Edible bamboo powder, breeding suppression agent for clostridium bacteria formed of the same, immunostimulator, and production method of edible bamboo powder

Abstract

To provide a new food material formed of bamboo, by solving problems of a taste of bamboo and bacteria on bamboo, the bamboo having useful dietary fibers.SOLUTION: The invention is configured to: perform heat processing to ground products of stem parts of bamboo in a pressure reduction state, then select particles whose diameter is 200 μm or smaller, for acquiring bamboo powder, therefore the bamboo powder can be used as a food product without causing an improper taste such as bitterness of bamboo and astringency. By the pressure reduction heating processing, hard fibers of bamboo receive damage, and the fibers are converted into fibers with hardness suitable as food products, and useful components such as hemicellulose included in the dietary fibers, become in a state where the component can be easily used for a living body.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to edible bamboo powder, a growth inhibitor and immunostimulant for Clostridium bacteria comprising the same, and a method for producing edible bamboo powder. [Background technology]

[0002] Bamboo can grow even in wastelands or land unsuitable for agricultural crops, and grows so quickly that it can overgrow and cause damage to agricultural crops and fruit trees. Although there is a large amount of bamboo in Japan (estimated at 93 million tons), there are almost no industrial uses for it. Against this background, there was a time when it was considered to use bamboo as a biomass energy resource, but this has not been realized due to the disadvantages of bamboo, such as high energy conversion costs and low conversion efficiency. These disadvantages are due to some of the lignin decomposition products contained in bamboo inhibiting saccharification and alcohol conversion, and the concentrated sulfuric acid used in saccharification increasing equipment costs and processing costs. For this reason, in the academic field of biomass chemical conversion, research and development of advanced bamboo biomass utilization technology using biorefinery methods is being conducted at research institutes both in Japan and overseas.

[0003] As an example of such research and development, for example, Patent Document 1 proposes a silage body in which raw bamboo branches and leaves with an average crushing diameter of about 5 mm are mixed with raw bamboo stalk powder, and raw bamboo powder fermented feed is obtained by anaerobic fermentation using lactic acid bacteria derived from the raw bamboo branches and leaves. Also, Patent Document 2 proposes the preparation of a saccharified liquid useful as a raw material for bioethanol using cellulosic biomass as a raw material, although this is not limited to bamboo.

[0004] By the way, bamboo is a grass plant like wheat and rice, but it is a perennial plant with a life span of about 100 years. Bamboo can be eaten as bamboo shoots for a short period after it sprouts from the underground stem, but about one month later, the bamboo's vegetable fibers develop and it becomes a mature bamboo that does not break or fall even in strong winds. At this stage, it is no longer usable as food. Mature bamboo is not only fibrous and hard, but also has a unique bitter and astringent taste, and may sometimes be contaminated with microorganisms such as E. coli that may cause food poisoning, so even if the hardness can be overcome by crushing or other means, it is not suitable for consumption. Furthermore, for example, even if bamboo is powdered and mixed with wheat flour or the like to be secondary processed into bread, udon, confectionery, etc., the reducing substances contained in bamboo significantly hinder secondary processability.

[0005] On the other hand, dietary fiber such as hemicellulose contained in bamboo is considered to be promising, as it is believed to enhance the activity of intestinal bacteria and has immune activation effects (see, for example, Patent Document 3). However, as mentioned above, bamboo is not only hard, but also unsuitable for consumption due to issues such as its taste and bacterial contamination, so the road to practical use is not easy at present. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2010-81924 A [Patent Document 2] JP 2018-99082 A [Patent Document 3] JP 2020-117462 A Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made in consideration of the above circumstances, and aims to provide a new food material made from bamboo by solving problems such as the taste and bacteria of bamboo, which has useful dietary fiber. [Means for solving the problem]

[0008] As a result of intensive research into solving the above problems, the inventors discovered that the above problems could be solved by using bamboo powder obtained by heat-treating the crushed culm of bamboo under reduced pressure and selecting particles of 200 μm or less, and thus completed the present invention. Specifically, the present invention provides the following:

[0009] (1) The present invention relates to edible bamboo powder, characterized in that it contains bamboo powder obtained by heat-treating crushed bamboo culm material under reduced pressure and selecting particles of 200 μm or less.

