JP7235498B2 - Method for producing konjac powder - Google Patents

Description

The present invention relates to a method for producing konjac powder by converting water-soluble dietary fiber in powder particles contained in konjac powder into insoluble dietary fiber and changing the ratio of these.

Konnyaku is made by dissolving refined konjac powder, which is obtained by pulverizing dried konjac potatoes, in water to make konjac paste. In general, a suspension of slaked lime (calcium hydroxide powder) dispersed in water is added to the konjac paste. It is produced by a method of mixing and kneading well, molding, and heating and solidifying.
Konjac has long been eaten in Japan, China, and some parts of Southeast Asia, but with the recent health food boom, konnyaku has come into the limelight as a food containing insoluble dietary fiber.
The main component of konjac potato is water-soluble glucomannan, which becomes a pasty sol when dissolved in water, but becomes insoluble and gels when heated under alkaline conditions, and becomes konjac by absorbing water. Alkaline coagulants used in konjac production are mainly calcium hydroxide, sodium hydroxide or sodium carbonate. In this reaction, the acetyl groups in water-soluble glucomannan (water-soluble dietary fiber) are said to be released under alkaline conditions, resulting in gelation (conversion to insoluble dietary fiber).

As a processed konjac product with an increased content of insoluble dietary fiber, konjac powder obtained by drying konjac and then milling is known. Patent Document 1 discloses a method for producing konjac powder, in which konjac containing water is crushed into minced meat, then washed with water to remove harshness, dehydrated, and the resulting konjac paste is dried and powdered with a mill. ing.
Patent Document 2 discloses a modified konjac powder obtained by heat-treating konjac powder with an alkaline solution while suppressing the swelling of konjac grains, dispersing it in water to form a dispersion, followed by heat treatment. Alternatively, modified konjac flour is disclosed that is prepared to gel when agitated.

JP-A-4-99453 JP 2011-72304 A

The insoluble dietary fiber powder of konjac according to the prior art represented by Patent Document 1 has a high insoluble dietary fiber content and is much easier to handle than konjac containing a large amount of water. It is an excellent product for However, the powder particles contained in the konjac powder according to the prior art have low water absorbency or no water absorbency, and the texture when ingested as it is is unique, and there are cases where the application is limited.
In Patent Document 1, konjac powder, which is a raw material, is dissolved in water (generally at a concentration of 3% by mass) to prepare a so-called konjac paste, and then alkali is added and heated to obtain konjac. The resulting konjac fiber fraction is wet-pulverized, washed with water to remove harshness and dehydrated, and the resulting konjac fiber fraction is dried and then pulverized into a powder. This makes it possible to obtain konjac powder with a high content of insoluble dietary fiber. However, in the method of Patent Document 1, the number of manufacturing steps increases and the manufacturing steps become complicated, making it difficult to improve the efficiency of manufacturing.
Therefore, in the production of konjac powder according to the prior art, many processes such as preparation of konjac paste containing a large amount of water, alkali addition, molding, heating, cooling, shredding, dehydration, drying and pulverization are essential. In addition, the yield (mass basis) of konjac powder to konjac paste was low, and there was a limit to increasing the production efficiency of konjac powder.
Patent Document 2 discloses a method for producing modified konjac flour by adding an alkaline solution to konjac flour, which is a raw material, or by adding an alkaline solution and a swelling inhibitor such as ethanol and performing heat treatment. In this production method, the konjac flour, which is a raw material, is treated with an alkaline solution while maintaining its powdery state. If this modified konjac powder is dispersed in water and heat-treated, it will gel as it is.
The modified konjac flour disclosed in Patent Document 2 has gelling ability and is used as a gelling agent. Therefore, this modified konjac flour does not have physical properties suitable for applications in which konjac flour containing insoluble dietary fiber is used in a powder state without forming a gel.

The object of the present invention is to dramatically increase the content of insoluble dietary fiber relative to the konjac raw material powder, which is useful for direct ingestion of water-soluble dietary fiber and insoluble dietary fiber in the powder state and blending into foods. Another object of the present invention is to provide a method for producing konjac powder.

The method for producing konjac powder according to the present invention includes:
A mixing step of mixing the konjac raw material powder and an alkali metal solution and supplying the alkali metal solution to the powder particles contained in the konjac raw material powder;
an insoluble dietary fiber forming step for obtaining konjac powder by forming insoluble dietary fiber in the powder particles supplied with the alkali metal solution by the action of the alkali metal solution,
The mixing step and the insoluble dietary fiber forming step are characterized in that the powder particles are maintained in the form of particles.

According to the present invention, an alkali metal solution is added to the konjac flour as a raw material, and the powder particles of the konjac flour are mixed while maintaining the shape of the particles, and supplied to the surface and inside of the powder particles. It is possible to obtain konjac powder containing powder particles having no gelling ability and having an increased content of insoluble dietary fiber generated by the action of the alkali metal solution.
The ratio of insoluble dietary fiber to water-soluble dietary fiber contained in the konjac powder can be controlled by selecting reaction conditions between the alkali metal solution and the konjac raw material powder.
According to the method of the present invention, the formation of insoluble dietary fiber from glucomannan causes the konjac raw material powder to lose its gelling ability. That is, the conversion of glucomannan, which is contained as water-soluble dietary fiber, into insoluble dietary fiber is carried out so as to eliminate the gelling ability of the konjac raw material powder. Whether or not the konjac powder has lost its gelling ability, that is, whether or not it has become non-gel-forming, can be confirmed by the method of measuring the viscosity of the konjac powder dispersion, which will be described later.
It is preferable that the content of insoluble dietary fiber relative to the total dietary fiber per dry matter of the non-gelling konjac powder is 50% by mass or more. Although the upper limit of the insoluble dietary fiber content per dry matter is not particularly limited, the insoluble dietary fiber content relative to the total dietary fiber per dry matter can be less than 100% by mass, or 99% by mass or less.
Furthermore, in the method for producing konjac powder according to the present invention, the desired konjac powder can be obtained directly by allowing the alkali metal solution to act while maintaining the particle morphology of the powder particles contained in the konjac raw material powder. Therefore, in the method for producing konjac powder according to the present invention, the steps in the conventional technology include the steps of preparing konjac paste, adding an alkaline coagulant and heating the konjac paste to gel it, shredding the konjac mass containing water, and dehydrating it. By omitting the steps of drying and pulverizing, it is possible to produce konjac powder containing 50% by mass or more of insoluble dietary fiber with respect to total dietary fiber very efficiently.
The konjac powder according to the present invention contains water-soluble dietary fiber and insoluble dietary fiber, is insoluble in water, has excellent dispersibility in water and water holding property (swelling property), and can be used as it is in the form of powder. Alternatively, it can be used as a mixture of water-soluble dietary fiber and insoluble dietary fiber in beverages and foods by adding them to beverages and foods.

