Bread products

Abstract

To provide bread products containing rice flour that are voluminous, exhibit excellent resilience, suppress the formation of large air bubbles, and possess an excellent texture.SOLUTION: Bread products comprise cereal flours containing cellulose nanofibers, hydroxypropyl methylcellulose, and rice flour. The bread products contain 0.05 to 5 mass% of the cellulose nanofibers on the basis of the absolute dry mass of the cereal flours. Furthermore, the cellulose nanofibers are anionically modified cellulose nanofibers.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to breads containing cellulose nanofibers, hydroxypropyl methylcellulose, and rice flour. [Background technology]

[0002] Generally, breads (bread, pancakes, etc.) are produced by mixing, fermenting, shaping, final fermentation, and heating using wheat flour (including starch and gluten) and other grain flours as the main ingredient, along with water, foaming agents (yeast, baking soda, etc.), salt, eggs, oils, and other ingredients. The properties required for such breads include volume, a uniform appearance, and fine, uniform bubbles in the inner phase (the cut surface when the bread is cut). Importantly, the texture must also remain moist even over time, be crisp, and melt in the mouth. Known methods for improving this include using wheat flour with a high gluten content to increase water absorption, and using large amounts of sugars, oils, eggs, emulsifiers, etc. Patent Document 1 also discloses a method of adding carboxymethylcellulose or a salt thereof, which has a carboxymethyl substitution degree per anhydroglucose unit within a specific range.

[0003] Furthermore, rice flour bread, in which wheat flour is substituted with rice flour, has been proposed for consumers with wheat allergies, but the reduced gluten content reduces the extensibility of the bread dough, resulting in insufficient retention of carbon dioxide gas generated during yeast fermentation, reducing the number of air bubbles in the bread and resulting in a poor texture. Therefore, Patent Document 2 discloses a method of adding hydroxypropyl methylcellulose to breads primarily made from rice flour to improve the volume, shape retention, and texture. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-226983 [Patent Document 2] Patent No. 6942643 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when wheat flour is partially replaced with rice flour, the gluten content decreases, resulting in a decrease in dough extensibility, which in turn results in insufficient retention of carbon dioxide generated during yeast fermentation, resulting in fewer bubbles in the bread and a poor texture. Hydroxypropyl methylcellulose is effective in retaining carbon dioxide and can improve volume, but tends to produce large bubbles, resulting in a poor texture. Therefore, the present invention aims to provide breads containing rice flour that are voluminous, have excellent resilience, suppress the generation of large bubbles, and have a good dough texture. [Means for solving the problem]

[0006] As a result of extensive research to achieve this object, the present inventors discovered that blending cellulose nanofiber (CNF) and hydroxypropyl methylcellulose (HPMC) is effective, and thus completed the present invention.

[0007] The present invention provides the following: (1) Breads containing cellulose nanofibers, hydroxypropyl methylcellulose, and rice flour, wherein the cellulose nanofibers are present in an amount of 0.05 to 5% by mass relative to the bone dry mass of the flour. (2) The bread according to (2), wherein the cellulose nanofibers are anion-modified cellulose nanofibers. (3) Bread 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 bread according to (3), wherein the anion-modified cellulose nanofiber is a carboxymethylated cellulose nanofiber having a degree of carboxymethyl substitution in the range of 0.01 to 0.50. (5) Breads according to (1) or (2), characterized in that they contain cellulose nanofibers in the range of 0.1 to 1% by mass and hydroxypropyl methylcellulose in the range of 1 to 3% by mass, based on the bone dry mass of the flour. (6) Breads according to (1) or (2), further containing carboxymethyl cellulose. (7) Breads according to (1) or (2), containing rice flour in an amount of 5 to 95% by mass based on the bone dry mass of the total grain flour. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide rice flour-containing breads that are voluminous, have excellent resilience, and further have a good dough texture with the generation of large air bubbles suppressed. DETAILED DESCRIPTION OF THE INVENTION

[0009] The breads of the present invention will be described below. In the present invention, the symbol "to" includes both ends. That is, "X to Y" includes both the values ​​X and Y at both ends.

[0010] The breads of the present invention contain rice flour, cellulose nanofibers, and hydroxypropyl methylcellulose, and contain the cellulose nanofibers in an amount of 0.05% by mass or more and 5% by mass or less relative to the bone dry mass of the flour.

[0011] (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

[0012] 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 or other carboxyalkyl group-containing cellulose, anionically modified cellulose such as phosphate ester group-introduced cellulose, 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.

[0013] (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, and pulp), animal materials (e.g., sea squirts), algae, and microorganisms (e.g., acetic acid bacteria (Acetobacter)). Pulp includes 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. While all of these can be used, cellulose fibers derived from plants or microorganisms are preferred, and plant-derived cellulose fibers are more preferred.

