Pancake dough using rice flour and method for producing pancake

Abstract

To obtain pancake dough using rice flour, the dough having sufficient rise, good texture, and no problem in appearance by using fine cellulose fibers.SOLUTION: Egg yolk and gluten-free pancake dough contains rice flour and cellulose fine fibers, the cellulose fine fibers being carboxymethylated and being cellulose nanofibers.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a pancake batter using rice flour and a method for producing a pancake using the same.

Background Art

[0002] Rice flour has been widely used since ancient times in the production of Japanese confectionery such as steamed buns, dumplings, rice cakes, and senbei. In recent years, in pursuit of a chewy texture and as an alternative to wheat flour, which can cause allergies, the development of Western confectionery using rice flour has also been considered, and it is expected to be applied to confectionery such as hot cakes and pancakes.

[0003] On the other hand, unlike wheat flour, rice flour does not contain gluten. Therefore, even if a somewhat chewy texture is imparted, there are problems such as stickiness in the batter, insufficient swelling of the batter, resulting in insufficient thickness, easy crumbling and poor appearance, and a tendency to have a soggy texture.

[0004] To address such problems, for example, Patent Document 1 proposed using special rice flour, and Patent Document 2 proposed using konjac flour in combination.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

[0006] However, in Patent Document 1, there are concerns about raw material supply because special rice flour is required, and in Patent Document 2, a unique flavor is generated because konjac flour is used, and there is also a concern that the batter becomes too firm.

Summary of the Invention

Problems to be Solved by the Invention

[0007] Therefore, the present inventors have found that by using microcrystalline cellulose fibers, it is possible to obtain a pancake batter using rice flour that has sufficient puffiness, good texture, and no problems with appearance, and have thus completed the present invention.

[0008] That is, the present invention is as follows (1) to (6). (1) A pancake batter characterized by containing rice flour and cellulose microfibers. (2) The pancake batter according to (1), characterized by not containing egg yolk. (3) The pancake batter according to any one of (1) to (2), characterized by not containing gluten. (4) The pancake batter according to any one of (1) to (2), characterized in that the cellulose microfibers are carboxymethylated. (5) The pancake batter according to any one of (1) to (2), characterized in that the cellulose microfibers are cellulose nanofibers. (6) A method for producing a pancake, which comprises baking the pancake batter according to any one of (1) to (5).

Advantages of the Invention

[0009] According to the present invention, by using microcrystalline cellulose fibers, it is possible to obtain a pancake batter using rice flour that has sufficient puffiness, good texture, and no problems with appearance.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0011] The present invention will be described in detail below. In the present invention, "~" includes the end values. That is, "X~Y" includes the values X and Y at both ends thereof.

[0012] The present invention is a pancake batter characterized by containing rice flour and microcrystalline cellulose fibers.

[0013] <rice flour> In the present invention, it is essential to contain rice flour as the cereal flour of the main raw material. The rice flour is preferably contained in an amount of 50 to 95% by mass based on the total absolute dry mass of all cereal flours and starch. Rice flour is usually obtained by polishing raw polished rice and pulverizing it into a powder. Examples of polished rice include japonica rice, indica rice, and javanica rice. Examples of the rice for pulverization include polished rice, brown rice, broken rice, and old rice. The particle size after pulverization is not particularly limited and is usually about the particle size of newly produced flour generally commercially available.

[0014] In the present invention, in addition to rice flour as the cereal flour (main raw material), cereal flours such as wheat flour may be contained as necessary. Cereal flours other than rice flour include wheat flours (strong flour, semi-strong flour, medium flour, weak flour, durum wheat flour, whole grain flour, etc.), buckwheat flour, soybean flour, etc. In addition, untreated starches such as potato starch, sweet potato starch, tapioca starch, corn starch, waxy corn starch, rice starch, mung bean starch, etc. and processed starches produced by subjecting the untreated starch to etherification, esterification, oxidation, bleaching, crosslinking, alpha modification, etc. alone or in combination thereof can be used. However, the presence of cereal flours other than rice flour may raise concerns about the onset of allergies. Since the pancake batter of the present invention can obtain excellent batter swelling and texture even with only rice flour by using microcrystalline cellulose, it is preferably free from the admixture of cereal flours other than rice flour, and particularly preferably free from gluten.

[0015] <Other materials> In addition, sodium chloride and brine may be blended as additives. In addition to these, thickening stabilizers such as phosphates, alginic acids (alginates and alginate esters), caproic gum, guar gum, tamarind seed gum, pectin, xanthan gum, carrageenan, curdlan, emulsifiers, fats and oils, egg white, milk protein, coloring agents, antioxidants, wheat protein, and other components having physiological activities, such as vitamin agents, calcium, iron, and other seasonings, can also be used as desired.

[0016] On the other hand, since heat does not participate in the gelling action of alginic acids and they have heat-irreversible gel properties, there is a concern that workability may deteriorate depending on the formulation. In the present invention, since an appropriate thickening action can be obtained with microcrystalline cellulose fibers, the workability is good, and it is desirable not to contain alginic acids.