In order to solve the technical problems associated with conventional konjac insoluble dietary fiber powders represented by the above-mentioned Patent Document 1, the present inventors have extensively studied methods for producing konjac powder. As a result, the glucomannan (water-soluble dietary fiber) in the konjac raw material powder is not dissolved in water, but maintained in a state of being confined in the powder particles to form an insoluble dietary fiber from the water-soluble dietary fiber. is possible, and if the ratio can be freely controlled, it is possible to provide a konjac powder that can be used in a wide range of applications and has good production efficiency.
That is, according to the 2015 edition of the Standard Tables of Food Composition in Japan (Ministry of Education, Culture, Sports, Science and Technology, Chemical Technology and Academic Council, Edited by the Resource Survey Subcommittee), the dietary fiber content in refined konjac is 0.1% water-soluble dietary fiber. , Insoluble dietary fiber is 2.1%, but according to the standard food composition table, the raw material, konjac flour, has 73.3% water-soluble dietary fiber and 6.6% insoluble dietary fiber. there is Therefore, in order to use the insoluble dietary fiber of konjac more actively and more widely than ever before, instead of extracting insoluble dietary fiber from konjac with an insoluble dietary fiber content of 2.1%, It is important to directly convert the water-soluble dietary fiber in refined konjac flour, which is the raw material, into insoluble dietary fiber.

On the other hand, Patent Document 2 describes that konjac powder is modified by heat treatment with an alkaline solution, and when this is dispersed in water and heat treated, it gels as it is. The purpose of Patent Document 2 is to disperse the konjac powder in water, make it pasty, and then mix the alkali and heat it to gel it without going through the normal procedure, from the modified konjac powder. The point is that a heated gel can be easily obtained. However, in the method disclosed in Patent Document 2, there is a possibility that part of the glucomannan, which is a water-soluble dietary fiber in the modified konjac flour, is converted to insoluble dietary fiber, but the gelling ability as a whole It is a major premise that
According to the studies of the present inventors, in the konjac powder treated with an alkaline agent, the content of insoluble dietary fiber in the konjac powder measured by the modified Prosky method is 40% by mass or more with respect to the total dietary fiber content. It was found that the gelling ability was lost when the temperature increased.
That is, according to the 2015 edition of the Standard Tables of Food Composition in Japan, refined konjac flour contains 6.6% insoluble dietary fiber and 73.3% water-soluble dietary fiber, so at least By directly converting 35% or more to insoluble dietary fiber, the ratio of insoluble dietary fiber to the total dietary fiber in the refined konjac flour can be 40% by mass or more, and konjac flour that does not gel. It becomes. Therefore, it can be said that Patent Document 2 does not assume that 35% by mass or more of the water-soluble glucomannan in the raw material konjac flour is made into insoluble dietary fiber.
Further, Patent Documents 1 and 2 do not describe or suggest controlling the ratio of water-soluble dietary fiber and insoluble dietary fiber contained in each particle of konjac powder.

The present inventors have already developed a new manufacturing technology that converts water-soluble konjac powder into insoluble konjac powder in powder form without dissolving water-soluble konjac powder in water and making it pasty by using an aqueous sugar calcium hydroxide solution. In this production technique, the sugar calcium hydroxide aqueous solution is directly absorbed into the powder particles contained in the konjac raw material powder, and glucomannan, which is a water-soluble dietary fiber, is insolubilized in the powder particles.
The sugar calcium hydroxide aqueous solution reacts gently with the water-soluble konjac flour, and at the same time, the concentration of calcium hydroxide to be added can be easily controlled from a low concentration to a high concentration that cannot be achieved with calcium hydroxide alone. It has the great merit of ensuring a quantitative and highly reproducible response in conversion to dietary fiber.

The present inventors have found that the alkaline agent for increasing the content of insoluble dietary fiber in the konjac raw material powder is not a calcium compound such as calcium hydroxide, but an alkali metal compound such as a sodium compound and a potassium compound. , an alkaline agent with a simpler composition was investigated. As a result, sodium compounds and potassium compounds have extremely high reactivity with water-soluble dietary fiber, and new knowledge was obtained that they can be used even when the purity of the raw material, konjac powder, is low. rice field. In this way, the method using an alkali metal compound such as a sodium compound or a potassium compound also converts the water-soluble konjac powder into insoluble konjac powder in the form of powder particles without dissolving the water-soluble konjac powder in water to form a paste. It was found to be an effective method for
In particular, as a raw material, 0.1M to 1.0M of konjac powder containing 73.3% of water-soluble dietary fiber and 6.6% of insoluble dietary fiber, which is described in the above-mentioned Japanese Food Standard Ingredients Table, It was confirmed that a konjac powder having a ratio of insoluble dietary fiber to total dietary fiber of 50% by mass or more can be obtained by applying a sodium hydroxide solution or a potassium hydroxide solution.
The present invention has been made based on the above-described new findings by the inventors of the present invention.
One form of the method for producing konjac powder according to the present invention is
(A) a mixing step of mixing the konjac raw material powder and the alkali metal solution and supplying the alkali metal solution to the powder particles contained in the konjac raw material powder;
(B) an insoluble dietary fiber forming step of forming insoluble dietary fiber in the powder particles supplied with the alkali metal solution by the action of the alkali metal solution to obtain konjac powder having no gelling ability;
have The preferred insoluble dietary fiber content targeted here is 50% by mass or more relative to the total dietary fiber content in the konjac flour.
Therefore, in the above steps (A) and (B), the powder particles contained in the konjac powder are maintained in the form of particles, and the total dietary fiber contained in the konjac powder (water-soluble dietary fiber and insoluble dietary fiber) The ratio of insoluble dietary fiber (mass basis) to the total of konnyaku) is increased so that the gelling ability of the konjac raw material disappears. The ratio of insoluble dietary fiber to total dietary fiber can be less than 100% by mass, or 99% by mass or less.

In the present invention, the konjac raw material powder is konjac powder containing water-soluble glucomannan that can be used for the production of konjac or for the production of konjac, and dissolves in water. On the other hand, the konjac flour according to the present invention treated with an alkaline agent is konjac flour obtained by treating the konjac raw material powder by the above process, and the content of insoluble dietary fiber is absolutely Due to the large amount, it does not dissolve in water and does not have gelling ability, and is clearly distinguished from the konjac raw material powder. Therefore, the konjac raw material powder can be used for the production of konjac, but the konjac flour according to the present invention cannot be used to produce konjac or gel-like food as in Patent Document 2. Moreover, the konjac powder according to the present invention is clearly distinguished from conventional konjac powder as described in Patent Document 1 in that it contains water-soluble dietary fiber.