[0010] (2) The present invention also relates to edible bamboo powder as described in (1), in which the heat treatment is microwave irradiation.

[0011] (3) The present invention also relates to edible bamboo powder according to item (1) or (2), characterized in that the heat treatment is carried out at 40 to 80° C. under a pressure of 16 kPa to 46 kPa.

[0012] (4) The present invention also relates to edible bamboo powder according to item (3), characterized in that the heat treatment is carried out at 55 to 65°C under a pressure of 16 kPa to 26 kPa.

[0013] (5) The present invention also relates to an inhibitor of the proliferation of bacteria of the genus Clostridium, comprising the edible bamboo powder according to any one of (1) to (4).

[0014] (6) The present invention also relates to an immunostimulant comprising the edible bamboo powder according to any one of (1) to (4).

[0015] (7) The present invention also relates to a method for producing edible bamboo powder, which comprises heat-treating crushed bamboo culm material under reduced pressure, selecting particles of 200 μm or less, and using these as the desired product.

[0016] (8) The present invention also relates to a method for producing edible bamboo powder as described in (7) above, in which the heat treatment is performed by microwave irradiation.

[0017] (9) The present invention also relates to a method for producing edible bamboo powder according to item (7) or (8), characterized in that the heat treatment is carried out at 40 to 80°C under a pressure of 16 kPa to 46 kPa.

[0018] (10) The present invention also relates to a method for producing edible bamboo powder as described in (9), characterized in that the heat treatment is carried out at 55 to 65°C under a pressure of 16 kPa to 26 kPa. Effect of the Invention

[0019] According to the present invention, the problems of taste and bacteria of bamboo, which has useful dietary fiber, are solved, and a new food material made from bamboo is provided. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The following describes an embodiment of the method for producing edible bamboo powder of the present invention, an embodiment of the edible bamboo powder, an embodiment of the growth inhibitor of Clostridium bacteria, and an embodiment of the immunostimulant. Note that the present invention is not limited to the following embodiments and aspects.

[0021] <How edible bamboo powder is produced> First, one embodiment of the method for producing edible bamboo powder of the present invention will be described. The method for producing edible bamboo powder of the present invention is characterized in that the crushed culm of bamboo is heat-treated under reduced pressure, and particles of 200 μm or less are selected and used as the target product. These items will be described below.

[0022] The bamboos used in the present invention include those that have a woody culm belonging to the Poaceae family of the Poales order, the Bambusoideae subfamily. In this respect, bamboos that do not have a woody culm are not suitable for use in the present invention. Bamboos have culms, branches, leaves, underground stems, and roots, and among these, the culm is a woody part that is divided into multiple parts by hard nodes that do not allow water to pass through and extends independently from the ground into the air, and corresponds to the trunk of a woody plant. Note that bamboos are generally considered to be not woody plants but grasses, and from this perspective, it is correct to treat the culm as a stem, and it may not be appropriate to consider the culm to be woody. However, the culm has the same hardness as the trunk of a woody plant and has many parts in common with the trunk of a woody plant in that it enables bamboo to stand on its own, so in the present invention, the culm is treated as being "woody". Examples of bamboo include Madake bamboo, Moso bamboo, Hachiku bamboo, Hoteichiku bamboo, Kikko bamboo, Horaichiku bamboo, and Narihiradake bamboo. Among these, Madake bamboo and Moso bamboo are preferable.

[0023] In the manufacturing method of the present invention, the bamboo culm is used in a crushed state. Specifically, the bamboo culm is used in a state in which it is crushed into fine particles by a crusher. The crusher used in this case can be, for example, a bamboo mill manufactured by Hokaku Alloy Manufacturing Co., Ltd., but is not particularly limited thereto. In the following description, the crushed bamboo culm is also simply referred to as "bamboo crushed material".

[0024] The bamboo crushed material is heat-treated under reduced pressure. This reduced pressure heat treatment can be called reduced pressure distillation of the bamboo crushed material, and by this treatment, components that give the bamboo crushed material unpleasant tastes such as bitterness and astringency, and reducing substances that hinder secondary processability are removed, and bacteria such as E. coli contained in the bamboo are killed. In addition, by this treatment, the bamboo's hard dietary fiber is damaged and converted into fiber with a hardness suitable for eating, and useful components contained in the dietary fiber such as hemicellulose are made more easily available to the living body.

