Method for purifying allulose-containing solution using ion exchange

Abstract

One embodiment of the present invention provides a method for purifying an allulose-containing solution, the method comprising a step of obtaining an ion-purified allulose-containing solution by passing an allulose-containing solution through an ion exchange resin column filled with a mixed-phase ion exchange resin. In the method for purifying an allulose-containing solution according to an embodiment of the present invention, the mixed-phase ion exchange resin is a mixture of a strongly acidic cation exchange resin and a weakly basic anion exchange resin, the weakly basic anion exchange resin constituting the mixed-phase ion exchange resin having an exchange capacity fraction of quaternary ammonium of 0-10%. Using the method for purifying an allulose-containing solution according to the present invention not only enables the electrical conductivity of the allulose-containing solution to be lowered to an acceptable level, but also minimizes the loss of allulose because the conversion of allulose into fructose or other materials due to a functional group of the ion exchange resin can be suppressed. Therefore, the purification method for purifying an allulose-containing solution according to an embodiment of the present invention is suitable for the mass production of high-quality allulose.

Description

Method for purifying an allulose-containing solution using ion exchange

[0001] The present invention relates to a method for purifying an allulose-containing solution, and more particularly, to a method for minimizing allulose loss when purifying an allulose-containing solution using an ion exchange resin.

[0002] D-allulose is an epimer of fructose at the 3-carbon atom and is also called D-psicose. D-allulose is a functional monosaccharide that can be used as a low-calorie sweetener in diet foods because it has 70% the sweetness of sucrose (Oshima 2006) but only 0.3% the energy content (Matsuo et al. 2002). In addition, D-allulose has the function of suppressing glucose absorption and blood sugar, so it can be applied to foods for diabetic patients and foods for those receiving treatment, and it can suppress abdominal fat accumulation by suppressing enzyme activity involved in lipid synthesis in the liver, so it can be used in various functional foods such as health foods (Matsuo et al. 2001; Iida et al. 2008; Hayashi et al. 2010; Hossain et al. 2011).

[0003] Due to the above characteristics, allulose is a good source that can replace sugar, but since it belongs to the rare sugar, which is a monosaccharide that exists extremely rarely in nature, a method for efficiently producing allulose is needed to apply it to the food industry. The most efficient method for producing allulose for industrialization is the method of converting fructose into allulose using D-allulose 3-epimerase. The D-allulose-containing reaction product produced by the enzymatic reaction is then filtered, decolorized, concentrated, and ion exchange purified to produce a low-purity solution with a D-allulose content of approximately 20-30% (w / w) on a solids basis. In addition, the low-purity solution with a D-allulose content of approximately 20-30% (w / w) is produced as a high-purity solution with a D-allulose content of approximately 95-99% (w / w) on a solids basis through simulated moving bed (SMB) chromatography separation and ion exchange purification.

[0004] In relation to allulose purification technology, Korean Patent Publication No. 10-1988441 discloses an allulose purification method, including the steps of mixing an allulose conversion reactant and powdered activated carbon, performing a solid-liquid separation process on the mixture to remove impurities and activated carbon, and obtaining a filtrate; performing an ion purification process using a column packed with an ion exchange resin after performing an activated carbon treatment step; and performing an allulose separation step to obtain an allulose fraction and a fructose raffinate by performing a simulated moving bed (SMB) chromatography separation process.

[0005] The present invention has been derived under the conventional technical background, and the purpose of the present invention is to provide a method for purifying an allulose-containing solution that can minimize allulose loss while achieving an acceptable level of ion purification efficiency using an ion exchange resin.

[0006] When performing ion exchange purification of a reaction product containing D-allulose to produce a low-purity solution-type product with a D-allulose content of approximately 20-30% (w / w) on a solids basis, some of the allulose is converted to fructose or other substances due to the functional groups of the ion exchange resin, resulting in allulose loss. In addition, when performing ion exchange purification after simulated moving bed (SMB) chromatography separation to produce a high-purity solution-type product with a D-allulose content of approximately 95-99% (w / w) on a solids basis, a mixed ion exchange resin composed of a strongly acidic cation exchange resin and a strongly basic anion exchange resin is generally used, but in this case, a very large loss of allulose occurs. The inventors of the present invention recognized a unique problem occurring in the process of purifying an allulose-containing solution using ion exchange, and to solve the problem, conducted experiments to purify an allulose-containing solution using various combinations of ion exchange resin columns, and as a result, confirmed that allulose loss was minimized when a specific combination of ion exchange resins was used, and completed the present invention.