In the method for producing konjac powder of the present invention, first, a mixture of konjac raw material powder and an alkali metal solution is prepared. For the preparation of this mixture, a method of adding an alkali metal solution to the konjac raw material powder and mixing by stirring can be preferably used. A known stirring mixer can be used for mixing the konjac raw material powder and the alkali metal solution.
Furthermore, when adding and mixing the alkali metal solution to the konjac raw material powder, in order to maintain the shape of the powder particles as particles, the particles are partially formed by absorbing the alkali metal solution and binding the particles together. It is preferable to use a method in which the hard aggregates are loosened by stirring or the like to separate the particles. Furthermore, when the alkali metal solution is added and mixed in an amount more than twice the raw material konjac flour, it cannot be loosened even by strong stirring, etc., and a sponge-like state in which aggregates are formed occurs. The particles may be separated by stirring or the like. In addition, it is also possible to separate the particles by strong agitation after washing with hydrous alcohol, further neutralizing with acid, dehydration, drying, etc., while the aggregates are formed, or after the drying process. . That is, it is preferable to add and mix the alkali metal solution so that the alkali metal solution is uniformly absorbed by each grain of the konjac raw material powder.
The point of the present invention is how to infiltrate the alkali metal compound into the konjac raw material powder, and the alkali metal solution added to the raw material powder is completely absorbed and separates the individual powder particles. This is very important.

The konjac raw material powder can be used without any particular limitation as long as the desired konjac powder can be obtained by treatment with an alkali metal solution. As the konjac raw material powder, for example, commonly used special grade flour, first grade flour, or refined konjac flour such as Timac Mannan (manufactured by Orihiro Co., Ltd.) can be used.

The alkali metal compound contained in the alkali metal solution to be added to the konjac raw material powder is preferably a sodium compound or a potassium compound, and at least one of these can be used. Examples of sodium compounds include sodium hydroxide; inorganic salts of sodium such as sodium carbonate, sodium hydrogen carbonate, monosodium phosphate, disodium phosphate, trisodium phosphate, sodium pyrophosphate, sodium metaphosphate, and sodium polyphosphate; organic salts of sodium such as monosodium citrate, disodium citrate, and trisodium citrate; Potassium compounds include potassium hydroxide; potassium pyrophosphates such as potassium carbonate, potassium hydrogen carbonate, dipotassium hydrogen phosphate, dipotassium phosphate, tripotassium phosphate, potassium metaphosphate, potassium polyphosphate, and tetrapotassium pyrophosphate. inorganic salts of potassium; organic salts of potassium such as tripotassium citrate; and the like.
Among these, sodium hydroxide, potassium hydroxide and sodium carbonate are preferred, and it is preferred to use these compounds alone or in combination of two or more.
When two or more alkali metal compounds are used in combination, a solution containing two or more of these compounds can be prepared and used in the step of mixing with the konjac raw material powder. Also, two or more of these solutions can be prepared and used in the step of mixing with the konjac raw material powder.
The alkali metal solution comprises an alkali metal compound and a liquid medium for its dissolution. As the liquid medium, water that can be used for food production can be used. As the alkali metal solution, an aqueous solution of an alkali metal compound is preferred. Further, the alkali metal solution does not contain components such as sugars and alcohols, but is composed of water and an alkali metal compound, and has the alkali metal compound as a single component as an alkali component, that is, an aqueous solution in which the alkali component is an alkali metal compound. preferable.
The concentration of the alkali metal compound in the alkali metal solution is not particularly limited, and is set so as to obtain the desired conversion rate of water-soluble dietary fiber contained in the konjac raw material powder to insoluble dietary fiber. The concentration of the alkali metal compound in the alkali metal solution can be selected from the range of 0.1M to 5.0M, preferably from the range of 0.2M to 3.0M, more preferably from 0.4M to 2.0M. More preferably, it is selected from the range of 0.0M, and even more preferably from the range of 0.4M to 1.0M.
Furthermore, the pH of the alkali metal solution is not particularly limited as long as it is set so that the desired conversion rate of water-soluble dietary fiber contained in the konjac raw material powder to insoluble dietary fiber is obtained, but for example, 11.0 to 14 It is preferred to select from the range of .0.

The amount of the alkali metal solution added to the konjac raw material powder is such that the powder particles contained in the konjac raw material powder can maintain the form of particles, and the glucomannan contained in the konjac raw material powder is added to the insoluble dietary fiber. can be selected from the range in which the conversion rate of .
It is preferable to select the amount of the alkali metal solution added to the konjac raw material powder based on the concentration of the alkali metal compound contained in the alkali metal solution and the amount of water supplied from the alkali metal solution to the konjac raw material powder.
As a result of investigation by the present inventors, the addition of the alkali metal solution is preferably 0.5 to 10 times, more preferably 0.5 to 5 times, still more preferably 0.5 to 10 times the amount of the konjac raw material powder. It has been clarified that by increasing the amount by 5 to 1.5 times (based on mass), it is possible to allow the powder particles to absorb the alkali metal solution while maintaining the shape of the powder particles.

The mixture obtained in the mixing step is optionally stirred or allowed to stand for a period of time necessary for the formation of insoluble dietary fiber, performing an insoluble dietary fiber forming step to promote the production of insoluble dietary fiber, It is preferable to obtain a konjac powder with an increased proportion of insoluble dietary fiber.
In the insoluble dietary fiber forming step, an alkali metal solution is supplied to the powder particles contained in the konjac raw material powder, and insoluble dietary fiber is produced from the water-soluble glucomannan within the powder particles, that is, at least part of the surface and inside of the powder particles. It is formed.

The mixing step and the insoluble dietary fiber forming step can be partially overlapped or performed simultaneously.
When adding and absorbing the alkali metal compound to the raw material powder in the mixing step, moderate heating is preferable for promoting the conversion of glucomannan into insoluble dietary fiber. The temperature for heating is not particularly limited, but it is preferably selected from the range of 5°C to 80°C, preferably from the range of 30°C to 60°C. Thereafter, conversion to insoluble dietary fiber may be promoted by performing an insoluble dietary fiber forming step by heating at room temperature or moderately at about 5° C. to 80° C. and maintaining it for several hours to several days. .

