Rice flour noodle and producing method of rice flour noodle

Abstract

To provide rice flour noodle which is easy to handle during production, has high moldability and shape retention of a noodle shape, and has good taste which maintains texture peculiar to rice flour even when a blending amount of starches is small.SOLUTION: Rice flour noodle contains 0.1 to 10 parts by mass of carboxymethylated cellulose and its salt based on 100 parts by mass of grain flour with rice flour as a main component.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to rice flour noodles containing carboxymethyl cellulose and a method for producing the same. [Background technology]

[0002] In recent years, the use of rice flour has been expected due to the problem of wheat allergies and concerns about the global wheat supply. However, rice flour does not contain gluten like wheat flour, and therefore lacks adhesive power. Even when made into noodles in the same way as when wheat flour is used as the raw material, the dough does not stick well and it is difficult to form into noodle strands.

[0003] For this reason, noodle-making methods that add starches have been proposed. For example, in Patent Document 1, 80% by weight of rice flour is mixed with 20% by weight of starch, but because the amount of starch mixed is too high, there is concern that the transparent appearance and good texture with chewy viscoelasticity and little stickiness that are characteristic of rice flour may be lost. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2002-315526 A Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, an objective of the present invention is to provide rice flour noodles that are easy to handle during production, have high formability and shape retention, and have a good taste that maintains the texture unique to rice flour, even when the blended amount of starches is small, and to provide a production method thereof. [Means for solving the problem]

[0006] As a result of intensive research, the present inventors have found that the problems can be solved as follows. (1) Rice flour noodles, characterized by containing 0.1 to 10 parts by mass of carboxymethyl cellulose and its salts per 100 parts by mass of cereal flour mainly composed of rice flour. (2) The rice flour noodles according to (1), wherein the carboxymethyl cellulose and salts thereof have a degree of carboxymethyl substitution of 0.01 or more and 0.50 or less. (3) The rice flour noodles according to (1), characterized in that the carboxymethyl cellulose and its salt are contained in an amount of 0.1 to 5 parts by mass per 100 parts by mass of cereal flour mainly composed of rice flour. (4) A method for producing rice flour noodles, comprising the steps of: preparing a rice flour composition containing 0.1 to 10 parts by mass of carboxymethyl cellulose and a salt thereof per 100 parts by mass of grain flour having rice flour as a main component; adding 30 to 100 parts by mass of water per 100 parts by mass of the grain flour to the rice flour composition, and kneading the mixture to obtain a rice flour dough; and forming the rice flour dough into noodles. Effect of the Invention

[0007] Effects of the Invention According to the present invention, it is possible to provide rice flour noodles that are easy to handle during production, have high formability and shape retention, and have good flavor while maintaining the texture unique to rice flour, even when the blended amount of starches is small, and a production method thereof. [Brief description of the drawings]

[0008] [Figure 1] Photographs showing the appearance of cooked rice flour noodles of Example 1, Example 2, Comparative Example 1, Comparative Example 2, and a control. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The present invention will be described in detail below, but unless otherwise specified, the expression "AA to BB%" means "not less than AA% and not more than BB%".

[0010] (Rice noodles) The rice flour noodles of the present invention contain 0.1 to 10 parts by mass, preferably 0.1 to 5 parts by mass, and more preferably 0.5 to 3 parts by mass of carboxymethyl cellulose and its salts per 100 parts by mass of cereal flour whose main component is rice flour. Having the amount of carboxymethyl cellulose and its salts in the above ranges results in favorable workability and texture. If the amount is more than the above upper limit, there is a risk that the dough will become sticky, resulting in a poor texture and adhesion to the container, and if the amount is less than the above lower limit, there is a risk that the formability and shape retention of the noodle shape will decrease.

[0011] (Flours with rice flour as the main ingredient) The flours containing rice flour as a main component used in the present invention refer to flours containing rice flour at a ratio of more than 50% by mass. From the viewpoint of maintaining the chewy texture characteristic of rice flour, the flours of the present invention preferably contain rice flour at a ratio of 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more, and all of the flours may be rice flour. If the rice flour content is too low, the texture and taste characteristic of rice flour may be lost.

[0012] The rice flour used in the present invention can be any rice flour available on the market that can be used for food products, without any particular limitations. For example, rice flour obtained by grinding polished rice that is generally used for food purposes can be used.