[0007]

[0008] In order to solve the above problem, one example of the present invention provides a method for purifying an allulose-containing solution, including the step of passing the allulose-containing solution through an ion exchange resin column filled with a mixed-bed ion exchange resin to obtain an ion-purified allulose-containing solution. In the method for purifying an allulose-containing solution according to one example of the present invention, the mixed-bed ion exchange resin is a mixture of a strongly acidic cation exchange resin and a weakly basic anion exchange resin, and the weakly basic anion exchange resin constituting the mixed-bed ion exchange resin has an exchange capacity fraction of quaternary ammonium of 0 to 10%.

[0009] In order to solve the above problem, another example of the present invention provides a method for purifying an allulose-containing solution, including the step of sequentially passing an allulose-containing solution through a first ion exchange resin column filled with a strongly acidic cation exchange resin, a second ion exchange resin column filled with a weakly basic anion exchange resin, and a third ion exchange resin column filled with a mixed-bed ion exchange resin to obtain an ion-purified allulose-containing solution. In the method for purifying an allulose-containing solution according to another example of the present invention, the mixed-bed ion exchange resin is a mixture of a strongly acidic cation exchange resin and a weakly basic anion exchange resin. In addition, in the method for purifying an allulose-containing solution according to another example of the present invention, the weakly basic anion exchange resin filled in the second ion exchange resin column and the weakly basic anion exchange resin constituting the mixed-bed ion exchange resin have an exchange capacity fraction of quaternary ammonium of 0 to 10%.

[0010] The method for purifying an allulose-containing solution according to the present invention not only reduces the electrical conductivity of the allulose-containing solution to an acceptable level, but also minimizes allulose loss by inhibiting the conversion of allulose to fructose or other substances due to the functional groups of the ion exchange resin. Therefore, the method for purifying an allulose-containing solution according to the present invention is suitable for mass-producing high-quality allulose.

[0011] Hereinafter, the present invention will be described in detail.

[0012] The term 'exchange capacity fraction' used in the present invention is the exchange capacity contributed by a specific exchanger to the total exchange capacity of the ion exchange resin, expressed as a percentage.

[0013]

[0014] The present invention relates to a method for purifying an allulose-containing solution, which can minimize allulose loss while achieving an acceptable level of ion purification efficiency using an ion exchange resin.

[0015]

[0016] A method for purifying an allulose-containing solution according to one embodiment of the present invention comprises the step of passing the allulose-containing solution through an ion exchange resin column filled with a mixed-phase ion exchange resin to obtain an ion-purified allulose-containing solution. The mixed-phase ion exchange resin is a mixture of a strongly acidic cation exchange resin and a weakly basic anion exchange resin.

[0017] The type of the strong acid cation exchange resin constituting the above-mentioned mixed phase ion exchange resin is not particularly limited, and may be selected from, for example, hydrogen ion type (H type) or sodium type (Na type) strong acid cation exchange resins. When using the Na type strong acid cation exchange resin, it may be converted to the H type using an acid (e.g., HCl) aqueous solution of an appropriate concentration before use and then used. In addition, the strong acid cation exchange resin may be a gel type or a porous type, and the porous type is preferable. In addition, the strong acid cation exchange resin has a sulfonic acid group as an exchange group, and the parent may be a styrene-divinylbenzene copolymer manufactured by polymerizing a monovinylidene aromatic monomer (e.g., styrene, etc.) and a crosslinking agent (e.g., divinylbenzene (DVB), etc.).

[0018] The weakly basic anion exchange resin constituting the above mixed-phase ion exchange resin is not particularly limited in type as long as the exchange capacity fraction of quaternary ammonium is 0 to 10%. For example, the weakly basic anion exchange resin may be a gel type or a porous type, and the porous type is preferable. In addition, the weakly basic anion exchange resin has a tertiary amine group or a quaternary ammonium group as an exchange group, and the matrix may be a styrene-divinylbenzene copolymer manufactured by polymerizing a monovinylidene aromatic monomer (e.g., styrene, etc.) and a crosslinking agent (e.g., divinylbenzene (DVB), etc.). The quaternary ammonium group, which is an exchange group present in the above weakly basic anion exchange resin, is selected from a type Ⅰ quaternary ammonium group such as trimethyl ammonium or a type Ⅱ quaternary ammonium group such as dimethylethanol ammonium, and is preferably a type Ⅰ quaternary ammonium group such as trimethyl ammonium when considering purification efficiency and minimization of allulose loss. The weakly basic anion exchange resin constituting the above mixed-phase ion exchange resin has a tertiary amine group as an exchange group when the exchange capacity fraction of the quaternary ammonium is 0%, and the exchange capacity fraction of the tertiary amine group is 100%. In addition, the weakly basic anion exchange resin constituting the mixed-bed ion exchange resin has a quaternary ammonium group and a tertiary amine group as exchangers when the exchange capacity fraction of quaternary ammonium is 5%, and the exchange capacity fraction of the tertiary amine group is 95%. In addition, the weakly basic anion exchange resin constituting the mixed-bed ion exchange resin has a quaternary ammonium group and a tertiary amine group as exchangers when the exchange capacity fraction of quaternary ammonium is 10%, and the exchange capacity fraction of the tertiary amine group is 90%. Considering the ion purification efficiency, the weakly basic anion exchange resin constituting the mixed-bed ion exchange resin preferably has a quaternary ammonium exchange capacity fraction of 5 to 10%.