[0017] In addition, in the pancake batter of the present invention, it is preferable not to contain egg yolk or egg white. Although egg yolk or egg white is usually used in pancake batter, in the present invention, due to the presence of microcrystalline cellulose fibers, excellent batter swelling and texture can be obtained even with only rice flour, so it is preferable not to contain egg yolk or egg white, which may cause allergic reactions.

[0018] <Cellulose microfibers> The cellulose microfibers used in the present invention are microfibers made from cellulose as a raw material. The average fiber diameter of the cellulose microfibers is not particularly limited, but is about 2 nm to 10 μm. The cellulose microfibers may be, for example, microfibrillated cellulose (also referred to as MFC) defibrated to have an average fiber diameter of about 1 μm to 10 μm, preferably about 3 μm to 7 μm. Alternatively, they may be cellulose nanofibers (also referred to as CNF) finely defibrated to have an average fiber diameter of 2 nm to 1 μm, preferably 3 nm to 500 nm, more preferably 3 nm to 100 nm, and even more preferably about 3 nm to 50 nm. The average fiber diameter and average fiber length of the cellulose microfibers can be obtained by appropriately selecting and using a fiber tester manufactured by ABB Ltd., a fractionator manufactured by Valmet, a scanning electron microscope (SEM), an atomic force microscope (AFM), or a transmission electron microscope (TEM) according to the size of the fiber diameter, and averaging the fiber diameter and fiber length obtained from the results of observing each fiber. The cellulose microfibers can be produced by defibrating a cellulose raw material.

[0019] The aspect ratio of the cellulose microfibers used in the present invention is preferably 10 or more, more preferably 15 or more, and even more preferably 20 or more. The upper limit of the aspect ratio is not particularly limited, but is preferably 1000 or less, more preferably 500 or less, and even more preferably 300 or less. The aspect ratio can be calculated by the following formula: Aspect ratio = average fiber length / average fiber diameter

[0020] (Cellulose raw material) The cellulose raw material serving as the raw material for cellulose microfibrils only needs to contain cellulose and is not particularly limited. For example, cellulose raw materials derived from plants (e.g., wood, bamboo, hemp, jute, kenaf, agricultural waste residues, cloth, pulp (softwood unbleached kraft pulp (NUKP), softwood bleached kraft pulp (NBKP), hardwood unbleached kraft pulp (LUKP), hardwood bleached kraft pulp (LBKP), sun-dried kraft pulp (BKP), softwood unbleached sulfite pulp (NUSP), softwood bleached sulfite pulp (NBSP), thermomechanical pulp (TMP), recycled pulp, waste paper, etc.)), cellulose raw materials derived from animals (e.g., tunicates), cellulose raw materials derived from algae, cellulose raw materials derived from microorganisms (e.g., acetic acid bacteria (Acetobacter)), cellulose raw materials derived from microbial products, etc. can be mentioned. As the cellulose raw material, any of these may be used, or a combination of two or more types may be used, but preferably a cellulose raw material derived from a plant or a microorganism, and more preferably a cellulose raw material derived from a plant.

[0021] (Chemical modification) Cellulose has three hydroxyl groups per glucose unit and can undergo various chemical modifications. From the viewpoint of promoting the progress of fibrillation, it is preferable to use chemically modified cellulose microfibrils produced by defibrating a cellulose raw material (chemically modified cellulose) obtained by chemical modification.

[0022] As the chemical modification, anion modification for introducing an anionic group into cellulose is preferable. Specifically, anion modification means introducing an anionic group into the pyranose ring by an oxidation or substitution reaction. In the present invention, the oxidation reaction refers to a reaction of oxidizing the C6 position of the pyranose ring to a carboxyl group. Also, in the present invention, the substitution reaction refers to a reaction of introducing an anionic group into the pyranose ring by a substitution reaction other than the oxidation. Examples of anion modification include oxidation (carboxylation), carboxyalkylation (e.g., carboxymethylation), esterification, etc. Among them, oxidation (carboxylation) and carboxymethylation are more preferable.

[0023] Examples of the chemically modified cellulose microfibrils include TEMPO-oxidized cellulose microfibrils, ozone-oxidized cellulose microfibrils, carboxyalkylated cellulose microfibrils, carboxymethylated cellulose microfibrils, phosphate-esterified cellulose microfibrils, phosphite-esterified cellulose microfibrils, cationized cellulose microfibrils, sulfonated cellulose microfibrils, xanthated cellulose microfibrils, etc. Among them, carboxymethylated cellulose microfibrils are particularly preferred.

