JPS6351000B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses a fixed bed packed with a strongly acidic cation exchange resin of alkali metal type or alkaline earth metal type to convert fructose into sucrose with 1 to 4
The purpose of this method is to separate oligosaccharides with high purity and high yield from a mixture of molecularly bonded oligosaccharides of trisaccharides or higher and saccharides of disaccharides or lower. The production of insoluble dextran is considered to be the main cause of dental caries, but oligosaccharides of trisaccharides or higher (hereinafter referred to as oligosaccharides), such as 1 to 4 molecules of fructose bound to sucrose, are produced by Streptococcus mutans. It is attracting attention as a sweetener because it is not only not affected by the action of dextran eucrase produced by oral microorganisms, but also has the effect of suppressing the production of insoluble dextran from sucrose by dextran eucrase. The oligosaccharide is contained in a transferred sugar composition obtained by allowing fructosyltransferase to act on sucrose, but in addition to the oligosaccharide, unreacted sucrose and by-products due to the transfer reaction are also included in the transferred sugar composition. It contains impurities such as disaccharides or monosaccharides such as raw glucose and fructose, and therefore it is necessary to purify the transferred sugar composition in order to obtain highly pure oligosaccharides. Against this background, the present inventors conducted extensive research using chromatographic separation techniques to separate high-purity oligosaccharides from a mixture of oligosaccharides and the aforementioned disaccharides and monosaccharides. Alternatively, it has been found that the oligosaccharide of high purity can be separated by chromatographic separation using a circulation system using an alkaline earth metal type strongly acidic cation exchange resin. That is, the present invention performs chromatographic separation by passing a mixed stock solution of oligosaccharides, disaccharides, and monosaccharides in a downward or upward flow through a fixed bed filled with a strongly acidic cation exchange resin of alkali metal type or alkaline earth metal type. When separating oligosaccharides and other sugars using this method, a specified amount of stock solution and a specified amount of water are passed in the order of stock solution and water, and the effluent is returned to the packed bed in the order of flow, at least 2 times.
A preceding step of circulating for more than one cycle is carried out, and after the circulation of the preceding step, an oligosaccharide solution, a mixture of oligosaccharides and a disaccharide/monosaccharide solution, and a disaccharide/monosaccharide solution are flowed out in this order from the outflow port. Only a specified amount of relatively pure oligosaccharide liquid portion and a specified amount of relatively pure disaccharide/monosaccharide liquid portion are taken out of the system, while the other liquids are circulated again in the order of flow. , a specified amount of the stock solution is injected into the circulating fluid, which is a mixture of oligosaccharides and disaccharides/monosaccharides, while a specified amount of water is injected into the circulating fluid, which is a disaccharide/monosaccharide mixture with a relatively low concentration. After the inflow of the liquid, a steady process is carried out in which the total volume of the stock solution and water to be injected is made equal to the total volume of the oligosaccharide solution and the disaccharide/monosaccharide solution taken out of the system. The present invention relates to a method for separating oligosaccharides in which 1 to 4 molecules of fructose are bound to sucrose, which is characterized in that an oligosaccharide solution and a disaccharide/monosaccharide solution are sequentially taken out by repeating the steps. Hereinafter, an example of an embodiment of the present invention will be described in detail using the drawings. FIG. 1 is an explanatory diagram showing the flow of the oligosaccharide separation apparatus, in which one end of the inflow pipe 3 is connected to the upper end of the separation column 2 filled with a strongly acidic cation exchange resin 1 of the alkali metal type or alkaline earth metal type. The other end is connected to the pump 4. Also, one end of the outflow pipe 5 is connected to the lower end of the separation column 2, and the other end is connected to the outflow branch pipe 5a,