[0019] In a method for purifying an allulose-containing solution according to an example of the present invention, the mixing volume ratio of the strongly acidic cation exchange resin and the weakly basic anion exchange resin constituting the mixed-phase ion exchange resin is not significantly limited, and considering ion purification efficiency and minimization of allulose loss, it is preferably 1:1 to 1:4, and more preferably 1:1.5 to 1:3.

[0020] In a method for purifying an allulose-containing solution according to an example of the present invention, the sugar solids concentration, pH, electrical conductivity, allulose content, etc. of the allulose-containing solution injected into the ion exchange resin column are not particularly limited. Considering ion purification efficiency, the allulose-containing solution preferably has a sugar solids concentration of 5 to 50 Brix, a pH of 3.5 to 5.5, an electrical conductivity of 5 to 80 μS / cm, and an allulose content of 90 to 99% (w / w) based on the total solids weight, and more preferably has a sugar solids concentration of 8 to 30 Brix, a pH of 4 to 5, an electrical conductivity of 15 to 60 μS / cm, and an allulose content of 95 to 99% (w / w) based on the total solids weight.

[0021] In the method for purifying an allulose-containing solution according to an example of the present invention, the temperature of the ion exchange resin column is preferably 30 to 55°C, and more preferably 40 to 50°C, considering ion purification efficiency and minimization of allulose loss. In addition, in the method for purifying an allulose-containing solution according to an example of the present invention, when the allulose-containing solution passes through the ion exchange resin column, the space velocity (SV) is not significantly limited, and in consideration of ion purification efficiency, it is preferably 1 to 5, and more preferably 1.5 to 3.

[0022]

[0023] A method for purifying an allulose-containing solution according to another example of the present invention includes a step of sequentially passing the allulose-containing solution through a first ion exchange resin column filled with a strongly acidic cation exchange resin, a second ion exchange resin column filled with a weakly basic anion exchange resin, and a third ion exchange resin column filled with a mixed-bed ion exchange resin to obtain an ion-purified allulose-containing solution.

[0024] In another example of the method for purifying an allulose-containing solution according to the present invention, the type of the strong acid cation exchange resin charged in the first ion exchange resin column is not particularly limited, and may be selected from, for example, hydrogen ion type (H type) or sodium type (Na type) strong acid cation exchange resins. When the Na type strong acid cation exchange resin is used, it may be converted to the H type using an acid (e.g., HCl) aqueous solution of an appropriate concentration before use and then used. In addition, the strong acid cation exchange resin may be a gel type or a porous type, and a gel type is preferable. In addition, the strong acid cation exchange resin has a sulfonic acid group as an exchange group, and the parent may be a styrene-divinylbenzene copolymer manufactured by polymerizing a monovinylidene aromatic monomer (e.g., styrene, etc.) and a crosslinking agent (e.g., divinylbenzene (DVB), etc.).

[0025] In another example of the method for purifying an allulose-containing solution according to the present invention, the type of the weakly basic anion exchange resin charged in the second ion exchange resin column is not particularly limited as long as the exchange capacity fraction of quaternary ammonium is 0 to 10%. For example, the weakly basic anion exchange resin may be a gel type or a porous type, and the porous type is preferable. In addition, the weakly basic anion exchange resin has a tertiary amine group or a quaternary ammonium group as an exchange group, and the matrix may be a styrene-divinylbenzene copolymer manufactured by polymerizing a monovinylidene aromatic monomer (e.g., styrene, etc.) and a crosslinking agent (e.g., divinylbenzene (DVB), etc.). The quaternary ammonium group as an exchange group present in the above weakly basic anion exchange resin is selected from a type Ⅰ quaternary ammonium group such as trimethyl ammonium or a type Ⅱ quaternary ammonium group such as dimethylethanol ammonium, and is preferably a type Ⅰ quaternary ammonium group such as trimethyl ammonium when considering purification efficiency and minimization of allulose loss. The above weakly basic anion exchange resin has a tertiary amine group as an exchange group when the exchange capacity fraction of quaternary ammonium is 0%, and the exchange capacity fraction of the tertiary amine group is 100%. In addition, the above weakly basic anion exchange resin has a quaternary ammonium group and a tertiary amine group as exchange groups when the exchange capacity fraction of quaternary ammonium is 5%, and the exchange capacity fraction of the tertiary amine group is 95%. In addition, the above weakly basic anion exchange resin has a quaternary ammonium group and a tertiary amine group as exchangers when the exchange capacity fraction of quaternary ammonium is 10%, and the exchange capacity fraction of tertiary amine groups is 90%. The weakly basic anion exchange resin charged in the second ion exchange resin column preferably has a tertiary amine group as exchangers and the exchange capacity fraction of quaternary ammonium is 0% when considering ion purification efficiency and minimization of allulose loss.

