JP2009232857A - Method for producing rice protein, rice protein produced by the method, and food - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing rice protein including fractionating rice protein under safe conditions without using any chemicals or medicaments undesirable for intake into human bodies. <P>SOLUTION: The method for producing rice protein includes: adding a reaction-system enzyme liquid to rice, rice powder and/or rice bran; subjecting the obtained reaction liquid to centrifugal separation to collect precipitates; precipitating starch by a sucrose gradient centrifugal separation method to eliminate the starch; subjecting the obtained solution to pepsin digestion; subjecting the digestive fluid to centrifugal separation to collect precipitates; and dialyzing the precipitates to fractionate the prolamin. The thus obtained rice protein is used as food simply or as part of food, or dried and pulverized to be utilized as food material. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rice protein obtained by fractionation from rice, rice flour and / or rice bran, a method for producing the same, and a food using the rice protein.

  In general, it has been well known for a long time that plant proteins have various physiologically functional substances such as plasma cholesterol lowering action. In particular, with the increase in lifestyle-related diseases in recent years, awareness of food and health has increased, and the physiological functionality of food has attracted attention. Many of the vegetable proteins conventionally used are legume proteins such as soybeans and wheat proteins. The method of fractionating and extracting these proteins from raw materials is widely used not only for the production of traditional foods such as tofu, yuba, and salmon, but also for various processed foods (see, for example, Non-Patent Document 1). .

  Rice, which is a key crop in Japan, contains protein that accounts for 6 to 10% of the weight of brown rice, and in addition to main glutelin and prolamin, there are also small amounts of albumin and globulin. Most of the rice protein exists in endosperm and accumulates in intracellular granules called two types of protein bodies (PB). One protein body (PB-I) is known to specifically accumulate prolamin and the other protein body (PB-II) contains the most abundant glutelin (for example, non-protein body). (See Patent Documents 2 and 3).

There are various methods for fractionating plant proteins, but none are universally available. In practice, these methods are usually combined in accordance with the properties of the raw materials and the purpose of fractionation. (For example, see Non-Patent Document 4). For example, when the raw material is solid, after disrupting the cell wall and cell membrane by pre-treatment such as grinding, water, neutral salt solution, buffer solution, dilute acid, dilute alkali, alcohol, etc. depending on the raw material and purpose The protein is extracted using a suitable solvent, and the target protein is separated and purified by methods such as filtration / centrifugation, dialysis, concentration, freeze-drying, salting out, precipitation with an organic solvent, and electrophoresis.

  It is well known that rice glutelin is soluble in dilute acids and alkalis, and that rice prolamin is soluble in 60-90% alcohol. Therefore, conventionally, the rice protein fractionation method is generally a method combining solvent extraction with a dilute acid or dilute alkali solution and salting out with ammonium sulfate.

For example, and extracted by adding sodium chloride solution to rice grain powder, extract was centrifuged to precipitate the total protein added ammonium sulfate to supernatant, the precipitate was dialyzed suspended in water and centrifuged In addition, a method is known in which the obtained supernatant is classified as albumin and the precipitate is classified as globulin (see, for example, Non-Patent Documents 5 and 6). Further, in this method, the precipitate obtained by the first centrifugation is extracted by adding ethyl ether, the extract is centrifuged, the supernatant is the residue from which alcohol is removed, and the precipitate is NaOH. The precipitate obtained by using acetic acid in the extract obtained by centrifugation is classified as glutelin.

  Protein extraction with dilute acid As a method of protein extraction by dilute acid, rice, rice flour or white birch is absorbed and steamed and then immersed in 0.05 to 5% solution of lactic acid, etc. A method for selectively extracting only -II) is known (for example, see Patent Document 1). According to the patent document, in the lactic acid immersion test, only PB-II is eluted in atmospheric steamed rice, the amount is about 10% of the total protein of white rice, and the decomposition of PB-II is suppressed. It has been confirmed that in the case of pressurized steamed rice by autoclaving, there is almost no protein elution by lactic acid. Further, according to the patent document, when raw rice is used, both PB-I and PB-II are extracted, and only PB-II cannot be selectively extracted, and a part of PB-II is partially extracted. It is said that it has been disassembled.

