JP7161210B2 - Food and its manufacturing method and agent - Google Patents

Description

TECHNICAL FIELD The present invention relates to a food, a method for producing the same, and an anti-obesity agent.

As a diet therapy for patients with renal disease, a low-protein diet therapy is performed in which foods with reduced protein content are ingested to reduce the burden on the kidneys. Since protein is contained in almost all food materials, it is necessary to pay close attention to the menu and the amount of food in order to limit its intake. In order to strictly follow the protein intake, it is necessary to determine the amount while weighing each ingredient, which imposes a great burden on patients and their families. In addition, the mental burden of not being able to eat the same food as the family is heavy. Not being able to enjoy meals greatly impairs the Quality Of Life.

As a food used in a low-protein diet, low-protein bread in which the protein content is reduced by replacing part or all of the raw material wheat flour with starch (JP 2015-033370, JP 2014-060945) No. and International Publication No. 2013/058309), and low-protein rice obtained by degrading the protein in rice using a protease or the like (International Publication No. 2017/037799, International Publication No. 2014/024642 and Patent Japanese Patent Application Laid-Open No. 2010-252714) and the like are being studied.

The standard for low-protein foods for special dietary uses approved by the Consumer Affairs Agency is that the protein content should be 30% or less of that of normal foods of the same kind. In addition, nephrologists and registered dietitians in charge of nutrition guidance have obtained hearing results that foods with a reduced protein content of 50% or less of the original content can be used as diet therapy.

However, these conventional low-protein foods have a reduced protein content, and are disadvantageous in that they lack good flavor compared to the original foods. Even rice and bread, which are staple foods, have this problem. Providing flavorful low-protein foods is a response to patients' earnest desires, and is of great social significance.

JP 2015-033370 A JP 2014-060945 A WO2013/058309 WO2017/037799 WO2014/024642 JP 2010-252714 A

The present invention has been made based on the circumstances as described above, and an object of the present invention is to provide a food in which digestion of protein is suppressed while maintaining good flavor.

As a result of intensive research to solve the above problems, the present inventors have found that by treating the protein contained in the food with tannin, it is possible to maintain the good flavor of the food while maintaining the digestion of the protein. can be suppressed, and completed the present invention.

An invention made to solve the above problems is a food containing a tannin-processed protein.

Another invention made to solve the above problems is a method for producing food, which includes a step of treating a protein-containing material with tannin.

Yet another invention made to solve the above problems is an anti-obesity agent containing a tannin-treated protein.

More specifically, the present invention relates to the following inventions and the like.
[1] A food containing tannin-treated protein.
[2] The food according to [1], wherein the tannin-treated product is a product obtained by immersing a protein-containing material in a tannin-containing liquid.
[3] The food according to [1] or [2], in which protein digestion is suppressed.
[4] The food according to any one of [1] to [3], in which the astringency of tannin is reduced.
[5] Any one of [1] to [4], wherein the processed tannin contains tannin and protein, and the ratio of tannin and protein is tannin/protein (mass ratio) = 0.08 to 0.6 Food as described.
[6] The food according to any one of [1] to [5], which is at least one selected from the group consisting of bread, udon, rice and meat.
[7] The food according to any one of [1] to [6], which is for kidney disease patients.
[8] A method for producing a food product, comprising the step of treating a protein-containing material with tannin.
[9] The method according to [8], wherein the tannin treatment is performed with a tannin-containing liquid.
[10] The method of [8] or [9], further comprising drying the protein-containing material before the tannin treatment step.
[11] An anti-obesity agent containing a tannin-treated protein.
[12] The agent according to [11], which is a food.

According to the food of the present invention, protein digestion can be suppressed while maintaining flavor. According to the food production method of the present invention, food having such excellent properties can be produced easily and reliably. The anti-obesity agent of the present invention can suppress weight gain by suppressing protein digestion. Therefore, these can be suitably used as foods for renal disease patients, obesity treatment, diet foods, and the like.