5b, 5c, 5d, 5e, 5f, 5g, and 5h, respectively. Dilute oligosaccharide liquid tank 6, oligosaccharide liquid tank 7, oligosaccharide rich (1) liquid tank 8, oligosaccharide rich (2) liquid tank 9, disaccharide/monosaccharide rich (1) liquid tank 10, disaccharide/monosaccharide rich (1) liquid tank 10, Sugar rich (2) liquid tank 11, disaccharide/monosaccharide liquid tank 1
2. A dilute disaccharide/monosaccharide liquid tank 13 is installed, and the effluent from the outflow branch pipe 5a is sent to the dilute oligosaccharide liquid tank 6, the outflow from the outflow branch pipe 5b is sent to the oligosaccharide liquid tank 7,
As shown in FIG. 1, the outflow branch pipes 5c to 5h are configured to flow into each tank in sequence as shown in FIG. On the other hand, dilute oligosaccharide liquid tank 6, oligosaccharide liquid tank 7, oligosaccharide rich (1) liquid tank 8, oligosaccharide rich (2) liquid tank 9, disaccharide/monosaccharide rich (1) liquid tank 10, disaccharide・Monosaccharide rich (2) liquid tank 11, disaccharide/monosaccharide liquid tank 1
2. Connect one end of the suction pipes 14a to 14h to the lower part of each tank of the dilute disaccharide/monosaccharide liquid tank 13, respectively, and connect the other ends of all the suction pipes to the suction main pipe 15. It communicates with the pump 4. Stock solution tank 16
At the same time, one end of the introduction pipe 18a is connected to the lower part of the stock solution tank 16, and one end of the introduction pipe 18b is connected to the lower part of the water tank 17, and the other end of these introduction pipes is connected to the suction main pipe. Connect to 15. Further, an oligosaccharide liquid extraction pipe 19 is branched and attached to the suction pipe 14b, and a disaccharide/monosaccharide liquid extraction pipe 20 is branched and attached to the suction pipe 14g. The number of oligosaccharide rich liquid tanks 8, 9 and disaccharide/monosaccharide rich liquid tanks 10, 11 may be further increased as necessary. Using the oligosaccharide separation device constructed in this way, oligosaccharide liquid and disaccharide/disaccharide are separated from the stock solution.
In separating the monosaccharide solution, in the present invention, first, a specified amount of stock solution and a specified amount of water are passed through in the order of stock solution and water, and the effluent is circulated through the packed bed again in the order in which it flows out for at least two cycles or more. Perform the preliminary process. That is, a specified amount of the stock solution is poured into the stock solution tank 1 from the upper part of the separation column 2 in which some water layer is formed above the packed bed of the strongly acidic cation exchange resin 1.
6 using the pump 4, and then, when the prescribed amount of the stock solution has finished flowing in, a prescribed amount of water is successively introduced from the water tank 17 using the pump 4. On the other hand, the effluent is discharged from the lower part of the separation column 2 at the same time as the raw solution and water are introduced. After the water has flowed out,
The effluent is separated to some extent into an oligosaccharide liquid part P and a disaccharide/monosaccharide liquid part Q as shown in FIG. ,5d,5e,5f,5g,5
The liquids that flow out using h are diluted oligosaccharide liquid tank 6, oligosaccharide liquid tank 7, oligosaccharide rich (1) liquid tank 8, oligosaccharide rich (2) liquid tank 9, and disaccharide/monosaccharide rich liquid tank 9.
(1) Liquid tank 10, disaccharide/monosaccharide rich (2) Liquid tank 11, disaccharide/monosaccharide liquid tank 12, dilute disaccharide/monosaccharide liquid tank 13. After the liquid of each portion is received in each tank in this way, the liquid of each of these portions is then allowed to flow back into the separation column 2 in the order in which it was discharged and circulated. That is, using the pump 4, the liquid in the dilute oligosaccharide liquid tank 6 is first introduced from the upper part of the separation column 2 through the suction pipe 14a, and then the liquid in the dilute oligosaccharide liquid tank 7,
Oligosaccharide rich (1) liquid tank 8, oligosaccharide rich (2) liquid tank 9, disaccharide/monosaccharide rich (1) liquid tank 10, disaccharide/monosaccharide rich (2) liquid tank 11, disaccharide/monosaccharide rich (2) liquid tank 11, Each liquid in the sugar liquid tank 12 and the dilute disaccharide/monosaccharide liquid tank 13 is passed through the suction pipe 14 in the order of flow.