[0025] To perform the reduced pressure heat treatment of the bamboo crushed material, the bamboo crushed material is placed in a distillation tank that can reduce pressure and liquefy and recover volatilized components, and the inside of the vacuum tank is reduced in pressure and the bamboo crushed material is heated while being stirred. The pressure and temperature at this time are preferably about 16 kPa to 46 kPa, which is close to vacuum, and about 40 to 80°C, and more preferably about 16 kPa to 26 kPa and about 55 to 65°C. By performing the reduced pressure heat treatment of the bamboo crushed material at such pressure and temperature, components that give unpleasant tastes such as bitterness and astringency, and reducing substances that inhibit secondary processability are efficiently removed from the bamboo crushed material, which is preferable. The reduced pressure heat treatment is performed until almost no distilled liquid is recovered from the bamboo crushed material. The distillation time at this time can be about 0.4 hours to 6 hours. The liquid recovered by the reduced pressure heat treatment is not used in the present invention, and the bamboo crushed material remaining in the distillation tank is used in the present invention.

[0026] When the bamboo pulverized material is subjected to reduced pressure heat treatment (i.e. reduced pressure distillation) as described above, microwave irradiation is a preferred method of heating the bamboo pulverized material. By heating the bamboo pulverized material by microwave irradiation while stirring, carbonization of the bamboo pulverized material can be suppressed and the irradiation process can be completed in a short time.

[0027] After the reduced pressure heat treatment, the crushed bamboo is selected for particles with a particle size of 200 μm or less and used as edible bamboo powder. However, particles with a particle size of more than 200 μm have a poor taste and are not used as edible bamboo powder. There are no particular limitations on the means for this particle size selection, but it is preferable to use a sieve that allows particles with a size of 200 μm or less to pass through.

[0028] The edible bamboo powder obtained through these processes has a good taste and can be mixed with wheat flour and other materials for secondary processing into bread, udon noodles, sweets, etc.

[0029] <Edible bamboo powder> Next, one embodiment of the edible bamboo powder of the present invention will be described. The edible bamboo powder of the present invention is characterized by containing bamboo powder obtained by heat-treating the crushed culm of bamboo under reduced pressure and selecting particles of 200 μm or less. In other words, the edible bamboo powder of the present invention is the same as the edible bamboo powder obtained by the above-mentioned edible bamboo powder manufacturing method. The edible bamboo powder of the present invention is obtained by heat-treating the culm of bamboo, which is a natural material, under reduced pressure and contains a wide variety of active ingredients. It is almost impossible or impractical to identify all of these various active ingredients, and therefore it can be said that there are impossible or impractical circumstances in which it is impossible or impractical to directly identify the edible bamboo powder of the present invention by its composition or characteristics.

[0030] The reduced pressure heat treatment is preferably carried out at about 40 to 80° C. under about 16 kPa to 46 kPa, which is close to a vacuum, and more preferably at about 16 kPa to 26 kPa and about 55 to 65° C. This heating is preferably carried out by irradiating with microwaves. These have already been described, and therefore will not be described here.

[0031] The edible bamboo powder of the present invention is free of the unpleasant tastes of bamboo, such as bitterness and astringency, and is free of the problem of contamination by bacteria such as E. coli. In addition, the hard bamboo fibers are damaged by the reduced pressure heat treatment, and are converted into fibers of a hardness suitable for eating, and the useful components contained in the dietary fiber, such as hemicellulose, become more easily available to the living body. Hemicelluloses contained in bamboos have an immunostimulating effect on the human body, as well as an effect of suppressing the growth of so-called bad bacteria, such as Clostridium bacteria, in the intestines. In addition, unlike the ground bamboo before the reduced pressure heat treatment, the edible bamboo powder of the present invention can be mixed with wheat flour and processed into bread, udon, confectionery, etc., and can be said to be useful for the development and production of foods with immunostimulating effects and intestinal environment-regulating effects.