It is a graph which shows the relationship between the kind of processing liquid used in bread, and a digestibility. 4 is a graph showing the relationship between the concentration of tannic acid in bread and digestibility. It is a graph which shows the relationship between soaking time and digestibility in bread. 1 is a photograph of a cross-section of the internal phase of bread after tanning. Fig. 3 is a graph showing the reduction in digestibility by various persimmon tannins in bread. Fig. 2 is a graph showing digestibility reduction by tannin treatment with proanthocyanidins in bread. 4 is a graph showing the reduction in digestibility due to tannin treatment in udon. 4 is a graph showing the reduction in digestibility of freeze-dried cooked rice by tannin treatment. It is a graph which shows the relationship between the concentration of tannic acid and digestibility in the rice cooking which added tannic acid. Fig. 3 is a graph showing the reduction of digestibility by tannin treatment in chicken tenderloin.

<Food>
The food of the present invention contains tannin-treated protein. That is, the protein in the food is treated with tannin. The food may contain optional ingredients in addition to the tannin-processed protein. Each component will be described below.

[Tannin-treated product]
A “tannin-treated protein” refers to a product obtained by treating a protein with tannin. This protein is typically included in a protein-containing material. “Protein tannin treatment” refers to a treatment in which a protein is brought into contact with tannin, and is usually carried out by bringing a protein-containing material or the like into contact with a tannin-containing liquid.

(tannin)
“Tannin” refers to many plants, especially the bark of oak, oak, pine, acacia, mimosa, oak (fagaceae), leaves of goby, lourde, sumac (anacardiaceae), (Family) fruit, tamarind seed coat, chestnut skin, etc. It is a general term for complex aromatic compounds with many phenolic hydroxy groups that are widely distributed in the plant kingdom. The molecular weight of tannin is about 500 to about 30,000. Tannins react with metal salts and proteins to form precipitates. In addition, tannin presents a very strong astringent taste.

Tannins are roughly classified into hydrolyzable tannins and condensed tannins. Hydrolyzable tannins are hydrolyzed into polyhydric phenolic acids and polyhydric alcohols by acids, alkalis or enzymes. Examples of hydrolyzable tannins include gallotannins and ellagitannins. Gallotannins produce gallic acid by hydrolysis, and examples thereof include tannic acid. Tannic acid is a compound represented by the following formula (1) and is composed of sugar and gallic acid. As a raw material, quincunx from China, South Korea, and North Korea is mainly used, and it is obtained by extraction and refinement. Ellagitannins produce ellagic acid and sugars by hydrolysis. agrimonin, therimagrandin, casalictin, rugosin C, casarinin and the like. Condensed tannins include persimmon tannins and proanthocyanidins. Persimmon tannin is a polyphenol present in persimmons, and is a large condensate in which catechins are linked by intermolecular carbon-carbon bonds as represented by the following formula (2). Epicatechin, epigallocatechin, epicatechin gallate, and epigallocatechin gallate are known as constituent catechins. Proanthocyanidins refer to condensates of dimers or higher having a structure in which catechins are carbon-carbon bonded between the C-4 and C-8 positions. Proanthocyanidins include, for example, grape seed polyphenols, apple polyphenols, and the like.

In formula (2) above, R ₁ represents a hydrogen atom or a phenolic hydroxy group. _R2 represents a hydrogen atom or a galloyl group. n represents the number of repetitions and is an integer of 0-110.

As tannins, tannic acid, persimmon tannins or proanthocyanidins are preferred. Tannin does not include non-gallates such as catechin, gallocatechin, epicatechin and epigallocatechin; non-polymer catechins such as gallates such as epicatechin gallate and epigallocatechin gallate; and gallic acid.

The lower limit of the molecular weight of tannin is preferably 300, more preferably 500, and even more preferably 1000. The upper limit of the molecular weight of tannin is preferably 100,000, more preferably 50,000.

