JP5129921B2 - Diabetes rice grain and method for producing the same, cooked rice using diabetic rice grain and method for producing the same - Google Patents

Description

  The present invention relates to diabetic rice grains and cooked rice using the same. More specifically, the present invention relates to a diabetic rice grain having an anti-diabetic action that lowers blood glucose level or maintains blood glucose level within a certain range, and cooked rice using the same.

  Diabetes is the most serious problem in lifestyle-related diseases. According to the Ministry of Health, Labor and Welfare's 2002 Survey of Diabetes Mellitus, the total number of diabetics and the Preliminary Diabetes Army is estimated to be about 16.2 million, which is increasing. The increase in lifestyle-related diseases including diabetes is said to be caused mainly by changes in dietary habits, and in particular, increased fat intake and excessive intake of salt have been pointed out as major causes. Above all, the shortage of dietary fiber is considered to be deeply involved, and sufficient intake of dietary fiber is important for the prevention and treatment of lifestyle-related diseases, and the intake of 20-30 g per day is recommended.

  Dietary fiber includes insoluble dietary fiber composed of cellulose, hemicellulose, lignin, chitin, etc. and water-soluble dietary fiber composed of konjac mannan (glucomannan), guar gum (galactomannan), arabinoxylan, arabinogalactan, etc. Until now, it has not been decomposed by human digestive enzymes, has no nutritional value, and is regarded as a substance that inhibits the utilization efficiency of nutrients and has been treated as an unnecessary food. However, its effectiveness has gradually become clear and has attracted attention, such as improving intestinal flora, activating gastrointestinal motility, and reducing digestion and absorption of carbohydrates and lipids. Although the mechanism has not been clarified yet, short-chain fatty acids generated during fermentation by intestinal bacteria control hormone secretion in the body, affecting cholesterol synthesis and sugar metabolism in the liver. (J Am Diet Ass, 103 (1), 86-96, 2003, Diabetes care., 23 (1), 9-14, 2000, Am J Gastroenterol., 85, 549-553. 1990). In addition, it has been clarified that water-soluble dietary fiber has many physiological functions such as immunological activity and antitumor activity (Carbohydrr Polym., 25, 269-276, 1994, Phytochemistry, 27 (8)). 2511-2517, 1988). The essence of dietary fiber is polysaccharides, and among these polysaccharides, it is said that insoluble polysaccharides are required to have a high intake. In recent years, attention has been focused on water-soluble polysaccharides that are effective at lower volumes. Has been poured.

  So far, galactomannan (Nutr. Res., 20 (9), 1301-1307, 2000) and arabinoxylan (Clin. Expert. Pharm. Phys., 27 (1-2), 41-, which are water-soluble polysaccharides. 45, 2000) have been shown to have an anti-diabetic effect, but arabinogalactan, which is also a water-soluble polysaccharide, has been reported to have an immunostimulatory effect, with only a small amount of galactose ( Gal) has a β-1,3-linked galactan in the main chain, and β-arabinopyranose (Arap) and α-arabinofuranose (Araf) are α-1,3-linked oligosaccharides at the 6-position of the galactan And Araf and Gal are β-1,3 linked oligosaccharides, Gal and Gal are β-1,6 linked oligosaccharides bound as side chains. Arabinogalactan (AGII) is not only to report that it is effective in diabetes have been made (2001 IFT Annual Meeting).

  Although arabinogalactan is subdivided, it is roughly classified into two types. That is, it is classified into pectin arabinogalactan (hereinafter AG-I type) and arabino-3,6-galactan (hereinafter AG-II type). The former AG-I type has β-1,4-galactan with β-1,4-bonded galactose (Gal) in the main chain, and two α- at the 3-position of the Gal residue that is a component thereof. Oligosaccharide (α-Araf (5 → 1) α-Araf (5 →)) in which arabinofuranose (α-Araf) is α-1,5-linked. Most of these are obtained from sap of larch, acacia, etc., have an arabino-3,6-galactan structure in the main chain, and side chains composed of Araf, Gal, and the like are β-1,3 linked to the main chain. The composition ratio of Ara and Gal differs greatly depending on the plant species, but generally contains a large amount of Gal.In addition to Ara and Gal, which are the main constituent sugars, arabinogalactan includes fucose (Fuc). Rhamnose (Rha) , Xylose (Xyl), glucuronic acid (GlcUA), etc., and the structures thereof are very diverse, and AGIIa in the present invention has β-1,6-linked galactose β-1,6- An oligosaccharide (α-Araf (5 → 1) α having galactan in the main chain and α-Araf and two α-Araf linked to α-1,5 at the 3-position of the Gal residue which is a constituent component thereof. -Araf (5 →) or an oligosaccharide in which Gal or α-Araf and Gal are α-1,3 linked (α-Araf (1 → 3) α-Gal (1 →) is linked.

  Under these circumstances, diabetes treatment requires long-term self-management, so dietary therapy is the least burdensome and excellent, and taking into account side effects and ease of consumption, Development of diabetes drugs is desired.

The present applicant has already found that a specific arabinogalactan (particularly derived from white sweet potato) has an antidiabetic action on humans, and has filed an application (Japanese Patent Application No. 2004-135533) regarding an antidiabetic action substance. As a result of further intensive studies, it was found that a rice grain for diabetes having an antidiabetic action can be obtained by applying the above arabinogalactan to the rice grain, and the present invention has been completed.
The present invention has been made in view of the above circumstances, and provides a diabetic rice grain having an antidiabetic action that lowers blood glucose level or maintains blood glucose level within a certain range, and cooked rice using the same. Objective.

