JPH07196678A - Method for isomerizing compound having aldose structure to compound having ketose structure and isomerization agent or its promotion agent - Google Patents

Abstract

PURPOSE:To obtain an isomerized glucose syrup, etc., by safely and efficiently isomerizing a compound having aldose structure with a specific organic germanium compound into a compound having ketose structure without necessitating particular apparatuses and complicate operations. CONSTITUTION:A compound having aldose structure such as monosaccharide, disaccharide and oligosaccharide is isomerized to a compound having ketose structure by an organic germanium compound expressed by formula I or formula II (R1 and R2 each is H or a lower alkyl; X is OH, a lower alkyl or an O-lower alkyl; n is >=3).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for isomerizing a compound having an aldose structure into a compound having a ketose structure, and an isomerizing agent or an isomerization accelerator used in this isomerization.

[0002]

2. Description of the Related Art It is known that monosaccharides are the main constituents of carbohydrates, which are extremely important for living things as energy sources and are the most abundant organic compounds on the earth, These monosaccharides typically have a structure in which carbon atoms having 3 to 8 carbon atoms are connected in a ring, and are structurally roughly classified into two types.

That is, it can be classified into aldose, which is a sugar of aldehyde, and ketose, which is a sugar of ketone. Each of aldose and ketose is
It is classified as triose, tetrose, pentose and hexose according to the number of carbon atoms. And, regarding the reaction of the above monosaccharide, various things are known, but as an industrially carried out reaction, glucose which is an aldohexose (glucose) is converted to fructose (fructose) which is a corresponding ketohexose. Isomerized,
A reaction for producing an isomerized sugar can be mentioned.

The above-mentioned isomerized sugar is a mixture of fructose obtained by isomerizing a part of glucose and glucose as a raw material. Glucose having a low sweetness is partially converted into fructose having a strong sweetness, and sugar ( It has a sweetness similar to that of sucrose.

The fructose, which is a component of the above-mentioned isomerized sugar, has a stronger sweetness as the temperature is lower, so about 70% of the total consumption thereof is added to beverages such as soft drinks, and other than that, it is used in general food products. The annual production is about 8 million tons worldwide.

[0006] Both glucose and fructose are hexoses having similar structures, and isomerization by various methods has been proposed for a long time, but nowadays, a part of glucose is produced by using an isomerase (glucose isomerase). It is industrially carried out to produce an isomerized sugar by isomerizing sucrose into fructose.

[0007] That is, a liquor obtained by liquefying starch such as corn starch and saccharifying with glucoamylase is immobilized by isomerizing enzymes produced by bacteria belonging to bacterial species such as Streptomyces by various methods. Glucose is isomerized into fructose by continuous passage through the enzyme.

The above-mentioned isomerization is an equilibrium reaction in which the equilibrium point is around 1, and when the equilibrium is reached, about 60
It is possible to isomerize about 50% of glucose to fructose at a reaction temperature of ℃, but it takes a considerably long time to proceed the isomerization to this extent, and the reaction solution is heated due to this long heating. Purification for commercialization,
Since the cost in the concentration step increases, the reaction is terminated when the isomerization progresses to a fructose content of about 42%.

As described above, isomerized sugar is produced for the purpose of imparting a sweetness similar to sugar to glucose, which can be produced in large quantities at low cost, and the sweetness of sugar was set to 100. In this case, since the sweetness of the isomerized sugar containing about 42% of fructose described above (hereinafter also referred to as 42% isomerized sugar) is 95 to 100, which is slightly insufficient, only the above isomerization reaction is performed. Then, it is impossible to directly obtain the isomerized sugar having the sweetness of sugar.

Therefore, at present, the content of fructose in 42% isomerized sugar is increased to 55% and the sweetness is 100 to 1
55% isomerized sugar as 10 is industrially produced.

[0011]

However, the above-mentioned 4
In order to convert 2% isomerized sugar into 55% isomerized sugar, not only a large-scale facility such as a reaction tower packed with a cation exchange resin is required, but also continuous sugar separation using the reaction tower is performed. First, a fructose liquid having a fructose content of about 95% was obtained.
There is a problem that the operation is complicated, such as mixing% isomerized sugar.