  In addition, a method for producing rice protein by enzyme treatment has been proposed. For example, in order to obtain high-purity rice protein in a short time and high yield by a simple operation, rice bran and heat-resistant α-amylase are dispersed and dissolved in water, and this aqueous solution is heated to heat-resistant α-amylase. A method for producing rice protein is known in which starch in rice bran is digested by action, solids are separated from the digest and dried (see, for example, Patent Document 2).

  Furthermore, a method is known in which rice bran, crushed rice, or rice grain is enzymatically treated to produce stepwise a cyclodextrin, glucose for fermentation raw material, and a high protein rice grain fraction (see, for example, Patent Document 3). This method makes it possible for enzymes produced by Bacillus thermophilic bacteria to efficiently produce cyclic dextrin (cyclodextrin: CD) using rice bran and crushed rice as raw materials, and to easily produce high-purity glucose from the mother liquor from which the produced CD has been separated. It is based on the fact that lactic acid is efficiently produced when this glucose is used as a raw material for lactic acid fermentation. In this method, for example, an enzyme produced from a thermophilic Bacillus genus, cyclodextrin / glucanotransferase (CGTase) is added to and reacted with a raw material liquid obtained by adding and kneading rice bran and reacting it. Protein-enriched rice flour is obtained from the precipitate obtained by centrifugation.

  Conversely, the rice soaked in water is ground to form a rice emulsion, left for a predetermined period of time to leave the water-soluble protein in the water, and the sedimented fraction is collected, or the rice is brought into contact with lactic acid bacteria or protease. Thus, a method for removing water-soluble protein has been proposed (see, for example, Patent Document 4).

“Overview of Plant Food Science”, [online], late 2004, Food Chemistry Laboratory, Department of Food and Health Science, Department of Agricultural and Life Sciences, Faculty of Agriculture, Iwate University, [Search April 19, 2005], Internet <URL: http: / /news7a1.atm.iwate-u.ac.jp/~food-c/sylla/syokugai.htm> Satoshi Suzuki, 2 others, “Food Ingredient Series Protein Science”, first edition, Asakura Shoten Co., Ltd., November 1998, p. 149-150 Kunisuke Tanaka, 1 other author, “Dissecting the taste of Kyoto”, first edition, Jinshoin, November 2004, p. 168-171 Tetsujiro Ohara, supervised by two others, “Revised Food Analysis Handbook”, revised edition, Kenshisha Co., Ltd., June 1989, p. 55-59 Kyoto University Faculty of Agriculture, Department of Food Engineering, “Food Engineering Experiments (Vol. 1)”, Correction 2nd Edition, Yokendo Co., Ltd., January 1975, p. 602-603 Department of Agricultural Chemistry, Faculty of Agriculture, Kyoto University, “New Revised Agricultural Chemistry Experiment (Supplement) Volume 2”, First Edition, Sangyo Tosho Co., Ltd., March 1978, p. 568-571 JP-A-9-249695 JP-A-6-197699 JP-A-6-253880 JP 2002-153215 A

  As mentioned above, rice protein, which is a vegetable protein containing a lot of useful substances, is promoted to health by ingesting it as a food, and the development of new health foods with high added value has led to a decrease in rice protein. Expected to increase consumption. However, in reality, rice protein is not necessarily fully utilized, and as far as the inventors of the present application know, there are traditional foods produced from rice protein and processed foods using fractionated rice protein. can not see.

  Further, conventionally known methods for fractionating rice protein use a large amount of reagents such as ammonium sulfate, which are not necessarily preferable for the human body when the obtained protein is ingested as food. That is, these conventional methods are basically intended for use in a laboratory, and none of them is a method intended to use a protein obtained after fraction purification as a food.

  On the other hand, the method for extracting rice storage protein described in Patent Document 1 uses a dilute acid such as lactic acid, and thus has high safety and can be widely used for various materials for food and medicine. Only II is extracted, and other proteins cannot be fractionated. Moreover, the process of steaming rice etc. is required as a pretreatment of the raw material, and it is difficult to efficiently produce a large amount of rice protein.