1. A method for producing a diabetic rice grain comprising immersing a rice grain in a solution of arabinogalactan and then drying the rice grain,
The above arabinogalactan is treated with a lower alcohol or a lower ketone on the aqueous extract of white sweet potato peel or tuberous root, and after removing the precipitate, the low molecular part of the aqueous solution from which the lower alcohol or lower ketone has been removed is removed. It was obtained by
When the arabinogalactan solution is 100% by mass, the content of the arabinogalactan is 1 to 20% by mass,
The immersion is performed by a reduced pressure treatment or a high pressure treatment,
Decompression degree when the pressure reducing process, - is at 0.05MPa or less,
The method for producing diabetic rice grains, wherein the pressure during the high-pressure treatment is 10 atm or more.
2. 2. The method for producing a rice grain for diabetes according to 1 above, wherein the immersion is performed by a high-pressure treatment of 10 atm or more.
3. The arabinogalactan has a skeleton in which β-1,6-linked galactose sugar chains are highly branched by β-1,3 bonds, and (1) α-arabinose is a side chain on the galactose constituting the skeleton. α-1,3 bond, or (2) α-arabinosyl (1 → 5) α-arabinose is α-1,3 bonded, and (3) α-rhamnosyl (1 → 4) β-glucuronic acid is the above skeleton. Β-1,6 bonds to part or all of the terminal galactose of
The composition ratio of rhamnose: glucuronic acid is 1: 0.7 to 1.2, the composition ratio of arabinose: galactose is 1: 1.8 to 2.3, and the composition ratio of rhamnose: arabinose is 1: 4. The manufacturing method of the rice grain for diabetes of said 1 or 2 which is 0.5-6.5.
4). The above arabinogalactan is treated with a lower alcohol or a lower ketone on the aqueous extract of white sweet potato peel or tuberous root, and after removing the precipitate, the low molecular part of the aqueous solution from which the lower alcohol or lower ketone has been removed is removed. And the manufacturing method of the rice grain for diabetes of any one of said 1 thru | or 3 which is obtained by refine | purifying the obtained fraction by weak basic ion exchange resin and / or gel filtration.
5. 5. The method for producing a rice grain for diabetes according to any one of 1 to 4 above, wherein the rice grain is brown rice, germ rice or polished rice.
6). The above 1 to 1 wherein the arabinogalactan solution further contains at least one functional substance among an α-amylase inhibitory substance, an α-glucosidase inhibitory substance, a glucose absorption inhibitory substance and a glucose metabolism promoting substance. The method for producing a rice grain for diabetes according to any one of 5.
7). 7. The method for producing a rice grain for diabetes according to 6 above, wherein the functional substance is at least one of pine fiber, mulberry leaf extract and arabinose.
8). The immersion is performed by a high pressure treatment of 10 atm or more,
The arabinogalactan has a skeleton in which β-1,6-linked galactose sugar chains are highly branched by β-1,3 bonds, and (1) α-arabinose is a side chain on the galactose constituting the skeleton. α-1,3 bond, or (2) α-arabinosyl (1 → 5) α-arabinose is α-1,3 bonded, and (3) α-rhamnosyl (1 → 4) β-glucuronic acid is the above skeleton. Β-1,6 bonds to part or all of the terminal galactose of
The composition ratio of rhamnose: glucuronic acid is 1: 0.7 to 1.2, the composition ratio of arabinose: galactose is 1: 1.8 to 2.3, and the composition ratio of rhamnose: arabinose is 1: 4. 5 to 6.5,
The above arabinogalactan is treated with a lower alcohol or a lower ketone on the aqueous extract of white sweet potato peel or tuberous root, and after removing the precipitate, the low molecular part of the aqueous solution from which the lower alcohol or lower ketone has been removed is removed. And the obtained fraction is purified by weakly basic ion exchange resin and / or gel filtration,
2. The method for producing a rice grain for diabetes according to 1 above, wherein the rice grain is brown rice or embryo rice.
9. 8. The solution according to 8 above, wherein the arabinogalactan solution further contains at least one functional substance among an α-amylase inhibitory substance, an α-glucosidase inhibitory substance, a glucose absorption inhibitory substance, and a glucose metabolism promoting substance. The manufacturing method of the rice grain for diabetes of description.
10. 10. The method for producing a rice grain for diabetes according to 9 above, wherein the functional substance is at least one of pine fiber and mulberry leaf extract.
11. 8. A diabetic rice grain obtained by the method for producing a diabetic rice grain according to any one of 1 to 7 above.
12 A diabetic rice grain obtained by the method for producing a diabetic rice grain according to any one of 8 to 10 above.
13. A cooked rice obtained by cooking the diabetic rice grain as described in 11 or 12 above, wherein the cooked rice is instant cooked rice, frozen cooked rice or dried cooked rice.
14 13. A method for producing cooked rice, comprising cooking rice grains for diabetes according to 11 or 12 above.

The diabetic rice grain of the present invention can be safely ingested because arabinogalactan that lowers blood sugar level or maintains blood sugar level within a certain range is given to the rice grain. Since arabinogalactan is a kind of water-soluble dietary fiber, like glycomannan and arabinoxylan, it can be expected not only to have antidiabetic activity but also to have the same effects as other dietary fibers, such as promoting defecation.
In addition, the function of at least one of an α-amylase inhibitory substance, an α-glucosidase inhibitory substance, a glucose absorption inhibitory substance, and a glucose metabolism promoting substance having an action mechanism different from the antidiabetic action of arabinogalactan When the substance is further provided, a superior antidiabetic action can be obtained.

The present invention will be described in detail below.
The method for producing a diabetic rice grain of the present invention is a method for producing a diabetic rice grain in which a rice grain is immersed in an arabinogalactan solution and then the rice grain is dried, wherein the arabinogalactan is a skin portion of white sweet potato Alternatively, the aqueous extract of the tuberous root is treated with a lower alcohol or a lower ketone, the precipitate is removed, and then the low molecular portion of the aqueous solution from which the lower alcohol or the lower ketone has been removed is removed. When the solution of nogalactan is 100% by mass, the content of the arabinogalactan is 1 to 20% by mass, and the immersion is performed by a reduced pressure treatment or a high pressure treatment. , - 0.05 MPa or less, the pressure at the time of the high-pressure process is characterized in that at least 10 atm.
Moreover, the rice grain for diabetes of this invention is obtained by the manufacturing method of this invention, and is provided with rice grain and the arabinogalactan which has the antidiabetic action provided to this rice grain.

  The “rice grain” is not particularly limited, and examples thereof include brown rice, germ rice, and polished rice. From the viewpoint of health, brown rice and germ rice are preferable, and brown rice is particularly preferable.

The "arabinogalactan," is an anti-diabetic action (e.g., action of lowering blood glucose level, effects such as to maintain a blood glucose level within a predetermined range) are those with a water-based skin portion or tuberous root portion of the white sweet potato The extract is obtained by treating the extract with a lower alcohol or lower ketone and removing the precipitate, and then removing the low molecular weight portion of the aqueous solution from which the lower alcohol or lower ketone has been removed .

In the present invention, the arabinogalactan has a skeleton in which β-1,6-linked galactose sugar chains are highly branched by β-1,3 bonds, and the galactose constituting the skeleton has (1) as a side chain. α-arabinose binds α-1,3, or (2) α-arabinosyl (1 → 5) α-arabinose binds α-1,3, and (3) α-rhamnosyl (1 → 4) β-glucuron The acid is β-1,6 bonded to a part or all of the terminal galactose of the skeleton, the composition ratio of rhamnose: glucuronic acid is 1: 0.7 to 1.2, and the composition ratio of arabinose: galactose May be 1: 1.8 to 2.3, and the composition ratio of rhamnose: arabinose may be 1: 4.5 to 6.5.
Specifically, galactose is composed of sugar chains in which β-1,6 bonds are formed, and has a basic skeleton as shown in FIG. 1 highly branched by β-1,3 bonds. That is, it has many side chains with β-1,3 linked oligosaccharides or galactoglycans with β-1,6 linked to galactose β-1,6 linked main chain. An oligosaccharide in which galactose is β-1,6-linked to a chain or a sugar chain in which galactose is β-1,6-linked is a β-1,6 It has a skeleton that is complicatedly branched by three bonds. As a result, it has a relatively bulky structure.

