Dough composition and bakery food composition

Abstract

To provide a dough composition capable of obtaining a product that is excellent in workability, increases swelling, is soft, and inhibits ageing, even when it is highly hydrated.SOLUTION: A dough composition contains 80-150 wt.% of water content and 0.05-5 wt.% of carboxymethylated cellulose nanofiber relative to 100 wt.% of starch-containing cereal powder.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a dough composition and a bakery food composition containing carboxymethylated cellulose nanofibers. [Background technology]

[0002] In the manufacturing process of bread, sponge cake, cookies, donuts, rice crackers, soba noodles, udon noodles, etc., the dough composition is first produced, molded into a certain weight and shape, and then subjected to a heating process such as roasting, frying, or boiling to obtain the finished product.

[0003] It is known that such dough compositions are made by adding water to starch-containing grain flour such as wheat flour containing gliadin and glutenin, and then kneading the mixture to produce gluten, thereby giving the dough compositions their characteristic elasticity and extensibility.

[0004] In particular, in bread and other breads that undergo a fermentation process using yeast, the dough composition expands due to carbon dioxide gas produced by fermentation. The dough composition then expands further when heat is applied, and the gluten network hardens due to thermal denaturation even after baking. Therefore, it is known that the dough can maintain its shape after baking.

[0005] With regard to dough compositions, attempts have been made to increase the amount of water added (hereinafter also referred to as "high hydration") in order to impart softness and moistness to final products such as bread.

[0006] However, simply adding water in excess of the water absorption limit of starch-containing cereal flour such as wheat flour can result in the starch not being able to hydrate, resulting in syneresis, making it difficult to knead the dough composition. Therefore, when adding a large amount of water to a dough composition, a method is used in which the moisture content of the dough is increased by blending ingredients with high water retention properties.

[0007] For example, a method for producing high-hydration bread has been proposed (Patent Document 1), in which konjac flour, starch, and water are formed into a jelly-like solid by a hydration gel reaction between an alkaline coagulant and the glucomannan of the konjac flour, and the resulting tangible water for high-hydration bread, which has been immersed in an acid solution to adjust the pH to a neutral to acidic range, is used as part of the bread-making water mixture. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-320207 Summary of the Invention [Problem to be solved by the invention]

[0009] However, in the method of Patent Document 1, the water retention capacity of konjac flour is insufficient, so the more water is added, the stickier the dough (dough composition) becomes, resulting in poor workability. Furthermore, as a result of the stickiness of the dough, the dough does not hold together well. Furthermore, the bread obtained by baking such dough does not rise sufficiently and is not satisfactory in terms of softness. Furthermore, the product obtained after baking is required to maintain its softness even after several days have passed (suppression of aging).

[0010] Therefore, an object of the present invention is to provide a dough composition that can give a product that is excellent in workability, has improved swelling, is soft, and has inhibited aging, even when a large amount of water is added, and a bakery food composition comprising this dough composition. [Means for solving the problem]

[0011] The present invention provides the following: (1) A dough composition comprising 100% by weight of starch-containing grain powder, 80 to 150% by weight of water, and 0.05 to 5% by weight of carboxymethylated cellulose nanofibers. (2) The dough composition according to (1), wherein the carboxymethylated cellulose nanofiber has a degree of carboxymethyl substitution per anhydroglucose unit of the cellulose nanofiber of 0.01 to 0.50 and a degree of crystallinity of cellulose type I of 40% or more. (3) A dough composition according to (1) or (2), further comprising carboxymethyl cellulose. (4) A dough composition according to any one of (1) to (3), characterized in that the starch-containing grain powder is a mixture of one or more of wheat flour, starches, rice flour, and buckwheat flour. (5) A bakery food composition comprising the dough composition according to any one of (1) to (4). [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a dough composition that can give a product that is excellent in workability, has improved swelling, is soft, and has inhibited aging, even when a large amount of water is added, and a bakery food composition comprising this dough composition. DETAILED DESCRIPTION OF THE INVENTION

[0013] The dough composition of the present invention will be described below. In the present invention, "to" includes the end values. That is, "X to Y" includes the values ​​X and Y at both ends.

[0014] The dough composition of the present invention contains 100% by weight of starch-containing grain powder, 80 to 150% by weight of a water component, and 0.05 to 5% by weight of carboxymethylated cellulose nanofibers.

[0015] (Starch-containing grain powder) In the present invention, any wheat flour typically used in bread making can be used as the starch-containing grain 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, grain flours other than wheat flour include rye flour, rye wheat flour, corn flour, starches, rice flour, buckwheat flour, various starches, and mixtures thereof, which can be appropriately selected and used depending on the type of dough composition of the desired bread or the like.