[0032] <Growth inhibitor for Clostridium bacteria> The present invention also includes a growth inhibitor for Clostridium bacteria made from the edible bamboo powder of the present invention. As already mentioned, the edible bamboo powder of the present invention has the effect of suppressing the bad bacteria of the genus Clostridium in the intestines, so by utilizing this effect, the edible bamboo powder of the present invention can be used as a growth inhibitor for Clostridium bacteria.

[0033] <Immunostimulants> The above-mentioned immune stimulant made of the edible bamboo powder of the present invention is also one aspect of the present invention. The edible bamboo powder of the present invention has the effect of enhancing the immune system when administered to animals such as humans. Therefore, the immune stimulant of the present invention is considered to be effective against diseases that are often caused by a decrease in the body's immune system, such as malignant tumors (cancer), kidney disease, heart disease, myocardial infarction, chronic lymphocytic leukemia, hepatitis, chronic fatigue syndrome, cerebral thrombosis, dementia, chromosomal abnormalities, tumors, stomatitis, periodontal disease, various infectious diseases, poisonings (poisoning caused by Salmonella, Escherichia coli, Cryptosporidium, etc.), and various allergies.

[0034] Examples of applications of the immunostimulant of the present invention include medicines, veterinary drugs, animal feed additives, and foods and beverages with health uses such as foods for specified health uses and foods with functional claims, etc. When the immunostimulant of the present invention is a medicine or veterinary drug, examples of its dosage form include tablets, granules, pills, liquids, injections, and indwelling agents.

[0035] The edible bamboo powder of the present invention has been confirmed to have the effect of enhancing the phagocytic activity of macrophage cells, and based on this effect, it can be used as an immunostimulant. EXAMPLES

[0036] The present invention will be described in more detail below by way of examples, but the present invention is not limited to the following examples in any way.

[0037] [Preparation of bamboo powder 1] Five-year-old moso bamboo was pulverized using a bamboo mill manufactured by Hokaku Alloy Manufacturing Co., Ltd. to obtain pre-treated bamboo pulverized material. The obtained pre-treated bamboo pulverized material was then subjected to reduced pressure microwave treatment (i.e. reduced pressure heat treatment) using a product named EXT-V160PC6 manufactured by Kanematsu Engineering Co., Ltd. The conditions were reduced pressure of -80 kPa (pressure 21 kPa), heating temperature of 60°C, and treatment time of 40 minutes. The bamboo pulverized material after reduced pressure heat treatment was sieved using a sieve with a pore size of 200 μm, and those with pores of 200 μm or less were used as bamboo powder sample A, and those with pores of over 200 μm were used as bamboo powder sample B.

[0038] [Preparation of bamboo powder 2] The untreated bamboo powder obtained by the same procedure as above was subjected to reduced pressure microwave treatment (i.e. reduced pressure heat treatment) at a reduced pressure of -50 kPa (pressure 51 kPa), heating temperature of 85°C, and treatment time of 40 minutes. After reduced pressure heat treatment, the crushed bamboo material was sieved using a sieve with a pore size of 200 μm, and those with pores of 200 μm or less were designated as bamboo powder sample C, and those with pores of over 200 μm were designated as bamboo powder sample D.

[0039] [Preparation of bamboo powder 3] The untreated bamboo powder obtained by the same procedure as above was subjected to reduced pressure microwave treatment (i.e. reduced pressure heat treatment) under conditions of reduced pressure of -90 kPa (pressure 11 kPa), heating temperature of 35°C, and treatment time of 40 minutes. After reduced pressure heat treatment, the crushed bamboo material was sieved using a sieve with a pore size of 200 μm, and those with pores of 200 μm or less were designated as bamboo powder sample E, and those with pores of over 200 μm were designated as bamboo powder sample F.