[0024] The carboxyalkylated cellulose microfibrils, which are an example of the chemically modified cellulose microfibrils, preferably carboxymethylated cellulose microfibrils, may be obtained by known methods or commercially available products may be used. The degree of carboxyalkyl substitution per anhydrous glucose unit of cellulose is preferably less than 0.60. Further, when the anionic group is a carboxymethyl group, the degree of carboxymethyl substitution is preferably less than 0.60. When the substitution degree is 0.60 or more, the crystallinity decreases and the proportion of the dissolved component increases, so that the function as microfibrils may be lost. The lower limit of the degree of carboxyalkyl substitution is preferably 0.01 or more. Considering the operability, the substitution degree is particularly preferably 0.02 to 0.50, and more preferably 0.10 to 0.40. As an example of a method for producing the carboxyalkylated cellulose fiber as a raw material for such carboxyalkylated cellulose microfibrils, a method including the following steps may be mentioned. The modification is a modification by a substitution reaction. The carboxymethylated cellulose fiber will be described as an example.

[0025] i) A step of mixing a cellulose raw material, a solvent, and a mercerizing agent, and performing a mercerizing treatment at a reaction temperature of 0 to 70°C, preferably 10 to 60°C, and a reaction time of 15 minutes to 8 hours, preferably 30 minutes to 7 hours, and ii) Next, a carboxymethylating agent is added in an amount of 0.05 to 10.0 times the molar amount per glucose residue, and an etherification reaction is carried out at a reaction temperature of 30 to 90°C, preferably 40 to 80°C, and a reaction time of 30 minutes to 10 hours, preferably 1 hour to 4 hours.

[0026] As the solvent during the mercerization and etherification reactions, 3 to 20 times by mass of water or a lower alcohol can be used, specifically, water, methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, isobutanol, tert-butanol, etc. alone, or a mixed medium of two or more of them. When mixing a lower alcohol, the mixing ratio is 60 to 95% by mass. As the mercerizing agent, 0.5 to 20 times the molar amount of an alkali metal hydroxide per anhydrous glucose residue of the cellulose raw material can be used, specifically, sodium hydroxide or potassium hydroxide.

[0027] As described above, the degree of carboxymethyl substitution per glucose unit of cellulose is less than 0.60, and preferably 0.01 or more and less than 0.60. By introducing a carboxymethyl substituent into cellulose, the celluloses repel each other electrically. Therefore, the carboxymethylated cellulose fibers can be easily defibrated. Note that if the carboxymethyl substituent per glucose unit is less than 0.01, defibration may not be sufficient.

[0028] The degree of carboxymethyl substitution of carboxymethylated cellulose fibers can be measured by the following procedure: Precisely weigh about 2.0 g of carboxymethylated cellulose fibers (bone-dry) and place them in a 300 mL conical flask with a stopper. Add 100 mL of a solution prepared by adding 100 mL of special grade concentrated nitric acid to 1000 mL of methanol, shake for 3 hours, and convert the salt-type carboxymethylated (CM) cellulose fibers into hydrogen-type CM cellulose fibers. Precisely weigh 1.5 to 2.0 g of the hydrogen-type CM cellulose fibers (bone-dry) and place them in a 300 mL conical flask with a stopper. Moisten the hydrogen-type CM cellulose fibers with 15 mL of 80% methanol, add 100 mL of 0.1 N NaOH, and shake at room temperature for 3 hours. Using phenolphthalein as an indicator, back-titrate the excess NaOH with 0.1 N H2SO4. Calculate the degree of carboxymethyl substitution (DS) using the following formula. A = [(100×F’ - (0.1 N H2SO4)(mL)×F)×0.1] / (bone-dry mass of hydrogen-type CM cellulose fibers (g)) DS = 0.162×A / (1 - 0.058×A) A: Amount (mL) of 1N NaOH required for neutralization of 1 g of hydrogen-type CM cellulose fiber F’: Factor of 0.1N H2SO4 F: Factor of 0.1N NaOH

[0029] The degree of substitution in carboxymethylated cellulose fiber and that in carboxymethylated cellulose microfiber are usually the same.

[0030] In the carboxyalkylated cellulose fiber obtained in the above process, the carboxyalkyl group introduced into the cellulose raw material is usually in the form of an alkali metal salt such as a sodium salt (this is referred to as the "salt form"). Before the fibrillation step, the alkali metal salt of the carboxyalkylated cellulose fiber may be substituted with other cation salts such as phosphonium salts, imidazolinium salts, ammonium salts, and sulfonium salts. The substitution can be carried out by known methods.

[0031] Cellulose oxide microfiber (also referred to as "carboxylated cellulose microfiber"), which is an example of chemically modified cellulose microfiber, is obtained by oxidizing (carboxylating) the above cellulose raw material by a known method to obtain cellulose oxide fiber and then fibrillation this fiber. As an example of the oxidation (carboxylation) method, a method can be mentioned in which the cellulose raw material is oxidized in water using an oxidizing agent in the presence of an N-oxyl compound and a compound selected from the group consisting of bromides, iodides, and mixtures thereof. By this oxidation reaction, the C6 position of the glucopyranose ring on the cellulose surface is selectively oxidized, and cellulose fiber (TEMPO-oxidized cellulose fiber) having an aldehyde group, a carboxy group (-COOH) or a carboxylate group (-COO―) on the surface is obtained. The TEMPO-oxidized cellulose fiber can be made into TEMPO-oxidized cellulose microfiber by fibrillation by the method described later.

