JPH1036404A - Manufacture of polysaccharide containing uronic acid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polysaccharide rich in uronic acid from soybean hull, effectively. SOLUTION: A polysaccharide contg. not less than 20% uronic acid is obtd. by coexisting a soybean hull with an aq. soln. contg. e.g. hydrochloric acid and citric acid, pref. having a pH of 3-6, and after heat treating at 70-130 deg.C, pref. under a pressure of not more than 10kg/cm<2> by drying the soln. after removing insol. matters or by precipitating with the addn. of a polar org. solvent to the soln.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for efficiently producing a uronic acid-containing polysaccharide contained in soybean seed coat.

[0002]

2. Description of the Related Art Studies on polysaccharides contained in soybean seed coat have been conducted for a long time. For example, J. Chem. Soc.
(C), 1945-1949, 1966, using aqueous solutions of various chemicals, pectic acid, xylan,
Mannan-type polysaccharide has been successfully extracted. The chemical structure of some polysaccharides has been analyzed. In addition, Journal of the Japan Food Industry Association, Vol. 12, No. 9, No. 380
386 pages, 1965, the soybean husk was divided into several extraction categories by common extraction and separation methods such as hot water extraction or alkali extraction, and the saccharides contained in each category were qualitatively evaluated. Estimated. According to these documents, it is described that a polysaccharide containing uronic acid, which is an acidic saccharide, can be obtained as a polysaccharide extracted from soybean seed coat.

[0003] Uronic acid is present as a repeating unit constituting an acidic mucopolysaccharide. For example, xanthan gum, which is a kind of fermented polysaccharide, contributes to the development of its salt-tolerant function, and pectin has its gel-resistant property. It is an essential component for chemical action. As described above, uronic acid contributes to the expression of various important functions in polysaccharides. Therefore, it would be significant if uronic acid-rich polysaccharides among polysaccharides extracted from soybean hulls could be efficiently obtained.

[0004]

However, in the above literature, various polysaccharides are extracted and separated, but there is no technical idea of extracting a polysaccharide rich in uronic acid, and the function of such polysaccharides is not considered. Is not described at all. Furthermore, at the time of the polysaccharide extraction treatment, various chemicals are used and multi-stage extraction operations are performed. Therefore, these polysaccharide extraction methods cannot be said to be methods that can be employed on an industrial level.

Accordingly, an object of the present invention is to develop a method for efficiently producing a polysaccharide rich in uronic acid from soybean seed coat as a raw material.

[0006]

Means for Solving the Problems In view of the above-mentioned circumstances, the present inventors have made intensive studies and as a result, have found that a mixture obtained by dispersing soybean seed coat in water is subjected to heat treatment under acidic conditions to obtain the desired product. They have found that saccharides can be easily extracted, and have completed the present invention.

That is, according to the present invention, after soybean hulls are heat-treated at 70 to 130 ° C. in the presence of an acidic aqueous solution, the aqueous solution from which insolubles have been removed is dried, or a polar organic solvent is added to the aqueous solution. There is provided a method for producing a uronic acid-rich polysaccharide, which comprises causing a precipitate to form.

[0008] The soybean hull used as a raw material in the present invention may be one obtained by moulting ordinary soybean seeds as they are or by moistening them. It is convenient.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION As a soybean seed coat used in the present invention, a soybean peeled from a soybean seed can be used as it is, but for the purpose of the present invention, a pulverized material (about 1 to 5 mm) and a finely pulverized material (100 mm) are used.
To about 500 μm) or an ultra finely pulverized product (about 100 μm or less).

In the present invention, first, soybean seed coat is heat-treated in the presence of an acidic aqueous solution.
Preferably, it is set to 6. If the pH is lower than 3, the hydrolysis reaction proceeds too much, and the molecular weight of the polysaccharide is promoted, and the function of the obtained polysaccharide tends to be reduced. Conversely, above pH 6, polysaccharides are obtained, but not uronic acid-rich. In addition, polysaccharides can be extracted and separated under alkaline conditions, but in this case, the decomposition of lignin and the like contained in soybean hulls also proceeds at the same time, so that the extract becomes blackish brown, and a large amount is used for decolorization and purification. For example, it is not preferable that activated carbon is required.

As the acidic substance used for pH adjustment, any substance can be used, for example, hydrochloric acid, phosphoric acid, citric acid,
Any of tartaric acid, malic acid, acetic acid and the like may be used, or two or more of these may be used in combination. However, in the present invention, it is particularly preferable to adjust the pH only with hydrochloric acid, or to adjust the pH using a combination of hydrochloric acid and citric acid. In the latter case, a further improvement in the yield of the polysaccharide is also observed.

The acidic aqueous solution is used in an amount of 4 to
Used 10 times (weight). Outside this range, the workability is reduced, or only the treatment liquid having a low concentration of the target substance is obtained, and neither is efficient.