The maintenance of the form of the powder particles as particles means that the powder particles contained in the konjac raw material powder are subjected to the treatment process with an alkali metal solution, including the mixing process and the insoluble dietary fiber forming process (conversion process) described above. It means that the state of the primary particles is maintained regardless of the presence or absence of changes in the outer shape and size of the particles, and swelling of the powder particles due to the penetration of the alkali metal solution into the powder particles, moisture, etc. Shrinkage of powder particles or change in particle shape or size due to ejection to the outside of the powder particles may also be included.
In the production method according to the present invention, in the step of mixing the konjac raw material powder and the alkali metal solution and the step of forming insoluble dietary fiber in the powder particles, the konjac raw material powder is processed in a powder state into konjac powder. in which the shape of the powder particles is maintained as particles.

It is presumed that when glucomannan comes into contact with an alkali metal solution, the action of the alkali metal compound forms a water-insoluble structure in which sugar chain macromolecules are linked via numerous cross-linking points, that is, an insoluble dietary fiber. It is considered that the formation of this water-insoluble structure progresses from the surface layer toward the center of the powder particles as the alkali metal solution permeates from the surface to the inside of the powder particles. Therefore, the ratio of water-soluble dietary fiber and insoluble dietary fiber in the dietary fiber contained in the konjac powder particles can be changed by changing the conditions under which the alkali metal solution is applied to the konjac raw material powder.
In addition, the network structure on the surface layer of the powder particles, which is presumed to be formed first, has water permeability, and even when the network structure is formed on the surface layer, the penetration of the alkali metal solution into the powder particles is prevented. It is considered that there will be no Furthermore, the formation of a water-insoluble network structure on the surface layer of the powder particles allows each powder particle to independently maintain its particle shape throughout the treatment process using the alkali metal solution. Even if the adhesion or adhesion between particles occurs temporarily, the particles are dispersed by appropriately loosening the particles to separate them, thereby suppressing subsequent adhesion or adhesion between the particles. A fine powder can be obtained.
In addition, the powder particles have water absorbency and water retentivity to retain absorbed water by forming a network structure composed of crosslinked gel of glucomannan on the surface and inside of the powder particles. This makes it possible to impart a good texture to the powder particles, and when added to beverages and foods, it is easy to mix with beverages and foods without impairing their texture and flavor.

The step of forming an insoluble dietary fiber is completed when the desired conversion of glucomannan into an insoluble dietary fiber is achieved. Regarding whether the desired konjac powder was obtained, the results of measuring the content of water-soluble and insoluble dietary fiber and their content ratio, the measured value of viscosity, observation of the state of dispersion in water or warm water, etc. can be confirmed by
When setting the end time of the insoluble dietary fiber formation process using the content ratio of water-soluble dietary fiber and insoluble dietary fiber, the content of water-soluble dietary fiber and insoluble dietary fiber in konjac flour obtained under various treatment conditions It is possible to use a method of measuring the amount ratio, preliminarily selecting treatment conditions that allow the target content ratio to be obtained, and treating the konjac raw material powder under the selected treatment conditions.
By sampling a test sample from the konjac powder during the treatment process with the alkali metal solution, measuring the viscosity of the aqueous dispersion, and observing the dispersion state in the aqueous dispersion, Insoluble dietary fiber It is also possible to confirm the end time of the forming process. When the ratio of insoluble dietary fiber to total dietary fiber increases and the gelling ability is lost, the konjac flour does not dissolve in the aqueous dispersion and retains its particle state, and the viscosity of the aqueous dispersion remains constant. not increase. For example, as shown in Experimental Examples and Examples to be described later, an aqueous dispersion of konjac powder having no gelling ability and having a predetermined concentration maintains a low viscosity of 200 mPa·s or less. Thus, the fact that the low viscosity state is maintained can be used as an indicator of the disappearance of the gelling ability. Furthermore, the ratio of insoluble dietary fiber to total dietary fiber used as an index of disappearance of gelling ability is preferably 50% by mass or more.

The mixture of the konjac raw material powder and the alkali metal solution remains as a wet powder during and at the end of the treatment with the alkali metal solution. The wet powder thus obtained or the dry powder obtained by drying the wet powder may optionally be subjected to a washing step and a drying step. The washing step may be used as a final step to stop the action of the alkali metal solution. In addition, during at least one step of the washing step, the drying step, and the neutralization step described later, or after at least one of these steps, the dispersibility of the powder particles is improved or the particle size of the powder particles is reduced. A pulverization treatment (including a fine pulverization treatment) for lowering may be added. The pulverization treatment is not particularly limited as long as the intended pulverization effect can be obtained, and a known pulverization treatment method can be used for the pulverization treatment. For example, for the pulverization treatment, at least one of dry pulverization treatment, wet pulverization treatment and wet pressure treatment, or a combination of a plurality of methods can be used. It is to adjust the particle size to make it a konjac powder having.

In the konjac powder obtained by converting part of the water-soluble dietary fiber into insoluble dietary fiber while maintaining the form of the powder particles of the raw material powder, the outer shell of each powder particle contains mainly insoluble food. It contains fiber, and is thought to contain mainly water-soluble dietary fiber.
When the powder particles are pulverized to reduce the particle size, crushing similar to cleavage occurs in the powder particles, resulting in particle sizes such as hemispherical, flaky, and partially broken spherical shapes. Particles are produced as fractures with reduced . That is, the outer shell portion of the powder particles containing insoluble dietary fiber is partially shaved or split to reduce the particle size of the powder particles. The pulverized product obtained by such a pulverization treatment, that is, the pulverized konjac flour obtained by converting part of the water-soluble dietary fiber in the konjac raw material powder to insoluble dietary fiber with an alkaline agent while maintaining the shape of the powder with an alkaline agent, It is believed that the portion containing water-soluble dietary fiber inside the powder particles before pulverization is easily exposed, and it is possible to make konjac powder in which both water-soluble dietary fiber and insoluble dietary fiber can be used more effectively. . Powder particles that have undergone such a pulverization process are a more preferable form for utilizing the properties and functions of both the water-soluble fibers and the insoluble fibers.
In the konjac powder after such pulverization, by effectively using the functions of both water-soluble dietary fiber and insoluble dietary fiber, water-holding capacity (swelling property) due to water absorption and multiple powder particles are weak in water. It acquires the association property of associating with binding force. These properties are not seen in the powder particles before pulverization, or are stronger than the powder particles before pulverization. , the powder particles before and after grinding can be distinguished.
The particle size of the powder particles before pulverization is based on the particle size of the powder particles contained in the konjac raw material powder, and varies depending on the type of konjac raw material powder. d50) lies between 300 μm and 400 μm. In order to obtain the above water-holding capacity (swelling property) and associativity, the pulverization conditions are set so that the median value before pulverization is reduced by pulverization.
The median value of the particle size distribution of the pulverized powder is preferably 120 μm or less, more preferably 100 μm or less, and still more preferably 30 μm or more and less than 100 μm. The konjac powder after pulverization preferably contains powder particles with a particle size in the range of 1 μm to 300 μm, but konjac powder with a particle size of 300 μm or more may be mixed.
The D50 value is calculated from the particle size distribution of the powder, and the particle size distribution of the powder can be determined by a known method. The above D50 value was calculated from the particle size distribution obtained by the laser diffraction/scattering method. The particle size distribution was measured by a laser diffraction/scattering method using a particle size distribution analyzer using Microtrac Bell's MT3300 series (LOW-WET).

