Method for purifying allulose-containing solutions using ion exchange

Abstract

One embodiment of the present invention provides a method for purifying an allulose-containing solution, comprising passing the allulose-containing solution through an ion exchange resin column packed with a mixed-phase ion exchange resin to obtain an ion-purified allulose-containing solution. In this method, the mixed-phase ion exchange resin is a mixture of a strong acid cation exchange resin and a weak basic anion exchange resin, and the weak basic anion exchange resin constituting the mixed-phase ion exchange resin has a quaternary ammonium exchange capacity fraction of 0 to 10%. The method for purifying an allulose-containing solution according to the present invention can not only reduce the electrical conductivity of the allulose-containing solution to an acceptable level, but also minimize allulose loss by inhibiting the conversion of allulose to fructose or other substances by 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 production of high-quality allulose.

Description

[Technical Field]

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

[0002] D-allulose is an epimer of the 3-position carbon of fructose, and is also called D-psicose. Compared with cane sugar, D-allulose has a sweetness intensity of 70% (Oshima 2006), but only provides 0.3% of the energy, so it is a functional monosaccharide applicable as a low-calorie sweetener in diet foods (Matsuo et al. 2002). Furthermore, since D-allulose has the functions of inhibiting glucose absorption and blood glucose level, it can be applied to foods and drinks for diabetics, weight-loss foods and drinks, and the like. In addition, since it can inhibit the accumulation of abdominal fat by suppressing the enzyme activity involved in lipid synthesis in the liver, 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 characteristics described above, allulose is a good source that can replace sugar. However, because it is a rare sugar, a monosaccharide that exists very rarely in nature, an efficient method for producing allulose is necessary for its application in the food industry. The most efficient method for industrializing allulose production is to convert fructose to allulose using D-allulose 3-epimerase. The D-allulose-containing reaction product produced by the enzymatic reaction is then filtered, decolorized, concentrated, and purified by ion exchange to produce a low-purity solution with a D-allulose content of approximately 20-30% (w / w) on a solids basis. Furthermore, this low-purity solution with a D-allulose content of approximately 20-30% (w / w) is then processed by simulated moving bed (SMB) chromatography separation and ion exchange purification to produce a high-purity solution with a D-allulose content of approximately 95-99% (w / w) on a solids basis.

[0004] In relation to allulose purification technology, Registered Patent Publication No. 10-1988441 of the Republic of Korea discloses an allulose purification method that includes the steps of: mixing an allulose conversion reaction product with powdered activated carbon, performing a solid-liquid separation step on the mixture to remove impurities and activated carbon and obtain a filtrate; performing an ion purification step using a column packed with ion exchange resin after the activated carbon treatment step; and performing a pseudo-moving bed (SMB) chromatography separation step to obtain an allulose fraction and fructose raffinate. [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The present invention is derived from the prior art background, and its objective is to provide a method for purifying an allulose-containing solution that minimizes allulose loss while achieving an acceptable level of ion purification efficiency using an ion exchange resin. [Means for solving the problem]

[0006] When ion-exchange purification of a D-allulose-containing reaction product to produce a low-purity solution with a D-allulose content of approximately 20-30% (w / w) based on solid content, some of the allulose is converted to fructose and other substances by the active groups of the ion-exchange resin, resulting in allulose loss. Furthermore, when ion-exchange purification is performed after simulated moving bed (SMB) chromatography separation to produce a high-purity solution with a D-allulose content of approximately 95-99% (w / w) based on solid content, 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, allulose loss is very large. The inventors of the present invention recognized the unique problems that occur in the purification process of allulose-containing solutions using ion exchange, and in order to solve them, they conducted experiments purifying allulose-containing solutions with various combinations of ion-exchange resin columns. As a result, they confirmed that allulose loss is minimized when using a specific combination of ion-exchange resins, and thus completed the present invention.

[0007] To solve the aforementioned problems, an example of the present invention provides a method for purifying an allulose-containing solution, which includes the step of passing the allulose-containing solution through an ion exchange resin column packed with a multiphase ion exchange resin to obtain an ion-purified allulose-containing solution. In the method for purifying an allulose-containing solution according to an example of the present invention, the multiphase 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 multiphase ion exchange resin has an exchange capacity fraction of quaternary ammonium of 0 to 10%.

