JP2007049953A - Rice modifying agent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rice modifying agent for sustaining deliciousness of boiled rice for a long time, causing less browning and sustaining effect even when adding a sour agent. <P>SOLUTION: This rice modifying agent comprises a xylooligosaccharide composition with an average polymerization degree of 4-11 comprising a xylose polymer mixture with a polymerization degree of 2-20. The xylooligosaccharide composition has ≤40 mass% of the total content of xylooligosaccharide component with an average polymerization degree of ≤3 and xylose component. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a rice cooker. Specifically, the present invention relates to a cooked rice modifier that is added to a kettle when cooking at home, or added when cooking for business use in the restaurant industry or food manufacturing industry. In particular, the present invention relates to a rice cooker that maintains the deliciousness of cooked rice for a long period of time, has little burnt, and maintains its effect even when a sour agent is added.

Rice is a particularly important food among Japanese staple foods. Rice is usually eaten by heat gelatinization and swelling. However, Japanese people are sensitive to their preference for rice, and there are many rice dishes that are distributed without satisfying taste. Among them, cooked rice used in the food service industry, cooked rice sold at supermarkets, convenience stores, etc. are required to be modified in terms of taste.
In the above-mentioned restaurant industry, cooked rice that is distributed to supermarkets and convenience stores, etc. needs to be considered for storage stability after 24 hours. Oil is added for work efficiency such as performance. Due to these, an acid odor is generated, the original stickiness disappears, the cooked hard rice is cooked, and when stored for 24 hours, the texture deteriorates further due to the aging of starch, and improvement is expected.

As a cooked rice improver, it is required to improve texture and give it a plump feeling so that it is preferred by Japanese taste. In addition to these, improvement of workability and workability is required when cooking a large amount of rice.
The deterioration of the texture after the passage of time described above mainly depends on the aging of starch, and many documents have been disclosed so far for the purpose of preventing this aging.
Fatty acid esters (see Patent Document 1), surfactants (see Patent Document 2), partial degradation products of grain proteins (see Patent Document 3), starch degradation products (see Patent Document 4), and the like were added. However, when these additives were added, the original flavor and texture of the cooked rice were affected, and the deliciousness of the rice was made uncomfortable, so that a sufficient reforming effect could not be obtained.

In addition, the use of an enzyme such as spraying an aqueous solution containing amylase on cooked rice (see Patent Document 5) has been disclosed, but it is not always effective in terms of cost in addition to giving a sense of discomfort to the original taste of rice. Could not be a good cooked rice modifier.
Recently, a method of adding galactooligosaccharide has been proposed (see Patent Document 6). However, when galactooligosaccharide is added, the taste is poor even immediately after cooking rice, and if this is left for a long time, the taste becomes worse. Also, there are many problems with burns during cooking.
On the other hand, in order to prevent aging due to freezing of frozen cooked rice, a technique using a non-reducing or reducing oligosaccharide having a degree of polymerization of three or more sugars is disclosed (see Patent Document 7), but the taste itself of the cooked rice is improved. It is not intended to improve storage stability at room temperature.
JP-A-7-39325 JP-A-9-322725 JP-A-5-252879 JP 2004-201617 A JP 60-199355 A JP 2000-83607 A JP-A-6-141797

  The present invention is used by adding to milled rice and milled rice (1) good taste after cooking rice, and the taste is maintained even if left for a long time. (2) About cooking rice after cooking from rice cooker It is an object to provide a rice cooker that can be used together with a sour agent because it is excellent in nature and has little burnt, and (3) excellent in acid resistance.

The present invention for solving the above problems includes the following inventions (1) to (6).
(1) A rice cooker comprising a xylooligosaccharide composition having an average degree of polymerization of 4 to 11 comprising a xylose polymer mixture having a degree of polymerization of 2 to 20.

(2) The cooked rice modifier as described in the item (1), wherein the xylooligosaccharide composition has a total content of a xylooligosaccharide component having a polymerization degree of 3 or less and a xylose component of 40% by mass or less.