[0026] In another embodiment of the method for purifying an allulose-containing solution according to the present invention, the mixed-bed ion exchange resin packed in the third ion exchange resin column is a mixture of a strongly acidic cation exchange resin and a weakly basic anion exchange resin. The weakly basic anion exchange resin constituting the mixed-bed ion exchange resin preferably has a quaternary ammonium exchange capacity fraction of 0 to 10%, and in consideration of ion purification efficiency and minimization of allulose loss, the quaternary ammonium exchange capacity fraction is preferably 5 to 10%. In addition, the mixing volume ratio of the strongly acidic cation exchange resin and the weakly basic anion exchange resin constituting the mixed-bed ion exchange resin is preferably 1:1 to 1:4. In another embodiment of the method for purifying an allulose-containing solution according to the present invention, the technical characteristics of the mixed-bed ion exchange resin packed in the third ion exchange resin column are the same as those described in the method for purifying an allulose-containing solution according to an embodiment of the present invention, and thus a detailed description thereof will be omitted.

[0027] In a method for purifying an allulose-containing solution according to another example of the present invention, the volume ratio of the strongly acidic cation exchange resin packed in the first ion exchange resin column, the weakly basic anion exchange resin packed in the second ion exchange resin column, and the mixed-bed ion exchange resin packed in the third ion exchange resin column is not particularly limited, and considering ion purification efficiency, it is preferably 1:(0.5~2):(0.5~2), and more preferably 1:(0.65~1.5):(0.65~1.5).

[0028] In a method for purifying an allulose-containing solution according to another example of the present invention, the sugar solids concentration, pH, electrical conductivity, allulose content, etc. of the allulose-containing solution injected into the first ion exchange resin column are not particularly limited. Considering ion purification efficiency, the allulose-containing solution preferably has a sugar solids concentration of 25 to 65 Brix, a pH of 3.5 to 5.5, an electrical conductivity of 20 to 400 μS / cm, and an allulose content of 10 to 50% (w / w) based on the total solids weight, and more preferably has a sugar solids concentration of 40 to 60 Brix, a pH of 4 to 5, an electrical conductivity of 50 to 250 μS / cm, and an allulose content of 15 to 35% (w / w) based on the total solids weight.

[0029] In the method for purifying an allulose-containing solution according to an example of the present invention, the temperature of the first ion exchange resin column, the second ion exchange resin column, and the third ion exchange resin column is preferably 30 to 55°C, and more preferably 35 to 45°C, considering ion purification efficiency and minimization of allulose loss. In addition, in the method for purifying an allulose-containing solution according to another example of the present invention, when the allulose-containing solution passes through the first ion exchange resin column, the second ion exchange resin column, and the third ion exchange resin column, the space velocity (SV) is not significantly limited, and in consideration of ion purification efficiency, it is preferably 1 to 5, and more preferably 1.5 to 3.

[0030]

[0031] Hereinafter, the present invention will be described in more detail through examples. However, the following examples are intended only to clearly illustrate the technical features of the present invention and do not limit the scope of protection of the present invention.

[0032]

[0033] 1. Ion exchange resin information

[0034] Table 1 below summarizes information on ion exchange resins used in the examples of the present invention. All ion exchange resin products listed in Table 1 below are commercially available.