This arabinogalactan has three types of side chains (1), (2) and (3) as shown in FIGS. 2A and 2B with respect to the basic skeleton as shown in FIG. ) Are combined. The side chain (1) is a terminal α-arabinose (α-Araf), and the side chain (2) is an oligosaccharide [α-arabinosyl (1 → 5) α-arabinose, in FIG. 2, α-Araf (1 → 5) α-Araf (shown as 1 →), the side chain (3) is an oligosaccharide in which rhamnose is α-1,4 linked to glucuronic acid [Α-rhamnosyl (1 → 4) β-glucuronic acid, in FIG. 2, α-Rha (1 → 4) β-GlcUA (denoted as 1 →), wherein the side chains (1) and (2) are respectively Β-1,3 is bonded to the galactose constituting the skeleton, and the side chain (3) is glucuronic acid bonded to galactose forming the skeleton, β-1,6.
The binding position of the side chains (1), (2) and (3) and the branching position of the galactose sugar chain are not particularly limited, but about 65 to 75% of the galactose constituting the skeleton contains the side chain (1) and It is preferable that the side chain (2) is bonded and the side chain (3) is bonded to about 5 to 10% of the galactose constituting the skeleton.

  That is, as shown in FIG. 1, this arabinogalactan has a β-1,6-linked glycerin-linked sugar chain, and galactose-linked β-1,6-linked glycans by β-1,3 bonds everywhere. As shown in FIGS. 2 (A) and (B), the side chain (1) or (2) is branched to galactose of the sugar chain everywhere as shown in FIGS. As shown in FIG. 2 (B), it has a structure in which the side chain (3) is β-1,6 bonded to a part or all of the sugar chain terminal of galactose as shown in FIG.

  The average molecular weight of the arabinogalactan is not particularly limited, but is preferably about 10,000 to 500,000, more preferably about 50,000 to 500,000, and still more preferably about 100,000 to 200,000. In addition, this average molecular weight means the value calculated | required by the method described in the below-mentioned Example.

  Further, the composition ratio of each component constituting the arabinogalactan is such that rhamnose: glucuronic acid is 1: 0.7 to 1.2 (particularly 1: 0.7 to 1, more preferably 1: 0.8 to 0). .9), arabinose: galactose is 1: 1.8 to 2.3 (especially 1: 1.9 to 2.2, more preferably 1: 2 to 2.2), and rhamnose: arabinose is 1: It is preferably 4.5 to 6.5 (particularly 1: 5 to 6, and more preferably 5.3 to 5.8).

The arabinogalactan is extracted and separated from white sweet potato.
The above-mentioned white sweet potato has the scientific name “Ipomoea Batatas sp” and is a kind of Satsuma Mochi (herbaceous family “Ipomoea Batatas Poiret”), which is referred to as “Simon Mochi”, “Kaiapo Mochi”, “White Sweet Potato”, etc. Sometimes it is done. In the present invention, the skin portion or tuber portion of white sweet potato is used.

The arabinogalactan in the present invention can be obtained by concentrating the aqueous extract of white sweet potato peel or tuberous root and removing the precipitate, and before removing the precipitate, are facilities a lower alcohol or lower ketone process.
Furthermore, this arabinogalactan is a low molecular part of an aqueous solution from which the lower alcohol or lower ketone has been removed after the lower alcohol or lower ketone treatment is performed on the aqueous extract of the white sweet potato peel or tuberous root, and the precipitate is removed. It can be obtained by removing (for example, about 10,000 Da or less). In addition, the aqueous extract of white sweet potato peel or tuberous root is treated with lower alcohol or lower ketone, the precipitate is removed, and then the lower molecular portion of the aqueous solution from which the lower alcohol or lower ketone has been removed (for example, about 10000 Da or less) ) And the obtained fraction can be obtained by purification by weakly basic ion exchange resin and / or gel filtration. The aqueous extract may be a concentrated solution.

  Specifically, for example, it can be obtained by the method shown in FIG. First, white sweet potatoes, so-called dried pod skin, are crushed or powdered and water is added. Since arabinogalactan is considered to be mainly present in tuber skin, a tuber skin is preferably used as a raw material from the viewpoint of yield. Of course, the whole potato can be used as a raw material, and the ground stem or whole grass can be used. Similarly, when extracting from other plants or the like, a portion where a high yield is expected is preferably used.

Since arabinogalactan is a kind of water-soluble polysaccharide, an aqueous extraction solvent is first used in the same manner as extraction of other water-soluble polysaccharides. The extraction solvent is most preferably water, and may be a lower alcohol such as ethanol, a hydrophilic solvent such as acetone, or water obtained by adding such a hydrophilic solvent.
Moreover, you may heat and heat suitably at the time of extraction. The extraction method is not particularly limited, and the mixture is crushed and squeezed through a juicer, a mixer or the like, and then insoluble matters are removed by a centrifugal separation method, filtration, or the like. Alternatively, the extraction solvent may be added again to the residue once extracted and added to the previous extract. These are common methods for extracting polysaccharides.

  Next, the obtained extract is dialyzed against deionized exchange water. By dialyzing with deionized water, impurities such as low-molecular substances such as salts and monosaccharides in the extract are removed. The dialysis membrane to be used preferably has a molecular weight of about 12000 to 15000 Da or more. Smaller excretion (limit) molecular weight can sufficiently achieve the purpose, but it is disadvantageous because the dialysis time becomes longer. In addition, a dialysis membrane having a dialysis efficiency of about 12000 to 15000 Da, that is, one having a large number of dialysis holes per membrane is commercially available (for example, Spectra Biotech membrane / pore 2.1 manufactured by Funakoshi). This is because efficiency is desired. Moreover, since a precipitate may be generated by dialysis, the precipitate is appropriately removed by centrifugation or the like. Thus, impurities having a low molecular weight of about 10,000 Da or less are removed. Although this step is not an essential step, working efficiency in gel filtration chromatography, which is the following step, can be remarkably increased by performing this step. And refinement | purification is advanced further using the obtained dialysis internal solution. At this time, since the concentration in the dialysis internal solution cannot be said to be sufficiently high, it is preferable to perform concentration if necessary. Concentration is performed under reduced pressure using an evaporator or the like, preferably at a low temperature of about 40 ° C.