[0032] An N-oxyl compound refers to a compound capable of generating a nitroxyl radical. Any compound can be used as the N-oxyl compound as long as it can promote the target oxidation reaction. For example, 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) and its derivatives (such as 4-hydroxy TEMPO) can be mentioned. The amount of the N-oxyl compound used only needs to be a catalytic amount capable of oxidizing the cellulose raw material and is not particularly limited. For example, for 1 g of absolutely dry cellulose raw material, 0.01 - 10 mmol is preferred, 0.01 - 1 mmol is more preferred, and 0.01 - 0.5 mmol is even more preferred. Also, about 0.1 - 4 mmol / L is suitable for the reaction system.

[0033] A bromide is a compound containing bromine, and examples thereof include alkali metal bromides that can dissociate and ionize in water. Also, an iodide is a compound containing iodine, and examples thereof include alkali metal iodides. The amount of the bromide or iodide used can be selected within a range capable of promoting the oxidation reaction. The total amount of the bromide and iodide is preferably, for example, 0.1 - 100 mmol, more preferably 0.1 - 10 mmol, and even more preferably 0.5 - 5 mmol per 1 g of absolutely dry cellulose raw material.

[0034] As the oxidizing agent, known ones can be used. For example, halogens, hypohalous acids, halous acids, perhalic acids or their salts, halogen oxides, peroxides, etc. can be used. Among them, sodium hypochlorite, which is inexpensive and has a low environmental impact, is preferred. The appropriate amount of the oxidizing agent used is preferably, for example, 0.5 - 500 mmol, more preferably 0.5 - 50 mmol, and even more preferably 2.5 - 25 mmol per 1 g of absolutely dry cellulose raw material. Also, for example, 1 - 40 mol is preferred per 1 mol of the N-oxyl compound.

[0035] The oxidation process of the cellulose raw material can proceed efficiently even under relatively mild conditions. Therefore, the reaction temperature is preferably 4 to 40 °C, and it may also be at room temperature of about 15 to 30 °C. As carboxyl groups are generated in the cellulose during the reaction, the pH of the reaction solution decreases. In order to efficiently proceed the oxidation reaction, it is preferable to add an alkaline solution such as an aqueous sodium hydroxide solution to the reaction system as needed to maintain the pH of the reaction solution at 9 to 12, preferably about 10 to 11. The reaction medium is preferably water in view of ease of handling and difficulty in occurring side reactions. The reaction time in the oxidation reaction can be appropriately set according to the degree of progress of oxidation, and is usually 0.5 to 6 hours, for example, about 0.5 to 4 hours. The concentration of the cellulose raw material during the oxidation reaction is not particularly limited, but is preferably 5% by mass or less.

[0036] Also, the oxidation reaction may be carried out in two steps. For example, by oxidizing the oxidized cellulose obtained by filtration after the completion of the first-step reaction again under the same or different reaction conditions, carboxyl groups can be efficiently introduced into the cellulose raw material without being inhibited by the salts by-produced in the first-step reaction.

[0037] As another example of the oxidation (carboxylation) method, a method of oxidizing by ozone treatment can be mentioned, and thereby ozone-oxidized cellulose fibers can be obtained. By defibrating the ozone-oxidized cellulose fibers by the method described later, ozone-oxidized cellulose microfibers can be obtained. Among the ozone-oxidized cellulose microfibers and TEMPO-oxidized cellulose microfibers, it is preferable to use TEMPO-oxidized cellulose microfibers.

[0038] The amount of carboxyl groups contained in the oxidized cellulose microfibrils obtained by defibrating oxidized cellulose fibers, relative to the absolute dry mass of the cellulose microfibrils, is preferably 0.6 mmol / g or more, more preferably 0.8 mmol / g or more, still more preferably 1.0 mmol / g or more. The upper limit is preferably 2.2 mmol / g or less, more preferably 2.0 mmol / g or less, still more preferably 1.8 mmol / g or less. Therefore, 0.6 mmol / g to 2.2 mmol / g is preferable, 0.8 mmol / g to 2.0 mmol / g is more preferable, and 1.0 mmol / g to 1.8 mmol / g is still more preferable.

[0039] The amount of carboxyl groups in the oxidized cellulose fibers can be measured by the following procedure: Prepare 60 mL of a 0.5% by mass slurry (aqueous dispersion) of oxidized cellulose fibers, add 0.1 M hydrochloric acid aqueous solution to adjust the pH to 2.5, and then dropwise add 0.05 N sodium hydroxide aqueous solution to measure the electrical conductivity until the pH reaches 11. From the amount of sodium hydroxide (a) consumed in the neutralization stage of the weak acid where the change in electrical conductivity is gentle, the amount of carboxyl groups is calculated using the following formula. Amount of carboxyl groups [mmol / g of oxidized cellulose fibers] = a [mL] × 0.05 / mass of oxidized cellulose fibers [g]

[0040] The amount of carboxyl groups in the oxidized cellulose fibers can be adjusted by controlling reaction conditions such as the addition amount of the above-mentioned oxidizing agent and reaction time. The amount of carboxyl groups in the oxidized cellulose fibers and the amount of carboxyl groups when the oxidized cellulose fibers are defibrated into oxidized cellulose microfibrils are usually the same.