[0008] To solve the aforementioned problems, another example of the present invention provides a method for purifying an allulose-containing solution, comprising the steps of sequentially passing the allulose-containing solution through a first ion exchange resin column packed with a strongly acidic cation exchange resin, a second ion exchange resin column packed with a weakly basic anion exchange resin, and a third ion exchange resin column packed with a multiphase 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 multiphase ion exchange resin is a mixture of a strongly acidic cation exchange resin and a weakly basic anion exchange resin. Furthermore, in the method for purifying an allulose-containing solution according to another example of the present invention, the weakly basic anion exchange resin packed in the second ion exchange resin column and the weakly basic anion exchange resin constituting the multiphase ion exchange resin have an exchange capacity fraction of quaternary ammonium of 0 to 10%. [Effects of the Invention]

[0009] The method for purifying allulose-containing solutions according to the present invention not only reduces the electrical conductivity of the allulose-containing solution to an acceptable level, but also suppresses the conversion of allulose to fructose and other substances by the working groups of the ion exchange resin, thereby minimizing allulose loss. Therefore, the method for purifying allulose-containing solutions according to the present invention is suitable for mass production of high-quality allulose. [Modes for carrying out the invention]

[0010] The present invention will be described in detail below.

[0011] In this invention, the term "exchange capacity fraction" refers to the percentage of the total exchange capacity of an ion exchange resin that is contributed to by a specific exchange group.

[0012] The present invention relates to 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.

[0013] An example of a method for purifying an allulose-containing solution according to the present invention includes the step of passing the allulose-containing solution through an ion exchange resin column packed with a multiphase ion exchange resin to obtain an ion-purified allulose-containing solution. The multiphase ion exchange resin is a mixture of a strongly acidic cation exchange resin and a weakly basic anion exchange resin.

[0014] The type of strongly acidic cation exchange resin constituting the multiphase ion exchange resin is not particularly limited, and can be selected from, for example, hydrogen ion type (H type) or sodium type (Na type) strongly acidic cation exchange resins. When using the Na type strongly acidic cation exchange resin, it can be converted to the H type using an aqueous solution of an appropriate concentration of acid (e.g., HCl) before use. The strongly acidic cation exchange resin may be of gel type or porous type, and is preferably of porous type. The strongly acidic cation exchange resin may have sulfonic acid groups as exchange groups, and the base material may be a styrene-divinylbenzene copolymer produced by polymerizing a monovinylidene aromatic monomer (e.g., styrene) and a crosslinking agent (e.g., divinylbenzene (DVB)).

[0015] The type of weakly basic anion exchange resin constituting the multiphase ion exchange resin 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 of gel type or porous type, and is preferably of porous type. The weakly basic anion exchange resin may also have a tertiary amine group or a quaternary ammonium group as an exchange group, and the base material may be a styrene-divinylbenzene copolymer produced by polymerizing a monovinylidene aromatic monomer (e.g., styrene) and a crosslinking agent (e.g., divinylbenzene (DVB)). The quaternary ammonium group present in the weakly basic anion exchange resin is selected from a type I quaternary ammonium group such as trimethylammonium or a type II quaternary ammonium group such as dimethylethanolammonium, and is preferably a type I quaternary ammonium group such as trimethylammonium when considering purification efficiency and minimizing allulose loss. The weakly basic anion exchange resin constituting the multiphase ion exchange resin has a tertiary amine group as an exchange group, with an exchange capacity fraction of 100% for the tertiary amine group, when the exchange capacity fraction of quaternary ammonium is 0%. Furthermore, the weakly basic anion exchange resin constituting the multiphase ion exchange resin has a quaternary ammonium group and a tertiary amine group as exchange groups, with an exchange capacity fraction of 95% for the tertiary amine group, when the exchange capacity fraction of quaternary ammonium is 5%. Furthermore, the weakly basic anion exchange resin constituting the multiphase ion exchange resin has a quaternary ammonium group and a tertiary amine group as exchange groups, with an exchange capacity fraction of 90% for the tertiary amine group, when the exchange capacity fraction of quaternary ammonium is 10%. When considering ion purification efficiency, it is preferable that the exchange capacity fraction of quaternary ammonium in the weakly basic anion exchange resin constituting the multiphase ion exchange resin is 5-10%.

[0016] In a method for purifying an allulose-containing solution according to an example of the present invention, the mixed volume ratio of the strongly acidic cation exchange resin and the weakly basic anion exchange resin constituting the multiphase ion exchange resin is not particularly limited, and when considering ion purification efficiency and minimizing allulose loss, it is preferably 1:1 to 1:4, and more preferably 1:1.5 to 1:3.