  Then, impurities other than the target substance are further precipitated and removed using lower alcohol or lower ketone in the obtained dialysis internal solution (concentrated solution). The lower alcohol is preferably ethanol, and the lower ketone is preferably acetone. This removal is repeated until no precipitation occurs even when alcohol or the like is added, and then the supernatant is separated to remove the solvent to obtain a crude extract. At this time, it is preferable to gradually increase the alcohol (ethanol, acetone) concentration, and the alcohol concentration should be at least 20 v / v% or more. Care must also be taken that the alcohol concentration does not exceed about 60 v / v%. If the alcohol concentration exceeds about 60 v / v%, the target substance may be precipitated. Therefore, it is added while paying attention to the alcohol concentration. Then, the supernatant is collected by centrifugation or the like and concentrated to obtain a crude extract. The arabinogalactan in the present invention has a relatively high content of rhamnose, which is a constituent sugar, so that precipitation is unlikely to occur even when the ethanol concentration is increased to about 60 v / v%. It should be noted that the target substance may precipitate even when the concentration is low (for example, it precipitates with 60 v / v% ethanol at a liquid temperature of 4 ° C.). Further, since the target product may precipitate if left for a long time, for example, about 48 hours, precipitation is preferably caused by standing for about 24 hours. This purification method is a general method for purifying polysaccharides, but in view of the high rhamnose content, alcohol is added to such an extent that arabinogalactan in the present invention does not precipitate, and impurities are almost precipitated and removed. In the final stage, the alcohol can be added at a high concentration, and the target product can be precipitated to obtain a crude extract.

  Then, this crude extract is further fractionated to obtain the desired arabinogalactan. Fractionation is performed by a combination of gel filtration chromatography and ion exchange chromatography.

  In the fractionation by gel filtration chromatography, as a filler, a trade name “Toyopearl HW-65S” (limit molecular weight dextran 700 to 1.3 million, Tosoh Corporation) and a trade name “Sephacryl S-400HR” (limit molecular weight dextran 1 to 200). , Globular protein 2-8 million, Amersham Biosciences Inc.). The eluent is preferably water, although it varies depending on the filler used. Then, each absorbance at a wavelength of 280 nm and a wavelength of 490 nm after color development with phenol sulfuric acid was measured for the eluate, and a peak corresponding to a molecular weight of about 100,000 to 200,000 Da showing no absorption in the ultraviolet region of wavelength 280 nm and absorption at 490 nm was determined. It is preferable to take.

Next, the fractionated material is further fractionated with an ion exchange resin to obtain arabinogalactan, which is a substantially single target substance. The ion exchange resin used at this time is, for example, a weakly basic ion exchange resin represented by “DEAE-Sephadex A50” (manufactured by Amersham Biosciences), “Amberlite IRA96SB”, “Amberlite IRA67” and the like. It is. The arabinogalactan trapped by the ion exchange resin is eluted with a strong ion electrolyte.
As this strong ion electrolyte, an aqueous sodium chloride solution having an ionic strength of 100 to 400 mM, preferably 150 to 300 mM, more preferably 170 to 230 mM, and particularly preferably 200 mM, or a ionic strength comparable to that is suitable. When the ionic strength exceeds 400 mM, there is a possibility that even a basic substance such as a protein other than the target substance is eluted together. Also in this fractionation, the absorbance at a wavelength of 280 nm of the eluate and a wavelength of 490 nm after color development with phenol sulfuric acid is used and fractionated as a fraction showing almost a single peak.

The collected eluate can be concentrated, for example, under reduced pressure, and then freeze-dried to obtain arabinogalactan as a substantially single substance in powder form.
The constituent ratio of the sugar is the ratio as described above. In order to actually use the substance as an anti-diabetic agent, both fractionation steps by gel filtration chromatography and ion exchange chromatography are not essential, and only one of gel filtration chromatography and ion exchange chromatography may be used. Although this step may be omitted, arabinogalactan with higher purity can be obtained by providing this step.

Moreover, the manufacturing method of the rice grain for diabetes of this invention can provide the said arabinogalactan to a rice grain by immersing the said rice grain in this arabinogalactan solution.
Examples of the solvent in the arabinogalactan solution include water, a mixed solution of water and a lower alcohol (for example, ethanol) or a lower ketone (for example, acetone). In particular, in the mass production of diabetic rice grains, it is preferable to use ethanol water having a concentration of 5 to 20% because the antibacterial and antifungal effects of the immersion liquid can be obtained.
The content of arabinogalactan in the solution, when the solution of arabinogalactan is 100 mass%, Ri 0.1-20% by mass, preferably 0.5 to 10 mass%, more preferably 1 -6% by mass, particularly preferably 3-6% by mass. When the content of this arabinogalactan is 0.1 to 20% by mass, a sufficient amount of arabinogalactan can be imparted.

Moreover, the conditions of the said immersion are a pressure reduction process or a high pressure process , and a high pressure process is especially preferable. In the case of high-pressure treatment, the arabinogalactan in the present invention is compatible with amylose contained in the rice grain, so that the complex of amylose and arabinogalactan is obtained by treatment at high pressure. It is formed and penetrates into the inside of the rice grain, and arabinogalactan can be sufficiently imparted not only on the surface of the rice grain but also inside.

The degree of pressure reduction during the vacuum treatment - 0.05 MPa or less, preferably - 0.07 MPa or less, more preferably - 0.09 MPa or less. The temperature is preferably 10 ° C or higher, more preferably 10 to 60 ° C, still more preferably 15 to 50 ° C, and particularly preferably 20 to 40 ° C. The treatment time is preferably 2 minutes or more, more preferably 2 to 60 minutes, still more preferably 5 to 40 minutes, and particularly preferably 10 to 30 minutes.
Furthermore, the pressure at the time of high-pressure treatment is 10 atm or more, preferably 10 to 8000 atm, more preferably 100 to 8000 atm, and particularly preferably 2000 to 6000 atm. The temperature is preferably 10 ° C or higher, more preferably 10 to 60 ° C, still more preferably 15 to 50 ° C, and particularly preferably 20 to 40 ° C. The treatment time is preferably 2 minutes or more, more preferably 2 to 60 minutes, still more preferably 5 to 40 minutes, and particularly preferably 10 to 30 minutes.

In the diabetic rice grain of the present invention, the rice grain includes at least one functional substance among an α-amylase inhibitory substance, an α-glucosidase inhibitory substance, a glucose absorption inhibitory substance, and a glucose metabolism promoting substance. Can be further provided. When these functional substances having an action mechanism different from that of the arabinogalactan are further added, it is preferable because a superior antidiabetic action can be obtained. In addition, as this functional substance, one in which each action is not deactivated at the time of rice cooking is appropriately selected and used.
Examples of the α-amylase inhibitory substance include polyphenols derived from guava, foseolan, and bay leaf extract.
Examples of the α-glucosidase inhibitory substance include bean lectin, polyphenol, mulberry leaf extract, arabinose, and soybean drum tris.
The glucose absorption inhibitory substance has an action of suppressing the absorption of glucose from the intestinal tract. Examples of the glucose absorption inhibitory substance include indigestible dextrin, kefiran, polydextrose, pectin, arabinoxylan, gluconomannan, galactomannan, pine fiber, and other mushroom-extracted polysaccharides derived from litchi and maitake , Gymnema extracts such as Gymnemic acid, and psyllium extracts such as Psyllium.
Examples of the glucose metabolism promoting substance include banaba extract such as corosolic acid.