[0014] (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.

[0015] <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 of cellulose type I crystals can be observed.

[0016] <Crystallization 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. There is no particular upper limit to the degree of crystallinity of type I cellulose. In practice, the upper limit is thought to be approximately 90%.

[0017] The method for measuring the crystallinity of cellulose type I of carboxymethylated cellulose nanofibers is as follows: The sample was placed in a glass cell and measured using an X-ray diffraction measurement device (LabX XRD-6000, Shimadzu Corporation). The crystallinity was calculated using the method of Segal et al., where the diffraction intensity at 2θ = 10° to 30° in the X-ray diffraction pattern was used as the baseline, and the crystallinity was calculated using 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.

[0018] 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 part.

[0019] The proportion of type I crystals in carboxymethylated cellulose nanofibers is usually the same as that in the carboxymethyl cellulose before being made into nanofibers.

[0020] <Carboxymethyl substitution degree> 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 fibrous 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 degree of 0.20 to 0.40 and a cellulose type I crystallinity of 60% or more. The carboxymethyl substitution degree 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.

[0021] In the present invention, anhydroglucose unit refers to each anhydroglucose (glucose residue) that constitutes cellulose. 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 constitute 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.

[0022] The degree of carboxymethyl substitution is measured as follows: Weigh out approximately 2.0 g of sample and place it in a 300 mL Erlenmeyer flask with a stopper. Add 100 mL of a solution of 1000 mL of nitric acid methanol and 100 mL of special-grade concentrated nitric acid, and shake for 3 hours to convert the carboxymethylated cellulose nanofiber salt (CMC) into H-CMC (hydrogen-type carboxymethylated cellulose nanofiber). Weigh out 1.5 to 2.0 g of the bone-dry H-CMC and place it in a 300 mL Erlenmeyer flask with a stopper. Wet the H-CMC with 15 mL of 80% methanol, add 100 mL of 0.1 N NaOH, and shake for 3 hours at room temperature. Using phenolphthalein as an indicator, back-titrate the excess NaOH with 0.1 N H2SO4, and calculate the degree of carboxymethyl substitution (DS value) using the following formula: A=[(100×F'-0.1N-H2SO4(mL)×F)×0.1] / (H-CMC Absolute dry mass (g) Carboxymethyl substitution degree = 0.162 x A / (1 - 0.058 x A) F': Factor of 0.1N-H2SO4 F: Factor of 0.1N NaOH.

[0023] The degree of carboxymethyl substitution in the carboxymethylated cellulose nanofibers is usually the same as the degree of carboxymethyl substitution in the carboxymethylated cellulose before being made into nanofibers.

[0024] <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.

[0025] The aspect ratio of the carboxymethylated cellulose nanofiber 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 it suitable for use as an additive. Furthermore, its high fluidity makes it 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 the carboxymethylated cellulose nanofiber can be controlled by the mixing ratio of solvent and water during carboxymethylation, the amount of chemicals added, and the degree of carboxymethylation. Furthermore, carboxymethylated cellulose nanofibers can be produced, for example, by the production method described below.

[0026] 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.

[0027] (Method of producing carboxymethylated cellulose nanofibers) The carboxymethylated cellulose nanofibers used in the present invention are not particularly limited, but can be produced by defibrating carboxymethylated cellulose produced by the following method.

[0028] 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). Carboxymethylated cellulose capable of forming nanofibers having the above-mentioned characteristics of the present invention can be produced by carrying out mercerization (alkali treatment of cellulose) in a solvent mainly composed of water, followed by carboxymethylation (also called etherification) in a mixed solvent of water and an organic solvent.

[0029] (cellulose) In the present invention, cellulose refers to a polysaccharide having a structure in which D-glucopyranose (also simply referred to as "glucose residues" or "anhydroglucose") units are linked together via β-1,4 bonds. Cellulose is generally classified into native cellulose, regenerated cellulose, fine cellulose, microcrystalline cellulose (a cellulose derived from excluding amorphous regions), etc., based on its origin and production method. In the present invention, any of these celluloses can be used as a raw material for mercerized cellulose. However, in order to maintain a crystallinity of cellulose type I of preferably 40% or more in the carboxymethylated cellulose nanofibers, it is preferable to use cellulose with a high degree of crystallinity of cellulose type I as the raw material. The crystallinity of cellulose type I of the raw cellulose is preferably 70% or more, more preferably 80% or more. The method for measuring the crystallinity of cellulose type I is as described above.

[0030] Examples of natural cellulose include bleached pulp or unbleached pulp (bleached wood pulp or unbleached wood pulp); linters, purified linters; and cellulose produced by microorganisms such as acetic acid bacteria. The raw materials for bleached pulp or unbleached pulp are not particularly limited, and examples include wood, cotton, straw, bamboo, hemp, jute, and kenaf. 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 by 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)). In addition to papermaking pulp, dissolving pulp may also be used. Dissolving pulp is chemically refined pulp that is primarily dissolved in chemicals before use and is the main raw material for artificial fibers, cellophane, etc.