According to the study of the present inventors, even by stirring in an acid aqueous solution (35 ° C.) of the disintegration test first liquid (pH 1.2) simulating the acidic conditions in the stomach, the powder particles after the above-mentioned pulverization treatment It was found that by swelling and associating, water is retained (water retention) to form a volume-expanded mass. It was also found that the agglomerates moderately crumbled into small agglomerates in the acid aqueous solution by vigorous shaking, and further the individual powder particles were dispersed. Furthermore, the state of association of powder particles in an acid aqueous solution with a median particle size distribution of 100 μm or less is similar to the state of raw cabbage, which is a typical dietary fiber, crushed by chewing with teeth. Compared to the ground paste (adjusted to pH 1.6), the powder particles with a particle size corresponding to the cell size of the cabbage grinds were found in a morphology similar to the structure of the cell aggregates found in the cabbage shreds. It turned out that they were meeting.
From the above new findings of the present inventor, the ratio of water-soluble dietary fiber and insoluble dietary fiber in the powder particles after pulverization is, for example, a range close to cabbage (water-soluble dietary fiber 0.4% to insoluble food Fiber 1.4%; see the Standard Tables of Food Composition in Japan 2015), and compared to other vegetables, the range is close to each level, so it is the same physiological as vegetables containing dietary fiber such as raw cabbage. It has become clear that it is possible to have a function, namely a water holding capacity, which is the inherent physicochemical property of dietary fiber. Therefore, it is clear that the powder particles according to the present invention can provide constipation relieving and constipation prevention effects, which are the physiological functions inherent in vegetable dietary fiber (Journal of Japan Food Industry Association, Vol. 37, No. 11, 916-933 (1990)).In addition, the water absorption of the powder after pulverization is improved, and the time until swelling due to absorption of water in the digestive system including the stomach is shortened, making it more effective. It can be expected that the physiological function will be exhibited in a short period of time.

Furthermore, in the konjac powder after pulverization, as in the konjac powder before pulverization, the ratio of total dietary fiber in the powder particles can be adjusted to at least 80% by mass or more, and further 90% by mass or more. In addition, the following effects can be obtained by adjusting the ratio of water-soluble dietary fiber and insoluble dietary fiber, including the ratio in fibrous vegetables including cabbage.
(1) The content of water and dietary fiber in raw cabbage is 92.7% water, 0.4% water-soluble dietary fiber, and 1.4% insoluble dietary fiber according to the 2015 edition of the Standard Tables of Food Composition in Japan. . For example, it is necessary to obtain a mass of powder swollen by enclosing water of the same volume as the volume of pulverized material of 60 g of raw cabbage (1.1 g of dietary fiber) that imitates the state of being chewed with teeth. The amount of konjac powder after pulverization can be reduced to about 2 g, and even with such a small amount, it is possible to take in about 1.8 g of dietary fiber.
(2) When the intake of dietary fiber per day is set at around 3 to 8 g, raw cabbage has a large water content, and a relatively large amount of 160 g to 400 g is required to achieve this intake. However, the dietary fiber content of konjac powder after pulverization is much higher than that of raw cabbage, and it is possible to easily achieve such intake.
(3) The ratio of soluble dietary fiber to the total dietary fiber amount of raw cabbage is 22%, and the ratio of insoluble dietary fiber is 78%. , there is also variation in the total content ratio of these, and it may be difficult to always obtain vegetables of stable quality. On the other hand, konjac powder after pulverization can be made into a product with a stable ratio of water-soluble and insoluble dietary fibers and a total content ratio of these, which guarantees quantitative intake of dietary fiber. be able to. For example, if it is carried as a capsule type, it will have the great merit that it can always be taken before meals.
(4) Raw vegetables cannot be stored for a long time at room temperature, and it is necessary to always obtain fresh raw vegetables. On the other hand, the konjac powder after pulverization is a dried product and has high storage stability, enabling long-term storage and stable supply.
From the above points, the konjac powder after pulverization has preferable properties for continuing the intake of dietary fiber in a quantitative manner on a daily basis.
In order to obtain the effects described above, the ratio of dietary fiber in the ground konjac powder is preferably in the range of 50% by mass to 98% by mass. Furthermore, in order to make the ratio of water-soluble dietary fiber and insoluble dietary fiber equivalent to that of fibrous vegetables, it is preferable that the water-soluble dietary fiber is in the range of 1% by mass to 60% by mass with respect to the total dietary fiber. More preferably, the range is from 40% to 99% by mass, more preferably from 50% to 98% by mass.

Konjac powder after pulverization has high water absorbency, swells and disperses in water, and does not easily precipitate. It can be suitably used in food production for reinforcing dietary fiber. Furthermore, it can be suitably used as a dietary fiber component of food compositions such as functional foods such as supplements and foods for specified health uses.
The swellability of the konjac powder after pulverization can be controlled by the target particle size and particle size distribution in the pulverization, the type of alkaline agent, treatment conditions with the alkaline agent, and the like. From these points, it is more preferable to use a potassium compound, preferably potassium hydroxide, as the alkaline agent. Moreover, by using a potassium compound as an alkaline agent, konjac powder can be used for potassium intake in addition to dietary fiber.

The cleaning agent for cleaning the konjac powder is not particularly limited as long as it is a cleaning agent capable of washing and removing from the konjac powder excess alkali metal compounds that have not been used for conversion of glucomannan into insoluble dietary fiber, i.e. dealkalization. Available. As the cleaning agent, for example, alcohol-containing water containing 10 to 50% by mass of volatile alcohol such as ethanol is preferable.

During or after the washing step, an optional neutralization step with acid may be added. Acids used for neutralization are preferably those used as acid components of acidifying agents used in foods. Examples of such acids include organic acids such as citric acid and malic acid, and inorganic acids such as hydrochloric acid, phosphoric acid and phosphates. The acid can be added to the cleaning solution in powder or particulate form, or can be used as an aqueous solution in the neutralization process, the concentration of the acid being selected to achieve the desired neutralizing effect. For example, an aqueous solution with an acid concentration of 1 to 10% by mass can be preferably used.