On the other hand, examples of the isomerization of another compound having an aldose structure to a compound having a ketose structure include isomerization of lactose belonging to the disaccharide to lactulose. Differently, an enzyme that isomerizes lactose to lactulose has not been discovered so far, so a method of adding sodium hydroxide so that the concentration is lower than a predetermined concentration with respect to lactose and heating the mixed solution to a temperature of 70 ° C or higher ( Japanese Patent Sho 52
Isomerization to lactulose is carried out according to JP-A-2984). However, in this method, the isomerization rate,
That is, the production rate of lactulose is 20% or less, which is lower than the production rate of fructose, and there is a problem that the lactulose solution obtained must be concentrated in order to obtain a syrup containing lactulose at a high concentration.

The present invention solves the above-mentioned drawbacks of the prior art, and isomerizes a compound having an aldose structure into a compound having a ketose structure at a high isomerization rate without requiring special equipment or complicated operation. It was made for the purpose of providing a method that can be carried out, and an isomerization or an accelerator thereof used at that time.

[0014]

[Means for Solving the Problems] In order to achieve the above object, the composition of the method for isomerizing a compound having an aldose structure adopted in the present invention into a compound having a ketose structure is as follows:
Formula (1)

[Chemical 7] Or formula (2)

[Chemical 8] (In the formula, R ₁ and R ₂ are hydrogen atoms or the same or different lower alkyl groups, and X is a hydroxyl group, a lower alkyl group or O-
A lower alkyl group, and n represents an integer of 3 or more)
The present invention is characterized by isomerizing a compound having an aldose structure into a compound having a ketose structure with or in the presence of an organic germanium compound represented by: The composition of the glucose isomerization agent adopted by (1) is characterized by using the above-mentioned organic germanium compound as a main component.

The present invention will be described in detail below.

In the present invention, the isomerization of the compound having the aldose structure into the compound having the ketose structure as described above is carried out by the organogermanium compound represented by the above formula or in the presence thereof. First, such an organic germanium compound will be described.

That is, the above-mentioned organic germanium compound is already known (for example, Japanese Patent Publication No. 57-538).
No. 00, Japanese Patent Publication No. 59-36997, Japanese Patent Publication No. 5
9-36998, etc.), for example, Japanese Patent Publication No. 59-1
It can be produced by the method described in Japanese Patent No. 8399.

Specifically, a halogermanium phosphate complex obtained by treating germanium dioxide with hypophosphorous acid or a salt thereof in hydrohalic acid is represented by the formula:

[Chemical 9] The compound represented by the formula

[Chemical 10] (Wherein X is a halogen atom), an organic germanium compound is obtained by dissolving the compound in acetone or another organic solvent mixed with water, and adding water to the solution. To get.

R ₁ and R ₂ in the above formulas (1) and (2) are hydrogen atoms or the same or different lower alkyl groups such as methyl group, ethyl group and propyl group, X is a hydroxyl group,
A lower alkyl group or an O-lower alkyl group similar to R ₁ and R ₂ is shown, and n is an integer of 3 or more. Therefore, the organic germanium compound used in the present invention is shown in Table 1 below. Such compounds (3) to (5) can be exemplified.

[Table 1]

The organogermanium compounds represented by the above-mentioned organogermanium compounds used in the present invention are subjected to instrumental analysis such as nuclear magnetic resonance (NMR) spectrum and infrared absorption (IR) spectrum, and the results are shown in the above-mentioned document. By comparing with the values shown, it was confirmed that these compounds are represented by the above general formula.
Regarding the organogermanium compound, it is considered that the above formula (1) more accurately represents the structure.

As described above, the present invention provides a compound having an aldose structure, a compound having a ketose structure, with or without the presence of the organic germanium compound represented by the above formula (1) or (2). The compound that undergoes isomerization to
aldose structure shown by er projection

[Chemical 11] In the compound, the reaction formula

[Chemical 12] , The ketose structure shown by the Fischer projection method via the cis-enediol structure intermediately.