[0031] Examples of regenerated cellulose include cellulose dissolved in a certain solvent such as a cuprammonium solution, a cellulose xanthate solution, or a morpholine derivative, and then spun again.

[0032] Examples of fine cellulose include those obtained by depolymerizing cellulosic materials, including the above-mentioned natural cellulose and regenerated cellulose (e.g., acid hydrolysis, alkaline hydrolysis, enzymatic decomposition, crushing treatment, vibrating ball mill treatment, etc.), and those obtained by mechanically treating the above-mentioned cellulosic materials.

[0033] (mercerization) Mercerized cellulose (also called alkali cellulose) is obtained by using the above-mentioned cellulose as a raw material and adding a mercerizing agent (alkali).

[0034] A solvent that primarily uses water (a solvent primarily composed of water) refers to a solvent that contains water at a ratio of more than 50% by mass. The water content in a solvent primarily composed of water 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. A particularly preferred solvent primarily composed of water is 100% by mass (i.e., water).

[0035] Examples of solvents other than water (used in a mixture with water) in a water-based solvent include organic solvents used as solvents in the subsequent carboxymethylation step. Examples 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; and dioxane, diethyl ether, benzene, and dichloromethane. These solvents, alone or in combination, can be added to water in an amount of less than 50% by mass to be used as solvents in the mercerization step. The content of the organic solvent in a water-based solvent is preferably 45% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, even more preferably 20% by mass or less, even more preferably 10% by mass or less, even more preferably 5% by mass or less, and even more preferably 0% by mass.

[0036] Examples of the mercerizing agent include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide, and any one of these can be used alone or in combination of two or more. 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 %.

[0037] The amount of mercerizing agent used is not particularly limited, but in one embodiment, it 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.

[0038] The amount of the solvent mainly composed of water during mercerization is preferably 1.5 to 20 times by mass, more preferably 2 to 10 times by mass, relative to the cellulose raw material. By using such an amount, stirring and mixing of the raw material becomes easy, and the reaction can occur uniformly in the raw material.

[0039] The mercerization treatment is carried out by mixing the raw material (cellulose) with a solvent mainly consisting of water, 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, thereby obtaining mercerized cellulose (alkali cellulose).

[0040] The pH during mercerization is preferably 9 or higher, which allows the mercerization reaction to proceed. The pH is more preferably 11 or higher, even more preferably 12 or higher, and may be 13 or higher. There is no particular upper limit to the pH.

[0041] Mercerization can be carried out using a reactor capable of mixing and stirring the above 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 components is preferred from the viewpoints of both uniform mixing and productivity.

[0042] (carboxymethylation) Carboxymethylated cellulose is obtained by adding a carboxymethylating agent (also called an etherifying agent) to mercerized cellulose.

[0043] 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.

[0044] The amount of carboxymethylating agent used is not particularly limited, but in one embodiment, it is preferably added in the range of 0.5 to 1.5 moles per anhydroglucose unit of cellulose. The lower limit of this range is more preferably 0.6 moles or more, even more preferably 0.7 moles or more, and the upper limit is more preferably 1.3 moles or less, even more preferably 1.1 moles 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 it can be added in the form of an undissolved powder.

[0045] When monochloroacetic acid or sodium monochloroacetate is used as the carboxymethylating agent, the molar ratio of the mercerizing agent to the carboxymethylating agent (mercerizing agent / carboxymethylating agent) is generally set to 0.9 to 2.45. This is because if the ratio is less than 0.9, the carboxymethylation reaction may be insufficient, resulting in unreacted monochloroacetic acid or sodium monochloroacetate remaining and causing waste, and if the ratio is more than 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.

[0046] The concentration of the cellulose raw material in the carboxymethylation reaction is not particularly limited, but is preferably 1 to 40% (w / v).

[0047] 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 the pressure, etc., 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 adding or reducing the organic solvent is not particularly limited as long as it is between the end of the mercerization reaction and immediately after the addition of the carboxymethylating agent, but is preferably within 30 minutes before or after the addition of the carboxymethylating agent, for example.

[0048] Examples of organic 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; and dioxane, diethyl ether, benzene, and dichloromethane. These can be used alone or in combination with water to form a solvent for carboxymethylation. Among these, monohydric alcohols having 1 to 4 carbon atoms are preferred, and monohydric alcohols having 1 to 3 carbon atoms are more preferred, due to their excellent compatibility with water.

[0049] The proportion 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 upper limit of the proportion 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, even more preferably 85% by mass or less, even more preferably 80% by mass or less, and even more preferably 70% by mass or less.

