JP7725982B2 - Dried noodles - Google Patents

Description

The present invention relates to dried noodles such as udon, soba, somen, and hiyamugi.

Noodles are a popular staple food, and dried noodles and instant noodles are particularly popular because they are dry and can be stored for long periods of time, and are also easy to prepare.

Dried noodles and instant noodles are generally produced as follows. Wheat flour and other ingredients are usually mixed with water, salt, alkaline water, etc. to create noodle dough, which is then rolled and cut out to produce fresh noodle strands. The cut raw noodle strands are generally steamed with saturated steam, then seasoned as needed, cut to the specified length, measured out as one serving, and dried with hot air or other means to produce dried noodles or instant noodles.

Dried noodles are boiled in hot water before eating. Somen and hiyamugi are boiled, then rinsed in cold water and cooled before eating.

Patent Document 1 describes the addition of water-insoluble cellulose to dry noodles, which are boiled, frozen, and then thawed in water to prevent the texture from deteriorating.

Japanese Patent Application Laid-Open No. 2020-120617

However, dried noodles are sometimes boiled in hot water, then stored in the refrigerator for 1-2 days before being sold in stores, but this can cause problems with noodles that lose their firmness and other texture.

Therefore, the present invention aims to provide dried noodles that do not lose texture, such as firmness, even when stored in a refrigerator after being boiled in hot water.

(1) Dried noodles containing cellulose nanofibers and cereal flour.
(2) The dried noodles according to (1), wherein the cellulose nanofibers are anion-modified cellulose nanofibers.
(3) Dried noodles according to (1) or (2), wherein the anion-modified cellulose nanofibers are cellulose nanofibers having a carboxyl group or cellulose nanofibers having a carboxyalkyl group.
(4) The dried noodles according to (3), wherein the anion-modified cellulose nanofibers are carboxymethylated cellulose nanofibers having a degree of carboxymethyl substitution in the range of 0.01 to 0.50.
(5) The dried noodles according to any one of (1) to (4), further containing carboxymethyl cellulose.
(6) The dried noodles according to any one of (1) to (5), wherein the dried noodles are one type selected from the group consisting of udon, soba, somen, hiyamugi, Chinese noodles, yakisoba, macaroni, spaghetti, pasta, Korean hiyashi noodles, kudzu noodles, glass noodles, rice vermicelli, gyoza wrappers, shumai wrappers, and wontons.
(7) The dried noodles according to any one of (1) to (6), characterized in that the dried noodles are instant noodles.

The present invention makes it possible to provide dried noodles that do not lose texture, such as firmness, even when stored in a refrigerator after being boiled in hot water.

The present invention will be explained in detail below. In this invention, "to" includes the extreme values. In other words, "X to Y" includes the values X and Y at both ends.

The dried noodles of the present invention contain grain flour, cellulose nanofiber, and, if necessary, other ingredients. The cellulose nanofiber contained in the dried noodles is water-insoluble and does not dissolve or deform when the dried noodles are rehydrated in hot water. This means that the firmness of the noodles is unlikely to decrease even when stored in the freezer after boiling.

Dried noodles in this invention refer to foods generally referred to as dried noodles, regardless of their form or type, that are made primarily from grain flour and have been dried to a moisture content of 15% or less. Specific examples include udon, soba, Chinese noodles, hiyamugi, somen, Chinese noodles, yakisoba, macaroni, spaghetti, Korean hiyashi noodles, kudzu noodles, glass noodles, rice vermicelli, gyoza wrappers, shumai wrappers, wontons, etc. Examples of forms include dried noodles and instant noodles. Dried noodles are an example of noodles in which the effects of the present invention are particularly pronounced.

The main ingredients of dried noodles include wheat flour (strong flour, semi-strong flour, medium-strength flour, soft flour, durum wheat flour, whole wheat flour, etc.), rice flour, buckwheat flour, and other cereal flours. If necessary, unprocessed starches such as potato starch, sweet potato starch, tapioca starch, corn starch, waxy corn starch, rice starch, and mung bean starch can also be used, as well as processed starches produced by etherifying, esterifying, oxidizing, bleaching, crosslinking, pregelatinizing, or other processes, either alone or in combination. Salt and brine can also be added as additives. Other ingredients that can be used include thickening agents such as phosphates, alginic acid, caprobean gum, guar gum, tamarind seed gum, pectin, xanthan gum, carrageenan, and curdlan, emulsifiers, oils and fats, egg whites, milk proteins, coloring agents, antioxidants, wheat proteins, and other physiologically active ingredients such as vitamins, calcium, iron, and other seasonings, as well as other ingredients.