[0016] These may be used alone or in combination.

[0017] (Fermented ingredients) The fermented ingredients are not particularly limited as long as they are those typically used in dough compositions, and examples of the fermented ingredients include various fermented starters such as sourdough and levain, and yeast (fresh yeast, dry yeast, etc.).

[0018] The fermentation component is preferably contained in an amount of 0.1 to 10% by weight, more preferably 0.5 to 5% by weight, and even more preferably 1 to 5% by weight, relative to 100% by weight of the starch-containing grain powder.

[0019] (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 weight, preferably 80 to 120% by weight, and more preferably 80 to 100% by weight, relative to 100% by weight of the starch-containing grain powder. When the water component is 80% by weight or more, the product obtained by heating such a dough composition is soft and has reduced aging. Furthermore, when the water component is 150% by weight or less, excessive stickiness is suppressed, ensuring workability.

[0020] (Carboxymethylated cellulose nanofiber) Carboxymethylated cellulose nanofibers are nanofibers obtained by converting carboxymethylated cellulose into nanofibers with a nanoscale fiber diameter. Carboxymethylated cellulose has a structure in which some of the hydroxyl groups in the glucose residues that constitute cellulose are ether-bonded to carboxymethyl groups. Carboxymethylated cellulose may take the form of a salt, for example, a metal salt such as sodium carboxymethylated cellulose, and the carboxymethylated cellulose nanofibers may also take the form of a salt.

[0021] (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. A degree of carboxymethyl substitution exceeding 0.50 is believed to dissolve in water and make it impossible to maintain the fiber shape. Furthermore, the degree of carboxymethyl substitution per anhydroglucose unit of cellulose is preferably 0.01 or more. A degree of carboxymethyl substitution less than 0.01 is believed to require a large amount of energy to defibrate into carboxymethylated cellulose nanofibers. From the viewpoint of operability, the degree of substitution is more preferably 0.02 to 0.50, even more preferably 0.05 to 0.50, and even more preferably 0.10 to 0.40. Introducing carboxymethyl groups into cellulose causes electrical repulsion between cellulose molecules, enabling defibration into nanofibers. 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.

[0022] 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.

[0023] The carboxymethylated cellulose nanofibers used in the present invention maintain at least a portion of their fibrous shape even when dispersed in water. That is, when an aqueous dispersion of 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.

[0024] (Crystallization of cellulose type I) The crystallinity of cellulose type I in the carboxymethylated cellulose nanofibers used in the present invention is preferably 40% or more, and more preferably 50% or more. A high crystallinity of cellulose type I, such as 40% or more, results in a high proportion of cellulose that does not dissolve in solvents such as water and maintains its crystalline structure, resulting in high thixotropy and making it suitable for viscosity-adjusting applications such as thickeners. Furthermore, when added to a dough composition, it provides the advantage of improving dough cohesion and workability even with high water content. 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, cellulose type I crystals are likely to be converted to type II. 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 cellulose type I is not particularly limited. A practical upper limit is thought to be approximately 90%.

[0025] 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.

[0026] 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.

[0027] The proportion of type I crystals in the carboxymethylated cellulose nanofibers is usually the same as that in the carboxymethyl cellulose before it is made into nanofibers.

[0028] (fiber diameter, aspect ratio) The carboxymethylated cellulose nanofibers used in the present invention have a nanoscale fiber diameter of 3 nm to 500 nm, preferably 3 nm to 150 nm, more preferably 3 nm to 20 nm, even more preferably 5 nm to 19 nm, and even more preferably 5 nm to 15 nm.

[0029] 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. The lower limit of the aspect ratio is not particularly limited, but is preferably 25 or more, even more preferably 30 or more. When the aspect ratio is 25 or more, the fibrous shape provides the effect of improving thixotropy. 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 having an aspect ratio within the above range can be produced, for example, by the production method described below.

[0030] The average fiber diameter and average fiber length of carboxymethylated 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.

[0031] (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.

[0032] 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.

[0033] (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 factors such as 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, and more preferably 80% or more. The method for measuring the crystallinity of cellulose type I is as described above.

[0034] 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.

[0035] 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. 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.

[0036] (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).

[0037] 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 weight. The water content in a solvent primarily composed of water is preferably 55% by weight or more, more preferably 60% by weight or more, more preferably 70% by weight or more, more preferably 80% by weight or more, even more preferably 90% by weight or more, and even more preferably 95% by weight or more. A particularly preferred solvent primarily composed of water is 100% by weight (i.e., water).