[0050] The reaction medium for carboxymethylation (a cellulose-free mixed solvent of water, organic solvent, etc.) preferably has a lower water content (in other words, a higher organic solvent content) than the reaction medium for mercerization. By satisfying this range, it becomes easier to increase the degree of carboxymethyl substitution while maintaining the crystallinity of the resulting carboxymethylated cellulose. Furthermore, when the reaction medium for carboxymethylation has a lower water content (a higher organic solvent content) than the reaction medium for mercerization, there is also the advantage that, when transitioning from the mercerization reaction to the carboxymethylation reaction, a mixed solvent for the carboxymethylation reaction can be formed by the simple means of adding a desired amount of organic solvent to the reaction system after the mercerization reaction is completed.

[0051] A mixed solvent of water and an organic solvent is prepared, and the carboxymethylating agent is added to the mercerized cellulose. The mixture is stirred 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. Mixing of the liquid containing the mercerized cellulose with the carboxymethylating agent is preferably carried out in multiple batches or by dropwise addition 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 30 to 90°C, preferably 40 to 90°C, more preferably 60 to 80°C, and the etherification (carboxymethylation) reaction is carried out for 30 minutes to 10 hours, preferably 1 to 4 hours, to obtain carboxymethylated cellulose.

[0052] In the carboxymethylation, the reactor used in the mercerization may be used as it is, or a separate reactor may be used which is capable of mixing and stirring the above components while controlling the temperature.

[0053] After the reaction is complete, 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, followed by drying, pulverization, and classification to obtain carboxymethyl cellulose or a salt thereof. When washing to remove by-products, the cellulose may be converted into an acid form beforehand and then returned to the salt form after washing. 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, pearl mills, and the like.

[0054] (defibration into nanofibers) By defibrating the carboxymethyl cellulose obtained by the above method, it can be converted into cellulose nanofibers with nanoscale fiber diameters.

[0055] For defibration, a dispersion of carboxymethyl cellulose obtained by the above method is prepared. Water is preferred as the dispersion medium for ease of handling. Considering the efficiency of defibration and dispersion, the concentration of carboxymethyl cellulose in the dispersion at the time of defibration is preferably 0.01 to 10% (w / v).

[0056] The device used to defibrate carboxymethyl cellulose is not particularly limited, and devices such as high-speed rotation, colloid mill, high-pressure, roll mill, and ultrasonic devices can be used. During defibration, it is preferable to apply a strong shear force to the carboxymethyl cellulose dispersion. For particularly efficient defibration, it is preferable to apply a pressure of 50 MPa or more to the dispersion and to use a wet high-pressure or ultra-high-pressure homogenizer capable of applying a strong shear force. The pressure is more preferably 100 MPa or more, and even more preferably 140 MPa or more. Furthermore, prior to defibration and dispersion treatment with a high-pressure homogenizer, the dispersion may be pretreated, if necessary, using a known mixing, stirring, emulsifying, or dispersing device such as a high-speed shear mixer.

[0057] A high-pressure homogenizer is a device that uses a pump to pressurize (high pressure) a fluid and eject it from an extremely fine gap in the flow path, thereby emulsifying, dispersing, breaking down, pulverizing, and ultra-fine-graining particles through the combined energy of collisions between particles and shear forces caused by pressure differences.

[0058] In the present invention, the carboxymethylated cellulose nanofibers may be used in the form of a dispersion, or may be used as a powder after being dried (to remove the dispersion medium), pulverized, and classified.

[0059] When the carboxymethylated cellulose nanofibers used in the present invention are used as a powder, they may contain other components as necessary. For example, when producing the powder, it is necessary to add a water-soluble polymer to the carboxymethylated cellulose nanofiber dispersion before drying, which improves redispersibility. The reason why the water-soluble polymer improves redispersibility is not clear, but it is presumed that the water-soluble polymer covers the low charge density areas on the surface of the carboxymethylated cellulose nanofiber, suppressing the formation of hydrogen bonds and preventing the nanofibers from aggregating during drying.