(Cellulose nanofiber)
In the present invention, cellulose nanofibers (hereinafter sometimes referred to as CNF) are fine fibers with a fiber width of about 1 to 500 nm, which are made by pulp, a cellulose-based raw material, being refined to the nanometer level. The average fiber diameter and average fiber length of cellulose nanofibers can be obtained by averaging the fiber diameters and fiber lengths obtained from the observation of each fiber using an atomic force microscope (AFM) or a transmission electron microscope (TEM). The average aspect ratio of cellulose nanofibers is usually 50 or more. There is no particular upper limit, but it is usually 1000 or less. The average aspect ratio can be calculated using the following formula:
Aspect ratio = average fiber length/average fiber diameter

Cellulose nanofibers are obtained by applying mechanical force to pulp to reduce its size, and can be obtained by defibrating unmodified cellulose or modified cellulose such as carboxylated cellulose (also called oxidized cellulose), carboxymethylated cellulose, anionically modified cellulose such as cellulose with introduced phosphate ester groups, or cationized cellulose. The average fiber length and average fiber diameter of the fine fibers can be adjusted by oxidation treatment and defibration treatment. In the present invention, it is preferable to use carboxymethylated (CM) cellulose nanofibers obtained by defibrating carboxymethylated cellulose obtained by carboxymethylation treatment.

(cellulose raw material)
Examples of cellulose raw materials for producing the cellulose nanofibers used in the present invention include those derived from plant materials (e.g., wood, bamboo, hemp, jute, kenaf, agricultural waste, cloth, pulp), animal materials (e.g., sea squirts), algae, and organisms produced by microorganisms (e.g., acetic acid bacteria (Acetobacter)). Examples of pulp include unbleached softwood kraft pulp (NUKP), bleached softwood kraft pulp (NBKP), unbleached hardwood kraft pulp (LUKP), bleached hardwood kraft pulp (LBKP), unbleached softwood sulfite pulp (NUSP), bleached softwood sulfite pulp (NBSP), thermomechanical pulp (TMP), recycled pulp, and waste paper. Although all of these can be used, cellulose fibers derived from plants or microorganisms are preferred, and plant-derived cellulose fibers are more preferred.

(carboxymethylation)
When carboxymethylated cellulose nanofibers are used in the present invention, the carboxymethylated cellulose may be obtained by carboxymethylating the above-mentioned cellulose raw material using a known method, or a commercially available product may be used. In either case, the degree of carboxymethyl substitution per anhydroglucose unit of the cellulose is preferably 0.01 to 0.50. An example of a method for producing such carboxymethylated cellulose is as follows: Cellulose is used as the starting material, and 3 to 20 times by mass of water or a lower alcohol is used as the solvent. Specifically, water, methanol, ethanol, N-propyl alcohol, isopropyl alcohol, N-butanol, isobutanol, tertiary butanol, etc. can be used alone or in combination of two or more. When a mixed solvent of water and a lower alcohol is used, the lower alcohol is mixed in a ratio of 60 to 95% by mass. As the mercerizing agent, 0.5 to 20 times the molar amount of an alkali metal hydroxide, specifically sodium hydroxide or potassium hydroxide, is used per anhydroglucose residue of the starting material. The starting material, solvent, and mercerizing agent are mixed, and a mercerization treatment is carried out at a reaction temperature of 0 to 70°C, preferably 10 to 60°C, for a reaction time of 15 minutes to 8 hours, preferably 30 minutes to 7 hours. Thereafter, a carboxymethylating agent is added at 0.05 to 10.0 times the moles per glucose residue, and an etherification reaction is carried out at a reaction temperature of 30 to 90°C, preferably 40 to 80°C, for a reaction time of 30 minutes to 10 hours, preferably 1 hour to 4 hours.