[0017] In a method for purifying an allulose-containing solution according to an example of the present invention, the sugar solid content concentration, pH, electrical conductivity, allulose content, etc., of the allulose-containing solution injected into the ion exchange resin column are not particularly limited. When considering the ion purification efficiency, the allulose-containing solution preferably has a sugar solid content 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 weight of solids. More preferably, the sugar solid content concentration is 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 weight of solids.

[0018] In 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, when considering ion purification efficiency and minimizing allulose loss. Furthermore, in an example of the present invention, when the allulose-containing solution passes through the ion exchange resin column, the space velocity (SV) is not particularly limited, but is preferably 1 to 5, and more preferably 1.5 to 3, when considering ion purification efficiency.

[0019] Another example of the present invention provides a method for purifying an allulose-containing solution, which includes passing the allulose-containing solution sequentially through a first ion exchange resin column packed with a strongly acidic cation exchange resin, a second ion exchange resin column packed with a weakly basic anion exchange resin, and a third ion exchange resin column packed with a multiphase ion exchange resin to obtain an ion-purified allulose-containing solution.

[0020] In a method for purifying an allulose-containing solution according to another example of the present invention, the type of strongly acidic cation exchange resin packed into the first ion exchange resin column is not particularly limited and can be selected from, for example, hydrogen ion type (H type) or sodium type (Na type) strongly acidic cation exchange resins. When using the Na type strongly acidic cation exchange resin, it can be converted to the H type using an aqueous solution of an appropriate concentration of acid (e.g., HCl) before use. The strongly acidic cation exchange resin may be of gel type or porous type, and is preferably of gel type. The strongly acidic cation exchange resin may have a sulfonic acid group as an exchange group, and the base material may be a styrene-divinylbenzene copolymer produced by polymerizing a monovinylidene aromatic monomer (e.g., styrene) and a crosslinking agent (e.g., divinylbenzene (DVB)).

[0021] In another example of the present invention, in a method for purifying an allulose-containing solution, the type of weakly basic anion exchange resin packed into 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 of gel type or porous type, and is preferably of porous type. Furthermore, the weakly basic anion exchange resin may have a tertiary amine group or a quaternary ammonium group as an exchange group, and the base may be a styrene-divinylbenzene copolymer produced by polymerizing a monovinylidene aromatic monomer (e.g., styrene) and a crosslinking agent (e.g., divinylbenzene (DVB)). The quaternary ammonium group, which is the exchange group present in the weakly basic anion exchange resin, is selected from a type I quaternary ammonium group such as trimethylammonium or a type II quaternary ammonium group such as dimethylethanolammonium. When considering purification efficiency and minimizing allulose loss, a type I quaternary ammonium group such as trimethylammonium is preferred. When the exchange capacity fraction of quaternary ammonium is 0%, the weakly basic anion exchange resin has a tertiary amine group as an exchange group, with an exchange capacity fraction of 100% for the tertiary amine group. Furthermore, when the exchange capacity fraction of quaternary ammonium is 5%, the weakly basic anion exchange resin has both a quaternary ammonium group and a tertiary amine group as exchange groups, with an exchange capacity fraction of 95% for the tertiary amine group. Furthermore, when the exchange capacity fraction of quaternary ammonium is 10% of the weakly basic anion exchange resin, it has a quaternary ammonium group and a tertiary amine group as exchange groups, with the exchange capacity fraction of the tertiary amine group being 90%. When considering the ion purification efficiency and minimizing allulose loss, it is preferable that the weakly basic anion exchange resin packed into the second ion exchange resin column has a tertiary amine group as an exchange group and the exchange capacity fraction of quaternary ammonium is 0%.

[0022] In another example of the present invention, the multiphase ion exchange resin packed into 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 multiphase ion exchange resin has an exchange volume fraction of quaternary ammonium of 0 to 10%, and it is preferable that the exchange volume fraction of quaternary ammonium is 5 to 10% when considering ion purification efficiency and minimizing allulose loss. Furthermore, it is preferable that the mixed volume ratio of the strongly acidic cation exchange resin and the weakly basic anion exchange resin constituting the multiphase ion exchange resin is 1:1 to 1:4. In another example of the present invention, the technical features of the multiphase ion exchange resin packed into the third ion exchange resin column are the same as those described in the example of the present invention, so a detailed explanation is omitted.

