

[0098] The temperature of the rapid steaming is 85°C, the pressure is -0.1MPa, the speed is 150rpm / min, and the concentration of the crystallized material is controlled to 75%;

[0099] The final temperature of the cooling crystallization is 30°C, and the cooling rate is 0.4°C / h;

[0100] S4. After the isomalt is centrifuged and dried, isomalt crystals are obtained.

[0101] The centrifugal speed is 1500 rpm / min and the drying temperature is 65°C;

[0102] The results showed that the purity of GPM in isomalt crystals was 49.54%, the purity of GPS was 50.46%, and the water content was 0.82%.

[0103] Embodiment 5:

[0104] An isomalt crystal and a preparation method thereof are as follows:

[0105] S1. A Raney nickel catalyst with a solid content of 3.0% was added to an isomaltulose liquid with a solid content of 55% and a pH of 9.16, and then a magnesium bar with a solid content of 0.8% was added to maintain an alkaline environment during the reaction; a hydrogenation reaction was carried out at a temperature of 130° C., a stirring speed of 700 rpm / min, and a pressure of 15 MPa for 3 h to obtain a hydrogenation reaction liquid;

[0106] After testing, the ratio of GPM to GPS in the hydrogen reaction liquid was 44.97:45.74;

[0107] S2. The hydrogenation reaction liquid was decolorized, filtered, ion exchanged, and concentrated to obtain a pre-crystallization material of isomalt having a solid content of 55%;

[0108] The decolorization conditions are: adding activated carbon with a dry matter content of 0.5%, then keeping warm at 80°C for 30 minutes and then using plate and frame filtration;

[0109] In the ion exchange process, the resin combination is a cation resin, anion resin and cation resin in sequence; the temperature of the feed liquid entering the column in the ion exchange process is 40° C.; the pH value of the feed liquid leaving the column is 4.98; the conductivity of the outlet column is 48.53 us / cm;

[0110] The concentration conditions are as follows: the concentration temperature is 60° C. and the vacuum degree is -0.1 MPa.

[0111] S3. Adding seed crystals having a solid content of 8.0‰ to the material before crystallization, performing slow evaporation, rapid evaporation and cooling crystallization to obtain isomalt;

[0112] The seed crystals are isomalt paste ground with anhydrous ethanol;

[0113] The slow evaporation temperature is 55°C, the pressure is -0.08MPa, the rotation speed is 150rpm / min, the crystallization material concentration is controlled to be 55%, and the GPM crystal precipitation rate is 21%;

[0114] The temperature of the rapid steaming is 80°C, the pressure is -0.1MPa, the speed is 150rpm / min, and the concentration of the crystallized material is controlled to 75%;

[0115] The final temperature of the cooling crystallization is 30°C, and the cooling rate is 0.3°C / h.

[0116] S4. The isomalt is centrifuged and dried to obtain isomalt crystals;

[0117] The centrifugal speed is 1500 rpm / min and the drying temperature is 60°C;

[0118] The results showed that the purity of GPM in isomalt crystals was 48.97%, the purity of GPS was 51.03%, and the water content was 0.86%.

[0119] Comparative Example 1:

[0120] Compared with Example 2, the concentration conditions in step S2 are 75° C., the vacuum degree is -0.1 MPa, and the solid content of the material before crystallization is 75.0%; the amount of seed added in step S3 is 10‰, and the crystallization is directly carried out by cooling, the cooling frequency is consistent with that in Example 2, and other conditions remain unchanged; the isomalt crystals obtained in step S4 have a GPM purity of 62.72%, a GPS purity of 37.28%, and a moisture content of 0.82%.

[0121] Comparative Example 2:

[0122] Compared with Example 2, direct evaporation crystallization is used in step S3 instead of segmented evaporation crystallization, the temperature is controlled at 57°C, the pressure is -0.1MPa, and 35% concentration of isomalt liquid (after decolorization, filtration, and ion exchange) is added during the evaporation crystallization process. The concentration is controlled to 75% after feeding, and then the temperature is lowered for crystallization. The cooling frequency is the same as in Example 2, and other conditions remain unchanged. The isomalt crystals obtained in step S4 have a GPM purity of 59.99%, a GPS purity of 40.01%, and a moisture content of 0.89%.

[0123] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing crystalline isomalt, characterized in that: The following steps are involved: S1. The isomaltulose liquid is hydrogenated under the action of a catalyst to obtain a hydrogenated reaction liquid; The purity of α-D-pyranosyl-1,1-mannitol and α-D-pyranosyl-1,6-sorbitol in the hydrogenation reaction liquid is 44-46% respectively; S2. The hydrogenation reaction liquid is sequentially decolorized, filtered, ion exchanged, and concentrated to obtain a pre-crystallization material; The solid content of the material before crystallization is 50-55%; S3. adding seed crystals to the pre-crystallization material and then sequentially performing slow evaporation, rapid evaporation, and cooling crystallization to obtain isomalt; The temperature of the slow evaporation in S3 is 55-60°C, and the pressure is -0.05-0.08MPa; the concentration of the crystallized material after slow evaporation is 50-55%; the amount of crystal precipitation is 20-22%; The temperature of the rapid evaporation in S3 is 75-85°C and the pressure is -0.07-0.1MPa; the concentration of the crystallized material after rapid evaporation is 75-80%; The final temperature of the cooling crystallization in S3 is 25-30°C, and the cooling rate is 0.2-0.5°C / h; S4. The isomalt is centrifuged and dried to obtain crystalline isomalt; The purity of α-D-pyranosyl-1,1-mannitol in the crystalline isomalt is 48-50%, the purity of α-D-pyranosyl-1,6-sorbitol is 50-52%; and the water content is ≤1%.

2. The method according to claim 1, characterized in that: The solid content of the isomaltulose liquid in the S1 is 50-55%, and the pH is 8.5-9.

5.

3. The method according to claim 1, characterized in that: The amount of catalyst added in S1 is 3-3.5% of the solid content of the isomaltulose liquid; The catalyst is Raney nickel.

4. The method according to claim 1, characterized in that In S1, magnesium bars with a solid content of 0.5-1.0% of isomaltulose liquid are added before the hydrogenation reaction to maintain an alkaline environment during the reaction.

5. The method according to claim 1, characterized in that: The temperature of the hydrogenation reaction in S1 is 120-135° C., the time is 2-3 h, the pressure is 10-16 MPa, and the stirring speed is 500-800 rpm / min.

6. The method according to claim 1, characterized in that The amount of seed crystals added in S3 is 8.0-10.0‰ of the solid content of the material before crystallization; the seed crystals are isomalt paste ground with anhydrous ethanol.