[Chemical 13] Any compound that can be isomerized into a compound having

First, as the compound having the aldose structure, a monosaccharide or a derivative thereof can be mentioned.
The compounds listed on the left below are isomerized to the compounds listed on the right. Glyceraldehyde → dihydroxyacetone erythrose, threose → erythrulose ribose, arabinose → ribulose xylose, lyxose → xylulose allose, altrose → psicose glucose, mannose → fructose glucose, idose → sorbose galactose, talose → tagatose

As the compound having the aldose structure, a reducing disaccharide or a derivative thereof can be mentioned.
Similar to the above, the compounds listed on the left below are isomerized to the compounds listed on the right. Maltose → Maltulose Lactose → Lactulose

Further, oligosaccharides or polysaccharides of trisaccharides or more having the above aldose structure or polysaccharides or derivatives thereof can be isomerized, but in that case, those having an aldose structure at the end are targeted. In the above compounds, for maltose and lactose, for example, an enzyme that isomerizes to a compound having a corresponding ketose structure has not been found until now.

Among the compounds having the above ketose structure, lactulose is clinically administered to improve neuropsychiatric disorders associated with hyperammonemia and tremor of fingers and the like.

In order to isomerize the compound having the aldose structure, an isomerase may not be used, or an isomerase may be used in combination. Is similar to the conventional method of isomerizing glucose to fructose using an isomerase, for example, in the state where an alkali such as sodium hydroxide or calcium hydroxide is added, at room temperature to 60 to 90 ° C.
It may be carried out at the above temperature, and it is also preferable to use the alkaline side of the electrolyzed water obtained by polarizing the water in the weak electrolyzed water producing apparatus.

The concentration at the time of isomerization is determined by the time for isomerization, the desired isomerization rate, etc., and is not particularly limited, but for example, it has an aldose structure. The organic germanium compound may be used in an amount of about 1% by weight or more in a 10% by weight to saturated solution of the compound.

In the isomerization according to the method of the present invention, the isomerization rate generally rises according to the reaction time. Therefore, the isomerization rate is controlled by adjusting the reaction time until the desired isomerization rate is reached. Can be converted.

In the isomerization method of the present invention, an isomerization enzyme can be used in combination as in the conventional isomerization of glucose to fructose by an isomerization enzyme.

That is, the isomerization of glucose to fructose will be described as an example. First, starch such as corn starch is liquefied with α-amylase of Bacillus genus and the like, and then Aspergillus niger (Aspergillus niger) is liquefied.
It is saccharified with glucoamylase of gillus niger) to obtain a sugar solution. The glucose content of this sugar solution was about 9
It is in the range of 3 to 95%. During saccharification, pullulanase, which is an enzyme that cleaves the α-1,6-glucoside bond of starch, may be used in combination, and in such a case, the glucose content in the sugar solution is about 96%. .

If necessary, the sugar solution is purified and concentrated, and if necessary, metal ions of magnesium, manganese or cobalt required by the isomerase are added. From the viewpoint of food hygiene, magnesium ion is preferable as the metal ion.

Next, the above sugar solution is subjected to an isomerization step. The isomerase used at this time may be any one capable of isomerizing glucose into fructose, for example, strept. Myces (Streptomy
ces, Bacillus, Arthrobacter (Art
This is due to isomerase-producing bacteria such as the genus hrobacter and the genus Microbacterium. Specifically, Lactobacillus brevis Bacillus coagulans Brevibacterium pentosoaminoacidicum Arthrobactor sp. Actinoplanes missouriensis Streptomyces pheochromogenes Streptomyces rubiginosus Streptomyces albus NRRL-5778 Streptomyces griseofuscus and the like can be exemplified.

Then, with the organic germanium compound exemplified by the above compound or in the presence thereof, the isomerase is allowed to act on the sugar solution to isomerize glucose in the sugar solution to fructose. This step may be performed in a solution in which the sugar solution is mixed with an organic germanium compound and an isomerase, but following the conventional method, using an immobilized enzyme in which the isomerase is immobilized by various methods, A sugar solution containing an organic germanium compound may be continuously passed through this immobilized enzyme. In addition, in the present invention, it is possible to use the bacterial cells in which the bacterial protein other than the isomerase is inactivated as they are.

The conditions for the isomerization of glucose to fructose according to the present invention are the same as in the conventionally known method, for example, neutral to weakly alkaline, 60 to 90 ° C.
It should be done at the temperature of.