[0023] In another example of the present invention, in a method for purifying an allulose-containing solution, 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 multiphase ion exchange resin packed in the third ion exchange resin column is not particularly limited, and when considering the 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).

[0024] In a method for purifying an allulose-containing solution according to another example of the present invention, there are no particular limitations on the saccharide solid content concentration, pH, electrical conductivity, allulose content and the like of the allulose-containing solution injected into the first ion exchange resin column. When considering the efficiency of ion purification, the allulose-containing solution preferably has a saccharide solid content 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 weight of the solid content. More preferably, the saccharide solid content concentration is 40 to 60 Brix, the pH is 4 to 5, the electrical conductivity is 50 to 250 μs / cm, and the allulose content is 15 to 35% (w / w) based on the total weight of the solid content.

[0025] In a method for purifying an allulose-containing solution according to another example of the present invention, when considering ion purification efficiency and minimization of allulose loss, the temperatures of the first ion exchange resin column, the second ion exchange resin column and the third ion exchange resin column are preferably 30 to 55°C, more preferably 35 to 45°C. 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 particularly limited. When considering the efficiency of ion purification, the space velocity is preferably 1 to 5, more preferably 1.5 to 3.

[0026] Hereinafter, the present invention will be described more specifically through examples. However, the following examples are only for clearly illustrating the technical features of the present invention, and are not intended to limit the protection scope of the present invention.

[0027] 1. Information on ion exchange resins The following Table 1 summarizes the information on ion exchange resins used in the examples of the present invention. All ion exchange resin products described in the following Table 1 are commercially available.

[0028]

Table 1

[0029] 2. Ion exchange purification of allulose-containing solution Experimental Example 1. A fructose solution was brought into contact with an immobilized allulose epimerase to carry out an isomerization reaction. Activated carbon was then added to the reaction product solution, and a decolorization reaction was carried out at 50°C. The solution was then filtered and concentrated to prepare a low-purity allulose-containing solution with a sugar solids concentration of approximately 50 Brix, a pH of approximately 4.5, and an electrical conductivity of approximately 10⁸ μs / cm. The allulose content in this low-purity allulose-containing solution was approximately 20.44% (w / w) based on the total weight of solids. A multiphase ion exchange resin was produced 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. Subsequently, a first column packed with a strongly acidic cation exchange resin (product name: DS1), a second column packed with a weakly basic anion exchange resin (product name: DS5), and a third column packed with a multiphase ion exchange resin were sequentially linked together to prepare a total of three ion exchange resin columns. The volume ratio of the cation exchange resin packed in the first column, the anion exchange resin packed in the second column, and the mixed ion exchange resin packed in the third column was 1:1.5:1. Then, the temperature of the ion exchange resin columns was maintained at 45°C, and a low-purity allulose-containing solution was passed through the ion exchange resin columns at a space velocity (SV) of 2.6 to obtain an ion-purified allulose-containing solution.

[0030] Experimental Example 2. A fructose solution was brought into contact with an immobilized allulose epimerase to carry out an isomerization reaction. Activated carbon was then added to the reaction product solution, and a decolorization reaction was carried out at 50°C. The solution was then filtered and concentrated to prepare a low-purity allulose-containing solution with a sugar solids concentration of approximately 50 Brix, a pH of approximately 4.5, and an electrical conductivity of approximately 118 μs / cm. The allulose content in the low-purity allulose-containing solution was approximately 20.30% (w / w) based on the total weight of solids. A strongly acidic cation exchange resin (product name: DS2) and a weakly basic anion exchange resin (product name: DS4) were mixed in a 1:2 volume ratio to produce a multiphase ion exchange resin. Subsequently, a first column packed with a strongly acidic cation exchange resin (product name: DS1), a second column packed with a weakly basic anion exchange resin (product name: DS4), and a third column packed with a multiphase ion exchange resin were sequentially linked together to prepare a total of three ion exchange resin columns. The volume ratio of the cation exchange resin packed in the first column, the anion exchange resin packed in the second column, and the mixed ion exchange resin packed in the third column was 1:1.5:1. Then, the temperature of the ion exchange resin columns was maintained at 45°C, and a low-purity allulose-containing solution was passed through the ion exchange resin columns at a space velocity (SV) of 2.6 to obtain an ion-purified allulose-containing solution.