  Similarly, the method described in Patent Document 2 can produce rice protein that can be used as a foodstuff, but the target protein cannot be fractionated individually. In addition, the method described in Patent Document 3 is to produce protein-enriched rice flour that can be used as a foodstuff, and does not disclose any method for fractionating the target protein in the document.

  Therefore, the present invention has been made in view of the above-described conventional problems, and its purpose is to use rice, rice flour and / or rice bran as a raw material, without using reagents and chemicals that are not preferable for human consumption. Another object of the present invention is to provide a rice protein that is safely fractionated so that it can be used as a food material and a method for producing the same.

  Furthermore, the objective of this invention is providing the novel foodstuff and foodstuff or foodstuff material containing various useful substances by using the rice protein obtained by this method.

  According to the present invention, in order to achieve the above object, rice, rice flour and / or rice bran is treated with dilute acid, the resulting solution is solid-liquid separated to recover the extract, and this is salted out. A method for producing rice protein for fractionating glutelin is provided.

  Gluterin is extracted from the suspension treated with the dilute acid, and the extract collected from the suspension is salted out using, for example, sodium chloride (sodium chloride) to obtain the target glutelin under safe conditions as food.

  As the dilute acid for obtaining the extract, acids such as lactic acid, malic acid, tartaric acid, citric acid, succinic acid, adipic acid, fumaric acid, gluconic acid, phosphoric acid and other acids that are safe as foods should be used. Can do. In addition to salt (sodium chloride) described above, vinegar (acetic acid), malic acid, tartaric acid, citric acid, It is preferable to use acids such as succinic acid, adipic acid, fumaric acid, gluconic acid, phosphoric acid, and other acids that are safe as food.

  Further, according to the present invention, an enzyme solution is added to rice, rice flour and / or rice bran to react, and the resulting reaction solution is subjected to solid-liquid separation to collect a precipitate, which is solidified by sucrose density gradient centrifugation. A method for producing rice protein comprising separating a liquid, digesting a protein other than prolamin by adding a digestive enzyme to the obtained solution, separating the digested liquid into a solid and liquid, collecting a precipitate, and dialysis of this to fractionate prolamin Is provided.

  Starch and protein can be exposed by decomposing cell walls and / or cell membranes of raw rice, rice flour and rice bran with the enzyme solution. When the precipitate collected from the reaction solution is centrifuged, the starch is removed as a precipitate, and when a protein unnecessary for the digestive enzyme is digested and decomposed, the target prolamin is obtained under conditions safe as food. Pepsin can be used as such a digestive enzyme.

  According to another aspect of the present invention, a rice protein fractionated by the above-described method of the present invention and a food comprising the rice protein are provided. Since this rice protein is safe for human consumption, it can be used for food and various other purposes. For example, by deoxidizing and / or washing and dialyzing the rice protein, a product having tofu-like or yogurt-like properties can be obtained and used as it is as a food or as a part of food.

  Moreover, this rice protein can be pulverized by drying and crushing, for example, and can be used for food materials and various other uses.

  According to the present invention, a target rice protein can be selectively and highly purified from rice, rice flour and / or rice bran and extracted, and in the fractionation process, a reagent unpreferable when ingested by the human body, Since no chemicals are used, rice protein that is safe as food can be obtained. Furthermore, the rice protein obtained by this method can be used as it is or powdered to provide new foods and food materials with high nutritional value.

  Hereinafter, the present invention will be described in detail using preferred embodiments thereof. According to the method for producing rice protein of the present invention, rice storage proteins such as glutelin, prolamin, albumin and glutelin can be extracted from rice, rice flour and / or rice bran.

Glutelin fractionation method In this example, rice, rice flour and / or a method of combining extraction with dilute acid such as lactic acid and vinegar (acetic acid) and salting out with salt (sodium chloride) and vinegar (acetic acid). Fractionate glutelin from rice bran. First, lactic acid with a concentration of, for example, 1% (v / v) is added to rice flour, and the whole is well mixed and suspended with a mixer or a spatula to extract the target glutelin. The resulting suspension is subjected to solid-liquid separation by centrifugation, and the supernatant is recovered. The precipitate is again suspended with an appropriate amount of lactic acid to extract glutelin. It is preferable to repeat this extraction and supernatant collection operation at least three times. The supernatant collected in this manner is used as a glutelin extract. Since dilute acid may be used for extraction of glutelin, the concentration of lactic acid is not necessarily 1% (v / v), and vinegar can also be used.