Furthermore, in the isomerization of glucose to fructose according to the present invention, as is clear from the examples described below, the isomerization rate increases with the passage of reaction time,
The isomerization rate can be controlled by adjusting the reaction time, and the isomerization can be performed until the desired isomerization rate, for example, the isomerization rate to fructose reaches about 55% or more.

The amount of the organic germanium compound used in the present invention may be determined according to the desired isomerization ratio and the like, and for example, a concentration range of 1/100 M or more can be mentioned.

[0037]

EXAMPLES The present invention will now be described in more detail with reference to Examples.

Example 1 (1) Synthesis of Organic Germanium Compound According to the method described in JP-B-59-18399, organic germanium compounds (3) to (5) were synthesized.

(2) Preparation of Substrate Solution 40% glucose-1.2M organogermanium compound solution was prepared by the following procedure. 0.8 g of anhydrous glucose was added to 0.8 ml of deionized water and dissolved, and the organic germanium compounds (3) to (5) were added to the solution to adjust the pH of the solution to 1.2 M in terms of the number of moles of germanium. Was added little by little while keeping it on the slightly alkaline side and completely dissolved. Next, 4.9 mg of magnesium sulfate was added to adjust the pH of the solution to 8.0, and the total amount was adjusted to 2.0 ml with deionized water.

(3) Preparation of enzyme Streptomyces griseofus
The isomerase (glucose isomerase) extracted from the cells of cus S-41 was purified according to a known method using an ion exchange column, a gel filtration column, etc. until it became a single band electrophoretically, Used as.

(4) Enzyme isomerization reaction 0.7 ml of the above substrate solution, 0.1 ml of 200 mM MOPS buffer (pH 8.0), enzyme solution (5.69 mg / m 2)
l) 0.2 ml is put in a small test tube and reacted in a constant temperature bath at 60 ° C., and 50 μl of the reaction solution is preliminarily set to 50
The reaction was stopped by adding it to a microvial containing 0.5 μl of 0.5N perchloric acid. The amount of fructose produced in the stop solution was measured by high performance liquid chromatography (Shimadzu LC7A, SC
R-101 (N) column) was quantified, and the change with time of the isomerization rate between glucose and fructose was examined.

(5) Results The isomerization rate at equilibrium was 91.3% when the organogermanium compound (3) was used, 96.6% when the organogermanium compound (4) was used, and 5 (5). When used, it was 93.8%. The compounds other than the compounds shown in Table 2 showed almost the same isomerization rate. On the other hand, in the blank using only the enzyme, the isomerization rate was 42.0%.

Example 2 (1) Preparation of Weakly Electrolyzed Water Among the electrolyzed water obtained by passing water through a weakly electrolyzed water production apparatus (for example, "Microcluster" [trade name] manufactured by Asahi Glass Co., Ltd.), the alkaline side is taken out , Weakly electrolyzed water was prepared.

(2) Preparation of glucose solution 14 g of anhydrous glucose was added to the above-prepared weak electrolyzed water of about 80
After dissolving in 100 ml, add weak electrolyzed water to 100 ml.
And The pH immediately after the preparation was 9.01.

(3) Preparation of Organic Germanium Compound Solution Organic germanium compounds (3) to (5) were added to about 2 ml of deionized water so that the final concentration was 1.67 M, and a small amount of sodium hydroxide was added. Weakly alkaline (pH =
After adjusting to 8.00 and 8.53), deionized water was further added to make 3 ml.

(4) Isomerization 200 μl of glucose solution and 2 parts of organic germanium compound
After taking 00 μl and 200 μl of glucose solution and 200 μl of the weak electrolyzed water in a small test tube and mixing them well,
The reaction was carried out by keeping in a constant temperature water bath at ℃. After 1-3 hours,
After 50 μl of the reaction solution was added to 50 μl of 0.5N-HClO4 to stop the reaction, the reaction mixture was diluted 100 times with deionized water, and the amount of produced fructose and the amount of residual glucose were quantified by high performance liquid chromatography (Shimadzu 7A). did. or,
A system using no organic germanium compound was used as a blank.

(5) Isomerization of other saccharides Other saccharides were also isomerized in the same manner as above.

(6) The results are shown in Table 2 below. Table 2
Compounds other than the compounds shown in 1 showed almost the same isomerization rate.