[0031] Experimental Example 3. A fructose solution was brought into contact with an immobilized allulose epimerase to carry out an isomerization reaction. Activated carbon was then added to the reaction product solution, and a decolorization reaction was carried out at 50°C. After filtration and concentration, a low-purity allulose-containing solution was prepared with a sugar solids concentration of approximately 50 Brix, a pH of approximately 4.4, and an electrical conductivity of approximately 101 μs / cm. The allulose content in the low-purity allulose-containing solution was approximately 20.41% (w / w) based on the total weight of solids. A multiphase ion exchange resin was produced 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. Subsequently, a first column packed with a strongly acidic cation exchange resin (product name: DS1), a second column packed with a moderately basic anion exchange resin (product name: DS3), and a third column packed with a multiphase ion exchange resin were sequentially linked together to prepare a total of three ion exchange resin columns. The volume ratio of the cation exchange resin packed in the first column, the anion exchange resin packed in the second column, and the mixed ion exchange resin packed in the third column was 1:1.5:1. Then, the temperature of the ion exchange resin columns was maintained at 45°C, and a low-purity allulose-containing solution was passed through the ion exchange resin columns at a space velocity (SV) of 2.6 to obtain an ion-purified allulose-containing solution.

[0032] Experimental Example 4. A fructose solution was brought into contact with an immobilized allulose epimerase to carry out an isomerization reaction. Activated carbon was then added to the reaction product solution, and a decolorization reaction was carried out at 50°C. The solution was then filtered and concentrated to prepare a low-purity allulose-containing solution with a sugar solids concentration of approximately 50 Brix, a pH of approximately 4.5, and an electrical conductivity of approximately 105 μs / cm. The allulose content in this low-purity allulose-containing solution was approximately 20.39% (w / w) based on the total weight of solids. A strongly acidic cation exchange resin (product name: DS2) and a strongly basic anion exchange resin (product name: DS6) were mixed in a 1:2 volume ratio to produce a multiphase ion exchange resin. Then, a first column packed with a strongly acidic cation exchange resin (product name: DS1), a second column packed with a moderately basic anion exchange resin (product name: DS3), and a third column packed with a multiphase ion exchange resin were sequentially linked together to prepare a total of three ion exchange resin columns. The volume ratio of the cation exchange resin packed in the first column, the anion exchange resin packed in the second column, and the mixed ion exchange resin packed in the third column was 1:1.5:1. Then, the temperature of the ion exchange resin columns was maintained at 45°C, and a low-purity allulose-containing solution was passed through the ion exchange resin columns at a space velocity (SV) of 2.6 to obtain an ion-purified allulose-containing solution.

[0033] Experimental Example 5. A fructose solution was contacted with an immobilized allulose epimerase to promote an isomerization reaction. Activated carbon was then added to the reaction product solution, and a decolorization reaction was carried out at 50°C. Following filtration, concentration, and ion exchange resin purification, a low-purity allulose-containing solution was obtained. Subsequently, the low-purity allulose-containing solution was subjected to a pseudo-moving bed (SMB) chromatography separation process using a column packed with a cation exchange resin to which calcium-activated groups were attached. A high-purity allulose-containing solution was prepared with a sugar solids concentration of approximately 10 Brix, a pH of approximately 4.5, and an electrical conductivity of approximately 36 μs / cm. In this high-purity allulose-containing solution, the allulose content was approximately 97.96% (w / w) based on the total weight of solids. A multiphase ion exchange resin was produced by mixing a strongly acidic cation exchange resin (product name: DS2) and a weakly basic anion exchange resin (product name: DS4) in a 1:2 volume ratio. Next, an ion exchange resin column packed with multiphase ion exchange resin was prepared. Then, 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.

[0034] Experimental Example 6. A fructose solution was contacted with an immobilized allulose epimerase to promote an isomerization reaction. Activated carbon was then added to the reaction product solution, and a decolorization reaction was carried out at 50°C. Following filtration, concentration, and ion exchange resin purification, a low-purity allulose-containing solution was obtained. Next, a pseudo-mobile bed (SMB) chromatography separation process was performed on the low-purity allulose-containing solution using a column packed with a cation exchange resin to which calcium-activated groups were attached. A high-purity allulose-containing solution was prepared with a sugar solids concentration of approximately 10 Brix, a pH of approximately 4.5, and an electrical conductivity of approximately 40 μs / cm. In this high-purity allulose-containing solution, the allulose content was approximately 98.3% (w / w) based on the total weight of solids. A multiphase ion exchange resin was produced 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. Next, an ion exchange resin column packed with multiphase ion exchange resin was prepared. Then, 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.