[0013] Examples of flours other than rice flour that can be used in the present invention include wheat flour, buckwheat flour, barley flour, and starches such as tapioca starch, potato starch, and corn starch. Examples of starches include unprocessed starch and processed starch obtained by subjecting unprocessed starch to processing (e.g., etherification, esterification, acetylation, gelatinization, cross-linking, etc.). One type of flour other than rice flour may be used alone, or two or more types may be used in combination.

[0014] (Carboxymethyl cellulose and its salts) Carboxymethylated cellulose has a structure in which some of the hydroxyl groups in the glucose residues constituting cellulose are ether-bonded to carboxymethyl groups. Carboxymethylated cellulose may take the form of a salt. Examples of the salt of carboxymethylated cellulose include metal salts such as sodium carboxymethylated cellulose.

[0015] (Degree of carboxymethyl substitution) The carboxymethylated cellulose and salts thereof (hereinafter also referred to as "CMC") used in the present invention preferably have a carboxymethyl substituent per glucose unit (hereinafter also referred to as "degree of substitution") of 0.01 or more and 0.5 or less, more preferably 0.05 or more and 0.45 or less, and even more preferably 0.1 or more and 0.4 or less. Having a degree of substitution of CMC within this range results in excellent workability when producing rice flour noodles, excellent moldability and shape retention of the rice flour noodles, and excellent texture and taste of the rice flour noodles after boiling. Note that if the degree of substitution of CMC is low, such as less than 0.01, the hydrophilicity of CMC decreases, and therefore it is not suitable because it has poor water retention when added to rice flour noodles.

[0016] (Crystallization degree of cellulose type I) The crystallinity of cellulose type I in the carboxymethylated cellulose used in the present invention is not particularly limited. The crystallinity of cellulose can be controlled by the concentration of the mercerizing agent, the temperature during treatment, and the degree of carboxymethylation. Since a high concentration of alkali is used in mercerization and carboxymethylation, the cellulose type I crystals are easily converted to type II crystals, but the desired crystallinity can be maintained by adjusting the degree of modification, such as by adjusting the amount of alkali (mercerizing agent) used. The lower limit of the crystallinity of cellulose type I in the carboxymethylated cellulose used in the present invention is 0. The upper limit is not particularly limited. In reality, the upper limit is considered to be about 90%.

[0017] The method for measuring the crystallinity of cellulose type I of carboxymethyl cellulose is as follows: The sample is placed in a glass cell and measured using an X-ray diffraction measuring device (LabX XRD-6000, manufactured by Shimadzu Corporation). The degree of crystallinity is calculated using the method of Segal et al. The diffraction intensity at 2θ = 10° to 30° in the X-ray diffraction diagram is used as the baseline, and the degree of crystallinity is calculated from the diffraction intensity of the 002 plane at 2θ = 22.6° and the diffraction intensity of the amorphous part at 2θ = 18.5° using the following formula: Xc = (I002c - Ia) / I002c × 100 Xc = Crystallinity of cellulose type I (%) I002c: 2θ=22.6°, diffraction intensity of 002 plane Ia: 2θ=18.5°, diffraction intensity of the amorphous part.

[0018] (viscosity) The viscosity of the carboxymethylated cellulose used in the present invention is not particularly limited, but from the viewpoint of preferable workability and moldability, the B-type viscosity (conditions: rotation speed 30 rpm, temperature 25°C) when made into an aqueous dispersion with a solid content of 1% by mass is preferably 1 to 400 mPa s, more preferably 5 to 300 mPa s, and even more preferably 10 to 200 mPa s. If the B-type viscosity is too higher than the above upper limit, the rice flour dough may become sticky, and if it is too lower than the above lower limit, the moldability may decrease.

[0019] (Average particle size) In the present invention, the carboxymethylcellulose blended into the rice flour noodles is preferably in powder or fine powder form, and the average particle size under conditions of a moisture content of less than 10% by mass is preferably less than 70 μm, more preferably 10 μm or more and less than 65 μm, and even more preferably 15 μm or more and less than 60 μm. It is presumed that by having the average particle size within the above range, the fiber length and fiber diameter of the carboxymethylcellulose are not too thin and are kept within a certain range, making it easier to exhibit thickening properties (gelation) while maintaining good dispersibility. If the average particle size is too large above the upper limit, there is a risk of the texture being deteriorated, and if it is too small below the lower limit, the powder is likely to fly up and become difficult to handle.

[0020] The average particle size in the present invention is the particle size that includes 50% of the particles when calculated from the minimum value in the volume-based particle size distribution. The particle size distribution can be measured using a laser diffraction / scattering particle size distribution analyzer.