(3) A liquid cooked rice product obtained by filling a measuring container with a solution obtained by completely dissolving the cooked rice cooker according to (1) or (2) in water.

(4) Cooked rice prepared by adding the cooked rice modifier described in (1) or (2) above to one selected from new rice, old rice, old used rice and brown rice.

(5) Cook rice by adding the rice-rice modifier described in the above-mentioned item (1) or (2) to new rice, old rice or old-old rice to which at least one selected from wheat, straw and straw is added Cooked rice.

(6) A solution obtained by dissolving a xylooligosaccharide composition having an average degree of polymerization of 4 to 11 comprising a xylose polymer mixture having a degree of polymerization of 2 to 20 as described in the above item (1) or (2) in warm water at a high concentration. Washed rice in which the xylo-oligosaccharide is uniformly attached to the raw rice, which is sprinkled on the raw rice and dried.

  According to the present invention, by adding to cooked rice, there is provided a cooked rice modifier that has a good taste after cooking and maintains the taste even if left for a long time. According to this modifier, it is possible to improve the taste of polished rice such as new rice, old rice, and old rice, brown rice, and milled rice, and to maintain the taste immediately after cooking for a long time. Therefore, it is also suitable for use in cooked rice used in the food service industry or sold in convenience stores. In addition, cooked rice is excellent in separation from the rice cooker and has little burnt, so it has a good yield and is suitable for mass production in food factories. And it is excellent in acid resistance, can provide the modifier for cooked rice which can be used with a sour agent, and furthermore, since it is stable against stomach acid, the intestinal action of oligosaccharide can be expected.

Hereinafter, the xylo-oligosaccharide composition which is an essential component in the rice cooker of the present invention will be described.
The xylooligosaccharide composition used in the present invention is a xylooligosaccharide composition having a polymerization degree of 2 to 20 and an average polymerization degree of 4 to 11. This is a mixture of xylooligosaccharides containing a large amount of pentamer to decamer having a large molecular weight. This xylooligosaccharide composition has a total content of xylooligosaccharide components and xylose components of trimer or less of 40% by mass or less, preferably 30% by mass or less, and an average degree of polymerization of 4 or more, preferably 5 or more. A mixture of xylooligosaccharides that is less than 11.

A xylo-oligosaccharide having an average degree of polymerization of less than 4 is weak in effect as a rice cooker of the invention, and easily undergoes Maillard reaction at the time of rice cooking, or browning becomes easier. When a xylo-oligosaccharide having an average degree of polymerization exceeding 11 is used, the solubility in water becomes extremely low, it becomes difficult to uniformly contact all rice grains, and the viscosity of the aqueous solution increases, making it unsuitable for use. .
In the present invention, as the xylooligosaccharide, a xylooligosaccharide in which uronic acid is bonded to the side chain of xylose can also be used. Uronic acid may be an acidic type or a salt type substituted with calcium, magnesium, sodium, or potassium.

  The xylo-oligosaccharides used as the xylo-oligosaccharide composition as described above are obtained by using wood, especially kraft-distilled wood pulp, as a raw material, and treating the hemicellulose therein enzymatically or physicochemically. The xylo-oligosaccharide thus obtained may be obtained as a mixture having an average degree of polymerization of 4 to 11 depending on the kind of raw pulp, the place of production, cooking conditions or acid hydrolysis conditions, etc. May be obtained as a mixture of less than 4. In the case where the average degree of polymerization is less than 4, the sugar solution after the acid hydrolysis treatment is filtered with a membrane treatment (such as an RO membrane used for filtration of an enzyme treatment solution in Examples described later). To remove xylose, xylobiose and the like to prepare a mixture having an average degree of polymerization of 4 to 11. The removal of low-molecular components such as unpolymerized xylose and xylobiose by the RO membrane can be performed by changing the salt blocking rate of the RO membrane to control the molecular weight permeating the membrane.