[0035] Experimental Example 7. A fructose solution was contacted with an immobilized allulose epimerase to promote an isomerization reaction. Activated carbon was then added to the reaction product solution, and a decolorization reaction was carried out at 50°C. Following filtration, concentration, and ion exchange resin purification, a low-purity allulose-containing solution was obtained. Subsequently, the low-purity allulose-containing solution was subjected to a pseudo-moving bed (SMB) chromatography separation process using a column packed with a cation exchange resin to which calcium-activated groups were attached. A high-purity allulose-containing solution was prepared with a sugar solids concentration of approximately 10 Brix, a pH of approximately 4.5, and an electrical conductivity of approximately 36 μs / cm. In this high-purity allulose-containing solution, the allulose content was approximately 97.63% (w / w) based on the total weight of solids. A multiphase ion exchange resin was produced by mixing a strongly acidic cation exchange resin (product name: DS2) and a strongly basic anion exchange resin (product name: DS6) in a 1:2 volume ratio. Next, an ion exchange resin column packed with multiphase ion exchange resin was prepared. Then, 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.

[0036] Table 2 below summarizes the combinations of ion exchange resins used in Experimental Examples 1 to 7.

[0037] [Table 2]

[0038] Table 3 below summarizes the changes in the physical properties of the allulose-containing solution before injection into the ion exchange resin column and after it has passed through the ion exchange resin column and been discharged.

[0039] [Table 3]

[0040] As shown in Tables 2 and 3 above, the allulose-containing solution discharged after passing through the ion exchange resin column exhibited acceptable levels of pH and conductivity regardless of the combination of ion exchange resins. However, when the allulose-containing solution was ionically purified by passing through the ion exchange resin column, the allulose loss generated by isomerization reactions, etc., varied significantly depending on the combination of ion exchange resins. Specifically, allulose loss was minimized in Experimental Examples 1, 2, and 5. The ion exchange resin columns used in Experimental Examples 1, 2, and 5 all contained a multiphase ion exchange resin 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. On the other hand, the ion exchange resin column used in Experimental Example 3 also contained a multiphase ion exchange resin prepared by mixing a strongly acidic cation exchange resin (product name: DS2) and a weakly basic anion exchange resin (product name: DS4) in a 1:2 volume ratio, but the allulose loss in Experimental Example 3 was slightly larger. This result is attributable 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) with an exchange capacity fraction of quaternary ammonium accounting for 0% and a weakly basic anion exchange resin (product name: DS4) with an exchange capacity fraction of quaternary ammonium accounting for 5-10%, respectively. In contrast, in Experimental Example 3, the anion exchange resin located in the second stage was a moderately basic anion exchange resin (product name: DS3) with an exchange capacity fraction of quaternary ammonium accounting for 25%. The results showed that the allulose loss rate increased as the exchange capacity fraction of quaternary ammonium in the anion exchange resin located in the second stage of the ion exchange resin column increased. From the viewpoint of mass production, it is preferable that the exchange capacity fraction of quaternary ammonium in the anion exchange resin located in the second stage of the ion exchange resin column be between 0 and 10%.