[0021] (Production method of carboxymethyl cellulose) Carboxymethylated cellulose can generally be produced by treating cellulose with an alkali (mercerization), and then reacting the resulting mercerized cellulose (also called alkali cellulose) with a carboxymethylating agent (also called etherifying agent). Common methods for producing carboxymethylated cellulose include the aqueous method, in which both mercerization and carboxymethylation are carried out using water as a solvent, and the solvent method, in which both mercerization and carboxymethylation are carried out in a solvent mainly composed of an organic solvent. From the viewpoint of the degree of carboxymethyl substitution and the degree of crystallinity, the carboxymethylated cellulose used in the present invention is preferably produced, for example, by carrying out mercerization in a solvent mainly composed of water or in a mixed solvent of water and an organic solvent, and then carrying out carboxymethylation in a mixed solvent of water and an organic solvent.

[0022] (cellulose) In this specification, cellulose refers to a polysaccharide having a structure in which D-glucopyranose (also simply called "glucose residue" or "anhydroglucose") is linked together through β-1,4 bonds. Cellulose is generally classified into native cellulose, regenerated cellulose, fine cellulose, microcrystalline cellulose in which the amorphous region is removed, etc., based on the origin, production method, etc. In the present invention, any of these celluloses can be used as the raw material for mercerized cellulose.

[0023] Examples of natural cellulose include bleached pulp or unbleached pulp (bleached wood pulp or unbleached wood pulp), linters, refined linters, and cellulose produced by microorganisms such as acetic acid bacteria. The raw material for bleached pulp or unbleached pulp is not particularly limited, and examples thereof include wood, cotton, straw, bamboo, hemp, jute, kenaf, etc. The method for producing bleached pulp or unbleached pulp is also not particularly limited, and may be a mechanical method, a chemical method, or a method that is an intermediate combination of the two. Examples of bleached or unbleached pulp classified according to the production method include mechanical pulp (thermomechanical pulp (TMP), groundwood pulp), chemical pulp (sulfite pulp such as softwood unbleached sulfite pulp (NUSP) and softwood bleached sulfite pulp (NBSP), and kraft pulp such as softwood unbleached kraft pulp (NUKP), softwood bleached kraft pulp (NBKP), hardwood unbleached kraft pulp (LUKP), and hardwood bleached kraft pulp (LBKP)). Furthermore, in addition to papermaking pulp, dissolving pulp may be used. Dissolving pulp is chemically refined pulp that is mainly used by dissolving it in chemicals, and is the main raw material for artificial fibers, cellophane, etc.

[0024] Examples of regenerated cellulose include cellulose dissolved in some solvent such as cuprammonium solution, cellulose xanthate solution, morpholine derivative, etc., and spun again. Examples of fine cellulose include those obtained by depolymerizing the above-mentioned natural cellulose and regenerated cellulose and other cellulose-based materials (e.g., acid hydrolysis, alkali hydrolysis, enzymatic decomposition, explosive crushing, vibration ball mill treatment, etc.), and those obtained by mechanically treating the above-mentioned cellulose-based materials.

[0025] (Mercerization) Mercerized cellulose (also called alkali cellulose) is obtained by adding a mercerizing agent (alkali) to the above-mentioned cellulose as a raw material. By adjusting the composition of the solvent in the mercerization reaction and the composition of the solvent in the carboxymethylation reaction, it is possible to economically obtain carboxymethylated cellulose that has both a specific degree of carboxymethyl substitution and the crystallinity of cellulose type I.

[0026] For example, by using water as the main solvent in the mercerization reaction and using a mixed solvent of an organic solvent and water in the subsequent carboxymethylation, it is possible to obtain carboxymethylated cellulose having a specific degree of carboxymethyl substitution and a crystallinity of 50% or more of cellulose type I. The term "water-based solvent" refers to a solvent containing water at a ratio of more than 50% by mass. The water content in the water-based solvent is preferably 55% by mass or more, more preferably 60% by mass or more, more preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more. Particularly preferably, the water-based solvent is 100% by mass (i.e., water). The higher the water content during mercerization, the more advantageously carboxymethyl groups are introduced into cellulose more uniformly. Examples of solvents other than water (used mixed with water) in the water-based solvent include organic solvents used as a solvent during the subsequent carboxymethylation. Examples of such solvents include alcohols such as methanol, ethanol, N-propyl alcohol, isopropyl alcohol, N-butanol, isobutanol, and tertiary butanol, ketones such as acetone, diethyl ketone, and methyl ethyl ketone, as well as dioxane, diethyl ether, benzene, and dichloromethane, and these can be added alone or in a mixture of two or more kinds to water in an amount of less than 50% by mass to be used as a solvent for mercerization. The organic solvent in the solvent mainly composed of water is preferably 45% by mass or less, more preferably 40% by mass or less, more preferably 30% by mass or less, more preferably 20% by mass or less, more preferably 10% by mass or less, more preferably 5% by mass or less, and more preferably 0% by mass.