[0060] (Water-soluble polymer) When carboxymethylated cellulose nanofibers are used as a powder, examples of water-soluble polymers that can be present during the production of the powder include cellulose derivatives (carboxymethyl cellulose, methyl cellulose, hydroxypropyl cellulose, ethyl cellulose), xanthan gum, xyloglucan, dextrin, dextran, carrageenan, locust bean gum, alginic acid, alginates, pullulan, modified starch (cationized starch, phosphorylated starch, phosphate cross-linked starch, phosphate monoesterified phosphate cross-linked starch, hydroxypropyl starch, hydroxypropylated phosphate cross-linked starch, acetylated adipate cross-linked starch, acetylated phosphate cross-linked starch, acetylated oxidized starch, sodium octenyl succinate starch, acetate starch, oxidized starch), and corn starch. Examples of suitable cellulose nanofibers include gum arabic, locust bean gum, gellan gum, polydextrose, pectin, chitin, water-soluble chitin, chitosan, casein, albumin, soy protein lysate, peptone, polyvinyl alcohol, polyacrylamide, sodium polyacrylate, polyvinylpyrrolidone, polyvinyl acetate, polyamino acids, polylactic acid, polymalic acid, polyglycerin, latex, rosin-based sizing agents, petroleum resin-based sizing agents, urea resin, melamine resin, epoxy resin, polyamide resin, polyamide-polyamine resin, polyethyleneimine, polyamine, vegetable gum, polyethylene oxide, hydrophilic crosslinked polymers, polyacrylates, polyacrylic acid copolymers, tamarind gum, guar gum, and colloidal silica, as well as mixtures of one or more thereof. 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 thought that water-soluble polymers such as carboxymethyl cellulose and its salts penetrate between the carboxymethylated cellulose nanofibers and increase the distance between the nanofibers, thereby improving redispersibility.

[0061] 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 in 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.

[0062] The amount of water-soluble polymer 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, based on the carboxymethylated cellulose nanofiber (bone dry solids). Adding 5% or more by mass of water-soluble polymer improves redispersibility. On the other hand, adding more than 300% by mass of water-soluble polymer can cause problems such as reduced dispersion stability and viscosity characteristics such as thixotropy, which are characteristic of carboxymethylated cellulose nanofiber. Adding 25% or more by mass of water-soluble polymer is preferable because it can achieve particularly excellent redispersibility. Taking thixotropy into consideration, adding 200% or less by mass is also preferable, with 60% or less by mass being particularly preferable.

[0063] (Dry) A dispersion of carboxymethylated cellulose nanofibers, or a dispersion of carboxymethylated cellulose nanofibers optionally mixed with a water-soluble polymer, is dried (to remove the dispersion medium) to obtain a dry solid containing carboxymethylated cellulose nanofibers. In this case, it is preferable to adjust the pH of the dispersion to 9 to 11 before drying, as this improves redispersibility.

[0064] The drying method may be any known method, and is not particularly limited. Examples include spray drying, squeezing, air drying, hot air drying, and vacuum drying. The drying apparatus is not particularly limited, and examples thereof include continuous tunnel dryers, band dryers, vertical dryers, vertical turbo dryers, multi-stage disk dryers, through-flow dryers, rotary dryers, flash dryers, spray dryer dryers, spray dryers, cylindrical dryers, drum dryers, belt dryers, screw conveyor dryers, rotary dryers with heating tubes, vibration transport dryers, batch-type box dryers, through-flow dryers, vacuum box dryers, and agitator dryers, which may be used alone or in combination of two or more.

[0065] Among these, the use of an apparatus for forming a thin film and performing drying is preferred from the viewpoint of energy efficiency, since it can uniformly supply heat energy directly to the material to be dried and can perform the drying process more efficiently and in a short time. An apparatus for forming a thin film and performing drying is also preferred because the dried material can be immediately recovered by a simple means such as scraping off the thin film. It has also been found that when a thin film is formed and then dried, redispersibility is further improved. Examples of apparatus for forming a thin film and performing drying include drum dryers and belt dryers that form a thin film on a drum or belt using a blade or die, and then dry the thin film. The thickness of the thin film when forming and drying a thin film is preferably 50 μm to 1000 μm, and more preferably 100 μm to 300 μm. A thickness of 50 μm or more facilitates scraping after drying, and a thickness of 1000 μm or less further improves redispersibility.

[0066] The residual moisture content after drying is preferably 2% by mass to 15% by mass based on the total dried product.

[0067] (Crushing) The pulverization method is not particularly limited, and known methods can be used, including a dry pulverization method in which the material is treated in a powder state and a wet pulverization method in which the material is treated in a dispersed or dissolved state in a liquid. When wet pulverization is performed, it may be performed before the above-mentioned drying.