[0038] The solvent other than water (used in a mixture with water) in the water-based solvent includes the organic solvent used 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 may be used alone or in combination with two or more of these in an amount of less than 50% by weight. The organic solvent content in the water-based solvent is preferably 45% by weight or less, more preferably 40% by weight or less, even more preferably 30% by weight or less, even more preferably 20% by weight or less, even more preferably 10% by weight or less, even more preferably 5% by weight or less, and even more preferably 0% by weight.

[0039] 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 wt %, preferably 2 to 45 wt %, and more preferably 3 to 25 wt %.

[0040] 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.

[0041] The amount of the solvent mainly composed of water during mercerization is preferably 1.5 to 20 times by weight, more preferably 2 to 10 times by weight, relative to the cellulose raw material. By using such an amount, the raw material can be easily stirred and mixed, and the reaction can occur uniformly in the raw material.

[0042] 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).

[0043] 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.

[0044] 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.

[0045] (carboxymethylation) Carboxymethylated cellulose is obtained by adding a carboxymethylating agent (also called an etherifying agent) to mercerized cellulose.

[0046] 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.

[0047] 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 wt % aqueous solution, more preferably 30 to 60 wt %, but is not limited thereto, or it can be added in the form of an undissolved powder.

[0048] 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.

[0049] The concentration of the cellulose raw material in the carboxymethylation reaction is not particularly limited, but is preferably 1 to 40% (w / v).

[0050] 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.

[0051] 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.

[0052] The proportion of organic solvent in the mixed solvent during carboxymethylation is preferably 20% by weight or more, more preferably 30% by weight or more, even more preferably 40% by weight or more, even more preferably 45% by weight or more, and particularly preferably 50% by weight or more, based on the total weight of water and organic solvent. The upper limit of the proportion of organic solvent is not limited and may be, for example, 99% by weight or less. Considering the cost of the organic solvent to be added, the proportion is preferably 90% by weight or less, even more preferably 85% by weight or less, even more preferably 80% by weight or less, and even more preferably 70% by weight or less.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] (defibration into nanofibers) By defibrating the carboxymethylated cellulose obtained by the above method, it can be converted into cellulose nanofibers with nanoscale fiber diameters.

[0058] 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).

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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 preferable to add a water-soluble polymer to the carboxymethylated cellulose nanofiber dispersion before drying, as this 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.

[0063] (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, starch, potato starch, arrowroot flour, 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), cocoa, and the like. Examples of suitable cellulose nanofibers include starch, 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, starch-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.

[0064] 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 wt% 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.

[0065] The amount of water-soluble polymer is preferably 5% to 300% by weight, more preferably 20% to 300% by weight, even more preferably 25% to 200% by weight, and even more preferably 25% to 60% by weight, based on the carboxymethylated cellulose nanofiber (bone dry solids). Adding 5% or more by weight of water-soluble polymer improves redispersibility. On the other hand, adding more than 300% by weight of water-soluble polymer can cause problems such as reduced viscosity characteristics, such as thixotropy, which is a characteristic of carboxymethylated cellulose nanofiber, and reduced dispersion stability. Adding 25% or more by weight of water-soluble polymer is preferable because it can achieve particularly excellent redispersibility. Taking thixotropy into consideration, adding 200% or less by weight is also preferable, with 60% or less by weight being particularly preferable.

[0066] (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.

[0067] 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.

[0068] 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.

[0069] The residual moisture content after drying is preferably 2% by weight to 15% by weight based on the total dried product.

[0070] (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.

[0071] 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.).

[0072] (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 μm to 150.0 μm, preferably 30.0 μm to 130.0 μm, and even more preferably 50.0 μm to 120.0 μm.

[0073] In the present invention, the content of carboxymethylated cellulose nanofibers is 0.05% by weight or more, based on the bone dry weight of the starch-containing grain powder, from the viewpoint of obtaining a sufficient swelling-improving effect on the product obtained by heating, even when a large amount of water is added, and is 5% by weight or less, preferably 0.1 to 3% by weight, and more preferably 0.2 to 2% by weight, from the viewpoint of the workability, moldability, and hardness of the dough composition.

[0074] (auxiliary raw materials) The dough composition of the present invention may contain auxiliary ingredients other than the above-mentioned raw ingredients, as necessary. Examples of such auxiliary ingredients include yeast food; sugars such as sugar, glucose, fructose, invert sugar, starch syrup, maltose, lactose, and 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.