[0035] Ion exchange resin internal management name DS1 DS2 DS3 DS4 DS5 DS6 Resin type Strongly acidic cation exchange resin Strongly acidic cation exchange resin Medium basic anion exchange resin Weakly basic anion exchange resin Weakly basic anion exchange resin Strongly basic anion exchange resin Resin particle type Gel type Porous type Porous type Porous type Porous type Porous type Resin matrix material Styrene-divinylbenzene copolymer Styrene-divinylbenzene copolymer Styrene-divinylbenzene copolymer Styrene-divinylbenzene copolymer Styrene-divinylbenzene copolymer Styrene-divinylbenzene copolymer Resin particle uniformity Monodisperse Monodisperse Monodisperse Monodisperse Monodisperse Non-uniform Monodisperse All Exchange capacity (eq / L) 2.1~2.2 1.6~1.8 1.3~1.4 1.6 1.7~2.0 1.0~1.1 Functional technology Sulfonic acid Tertiary amine, quaternary ammonium Tertiary amine, quaternary ammonium Tertiary amine Quaternary ammonium (Type Ⅱ) Fraction of exchange capacity occupied by quaternary ammonium 25% 5~10% 0% 100%

[0036]

[0037] 2. Ion exchange purification of allulose-containing solution

[0038] Experimental Example 1.

[0039] An isomerization reaction was carried out by contacting a fructose solution with an immobilized allulose epimerase. Thereafter, activated carbon was added to the reaction product solution, and a decolorization reaction was carried out at 50°C, followed by filtration and concentration to prepare a low-purity allulose-containing solution having a sugar solid concentration of about 50 Brix, a pH of about 4.5, and an electrical conductivity of about 108 μS / cm. The allulose content in the low-purity allulose-containing solution was about 20.44% (w / w) based on the total weight of the solid content. A mixed-bed ion exchange resin was prepared by mixing a strongly acidic cation exchange resin (product name: DS2) and a weakly basic anion exchange resin (product name: DS4) in a volume ratio of 1:2. Afterwards, a first column filled with a strongly acidic cation exchange resin (product name: DS1), a second column filled with a weakly basic anion exchange resin (product name: DS5), and a third column filled with a mixed-bed ion exchange resin were sequentially connected to prepare a total of three ion exchange resin columns. The volume ratio of the cation exchange resin filled in the first column, the anion exchange resin filled in the second column, and the mixed ion exchange resin filled in the third column was 1:1.5:1. Thereafter, the temperature of the ion exchange resin column was maintained at 45°C, and a low-purity allulose-containing solution was passed through the ion exchange resin column at a space velocity (SV) of 2.6 to obtain an ion-purified allulose-containing solution.

[0040]

[0041] Experimental example 2.

[0042] An isomerization reaction was carried out by contacting a fructose solution with immobilized allulose epimerase. Thereafter, activated carbon was added to the reaction product solution, and a decolorization reaction was carried out at 50°C, followed by filtration and concentration to prepare a low-purity allulose-containing solution having a sugar solid concentration of about 50 Brix, a pH of about 4.5, and an electrical conductivity of about 118 μS / cm. The allulose content in the low-purity allulose-containing solution was about 20.30% (w / w) based on the total weight of the solid content. A mixed-bed ion exchange resin was prepared by mixing a strongly acidic cation exchange resin (product name: DS2) and a weakly basic anion exchange resin (product name: DS4) in a volume ratio of 1:2. Afterwards, a first column filled with a strongly acidic cation exchange resin (product name: DS1), a second column filled with a weakly basic anion exchange resin (product name: DS4), and a third column filled with a mixed-bed ion exchange resin were sequentially connected to prepare a total of three ion exchange resin columns. The volume ratio of the cation exchange resin filled in the first column, the anion exchange resin filled in the second column, and the mixed ion exchange resin filled in the third column was 1:1.5:1. Thereafter, the temperature of the ion exchange resin column was maintained at 45°C, and a low-purity allulose-containing solution was passed through the ion exchange resin column at a space velocity (SV) of 2.6 to obtain an ion-purified allulose-containing solution.

[0043]

[0044] Experimental Example 3.

[0045] An isomerization reaction was carried out by contacting a fructose solution with an immobilized allulose epimerase. Thereafter, activated carbon was added to the reaction product solution, and a decolorization reaction was carried out at 50°C, followed by filtration and concentration to prepare a low-purity allulose-containing solution having a sugar solid concentration of about 50 Brix, a pH of about 4.4, and an electrical conductivity of about 101 μS / cm. The allulose content in the low-purity allulose-containing solution was about 20.41% (w / w) based on the total weight of the solid content. A mixed-bed ion exchange resin was prepared by mixing a strongly acidic cation exchange resin (product name: DS2) and a weakly basic anion exchange resin (product name: DS4) in a volume ratio of 1:2. Afterwards, a first column filled with a strongly acidic cation exchange resin (product name: DS1), a second column filled with a medium basic anion exchange resin (product name: DS3), and a third column filled with a mixed-bed ion exchange resin were sequentially connected to prepare a total of three ion exchange resin columns. The volume ratio of the cation exchange resin filled in the first column, the anion exchange resin filled in the second column, and the mixed ion exchange resin filled in the third column was 1:1.5:1. Thereafter, the temperature of the ion exchange resin column was maintained at 45°C, and a low-purity allulose-containing solution was passed through the ion exchange resin column at a space velocity (SV) of 2.6 to obtain an ion-purified allulose-containing solution.