[0068] Examples of equipment used in dry grinding include, but are not limited to, cutting mills, impact mills, airflow mills, and media mills. These can be used alone or in combination, and can also be used in several stages using the same model. Of these, airflow mills are preferred. Examples of cutting mills include mesh mills (manufactured by HORAI Co., Ltd.), Atoms (manufactured by Yamamoto Hyakuma Seisakusho Co., Ltd.), knife mills (manufactured by Parman Co., Ltd.), granulators (manufactured by Herbolt Co., Ltd.), and rotary cutter mills (manufactured by Nara Machinery Works Co., Ltd.). Examples of impact mills include Pulperizer (manufactured by Hosokawa Micron Corporation), Fine Impact Mill (manufactured by Hosokawa Micron Corporation), Super Micron Mill (manufactured by Hosokawa Micron Corporation), Sample Mill (manufactured by Seishin Corporation), Bantam Mill (manufactured by Seishin Corporation), Atomizer (manufactured by Seishin Corporation), Tornado Mill (Nikkiso Co., Ltd.), Turbo Mill (Turbo Kogyo Co., Ltd.), and Bevel Impactor (Aikawa Iron Works Co., Ltd.). Examples of airflow mills include CGS-type jet mill (manufactured by Mitsui Mining Co., Ltd.), jet mill (manufactured by Sansho Industry Co., Ltd.), Ebara Jet Micronizer (manufactured by Ebara Corporation), Selenium Miller (manufactured by Masuko Sangyo Co., Ltd.), and supersonic jet mill (manufactured by Nippon Pneumatic Mfg. Co., Ltd.). Examples of media mills include vibration ball mills. Examples of devices used in the wet grinding method include a mass colloider (manufactured by Masuko Sangyo Co., Ltd.), a high-pressure homogenizer (manufactured by Sanmaru Kikai Kogyo Co., Ltd.), and a media mill. An example of a media mill is a bead mill (manufactured by Imex Co., Ltd.).

[0069] (classification) After pulverization, the carboxymethylated cellulose nanofibers are classified to adjust the particle size to a specific value. The classification method is not particularly limited, but can be carried out, for example, by passing the nanofibers through a mesh (sieve) with a predetermined mesh size. The mesh used is preferably 20 to 400 mesh, more preferably 40 to 300 mesh, and even more preferably 60 to 200 mesh, and these may be used in a multi-stage manner. The median diameter of the powder finally obtained is 10.0 to 150.0 μm, preferably 30.0 to 130.0 μm, and even more preferably 50.0 to 120.0 μm.

[0070] In the present invention, the content of cellulose nanofibers is 0.05% by mass or more relative to the bone dry mass of the flour used as the main ingredient of breads in order to achieve a sufficient texture improvement effect, and 5% by mass or less in order to ensure fluidity when kneading the dough, preferably 0.1% by mass or more and 3% by mass or less, more preferably 0.1% by mass or more and 2% by mass or less, and particularly preferably 0.1 to 1.0% by mass.

[0071] (hydroxypropyl methylcellulose) In the present invention, it is essential to contain hydroxypropyl methylcellulose (hereinafter also referred to as HPMC). As the hydroxypropyl methylcellulose, for example, one having a methoxyl group substitution of 10 to 40% by weight and a hydroxyalkyl group substitution of 3 to 30% by weight is preferred, and it is preferable to use low-methoxyl HPMC having a methoxyl group substitution of 19 to 24% by weight and a hydroxyalkyl group substitution of 4 to 12% by weight, or high-methoxyl HPMC having a methoxyl group substitution of 27 to 30% by weight and a hydroxyalkyl group substitution of 4 to 12% by weight.

[0072] Furthermore, the viscosity of a 2 wt% aqueous dispersion of HPMC is preferably 3 mPa·s or more, more preferably 5 mPa·s or more, and even more preferably 50 mPa·s or more. The upper limit is preferably 200,000 mPa·s or less, more preferably 20,000 mPa·s or less, even more preferably 10,000 mPa·s or less, and even more preferably 5,000 mPa·s or less. The amount of hydroxypropyl methylcellulose blended is preferably 1 to 3 mass% of the grain, and more preferably 1.5 to 3 mass%.

[0073] (Main raw material) In the present invention, it is essential that rice flour be included as the main raw material flour. The rice flour content is preferably 50 to 95% by mass of the total bone dry mass of all cereal flours and starch. Rice flour is typically produced by polishing and grinding raw non-glutinous rice. Examples of non-glutinous rice include Japonica rice, Indica rice, and Javanica rice. Examples of rice to be ground include polished rice, brown rice, broken rice, and old rice. There are no particular limitations on the particle size after grinding, and it is typically about the same as the particle size of commonly available joshinko rice flour.

[0074] In addition to these ordinary rice flours, so-called pregelatinized rice flour, which is obtained by subjecting non-glutinous rice or glutinous rice to rice cooking or mechanical treatment to decrystallize the starch contained in the rice and pulverizing it into powder, can also be used in combination.

[0075] The breads of the present invention must contain rice flour as the grain flour (main ingredient), but may contain other grain flours such as wheat flour. They also refer to breads made by fermenting and shaping a kneaded dough using water, foaming agents (yeast, baking soda, etc.), salt, sugars, dairy products, egg products, edible oils, etc. as secondary ingredients, followed by baking, steaming, frying, or other heating. Examples of breads include Pullman breads, French breads such as baguettes and batards, rolls such as sweet rolls and table rolls, sweet breads such as croissants, Danish pastries, and yeast donuts, and hotcakes.