[Table 2]

[0049]

As is apparent from the above examples, the present invention solves the drawbacks of the prior art, can isomerize a compound having an aldose structure into a compound having a ketose structure, and has a special No equipment or complicated operation is required.

Further, in the present invention, a compound having an aldose structure can be isomerized to a compound having a ketose structure without using an isomerizing enzyme or in combination with an isomerizing enzyme. It is possible to isomerize a compound having a ketose structure even if the compound has an aldose structure in which no isomerase that can be used is present, regardless of the condition of heating under alkaline conditions, which is disadvantageous in terms of isomerization rate. it can.

Further, the isomerization or its accelerator of the present invention which is useful when carrying out the above-mentioned method is extremely safe and excellent in stability.

Claims (17)

[Claims] 1. Formula (1): Or formula (2) (In the formula, R ₁ and R ₂ are hydrogen atoms or the same or different lower alkyl groups, and X is a hydroxyl group, a lower alkyl group or O-
A lower alkyl group, and n represents an integer of 3 or more)
A method comprising isomerizing a compound having an aldose structure into a compound having a ketose structure with an organic germanium compound represented by: 2. Formula (1): Or formula (2) (In the formula, R ₁ and R ₂ are hydrogen atoms or the same or different lower alkyl groups, and X is a hydroxyl group, a lower alkyl group or O-
A lower alkyl group, and n represents an integer of 3 or more)
A method comprising isomerizing a compound having an aldose structure into a compound having a ketose structure in the presence of an organic germanium compound represented by: 3. The method according to claim 1, wherein the organic germanium compound is represented by the above formula (1). 4. The organic germanium compound has the formula (1) or (2), wherein R ₁ and R ₂ are hydrogen atoms, X
The method according to claim 1 or 2, wherein is a hydroxyl group. 5. The method according to claim 1 or 2, wherein the organic germanium compound in the above formula (1) or formula (2) is _one in which R ₁ is a hydrogen atom, R ₂ is a methyl group, and X is a hydroxyl group. 6. The method according to claim 1, wherein the organic germanium compound is a compound of the formula (1) or (2), wherein R ₁ is a methyl group, R ₂ is a hydrogen atom, and X is a hydroxyl group. 7. The isomerization of a compound having an aldose structure into a compound having a ketose structure is carried out without the presence of an enzyme which isomerizes the compound having an aldose structure into a compound having a ketose structure. The method described. 8. The method according to claim 1 or 2, wherein when an enzyme that isomerizes a compound having an aldose structure into a compound having a ketose structure is present, the enzyme is used in combination. 9. The method according to claim 1, wherein the compound having an aldose structure is one that isomerizes to a compound having a ketose structure via an intermediate cis-enediol structure. 10. The method according to claim 1, wherein the compound having an aldose structure is a monosaccharide. 11. The method according to claim 1, wherein the compound having an aldose structure is a disaccharide. 12. The method according to claim 1, wherein the compound having an aldose structure is an oligosaccharide or a polysaccharide. 13. Formula (1): Or formula (2) (In the formula, R ₁ and R ₂ are hydrogen atoms or the same or different lower alkyl groups, and X is a hydroxyl group, a lower alkyl group or O-
A lower alkyl group, and n represents an integer of 3 or more)
An isomerization of a compound having an aldose structure to a compound having a ketose structure, or an accelerator thereof, which comprises an represented organic germanium compound as a main agent. 14. The isomerization or accelerator thereof according to claim 13, wherein the organic germanium compound is represented by the above formula (1). 15. The organic germanium compound according to the formula (1) or (2), wherein R ₁ and R ₂ are hydrogen atoms, X
The isomerization or accelerator thereof according to claim 13, wherein is a hydroxyl group. 16. The isomerization according to claim 13, wherein the organic germanium compound is one of the above formula (1) or formula (2), wherein R ₁ is a hydrogen atom, R ₂ is a methyl group, and X is a hydroxyl group. Accelerator. 17. The isomerization or its isomerization according to claim 13, wherein the organic germanium compound has the formula (1) or (2) wherein R ₁ is a methyl group, R ₂ is a hydrogen atom and X is a hydroxyl group. Accelerator.