[0046]

[0047] Experimental Example 4.

[0048] An isomerization reaction was carried out by contacting a fructose solution with immobilized allulose epimerase. Thereafter, activated carbon was added to the reaction product solution, and a decolorization reaction was carried out at 50°C, followed by filtration and concentration to prepare a low-purity allulose-containing solution having a sugar solid concentration of about 50 Brix, a pH of about 4.5, and an electrical conductivity of about 105 μS / cm. The allulose content in the low-purity allulose-containing solution was about 20.39% (w / w) based on the total weight of the solid content. A mixed-bed ion exchange resin was prepared by mixing a strongly acidic cation exchange resin (product name: DS2) and a strongly basic anion exchange resin (product name: DS6) in a volume ratio of 1:2. Afterwards, a first column filled with a strongly acidic cation exchange resin (product name: DS1), a second column filled with a medium basic anion exchange resin (product name: DS3), and a third column filled with a mixed-bed ion exchange resin were sequentially connected to prepare a total of three ion exchange resin columns. The volume ratio of the cation exchange resin filled in the first column, the anion exchange resin filled in the second column, and the mixed ion exchange resin filled in the third column was 1:1.5:1. Thereafter, the temperature of the ion exchange resin column was maintained at 45°C, and a low-purity allulose-containing solution was passed through the ion exchange resin column at a space velocity (SV) of 2.6 to obtain an ion-purified allulose-containing solution.

[0049]

[0050] Experimental Example 5.

[0051] A fructose solution was brought into contact with immobilized allulose epimerase to carry out an isomerization reaction. Thereafter, activated carbon was added to the reaction product solution, and a decolorization reaction was performed at 50°C, followed by filtration, concentration, and ion exchange resin purification to obtain a low-purity allulose-containing solution. Thereafter, a simulated moving bed (SMB) chromatography separation process was performed on the low-purity allulose-containing solution using a column packed with a cation exchange resin having a calcium-activated group attached thereto, thereby preparing a high-purity allulose-containing solution having a sugar solid concentration of about 10 Brix, a pH of about 4.5, and an electrical conductivity of about 36 μS / cm. The allulose content in the high-purity allulose-containing solution was about 97.96% (w / w) based on the total weight of the solids. A mixed-bed ion exchange resin was prepared by mixing a strongly acidic cation exchange resin (product name: DS2) and a weakly basic anion exchange resin (product name: DS4) in a volume ratio of 1:2. Then, an ion exchange resin column filled with the mixed-bed ion exchange resin was prepared. Thereafter, the temperature of the ion exchange resin column was maintained at 45°C, and a high-purity allulose-containing solution was passed through the ion exchange resin column at a space velocity (SV) of 2.6 to obtain an ion-purified allulose-containing solution.

[0052]

[0053] Experimental Example 6.

[0054] A fructose solution was brought into contact with immobilized allulose epimerase to carry out an isomerization reaction. Thereafter, activated carbon was added to the reaction product solution, and a decolorization reaction was performed at 50°C, followed by filtration, concentration, and ion exchange resin purification to obtain a low-purity allulose-containing solution. Thereafter, a simulated moving bed (SMB) chromatography separation process was performed on the low-purity allulose-containing solution using a column packed with a cation exchange resin having a calcium-activated group attached thereto, thereby preparing a high-purity allulose-containing solution having a sugar solid concentration of about 10 Brix, a pH of about 4.5, and an electrical conductivity of about 40 μS / cm. The allulose content in the high-purity allulose-containing solution was about 98.3% (w / w) based on the total weight of the solids. A mixed-bed ion exchange resin was prepared by mixing a strongly acidic cation exchange resin (product name: DS2) and a moderately basic anion exchange resin (product name: DS3) in a volume ratio of 1:2. Then, an ion exchange resin column filled with the mixed-bed ion exchange resin was prepared. Thereafter, the temperature of the ion exchange resin column was maintained at 45°C, and a high-purity allulose-containing solution was passed through the ion exchange resin column at a space velocity (SV) of 2.6 to obtain an ion-purified allulose-containing solution.

[0055]

[0056] Experimental Example 7.