<Carboxymethylated cellulose nanofiber>
The carboxymethylated cellulose nanofibers of the present invention maintain at least a portion of their fibrous shape even when dispersed in water. That is, when an aqueous dispersion of the carboxymethylated cellulose nanofibers is observed under an electron microscope, a fibrous substance can be observed. Furthermore, when the carboxymethylated cellulose nanofibers are measured by X-ray diffraction, a peak corresponding to cellulose type I crystals can be observed.

<Crystallization degree of cellulose type I>
The degree of crystallinity of cellulose in the carboxymethylated cellulose nanofibers used in the present invention is preferably 40% or more, more preferably 50% or more, for crystalline type I. When the degree of crystallinity of type I cellulose is as high as 40% or more, a high proportion of cellulose maintains its crystalline structure without dissolving in solvents such as water, resulting in high thixotropy and making it suitable for viscosity-adjusting applications such as thickeners. Furthermore, for example, but not limited to, when added to gel-like substances (e.g., foods, cosmetics, etc.), it has the advantage of imparting excellent shape retention. The crystallinity of cellulose can be controlled by the concentration of the mercerizing agent, the treatment temperature, and the degree of carboxymethylation. Because high concentrations of alkali are used in mercerization and carboxymethylation, type I cellulose crystals are likely to be converted to type II cellulose crystals. However, the desired crystallinity can be maintained by adjusting the degree of denaturation, such as by adjusting the amount of alkali (mercerizing agent) used. The upper limit of the crystallinity of type I cellulose is not particularly limited. A practical upper limit is thought to be approximately 90%.

The method for measuring the crystallinity of cellulose type I of carboxymethylated cellulose nanofiber is as follows:
The sample is placed in a glass cell and measured using an X-ray diffraction measurement device (LabX XRD-6000, manufactured by Shimadzu Corporation). The degree of crystallinity is calculated using the method of Segal et al., where the diffraction intensity at 2θ = 10° to 30° in the X-ray diffraction pattern is used as a baseline, and the degree of crystallinity is calculated using the diffraction intensity of the 002 plane at 2θ = 22.6° and the diffraction intensity of the amorphous portion at 2θ = 18.5° according to the following formula:

Xc=(I002c−Ia)/I002c×100
Xc = Crystallinity of cellulose type I (%)
I002c: 2θ=22.6°, diffraction intensity of the 002 plane Ia: 2θ=18.5°, diffraction intensity of the amorphous portion

The proportion of type I crystals in carboxymethylated cellulose nanofibers is typically the same as that in the carboxymethyl cellulose before it is made into nanofibers.

<Degree of carboxymethyl substitution>
The carboxymethylated cellulose nanofibers used in the present invention preferably have a degree of carboxymethyl substitution per anhydroglucose unit of cellulose of 0.50 or less. If the degree of carboxymethyl substitution exceeds 0.50, it is believed that the cellulose will dissolve in water and will no longer be able to maintain its fiber shape. In consideration of operability, the degree of substitution is preferably 0.01 to 0.50, more preferably 0.02 to 0.50, even more preferably 0.05 to 0.40, and even more preferably 0.10 to 0.40. By introducing carboxymethyl groups into cellulose, the cellulose molecules electrically repel each other, making it possible to defibrate the cellulose into nanofibers. However, if the degree of carboxymethyl substitution per anhydroglucose unit is less than 0.01, defibration will be insufficient, and highly transparent cellulose nanofibers may not be obtained. While it has been difficult to obtain carboxymethylated cellulose nanofibers having a cellulose type I crystallinity of 60% or more when the degree of carboxymethyl substitution is in the range of 0.20 to 0.40 using conventional aqueous methods, the present inventors have discovered that, for example, by the method described below, it is possible to produce carboxymethylated cellulose nanofibers having a carboxymethyl substitution in the range of 0.20 to 0.40 and a cellulose type I crystallinity of 60% or more. The degree of carboxymethyl substitution can be adjusted by controlling the amount of carboxymethylating agent added to the reaction, the amount of mercerizing agent, the composition ratio of water to organic solvent, etc.