b, 14c, 14d, 14e, 14f, 14g,
14 h, and the liquid is made to flow in from the upper part of the separation column 2 one after another, and the effluent is again received into each tank in the order of outflow. If the above-mentioned circulation is repeated, for example, for three cycles, the concentration distribution of the effluent from the first cycle shown in Figure 2 will change to the concentration distribution of the effluent from the third cycle shown in Figure 3. The concentration curves of the liquid part P and the disaccharide/monosaccharide liquid part Q gradually diverge. In other words, there is a difference in the adsorption power of oligosaccharides and disaccharides/monosaccharides to the strongly acidic cation exchange resin, so oligosaccharides flow out first, followed by disaccharides/monosaccharides, but they flow out from the separation column. When the above-mentioned circulation is performed in which the effluent flows in again in the order in which it flows out, the outflow of disaccharides and monosaccharides is slower than that of oligosaccharides, and the separation of both sugars becomes clearer. This indicates that the distance between the oligosaccharide adsorption zone and the disaccharide/monosaccharide adsorption zone formed while moving in the packed bed was amplified. In the present invention, the distance between the oligosaccharide adsorption zone and the disaccharide/monosaccharide adsorption zone can be amplified by performing the preceding process of circulating the effluent as described above, so that high purity can be achieved in the subsequent regular process. It is possible to separate oligosaccharides of For example, when obtaining an oligosaccharide solution and a disaccharide/monosaccharide solution from the effluent in the third cycle after circulation, the oligosaccharide solution and the disaccharide/monosaccharide solution are sequentially taken out by carrying out the steady process described below. The outflow of each liquid in the third cycle is as shown in Figure 3. Part A of the dilute oligosaccharide that flows out first goes to the dilute oligosaccharide liquid tank 6, and the next relatively high-purity oligosaccharide is transferred to the dilute oligosaccharide liquid tank 6. Part A of the liquid is transferred to the oligosaccharide liquid tank 7, and the next oligosaccharide rich (1)
Part C of the liquid goes to oligosaccharide rich (1) liquid tank 8, and part E of the next oligosaccharide rich (2) liquid tank goes to oligosaccharide rich (2).
To liquid tank 9, the next disaccharide/monosaccharide rich (1) liquid part O goes to disaccharide/monosaccharide rich (1) liquid tank 10, the next disaccharide/monosaccharide rich (2) liquid part The liquid goes to the disaccharide/monosaccharide rich (2) liquid tank 11, the next relatively high-purity disaccharide/monosaccharide liquid part goes to the disaccharide/monosaccharide liquid tank 12, and finally the diluted sugar liquid is discharged. Partial portions of the disaccharide and monosaccharide solutions are separately collected into the diluted disaccharide and monosaccharide solution tanks 13, so the oligosaccharide solution in the oligosaccharide solution tank 7 is separated using the oligosaccharide solution take-out tube 19. Take it out of the system, and also disaccharide and
Disaccharide/monosaccharide liquid tank 1 using monosaccharide liquid take-out tube 20
Part of the disaccharide/monosaccharide solution in step 3 is taken out of the system.
On the other hand, the effluents from the other tanks are again circulated in the order of their outflow using the pump 4, and at this time, a specified amount of the stock solution and a specified amount of water are injected spot-wise into the portions described below. In other words, the circulation in the steady process is
Effluent in dilute oligosaccharide liquid tank 6, then oligosaccharide rich (1) Effluent in liquid tank 8, then oligosaccharide rich (2)
The effluent in the liquid tank 9 is made to flow into the separation column 2 using the pump 4 in order, and then a specified amount of the stock solution is transferred to the stock tank 16.
The pump 4 is used to make the water flow in from the water. After injecting a specified amount of the stock solution, the effluent in the disaccharide/monosaccharide rich (1) liquid tank 10, then the effluent in the disaccharide/monosaccharide rich (2) liquid tank 11, and then the diluted disaccharide/monosaccharide rich (2) liquid in the liquid tank 11. The effluent in the sugar solution tank 13 is made to flow in in this order, and then a prescribed amount of water is made to flow in from the water tank 17 using the pump 4. On the other hand, the effluent flowing out from the separation tower 2 is as shown in Fig. 3.