[0027] Examples of the mercerizing agent include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide, and any one or more of these can be used in combination. The mercerizing agent is not limited to these, but these alkali metal hydroxides can be added to the reactor as an aqueous solution of, for example, 1 to 60 mass %, preferably 2 to 45 mass %, and more preferably 3 to 25 mass %.

[0028] The amount of the mercerizing agent used is not particularly limited, but is preferably an amount that allows the degree of carboxymethyl substitution in the carboxymethyl cellulose to be 0.20 or more. In one embodiment, the amount is preferably 0.1 mol or more and 2.5 mol or less, more preferably 0.3 mol or more and 2.0 mol or less, and even more preferably 0.4 mol or more and 1.5 mol or less, per 100 g (bone dry) of cellulose.

[0029] The amount of the solvent during mercerization is not particularly limited as long as it allows stirring and mixing of the raw materials, but is preferably 1.5 to 20 times, and more preferably 2 to 10 times, the mass of the cellulose raw material.

[0030] The mercerization treatment is carried out by mixing the raw material (cellulose) with a solvent, adjusting the temperature of the reactor to 0 to 70°C, preferably 10 to 60°C, more preferably 10 to 40°C, adding an aqueous solution of a mercerizing agent, and stirring for 15 minutes to 8 hours, preferably 30 minutes to 7 hours, more preferably 30 minutes to 3 hours, to obtain mercerized cellulose (alkali cellulose).

[0031] The pH during mercerization is preferably 9 or more, which allows the mercerization reaction to proceed. The pH is more preferably 11 or more, further preferably 12 or more, and may be 13 or more. There is no particular upper limit to the pH.

[0032] The mercerization can be carried out using a reactor capable of mixing and stirring the above-mentioned components while controlling the temperature, and various reactors conventionally used for mercerization reactions can be used. For example, a batch-type stirring device having two shafts for stirring and mixing the above-mentioned components is preferred from the viewpoints of both uniform mixing ability and productivity.

[0033] (Carboxymethylation) Carboxymethylated cellulose is obtained by adding a carboxymethylating agent (also called an etherifying agent) to mercerized cellulose.

[0034] Examples of the carboxymethylating agent include monochloroacetic acid, sodium monochloroacetate, methyl monochloroacetate, ethyl monochloroacetate, isopropyl monochloroacetate, etc. Among these, monochloroacetic acid or sodium monochloroacetate is preferred in terms of availability of the raw material.

[0035] The amount of the carboxymethylating agent used is not particularly limited, but in one embodiment, from the viewpoint of effective utilization, it is preferable to add in the range of 0.5 to 1.5 mol per anhydrous glucose unit of cellulose. The lower limit of the above range is more preferably 0.6 mol or more, even more preferably 0.7 mol or more, and the upper limit is more preferably 1.3 mol or less, even more preferably 1.1 mol or less. The carboxymethylating agent can be added to the reactor as, for example, a 5 to 80 mass % aqueous solution, more preferably 30 to 60 mass %, but is not limited thereto, or can be added in a powder state without dissolving.

[0036] The molar ratio of the mercerizing agent to the carboxymethylating agent (mercerizing agent / carboxymethylating agent) is generally 0.90 to 2.45 when monochloroacetic acid or sodium monochloroacetate is used as the carboxymethylating agent. The reason is that if it is less than 0.90, the carboxymethylation reaction may be insufficient, and unreacted monochloroacetic acid or sodium monochloroacetate may remain and be wasted, and if it exceeds 2.45, a side reaction between the excess mercerizing agent and monochloroacetic acid or sodium monochloroacetate may proceed, resulting in the production of an alkali metal glycolate, which may be uneconomical.

[0037] The concentration of the cellulose raw material in the carboxymethylation reaction is not particularly limited, but is preferably 1 to 40% (w / v) from the viewpoint of increasing the effective utilization rate of the carboxymethylating agent. The effective utilization rate of the carboxymethylating agent refers to the ratio of the carboxymethyl groups introduced into cellulose among the carboxymethyl groups in the carboxymethylating agent.