[0041] In the oxidized cellulose fibers obtained in the above process, the carboxyl groups introduced into the cellulose raw material are usually in the form of alkali metal salts such as sodium salts (this is called the "salt form"). Before the defibrination step, the alkali metal salt of the oxidized cellulose fibers may be substituted with other cation salts such as phosphonium salts, imidazolinium salts, ammonium salts, and sulfonium salts. The substitution can be carried out by known methods.

[0042] As a method for producing an esterified cellulose fiber (for example, a phosphoric acid esterified cellulose fiber, a phosphorous acid esterified cellulose fiber, etc.) which is a raw material for an esterified cellulose microfiber which is an example of a chemically modified cellulose microfiber, there are a method of mixing a powder or an aqueous solution of a phosphoric acid compound with a cellulose raw material, a method of adding an aqueous solution of a phosphoric acid compound to a slurry of a cellulose raw material, and the like. Examples of the phosphoric acid compound include phosphoric acid, polyphosphoric acid, phosphorous acid, hypophosphorous acid, phosphonic acid, polyphosphonic acid, or esters thereof. These may be in the form of salts. Among these, a compound having a phosphate group is preferable because it is low-cost, easy to handle, and can introduce a phosphate group into the cellulose of pulp fibers to improve fibrillation efficiency. Examples of the compound having a phosphate group include phosphoric acid, sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, sodium phosphite, potassium phosphite, sodium hypophosphite, potassium hypophosphite, sodium pyrophosphate, sodium metaphosphate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, tripotassium phosphate, potassium pyrophosphate, potassium metaphosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, triammonium phosphate, ammonium pyrophosphate, ammonium metaphosphate, and the like. These can be used alone or in combination of two or more to introduce a phosphate group. Among these, phosphoric acid, sodium salts of phosphoric acid, potassium salts of phosphoric acid, and ammonium salts of phosphoric acid are preferable from the viewpoints of high efficiency of phosphate group introduction, easy fibrillation in the following fibrillation step, and easy industrial application. Particularly, sodium dihydrogen phosphate and disodium hydrogen phosphate are preferable. Further, since the reaction can proceed uniformly and the efficiency of phosphate group introduction is high, it is desirable to use the phosphoric acid compound as an aqueous solution. The pH of the aqueous solution of the phosphoric acid compound is preferably 7 or less because the efficiency of phosphate group introduction is high, but pH 3 to 7 is preferable from the viewpoint of suppressing hydrolysis of cellulose fibers.

[0043] As a specific example of the method for producing a phosphoric acid esterified cellulose fiber, the following method can be mentioned. A phosphoric acid compound is added to a suspension of a cellulose raw material having a solid content concentration of 0.1 to 10% by mass while stirring to introduce a phosphate group into the cellulose. When the cellulose raw material is 100 parts by mass, the addition amount of the phosphoric acid compound is preferably 0.2 to 500 parts by mass, more preferably 1 to 400 parts by mass, in terms of the amount of phosphorus element. If the ratio of the phosphoric acid compound is equal to or higher than the lower limit value, the yield of the cellulose microfiber can be further improved. However, if it exceeds the upper limit value, the effect of improving the yield reaches a plateau, which is not preferable in terms of cost.

[0044] In addition to the phosphate compound, powders or aqueous solutions of other compounds may be mixed. The other compounds are not particularly limited, but nitrogen-containing compounds exhibiting basicity are preferred. Here, "basicity" is defined as the aqueous solution showing a pink to red color in the presence of a phenolphthalein indicator, or the pH of the aqueous solution being greater than 7. The nitrogen-containing compound exhibiting basicity is not particularly limited as long as the effects of the present invention are not impaired, but a compound having an amino group is preferred. For example, urea, methylamine, ethylamine, trimethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, pyridine, ethylenediamine, hexamethylenediamine, etc. may be mentioned. Among them, urea, which is low-cost and easy to handle, is preferred. The addition amount of the other compound is preferably 2 to 1000 parts by mass, more preferably 100 to 700 parts by mass, based on 100 parts by mass of the solid content of the cellulose raw material. The reaction temperature is preferably 0 to 95°C, more preferably 30 to 90°C. The reaction time is not particularly limited, but is about 1 to 600 minutes, more preferably 30 to 480 minutes. When the conditions of the esterification reaction are within these ranges, it is possible to prevent the cellulose from being excessively esterified and becoming easily soluble, and the yield of the phosphoric acid esterified cellulose becomes good. After dehydrating the obtained phosphoric acid esterified cellulose suspension, from the viewpoint of suppressing the hydrolysis of cellulose, it is preferable to perform heat treatment at 100 to 170°C. Further, while water is contained during the heat treatment, it is preferable to heat at 130°C or lower, preferably 110°C or lower, and after removing the water, it is preferable to perform heat treatment at 100 to 170°C.