It is divided into parts A, C, E, O, F, K, and K, respectively, and each of these effluents is poured into tanks 6, 7,
It is received in each tank 8, 9, 10, 11, 12, and 13 in order. Thereafter, the oligosaccharide solution and the disaccharide/monosaccharide solution are sequentially taken out through a regular process in which the extraction of the oligosaccharide solution, the disaccharide/monosaccharide solution, and the pouring out of the stock solution and water are repeated in the same manner. The present invention first performs the preceding step as explained above, and then repeats the steady-state steps sequentially, thereby making it possible to sequentially extract a high-purity oligosaccharide solution and a high-purity disaccharide/monosaccharide solution at relatively high yields. It is possible. In this case, oligosaccharides,
It is necessary not to disturb the flow curves of disaccharides and monosaccharides, and the concentration distribution of oligosaccharides, disaccharides, and monosaccharides, such as that formed in Figure 3 during the steady process, must be reproduced in order from now on. It is necessary to do so. In the present invention, this is achieved by three technical means as explained below. First, when circulating the effluent from the separation column 2 through the preceding process and the steady process, the effluent should flow into the separation column 2 in the order in which the effluents are discharged. Second, the injection of the stock solution in the steady-state process is carried out in spots after the injection of the oligosaccharide-rich solution in the circulating fluid. Specifically, as mentioned above, the stock solutions are the circulating fluid oligosaccharide rich solution (2) (part E in Figure 3) and disaccharide/monosaccharide rich solution (2) (part O in Figure 3). As shown in FIG.
In other words, this is the part that most closely approximates the composition of the stock solution, and by injecting the stock solution into this part of the circulating fluid, it is possible to minimize the disturbance imparted to the adsorption zone of each sugar. Third, the oligosaccharide solution, disaccharide, and
The goal is to match the total of the monosaccharide solution. Only by making full use of the three technical means described above will it be possible to obtain a highly purified oligosaccharide solution with an oligosaccharide content of 80% or more in a high yield. To explain the circulation in the preceding step of the present invention, as the circulation continues, the concentration curves of oligosaccharides and disaccharides/monosaccharides change as shown in FIGS. 2 and 3, and the oligosaccharide moiety P and The disaccharide and monosaccharide portion Q become separated, but at the same time, the concentration of each sugar in the effluent also decreases. Therefore, if the circulation is repeated too many times, the sugar concentration will drop too much, which is not preferable, and the number of circulation should usually be about 3 to 5 cycles. Next, the inflow amounts of the stock solution and water during the preceding step in the present invention, the injection amounts of the circulating fluid, stock solution, and water during the steady step, and the outflow amounts of the oligosaccharide solution and the disaccharide/monosaccharide solution will be explained. First, the flow rate of the stock solution in the preceding process is 0.1~
The ratio is preferably 0.5/- resin (ion exchange resin), and within this range, the more the stock solution is allowed to flow in, the higher the concentration of oligosaccharides obtained in the regular process can be. However, if the amount of resin exceeds 0.5/-, the separation efficiency will decrease, which is not preferable.
The amount of inflow of the next water is roughly proportional to the amount of inflow of the stock solution.
A ratio of 0.1 to 0.7/-resin is good; if more than this flow in, the oligosaccharide will be diluted more than necessary, which is not preferable. The amount of each liquid received into each tank during the steady process, the amount of stock solution, and the amount of water injected are 0.03 to 0.1 for the dilute oligosaccharide solution in Figure 3.
/-resin, preferably around 0.05/-resin, into the dilute oligosaccharide liquid tank 6, and in the following order, parts of the oligosaccharide solution are 0.1-0.2/-resin, preferably around 0.1/-resin, oligosaccharide-rich ( 1)
Part C of the liquid is 0.1 to 0.2/- resin, preferably
Before and after 0.14/- resin, the partial ratio of oligosaccharide rich (2) solution is 0.1 to 0.2/- resin, preferably 0.14
/- before and after resin, partial ratio of disaccharide/monosaccharide rich (1) solution is 0.07 to 0.15/- resin, preferably 0.1/
−The partial power of the disaccharide/monosaccharide rich (2) solution before and after the resin is
0.07-0.15/- resin, preferably 0.1/-
Before and after the resin, the partial value of the disaccharide/monosaccharide solution is 0.1 to 0.3/
-Resin, preferably 0.2/- around resin, and partial weight of dilute disaccharide/monosaccharide solution is 0.05 to 0.2/-
-resin, preferably around 0.1/-resin, in each tank. The amount of stock solution to be injected is usually 0.05 to 0.2/- resin, preferably around 0.1/- resin, and the amount of water is usually 0.15 to 0.4/- resin, preferably 0.2
/- It is preferable to set it before and after the resin. Note that part A of the dilute oligosaccharide solution may be included in part B of the oligosaccharide solution, and part H of the dilute disaccharide/monosaccharide solution may be included in part K of the disaccharide/monosaccharide solution. The strongly acidic cation exchange resin used in the present invention is preferably porous, and the finer the particle size, the better from the viewpoint of separability. However, if it is too fine, in the case of industrial equipment, the pressure loss will be large and cause liquid flow to be impossible or one-sided flow.