[0040] [Taste evaluation] A sensory taste test was conducted by five panelists on seven samples of the untreated bamboo crushed material and bamboo powder samples A to F. The evaluation criteria were on a five-point scale as shown below, and the average scores given by the five panelists were calculated. The average scores were rounded off to the nearest whole number, and are shown in Table 1. The lower the average score shown in Table 1, the better the results. Rating 5: Strong feeling Rating 4: Feels somewhat strong Rating 3: Feel Rating 2: Somewhat felt Rating 1: Not felt

[0041] [Table 1]

[0042] Samples B, C, and F, which have particle sizes over 200μm, all had average evaluation points of 6 or more, indicating that they had poor taste. On the other hand, samples A, C, and E, which have particle sizes of 200μm or less, all had good taste, so it can be understood that bamboo powder with a particle size of 200μm or less is suitable for consumption. Furthermore, since the bamboo powder of sample A showed particularly good results, it can be understood that it is preferable to carry out the reduced pressure heating treatment under conditions of 16kPa to 46kPa and about 40 to 80℃.

[0043] [Evaluation of bacteria count and cyanide concentration] The moisture content, E. coli count, and cyanide concentration of each of the seven samples of pre-treatment bamboo crushed material and bamboo powder samples A to F were examined, and the results are shown in Table 2.

[0044] [Table 2]

[0045] As shown in Table 2, while cyanide was detected in the untreated ground material, it was found that cyanide was removed from samples A to F that had been subjected to reduced pressure heat treatment. It was also found that the reduced pressure heat treatment significantly reduced the number of E. coli bacteria, and that the reduced pressure heat treatment, especially when performed under conditions of 16 kPa to 46 kPa pressure and around 40 to 80°C, significantly reduced the number of E. coli bacteria.

[0046] [Secondary processability evaluation] A secondary processability evaluation was carried out for each of the untreated bamboo crushed material, the bamboo powder of sample A, and the bamboo powder of sample D. 10 parts by mass of the bamboo crushed material or bamboo powder to be tested and 100 parts by mass of auxiliary materials (butter, milk, etc.) were added to 100 parts by mass of weak wheat flour, and cookies were prepared according to the usual cookie preparation method. A sensory taste test was carried out for each of the prepared cookies by five panelists. The evaluation criteria were as follows: 5-point scale, and the average score given by the five panelists was calculated. The average score was rounded off to the nearest whole number, and is shown in Table 3. The smaller the average score shown in Table 3, the better the results. Rating 5: Strong feeling Rating 4: Feels somewhat strong Rating 3: Feel Rating 2: Somewhat felt Rating 1: Not felt

[0047] [Table 3]

[0048] As shown in Table 3, bamboo powder sample A, with a particle size of 200 μm or less, maintained a good taste even after being processed into cookies. On the other hand, bamboo powder sample D, with a particle size of over 200 μm, retained the poor taste derived from bamboo even after being processed into cookies. The product using bamboo powder sample A also had good processability.

[0049] [Clostridium growth inhibition test] The bamboo powder of sample A was examined for its growth inhibitory activity against Clostridium (Clostridium sporogenes, NBRC14293, NBRC). The GAM semi-fluid upper layer medium was weighed and dissolved in pure water to a specified concentration to prepare the medium. Next, 0.5 g of bamboo powder of sample A (final concentration 5%) was placed in a test tube, and 0.05 g of bamboo powder of sample A (final concentration 0.5%) was placed in a test tube, and the medium was dispensed into each of them. In addition, a test tube in which only the medium was dispensed was used as a control. After that, the medium in these three test tubes was sterilized in an autoclave, and after the temperature had dropped, the contents were mixed and solidified in a state in which the specimen was dispersed to a certain extent. Clostridium was added to the medium in each of the above three test tubes and cultured at 37°C for 26 hours.

[0050] The growth of the bacteria was measured as follows. First, the test tube in which the bacteria was cultured was slowly stirred to homogenize the medium. Next, the cultured medium was passed through a mesh with a mesh size of 40 μm to remove large particles. This was placed in a 96-well plate, and the absorbance was measured three times at a measurement wavelength of 600 nm, and the average value was calculated. The absorbance was also measured in the same manner for each sample-containing medium in which the bacteria was not seeded, and the measured value was used as the blank value. The measurement results are shown in Table 4. The p value in Table 4 was calculated by Student's t-test (two-tailed) with the control.

[0051] [Table 4]

[0052] As shown in Table 4, in the medium containing the bamboo powder of the present invention, the proliferation of Clostridium was inhibited in a concentration-dependent manner. This shows that the edible bamboo powder of the present invention has the effect of inhibiting the growth of so-called bad bacteria.