[0075] (Embodiment) The dough composition of the present invention can be used for bakery food compositions such as bread, sponge cake, cookies, donuts, etc.; noodles such as soba, udon, pasta, somen, ramen, etc.; ingredients for Chinese cuisine such as spring roll wrappers, gyoza wrappers, and Xiaolongbao wrappers; rice crackers, etc. Among these, it is preferable to use it as a bakery food composition, in view of the effects of being able to obtain products that are excellent in workability (good dough cohesion) even with a high water content and that are soft and have inhibited aging after baking.

[0076] The bakery food composition of the present invention comprises the dough composition of the present invention. More specifically, the bakery food composition is obtained by adding a water component and a dispersion liquid containing carboxymethylated cellulose nanofibers to a mixture containing starch-containing grain powder and secondary ingredients such as sugar, fermentation ingredients, oils and fats, skim milk powder, salt, and oligosaccharides added as needed, and stirring the mixture until homogeneous to form a dough (dough composition), followed by fermentation and baking. Note that the method for producing the bakery food composition is not limited to this and may be modified as appropriate.

[0077] The dough composition of the present invention contains 100% by weight of starch-containing grain powder, 80 to 150% by weight of water, and 0.05 to 5% by weight of carboxymethylated cellulose nanofibers, so this dough composition is well-formed, and products obtained using it have excellent rise, and further, due to the increased moisture content, they are soft and aging (hardening) is inhibited. [Example]

[0078] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0079] (Method for measuring degree of carboxymethyl substitution) 1) Approximately 2.0 g of carboxymethylated cellulose fiber (bone dry) was weighed out and placed in a 300 mL Erlenmeyer flask with a stopper. 2) 100 mL of a solution of 1000 mL of nitric acid methanol and 100 mL of special-grade concentrated nitric acid was added, and the mixture was shaken for 3 hours to convert the carboxymethyl cellulose salt (carboxymethyl cellulose) into hydrogen-type carboxymethyl cellulose. 3) 1.5 to 2.0 g of hydrogenated carboxymethyl cellulose (bone dry) was precisely weighed and placed in a 300 mL Erlenmeyer flask with a stopper. 4) The hydrogenated carboxymethyl cellulose was wetted with 15 mL of 80% methanol, and 100 mL of 0.1 N NaOH was added, followed by shaking at room temperature for 3 hours. 5) Excess NaOH was back-titrated with 0.1N H2SO4 using phenolphthalein as an indicator. 6) The degree of carboxymethyl substitution (DS) was calculated by the following formula: A = [(100 × F' - (0.1N H2SO4) (mL) × F) × 0.1] / (bone-dry weight 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

[0080] (Method for measuring average fiber diameter and aspect ratio) The average fiber diameter and average fiber length of cellulose nanofibers 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

[0081] (Production 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 weight, after drying at 100°C for 60 minutes) were then added. The mixture was stirred and mixed at 30°C for 60 minutes to prepare mercerized cellulose. 117 parts of sodium monochloroacetate was added with further 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 water content of the reaction medium during the mercerization and carboxymethylation reactions was 10 wt%. After the reaction was completed, 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.

[0082] 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.

[0083] (Production of CNF powder 1) The obtained carboxymethylated cellulose nanofibers were dispersed in water to a solid content of 0.7 wt %, and carboxymethyl cellulose (manufactured by Nippon Paper Industries Co., Ltd., product name: F350HC-4, viscosity (1 wt %, 25°C, 60 rpm) approximately 3000 mPa·s, degree of carboxymethyl substitution approximately 0.90) was added in an amount of 40 wt % relative to the carboxymethyl cellulose nanofibers (i.e., so that the solid content of carboxymethyl cellulose was 40 wt parts per 100 wt parts of the solid content of the carboxymethyl cellulose nanofibers), and the mixture was stirred for 60 minutes using a TK homomixer (12,000 rpm).

[0084] To this dispersion, 0.5 wt% aqueous sodium hydroxide solution 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 wt%. The pulverized product was classified using a 30 mesh to obtain a powder containing carboxymethylated cellulose nanofibers and carboxymethyl cellulose (CNF powder 1).

[0085] (Examples 1 to 3, Comparative Examples 1 to 5) (Bread production) When CNF powder 1 was included among the ingredients in Table 1, a CNF dispersion was prepared by stirring CNF powder 1 and water for 30 minutes at 3,000 rpm using a homodisper. Next, the ingredients in Table 1 other than CNF powder 1 and water were added to a bread maker together with the prepared CNF dispersion (or water). Next, the bread maker was set to the bread course (a total of 4 hours of kneading, resting, fermentation, and baking) to produce bread. In Comparative Example 5, carboxymethyl cellulose (manufactured by Nippon Paper Industries Co., Ltd., SLD-F1) was used in place of CNF powder 1. The numerical values ​​of the raw materials in Table 1 represent parts by weight.