  When the functional substance is further imparted to the rice grain, it may be dissolved or dispersed in advance in the arabinogalactan solution when the rice grain is immersed. Even if this functional substance is a polymer, if it is a substance compatible with amylose, the functional substance can be sufficiently applied not only to the surface of rice grains but also to the inside when subjected to high pressure treatment. .

  When adding a functional substance, the total content of the arabinogalactan and the functional substance is 20% by mass or less when the solution in which the arabinogalactan and the functional substance coexist is 100% by mass. More preferably, it is 0.5-10 mass%, More preferably, it is 1-6 mass%, Most preferably, it is 3-6 mass%. The content of arabinogalactan is usually 0.1% by mass or more. Therefore, the amount of arabinogalactan added to the immersion liquid can be reduced by the coexistence of the functional substance having an action mechanism different from that of arabinogalactan.

Moreover, the cooked rice of the present invention is obtained by cooking the above-described diabetic rice grains of the present invention, and the cooked rice is instant cooked rice, frozen cooked rice or dried cooked rice.
The above "instant cooked rice" is obtained by cooking the diabetic rice grain of the present invention and freeze-drying the obtained cooked rice or putting the diabetic rice grain of the present invention and water in a sealable pack and cooking with heat. be able to.
The “frozen cooked rice” can be obtained by cooking the diabetic rice grains of the present invention and rapidly freezing (eg, −15 ° C. or lower) the obtained cooked rice.
The “dried cooked rice” can be obtained by cooking the diabetic rice grains of the present invention and rapidly drying the obtained cooked rice by a method such as rapid hot air drying, freeze drying, expansion drying and the like.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to a following example.
[1] Preparation of diabetic rice grains (Examples 1 to 4)
[Example 1]
(1) Purification of arabinogalactan Arabinogalactan was obtained through a purification step according to FIG. First, 10 L of water was added to 1 kg of dried powder of white sweet potato peel (crushed skin), and the mixture was extracted by stirring at room temperature for 4 hours. The resulting mixture was centrifuged (7500 rpm / 30 minutes) and the residue was filtered off. Next, the obtained extract was dialyzed at room temperature for 3 days using deionized water. In the dialysis, the extract is put into a dialysis tube having a trade name “Dialysis Membrane Size 36” (pore size 24 mm, limit molecular weight 12000 to 14000 Da, manufactured by Wako Pure Chemical Industries, Ltd.). 6L was used by exchanging deionized water three times a day. And the insoluble part which arose in the dialysis internal solution was removed by centrifugation (7500 rpm / 30 minutes).

  The dialyzed internal solution from which the precipitate had been removed was concentrated by heating at about 40 ° C. with an evaporator, and then an appropriate amount of ethanol was added so that the concentration was about 20 v / v%, and the mixture was allowed to stand overnight at 4 ° C. The resulting precipitate was removed by centrifugation (7500 rpm / 30 minutes). Further, ethanol was added to the supernatant to adjust the alcohol concentration to about 40 v / v%, and the precipitate produced by standing as described above was removed. Then, ethanol is added again to adjust the alcohol concentration to about 60 v / v%, and the mixture is allowed to stand for one day and night (temperature: 4 ° C.). The supernatant is collected, concentrated, and freeze-dried to obtain a crude polysaccharide extract. (3.8 g) was obtained.

  The crude polysaccharide extract was subjected to gel filtration chromatography and ion exchange chromatography, and further purified. A 1 w / v% aqueous solution (1 g / 100 mL) of the crude polysaccharide extract was prepared, centrifuged (15000 rpm / 20 minutes), and the water-soluble portion was separated. This was fractionated using gel filtration chromatography. This fraction was prepared by using “Toyopearl HW-65S” (manufactured by Tosoh Corporation: 880 mL packed in a 4.5 × 700 cm column) as a carrier and water at a flow rate of 0.5 mL / min as an eluent at 15 mL / 1. Made in a tube. The eluate in this tube shows absorption at 490 nm by the phenol-sulfuric acid method (wavelength 490 nm) and UV absorption (280 nm), no absorption in the ultraviolet region of wavelength 280 nm, and corresponds to a molecular weight of about 100,000 to 200,000 Da. The peak to be collected was collected.

  Next, the seeded extract was subjected to ion exchange chromatography and further purified. Using “DEAE-Sephadex A-50” (manufactured by Amersham Biosciences) as an ion exchange resin, the extract was loaded and then eluted with a 200 mM sodium chloride aqueous solution. Elution was performed at a flow rate of 0.5 mL, and the eluate was collected in a 15 mL / 1 tube. The eluate in this tube shows absorption at 490 nm by the phenol-sulfuric acid method (wavelength 490 nm) and UV absorption (280 nm), no absorption in the ultraviolet region of wavelength 280 nm, and corresponds to a molecular weight of about 100,000 to 200,000 Da. The peak to be collected was collected. The yield of the obtained extract relative to the dried white sweet potato peel was about 0.09%.

  Next, the molecular weight and molecular size of the above components were measured using a multi-angle light scattering detector (MALLS) and size exclusion chromatography (SEC). The measurement conditions are as follows. The column used was OH-pak SB-806MHQ (manufactured by Showa Denko KK), the detector was a multi-angle light scattering detector DAWN • E (manufactured by Wyatt), and a differential refractive index detector RI-8020 (manufactured by Tosoh Corporation). The column temperature is room temperature (25 ° C.), the mobile phase is 200 mM NaCl aqueous solution, the sample concentration is 1 mg / mL (dissolved in the mobile phase), the flow rate is 0.5 mL / min, and the injection volume is 100 μL. During injection, a syringe filter (pore size 0.2 μm) was attached to the syringe, and injection was performed while filtering. The result is shown in FIG. As can be seen from FIG. 4, the retention time of this material was about 19 minutes, which was almost a single peak. The molecular weight of this product was about 100,000 when it was small and about 200,000 when it was large, and its average molecular weight was about 130,000. The molecular weight distribution has a narrow width of about 200,000, and is a high-purity and relatively homogenous showing an almost single peak. In addition, the average molecular weight here means the average molecular weight in a single peak showing the substance obtained by measurement using the above measuring apparatus.

  The structure of arabinogalactan in the present invention was confirmed as follows. First, the composition ratio of the constituent sugars was examined. About the 200 mM elution fraction by ion exchange chromatography, the sugar composition was confirmed by HPAEC-PAD method after complete hydrolysis with formic acid and trifluoroacetic acid. The measurement conditions are as follows. The column used is CarboPac PA-1 (4 × 250 mm: manufactured by Nippon Dionex Co., Ltd.), elution is 0.2M NaOH (0 → 5 minutes), linear gradient 0 → 0.45M sodium acetate (in 0.2N NaOH / 5 → 35 min), the flow rate is 1.0 mL / min, and the detector is a pulsed amperometry detector. The results are shown in FIG. As a result, it was confirmed that Rha, Ara, Gal, and GlcUA were configured at a ratio of 1.2: 6.7: 14.1: 1.0.