[0053] [Macrophage phagocytic activity test] A phagocytic activity test of macrophages (RAW264.7 cells) was conducted using bamboo powder (sample A) as a specimen. The RAW264.7 cells were subcultured in Dulbecco's modified Eagle's medium (DMEM) supplemented with 10% fetal bovine serum (FBS) at 37°C in a 5% carbon dioxide atmosphere. In the following, Dulbecco's modified Eagle's medium (DMEM) supplemented with 10% fetal bovine serum (FBS) is referred to as the growth medium. The bamboo powder specimens, sample A, were weighed out at 40 mg (concentration 1% when added to cells) and 20 mg (concentration 0.5% when added to cells), and each was added to 400 μL of growth medium containing an antibiotic, suspended thoroughly, and left to stand for 130 minutes for sterilization. The amount of antibiotic used was adjusted so that when added to the cells it would be at the antibiotic concentration used in normal culture. The mixture was then diluted to 2 mL with growth medium.

[0054] RAW264.7 cells were seeded in a 24-well plate at 2 x 104 cells / well and cultured overnight at 37°C in a 5% carbon dioxide atmosphere. After replacing the medium with 500 μL of fresh growth medium, inserts were placed in the wells, 500 μL of sterilized specimen was added to the inside of the insert, and cultured overnight at 37°C in a 5% carbon dioxide atmosphere. As a control, 500 μL of growth medium without specimen was added and cultured in the same manner. After removing the insert, contamination and cell survival were examined, and macrophage activity was measured for two high concentrations of specimens that were free of contamination and cytotoxicity. First, 100 μL of 2 × 107 beads / mL fluorescent latex beads were added to the cultured cells, and the cells were cultured for 2 hours at 37 ° C. under a 5% carbon dioxide atmosphere, and then rinsed three times with PBS to remove the remaining fluorescent latex beads. Next, the cells were collected from the cultured 24-well plate and precipitated by centrifugation, and then fixed with a 4% paraformaldehyde solution. After rinsing the cells twice with PBS to remove the fixative, the number of fluorescent latex beads present in the cells in the cell suspension was measured using a flow cytometer (Guava easyCyte HT system, easyCyte5HT, Luminex Corporation), and the percentage of phagocytosed cells and the number of particles phagocytosed by the cells were measured. The results are shown in Table 5. The p value in Table 5 was calculated by Student's t-test (two-tailed) with respect to the percentage (%) of phagocytosed cells and the control.

[0055] [Table 5]

[0056] As shown in Table 5, the phagocytic ability of macrophages cultured with the bamboo powder of the present invention was increased, indicating that the bamboo powder of the present invention has an immunostimulating effect.

Claims

1. This edible bamboo powder is characterized by comprising bamboo powder obtained by heat-treating crushed bamboo culm material under reduced pressure and selecting particles of 200 μm or less.

2. Edible bamboo powder according to claim 1, wherein the heat treatment is microwave irradiation.

3. Edible bamboo powder according to claim 1, characterized in that the heat treatment is carried out at 40 to 80°C under a pressure of 16 kPa to 46 kPa.

4. Edible bamboo powder according to claim 3, characterized in that the heat treatment is carried out at 55 to 65°C under a pressure of 16 kPa to 26 kPa.

5. A growth inhibitor for Clostridium bacteria comprising the edible bamboo powder according to any one of claims 1 to 4.

6. An immunostimulant comprising the edible bamboo powder according to any one of claims 1 to 4.

7. A method for producing edible bamboo powder, comprising heat-treating crushed bamboo culm material under reduced pressure, and selecting particles of 200 μm or less to be used as the desired product.

8. A method for producing edible bamboo powder as described in claim 7, wherein the heat treatment is microwave irradiation.

9. The method for producing edible bamboo powder according to claim 7, characterized in that the heat treatment is carried out under a pressure of 16 kPa to 46 kPa at a temperature of 40 to 80°C.

10. The method for producing edible bamboo powder according to claim 9, characterized in that the heat treatment is carried out at 55 to 65°C under a pressure of 16 kPa to 26 kPa.

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