The drying process can be performed under conditions according to the moisture content of the desired konjac powder, and can be performed using a known powder drying apparatus. The moisture content of the konjac powder after the drying step can be, for example, 10% by mass or less, preferably in the range of 2 to 8% by mass.
One form of a manufacturing method having a washing step and a drying step can have the following steps.
(A) A mixing step of mixing the konjac raw material powder and the alkali metal solution and supplying the alkali metal solution to the powder particles contained in the konjac raw material powder.
(B) A step of forming insoluble dietary fiber in the powder particles to which the alkali metal solution has been supplied to form insoluble dietary fiber by the action of the alkali metal solution to obtain konjac powder.
(C) A washing step of washing the konjac powder.
(D) A drying step of drying the konjac powder that has undergone the washing step.
Moreover, one form of the manufacturing method having a washing step, a neutralization step and a drying step can have the following steps.
(A) A mixing step of mixing the konjac raw material powder and the alkali metal solution and supplying the alkali metal solution to the powder particles contained in the konjac raw material powder.
(B) A step of forming insoluble dietary fiber in the powder particles to which the alkali metal solution has been supplied to form insoluble dietary fiber by the action of the alkali metal solution to obtain konjac powder.
(C) A washing step of washing the konjac powder.
(C') A neutralization step of neutralizing during the washing step or neutralizing the konjac powder that has undergone the washing step.
(D) A drying step of drying the konjac powder that has undergone the neutralization step.
As described above, the above steps (A) and (B) are performed until the konjac raw material powder loses its gelling ability while the powder particles contained in the konjac flour are maintained in the form of particles. .

The konjac powder thus obtained can be used as a raw material for food additives or a raw material for health foods.
In particular, the konjac flour according to the present invention has improved dispersibility in liquids containing water. , the particles mainly containing insoluble dietary fiber can spread quickly in a beverage or liquid food and keep the dispersed state for a long time. Furthermore, the particles mainly containing dispersed insoluble dietary fiber do not impede the smoothness of the beverage or liquid food, but rather have the effect of improving the smoothness. Therefore, konjac flour can be suitably used for easy intake of water-soluble fiber and insoluble dietary fiber from beverages and liquid foods, and is also suitable for mixing with sweets, bread, noodles and the like.
According to the method for producing konjac flour according to the present invention, the steps of preparing konjac paste, adding an alkaline coagulant and heating to gel the konjac paste, shredding and drying the konjac mass containing water, , It is possible to omit the step of powdering, and very efficiently produce konjac powder that has an increased proportion of insoluble dietary fiber and does not have gelling ability.

By converting water-soluble dietary fiber into insoluble dietary fiber, konjac powder with an increased content of insoluble dietary fiber can be used as a dietary fiber-enriched food itself, or as a food additive or supplement for enhancing dietary fiber in beverages and foods. Very useful as an ingredient.
The konjac powder obtained by the production method according to the present invention is extremely useful as a dietary fiber-enriched food itself such as a supplement, or as a dietary fiber-enriched food additive or auxiliary ingredient for beverages and foods.
When the konjac powder according to the present invention is used as a dietary fiber-enriched food, the konjac powder can be used as it is, or after being formulated with carriers, excipients, capsules, etc. that are acceptable as food ingredients. . Dietary fiber-enriched foods using konjac powder can be further blended with nutritional supplements such as vitamins, proteins, carbohydrates and minerals, if necessary.
When used as a food additive or auxiliary ingredient for beverages and foods, konjac powder can be used as it is, or after being formulated with carriers, excipients, capsule materials, etc. that are acceptable as food ingredients.

(Experimental example 1)
As refined konjac flour, TIMAC MANNAN (trade name) manufactured by Orihiro Co., Ltd. (water content 8.0% by mass, dietary fiber 85.4% by mass) was used.
Using sodium hydroxide (manufactured by Kanto Chemical Co., Ltd., food additive, purity 95%), A: 0.100 M (pH 13.0), B: 0.125 M (pH 13.1), C: 0.150 M ( pH 13.2), D: 0.200 M (pH 13.3), E: 0.300 M (pH 13.4) solutions were prepared.
After adding 15 g of sodium hydroxide solution to 10 g of timac mannan, homogenize using a cooking cutter (manufactured by Hitachi, model FV-F3), seal and heat at 60 ° C. for 30 minutes. C. for 20 hours. In this manner, 200 g of timac mannan as a raw material was used to prepare six types of test samples A to E having different alkali concentrations. An alcohol of 30% by mass, which is 8 times the amount of the raw material, was added to each material, neutralized with a citric acid solution, dehydrated, and dried at 70°C.
For each dry powder, water-soluble dietary fiber and insoluble dietary fiber were measured by moisture measurement and Prosky's modified method, and further mixed with water at 35 ° C. so that the solution concentration was 1% by mass to prepare a mixture. , the viscosity of each mixture was measured. This viscosity measurement method is generally used to determine the quality standard of konjac flour (water-soluble konjac flour). Machine Sangyo Co., Ltd., B-type viscometer) is measured, and the highest value among these is measured. The grading of konjac raw material powder is widely spread.
In one example of classifying the quality of konjac raw material powder based on this viscosity, those with a viscosity of 15,000 mPa s or more in this measurement method are classified as special powders, and those with a viscosity of 13,000 mPa s or more are classified as first class powders. . Timacmannan is treated with alcohol to remove the odor of trimethylamine, which is the odor of konjac, and has a high purification purity. there is
Table 1 shows the results.

