JP2891081B2 - Method for producing water-soluble polysaccharide - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a water-soluble polysaccharide, and more particularly, to an aqueous solution of a water-soluble polysaccharide, which is visually superior in quality and does not cause deterioration with time such as turbidity. The present invention relates to a method for efficiently and easily producing a polysaccharide.

[0002]

BACKGROUND OF THE INVENTION When extracting water-soluble polysaccharides from beans such as soybeans and peas containing a large amount of proteins, the present inventors have proposed a method for extracting proteins abundantly present in the beans into a water-soluble fraction so as not to elute them. It has been found that extraction of the protein contained in the solution at a pH near the isoelectric point facilitates the subsequent purification step.
No.).

[0003] However, the aqueous solution of the water-soluble polysaccharide prepared by this method was able to prevent clouding due to the protein which is decomposed and eluted as in the past, but is still insufficient for some applications. In today's world where quality improvement is increasingly required, further reduction in turbidity and improvement in transparency are required. The impaired transparency is due to insoluble suspended matter extracted as an impurity when extracting a water-soluble polysaccharide from beans. The water-soluble polysaccharide solution clouded by these suspended matters not only gives a visual discomfort, but when these water-soluble polysaccharides are blended in a beverage or the like, the suspended matter later precipitates and further gives a discomfort. In order to solve such a problem, a method is known in which a suspended matter is settled and removed using a centrifugal separator having a high centrifugal force, or a suspended matter is removed using a filter having a small pore size or a filter aid such as diatomaceous earth. ing. However, when high centrifugal force is used, it is a problem in production because the device is expensive. In addition, when various types of filtration are used, there is a problem that clogging is likely to occur due to the viscous suspended matter, so that too much processing cannot be performed.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to efficiently produce a water-soluble polysaccharide having a low turbidity of an aqueous solution from legumes by a simple method.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies in view of the above points, and found that when extracting water-soluble polysaccharides from beans, the aqueous solution of water-soluble polysaccharides extracted under acidic conditions was adjusted to a specific pH. It has been found that a water-soluble polysaccharide having a low aqueous turbidity, which was difficult with the conventional technique, can be produced by performing filtration or centrifugation after the heat treatment in the region. The present invention has been completed based on such findings.

That is, according to the present invention, a water-soluble polysaccharide aqueous solution extracted from beans under acidic conditions is adjusted to pH 6 or more and less than 9,
A process for producing a water-soluble polysaccharide, which comprises subjecting the precipitate to heat treatment and separating and removing a precipitate.

[0007] According to the present invention, most of the insoluble matter produced when a water-soluble polysaccharide is prepared by extracting it from a legume under an acidic condition contains insoluble proteins, insoluble salts, and some of the finely divided raw materials. And so on. Among these, sedimentation of proteins is hindered by the protein stabilizing ability of the water-soluble polysaccharide. For this reason, these proteins are difficult to precipitate even by isoelectric point precipitation or addition of cations. This is because an aqueous solution of a water-soluble polysaccharide, which is an anionic system, further enhances the protein stabilizing ability near the isoelectric point of the protein on the acidic side.

However, conversely, these anionic polysaccharides have reduced protein stabilizing ability at a pH near neutrality or at a pH in an alkaline range. In addition, the dispersibility is further reduced by heating. Utilizing this phenomenon, if centrifugation is performed after performing the above-mentioned treatment, insoluble proteins and the like floating at a low gravitational acceleration can be removed. Further, aggregates such as proteins generated by performing such a treatment are relatively hard, and filtration becomes easier than before the treatment.

Hereinafter, the method of the present invention will be described in detail. First, beans and beans, preferably soybeans, especially soybean cotyledons are used as a raw material, and heat extraction is performed under acidic conditions. The pH of the extract extracted from these beans is adjusted to 6 or more and less than 9. When the pH is lower than 6, the protein is solubilized and has no effect. In the case of a solution containing a large amount of polyuronic acid as a water-soluble polysaccharide, these polysaccharides precipitate. When the pH is high, the protein is solubilized as in the case of the low pH, and at the same time, the deterioration of the flavor and the deterioration of the color tone due to browning become severe.