  Next, the partial methylation analysis was performed about the elution fraction by 200 mM sodium chloride aqueous solution. Analysis is performed using a gas mass analyzer (GC-17A, GCMS-QP5000: manufactured by Shimadzu Corporation), a DB-225GC column (manufactured by J & W Scientific: 0.25 μm × 30 m × 0.25 μm), 170 ° C., 5 minutes, 170 → This was carried out under the conditions of a vaporization chamber temperature of 230 ° C. and a detector temperature of 230 ° C. under a column temperature increase program of 210 ° C. (temperature increase rate: 2 ° C./min). The results are shown in FIG.

  As understood from FIG. 6 and Table 2, arabinogalactan in the present invention is terminal α-Araf or terminal Rha (peak 1) and terminal Gal (peak 3), α-Araf having 1,5 bonds (peak). 2) Gal having 1,3 bonds (peak 5), Gal having 1,6 bonds (peak 7), Gal having 1,3,6 bonds (peak 8) and GaI having 1,3,5 bonds It was confirmed that the compound has 8 types of binding (peak 4). In addition, although the peak derived from Rha is not detected, it is thought that the retention time with the terminal Araf was very close and both were detected at the same position without being sufficiently separated.

Next, various NMR spectra ( ¹ H, ¹³ C-NMR, ¹ H- ¹ HCOSY, HOHAHA, HMQC, HMBC) were analyzed in order to confirm the linkage of each sugar. First, the chemical shift of each sugar was confirmed. The results are shown in Table 3. Furthermore, HMBC analysis (see FIG. 7) was performed based on this result, and the partial structure and sugar chain linkage shown in FIG. 2 were confirmed. That is, Gal (galactose) has a galactose chain branched by β-1,3 bonds in a β-1,6 linked galactose chain, and (1) terminal α-arabinose (α -Araf) or (2) two monosaccharide oligosaccharides [α-arabinosyl (1 → 5) α-arabinose, in which two arabinoses (arabinofuranose) are α-1,5 linked, α-Araf in FIG. (1 → 5) α-Araf (denoted as 1 →) is β-1,3 linked, and (3) a bisaccharide oligosaccharide [α-rhamnosyl (α-rhamnosyl) in which rhamnose is α-1,4 linked to glucuronic acid 1 → 4) β-glucuronic acid, in FIG. 2, α-Rha (1 → 4) β-GlcUA (denoted 1 →) is β-1,6 linked to 5-10% of its galactose.

(2) Anti-diabetic action of arabinogalactan (confirmation of hypoglycemic action)
The hypoglycemic effect test was performed using 5-week-old db / db mice (male). Breeding environment is a 12 hour period of light-dark cycle from 7: 00-19: 00 lighting ON, temperature 23-24 ° C, humidity 60-70% RH, pre-breeding for 1 week before the test, The values were divided into 2 groups (6 animals in each group) so that no significant difference was found between groups. The administration group was divided into a non-administration group (physiological saline) and an arabinogalactan administration group (20 mg / kg) obtained in (1) above. Administration was oral for 5 weeks with a sonde. During the test period, both feed and drinking water were ad libitum. Blood was collected from the mouse tail vein before administration and every week after the start of administration, and the blood glucose lowering action was confirmed using the obtained serum. The measurement results are shown in Table 4.

(Confirmation of glucose tolerance improving effect)
After confirming the hypoglycemic action, glucose was orally administered to each group at 2 g / kg, and blood was collected from the tail vein of the mouse over time (before glucose load), 60 minutes, and 120 minutes. The change with time was examined. The results are shown in Table 5. This test was conducted after 12 hours of fasting after the end of the hypoglycemic effect test.

  From the results of Tables 4 and 5, it was confirmed that the arabinogalactan in this example has a hypoglycemic action and a glucose tolerance improving action.

(3) Application of arabinogalactan to rice grains (high pressure treatment)
A 3% by mass aqueous solution was prepared by dissolving arabinogalactan purified according to the method of (1) above in water. Thereafter, 150 ml of this aqueous solution and 100 g of unwashed polished white rice or brown rice are put in separate sealed plastic bags, sealed, and then put into a pressure machine (made by Ishikawajima-Harima Heavy Industries Co., Ltd.) filled with water. High pressure treatment was performed under conditions of a treatment time of 10 minutes. After restoring the pressure, the contents were opened in a colander, and the rice grains excluding the immersion liquid were dried to obtain diabetic rice grains.
Moreover, content of the arabinogalactan of the obtained rice for diabetes was measured by the method of the below-mentioned. As a result, the arabinogalactan content in diabetic rice grains using polished rice was 1.8% by mass. Moreover, content of the arabinogalactan in the rice grain for diabetes using brown rice was 3.1 mass%.

(Measurement of arabinogalactan content)
The content of the arabinogalactan was measured as follows according to an official method of AOAC (Association of Official Agricultural Chemistry).
1 g of rice grains to which arabinogalactan has been added is placed in a tall beaker, 50 ml of 0.08 M phosphate buffer (pH 6.0) and 0.1 ml of Termamyl 120 L (manufactured by Novozymes) are added and reacted in a boiling water bath for 30 minutes. After standing to cool, the pH is adjusted to 7.5 using 0.275 M NaOH, 5 mg of protease P-5380 (manufactured by Sigma) is added, and the mixture is reacted at 60 ° C. for 30 minutes with shaking. After cooling, the pH is adjusted to 4.3 with 0.325 M HCl, 0.1 ml of amyloglucosidase solution A-9913 (manufactured by Sigma) is added, and a shaking reaction is performed at 60 ° C. for 30 minutes. After completion of the reaction, 95% ethanol heated to 60 ° C. is added in an amount 1.5 times the amount of the reaction completed solution, left to stand at room temperature for 1 hour, and then suction filtered using Celite 545. The filtration residue is washed 3 times with 20 ml of 60% ethanol water and 3 times with 10 ml of 95% ethanol, and all the filtrate is recovered and concentrated in an evaporator. After adding glycerin to be used as an internal standard and filling up to 100 ml (using water), 50 ml of the solution was desalted, and 10 ml of the liquid obtained by evaporating the solution was filtered through a 0.45 μm membrane filter and analyzed by HPLC ( Column: ULTRON PS-80N, manufactured by Shinwa Kako Co., Ltd., temperature: 80 ° C., mobile phase: water, flow rate: 0.3 ml / min, detection: differential refractometer, sample injection amount: 20 μl). Analyzing the arabinogalactan used in advance and calculating the amount of arabinogalactan on the HPLC and the peak ratio of the internal standard with reference to the elution position and the amount of internal standard added and the peak area as an index To obtain the water-soluble dietary fiber content.
The rice grains used for the arabinogalactan application operation are subjected to the same analysis operation as above for the rice grains pressure-treated without adding arabinogalactan, and the obtained water-soluble dietary fiber content is subtracted from the above value. The content of arabinogalactan was determined by pulling.