In the present invention, anhydroglucose units refer to the individual anhydroglucose (glucose residues) that make up cellulose. Furthermore, the degree of carboxymethyl substitution (also referred to as the degree of etherification) refers to the proportion of hydroxyl groups in the glucose residues that make up cellulose that have been substituted with carboxymethyl ether groups (the number of carboxymethyl ether groups per glucose residue). The degree of carboxymethyl substitution is sometimes abbreviated as DS.

The degree of carboxymethyl substitution is measured as follows:
Approximately 2.0 g of sample is weighed out and placed in a 300 mL Erlenmeyer flask with a stopper. 100 mL of a solution of 1000 mL of nitric acid methanol and 100 mL of special-grade concentrated nitric acid is added and shaken for 3 hours to convert the carboxymethylated cellulose nanofiber salt (CMC) into H-CMC (hydrogen-type carboxymethylated cellulose nanofiber). 1.5 to 2.0 g of the bone-dry H-CMC is weighed out and placed in a 300 mL Erlenmeyer flask with a stopper. The H-CMC is moistened with 15 mL of 80% methanol, 100 mL of 0.1 N NaOH is added, and the mixture is shaken at room temperature for 3 hours. Using phenolphthalein as an indicator, excess NaOH is back-titrated with 0.1 N H ₂ SO ₄ , and the degree of carboxymethyl substitution (DS value) is calculated using the following formula:
A=[(100×F'-0.1N-H ₂ SO ₄ (mL)×F)×0.1]/(H-CMC
Absolute dry mass (g)
Degree of carboxymethyl substitution=0.162×A/(1−0.058×A)
F': Factor of 0.1N H ₂ SO ₄ F: Factor of 0.1N NaOH.

The degree of carboxymethyl substitution in carboxymethylated cellulose nanofibers is typically the same as the degree of carboxymethyl substitution in the carboxymethylated cellulose before it was made into nanofibers.

<Fiber diameter, aspect ratio>
The carboxymethyl cellulose nanofibers used in the present invention have a nanoscale fiber diameter, preferably 3 nm to 500 nm, more preferably 3 nm to 150 nm, even more preferably 3 nm to 20 nm, even more preferably 5 nm to 19 nm, and even more preferably 5 nm to 15 nm.

The aspect ratio of carboxymethylated cellulose nanofibers is not particularly limited, but is preferably 350 or less, more preferably 300 or less, even more preferably 200 or less, even more preferably 120 or less, even more preferably 100 or less, and even more preferably 80 or less. An aspect ratio of 350 or less means that the fibers are not excessively long, reducing entanglement between fibers and reducing the formation of cellulose nanofiber clumps, making them suitable for use as an additive. Furthermore, their high fluidity makes them easy to use even at high concentrations, offering the advantage of being easy to use in applications requiring a high solids content. The lower limit of the aspect ratio is not particularly limited, but is preferably 25 or more, more preferably 30 or more. An aspect ratio of 25 or more provides the effect of improved thixotropy due to the fibrous shape. The aspect ratio of carboxymethylated cellulose nanofibers can be controlled by the mixing ratio of solvent and water during carboxymethylation, the amount of chemicals added, and the degree of carboxymethylation. They can also be produced, for example, by the manufacturing method described below.

The average fiber diameter and average fiber length of carboxymethyl cellulose nanofibers can be measured by analyzing 200 randomly selected fibers using an atomic force microscope (AFM) if the diameter is 20 nm or less, or a field emission scanning electron microscope (FE-SEM) if the diameter is 20 nm or more, and calculating the average. The aspect ratio can be calculated using the following formula:
Aspect ratio = average fiber length/average fiber diameter.

(defibration)
The cellulose raw material may be defibrated either before or after the denaturation treatment. Defibration may be performed once or multiple times. In the case of multiple times, each defibration may be performed at any time.

The equipment used for defibration is not particularly limited, but examples include high-speed rotation, colloid mill, high-pressure, roll mill, and ultrasonic types of equipment. High-pressure or ultra-high-pressure homogenizers are preferred, and wet high-pressure or ultra-high-pressure homogenizers are more preferred. The equipment is preferably capable of applying strong shear forces to the cellulose raw material or modified cellulose (usually a dispersion). The pressure that the equipment can apply is preferably 50 MPa or more, more preferably 100 MPa or more, and even more preferably 140 MPa or more. The equipment is preferably a wet high-pressure or ultra-high-pressure homogenizer that can apply the above pressure and strong shear forces to the cellulose raw material or modified cellulose (usually a dispersion). This allows for efficient defibration.