In particular, a xylo-oligosaccharide composition having an average degree of polymerization of about 4 to 11 obtained by acid hydrolysis of a sugar solution containing “composite of xylo-oligo and lignin” obtained by enzymatic treatment of kraft-cooked wood pulp is preferable. . According to this method, since the xylo-oligosaccharide having a distribution in the degree of polymerization and an average high degree of polymerization can be obtained, the effect of the present invention as a xylo-oligosaccharide composition is easily exhibited even if it is used as it is.
The “average degree of polymerization” is a value obtained by dividing the total amount of saccharides by the amount of reducing sugars, as will be described in Examples below.

The rice cooker of the present invention can be used for reforming rice such as milled rice containing wheat, rice bran, rice bran, etc. in addition to polished rice such as new rice, old rice, and old rice, and brown rice. As rice, in addition to normal Japanese type (Japonica) rice, it can be applied to rice with long grain and low stickiness like Indian type (Indica) rice.
In particular, old rice and old rice are suitable as targets for the cooked rice modifier of the present invention because the taste is deteriorated and the taste is greatly reduced after cooking. When the rice cooker of the present invention is applied to used rice and used rice, the taste is remarkably improved.
In addition, about 10% of cereal grains may be added to the cooked rice for health maintenance. At this time, a decrease in taste becomes a problem, but the cooked rice modifier of the present invention can reduce the decrease in taste.

  In the use of the cooked rice modifier of the present invention, the amount of xylo-oligosaccharide added is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of raw rice. When the amount is less than 0.1 parts by mass, the effect of addition is small, and when the amount exceeds 10 parts by mass, the taste of cooked rice after cooking is changed, and the sweetness of the oligosaccharide is felt. Preferably, it is 0.5-3 mass parts.

  The method for adding the cooked rice modifier of the present invention includes a method of adding the xylo-oligosaccharide of the present invention to the washed rice and then adding the cooked water and a method of adding the xylo-oligosaccharide by dissolving it in the brewed cooking water in advance. . In any case, in order to effectively function as a rice cooker, it is preferable to uniformly dissolve in cooking water to prevent uneven cooking. This point will be described in detail below.

According to the study by the present inventors, xylo-oligosaccharides currently marketed have an average degree of polymerization of 3 or less, mainly composed of xylobiose and xylotriose. Since this product has a low degree of polymerization, it is highly soluble in water. Therefore, if it is sprinkled on fresh rice in a kettle and then added and stirred, it will dissolve almost uniformly.
On the other hand, when it becomes a xylooligosaccharide mixed composition having an average degree of polymerization of 4 or more, components having a degree of polymerization of 10 or more are also present. Those having a polymerization degree of 10 or more are not easily dissolved in water at room temperature, and are dissolved for a while if dissolved at about 80 ° C., but have a property of being precipitated when time passes after being cooled. It was found that when such rice was sprinkled with raw rice and sprinkled with raw rice, it was not evenly distributed throughout, but “cooking unevenness” that could be seen visually appeared.
Since those having a polymerization degree of 3 or less are sweet, it is presumed that they have not been studied as a taste improver for cooked rice. Further, it is presumed that xylo-oligosaccharide having a high degree of polymerization has not been studied as a rice cooker because of its difficulty in solubility as described above.

The inventors of the present invention, even with a xylo-oligosaccharide composition containing an oligosaccharide having a polymerization degree of 10 or more, heat and dissolve an undissolved portion, cool it, mix it with fresh rice before forming a precipitate, and cook rice. As a result of discovering that it can be cooked without “cooking unevenness” and conducting taste research, the present invention has been achieved.
Of course, other than this method, the effect of the present invention can be exhibited if the xylo-oligosaccharide component is uniformly distributed in the cooked rice. As an example of such a method, (1) it is formed into a fine granular material to be a rice cooker. (2) It is dissolved in warm water, cooled and filled into a bottle for liquid rice. (3) What was dissolved in high concentration of xylo-oligosaccharides in warm water was sprinkled on the raw rice and dried, and “washed rice” (non-washed rice) with the xylo-oligosaccharide components uniformly attached to the raw rice And so on).

  Examples of rice cooking methods include a gas kettle, an electric kettle, and a method of cooking rice by pressurizing steam in a container, and the present invention can cope with any of these methods. Furthermore, it is not limited by the capacity of the cooked rice.