  Saturated sodium chloride (salt) and, for example, 3% (v / v) acetic acid (vinegar) are added to the glutelin extract to salt out the glutelin. By adding acetic acid, the pH of the glutelin extract can be lowered and the salting out efficiency can be increased. Therefore, the concentration of acetic acid is not necessarily 3% (v / v), and it is sufficient if the extract can be lowered to about pH 4 or less. The precipitate obtained by this salting out contains a large amount of glutelin, which is neutralized with, for example, sodium bicarbonate (sodium bicarbonate) and dialyzed with water to obtain highly purified glutelin.

  The acid used for the extraction and salting out of glutelin is not necessarily limited to the above-mentioned lactic acid or acetic acid, but may be acids such as malic acid, tartaric acid, citric acid, succinic acid, adipic acid, fumaric acid, gluconic acid, phosphoric acid, Other acids that are safe as food can be used. Further, the neutralizing agent for neutralizing the salted out precipitate is not necessarily limited to the above-mentioned baking soda, and other alkaline agents that are safe as foods such as calcium carbonate, magnesium sulfate, and phosphates. Can be used.

Prolamin fractionation method In this example, rice, rice flour and / or rice bran were combined with a starch removal step using a buffer solution using sucrose and acetic acid and a digestion step using a digestive enzyme using an acetate buffer solution. Fractionate prolamin from First, an enzyme solution of a reaction system such as pectinase, maceroteam, cellulase, etc. is added to rice flour and allowed to react at an appropriate temperature of, for example, about 37 ° C. for a sufficient time. This reaction causes rice plant tissue to collapse and cell walls and / or cell membranes to break down, exposing starch and proteins. In addition to the enzymes described above, plant tissue degrading enzymes, cell wall degrading enzymes, and the like can be used as the enzyme solution in the reaction system.

  Next, the resulting reaction solution is subjected to solid-liquid separation by centrifugation to collect a precipitate, and further solid-liquid separated by sucrose density gradient centrifugation using an acetate buffer to precipitate starch. The remaining solution from which the precipitate has been removed contains unfractionated protein. To this, a digestive enzyme such as pepsin is added, and a protein other than the target prolamin is digested at an appropriate temperature of about 37 ° C., for example. The precipitate is collected from the digested liquid by centrifugation, neutralized with, for example, sodium bicarbonate, and then dialyzed with water to obtain highly purified prolamin.

Albumin Fractionation Method According to the present invention, albumin can be extracted by applying the same method as the aforementioned glutelin fractionation method. For albumin, the extraction condition is changed to water, and the solution is recovered by water extraction. Specifically, water is added to rice, rice flour and / or rice bran, and the whole is well mixed and suspended with a mixer or a spatula to extract the target albumin. The resulting suspension is subjected to solid-liquid separation by centrifugation, and the supernatant is recovered. The precipitate is again suspended with an appropriate amount of lactic acid, and albumin is extracted. It is preferable to repeat this extraction and supernatant collection operation at least three times. The supernatant collected in this manner is used as an albumin extract.

  Saturated sodium chloride (salt) and, for example, 3% (v / v) acetic acid (vinegar) are added to the albumin extract to salt out albumin. By adding acetic acid, the pH of the albumin extract can be lowered and the salting-out efficiency can be increased. Therefore, the concentration of acetic acid is not necessarily 3% (v / v), and it is sufficient if the extract can be lowered to about pH 4 or less. The precipitate obtained by this salting out contains a large amount of albumin, which is neutralized with, for example, sodium bicarbonate (sodium bicarbonate) and dialyzed with water to obtain highly purified albumin.