[0057] An isomerization reaction was carried out by contacting a fructose solution with an immobilized allulose epimerase. Thereafter, activated carbon was added to the reaction product solution, and a decolorization reaction was carried out at 50°C, followed by filtration, concentration, and ion exchange resin purification to obtain a low-purity allulose-containing solution. Thereafter, a simulated moving bed (SMB) chromatography separation process was performed on the low-purity allulose-containing solution using a column packed with a cation exchange resin having a calcium-activated group attached thereto, thereby preparing a high-purity allulose-containing solution having a sugar solid concentration of about 10 Brix, a pH of about 4.5, and an electrical conductivity of about 36 μS / cm. The allulose content in the high-purity allulose-containing solution was about 97.63% (w / w) based on the total weight of the solids. A mixed-bed ion exchange resin was prepared by mixing a strongly acidic cation exchange resin (product name: DS2) and a strongly basic anion exchange resin (product name: DS6) in a volume ratio of 1:2. Then, an ion exchange resin column filled with the mixed-bed ion exchange resin was prepared. Thereafter, the temperature of the ion exchange resin column was maintained at 45°C, and a high-purity allulose-containing solution was passed through the ion exchange resin column at a space velocity (SV) of 2.6 to obtain an ion-purified allulose-containing solution.

[0058]

[0059] The ion exchange resin combinations used in Experimental Examples 1 to 7 are summarized in Table 2 below.

[0060] Experimental example Classification Ion exchange resin combination (order of passage of allulose-containing solution) Cation exchange resin (1st stage) Anion exchange resin (2nd stage) Hybrid ion exchange resin (3rd stage) Experimental example 1 Strongly acidic cation exchange resin DS1 Weakly basic anion exchange resin DS5 Strongly acidic cation exchange resin DS2 + weakly basic anion exchange resin DS4 Experimental example 2 Strongly acidic cation exchange resin DS1 Weakly basic anion exchange resin DS4 Strongly acidic cation exchange resin DS2 + weakly basic anion exchange resin DS4 Experimental example 3 Strongly acidic cation exchange resin DS1 Medium basic anion exchange resin DS3 Strongly acidic cation exchange resin DS2 + weakly basic anion exchange resin DS4 Experimental example 4 Strongly acidic cation exchange resin DS1 Medium basic anion exchange resin DS3 Strongly acidic cation exchange resin DS2 + strong basic anion exchange resin DS4 DS6 Experimental Example 5 - Strongly acidic cation exchange resin DS2 + weakly basic anion exchange resin DS4 Experimental Example 6 - Strongly acidic cation exchange resin DS2 + moderately basic anion exchange resin DS3 Experimental Example 7 - Strongly acidic cation exchange resin DS2 + strongly basic anion exchange resin DS6

[0061] Table 3 below summarizes the changes in the physical properties of an allulose-containing solution before being injected into an ion exchange resin column and after being discharged through the ion exchange resin column.

[0062] Experimental example Classification Allulose-containing solution before injection Allulose-containing solution after discharge Allulose loss rate (%) pH conductivity (㎛ / cm) Allulose content (%) pH conductivity (㎲ / cm) Allulose content (%) Experimental example 14.5 10 8 20.44 6.7 21.25 20.35 0.44 Experimental example 24.5 1 1 8 20.30 6.5 11.23 19.9 11.92 Experimental example 34.4 10 1 20.41 6.42 0.86 19.82 2.89 Experimental example 44.5 1 0 5 20.39 6.7 21.01 17.57 13.83 Experimental example 54.5 3 6 9 7.96 6.41 29 7.54 0.43 Experimental example Experimental Example 74.53697.634.430.883.8314.14

[0063] * Allulose content: Weight percentage (%, w / w) based on total weight of solids

[0064] * Allulose loss rate: The rate at which allulose is converted into fructose or other substances through isomerization, etc. when passing through an ion exchange resin.

[0065]

[0066] As shown in Tables 2 and 3 above, the allulose-containing solution discharged through the ion exchange resin column showed acceptable pH and conductivity levels regardless of the combination of ion exchange resins. However, the allulose loss caused by isomerization reactions, etc. when the allulose-containing solution was purified by passing through the ion exchange resin column showed a large difference depending on the combination of ion exchange resins. Specifically, the allulose loss was minimized in Experimental Examples 1, 2, and 5. The ion exchange resin columns used in Experimental Examples 1, 2, and 5 commonly included a mixed-bed ion exchange resin manufactured by mixing a strongly acidic cation exchange resin (product name: DS2) and a weakly basic anion exchange resin (product name: DS4) in a volume ratio of 1:2. Meanwhile, the ion exchange resin column used in Experimental Example 3 also included a mixed-bed ion exchange resin manufactured by mixing a strongly acidic cation exchange resin (product name: DS2) and a weakly basic anion exchange resin (product name: DS4) in a volume ratio of 1:2, but the loss of allulose in Experimental Example 3 was somewhat large. This result is due to the difference in the anion exchange resin located in the second stage of the ion exchange resin column. In Experimental Examples 1 and 2, the anion exchange resins located in the second stage were a weakly basic anion exchange resin (product name: DS5) in which the exchange capacity fraction occupied by quaternary ammonium was 0% and a weakly basic anion exchange resin (product name: DS4) in which the exchange capacity fraction occupied by quaternary ammonium was 5 to 10%, respectively, whereas in Experimental Example 3, the anion exchange resin located in the second stage was a medium basic anion exchange resin (product name: DS3) in which the exchange capacity fraction occupied by quaternary ammonium was 25%. The result showed that as the exchange capacity fraction occupied by quaternary ammonium of the anion exchange resin located in the second stage of the ion exchange resin column increased, the allulose loss rate also increased, and from the perspective of mass production, it is preferable that the exchange capacity fraction occupied by quaternary ammonium of the anion exchange resin located in the second stage of the ion exchange resin column be 0 to 10%.