It is important that the heating is performed at a temperature of 70 to 130 ° C. When the temperature is lower than 70 ° C., the uronic acid content in the obtained polysaccharide is low, and the yield of the polysaccharide itself is poor. On the other hand, if the temperature is higher than 130 ° C., the amount of the brown substance generated due to the reaction between the protein and the saccharide contained in the soybean seed coat increases, which is not preferable. In the present invention, in particular, 100 ° C to 120 ° C.
C. is preferred in terms of polysaccharide yield, uronic acid content and color.

The heat treatment is carried out for 30 minutes to 5 hours, more preferably 30 minutes to 2 hours, with standing or stirring.
In the present invention, the heat treatment is carried out under pressure, more preferably 1 hour.
When performed under a pressure of 0 kg / cm ² or less, more desirable ones can be obtained in terms of the yield of polysaccharide, the content of uronic acid and the color tone, and the heat treatment time can be shortened. In addition, 10kg / cm
Even if the pressure is increased beyond ² , no corresponding increase in the effect is observed.

After the above-mentioned heat treatment, the mixture of soybean seed coat and the acidic aqueous solution is subjected to a wire mesh, a sieve, filter paper, a glass filter,
Treatment is performed using a ceramic filter, centrifugation or other appropriate means to separate and remove soybean seed coat residues. The target polysaccharide is dissolved in the thus obtained clear and transparent aqueous solution.

Next, the aqueous solution is neutralized by keeping it in an acidic state or by adding an alkaline substance such as sodium hydroxide, potassium hydroxide or sodium carbonate, and then, if necessary, using a decolorizing agent such as activated carbon or activated clay. To decolorize and purify,
Dry or dry a polar organic solvent such as methanol, ethanol, isopropanol, n-propanol, butanol, acetone, methyl ethyl ketone, diethyl ether and methyl ethyl ether, preferably the lower alcohol such as ethanol, with respect to the liquid part by 1 to 5 parts. After adding twice (by volume) and stirring appropriately, a precipitate is formed, and the precipitate is separated by filtration to obtain the uronic acid-rich polysaccharide desired in the present invention. The method of recovering a precipitate by using the polar organic solvent is superior to the method of drying and recovering the precipitate in terms of the yield of uronic acid.

The polysaccharide derived from soybean seed coat obtained as described above contains a large amount of uronic acid as a sugar composition, and more preferably 20% by weight based on the extracted polysaccharide (hereinafter the same unless otherwise specified). % Or more, more preferably 20 to 50% by weight, and hexose as the main sugar constituting the polysaccharide, more preferably 50% by weight or more based on the extract (the same unless otherwise specified). Things.

[0018]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples.

EXAMPLE 1 A soybean seed coat (Nisshin Oil Co., Ltd.) was placed in a 3-liter Erlenmeyer flask.
Product name: Nisshin Binfure, size: 5-10mm) 10
0 g and 1 liter of ion-exchanged water were added and dispersed.
Next, 1N-hydrochloric acid was added thereto to adjust the pH to 3, and then
It was placed in a pressure cooker (manufactured by Yamato Scientific Co., Ltd., model: SP52, the same applies hereinafter) and heat-treated at 121 ° C. under a pressure of 5 kg / cm ² for 1 hour. The treated material was cooled to 70 ° C., and the wire mesh (32
After coarsely separating kyoto miscellaneous substances such as soybean seed coat residue using a mesh), insoluble components are further filtered off using a glass filter (manufactured by Toyo Roshi Kaisha, Ltd., model: GA-200, the same applies hereinafter), and the mixture is transparent. 600 ml of a fresh filtrate were obtained. Then 3
A double volume of ethanol was added, the mixture was gently stirred, and the resulting white precipitate was separated by filtration with filter paper and dried to obtain 8.5 g of a polysaccharide derived from soybean seed coat, which was the object of the present invention.

Comparative Example 1 In the same manner as in Example 1, 100 g of soybean seed coat was dispersed in 1 liter of ion-exchanged water. This dispersion had a pH of 6.4.
The dispersion was heated for 1 hour at 70 ° C. under normal pressure without adjusting the pH of the dispersion. Then, the treated product was treated in the same manner and under the same conditions as in Example 1 to obtain 2.3 g of polysaccharide.

Comparative Example 2 In the same manner as in Example 1, 100 g of soybean seed coat was dispersed in 1 liter of ion-exchanged water. Then, the mixture was adjusted to pH 3 by adding 1N-hydrochloric acid, and then heat-treated at 60 ° C. under normal pressure for 1 hour. Then, the treated product was treated in the same manner and under the same conditions as in Example 1 to obtain 3.6 g of a polysaccharide.

The polysaccharides derived from soybean hulls obtained in Example 1 and Comparative Examples 1 and 2 were subjected to sugar analysis. Uronic acid content is Bl
umenkrantz method (Analytical Biochemistry, 54th edition)
Pp. 484-486, 1973), and the hexose content was determined by the phenol-sulfuric acid method (for example, Sakuzo Fukui, "Quantitative Method for Reducing Sugar, 2nd Edition", 50th Edition).
, Page 52, 1990, described in Gakkai Shuppan Center Co., Ltd.) (the same applies hereinafter). The results are shown in Table 1. From comparison between the examples and comparative examples, it was revealed that the method of the present invention can effectively extract polysaccharides rich in uronic acid.