  The cooked rice reforming agent of the present invention is not particularly limited, but the cooked rice reforming effect possessed by xylooligosaccharides is exhibited even when used in combination with other ingredients that have a cooked rice reforming effect. In particular, the cooked rice modifier of the present invention can be used together with a sour agent. Since the sour agent has an effect of suppressing the growth of microorganisms, it is added to cooked rice generally distributed as a lunch box. Examples of acidulants include acetic acid, citric acid, fumaric acid, gluconic acid, protamine, glycine and the like.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited thereto. In each example and comparative example, polished rice was used as a food material.

Production Example 1 (Production of Xylooligosaccharide NX5)
Using unmixed hardwood chips consisting of 70% by mass of domestic hardwood chips and 30% by mass of eucalyptus wood as raw materials, unbleached pulp manufactured by a factory with a kappa value of 20.1 and a pulp viscosity of 41 cps was obtained. Subsequently, oxygen delignification was performed to obtain an oxygen delignification pulp having a copper number of 9.6 and a pulp viscosity of 25.1 mPa · s. After washing the pulp, the pulp concentration is adjusted to 10%, diluted sulfuric acid is added to adjust the pH to 8, and then the Bacillus sp. S-2113 strain (incorporated administrative agency, National Institute of Advanced Industrial Science and Technology, Depositary Strain FERM BP) -5264) produced xylanase was added to 1 unit / g of pulp and treated at 60 ° C. for 120 minutes. After the treatment, it was filtered through a 100 mesh filter cloth to separate pulp residues and the like, and a 1050 liter treatment liquid (3900 g as the total sugar amount) containing a total sugar concentration of 3700 mg / l was obtained. Subsequently, the mixture was concentrated 40 times by volume using an NF membrane (Nitto Denko: NTR-7450, membrane quality: sulfonated polyethersulfone, salt rejection 50%). This concentrated solution had a total sugar amount of 2700 g, and the total sugar recovery rate was 70%.

  To 1,000 ml of the concentrated sugar solution obtained above, sulfuric acid was added to adjust the pH to 3.5, and then this concentrated sugar solution was reacted at 121 ° C. for 1 hour. As a result of analyzing the reaction product by ion chromatography using an ion chromatography column (Dionex: PA-10), the polymerization degree distribution as shown in Table 1 (in Table 1, X1 to X13 are the polymerization degree of xylose). Of xylo-oligosaccharides (mainly dimers to 10-mers).

  A sugar solution (117 mg / ml) of a xylo-oligosaccharide mixture prepared in the acid hydrolysis treatment step, 1.2 g as a total sugar amount, was charged with a strongly acidic ion exchange resin (Rohm and Haas: Amberlite 200C). The column (inner diameter 36 mm, length 150 mm) was loaded. After collecting the xylo-oligosaccharide that passed through the column, it was loaded onto a similar column packed with a weakly basic ion exchange resin (Rohm and Haas: IRA67). After concentration, the xylo-oligosaccharide obtained through the column was decolorized by adding 80 mg of activated carbon (manufactured by Wako Pure Chemicals: product number 037-02115) to the xylo-oligosaccharide solution and stirring at 60 ° C. for 1 hour. After stirring, the activated carbon was filtered through a 0.22 μm membrane filter to obtain a purified xylooligosaccharide solution. The average degree of polymerization of the purified xylo-oligosaccharide was measured by the following method, and the result was 5.0. In addition, those having a polymerization degree of 3 or less are about 25.4% by mass, those having a polymerization degree of 4 to 11 are about 74.6% by mass in total, and those having a polymerization degree of 12 or more are also present. The amount was not quantifiable accurately. The xylooligosaccharide obtained here is referred to as NX5.