  The acid used for salting out albumin is not necessarily limited to the above-mentioned acetic acid, and is safe as acids and foods such as malic acid, tartaric acid, citric acid, succinic acid, adipic acid, fumaric acid, gluconic acid and phosphoric acid. Other acids can be used. Moreover, the neutralizing agent that neutralizes the salted out precipitate is not necessarily limited to the baking soda described above, and other alkaline agents that are safe as foods such as calcium carbonate, magnesium sulfate, and phosphates are used. Can do. In this way, albumin can be fractionated under safe conditions as food. Further, the precipitate remaining after the centrifugation at the time of recovering the albumin extract is added with a dilute acid and centrifuged as described above, whereby a solution containing glutelin is recovered.

Similarly to the method for fractionating globulin , according to the present invention, globulin can be extracted by applying the same method as the method for fractionating glutelin described above. For the globulin, the extraction condition is changed to, for example, 0.5 M sodium chloride, this is added to the precipitate of the water extraction, solid-liquid separated by centrifugation, and the solution is recovered. Specifically, for example, sodium chloride having a concentration of 0.5 M is added to rice, rice flour and / or rice bran, and the whole is well mixed and suspended with a mixer or a spatula to extract the target globulin. The resulting suspension is subjected to solid-liquid separation by centrifugation, and the supernatant is recovered. The precipitate is again suspended with an appropriate amount of 0.5 M sodium chloride, and the globulin is extracted. It is preferable to repeat this extraction and supernatant collection operation at least three times. The supernatant collected in this manner is used as a globulin extract.

  Saturated sodium chloride (salt) and, for example, 3% (v / v) acetic acid (vinegar) are added to the globulin extract to salt out the globulin. By adding acetic acid, the pH of the globulin extract can be lowered and the salting out efficiency can be increased. Therefore, the concentration of acetic acid is not necessarily 3% (v / v), and it is sufficient if the extract can be lowered to about pH 4 or less. The precipitate obtained by this salting out contains a large amount of globulin, which is neutralized with, for example, sodium bicarbonate (sodium bicarbonate) and dialyzed with water to obtain highly purified globulin.

  The acid used for salting out globulin is not necessarily limited to the above-mentioned acetic acid, and is safe as acids and foods such as malic acid, tartaric acid, citric acid, succinic acid, adipic acid, fumaric acid, gluconic acid, phosphoric acid and the like. Other acids can be used. Moreover, the neutralizing agent that neutralizes the salted out precipitate is not necessarily limited to the baking soda described above, and other alkaline agents that are safe as foods such as calcium carbonate, magnesium sulfate, and phosphates are used. Can do. In this way, globulin can be fractionated under safe conditions as food. Further, the precipitate remaining in the centrifugation when collecting the globulin extract is centrifuged by adding dilute acid as described above, whereby a solution containing glutelin is collected.

Food and Food Materials Rice protein fractionated by the above-described method is deacidified and / or washed and dialyzed by a known method to obtain a food product having tofu-like or yogurt-like physical properties. This can be provided as a tofu-like food in the form of rake tofu or rag tofu. For example, add an appropriate amount of bittern to the rice protein obtained, stir it, heat it so that it does not boil for several minutes in a microwave oven, wrap it in a cloth, etc. And harden to make a tofu-like food. Moreover, it can also provide as a new dessert made from rice by giving a preferable flavor with a suitable sweetener, jam or rice cake. In addition, it can be used as part of other foods, thereby developing new foods.

  Moreover, the rice protein fractionated by the above-described method can be pulverized by drying and crushing by a method such as freeze-drying. The dried powdered protein can be used as a material for various foods, for example, when cooking rice or adding it to confectionery materials.

Example 1
Glutelin fractionation Glutelin was purified using the fractionation method of the present invention described above. Lactic acid having a concentration of 1% (v / v) was added at a rate of 1 L to 200 g of rice flour, suspended in a mixer or a spatula so that the whole was well mixed, and glutelin was extracted. The supernatant was recovered by centrifuging the suspension, and the precipitate was suspended again with an appropriate amount of 1% (v / v) lactic acid to extract glutelin. This extraction and supernatant collection operation was repeated at least three times. Saturated sodium chloride and acetic acid having a concentration of 3% (v / v) were added to the collected supernatant as a glutelin extract to salt out glutelin. Due to the addition of acetic acid, the pH of the supernatant was changed from 5.64 before the addition to 2.17 after the addition, and a sufficient effect on protein precipitation was observed. The precipitate obtained by this salting out was neutralized with sodium bicarbonate, and then dialyzed with water to obtain purified glutelin. The purity of the obtained glutelin was 87%.