[0086] (evaluation) (Workability during bread making) In the Examples and Comparative Examples, the inside of the bread machine was visually inspected after the kneading step, and the state of the dough was evaluated according to the following criteria. ○: The dough holds together well when kneaded, is not sticky, does not stick to the container, and is easy to work with. △: The dough holds together well when kneaded, but is sticky and sticks to the container, but this does not cause any problems in use. ×: The dough was not sufficiently united when kneaded, was sticky, and adhered to the container, making it difficult to work with.

[0087] (Bread evaluation) The bread obtained in the Examples and Comparative Examples was allowed to cool at room temperature for 2 hours after production, and then cut into test pieces 20 mm thick from the center with a bread knife, which were used for the following measurements.

[0088] (height) The test pieces were measured from the bottom to the top of the bread using a ruler, and the results are shown in Table 1. A higher height indicates improved rise.

[0089] (Moisture percentage) The inner phase of the test specimens, which had been left standing at room temperature (25°C / 50%), was cut into 1 cm squares and their weights (WA) were measured. The 1 cm square test specimens were then dried in a dryer at 105°C for 3 hours, and their weights (WB) after drying were measured. The moisture content was calculated from (WA - WB) / WA x 100. The results are shown in Table 1. The moisture content of the test specimens on the day of firing is shown in the "Moisture Content (Day 0)" column, and the moisture content of the test specimens stored in a zippered vinyl bag in a thermostatic chamber at 25°C for 3 days after production is shown in the "Moisture Content (Day 3)" column. The change in moisture content between the moisture content after 3 days and the moisture content on the day of firing was calculated and shown in the "ΔMoisture Content" column. In the present invention, the closer the ΔMoisture Content is to 0, the more drying is suppressed.

[0090] (Hardness) The hardness of the test pieces was measured using a rheometer (Food Rheology Tester FRTS-50N, manufactured by Imada). Specifically, a plunger with a diameter of 2.0 cm was used, and the value was recorded when the plunger was pushed 1 cm at a plunge speed of 1 mm / sec. Measurements were taken at five or more points, and the average value was calculated. The results are shown in Table 1. The hardness of the test pieces on the day of baking is shown in the "Hardness (0 days)" column, and the hardness of the test pieces stored in a zippered vinyl bag in a constant temperature room at 25°C for three days after production is shown in the "Hardness (3 days)" column. The smaller the value, the softer the bread of the test piece. Furthermore, the change in hardness after three days and the hardness on the day of baking was measured, and this is shown in the "ΔHardness" column. The smaller the value, the more suppressed staling. In the present invention, a ΔHardness of less than 5 can be said to be suppressed staling.

[0091] [Table 1]

[0092] As is clear from the results in Table 1, the dough compositions of Examples 1 to 3, which contain 100% by weight of starch-containing grain powder, 80 to 150% by weight of water, and 0.05 to 5% by weight of carboxymethylated cellulose nanofibers, have good dough cohesion and workability even when the amount of water added is increased, and the bread obtained using this dough composition has improved rise, and although it contains a high amount of water, the Δ moisture content is close to 0, preventing drying, and the Δ hardness is less than 5, which means that it is soft and aging is inhibited.

Claims

1. A dough composition comprising 100% by weight of one or more types of wheat flour selected from the group consisting of strong wheat flour, semi-strong wheat flour, medium wheat flour, soft wheat flour, and durum wheat flour, 80 to 150% by weight of water, and 0.05 to 5% by weight of carboxymethylated cellulose nanofibers, The dough composition further contains 25 to 60% by weight of carboxymethyl cellulose or a salt thereof relative to the carboxymethylated cellulose nanofibers, The carboxymethyl cellulose or salt thereof has a degree of carboxymethyl substitution per anhydroglucose unit in the range of 0.55 to 1.6, The dough composition is characterized in that the Brookfield viscosity of a 1 wt % aqueous solution of the carboxymethyl cellulose or a salt thereof at 25°C and 60 rpm is in the range of 1,000 to 8,000 mPa·s.

2. The carboxymethylated cellulose nanofiber has a degree of carboxymethyl substitution per anhydroglucose unit of the cellulose nanofiber of 0.01 to 0.50 and a crystallinity of cellulose type I of 40% or more.

3. A bakery food composition comprising the dough composition according to claim 1 or 2.

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