[0045] The degree of substitution of phosphate groups per glucose unit of the phosphorylated cellulose fiber is preferably 0.001 or more and less than 0.40. By introducing a phosphate group substituent into cellulose, the celluloses repel each other electrically. Therefore, the cellulose into which the phosphate group has been introduced can be easily defibrated. If the degree of substitution of phosphate groups per glucose unit is less than 0.001, it cannot be sufficiently defibrated. On the other hand, if the degree of substitution of phosphate groups per glucose unit is greater than 0.40, it may swell or dissolve, and thus may not be obtained as microfibrils. In order to efficiently perform defibration, it is preferable that the phosphorylated cellulose raw material obtained above is boiled and then subjected to a washing treatment such as washing with cold water. These modifications by esterification are modifications by substitution reactions. The degree of substitution in the phosphorylated cellulose fiber and the degree of substitution when it is made into phosphorylated cellulose microfibrils are usually the same.

[0046] In the phosphorylated cellulose fiber obtained in the above step, the phosphate group introduced into the cellulose raw material is usually in the form of an alkali metal salt such as a sodium salt (this is referred to as the "salt form"). Before the defibration step, the alkali metal salt of the phosphorylated cellulose fiber may be substituted with another cation salt such as a phosphonium salt, an imidazolinium salt, an ammonium salt, or a sulfonium salt. The substitution can be carried out by a known method.

[0047] (Defibration) The apparatus for defibrating cellulose raw materials or chemically modified cellulose raw materials (chemically modified cellulose fibers) is not particularly limited. For example, it is preferable to apply a shearing force to the raw materials (usually an aqueous dispersion of the raw materials) using a defibrating apparatus such as a high-speed rotation type, a colloid mill type, a high-pressure type, a roll mill type, an ultrasonic type, etc., or a refiner, a cavitation jet apparatus, etc. In particular, it is preferable to use a cavitation jet apparatus that can efficiently defibrate at a pressure of about 7 MPa, or a wet high-pressure or ultra-high pressure homogenizer that can apply a pressure of 50 MPa or more to the raw materials (usually an aqueous dispersion) and apply a strong shearing force. Also, prior to the defibrating and dispersing treatment, if necessary, a pretreatment can be performed. The pretreatment can be carried out using known mixing, stirring, emulsifying, and dispersing apparatuses such as a high-speed shearing mixer. The number of passes (treatment times) in the defibrating apparatus may be once or two or more times, and two or more times are preferable.

[0048] When performing defibrillation, usually, first, a cellulose raw material or a chemically modified cellulose fiber is dispersed in a dispersion medium to prepare a dispersion. The dispersion medium is not particularly limited as long as it can disperse the cellulose raw material and the chemically modified cellulose fiber. Examples include water, an organic solvent, and a mixed solvent thereof.

[0049] The solid content concentration of the cellulose raw material or the chemically modified cellulose fiber in the dispersion is usually 0.1% by mass or more, preferably 0.2% by mass or more, and more preferably 0.3% by mass or more. Thereby, the amount of the liquid with respect to the amount of the solid content becomes an appropriate amount and is efficient. The upper limit is usually 10% by mass or less, preferably 6% by mass or less. Thereby, fluidity can be maintained.

[0050] Prior to defibrillation, a pretreatment may be performed if necessary. The pretreatment may be carried out using a mixing, stirring, emulsifying, or dispersing apparatus such as a high-speed shearing mixer.

[0051] In the present invention, it is preferable to defibrate the cellulose microfibers until they become CNF. By advancing the defibration to the nanofiber level, they can be easily and uniformly mixed when added to the pancake batter, and the effects of the present invention can be more effectively exerted.

[0052] (Drying) The cellulose microfibers used in the present invention can be used in the state of the dispersion liquid obtained after defibration, but can also be dried as necessary and redispersed in water for use. The drying method is not limited in any way, and for example, known methods such as freeze-drying method, spray-drying method, shelf drying method, drum drying method, belt drying method, method of thinly spreading on a glass plate etc. and drying, fluidized bed drying method, microwave drying method, heat-generating fan type vacuum drying method can be used. After drying, if necessary, it can be pulverized with a cutter mill, hammer mill, pin mill, jet mill etc. Also, the method of redispersion in water is not particularly limited, and known dispersion devices can be used.

[0053] The form of the cellulose microfibers used in the present invention may be in the state of a dispersion liquid or in a powder form, but if it is in a powder form, it can be used as it is as the mixed powder of the pancake batter, so it is excellent in workability, and it is preferable to use it in a powder state.

[0054] In the present invention, the blending amount of the cellulose microfibers is preferably 0.01 to 5% by mass, more preferably 0.05 to 5% by mass, and still more preferably 0.1 to 3% by mass in terms of solid content based on the cereal grains.

[0055] The cellulose microfibers of the present invention may contain other components as necessary. For example, when producing a powder, it is preferable to coexist a water-soluble polymer in the dispersion of the cellulose microfibers before drying because the redispersibility is improved.