[Comparative Example 1] and [Example 2] (Difference in the amount of arabinogalactan applied by the dipping method)
[Comparative Example 1]
(Normal pressure treatment)
In a plastic bag that can be sealed, 150 ml of a 3% by weight arabinogalactan aqueous solution prepared in the same manner as in Example 1 and 100 g of unwashed polished white rice were placed and sealed, and immersed under conditions of a temperature of 25 ° C. and a treatment time of 30 minutes. Then, it opened, the contents were opened to the colander, the rice grain except the immersion liquid was dried, and the rice grain for diabetes was obtained. Next, the content of arabinogalactan in the obtained diabetic rice grains was measured in the same manner as described above. As a result, the arabinogalactan content of this diabetic rice grain was 1.0% by mass.
[Example 2]
(Decompression treatment)
150 ml of 3% by mass arabinogalactan aqueous solution prepared in the same manner as in Example 1 and 100 g of unwashed polished white rice were placed in a tray (20 cm × 20 cm × 10 cm), and this tray was a desiccator equipped with a vacuum meter (removing the desiccant). to put off at a vacuum machine (ULVAC DA-20D, manufactured by ULVAC KIKO, Inc.), the degree of vacuum - 0.06 to - 0.07 MPa, temperature of 25 ° C., a reduced pressure treatment was carried out under conditions of processing time of 10 minutes (Note, During the decompression process, the desiccator was vibrated twice to remove bubbles attached to the rice grains. Subsequently, after returning to normal pressure, the tray was taken out from the desiccator, opened in a colander, and the rice grains were separated, and the rice grains were dried to obtain diabetic rice grains. Thereafter, the content of arabinogalactan in the obtained diabetic rice grains was measured in the same manner as described above. As a result, the arabinogalactan content of this diabetic rice grain was 1.2% by mass.
(High pressure treatment)
In a plastic bag that can be sealed, 150 ml of a 3% by weight arabinogalactan aqueous solution prepared in the same manner as in Example 1 and 100 g of unwashed polished white rice were sealed and sealed in a pressurizer (made by Ishikawajima-Harima Heavy Industries Co., Ltd.) filled with water. Then, high pressure treatment was performed under the conditions of 1000 atm, temperature of 25 ° C., and treatment time of 10 minutes. After restoring the pressure, the contents were opened in a colander, and the rice grains excluding the immersion liquid were dried to obtain diabetic rice grains. Thereafter, the content of arabinogalactan in the obtained diabetic rice grains was measured in the same manner as described above. As a result, the arabinogalactan content of this diabetic rice grain was 1.4% by mass.
From the above, it was found that the highest amount of arabinogalactan can be imparted to rice grains when subjected to high pressure treatment.

[Example 3] (arabinogalactan + pine fiber (glucose absorption inhibitory substance))
An aqueous solution obtained by dissolving 3.0 g of pine fiber (manufactured by Matsutani Chemical Industry Co., Ltd.) in 150 ml of a 1.5% by mass arabinogalactan aqueous solution prepared in the same manner as in Example 1 and 100 g of brown rice were placed in a sealed plastic bag, and the test was carried out. High pressure treatment was performed in the same manner as in Example 1. Next, the content of arabinogalactan and pine fiber in the diabetic rice grains was measured in the same manner as described above (note that the content of pine fiber can also be measured using the same method as in the case of arabinogalactan). . The total content of arabinogalactan and pine fiber in the obtained rice grains for diabetes was 4.1% by mass.

[Example 4] (arabinogalactan + mulberry leaf extract (α-glucosidase inhibitory substance))
50 g of dried mulberry leaves are placed in 1 L of boiling water and left at room temperature for 5 minutes with occasional stirring. The filtrate is obtained by filtration, and the filtrate is concentrated under reduced pressure with an evaporator. The resulting precipitate is removed by centrifugation to obtain a supernatant, and water is added to fill up to 50 ml. In a plastic bag, 10 ml of this concentrated solution, 140 ml of 3% by mass arabinogalactan aqueous solution, and 100 g of polished rice are sealed. Water is applied to the high-pressure processor and the plastic bag is submerged for high-pressure processing. High-pressure treatment was performed under conditions of a liquid temperature of 20 ° C., 4000 atm, and a treatment time of 10 minutes. After restoring the pressure, the contents of the plastic bag were opened in a colander to remove the immersion liquid, and dried with a dryer to obtain rice grains for diabetes. Thereafter, the content of arabinogalactan in the obtained diabetic rice grains was measured in the same manner as described above. As a result, the arabinogalactan content of this diabetic rice grain was 1.6% by mass.
Further, α-glucosidase inhibitory activity was measured by the following method, and 1 g of diabetic rice grains inhibited α-glucosidase activity by 90% or more.

(Method for measuring α-glucosidase inhibitory activity)
0.4 ml of 4% sucrose aqueous solution and 0.5 ml of enzyme solution (Preparation method: 15 mg of 0.1 M phosphate buffer, pH 6.5 was added to 50 mg of α-glucosidase acetone powder (Sigma) and subjected to ultrasonic treatment. And 0.1 ml of water or aqueous solution of inhibitor (preparation method: 1 g of treated rice is put in a mortar and crushed well, then 5 ml of water is added and suspended, and centrifugal sedimentation is performed. The obtained supernatant is used.) And the mixture is reacted at 37 ° C. for 30 minutes. The reaction was completed by adding 0.1 ml of the above reaction solution to 0.1 ml of 0.05N NaOH solution, and 3 ml of glucose CII-Test Wako (Wako Pure Chemical Industries, Ltd.) was added to 0.1 ml of this reaction stop solution. , U-3010 spectrophotometer (manufactured by Hitachi, Ltd.) was used according to a predetermined method.
_{Inhibition% = {(A 30 -A 0} ) - (S 30 -S 0)} × 100 / (A 30 -A 0)
A ₃₀ : Absorbance after 30 minutes of reaction when water is used instead of the aqueous inhibitor solution A ₀ : Absorbance after 0 minute of reaction when water is used instead of the aqueous inhibitor solution S ₃₀ : Inhibitor aqueous solution is contained Absorbance at 30 minutes after reaction S ₀ : Absorbance at 0 minutes when aqueous inhibitor solution was added

[Example 5] (arabinogalactan + arabinose (α-glucosidase inhibitory substance))
A solution prepared by adding 3 g of L-arabinose (manufactured by Wako Pure Chemical Industries, Ltd.) to 150 ml of a 3% by mass arabinogalactan aqueous solution prepared in the same manner as in Example 1 and 100 g of unwashed polished white rice are placed in a sealed plastic bag. Te, the temperature 30 ° C., vacuum degree - 0.06 to - 0.07 MPa, treatment time subjected to vacuum treatment at 10 minutes, thereby the rice grains for diabetes by drying except immersion liquid. The contents of arabinogalactan and arabinose in this rice grain were 1.3% by mass and 1.6% by mass, respectively. The arabinogalactan content was measured in the same manner as described above. The content of arabinose was measured as follows.