Next, regarding the heat treatment conditions, 30 ° C. to 1 ° C.
20 ° C, preferably 40 ° C to 100 ° C, more preferably 50 ° C to 90 ° C is suitable. Heat treatment temperature is 30
When the temperature is lower than ℃, aggregation precipitation of proteins and the like is slow, and the treatment time is long. In addition, when the temperature is high, browning and flavor deterioration become severe. However, the deterioration of the color due to the deterioration of the flavor or browning caused by this heat treatment may be caused by one or more reducing agents selected from sodium hyposulfite, potassium hyposulfite, sodium bisulfite and potassium bisulfite, or hypochlorite. It is improved by adding an appropriate amount of one or two or more oxidizing agents selected from sodium oxyacid, calcium hypochlorite, hydroxy calcium hypochlorite and hydrogen peroxide. If these reducing agents or oxidizing agents are added in the above-mentioned polysaccharide extraction step, the generation of substances causing deterioration is prevented, and the effect of the remaining reducing agents or oxidizing agents is fully evaluated. It is also exhibited in the heating step of the invention, and these deteriorations are suppressed.

In the present invention, the effect is enhanced when the above pH adjustment is performed and the heat treatment is performed, and at the same time, a protease or other protease is acted on, or the heat treatment is performed after the enzyme treatment. Examples of proteolytic enzymes include pepsin, subtilisin, bromelain, papain, and the like. These proteolytic enzymes are appropriately used to reduce the size of insoluble proteins to solubilize them. In this case, the protein is not solubilized to 100%, and some hydrophobic amino acids and incompletely degradable proteins and peptides remain as insolubles. However, these insolubles are less viscous than the protein before decomposition, and are less likely to be stabilized by polysaccharides. Therefore, when used in combination with the above-described heat treatment, the effect of removing suspended matters is enhanced, and at the same time, the turbidity of the aqueous solution of the water-soluble polysaccharide is reduced. Further, even if the water-soluble polysaccharide solution containing insolubles obtained by using this method is filtered, the filtration surface is not clogged, and the filtration speed and the throughput are improved even with the same filtration area.

[0012] By the above-mentioned method, suspended matter containing protein as a main component can be removed, but it is difficult to decompose in the case of an insoluble salt, and in the case of a part of the finely divided raw material, Most of its components are insoluble polysaccharides. Therefore, it is possible to reduce the turbidity using enzymes such as cellulase, hemicellulase, or pectinase that decomposes them, but using the enzymes that decompose these polysaccharides, even the target water-soluble polysaccharides May be hydrolyzed, and the function of the polysaccharide may not be exhibited.

When removing the above impurities,
It becomes possible by adding various coagulants after the above-mentioned heat treatment. In this case, although the type of the coagulant to be used cannot be unconditionally defined depending on the object to be removed, an inorganic or organic polymer coagulant is used alone or in combination.
However, depending on the type of the raw material beans, when an inorganic cationic coagulant is used, the polysaccharide itself may coagulate and precipitate. In such a case, it is preferable to use a polymer anionic coagulant such as organic sodium polyacrylate, sodium alginate or xanthan gum, or a polymer cationic coagulant such as chitosan. However, in the case of a polymer-based flocculant, the amount of the polymer flocculant has an adverse effect depending on the amount of the polymer flocculant. These conditions may be determined after experimental confirmation.

[0014]

【Example】

Example 1 Preparation of Water-Soluble Soybean Polysaccharide A Raw okara obtained in the isolated soybean protein production process
Water was added, and the pH was adjusted to 5.0 with hydrochloric acid.
The mixture was heated and extracted at 2.5 ° C. for 2.5 hours. After cooling, the mixture was centrifuged (10000 G × 30 minutes) to separate the supernatant and the precipitate. A 0.1N aqueous solution of sodium hydroxide was added to the polysaccharide extract thus obtained to adjust the pH to 7. Then, it heated at 60 degreeC for 1 hour. Further, this aqueous solution is centrifuged (1000G × 30
Then, the supernatant was freeze-dried to obtain a water-soluble polysaccharide A.

COMPARATIVE EXAMPLE 1 Preparation of Water-Soluble Soybean Polysaccharide B In the same manner as in Example 1, twice the amount of water was added to raw okara obtained in the step of producing a separated soybean protein, and the pH was adjusted to 5.0 with hydrochloric acid.
And extracted by heating at 125 ° C. for 2.5 hours. After cooling, the product was centrifuged (10000 G × 30 minutes) to separate into a supernatant and a precipitate. The polysaccharide extract thus obtained was further centrifuged (1000 G × 30 minutes), and the supernatant was freeze-dried to obtain a water-soluble polysaccharide B.

A 3% aqueous solution of the water-soluble soybean polysaccharides A and B obtained as described above is prepared, and the spectrophotometer is used to measure the aqueous solution at 610 nm.
The turbidity of the aqueous solution was determined by measuring the absorbance at the wavelength. That is, the higher the value, the lower the transparency,
The lower the value, the higher the transparency.

○ Turbidity of each water-soluble polysaccharide −−−−−−−−−−−−−−− Sample Turbidity (OD610) −−−−−−−−−−−−−−−− Example 1 0.020 Comparative Example 1 0.204 --------------------------

From the above results, it can be seen that the turbidity is considerably reduced when the water-soluble soybean polysaccharide is purified by the method of the present invention.