[0038] Simultaneously with the addition of the carboxymethylating agent, or before or immediately after the addition of the carboxymethylating agent, an organic solvent or an aqueous solution of an organic solvent is appropriately added to the reactor, or the organic solvent other than water used in the mercerization treatment is appropriately reduced by reducing pressure or the like to form a mixed solvent of water and an organic solvent, and the carboxymethylation reaction is allowed to proceed in this mixed solvent of water and an organic solvent. The timing of the addition or reduction of the organic solvent may be any time between the end of the mercerization reaction and immediately after the addition of the carboxymethylating agent, and is not particularly limited, but is preferably within 30 minutes before or after the addition of the carboxymethylating agent, for example.

[0039] Examples of the organic solvent include alcohols such as methanol, ethanol, N-propyl alcohol, isopropyl alcohol, N-butanol, isobutanol, and tertiary butanol, ketones such as acetone, diethyl ketone, and methyl ethyl ketone, as well as dioxane, diethyl ether, benzene, and dichloromethane, and these can be used alone or in a mixture of two or more kinds as a solvent for carboxymethylation by adding them to water. Among these, monohydric alcohols having 1 to 4 carbon atoms are preferred because of their excellent compatibility with water, and monohydric alcohols having 1 to 3 carbon atoms are more preferred.

[0040] The ratio of the organic solvent in the mixed solvent during carboxymethylation is preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 40% by mass or more, even more preferably 45% by mass or more, and particularly preferably 50% by mass or more, based on the total of water and organic solvent. The higher the ratio of the organic solvent, the more likely it is that uniform carboxymethyl group substitution will occur, and the more advantageous it is that carboxymethylated cellulose with stable quality can be obtained. The upper limit of the ratio of the organic solvent is not limited, and may be, for example, 99% by mass or less. Considering the cost of the organic solvent to be added, it is preferably 90% by mass or less, more preferably 85% by mass or less, even more preferably 80% by mass or less, and even more preferably 70% by mass or less.

[0041] When the crystallinity of carboxymethylated cellulose is to be a high value such as 50% or more, the reaction medium during carboxymethylation (a mixed solvent of water and an organic solvent, etc., not containing cellulose) preferably has a lower proportion of water (in other words, a higher proportion of organic solvent) than the reaction medium during mercerization. By satisfying this range, the crystallinity of the obtained carboxymethylated cellulose is easily maintained. In addition, when the reaction medium during carboxymethylation has a lower proportion of water (a higher proportion of organic solvent) than the reaction medium during mercerization, when transferring from the mercerization reaction to the carboxymethylation reaction, a mixed solvent for the carboxymethylation reaction can be formed by a simple means of adding a desired amount of organic solvent to the reaction system after the completion of the mercerization reaction.

[0042] A mixed solvent of water and an organic solvent is prepared, and a carboxymethylating agent is added to the mercerized cellulose, followed by stirring for 15 minutes to 4 hours, preferably 15 minutes to 1 hour, while maintaining a constant temperature, preferably in the range of 10 to 40°C. The liquid containing the mercerized cellulose and the carboxymethylating agent are preferably mixed in several batches or by dropwise addition, in order to prevent the reaction mixture from becoming too hot. After adding the carboxymethylating agent and stirring for a certain period of time, the temperature is raised if necessary to a reaction temperature of 30 to 90°C, preferably 40 to 90°C, more preferably 60 to 80°C, and an etherification (carboxymethylation) reaction is carried out for 30 minutes to 10 hours, preferably 1 hour to 4 hours, to obtain carboxymethylated cellulose. By raising the temperature during the carboxymethylation reaction, the etherification reaction can be advantageously carried out efficiently in a short time.

[0043] In the carboxymethylation, the reactor used in the mercerization may be used as it is, or a separate reactor capable of mixing and stirring the above-mentioned components while controlling the temperature may be used.

[0044] After the reaction is completed, the remaining alkali metal salt may be neutralized with a mineral acid or an organic acid. If necessary, by-products such as inorganic salts and organic acid salts may be removed by washing with aqueous methanol, and the product may be dried, pulverized, and classified to obtain carboxymethyl cellulose or a salt thereof. Examples of devices used in dry pulverization include impact mills such as hammer mills and pin mills, media mills such as ball mills and tower mills, and jet mills. Examples of devices used in wet pulverization include homogenizers, mass colloiders, and pearl mills.