(Experimental example 2)
100 g each of 0.2 M solution and 0.3 M solution of potassium hydroxide (manufactured by Kanto Chemical Co., Ltd., food additive, purity 85%) were added to each 100 g of timac mannan as a raw material, and mixed, It was homogenized using a cooking cutter, and test samples with two different alkali concentrations were prepared. After each was sealed and heated at 60° C. for 30 minutes, it was allowed to stand at 25° C. for 20 hours, and then dried at 75° C. so that the water content was 10% by mass or less. To this, 800 g of 30% by weight hydroalcohol was added, and 10% by weight citric acid solution was added to each to neutralize to pH 7.0. After dehydration, this was dried with hot air at 70°C. The moisture content of the dried product was 4.5% by mass for the sample adjusted with 0.2M potassium hydroxide solution and 7.1% by mass for the sample adjusted with 0.3M potassium hydroxide solution.
The amount of insoluble dietary fiber according to the Prosky modified method was 35.17% by mass and 38.51% by mass of water-soluble dietary fiber in the sample adjusted with 0.2M potassium hydroxide solution. The amount of insoluble dietary fiber relative to the amount of dietary fiber was 47.7% by mass. The sample prepared with 0.3M potassium hydroxide solution had an insoluble dietary fiber content of 80.0% by mass, a water-soluble dietary fiber content of 7.1% by mass, and an insoluble dietary fiber content of 91.0% with respect to the total dietary fiber content. It was 8% by mass.
When the viscosity of a 1 mass % solution of a sample prepared with a 0.2 M potassium hydroxide solution was measured at 35° C. every 2, 3, and 4 hours, the maximum value was 160.4 mPa·s. Further, when the viscosity of a 1% by mass solution of the sample prepared with a 0.3M potassium hydroxide solution was measured at 35° C. every 2, 3 and 4 hours, the maximum value was 4.0 mPa·s.
(Experimental example 3)
To 10 g of timac mannan as a raw material, 10 g of a 1 M solution (pH 11.7) of anhydrous sodium carbonate (manufactured by Kishida Chemical Co., Ltd., food additive, purity of 99% or more) is added and mixed, and using a cooking cutter Homogenized. After sealing and heating at 60° C. for 30 minutes, it was allowed to stand still at 35° C. for 20 hours. When 250 g of 30% by mass hydrous alcohol was added to this solution, the pH of the solution was 10.7. A 10% by mass citric acid solution was added to this to neutralize it to pH 7.0, and the same procedure as in Experimental Example 1 was followed to wash with 30% by mass alcohol, dehydrate, and dry at 75°C. The dry matter has a moisture content of 6.5% by mass, a water-soluble dietary fiber content of 3.3% by mass according to the modified Prosky method, and an insoluble dietary fiber content of 89.7% by mass. The amount amounted to 96.5% by weight.
(Experimental example 4)
After adding and mixing 15 g of a 0.4 M solution (pH 13.7) of potassium hydroxide (manufactured by Kanto Chemical Co., Ltd., food additive, purity 85%) to 10 g of timac mannan as a raw material, a cooking cutter (Hitachi The mixture was homogenized using a model FV-F3 manufactured by Seisakusho, sealed and heated at 60° C. for 30 minutes, and further heated at 30° C. for 15 hours. When 200 g of timac mannan was processed in this manner and 800 g of 30% by mass hydroalcohol was added thereto, the pH of the solution was 12.2. A 10% by mass citric acid solution was added to this to neutralize it to pH 7.0, and after stirring for 20 minutes, the mixture was allowed to stand, and the supernatant was discarded. Further, 800 g of 30% by mass hydroalcohol was added, stirred for 20 minutes, washed twice to discard the supernatant, dehydrated using a filter cloth, and dried with hot air at 70°C. The dry matter has a water content of 4.0% by mass, an insoluble dietary fiber content of 94.7% by mass according to the modified Prosky method, and a water-soluble dietary fiber content of 1.4% by mass. The amount amounted to 98.5% by weight.
(Experimental example 5)
As a raw material, 15 g of a 0.4 M solution (pH 13.5) of sodium hydroxide (manufactured by Kanto Chemical Co., Ltd., food additive, purity 95%) is added to 10 g of konjac powder / special powder (manufactured by Orihiro Co., Ltd.). After mixing, the mixture was homogenized using a mini speed mill (manufactured by Labonect Co., Ltd., model MS-05), sealed and heated at 60° C. for 30 minutes, and further heated at 35° C. for 20 hours. In this way, 200 g of special flour was processed, 800 g of 30% by weight hydroalcohol was added, 10% by weight citric acid solution was added to adjust pH to 6.90, stirred for 20 minutes, allowed to stand, and the supernatant was discarded. Further, 800 g of 30% by mass hydroalcohol was added and stirred for 20 minutes. After discarding the supernatant, dehydration was performed using a filter cloth. This was dried with hot air at 70° C., and water-soluble dietary fiber and insoluble dietary fiber were measured by Prosky's modified method.
As a result, the raw material special flour (water content 8.0% by mass) contained 75.6% by mass of water-soluble dietary fiber and 2.1% by mass of insoluble dietary fiber, and the ratio of insoluble dietary fiber to total dietary fiber is 2.7% by mass, whereas the dry matter (7.3% by mass of water) treated with 0.4M sodium hydroxide solution has 2.7% by mass of water-soluble dietary fiber and 2.7% by mass of insoluble dietary fiber. The ratio of insoluble dietary fiber to total dietary fiber was 97.1% by mass.
This powder is insoluble in water, and the measured value of the viscosity using a 1% by mass aqueous dispersion, which is a method for evaluating the quality of konjac flour (the viscosity is measured every 2, 3, and 4 hours while stirring in a warm bath at 35 ° C). Measured with a Brookfield viscometer, the maximum value during this period) was 2.0 mPa·s.

(Example 1)
As a raw material, 40 kg of timac mannan was put into a vertical granulator (manufactured by Powrex Co., Ltd., model FMVC-25) and stirred at 160 rpm. , food additives) was added and mixed for 40 minutes. It was taken out at a product temperature of 65° C., sealed, and held at room temperature for 20 hours. After drying this in an atmosphere of 70 to 80° C., 320 kg of 30% by mass hydrous alcohol was added and stirred for 20 minutes (pH 10.1). (The pH of the supernatant at this point is 6.98). After dehydration by filter cloth filtration and drying with hot air at 75° C., water-soluble dietary fiber and insoluble dietary fiber were measured by Prosky's modified method. As a result, the water content was 8.0%, the water-soluble dietary fiber was 2.3% by mass, the insoluble dietary fiber was 89.7% by mass, and the ratio of the insoluble dietary fiber to the total dietary fiber was 97.5% by mass. there were.
This powder was insoluble in water, and the value measured with a Brookfield viscometer after stirring for 3 hours in a 35° C. hot bath using a 1% by mass aqueous dispersion was 3.0 mPa·s. When this powder was pulverized (manufactured by Hosokawa Micron Corporation, model: ACM-15H), the minimum particle size was 4 μm, the maximum particle size was 296 μm, the d50 (median diameter) was 54 μm, and the water content was 4.5. 15.0% by mass of water-soluble dietary fiber and 79.4% by mass of insoluble dietary fiber measured by the modified Prosky method. When 2 g of this fine powder was slowly stirred for 15 minutes in 58 g of the disintegration test liquid 1 (0.29% hydrochloric acid solution: pH 1.2) at 35° C., water was incorporated into aggregates having a volume of 56 ml. became.