Example 2 Preparation of water-soluble soybean polysaccharide C
Water was added, and the pH was adjusted to 5.0 with hydrochloric acid.
The mixture was heated and extracted at 2.5 ° C. for 2.5 hours. After cooling, the product was centrifuged (10000 G × 30 minutes) to separate into a supernatant and a precipitate. A 0.1N aqueous solution of sodium hydroxide was added to the polysaccharide extract thus obtained to adjust the pH to 7. Then, it heated at 60 degreeC for 1 hour. Further, this aqueous solution was applied to Toyo Filter Paper No. 5A
(150 mm) and filtered. This was dried to obtain a water-soluble polysaccharide C.

Comparative Example 2 Preparation of Water-Soluble Soybean Polysaccharide D As in Example 2, twice the amount of water was added to the raw okara obtained in the step of producing the separated soybean protein, and the pH was adjusted to 5.0 with hydrochloric acid.
And extracted with heat at 125 for 2.5 hours. After cooling, the product was centrifuged (10000 G × 30 minutes) to separate into a supernatant and a precipitate. The polysaccharide extract thus obtained is further subjected to Toyo Filter Paper N.
o. Filtered using 5A (150 mm). This was freeze-dried to obtain a water-soluble polysaccharide D.

The turbidity of the water-soluble polysaccharide thus obtained was compared with the throughput during filtration. The results are as follows. ○ Results --------------------------------------------------------- Sample turbidity Amount of treatment (Example: 100) -------------------- −−−−−−−−−−−−−−−−−−− Example 2 0.037 100 Comparative example 2 0.139 64 −−−−−−−−−−−−−−−−−−−−−−−− −−−

The above results show that the use of the method of the present invention not only provides a water-soluble polysaccharide having low aqueous solution turbidity, but also improves the throughput during filtration.

Example 3 Preparation of water-soluble soybean polysaccharide E
Water was added, and the pH was adjusted to 5.0 with hydrochloric acid.
The mixture was heated and extracted at 2.5 ° C. for 2.5 hours. After cooling, the product was centrifuged (10000 G × 30 minutes) to separate into a supernatant and a precipitate. A 0.1N aqueous solution of sodium hydroxide was added to the polysaccharide extract thus obtained to adjust the pH to 7. Then, it heated at 60 degreeC for 1 hour. To this solution, a 0.1% aqueous solution of sodium polyacrylate was added at 1% based on the solid content of the aqueous solution, and the mixture was stirred for 10 minutes. Furthermore, this aqueous solution is centrifuged (1000G × 30 minutes)
Then, the supernatant was freeze-dried to obtain a water-soluble polysaccharide E.

Comparative Example 3 Preparation of Water-Soluble Soybean Polysaccharide F Raw okara obtained in the isolated soybean protein production process
Water was added, and the pH was adjusted to 5.0 with hydrochloric acid.
The mixture was heated and extracted at 2.5 ° C. for 2.5 hours. After cooling, the product was centrifuged (10000 G × 30 minutes) to separate into a supernatant and a precipitate. To this solution, a 0.1% aqueous solution of sodium polyacrylate was added at 1% based on the solid content of the aqueous solution, and the mixture was stirred for 10 minutes. further,
This aqueous solution was centrifuged (1000 G × 30 minutes), and the supernatant was freeze-dried to obtain a water-soluble polysaccharide F.

○ Results ------------------- Sample turbidity (OD610) --------------------------- 0.011 Comparative Example 3 0.063 Comparative Example 1 0.204 (for reference) -----------------

From the above results, it can be seen that when the water-soluble soybean polysaccharide is purified by the method of the present invention, the turbidity is considerably reduced as compared with the case where only sodium polyacrylate is used. The effect of sodium polyacrylate is seen from the results of Comparative Example 1.

Example 4 Preparation of Water-Soluble Polysaccharide G Raw okara obtained in the step of producing isolated soybean protein was added with 2
Sodium hyposulfite was added at 0.5% per solid for the purpose of preventing color tone deterioration in the polysaccharide extraction step or the heating step after extraction, and the pH was adjusted to 5.0 with hydrochloric acid.
0, and extracted by heating at 125 ° C. for 2.5 hours. After cooling, the mixture was centrifuged (10000 G × 30 minutes) to separate the supernatant and the precipitate. To the polysaccharide extract thus obtained, a protease preparation (Nulase F: Amano Pharmaceutical Co., Ltd.) was added at 5% based on the solid content, and reacted at 45 ° C. for 60 minutes. Then p
The temperature was adjusted to H7 and heating was performed at 90 ° C. for 10 minutes to inactivate the enzyme, and at the same time, heat treatment was performed. After this process,
Toyo filter paper No. Filtered using 5A (150 mm). The dried product was dried to obtain a water-soluble polysaccharide G.