<Measurement method>
(1) Quantification method of total sugar amount: The total sugar amount was determined by preparing a calibration curve using D-xylose (Wako Pure Chemical Industries, Ltd.) and quantifying it with the phenol-sulfuric acid method (quantitative method for reducing sugar; Academic Publishing Center). .
(2) Method for quantifying reducing sugar amount: The amount of reducing sugar is prepared by using D-xylose (Wako Pure Chemical Industries) as a calibration curve, and quantified by the Sommoji-Nelson method (quantifying method for reducing sugar; Society of Science Publishing Center). did.
(3) Determining the average degree of polymerization: Keeping the sample sugar solution at 50 ° C., centrifuging at 15000 rpm for 15 minutes to remove insoluble matter, and dividing the total sugar amount in the supernatant by the reducing sugar amount (both converted to xylose) The average degree of polymerization was determined.

<Example 1>
An experiment was conducted using 2002 Koshihikari (old and old rice). The xylo-oligosaccharide NX5, which is the cooked rice modifier of the present invention produced in Production Example 1, was dissolved in water and added to a ratio of 1 g per 100 g of raw rice. The amount of water added is 145 g of water for 100 g of raw rice.
NX5 may remain slightly insoluble in water, but it is completely dissolved by heating water, heating to about 70 ° C and stirring, and even after cooling to 40 ° C, the dissolved state remains. I kept it.
It was soaked for 30 minutes, cooked with a rice cooker, steamed for 15 minutes, and then cooled with a blower for 20 minutes. After cooling, the taste value was measured with a rice cooking taste meter (STA-1A) manufactured by Satake Corporation (30 minutes after the end of steaming). In order to see the change over time, the measurement was performed after 24 hours and 48 hours. The results are shown in Table 2.
After the completion of rice cooking, the degree of scorching inside the rice cooker was visually evaluated. The results are shown in Table 3.

<Comparative Example 1>
The taste value was measured in the same manner as in Example 1 except that galactooligosaccharide [Nisshin Sugar Co., Ltd. “Cup Oligosaccharide H-70”, degree of polymerization of about 3] was used as a rice cooker. . In addition, after completion | finish of rice cooking, the degree of the burning inside a rice cooker was visually evaluated. The results are shown in Tables 2 and 3.

<Comparative example 2>
The taste value was measured in the same manner as in Example 1 except that the cooked rice modifier was not used. In addition, after completion | finish of rice cooking, the degree of the burning inside a rice cooker was visually evaluated. The results are shown in Tables 2 and 3.

<Comparative Example 3>
The taste value was measured in the same manner as in Example 1 except that xylooligosaccharide (manufactured by Suntory Ltd.) trade name “xylooligosaccharide” average degree of polymerization of 3 or less] was used as the modifier for cooked rice. In addition, after completion | finish of rice cooking, the degree of the burning inside a rice cooker was visually evaluated. The results are shown in Tables 2 and 3.

<Method for measuring the taste value of cooked rice>
Principle of cooked rice taste meter (STA-1A) manufactured by Satake Corporation:
The deliciousness of rice is determined by the rate of gelatinization (α conversion) of rice starch. The principle of the rice cooking taste meter calculates the taste value by measuring the ratio of gelatinization degree with a sensor using reflected light and transmitted light with a near infrared ray.
When quantifying, a calibration curve created from multiple regression analysis using 90 samples whose appearance, fragrance, stickiness, hardness and comprehensive evaluation were found from sensory test evaluation values issued by the Japan Grain Test Association. Based on this, the measured sample is digitized.

○ There was no burning in the rice cooker and rice.
Δ: There was no burning in the rice cooker, but the rice was burnt.
X The rice cooker was burnt and rice was burnt.

  From the results shown in Table 2, as a result of measurement by a taste meter, the decrease in taste value is moderate in xylo-oligosaccharide and the taste is maintained. Here, when the measured value is 5 or more away, a clear difference in taste is felt when eating. Forty-eight hours after cooking, by adding the xylooligosaccharide, which is a rice cooker of the present invention, the taste is maintained as compared with Comparative Examples 1 and 2.