As a tannin, for example, persimmon tannin can be obtained by extracting persimmon fruit or the like with an ethanol solution or the like. In addition, tannin can be purified by, for example, treatment with a synthetic adsorbent, dialysis using a dialysis membrane, or the like. By performing dialysis using a dialysis membrane, low-molecular-weight portions below a certain molecular weight can be removed.

Methods for obtaining a tannin-treated protein include, for example, a method of contacting a protein-containing material with a tannin-containing liquid. Methods for contacting the protein-containing material with the tannin-containing liquid include, for example, a method of immersing the protein-containing material in the tannin-containing liquid, a method of coating the protein-containing material with the tannin-containing liquid, and a method of spraying the protein-containing material with the tannin-containing liquid. and the like. Among these, the method of immersing the protein-containing material in a tannin-containing liquid is preferred from the viewpoint of the efficiency of tannin treatment. A tannin-treated protein cannot be obtained by mixing a protein-containing material and tannin powder.

The tannin-treated product is preferably a product obtained by immersing a protein-containing material in a tannin-containing liquid.

By containing tannin-treated protein, the food maintains a good flavor and suppresses the digestion of the protein. In addition, the astringency of tannin is reduced.

Although it is not necessarily clear why the food having the above configuration provides the above effects, it can be inferred, for example, as follows. That is, a protein is transformed into something indigestible by digestive enzymes by tannin treatment, for example, by adsorption of tannin to the protein or coating of the molecular chain of the protein with the molecular chain of tannin. As a result, digestion of proteins in the food is suppressed. In addition, tannin is considered to suppress astringency when it is adsorbed or coated on protein. As a result, the food can maintain good flavor.

A tannin-processed product usually contains tannin and protein.

As the ratio of tannin and protein in the tannin-processed product, the lower limit of tannin/protein (mass ratio) is preferably 0.08, more preferably 0.15, still more preferably 0.25, and particularly 0.35. Preferably, 0.45 is more particularly preferred. The upper limit of tannin/protein (mass ratio) is preferably 1.0, more preferably 0.8, still more preferably 0.75, particularly preferably 0.7, particularly preferably 0.65, and 0.6. is most preferred. By setting the ratio of tannin to protein within the above range, digestion of protein can be further suppressed while maintaining good flavor. If the tannin/protein (mass ratio) is less than the above lower limit, digestion inhibition may be insufficient. If the tannin/protein (mass ratio) exceeds the above upper limit, the flavor may be impaired due to strong astringency.

The upper limit of protein digestibility in the food is preferably 70%, more preferably 60%, even more preferably 50%, and particularly preferably 30%. The lower limit of protein digestibility in the food is, for example, 0%, preferably 0.1%.

The digestibility of protein can be determined, for example, by decomposing the protein in foods with digestive enzymes and quantifying the amount of free amino acids produced.

The food may further contain optional ingredients such as carbohydrates, lipids, vitamins, minerals, water, etc., in addition to the tannin-treated protein.

Examples of food include bread, cake, cookies, udon, soba, ramen, pasta, rice (cooked rice), meat (including beef, pork, chicken, ham, sausage, etc.), fish meat (including squid, shrimp, etc.). ), eggs (including egg products), soybeans (including soybean products), and dairy products. Among these, at least one selected from the group consisting of bread, udon, rice and meat is preferred.

Since the digestion of protein is suppressed in the food, it is suitable for renal disease patients who have restricted protein intake. In addition, since the digestion of protein is suppressed in the food, it is possible to suppress the increase in body weight of humans, animals, etc., who eat the food, so that it can be suitably used as a food for treating obesity, dieting, etc. can be done.

<Food manufacturing method>
The food of the present invention can be produced, for example, by treating a protein-containing material with tannin.

The method for producing the food of the present invention includes a step of treating the protein-containing material with tannin (hereinafter also referred to as "tannin treatment step").

Protein-containing materials include, for example, foods containing protein. Foods containing protein include, for example, bread, cakes, cookies, udon, soba, ramen, pasta, rice, meat, fish, eggs, soybeans, and dairy products.