When defibrating a dispersion of cellulose raw materials, the solids concentration of the cellulose raw materials in the dispersion is typically 0.1% by mass or more, preferably 0.2% by mass or more, and more preferably 0.3% by mass or more. This ensures an appropriate amount of liquid relative to the amount of cellulose fiber raw material, which is efficient. The upper limit is typically 10% by mass or less, and preferably 6% by mass or less. This allows fluidity to be maintained.

If necessary, preliminary treatment may be carried out prior to defibration (preferably with a high-pressure homogenizer) or, if necessary, prior to dispersion treatment prior to defibration. The preliminary treatment may be carried out using a mixing, stirring, emulsifying, or dispersing device such as a high-speed shear mixer.

(Drying)
The cellulose nanofibers used in the present invention can be used in the form of a dispersion obtained after defibration, or they can be dried and redispersed in water as needed. The drying method is not particularly limited, and known methods such as freeze drying, spray drying, tray drying, drum drying, belt drying, a method of thinly spreading the nanofibers on a glass plate or the like and drying them, fluidized bed drying, microwave drying, and heated fan-type reduced pressure drying can be used. After drying, the nanofibers can be pulverized as needed using a cutter mill, hammer mill, pin mill, jet mill, or the like. The method for redispersing the nanofibers in water is also not particularly limited, and known dispersing devices can be used.

The cellulose nanofibers used in the present invention may be in the form of a dispersion or powder, but from the perspective of excellent workability during confectionery production, it is preferable to use them in the form of a dispersion.

In the present invention, the amount of cellulose nanofibers to be blended is preferably 0.01 to 5% by mass, more preferably 0.05 to 3% by mass, and even more preferably 0.1 to 2% by mass, calculated as solid content relative to the grain flour.

The cellulose nanofibers of the present invention may contain other components as needed. For example, when producing a powder, it is preferable to add a water-soluble polymer to the cellulose nanofiber dispersion before drying, as this improves redispersibility.

<Water-soluble polymer>
Examples of water-soluble polymers include cellulose derivatives (carboxymethylcellulose, methylcellulose, hydroxypropylcellulose, ethylcellulose), xanthan gum, xyloglucan, dextrin, dextran, carrageenan, locust bean gum, alginic acid, alginates, pullulan, starch, potato starch, arrowroot flour, corn starch, gum arabic, locust bean gum, gellan gum, polydextrose, pectin, chitin, water-soluble chitin, chitosan, casein, albumin, soy protein lysate, peptone, tamarind gum, and guar gum. Among these, cellulose derivatives are preferred in terms of their affinity with carboxymethylated cellulose nanofibers, and carboxymethylcellulose and its salts are particularly preferred. It is believed that water-soluble polymers such as carboxymethylcellulose and its salts penetrate between carboxymethylated cellulose nanofibers, increasing the distance between the nanofibers and thereby improving redispersibility.

When carboxymethyl cellulose or a salt thereof is used as the water-soluble polymer, it is preferable to use a carboxymethyl cellulose with a degree of carboxymethyl group substitution per anhydroglucose unit of 0.55 to 1.6, more preferably 0.55 to 1.1, and even more preferably 0.65 to 1.1. Furthermore, carboxymethyl cellulose with longer molecules (higher viscosity) is preferred because it is more effective at increasing the distance between nanofibers. Furthermore, the Brookfield viscosity of a 1% by mass aqueous solution of carboxymethyl cellulose at 25°C and 60 rpm is preferably 3 mPa·s to 14,000 mPa·s, more preferably 7 mPa·s to 14,000 mPa·s, and even more preferably 1,000 mPa·s to 8,000 mPa·s. Note that the "carboxymethyl cellulose or a salt thereof" referred to here as the water-soluble polymer is completely soluble in water, and is therefore distinct from the carboxymethyl cellulose nanofibers described above, the fiber shape of which can be confirmed in water.