[0076] In the present invention, wheat flour normally used in bread making can be used in combination as the cereal flour (main ingredient). Examples of such wheat flour include strong flour, semi-strong flour, medium-strength flour, weak flour, and durum wheat flour. Of these, strong flour, semi-strong flour, and durum wheat flour are preferred. Furthermore, as cereal flour other than wheat flour, rye flour, rye wheat flour, corn flour, soy flour, buckwheat flour, and mixtures thereof can be appropriately selected and used depending on the type of bread desired. These can be used alone or in combination.

[0077] (starch) In the present invention, starch may be added to improve the texture and volume of bread, which are reduced by the addition of rice flour. Examples of starch include corn starch, tapioca starch, potato starch, sweet potato starch, potato starch, arrowroot starch, wheat starch, and rice starch. The starch content is preferably 5 to 50% by mass of the total of the grain flour and starch.

[0078] (auxiliary raw materials) The breads of the present invention may contain secondary ingredients other than the above-mentioned ingredients, as needed. Examples of such secondary ingredients include yeast food; sugars such as sugar, glucose, fructose, invert sugar, starch syrup, maltose, lactose, trehalose, and other oligosaccharides; eggs or egg powder; dairy products such as skim milk powder, whole milk powder, cheese powder, yogurt powder, and whey powder; fats and oils such as shortening, butter, margarine, and other animal and vegetable oils; emulsifiers; leavening agents; thickeners; sweeteners; flavorings; coloring agents; ascorbic acid; inorganic salts such as salt; enzymes such as glucosidase, glucose oxidase, amylase, lipase, and hemicellulase; and dietary fiber.

[0079] The bread of the present invention is produced by baking a dough composition containing the above-mentioned cereal flour, a water component, auxiliary ingredients, and cellulose nanofibers. The dough composition also typically contains a fermented component.

[0080] (Fermented ingredients) The fermentation ingredients are not particularly limited as long as they are those typically used in dough compositions, and examples of the fermentation ingredients include various fermentation ingredients such as sourdough and levain, and yeast (fresh yeast, dry yeast, etc.).

[0081] The fermentation component is preferably contained in an amount of 0.1 to 10% by mass, more preferably 0.5 to 5% by mass, and even more preferably 1 to 5% by mass, relative to 100% by mass of the grain flour.

[0082] (Water component) The water component refers to the total amount of water contained in water, eggs, etc. It is important that the water component is contained in the range of 80 to 150% by mass relative to 100% by mass of flour, preferably 85 to 140% by mass, more preferably 85 to 120% by mass, and even more preferably 90 to 110% by mass. When the water component is 80% by mass or more, bread obtained by heating such a dough composition is soft and has suppressed aging. Furthermore, when the water component is 150% by mass or less, excessive stickiness is suppressed, and workability can be ensured.

[0083] The breads of the present invention preferably contain cellulose nanofibers in an amount of 0.1% by mass or more and 2% by mass or less, more preferably 0.1% by mass or more and 1.5% by mass or less, even more preferably 0.1% by mass or more and 1% by mass or less, and particularly preferably 0.5% by mass or more and 1% by mass or less, relative to the bone dry mass of the flour. With the cellulose nanofiber content within this range, despite the inclusion of soy flour, the breads have a voluminous texture and excellent resilience, and furthermore, all of the textures, including moistness, crispness, and melt-in-the-mouth texture, are improved. The reason why these effects are obtained for the breads of the present invention is not clear, but in the present invention, it is thought that the low shear rate (<0.1 s) of the cellulose nanofibers contained in the breads -1 ) is higher than that of common water-soluble polymers such as carboxymethyl cellulose, which prevents bubbles from coalescing after foaming due to fermentation, preventing the bubbles from collapsing, and thus producing fine bubbles. [Example]

[0084] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0085] (Method for measuring degree of carboxymethyl substitution) 1) Accurately weigh out approximately 2.0 g of carboxymethylated cellulose fiber (bone dry) and place it in a 300 mL Erlenmeyer flask with a stopper. 2) Add 100 mL of a solution of 100 mL of special-grade concentrated nitric acid to 1000 mL of methanol, shake for 3 hours, and convert the carboxymethyl cellulose salt (carboxymethyl cellulose) into hydrogen-type 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 an indicator. 6) The degree of carboxymethyl substitution (DS) is calculated by the following formula: A = [(100 × F' - (0.1N H2SO4) (mL) × F) × 0.1] / (bone-dry mass of hydrogenated carboxymethyl cellulose (g)) DS=0.162×A / (1-0.058×A) A: Amount of 1N NaOH (mL) required to neutralize 1 g of hydrogenated carboxymethyl cellulose F': Factor of 0.1N H2SO4 F: Factor of 0.1N NaOH

[0086] (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

[0087] [Example 1] (Production of carboxymethylated cellulose nanofibers) A 5-L 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 in 121 parts of water. 200 parts of hardwood pulp (LBKP, manufactured by Nippon Paper Industries Co., Ltd.) (dry mass after drying at 100°C for 60 minutes) was then added. The mixture was stirred and mixed at 30°C for 60 minutes to prepare mercerized cellulose. Further stirring was continued, and 117 parts of sodium monochloroacetate was added. 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 and carboxymethylation reactions 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.