From the viewpoint of producing foods with good texture, it is preferable to use baked bread, boiled udon noodles, uncooked rice, or cooked rice as the protein-containing material.

The production method can further include a step of drying the protein-containing material (hereinafter also referred to as a "pre-drying step") before the tannin treatment step.

The production method includes, for example, a step of drying the protein-containing material after the tannin treatment step (hereinafter also referred to as a "post-drying step") after the tannin treatment step, and a step of drying the protein-containing material after the tannin treatment step after the tannin treatment step. A step of leaving (hereinafter also referred to as a “leaving step”) and the like can be included.
Each step will be described below.

[Pre-drying process]
In this step, the protein-containing material is dried before the tannin treatment step. By pre-drying the protein-containing material, the tannin treatment can be performed more effectively and protein digestion is more inhibited.

As a method for drying the protein-containing material, a wide range of known drying methods can be employed, for example, natural drying, air drying, hot air drying, heat drying, far infrared drying, reduced pressure/vacuum drying, freezing. A dry method (freeze-drying method) and the like can be mentioned. Among these, the freeze-drying method is preferred.

Protein-containing materials that are preferably pre-dried include, for example, cooked rice and meat, and freeze-dried cooked rice or freeze-dried chicken tenderloin is preferred.

[Tannin treatment process]
In this step, the protein-containing material is treated with tannin. As a result, a food or the like containing a tannin-treated protein can be obtained.

Examples of the method of tannin treatment include a method using a tannin-containing liquid.

Examples of methods using a tannin-containing liquid include a method of applying a tannin-containing liquid to a protein-containing material, a method of spraying a tannin-containing liquid onto a protein-containing material, a method of immersing a protein-containing material in a tannin-containing liquid, and the like. Among these, the method of immersing the protein-containing material in a tannin-containing liquid is preferred from the viewpoint of the efficiency of tannin treatment.

Examples of the method of immersion in the tannin-containing liquid include a method of putting the protein-containing material into a container containing the tannin-containing liquid.

The lower limit of the tannin concentration in the tannin-containing liquid is preferably 0.1 mg/mL, more preferably 1 mg/mL, still more preferably 2 mg/mL, and particularly preferably 5 mg/mL. The upper limit of the tannin concentration in the tannin-containing liquid is preferably 200 mg/mL, more preferably 100 mg/mL, still more preferably 50 mg/mL, and particularly preferably 20 mg/mL. Examples of the solvent in the tannin-containing liquid include water and alcohol. Among these, water is preferred.

Immersion in the tannin-containing liquid is usually performed at room temperature.

The lower limit of the immersion time is preferably 1 minute, more preferably 5 minutes, even more preferably 10 minutes, particularly preferably 20 minutes, particularly preferably 1 hour, and most preferably 2 hours. The upper limit of the immersion time is, for example, one day, preferably 12 hours.

After immersion, in order to remove tannin from the surface of the protein-containing material, it may be preferable to wash the material with water or the like.

[Post-drying process]
In this step, the protein-containing material after the tannin treatment step is dried. This makes it possible to more appropriately adjust the texture and the like of the food to be prepared.

Examples of the method for drying the protein-containing material after the tannin treatment step include a method of heat drying using a hot air dryer or the like, a method of vacuum drying using a vacuum dryer or the like, and the like.

The lower limit of the drying temperature is preferably 30°C, more preferably 45°C. The upper limit of the drying temperature is preferably 100°C, more preferably 70°C. The lower limit of the drying time is preferably 1 minute, more preferably 1 hour, and even more preferably 2 hours. The upper limit of the drying time is, for example, one day, preferably 12 hours.

The upper limit of the water content of the food after the post-drying step is preferably 75% by mass, more preferably 65% by mass. The lower limit of the moisture content of the food after the post-drying step is preferably 30% by mass, more preferably 35% by mass.