[0045] (water) The rice flour noodles of the present invention may be fresh noodles containing water, or may be dried noodles obtained by drying fresh noodles. In addition to tap water, any water normally used in food production, such as distilled water or ion-exchanged water, may be used as the water. When fresh noodles are used, the water content is preferably 30 to 100 parts by mass, and more preferably 30 to 70 parts by mass, per 100 parts by mass of cereal flour. When dried, the fresh noodles may be dried by a known drying method such as hot air drying. In the present invention, dried noodles refer to noodles that have been dried until the water content is 20 parts by mass or less per 100 parts by mass of cereal flour.

[0046] Other ingredients used in the rice flour noodles of the present invention are not particularly limited, and similar to ordinary rice flour noodles, other additives can be used depending on the desired flavor, texture, physical properties, appearance, etc. Examples include protein materials such as soy protein, egg yolk powder, egg white powder, whole egg powder, skim milk powder, etc.; fats and oils such as animal and vegetable oils and fats, and powdered oils and fats; dietary fiber, leavening agents, emulsifiers, kansui, salt, sugars, sweeteners, spices, seasonings, vitamins, minerals, colorants, flavorings, dextrin, alcohol, enzyme preparations, etc., and these can be used alone or in combination of two or more. The amount of other additives to be added is usually about 0 to 30 parts by mass per 100 parts by mass of grain flour.

[0047] (Method of manufacturing rice flour noodles) The method for producing rice flour noodles of the present invention includes the steps of preparing a rice flour composition containing 0.1 to 10 parts by mass of carboxymethyl cellulose and a salt thereof per 100 parts by mass of grain flour having rice flour as the main component, adding 50 to 100 parts by mass of water per 100 parts by mass of the grain flour to the obtained rice flour composition, and kneading the mixture to obtain a rice flour dough, and rolling the obtained rice flour dough into a noodle shape.

[0048] (Step of preparing rice flour composition) In this step, carboxymethyl cellulose and its salts are added in an amount of 0.1 to 10 parts by mass, preferably 0.1 to 5 parts by mass, and more preferably 0.5 to 3 parts by mass, per 100 parts by mass of cereal flour mainly composed of rice flour to prepare a rice flour composition. In this step, other additives may be added as necessary.

[0049] (Process for obtaining rice flour dough) In this step, 30 to 100 parts by mass, preferably 30 to 70 parts by mass of water is added to the obtained rice flour composition per 100 parts by mass of cereal flour, and then kneaded to obtain rice flour dough. The temperature of the water used during kneading is not particularly limited, but it is preferably 80 to 100°C from the viewpoint of the gelatinization temperature of rice starch.

[0050] (Molding process) In this step, the obtained rice flour dough is formed into a noodle shape. As a method for forming the rice flour dough into a noodle shape, known noodle-making methods such as rolling, roll-type, and extrusion-type noodle-making can be used. For example, the rice flour dough is rolled by passing it through a rolling roll to form a noodle band of a desired thickness, and then the noodle band is cut into noodle strings using a noodle-making machine or the like, and the noodle strings are cut into a desired length as necessary to obtain rice flour noodles formed into a noodle shape. In another embodiment, rice flour noodles formed into a noodle shape by extruding the rice flour dough through a hole or the like may be produced. In this step, dusting flour may be used as necessary. As the dusting flour, those exemplified as grain flours can be used as appropriate. The grain flour used in the dusting flour may be different in type and composition from the grain flour used in the rice flour composition.

[0051] The rice flour noodles of the present invention contain carboxymethyl cellulose and a salt thereof in specific proportions, which increases the strength of the noodles, making them less likely to break during production and easier to handle and work with. The cooked rice flour noodles obtained by cooking the resulting rice flour noodles maintain their length, have a texture unique to rice flour, and are excellent in taste. EXAMPLES

[0052] The present invention will be described in detail below using examples, but the present invention is not limited to the following examples. In addition, unless the method of measurement / calculation of each value in each example is specifically stated, it is measured / calculated by the method described in the specification.