[0088] 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 in 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.

[0089] (Production of CNF powder 1) 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 per 100 parts by mass of the solid content of the carboxymethyl cellulose nanofibers), and the mixture was stirred for 60 minutes using a TK homomixer (12,000 rpm).

[0090] To this dispersion, 0.5% by mass of aqueous sodium hydroxide was added to adjust the pH to 9, and then the dispersion was 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 1).

[0091] (Rice flour bread production) Next, rice flour bread was made using a bread maker (product name: Home Bakery SD-MT1, manufactured by Panasonic Corporation) according to the method described below. (1) The raw materials were weighed as shown in Table 1. The raw material values ​​in Table 1 represent parts by mass. (2) Put the ingredients into a bread machine and mix well until the dough is combined. (Add water, butter, and flour in that order.) The water should be warmed to about 30-40°C. (3) Place the dry yeast into the device. (4) Select the rice flour course (without rice flour) on your bread maker and start. (Rice flour course (without rice flour): Knead → Letting it rest → Add dry yeast → Letting it rest → Knead → Fermentation → Bake (40 minutes) for a total of 1 hour and 55 minutes.) (5) Once cooked, press "Cancel" and remove immediately to let cool. (6) After leaving it for 2 hours, cut the bread in half. (7) Place the cut bread in a Unipack and leave it in a constant temperature room at 25°C for one day. (8) On the day of baking, the stored bread is left to stand for one day and then the following evaluations are carried out.

[0092] The rice flour bread produced in Example 1 was measured and evaluated for the following items. The results are shown in Table 2.

[0093] After baking, the height of the bread is measured. Also, the cross section is observed. ○ (bubble generation is suppressed) △ (some bubbles are observed), The evaluation was made based on the criteria of × (bubbles generated).

[0094] The sliced ​​rice flour bread was taste-tested 3 hours after baking (on the same day) and the next day after baking.

[0095] The hardness and moisture content of the rice flour bread were measured on the day of baking and the day after baking. Hardness was measured by a compression test using a food rheology tester (manufactured by Imada Co., Ltd.). The center of a sliced ​​rice flour bread was pressed 10 mm into the bread using a 2 cm diameter flat probe at a speed of 1 mm / sec, and the stress was recorded as hardness. The weight A of the rice flour bread before drying was measured, and then the weight B of the rice flour bread was measured immediately after drying in a dryer at 105°C for 120 minutes, and the moisture content was calculated using the formula (AB) / A × 100(%).

[0096] [Examples 2 to 5, Comparative Example 1] Rice flour breads of Examples 2 to 5 and Comparative Example 1 were produced and evaluated in the same manner as in Example 1, except that the ingredients were blended as shown in Table 1. The results are shown in Table 2.

[0097] [Table 1] *1: Rice flour for bread "Mizuho Chikara" (manufactured by Tomizawa Shoten)

[0098] [Table 2]

[0099] As is clear from the results in Table 2, rice flour bread containing carboxymethylated cellulose nanofibers and hydroxypropyl methylcellulose suppressed the generation of large bubbles in the inner phase, resulting in a good dough texture, and also exhibited excellent moisture retention (moistness) and texture compared to rice flour bread without carboxymethyl cellulose nanofibers.On the other hand, Example 5, in which the amount of CNF added exceeded 1% by mass relative to the grain flour, was excellent in suppressing bubbles and minimizing the rate of change in hardness, but the height decreased and the volume was slightly inferior.

Claims

1. Breads containing cellulose nanofibers, hydroxypropyl methylcellulose, and rice flour, wherein the breads contain 0.05 to 5% by mass of the cellulose nanofibers relative to the bone dry mass of the flour.

2. The bread according to claim 1, wherein the cellulose nanofibers are anion-modified cellulose nanofibers.

3. 3. The bread according to claim 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 bread according to claim 3, wherein the anion-modified cellulose nanofiber is a carboxymethylated cellulose nanofiber having a degree of carboxymethyl substitution in the range of 0.01 to 0.

50.

5. The bread according to claim 1 or 2, characterized in that it contains 0.1 to 2% by mass of cellulose nanofiber and 1 to 3% by mass of hydroxypropyl methylcellulose relative to the bone dry mass of the flour.

6. 3. The bread according to claim 1, further comprising carboxymethyl cellulose.

7. 3. The bread according to claim 1, wherein the rice flour content is 5 to 95% by mass based on the bone dry mass of the total grain flour.

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