[0041] Although the present invention has been described above through examples, the present invention is not necessarily limited thereto, and various modifications are possible without departing from the scope and spirit of the present invention. Therefore, the scope of protection of the present invention should be interpreted as including all embodiments belonging to the claims attached to the present invention. Furthermore, the present invention includes the following embodiments. [Aspect 1] A method comprising the step of passing an allulose-containing solution through an ion exchange resin column packed with a multiphase ion exchange resin to obtain an ion-purified allulose-containing solution, The multiphase 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, characterized in that the weakly basic anion exchange resin constituting the multiphase ion exchange resin has an exchange capacity fraction of quaternary ammonium of 0 to 10%. [Aspect 2] The method for purifying an allulose-containing solution according to Embodiment 1, characterized in that the weakly basic anion exchange resin constituting the multiphase ion exchange resin has an exchange capacity fraction of quaternary ammonium of 5 to 10%. [Aspect 3] The method for purifying an allulose-containing solution according to Embodiment 1, characterized in that the mixed volume ratio of the strongly acidic cation exchange resin and the weakly basic anion exchange resin constituting the multiphase ion exchange resin is 1:1 to 1:4. [Aspect 4] A method for purifying an allulose-containing solution according to any one of embodiments 1 to 3, characterized in that the allulose-containing solution injected into the ion-exchange resin column has a sugar solid content 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 weight of solids. [Aspect 5] A method comprising the step of sequentially passing an allulose-containing solution through a first ion exchange resin column packed with a strongly acidic cation exchange resin, a second ion exchange resin column packed with a weakly basic anion exchange resin, and a third ion exchange resin column packed with a multiphase ion exchange resin to obtain an ion-purified allulose-containing solution, The multiphase 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, characterized in that the weakly basic anion exchange resin packed in the second ion exchange resin column and the weakly basic anion exchange resin constituting the multiphase ion exchange resin have an exchange volume fraction of quaternary ammonium of 0 to 10%. [Aspect 6] The method for purifying an allulose-containing solution according to embodiment 5, characterized in that the weakly basic anion exchange resin packed in the second ion exchange resin column has an exchange volume fraction of quaternary ammonium of 0%. [Aspect 7] The method for purifying an allulose-containing solution according to embodiment 5, characterized in that the weakly basic anion exchange resin constituting the multiphase ion exchange resin has an exchange capacity fraction of quaternary ammonium of 5 to 10%. [Aspect 8] The method for purifying an allulose-containing solution according to embodiment 5, characterized in that the mixed volume ratio of the strongly acidic cation exchange resin and the weakly basic anion exchange resin constituting the multiphase ion exchange resin is 1:1 to 1:4. [Aspect 9] The method for purifying an allulose-containing solution according to Embodiment 5, characterized in that 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 multiphase ion exchange resin packed in the third ion exchange resin column is 1:(0.5~2):(0.5~2). [Aspect 10] The method for purifying an allulose-containing solution according to Embodiment 5, characterized in that the allulose-containing solution injected into the first ion exchange resin column has a sugar solid content 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 weight of solids.

Claims

1. A method for purifying an allulose-containing solution, comprising the step of passing the allulose-containing solution through an ion-exchange resin column packed with a multiphase ion-exchange resin to obtain an ion-purified allulose-containing solution, The aforementioned multiphase 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 aforementioned multiphase ion exchange resin has an exchange capacity fraction of quaternary ammonium of 5 to 10%. The mixed volume ratio of the strongly acidic cation exchange resin and the weakly basic anion exchange resin constituting the multiphase ion exchange resin is 1:1.5 to 1:

3. A method for purifying an allulose-containing solution, characterized in that the allulose-containing solution injected into the ion-exchange resin column has a sugar solid content concentration of 8 to 30 Brix, a pH of 4.0 to 5.5, an electrical conductivity of 15 to 60 μs / cm, and an allulose content of 90 to 99% (w / w) based on the total weight of solids.

2. The method for purifying an allulose-containing solution according to Claim 1, characterized in that the strongly acidic cation exchange resin constituting the multiphase ion exchange resin is of gel type.

3. A method for purifying an allulose-containing solution, comprising the steps of sequentially passing the allulose-containing solution through a first ion exchange resin column packed with a strongly acidic cation exchange resin, a second ion exchange resin column packed with a weakly basic anion exchange resin, and a third ion exchange resin column packed with a multiphase ion exchange resin to obtain an ion-purified allulose-containing solution, wherein The aforementioned multiphase 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 packed into the second ion exchange resin column has an exchange volume fraction of quaternary ammonium of 0%. The weakly basic anion exchange resin constituting the aforementioned multiphase ion exchange resin has an exchange capacity fraction of quaternary ammonium of 5 to 10%. The mixed volume ratio of the strongly acidic cation exchange resin and the weakly basic anion exchange resin constituting the multiphase ion exchange resin is 1:1.5 to 1:

3. 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 multiphase ion exchange resin packed in the third ion exchange resin column is 1:(0.65-1.5):(0.65-1.5). A method for purifying an allulose-containing solution, characterized in that the allulose-containing solution injected into the first ion-exchange resin column has a sugar solid content concentration of 40 to 60 Brix, a pH of 4.0 to 5.5, an electrical conductivity of 50 to 250 μs / cm, and an allulose content of 10 to 50% (w / w) based on the total weight of solids.

4. The strongly acidic cation exchange resin packed into the first ion exchange resin column is of gel type, The method for purifying an allulose-containing solution according to claim 3, characterized in that the strongly acidic cation exchange resin constituting the multiphase ion exchange resin is of the porous type.

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