Use 200 mesh (wet). In addition, the stock solution should have a total oligosaccharide content of 20% or more, usually around 50%, and a sugar solution concentration of 35 to 60%. Note that the liquid passing temperature is preferably 60 to 70°C from the viewpoints of pressure loss during liquid passing, prevention of microbial contamination, and stability of oligosaccharides. In the present invention, an alkali metal form such as a sodium form or an alkaline earth metal form such as a calcium form is used, but in the case of an alkaline earth metal form, the latter half of the outflow curve of the disaccharide/monosaccharide liquid part Q is extended. The sodium form is preferred as it tends to increase the separation time and therefore requires a slightly longer separation time. However, chromatographic separation in the sodium form has the disadvantage that the yield of oligosaccharides decreases slightly as the cycle continues. The inventors investigated the cause of this decrease in yield and found that as the cycle continued, a portion of the sodium-form resin became hydrogen-form, and this hydrogen-form resin hydrolyzed a portion of the oligosaccharide. did. Therefore, in order to prevent this hydrolysis, it is desirable to perform the following operations. That is, a small amount of an alkali metal hydroxide, alkaline earth hydroxide, or alkali salt of an alkali metal or alkaline earth metal, such as sodium hydroxide, calcium hydroxide, sodium carbonate, sodium acetate, etc., is added to the stock solution or water; It is preferable to make the stock solution or water alkaline and pass it through a strongly acidic cation exchange resin. By making the stock solution or water alkaline in this way, the generation of hydrogen resin can be prevented. In addition, before or after chromatographic separation, a strongly acidic cation exchange resin is added with an alkali metal hydroxide, an alkaline earth metal hydroxide, or an alkali or neutral salt of an alkali metal or alkaline earth metal, such as sodium hydroxide, hydroxide, etc. A hydrogen form resin produced by periodically passing an aqueous solution of calcium oxide, sodium carbonate, sodium acetate, sodium chloride, calcium chloride, etc., may be converted into an alkali metal form or an alkaline earth metal form. Examples of the present invention will be described below. Example: Strongly acidic cation exchange resin XT-1007 (manufactured by Tokyo Organic Chemical Industry Co., Ltd.) with a particle size of 40 to 80 mesh was used.
A 49.4 mm, 6 m high column was packed with 11.5, and the IN
- Sodium chloride solution 3/- The resin was passed through to completely regenerate it into the sodium form. Next, this resin has a stock solution concentration of 50%, a content ratio of oligosaccharides in which 1 to 4 molecules of fructose are bound to sucrose 48%, a disaccharide/monosaccharide content ratio of 52%, and a sugar solution containing 0.01 mol/sodium acetate of 2.76%. was passed in a downward flow at a temperature of 60°C and a flow SV of 0.2, and water containing 0.001 mol of sodium hydroxide/7.59 was added.
Water was passed through. Next, the effluent flowing out was collected in fractions of 0.05/-resin, and the fractions were sequentially passed from the top of the column in the order in which they were collected, and three cycles were repeated. Figure 4 shows the state of separation of oligosaccharides, disaccharides, and monosaccharides in the effluent of the third cycle. That is, each fraction was divided into dilute oligosaccharide solution, oligosaccharide solution, oligosaccharide rich solution, disaccharide/monosaccharide rich solution, disaccharide/monosaccharide solution, and dilute disaccharide/monosaccharide solution. Next, 1.73 of the oligosaccharide solution (186 g of oligosaccharide,
Disaccharides/monosaccharides 7g) and 3 fractions of disaccharides/monosaccharides with fraction numbers No. 50 to 52 1.73 (oligosaccharides 20
g, 224 g of disaccharides and monosaccharides) were taken out of the system and replaced with a stock solution of 0.71 (210 g of oligosaccharides, 227 g of disaccharides and monosaccharides) to which 0.01 mol of sodium acetate was added.