[0067]

[0068] While the present invention has been described through exemplary embodiments, it should be understood that the invention is not necessarily limited to these specific embodiments. Various modifications and variations are possible without departing from the scope and spirit of the invention. Therefore, the scope of protection of the present invention should be interpreted to encompass all embodiments falling within the scope of the appended claims.

Claims

1. A method comprising the step of passing an allulose-containing solution through an ion exchange resin column filled with a mixed-phase ion exchange resin to obtain an ion-purified allulose-containing solution, The above mixed ion exchange resin is a mixture of a strongly acidic cation exchange resin and a weakly basic anion exchange resin. A method for purifying an allulose-containing solution, wherein the weakly basic anion exchange resin constituting the above-mentioned mixed phase ion exchange resin has an exchange capacity fraction of quaternary ammonium of 0 to 10%.

2. A method for purifying an allulose-containing solution, characterized in that the weakly basic anion exchange resin constituting the mixed phase ion exchange resin in paragraph 1 has an exchange capacity fraction of quaternary ammonium of 5 to 10%.

3. A method for purifying an allulose-containing solution, characterized in that in paragraph 1, the mixing volume ratio of the strongly acidic cation exchange resin and the weakly basic anion exchange resin constituting the mixed ion exchange resin is 1:1 to 1:

4.

4. A method for purifying an allulose-containing solution, characterized in that the allulose-containing solution injected into the ion exchange resin column according to any one of claims 1 to 3 has a sugar solids concentration of 5 to 50 Brix, a pH of 3.5 to 5.5, an electrical conductivity of 5 to 80 ㎲ / cm, and an allulose content of 90 to 99% (w / w) based on the total solids weight.

5. A method comprising the step of sequentially passing an allulose-containing solution through a first ion exchange resin column filled with a strongly acidic cation exchange resin, a second ion exchange resin column filled with a weakly basic anion exchange resin, and a third ion exchange resin column filled with a mixed-phase ion exchange resin to obtain an ion-purified allulose-containing solution, The above mixed ion exchange resin is a mixture of a strongly acidic cation exchange resin and a weakly basic anion exchange resin. A method for purifying an allulose-containing solution, wherein the weakly basic anion exchange resin charged in the second ion exchange resin column and the weakly basic anion exchange resin constituting the mixed-bed ion exchange resin have an exchange capacity fraction of quaternary ammonium of 0 to 10%.

6. A method for purifying an allulose-containing solution, characterized in that the weakly basic anion exchange resin charged in the second ion exchange resin column in the fifth paragraph has an exchange capacity fraction of quaternary ammonium of 00%.

7. A method for purifying an allulose-containing solution, characterized in that the weakly basic anion exchange resin constituting the mixed phase ion exchange resin in paragraph 5 has an exchange capacity fraction of quaternary ammonium of 5 to 10%.

8. A method for purifying an allulose-containing solution, characterized in that in paragraph 5, the mixing volume ratio of the strongly acidic cation exchange resin and the weakly basic anion exchange resin constituting the mixed ion exchange resin is 1:1 to 1:

4.

9. A method for purifying an allulose-containing solution, characterized in that in paragraph 5, the volume ratio of the strongly acidic cation exchange resin filled in the first ion exchange resin column, the weakly basic anion exchange resin filled in the second ion exchange resin column, and the mixed-phase ion exchange resin filled in the third ion exchange resin column is 1:(0.5 to 2):(0.5 to 2).

10. A method for purifying an allulose-containing solution, characterized in that in paragraph 5, the allulose-containing solution injected into the first ion exchange resin column has a sugar solids concentration of 25 to 65 Brix, a pH of 3.5 to 5.5, an electrical conductivity of 20 to 400 ㎲ / cm, and an allulose content of 10 to 50% (w / w) based on the total solids weight.