[Leave process]
In this step, the protein-containing material after the tannin treatment step is left to stand. If the tannin-treated protein-containing material is allowed to stand, the astringency may be further reduced.

The standing step is usually carried out by leaving the protein-containing material after the tannin treatment step in a container or in the atmosphere.

The lower limit of the leaving temperature is preferably 0°C, more preferably 3°C. The upper limit of the leaving temperature is preferably 35°C, more preferably 25°C.

The lower limit of the standing time is preferably 1 minute, more preferably 1 hour, still more preferably 12 hours, and particularly preferably 1 day. The upper limit of the leaving time is, for example, one week, preferably two days.

<Anti-obesity agent>
The anti-obesity agent of the present invention contains tannin-treated protein.

Since the anti-obesity agent suppresses the digestion of protein, it is possible to prevent obesity in humans, animals, etc. who have ingested this anti-obesity agent.

The anti-obesity agent may further contain, for example, carbohydrates, lipids, vitamins, minerals, water, etc. as optional ingredients in addition to the tannin-treated protein.

The anti-obesity agent may be a food.

The anti-obesity agent can be produced by the same method as the above-described method for producing the food.

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

<Preparation of persimmon tannin>
[Preparation Example 1]
Flat seedless persimmons harvested in late July (within 80 days after flowering) were used. 1 kg of the persimmon fruit with the calyx removed was cut into slices and dried at 60° C. for 20 hours using a far-infrared drier (manufactured by Vianobe) to obtain about 0.15 kg of dried persimmon fruit. This dried persimmon fruit was pulverized into powder using a mill mixer (manufactured by Osaka Chemical Co., Ltd.) to obtain dried persimmon powder.
10 g of dried persimmon powder was extracted with 300 mL of a 70% by volume ethanol solution at 80° C. for 30 minutes and centrifuged to obtain an extract and a residue. Next, 300 mL of 1% by volume concentrated hydrochloric acid (35% by mass)-70% by volume ethanol solution was added to the residue and extracted at 80° C. for 60 minutes. The resulting extract was concentrated using an evaporator. The bath temperature at the time of concentration was set at 80° C., and water was added at any time to concentrate without drying. Finally, ethanol was removed to obtain 150 mL of an aqueous oyster tannin (KT (Kaki-tannin)) solution. The persimmon tannin contained has a molecular weight distribution of 570 to 34,300 with a peak of 4,300.
The resulting KT aqueous solution had a pH of about 1.0. About 21 mL of 1N aqueous sodium hydroxide solution was added to 100 mL of this KT aqueous solution to prepare a neutralized solution (KT-neutralized solution) with a pH of 7.0. The KT aqueous solution contains 11 mg/mL of oyster tannin in terms of gallic acid, and the KT-neutralized solution contains 10 mg/mL of persimmon tannin.

Further, a purified persimmon tannin was prepared from the KT aqueous solution. An open column (inner diameter 25 mm, length 300 mm) was packed with about 80 mL of a synthetic adsorbent (Mitsubishi Chemical's "DIAION-HP20"), and an appropriate amount of KT aqueous solution was loaded therein. After washing with 300 mL of water, persimmon tannin was eluted with 300 mL of 50% by volume ethanol solution. After repeating this operation, the eluted liquid was concentrated by an evaporator (bath temperature 80° C.) and ethanol was removed to obtain 70 mL of an aqueous KT-purified (KT-P) solution. This liquid contains 13.8 mg/mL persimmon tannin.

In addition, the above-obtained 1% by mass concentrated hydrochloric acid (35% by mass)-70% by volume ethanol solution was extracted and applied to a dialysis membrane (RC dialysis tube Spectra/Pore 3, molecular weight cutoff 3500) to prepare a sample. . 200 mL of the extract was sealed in a dialysis membrane and dialyzed against water. The water was replaced appropriately and dialysis was performed for a total of 48 hours. 380 mL of the liquid in the dialysis tube was taken out and concentrated by an evaporator (bath temperature: 80° C.) to obtain 100 mL of KT-dialysate. This liquid contains 9.5 mg/mL persimmon tannin.