[0056] (Water-soluble polymer) Examples of the water-soluble polymer include cellulose derivatives (carboxymethyl cellulose, methyl cellulose, hydroxypropyl cellulose, ethyl cellulose), xanthan gum, xyloglucan, dextrin, dextran, carrageenan, locust bean gum, alginic acid, alginate, pullulan, starch, arrowroot powder, kudzu powder, corn starch, gum arabic, locust bean gum, gellan gum, polydextrose, pectin, chitin, water-soluble chitin, chitosan, casein, albumin, soy protein hydrolyzate, peptone, tamarind gum, guar gum, and the like. Among these, cellulose derivatives are preferable from the viewpoint of affinity with carboxymethylated cellulose fine fibers, and carboxymethyl cellulose and its salts are particularly preferable. Water-soluble polymers such as carboxymethyl cellulose and its salts are considered to improve redispersibility by entering between carboxymethylated cellulose fine fibers and increasing the distance between the fine fibers.

[0057] When carboxymethyl cellulose or its salt is used as the water-soluble polymer, it is preferable to use carboxymethyl cellulose having a degree of carboxymethyl group substitution of 0.55 to 1.6 per anhydroglucose unit, more preferably 0.55 to 1.1, and even more preferably 0.65 to 1.1. Also, those with longer molecules (higher viscosity) are preferable because they have a higher effect of increasing the distance between the fine fibers. Further, the B-type viscosity at 25°C and 60 rpm in a 1% by mass aqueous solution of carboxymethyl cellulose is preferably 3 mPa·s to 14000 mPa·s, more preferably 7 mPa·s to 14000 mPa·s, and even more preferably 1000 mPa·s to 8000 mPa·s. Here, the "carboxymethyl cellulose or its salt" as the water-soluble polymer is completely dissolved in water, and thus is distinguished from the carboxymethylated cellulose fibers whose fiber shape can be confirmed in water as described above.

[0058] The blending amount of the water-soluble polymer is preferably 5% by mass to 300% by mass, more preferably 20% by mass to 300% by mass, still more preferably 25% by mass to 200% by mass, and still more preferably 25% by mass to 60% by mass based on the cellulose microfibrils (dry solid content).

[0059] The pancake batter of the present invention can be prepared without problems by a known method. For example, a mixed powder containing rice flour and powdery cellulose microfibrils is prepared, and the mixed powder is appropriately dissolved in milk, soy milk, water, etc., and stirred well until it becomes whipped to obtain it.

[0060] When the cellulose microfibrils are made into a dispersion liquid in advance, it can be obtained in the same manner by adding them to milk, soy milk, water, etc. instead of the mixed powder.

Examples

[0061] Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

[0062] (Method for measuring degree of carboxymethyl substitution) 1) Weigh accurately about 2.0 g of carboxymethylated cellulose fiber (dry) and put it into a 300 mL volumetric Erlenmeyer flask with a stopper. 2) Add 100 mL of a solution prepared by adding 100 mL of special grade concentrated nitric acid to 1000 mL of nitric acid methanol, shake for 3 hours to convert carboxymethyl cellulose salt (CM cellulose) into hydrogen-type CM cellulose. 3) Weigh accurately 1.5 - 2.0 g of hydrogen-type CM cellulose (dry) and put it into a 300 mL volumetric Erlenmeyer flask with a stopper. 4) Moisten the hydrogen-type CM cellulose with 15 mL of 80% methanol, add 100 mL of 0.1 N NaOH, and shake at room temperature for 3 hours. 5) Using phenolphthalein as an indicator, back-titrate the excess Na OH with 0.1 N H2SO4. ​6) Calculate the degree of carboxymethyl substitution (DS) using the following formula: A = [(100 × F’ - (mL of 0.1N H2SO4) × F) × 0.1] / (dry mass (g) of hydrogenated C methylcellulose) DS = 0.162 × A / (1 - 0.058 × A) A: Amount (mL) of 1N NaOH required for neutralization of 1 g of hydrogenated CM cellulose F’: Factor of 0.1N H2SO4 F: Factor of 0.1N NaOH

[0063] (Method for measuring average fiber diameter and aspect ratio) The average fiber diameter and average fiber length of CNF were analyzed for 200 randomly selected fibers using an atomic force microscope (AFM). The aspect ratio was calculated using the following formula. Aspect ratio = average fiber length / average fiber diameter

[0064] [Example 1] (Preparation of carboxymethylated cellulose nanofibers) To a 5 L twin-screw kneader with the rotation speed adjusted to 100 rpm, 1089 parts of isopropanol (IPA) and a solution of 31 parts of sodium hydroxide dissolved in 121 parts of water were added, and 200 parts were charged based on the dry mass when hardwood pulp (manufactured by Nippon Paper Industries Co., Ltd., LBKP) was dried at 100 °C for 60 minutes. It was stirred and mixed at 30 °C for 60 minutes to prepare mercerized cellulose. While further stirring, 117 parts of sodium monochloroacetate were added, stirred at 30 °C for 30 minutes, then heated to 70 °C over 30 minutes, and a carboxymethylation reaction was carried out at 70 °C for 60 minutes. The proportion of water in the reaction medium during the mercerization reaction and the carboxymethylation reaction was 10% by mass. After completion of the reaction, it was neutralized, washed with 65% hydrous methanol, de-liquored, dried, and pulverized to obtain a sodium salt of carboxymethylated cellulose with a degree of carboxymethyl substitution of 0.27 and a crystallinity of cellulose I type of 64%. The measurement methods for the degree of carboxymethyl substitution and the crystallinity of cellulose I type are as described above.