(Example 2)
Fractionation of prolamin An enzyme solution of the reaction system shown in Table 1 below was added to 200 g of rice flour and allowed to react overnight at 37 ° C. The reaction solution was centrifuged to collect a precipitate, and starch was removed by sucrose density gradient centrifugation using an acetate buffer. The remainder from which the starch was removed was digested with pepsin at 37 ° C. for 3 hours. The precipitate was recovered from the obtained digested liquid by centrifugation, neutralized with sodium bicarbonate, and dialyzed with water to obtain purified prolamin. The purity of the obtained prolamin was 80%.

  The purified glutelin and prolamin obtained in Examples 1 and 2 were analyzed for protein composition using an analyzer Agilent 2100 bioanalyzer (manufactured by Agilent Technologies Inc., USA). The electrophoresis pattern obtained as a result is shown in FIG. As shown in the figure, it is clear that the fractionated proteins in lanes 2 and 3 have the target protein separated at a higher concentration than the rice flour protein in lane 1.

(Example 3)
Trial manufacture of tofu-like food An appropriate amount of bittern was added to the rice proteins obtained in Examples 1 and 2 and stirred, and heated in a microwave oven so as not to boil for several minutes. The heated material was wrapped in a cloth placed on top of a bowl and shaped into a tofu-like food. Moreover, it poured into the container as it was, left to stand, and hardened to make a tofu-like food. The impressions of the eight panelists who tasted are that they have a little rice odor or fine odor, but they are easy to eat, white and clean, the texture is like cotton tofu or country tofu, and the taste is also delicious. Entry into the market could be expected as a new health food that has never been seen before.

Example 4
Method for using dried powdered protein The rice protein obtained in Examples 1 and 2 was dried into a powder using a freeze dryer. The taste test of cooked rice with this powder added during cooking was conducted to examine the effect of rice protein on the taste of cooked rice. The amount of rice protein added was 1% of the weight of white rice before cooking. The sensory evaluation of the taste test is based on the taste test method of the National Food Inspection Association, and relative evaluation (reference rice is 0) with respect to the reference rice (no rice protein added), and the evaluation criteria shown in Fig. 2 are set. did. Table 2 below shows the evaluation results of 31 panelists (20 men and 11 women) from the 20s to the 60s for prolamin and glutelin.

  As shown in Table 2, the rice protein dry-powdered according to the present invention is added to the rice during the cooking process to make the rice look yellow, the rice is felt hard, the sweetness is felt, etc. It is clear that it has various effects. In other words, it is possible to change the physical properties of cooked rice by taking advantage of this effect on taste. For example, rice protein-added rice is considered to be suitable for processing rice such as pilaf and fried rice because the rice becomes hard. In addition, the rice has high nutritional value because of the addition of protein, and the added value is high accordingly.

The figure which shows the electrophoresis pattern which analyzed the protein composition of glutelin and prolamin obtained in Example 1 and 2. FIG. The figure which shows the taste test evaluation criteria of the cooked rice which added the powder of the rice protein obtained in Example 1 and 2 at the time of rice cooking.

Claims (4)

  Enzyme solution is added to rice, rice flour and / or rice bran to react, and the resulting reaction solution is subjected to solid-liquid separation to collect a precipitate, followed by solid-liquid separation by sucrose density gradient centrifugation, and the resulting solution A method for producing rice protein, comprising digesting a protein other than prolamin by adding a digestive enzyme to the mixture, recovering the precipitate by solid-liquid separation, collecting the precipitate, and fractionating the prolamin by dialysis.   A rice protein produced by the method according to claim 1.   The rice protein according to claim 2, wherein the rice protein is powdered.   A food comprising the rice protein fractionated by the method according to claim 1.

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