  From the results in Table 3, it can be seen that the addition of xylo-oligosaccharide, which is a rice cooker according to the present invention, is easy to remove from the kettle, and the cooked rice is also in a state where each grain is well loosened. On the other hand, when galactooligosaccharide was added, the rice was cooked. When the rice cooker was not added, both the bottom of the rice cooker and the cooked rice were recognized. From this, it can be seen that, by adding xylo-oligosaccharide, when cooking a large amount of rice, it is possible to provide cooked rice with good yield that is easy to leave the kettle and does not burn to the kettle.

<Example 2>
1 g of xylooligosaccharide produced in Production Example 1 was dissolved in 100 ml of 100 mM acetate buffer (pH 4.0) or 100 ml of phosphate buffer (pH 6.0). A pressure heat treatment was performed at 105 ° C. for 5 minutes. The oligosaccharide degradation before and after the heat treatment was measured, and the results are shown in Table 4.

<Comparative example 4>
Experiments were carried out in the same manner as in Example 2 using 1 g of fructooligosaccharide (Mayoligo P: Meiji Seika degree of polymerization of about 3) instead of xylooligosaccharide. The results are shown in Table 4.
<Analysis of sugar>
Various oligosaccharides were analyzed by ion chromatography using an ion chromatography column (Dionex: PA-10).
The analysis conditions of the sample were analyzed using the following liquid A and liquid B.
Solution A: 100 mM NaOH solution Solution B: Eluent containing 500 mM sodium acetate in 100 mM NaOH solution

  The analyzer used was DX-500 (Dionex). The sample concentration was provided by diluting with pure water so that the total sugar concentration was 0.05%. 25 ul of sample was introduced into the PA-10 column equilibrated with the liquid A, and the analysis was started. The gradient with the liquid B was started 5 minutes after the start of the analysis, and the ratio of the liquid B reached 60% 30 minutes after the start of the analysis. Thus, the composition of the separation solution was changed. The flow rate was unified at 1 ml / min throughout the analysis. Fructooligosaccharides decomposed 14% when heated at pH 6.0. Furthermore, when fructooligosaccharide was heated at pH 4.0, 63% was lost due to decomposition and converted to fructose and sucrose. On the other hand, xylo-oligosaccharides decomposed only 0.3% at pH 4.0. Similarly, xylo-oligosaccharides decomposed only 0.2% when heated at pH 6.0. This proved that xylo-oligosaccharides have higher heat resistance and acid resistance than fructooligosaccharides. This is shown in Table 4.

  From Table 4, it can be seen that the xylo-oligosaccharide which is the rice cooker of the present invention is stable even in a low pH range.

In the restaurant industry, convenience stores, etc., it is common to lower the pH to around 4.0 with acidulants such as gluconic acid. The xylo-oligosaccharide, which is a rice cooker of the present invention, is stable even at a low pH, so that it can be used in such applications.
In addition, xylooligosaccharide is expected to have an intestinal effect when eaten, but stability to gastric acid is expected. Therefore, the rice cooker of the present invention is expected to have an intestinal function.

Claims (6)

  A rice cooker comprising a xylooligosaccharide composition having an average degree of polymerization of 4 to 11 comprising a xylose polymer mixture having a degree of polymerization of 2 to 20.   The modifier for cooked rice according to claim 1, wherein the xylooligosaccharide composition has a total content of a xylooligosaccharide component having a degree of polymerization of 3 or less and a xylose component of 40% by mass or less.   A liquid cooked rice product obtained by filling a measuring container with a solution prepared by completely dissolving the cooked rice cooker according to claim 1 or 2 in water.   Cooked rice prepared by adding the rice rice modifier according to claim 1 or 2 to one selected from new rice, old rice, old used rice and brown rice. Cooked rice prepared by adding the cooked rice modifier according to claim 1 or 2 to old rice to which at least one selected from wheat, straw and straw is added, or used rice.   A solution obtained by dissolving a xylooligosaccharide composition having an average degree of polymerization of 4 to 11 and comprising a xylose polymer mixture having a degree of polymerization of 2 to 20 according to claim 1 or 2 in warm water at a high concentration is sprinkled on rice and dried. Washed rice in which the xylo-oligosaccharide composition is uniformly attached to fresh rice.