The amount of water-soluble polymer blended is preferably 5% to 300% by mass, more preferably 20% to 300% by mass, even more preferably 25% to 200% by mass, and even more preferably 25% to 60% by mass, relative to the cellulose nanofiber (bone dry solids content).

The dried noodles of the present invention can be produced using conventionally known production methods. For example, this can be done as follows. First, a noodle dough containing the ingredients contained in the dried noodles of the present invention is prepared. From this noodle dough, fresh noodle strands of the desired shape are produced using conventionally known methods. The resulting fresh noodle strands are then subjected to both a process of boiling in hot water or a steaming process, and a process of drying using hot air or deep-frying, thereby achieving final starch gelatinization. Starch gelatinization in the steaming process is minimized, that is, the starch granules are brought to a state where they are only swollen to the limit without being disintegrated by the heat of the steaming process. The noodles are then dried. The drying process can be, for example, high-temperature drying, such as hot air drying or deep-frying drying.

The present invention will be explained in more detail below using examples, but the present invention is not limited to these examples.

(Method for measuring degree of carboxymethyl substitution)
1) Approximately 2.0 g of carboxymethylated cellulose fiber (bone dry) is weighed out and placed in a 300 mL Erlenmeyer flask with a stopper.
2) 100 mL of a solution prepared by adding 100 mL of special-grade concentrated nitric acid to 1000 mL of nitric acid methanol is added, and the mixture is shaken for 3 hours to convert the carboxymethyl cellulose salt (carboxymethyl cellulose) into hydrogenated carboxymethyl cellulose.
3) Accurately weigh out 1.5 to 2.0 g of hydrogenated carboxymethyl cellulose (bone dry) and place it in a 300 mL Erlenmeyer flask with a stopper.
4) Wet the hydrogenated carboxymethyl cellulose with 15 mL of 80% methanol, add 100 mL of 0.1 N NaOH, and shake at room temperature for 3 hours.
5) Back-titrate excess NaOH _with 0.1N _H2SO4 using phenolphthalein as indicator.
6) The degree of carboxymethyl substitution (DS) is calculated by the following formula:
A = [(100 × F' - (0.1 N H ₂ SO ₄ ) (mL) × F) × 0.1] / (bone-dry mass (g) of hydrogenated carboxymethyl cellulose)
DS=0.162×A/(1-0.058×A)
A: Amount (mL) of 1 N NaOH required to neutralize 1 g of hydrogenated carboxymethyl cellulose
F': Factor of 0.1N _H2SO4 F: Factor of 0.1N NaOH (Method for measuring average _fiber diameter and aspect ratio)
The average fiber diameter and average fiber length of CNF were analyzed using an atomic force microscope (AFM) for 200 randomly selected fibers. The aspect ratio was calculated using the following formula:
Aspect ratio = average fiber length/average fiber diameter