2.75 ml of water to which 0.001 mol of NaOH was added was injected and the circulation continued again. That is, injection is performed in the order of dilute oligosaccharide solution, oligosaccharide rich solution, stock solution, disaccharide/monosaccharide rich solution, dilute disaccharide/monosaccharide solution, and water, and from the next cycle, the sugar solution is extracted every cycle. Separation of oligosaccharides was carried out by performing injections. Table 1 shows the average sugar composition of the oligosaccharide solution and the disaccharide/monosaccharide solution taken out of the system. 【table】

[Brief explanation of drawings]

Each of the drawings shows an example of the embodiment of the present invention, and FIG. 1 is an explanatory diagram showing the flow of the method for separating oligosaccharides, and FIGS. It shows the concentration distribution of disaccharides and monosaccharides, where the vertical axis represents the sugar concentration and the horizontal axis represents the outflow time. Figure 2 shows the concentration in the first cycle of circulation, and Figure 3 shows the concentration in the third cycle of circulation. It is a graph of distribution. Moreover, FIG. 4 is a graph showing the concentration distribution of oligosaccharides, disaccharides, and monosaccharides in the effluent of the third cycle of circulation in the example, where the vertical axis represents the sugar concentration and the horizontal axis represents each fraction number. . DESCRIPTION OF SYMBOLS 1... Strongly acidic cation exchange resin, 2... Separation column, 3... Inflow pipe, 4... Pump, 5... Outflow pipe, 6... Dilute oligosaccharide liquid tank, 7... Oligosaccharide liquid tank, 8 ... Oligosaccharide rich (1) liquid tank, 9 ... Oligosaccharide rich (2) liquid tank, 10 ... Disaccharide/monosaccharide rich (1) liquid tank, 11 ... Disaccharide/monosaccharide rich (2) Liquid tank, 12...
Disaccharide/monosaccharide liquid tank, 13... Dilute disaccharide/monosaccharide liquid tank,
14... Suction pipe, 15... Suction main pipe, 16... Stock solution tank, 17... Water tank, 18... Stock solution, water introduction pipe,
19... Oligosaccharide liquid removal tube, 20... Disaccharide.
Monosaccharide solution extraction tube.

Claims (1)

[Scope of Claims] 1. A mixed stock solution of oligosaccharides of trisaccharides or higher and saccharides of disaccharides or lower is flowed downward or upward through a fixed bed filled with strongly acidic cation exchange resin of alkali metal type or alkaline earth metal type. When separating oligosaccharides of trisaccharides or higher and sugars of disaccharides or lower using a chromatographic separation method, a specified amount of the stock solution and a specified amount of water are passed in the order of the stock solution and water, and the flow-out is A preceding step is performed in which the liquid is circulated through the packed bed for at least two cycles in the order of outflow, and after the circulation of the preceding step, an oligosaccharide liquid of trisaccharides or more, oligosaccharides of trisaccharides or more, and saccharides of disaccharides or less are extracted from the outlet. Of the effluent that flows out in the order of a mixed liquid and a sugar liquid of disaccharides or less, a relatively pure oligosaccharide liquid part of a specified amount of trisaccharides or more, and a relatively pure oligosaccharide liquid part of a specified amount of disaccharides or less. Only the sugar liquid portion is taken out of the system, while the other liquids are circulated again in the order of flow. At this time, a specified amount of the stock solution is added to the circulating liquid, a mixture of oligosaccharides of trisaccharides or higher and saccharides of disaccharides or lower. Inject it during the inflow, and also inject a specified amount of water after the inflow of sugars with relatively low concentrations of disaccharides or less, which are circulating fluid, and take out the total amount of the injected stock solution and water from the system. A steady process is carried out in which the liquid volume of the oligosaccharide containing trisaccharides or more and a sugar solution containing disaccharides or less is made equal to the total liquid volume, and by repeating this steady process thereafter, A method for separating oligosaccharides of trisaccharides or higher, characterized by sequentially taking out an oligosaccharide liquid and a saccharide liquid of lower than disaccharides. 2. The method for separating oligosaccharides according to claim 1, wherein an alkali metal hydroxide, an alkaline earth metal hydroxide, or an alkali salt of an alkali metal or an alkaline earth metal is added to the stock solution or water. 3. Claim 1, in which an aqueous solution of an alkali metal hydroxide, an alkaline earth metal hydroxide, or an alkali salt or a neutral salt of an alkali metal or an alkaline earth metal is periodically passed through a strongly acidic cation exchange resin. Method for separating oligosaccharides as described in section.