Comparative Example 4 Preparation of Water-Soluble Polysaccharide H As in Example 4, twice the amount of water was added to the raw okara obtained in the step of producing the separated soybean protein, and the pH was adjusted to 5.0 with hydrochloric acid.
And extracted by heating at 125 ° C. for 2.5 hours. After cooling, the product was centrifuged (10000 G × 30 minutes) to separate into a supernatant and a precipitate. To the polysaccharide extract thus obtained, a protease preparation (Neurase F: Amano Pharmaceutical Co., Ltd.) was added to a solid content of 5%.
%, And reacted at 45 ° C. for 60 minutes. Subsequent enzyme deactivation was performed at pH 5. After this treatment, Toyo Filter Paper No. 5
A (150 mm) and filtered. This was dried to obtain a water-soluble polysaccharide H.

The turbidity of the water-soluble polysaccharide thus obtained was compared with the treatment amount at the time of filtration. The results are as follows. ○ Results --------------------------------------------------------------------------- Turbidity Treatment amount (Example 4 was set to 100) --------------------------------------------------------------------------------------------- −−−−−−−−−−−−−−−−−−−−− Example 4 0.018 100 Comparative Example 4 0.072 87 Comparative Example 2 0.139 84 (for reference) −−−−−−−−−−− From the above results, the inactivation after the enzyme was actuated at pH 5 was lower than that at pH 5 when the enzyme was actuated. The degree was low, and the throughput per hour during filtration was high. In addition, the effect of the protease treatment is seen from the result of Comparative Example 2.

Example 5 Preparation of Water-Soluble Soybean Polysaccharide I The raw okara obtained in the isolated soybean protein production process was prepared by adding 2
Sodium hyposulfite was added at 0.5% per solid for the purpose of preventing color tone deterioration in the polysaccharide extraction step or the heating step after extraction, and the pH was adjusted to 5.0 with hydrochloric acid.
After adjusting to 0, the mixture was heated and extracted at 125 ° C. for 2.5 hours.
After cooling, the mixture was centrifuged (10000 G × 30 minutes) to separate the supernatant and the precipitate. A 0.1N aqueous solution of sodium hydroxide was added to the polysaccharide extract thus obtained to adjust the pH to 7. Then, it heated at 60 degreeC for 1 hour. Further, this aqueous solution was centrifuged (1000 G × 30 minutes), and the supernatant was freeze-dried to obtain a water-soluble polysaccharide I.

The water-soluble polysaccharides (A) to (I) separated in each of the above examples were subjected to a sensory evaluation by 10 panelists. As a result, (I) and (G) were the most white and had good color tone.
All answered that the flavor was good.

[0032]

As described above, after the aqueous solution of the water-soluble polysaccharide extracted from beans under acidic conditions is adjusted to pH 6 or more and less than 9,
By performing heat treatment and separating and removing the precipitate, the turbidity of the water-soluble polysaccharide aqueous solution, which has been difficult with the conventional technology, can be reduced. Further, by adding a reducing agent or an oxidizing agent during the treatment process, or by adding a protease treatment or a polymer flocculant, the effect of further improving the flavor and color tone was obtained.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C08B 37/00 A61K 35/78 C08B 37/14

Claims (9)

(57) [Claims] 1. A process for producing a water-soluble polysaccharide, comprising preparing an aqueous solution of a water-soluble polysaccharide extracted from beans under an acidic condition to have a pH of 6 or more and less than 9, followed by heat treatment to separate and remove a precipitate. . 2. The method according to claim 1, wherein the beans are soybeans. 3. The method according to claim 1, wherein the soybean is a cotyledon portion of a seed. 4. The method according to claim 1, wherein the heat treatment is performed by adding a reducing agent or an oxidizing agent. 5. The method according to claim 1, wherein the reducing agent is one or more selected from sodium hyposulfite, potassium hyposulfite, sodium bisulfite and potassium bisulfite.
The method according to any one of the above. 6. The method according to claim 1, wherein the oxidizing agent is one or two or more selected from sodium hypochlorite, calcium hypochlorite, hydroxycalcium hypochlorite and hydrogen peroxide. The method described in Crab. 7. The method according to claim 1, wherein the protease treatment is performed during or before the heat treatment. 8. The method according to claim 7, wherein the protease is any one of pepsin, subtilisin, bromelain and papain. 9. The method according to claim 1, wherein a polymer flocculant is added during separation and removal.