(Example 2)
As a raw material, 40 kg of timac mannan was put into a vertical granulator (manufactured by Powrex Co., Ltd., model FMVC-25) and stirred at 160 rpm. , food additives) was added and mixed for 40 minutes. The resulting mixture was taken out at a material temperature of 65° C., sealed, held at room temperature for 20 hours, and dried in an atmosphere of 70 to 80° C. to obtain 38.9 kg of dried product.
When the water-soluble dietary fiber and insoluble dietary fiber of this dry powder were measured by the modified Prosky method, it was found to be 7.3% by mass of water, 3.6% by mass of water-soluble dietary fiber, and 82.1% by mass of insoluble dietary fiber. . Moreover, the maximum value measured with a Brookfield viscometer after stirring for 3 hours in a 35° C. hot bath using a 1% by mass aqueous dispersion was 4.0 mPa·s.
320 kg of 30% by mass hydrous alcohol was added to the obtained dry powder, and after stirring for 20 minutes, 266 g of citric acid was added and dissolved, and wet grinder treatment was performed several times (pH of the supernatant at this point was 7.2). This was dehydrated by filtering with a filter cloth and dried with hot air at 75°C.
This dry powder was pulverized (manufactured by Hosokawa Micron Corporation, model: ACM-15H). The obtained konjac powder had a d50 (median diameter) of 40 μm. The minimum particle size was 2.9 μm and the maximum particle size was 230 μm. The pulverized konjac powder had a water content of 4.1% by mass, a water-soluble dietary fiber of 12.1% by mass and an insoluble dietary fiber of 82.3% by mass as measured by the modified Prosky method. Moreover, the maximum value measured with a Brookfield viscometer after stirring for 3 hours in a 35° C. hot bath using a 1% by mass aqueous dispersion was 17.5 mPa·s.
2 g of this fine powder was slowly stirred for 15 minutes in 58 g of disintegration test liquid 1 (0.29% hydrochloric acid solution: pH 1.2) at 35° C., resulting in a volume of 60 ml. When this solid fraction was observed with a stereomicroscope, a large number of small lumps in which konjac powder with water was associated were further associated with each other to form aggregates. It was confirmed that the konjac powder alone was hydrated.
One water-retained (swollen) konjac powder particle that swells by embracing this water and constitutes a small mass (for example, a cube with a length of 1100 μm and a width of 750 μm) taken out from the aggregate of the associated konjac flour. was typically 137×106 μm. On the other hand, 60 g of raw cabbage (edible part) was carefully ground into a paste with a food cutter (bamix-M300 manufactured by Cherry Terrace Co., Ltd.), and the volume of the ground product was approximately 60 ml. , the constituent cells were arranged three-dimensionally, and their sizes were approximately uniform, ranging from 100 to 130 μm in length×100 to 130 μm in width. From the above results, it was confirmed that this pulverized konjac flour absorbs water and exhibits a three-dimensional structure resembling the cells of raw vegetables.
This fine powder holds water (swells) in a temperature range from cold water to hot water, and each powder particle is associated with each other. . Therefore, if 2 to 8 g of the present konjac powder is added to hot miso soup or soup at each meal, the konnyaku powder quickly absorbs water and mixes, so that the konjac powder can be eaten with the same feeling as vegetable paste. That is, a dietary fiber paste having a ratio of water-soluble dietary fiber and insoluble dietary fiber close to that of vegetables and having water-holding capacity can be easily ingested.
In addition, the present konjac fine powder is sufficiently hydrated (swelled) in advance at a liquid temperature of about 70 ° C., and the taste such as fruit juice and flavoring are performed to make it a liquid state. After imparting viscosity, 4 to 6 g of this konjac fine powder per serving is packed in a container such as a standing pouch and sterilized, so that a food containing water-soluble dietary fiber and insoluble dietary fiber close to vegetables at any time. Fiber intake becomes possible.
After mixing 4 g of this konjac fine powder with one serving of powdered corn soup (18 g), 150 ml of hot water was poured and lightly stirred. 60 mass % or more of the corn soup that passed 100% remained on the 1.0 mm diameter sieve. As a result, the soup, which was normally drinkable, became an eating soup containing 3.6 g of dietary fiber.

Claims (13)

A method for producing konjac powder,
A supply step of adding an alkali metal solution to the refined konjac raw material and supplying the alkali metal solution to the powder particles contained in the refined konjac raw material ;
an insoluble dietary fiber forming step for obtaining konjac powder by forming insoluble dietary fiber in the powder particles supplied with the alkali metal solution by the action of the alkali metal solution,
The supplying step and the insoluble dietary fiber forming step are performed while the powder particles are maintained in the form of particles , and the konjac powder obtained by the insoluble dietary fiber forming step does not have gelling ability. A method for producing konjac powder, characterized by: 2. The method for producing konjac powder according to claim 1, wherein the ratio of insoluble dietary fiber to total dietary fiber contained in the konjac powder obtained by the insoluble dietary fiber forming step (based on mass) is 50% by mass or more. The method for producing konjac powder according to claim 1 or 2, wherein said insoluble dietary fiber forming step is a step of stirring and mixing powder particles supplied with said alkali metal solution. The method for producing konjac powder according to any one of claims 1 to 3, wherein the alkali metal solution contains an alkali metal compound of 0.1M to 5.0M. The method for producing konjac powder according to any one of claims 1 to 4, wherein the alkali metal compound contained in the alkali metal solution is at least one of a sodium compound and a potassium compound. The method for producing konjac powder according to claim 5, wherein the alkali metal compound is at least one of sodium hydroxide, potassium hydroxide and sodium carbonate. The method for producing konjac powder according to any one of claims 1 to 6, wherein the ratio (by mass) of the alkali metal solution to the refined konjac raw material is 0.1 to 10 times. The konjac powder according to any one of claims 1 to 7, wherein the konjac powder obtained by the insoluble dietary fiber forming step contains 99% by mass or less of insoluble dietary fiber (on a dry matter basis) relative to total dietary fiber. manufacturing method. The method for producing konjac powder according to any one of claims 1 to 8, wherein the supplying step and the insoluble dietary fiber forming step are performed simultaneously. The method for producing konjac powder according to any one of claims 1 to 9, comprising a step of washing the konjac powder obtained by the step of forming the insoluble dietary fiber . The method for producing konjac powder according to any one of claims 1 to 10, comprising a step of neutralizing the konjac powder obtained by the step of forming the insoluble dietary fiber . The method for producing konjac powder according to any one of claims 1 to 11, comprising a step of drying the konjac powder obtained by the step of forming the insoluble dietary fiber . 13. The method for producing konjac powder according to any one of claims 1 to 12, comprising a step of pulverizing the konjac powder obtained by the step of forming the insoluble dietary fiber .