[0023]

[Table 1] * 1: Based on the weight of the extracted polysaccharide. * 2: Based on the weight of the extract.

Example 2 100 g of soybean seed coat (same as in Example 1) was added to deionized water 1
Dispersed in liters. Then, 30% acetic acid was added to adjust the pH to 5.
Then, the mixture was heated in a pressure cooker at 121 ° C. under a pressure of 1 kg / cm ² for 1 hour. The treated product was cooled to 70 ° C., and the insolubles such as soybean seed coat residue were roughly separated using a centrifugal separator. The insolubles were further filtered off using a glass filter to obtain 600 ml of a transparent filtrate. . Next, this is 5
A double volume of ethanol was added, and the resulting white precipitate was separated by filtration with filter paper and air-dried to obtain 6.5 g of the polysaccharide of the present invention. As a result of sugar analysis of the polysaccharide, uronic acid content: 39.1% by weight,
Hexose content: 63.8% by weight.

Example 3 100 g of soybean seed coat (same as in Example 1) was added to deionized water 1
Dispersed in liters. After adding and dissolving 7.5 g of citric anhydride thereto, the pH was measured to be 3.5. This dispersion was heated at 80 ° C. under normal pressure for 2 hours. The treated product was cooled to 70 ° C. and treated in the same manner and under the same conditions as in Example 1 to obtain 4.3 g of the polysaccharide of the present invention. As a result of sugar analysis of the polysaccharide, uronic acid content: 22.9
Hexose content: 75.0% by weight.

Example 4 100 g of soybean seed coat (same as in Example 1) was added to deionized water 1
Dispersed in liters. After adding and dissolving 7.5 g of citric anhydride thereto, the pH was adjusted to 3 by further adding 1N-hydrochloric acid. This dispersion is placed in a pressure cooker at 121 ° C., 1 kg / cm
Heat treatment was performed under pressure of ² for 1 hour. The treated product was cooled to 70 ° C., and the insolubles were removed in the same manner as in Example 1 to obtain 600 ml of a transparent filtrate. 3.3 g of powdered activated carbon was added to the filtrate and stirred for 1 hour. After filtration, a three-fold volume of ethanol was further added, and the resulting white precipitate was separated by filtration and dried under reduced pressure to obtain 5.8 g of the polysaccharide of the present invention. As a result of analyzing the sugar content of the polysaccharide, the uronic acid content was 44.0% by weight and the hexose content was 61.4% by weight. The polysaccharide obtained in this example was superior to those of Examples 1 to 3 in terms of whiteness.

Example 5 1 kg of soybean seed coat (finely pulverized material used in Example 1, size: 100 to 500 μm) was added to 5 liters of ion-exchanged water and dispersed. After adjusting the pH to 4 by adding 1N-hydrochloric acid, the mixture was heated in a pressure cooker at 105 ° C. under a pressure of 3 kg / cm ² for 1 hour. After cooling the treated product to 70 ° C., coarse gypsum such as soybean seed coat residue was roughly separated and removed using a centrifugal separator, and 10 g of powdered activated carbon was added to the obtained supernatant and stirred for 1 hour. Then, the mixture was filtered using a glass filter to obtain a transparent filtrate. This filtrate was neutralized with a 10% aqueous sodium hydroxide solution, and further dried under reduced pressure to remove water, thereby obtaining 125 g of the polysaccharide of the present invention. As a result of analyzing the sugar content of the polysaccharide, the uronic acid content (based on the weight of dry solids) was 33.2% by weight, and the hexose content (however, based on the weight of dry solids): 66.0% by weight. Was.

[0028]

According to the present invention, a polysaccharide having a high uronic acid content can be produced at a high yield by a simple method using soybean seed coat as a raw material. Soybean husks are generated as a large amount of by-products during the production of edible oil, and their use and use have been limited in the past. According to the present invention, a new use of soybean husks can be provided.

Claims (7)

[Claims] 1. A soybean seed coat is prepared by coexisting an acidic aqueous solution with
A process for producing a polysaccharide rich in uronic acid, which comprises heat-treating at 130 ° C. and then drying an aqueous solution from which insolubles have been removed, or adding a polar organic solvent to the aqueous solution to form a precipitate. 2. The method for producing a polysaccharide according to claim 1, wherein the polysaccharide contains uronic acid in an amount of 20% by weight or more. 3. The method for producing a polysaccharide according to claim 1, wherein the polysaccharide contains 20 to 50% by weight of uronic acid and 50% by weight or more of hexose. 4. The method for producing a polysaccharide according to claim 1, wherein the acidic aqueous solution contains hydrochloric acid and citric acid. 5. An acidic aqueous solution having a pH of 3 to 6.
Or the method for producing a polysaccharide according to 4. 6. The method for producing a polysaccharide according to claim 1, wherein the heat treatment is performed under pressure. 7. The method for producing a polysaccharide according to claim 1, wherein the heat treatment comprises heating to 100 to 120 ° C. under a pressure of 10 kg / cm ² or less.