[0065] The sodium salt of the obtained carboxymethylated cellulose was dispersed in water to form a 1% (w / v) aqueous dispersion. This was treated three times with a high-pressure homogenizer at 150 MPa to obtain a dispersion of carboxymethylated cellulose nanofibers. The obtained carboxymethylated cellulose nanofibers had an average fiber diameter of 3.2 nm and an aspect ratio of 40.

[0066] The obtained carboxymethylated cellulose nanofibers were made into a dispersion with a solid content of 0.7% by mass in water, and carboxymethyl cellulose (manufactured by Nippon Paper Industries Co., Ltd., trade name: F350HC-4, viscosity (1% by mass, 25 °C, 60 rpm) of about 3000 mPa·s, degree of carboxymethyl substitution of about 0.90) was added at 40% by mass based on the carboxymethylated cellulose nanofibers (that is, when the solid content of the carboxymethylated cellulose nanofibers was 100 parts by mass, the solid content of carboxymethyl cellulose was 40 parts by mass), and the mixture was stirred with a TK homomixer (12,000 rpm) for 60 minutes.

[0067] To this dispersion, an aqueous sodium hydroxide solution of 0.5% by mass was added to adjust the pH to 9, and then it 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 obtained dried product was scraped off, and then the dried product was pulverized at a speed of 10 kg per hour using an impact mill to obtain a dried pulverized product with a moisture content of 5% by mass. The obtained pulverized product was classified using a 30-mesh sieve to obtain a powder (CNF powder) containing carboxymethylated cellulose nanofibers and carboxymethyl cellulose.

[0068] (Adjustment of the mixed powder) 100 parts by weight of rice flour, 30 parts by weight of sugar, 0.5 part by weight of salt, 6 parts by weight of powdered oil and fat (manufactured by Miyoshi Oil & Fat Co., Ltd.), 4.5 parts by weight of baking powder (manufactured by Suzukisho Co., Ltd.), 0.2 part by weight of powdered vanilla flavor (manufactured by Shiono Flavor Co., Ltd.), and 1.4 parts by weight of the CNF powder obtained above were put into a stainless steel bowl and mixed evenly to obtain a mixed powder.

[0069] (Adjustment of pancakes) To 200 parts by weight of unadjusted soy milk (manufactured by Marusanai Co., Ltd.), 100 parts by weight of the mix powder obtained as described above and an emulsifier preparation (manufactured by Mitsubishi Chemical Corporation) were added, and stirring was continued until it became whipped to obtain a pancake batter composition.

[0070] Approximately 35 g of the obtained pancake batter composition was poured onto a frying pan heated to a surface temperature of 160 to 180 °C in a circular shape, baked on one side for 3.5 minutes, turned over, and baked for 4.5 minutes to obtain pancakes.

[0071] [Comparative Example 1] A mix powder was obtained and pancakes were prepared in the same manner as in Example 1, except that no CNF powder was added.

[0072] <Evaluation of Pancake Appearance / Inner Layer> The baked pancakes were placed on a horizontal table and visually observed from the top surface. Further, the central portion of the pancake was cut, and the cut surface was visually observed. Also, 5 baked pancakes were stacked on a horizontal table, and the height from the side was visually observed and evaluated according to the following criteria.

[0073] (Observation from the Top Surface) 〇: The batter has spread neatly in a circular shape, and there is no problem with the shape of the pancake. (Observation of the Cross-Section) 〇: The batter has swollen, and there is also little generation of bubbles, etc. ×: The swelling of the batter is insufficient, and it is not suitable as a pancake. (Observation of the Height) 〇: Each one has sufficient swelling and is a pancake with volume. ×: Overall, the swelling of the batter is insufficient, and a sense of insufficiency is felt when stacking and decorating.

[0074]

Table 1

[0075] The pancake of the present invention can obtain a pancake made of rice flour that has a good appearance due to the inclusion of cellulose microfibers, generates few bubbles, etc., and has a sense of volume even without the inclusion of egg yolks or egg whites.

Claims

1. A pancake batter characterized by containing rice flour and cellulose microfibers.

2. The pancake batter according to Claim 1, characterized by not containing egg yolk.

3. The pancake batter according to any one of Claims 1 to 2, characterized by not containing gluten.

4. The pancake batter according to any one of Claims 1 to 2, characterized in that the cellulose microfibers are carboxymethylated.

5. The pancake batter according to any one of Claims 1 to 2, characterized in that the cellulose microfibers are cellulose nanofibers.

6. A method for manufacturing a pancake, which can be obtained by baking the pancake batter according to any one of Claims 1 to 5.

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