[0053] (Production Example 1) A solution of 70 parts of isopropyl alcohol (IPA) and 68 parts of sodium hydroxide dissolved in 30 parts of water was added to a twin-axis kneader with the rotation speed adjusted to 100 rpm, and 100 parts of hardwood pulp (LBKP, manufactured by Nippon Paper Industries Co., Ltd.) was added based on the dry mass when dried at 100°C for 60 minutes. The mixture was stirred and mixed at 30°C for 90 minutes to prepare mercerized cellulose. 80 parts of monochloroacetic acid dissolved in 230 parts of IPA was further added while stirring, and after stirring for 30 minutes, the mixture was heated to 70°C and subjected to a carboxymethylation reaction for 90 minutes. The concentration of IPA in the reaction medium during the carboxymethylation reaction was 91%. After the reaction was completed, the mixture was neutralized with acetic acid to a pH of about 7, deliquored, dried, and pulverized to obtain carboxymethyl cellulose sodium salt 1 (CMC1). The CMC1 had a carboxymethyl substitution degree of 0.28, a B-type viscosity of 80 mPa s in an aqueous solution with a solids concentration of 1 mass% measured with a B-type viscometer at 25°C, a crystallinity of cellulose type I of 0%, an average particle size of 50 μm, and a moisture content of less than 10%.

[0054] (Production Example 2) A twin-shaft kneader with the rotation speed adjusted to 100 rpm was charged with 20 parts of sodium hydroxide dissolved in 100 parts of water, and 100 parts of hardwood pulp (LBKP, manufactured by Nippon Paper Industries Co., Ltd.) was added based on the dry mass when dried at 100°C for 60 minutes. The mixture was stirred and mixed at 30°C for 90 minutes to prepare mercerized cellulose. 230 parts of isopropanol (IPA) and 60 parts of sodium monochloroacetate were further added while stirring, and after stirring for 30 minutes, the mixture was heated to 70°C and carboxymethylation reaction was carried out for 90 minutes. The concentration of IPA in the reaction medium during the carboxymethylation reaction was 70%. After the reaction was completed, the mixture was neutralized with acetic acid to about pH 7, deliquored, dried, and pulverized to obtain carboxymethylated cellulose sodium salt 2 (CMC2) with a carboxymethyl substitution degree of 0.32, a 1% viscosity of 30 mPa·s, a crystallinity of cellulose I type 71%, an average particle size of 50 μm, and a moisture content of less than 10%.

[0055] (Production Example 3) Hardwood-derived pulp was reacted for 2 hours at 95° C. under conditions of a pulp concentration of 5.5% and a hydrochloric acid concentration of 0.15 N. After the reaction was completed, the sample was neutralized with sodium hydroxide, thoroughly washed with water, and then air-dried for about 1 day at a temperature condition of 60° C. The dried sample was mechanically pulverized using a hammer mill (Hosokawa Micron Corporation, AP-S type) to obtain powdered cellulose 1 with an average particle size of 36 μm.

[0056] (Production Example 4) Hardwood-derived pulp was reacted for 2 hours at 95° C. under conditions of a pulp concentration of 5.5% and a hydrochloric acid concentration of 1.2 N. After the reaction was completed, the sample was neutralized with sodium hydroxide, thoroughly washed with water, and then dried with air at a temperature of 60° C. for about 1 day. The dried sample was mechanically pulverized using a hammer mill (Hosokawa Micron Corporation, AP-S type) to obtain powdered cellulose 2 with an average particle size of 24 μm.

[0057] (Examples and Comparative Examples) (Production of rice flour noodles) (Noodle making process) The ingredients other than water were weighed out in the blending ratio shown in Table 1, thoroughly mixed and homogenized to prepare a rice flour composition. The mixture was placed in a food mold, and while mixing using a mixer, 100°C water was added little by little, and further kneaded for 15 minutes to obtain rice flour dough. The kneaded rice flour dough was divided into about 80g portions, put into bags, vacuum-packed, and rolled using a rolling pin. The obtained sheet-like dough was taken out of the bag, and further rolled using a pasta machine (Marcato, Atlas 150) with a thickness setting of 4.8 mm to obtain a sheet-like dough. After that, it was cut into noodles with a cutter attached to the pasta machine to obtain rice flour noodles. During rolling using the pasta machine, 10 parts by mass or less of processed starch was used as a dusting powder for 100 parts by mass of rice flour. The obtained rice flour noodles were frozen in a freezer, and after completely freezing, they were put into bags and stored frozen.

[0058] (Cooking rice noodles) (Boiling and cooling process) The frozen rice flour noodles were boiled in boiling water for 1 minute while loosening them with chopsticks. After the boiling time had elapsed, the rice flour noodles were poured into a colander, and while running water, the noodles were loosened by hand, washed with water, and cooled to obtain cooked rice flour noodles.

[0059] The following evaluations were carried out in the examples and comparative examples. For comparison, rice flour noodles without CMC or powdered cellulose were also produced in the same manner as above with the blending ratios shown in Table 1 as a control, and were also evaluated in the same manner.