[Example 1]
(Preparation of carboxymethylated cellulose nanofibers)
A 5L twin-screw kneader with the rotation speed adjusted to 100 rpm was charged with 1,089 parts of isopropanol (IPA) and a solution of 31 parts of sodium hydroxide dissolved in 121 parts of water, and 200 parts of hardwood pulp (LBKP, manufactured by Nippon Paper Industries Co., Ltd.) dried at 100°C for 60 minutes (dry mass). The mixture was stirred and mixed at 30°C for 60 minutes to prepare mercerized cellulose. Further, 117 parts of sodium monochloroacetate was added with stirring, and after stirring at 30°C for 30 minutes, the mixture was heated to 70°C over 30 minutes and allowed to undergo a carboxymethylation reaction at 70°C for 60 minutes. The proportion of water in the reaction medium during the mercerization reaction and the carboxymethylation reaction was 10% by mass. After completion of the reaction, the mixture was neutralized, washed with 65% aqueous methanol, deliquored, dried, and pulverized to obtain a sodium salt of carboxymethylated cellulose with a carboxymethyl substitution degree of 0.27 and a crystallinity of cellulose type I of 64%. The methods for measuring the degree of carboxymethyl substitution and the crystallinity of cellulose type I are as described above.
The resulting sodium salt of carboxymethyl cellulose was dispersed in water to form a 1% (w/v) aqueous dispersion. This was then processed three times with a high-pressure homogenizer at 150 MPa to obtain a dispersion of carboxymethyl cellulose nanofibers. The resulting carboxymethyl cellulose nanofibers had an average fiber diameter of 3.2 nm and an aspect ratio of 40.
The obtained carboxymethylated cellulose nanofibers were dispersed in water to a solid content of 0.7% by mass, and carboxymethyl cellulose (manufactured by Nippon Paper Industries Co., Ltd., product name: F350HC-4, viscosity (1% by mass, 25°C, 60 rpm) approximately 3000 mPa s, degree of carboxymethyl substitution approximately 0.90) was added in an amount of 40% by mass relative to the carboxymethyl cellulose nanofibers (i.e., so that the solid content of carboxymethyl cellulose was 40 parts by mass when the solid content of the carboxymethyl cellulose nanofibers was 100 parts by mass), and the mixture was stirred for 60 minutes with a TK homomixer (12,000 rpm).
To this dispersion, 0.5% by mass of aqueous sodium hydroxide was added, and the pH was adjusted to 9. The mixture was then applied to the drum surface of a drum dryer D0405 (manufactured by Katsuragi Kogyo Co., Ltd.) and dried at 140°C for 1 minute. The resulting dried product was scraped off and then pulverized using an impact mill at a rate of 10 kg per hour to obtain a dried pulverized product with a moisture content of 5% by mass. The pulverized product was classified using a 30 mesh to obtain a powder containing carboxymethylated cellulose nanofibers and carboxymethyl cellulose (CNF powder).

(Dried udon noodle manufacturing)
100 parts of wheat flour, 1 part of salt, and 1 part of the CNF powder obtained above were placed in a stainless steel beaker and stirred for 5 minutes at 5,000 rpm using a TK homomixer to prepare udon dough. Next, the mixture was rolled out using a noodle roller and noodle strands were prepared according to a prescribed method. These were then dried to a moisture content of approximately 15%, yielding dried udon noodles.
2.5 L of water was added to 200 g of the dried udon noodles, and the noodles were boiled for 13 minutes. The noodles were then drained in a colander and washed with cold water to remove any slime. The noodles were then transferred to a tray, covered with plastic wrap, and stored in a refrigerator.
The udon noodles stored in the refrigerator for 0, 6, 24, and 48 hours were tasted. The tensile strength of each udon was measured using the following method.
・Tasting evaluation:
The texture (ease of swallowing, ease of disintegration) was evaluated on a 10-point scale ranging from excellent (10) to poor (1).
- Measurement of tensile strength:
Using a digital force gauge, a piece of udon was folded in half to form a ring, and a hook-shaped attachment was attached to the measuring part. The attachment was then hooked onto the ring and pulled straight up, measuring the strength at which the udon was torn in two.

[Comparative Example 1]
Dried udon noodles were produced in the same manner as in Example 1, except that no CNF powder was added, and the tasting and tensile strength were measured.

The taste evaluation results for the udon noodles of Example 1 and Comparative Example 1 are shown in Table 1, and the tensile strength is shown in Table 2.

As shown in Table 1, the udon noodles of Example 1 showed a slower deterioration in texture over time when stored in a freezer after boiling than the udon noodles of Comparative Example 1. Furthermore, as shown in Table 2, the tensile strength also showed a slower deterioration over time.

Claims (3)

Carboxymethylated cellulose nanofibers;
A dried noodle containing carboxymethyl cellulose or a salt thereof having a degree of carboxymethyl group substitution per anhydroglucose unit of 0.65 to 1.1, and cereal flour,
The dried noodles contain the carboxymethyl cellulose and its salt in an amount ranging from 25 to 60% by mass relative to the cellulose nanofiber (bone dry solid content). The dried noodles according to claim 1 , wherein the carboxymethylated cellulose nanofibers have a degree of carboxymethyl substitution in the range of 0.01 to 0.50. The dried noodles according to any one of claims 1 and 2, wherein the dried noodles are one type selected from the group consisting of udon, soba, somen, hiyamugi, Chinese noodles, yakisoba, macaroni, spaghetti, pasta, Korean hiyashi noodles, kuzukiri, harusame, rice vermicelli, gyoza wrappers, shumai wrappers, and wontons.