(Measurement of arabinose content)
In the method for measuring the content of arabinogalactan, all operations are performed in the same manner except that the column temperature under the HPLC operation conditions is 60 ° C. and the sample injection amount is 10 μl.
Then, after confirming the elution position of L-arabinose (RT is about 8 minutes), the sample was fed, and the rice grains used for the application operation and the rice grains after the application were the same R.A. T.A. The content of the position was determined, and the content of arabinose was determined from the difference between the values.

[3] Preparation of processed cooked rice Each processed cooked rice was prepared as follows using the diabetic rice grains obtained in the same manner as in Example 1 of [1] above.
(1) Instant cooked rice The above-mentioned diabetic rice grains and water were put into a sealable container and cooked with heating to obtain instant cooked rice.
(2) Frozen cooked rice The above-mentioned rice for diabetes was cooked, and the obtained cooked rice was rapidly frozen at -15 to -40 ° C to obtain frozen cooked rice.
(3) Dry rice rice The above-mentioned rice grains for diabetes were cooked, and the obtained cooked rice was rapidly hot-air dried to obtain dry rice.

  Each of the above-mentioned processed cooked rice is considered to have an excellent anti-diabetic action because it uses the rice grains for diabetes of the present invention.

It is a figure which shows the basic skeleton of arabinogalactan which concerns on this invention. It is a figure which illustrates the coupling | bonding mode of the side chain to the basic skeleton of arabinogalactan based on this invention. It is a figure which shows the outline of the refinement | purification process of the arabinogalactan based on this invention. It is an analysis chart by MALLS-SEC of a 200 mM NaCl fraction in ion exchange chromatography. The dotted line in the figure shows the molecular weight distribution of arabinogalactan. It is an analysis chart by HPAEC-PAD of 200 mM NaC / fraction in ion exchange chromatography. It is an analysis chart by GS-MS of 200 mM NaC / fraction in ion exchange chromatography. It is a HMBC analysis figure of arabinogalactan concerning the present invention.

Claims (14)

A method for producing a diabetic rice grain comprising immersing a rice grain in a solution of arabinogalactan and then drying the rice grain,
The above arabinogalactan is treated with a lower alcohol or a lower ketone on the aqueous extract of white sweet potato peel or tuberous root, and after removing the precipitate, the low molecular part of the aqueous solution from which the lower alcohol or lower ketone has been removed is removed. It was obtained by
When the arabinogalactan solution is 100% by mass, the content of the arabinogalactan is 1 to 20% by mass,
The immersion is performed by a reduced pressure treatment or a high pressure treatment,
Decompression degree when the pressure reducing process, - is at 0.05MPa or less,
The method for producing diabetic rice grains, wherein the pressure during the high-pressure treatment is 10 atm or more.   The said immersion is a manufacturing method of the rice grain for diabetes of Claim 1 performed by the high pressure process of 10 atmospheres or more. The arabinogalactan has a skeleton in which β-1,6-linked galactose sugar chains are highly branched by β-1,3 bonds, and (1) α-arabinose is a side chain on the galactose constituting the skeleton. α-1,3 bond, or (2) α-arabinosyl (1 → 5) α-arabinose is α-1,3 bonded, and (3) α-rhamnosyl (1 → 4) β-glucuronic acid is the above skeleton. Β-1,6 bonds to part or all of the terminal galactose of
The composition ratio of rhamnose: glucuronic acid is 1: 0.7 to 1.2, the composition ratio of arabinose: galactose is 1: 1.8 to 2.3, and the composition ratio of rhamnose: arabinose is 1: 4. It is 0.5-6.5, The manufacturing method of the rice grain for diabetes of Claim 1 or 2.   The above arabinogalactan is treated with a lower alcohol or a lower ketone on the aqueous extract of white sweet potato peel or tuberous root, and after removing the precipitate, the low molecular part of the aqueous solution from which the lower alcohol or lower ketone has been removed is removed. The method for producing diabetic rice grains according to any one of claims 1 to 3, wherein the obtained fraction is purified by weakly basic ion exchange resin and / or gel filtration.   The method for producing a rice grain for diabetes according to any one of claims 1 to 4, wherein the rice grain is brown rice, germ rice, or polished rice.   2. The arabinogalactan solution further contains at least one functional substance selected from an α-amylase inhibitory substance, an α-glucosidase inhibitory substance, a glucose absorption inhibitory substance, and a glucose metabolism promoting substance. The manufacturing method of the rice grain for diabetes of any one of thru | or 5.   The method for producing a rice grain for diabetes according to claim 6, wherein the functional substance is at least one of pine fiber, mulberry leaf extract and arabinose. The immersion is performed by a high pressure treatment of 10 atm or more,
The arabinogalactan has a skeleton in which β-1,6-linked galactose sugar chains are highly branched by β-1,3 bonds, and (1) α-arabinose is a side chain on the galactose constituting the skeleton. α-1,3 bond, or (2) α-arabinosyl (1 → 5) α-arabinose is α-1,3 bonded, and (3) α-rhamnosyl (1 → 4) β-glucuronic acid is the above skeleton. Β-1,6 bonds to part or all of the terminal galactose of
The composition ratio of rhamnose: glucuronic acid is 1: 0.7 to 1.2, the composition ratio of arabinose: galactose is 1: 1.8 to 2.3, and the composition ratio of rhamnose: arabinose is 1: 4. 5 to 6.5,
The above arabinogalactan is treated with a lower alcohol or a lower ketone on the aqueous extract of white sweet potato peel or tuberous root, and after removing the precipitate, the low molecular part of the aqueous solution from which the lower alcohol or lower ketone has been removed is removed. And the obtained fraction is purified by weakly basic ion exchange resin and / or gel filtration,
The method for producing a rice grain for diabetes according to claim 1, wherein the rice grain is brown rice or germinated rice.   9. The arabinogalactan solution further contains at least one functional substance selected from an α-amylase inhibitory substance, an α-glucosidase inhibitory substance, a glucose absorption inhibitory substance, and a glucose metabolism promoting substance. The manufacturing method of the rice grain for diabetes as described in 2.   The method for producing a rice grain for diabetes according to claim 9, wherein the functional substance is at least one of pine fiber and mulberry leaf extract.   A diabetic rice grain obtained by the method for producing a diabetic rice grain according to any one of claims 1 to 7.   A rice grain for diabetes obtained by the method for producing a rice grain for diabetes according to any one of claims 8 to 10.   A cooked rice obtained by cooking the diabetic rice grain according to claim 11 or 12, wherein the cooked rice is instant cooked rice, frozen cooked rice or dried cooked rice.   The manufacturing method of the cooked rice which cooks the rice grain for diabetes of Claim 11 or 12.

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