[0060] (Workability) The ease of handling of rice flour noodles during the boiling and cooling processes was evaluated according to the following criteria. The results are shown in Table 1. Note that ease of handling of noodles indicates that the noodles are strong. A: The noodles are hard to break and easy to handle. B: The noodles break easily and are difficult to handle.

[0061] (Tasting evaluation) The frozen rice flour noodles were boiled in boiling water for 1 minute, then rinsed and cooled to obtain cooked rice flour noodles. A taste test was conducted on the cooked rice flour noodles. The taste test was conducted on the cold noodles dipped in soup. The results are shown below. The overall evaluation was expressed in a range of 1 to 10 points. A higher score is better. The rice flour noodles of Example 1 were smooth and chewy. The rice flavor was noticeable. Overall rating was 5 points. The rice flour noodles of Example 2 were smooth and chewy. The rice flavor was slightly weaker than that of Example 1. Overall rating: 4 points. The rice flour noodles of Comparative Example 1 had a mochi-like texture and were not smooth. They were rough when chewed. Compared to the control, they were a little chewier and had a slight rice flavor. Overall rating: 3 points. The rice flour noodles of Comparative Example 2 were not smooth and had a texture similar to mochi. They were rough when chewed. The degree of roughness was slightly better than that of the control. Also, compared to the control, they were a little chewier and had a slight rice taste. Overall rating was 3 points. The control rice flour noodles had a mochi-like texture and were not smooth. They were rough when chewed. The rice flavor was weak and only slightly noticeable. Overall rating: 3 points.

[0062] [Table 1]

[0063] As can be seen from Table 1, the rice flour noodles of Examples 1 and 2 of the present invention, which contain carboxymethylated cellulose and a salt thereof in specific proportions, are easier to handle and less likely to break when loosened with chopsticks during boiling or by hand when rinsing with water, compared to the rice flour noodles of Comparative Examples 1 and 2, and have excellent workability during production. Furthermore, when made into cooked rice flour noodles, the texture unique to rice flour was felt and the taste was also excellent. This shows that rice flour noodles containing carboxymethylated cellulose and a salt thereof have the excellent effects of being easy to handle due to the strength of the noodles, and further having excellent texture and taste.

[0064] (Appearance of cooked rice noodles) After the boiling and cooling process, cooked rice flour noodles were washed in water to loosen them and cooled, and photographs of them being picked up with chopsticks were taken and shown in Figure 1. The appearance of the noodles picked up with chopsticks immediately after cooling and 5 minutes after cooling was compared.

[0065] From the photograph of FIG. 1 taken immediately after cooling, it can be seen that the cooked rice flour noodles of Examples 1 and 2 maintain their noodle length, whereas the cooked rice flour noodles of Comparative Examples 1 and 2 and the control are shorter in length. This is because the rice flour noodles of Comparative Examples 1 and 2 and the control are easily torn during the boiling and cooling process, and are torn by their own weight when picked up with chopsticks. In contrast, the rice flour noodles of Examples 1 and 2 are stronger, so they are less likely to shorten and are easier to handle than the rice flour noodles of Comparative Examples 1 and 2 and the control. Furthermore, comparing the photographs of FIG. 1 taken immediately after cooling and after 5 minutes, it can be seen that in both cases, the noodles after 5 minutes are shorter than those taken immediately after cooling. This is because the noodles tend to stick together over time, and are torn when picked up with chopsticks.

Claims

1. The rice flour noodles are characterized by containing 0.1 to 10 parts by mass of carboxymethyl cellulose and its salts per 100 parts by mass of cereal flour mainly composed of rice flour.

2. 2. The rice flour noodles according to claim 1, wherein the carboxymethyl cellulose and salts thereof have a degree of carboxymethyl substitution of 0.01 or more and 0.50 or less.

3. 2. The rice flour noodles according to claim 1, characterized in that the carboxymethyl cellulose and its salt are contained in an amount of 0.1 to 5 parts by mass per 100 parts by mass of cereal flour mainly composed of rice flour.

4. A step of preparing a rice flour composition containing 0.1 to 10 parts by mass of carboxymethyl cellulose and its salt per 100 parts by mass of a grain flour mainly composed of rice flour; adding water to the rice flour composition in an amount of 30 to 100 parts by mass per 100 parts by mass of cereal flour, and then kneading the mixture to obtain rice flour dough; and forming the rice flour dough into noodles.

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