<Preparation of bread>
[Example 1]
The internal phase, which is the white part of bread (water content: about 43% by mass), was cut into 2 to 3 cm squares (thickness: 2 cm) and used as samples.
Also, an aqueous solution (6 mg/mL) of tannic acid (hereinafter referred to as "TA") (manufactured by Fuji Chemical Industry Co., Ltd., molecular weight: 1701) was prepared. 20 g of bread was soaked in 100 mL of TA aqueous solution for 2 hours. The water was then drained using a colander and the bread was placed in the dryer. A hot air dryer (manufactured by Maruyu Co., Ltd.) was used for drying under the conditions of 60° C. and 4 hours. During drying, the pan was turned over once every hour. The final moisture content was about 43% by weight.

Also, 20 g of bread was immersed in 100 mL of the KT-dialysis aqueous solution for 2 hours. After that, the water was drained using a strainer, and the bread was placed in a warm air dryer. The drying conditions were 60° C. and 4 hours.
In addition, 6 mg / mL gallic acid aqueous solution (Nacalai Tesque: 16533-24), 6 mg / mL catechin aqueous solution (Nacalai Tesque: 07425-24, D-(+)-catechin hydrate), 6 mg / mL Bread soaked in an aqueous solution of epigallocatechin gallate (Sigma-Aldrich: E4143-50MG) and 6 mg/mL of green tea extract (Maruzen Pharmaceutical Co., Ltd., green tea extract MF) was similarly prepared. The final moisture content of each bread was 49.5%, 48.3%, 47.0%, 49.2% by weight.
After the dried bread was pulverized with a coffee mill, it was used as a sample for the digestion experiment.

<Evaluation>
[Measurement of digestibility]
The digestibility was obtained by decomposing the protein with a digestive enzyme and quantifying the amount of free amino acids produced. Digestion experiments were performed by M. The method of Minekus et al. (Food Funct., 2014, 5, 1113-1124.) was partially modified.
Each sample corresponding to 0.25 g of the internal phase of bread was taken and placed in a centrifuge tube. 2.25 mL of SSF (Simulated Salivary Fluid, pH 7) solution, 6.25 μL of 0.3 M calcium chloride solution, and 244 μL of water were sequentially added thereto, and allowed to stand at room temperature for 2 minutes. Next, SGF (Simulated Gastric Fluid, pH 3) solution 1.875 mL, pepsin solution (18 mg/mL prepared by dissolving pepsin powder (Sigma-Aldrich: P7000, 284 U/mg) in SGF) 0.4 mL, 0 1.25 μL of 3M calcium chloride solution, 50 μL of 1N hydrochloric acid and 174 μL of water were added and shaken at 37° C. for 2 hours. A mini rotator ("ACR-100" by As One) was used for shaking, and an incubator ("IC101W" by Yamato Scientific Co.) was used for temperature control.

Then, 3.375 mL of SIF (Simulated Intestinal Fluid, pH 7) solution, pancreatin solution (prepared to 40 mg/mL by dissolving pancreatin powder (Sigma-Aldrich; P1750, 5 U/mg trypsin activity) in SIF) 1 0.25 mL, 10 μL of 0.3 M calcium chloride solution, 37.5 μL of 1N sodium hydroxide, and 327.5 μL of water were added and shaken at 37° C. for 2 hours.

In addition, samples were prepared by first washing the samples with SSF solution to remove the effects of free tannins. Washing was performed by adding 8 mL of SSF to a sample equivalent to 0.25 g of the internal phase of the bread, shaking and centrifuging, and removing the supernatant. This process was repeated three times. Digestion experiments were also performed on the treated samples.

The amounts of free amino acids in these digestive fluid samples were determined by the TNBS method as follows. Since the quantification by the TNBS method is proportional to the amino groups generated by the decomposition of protein by digestion, it is considered that free peptides are partly included in addition to the amount of free amino acids, but are treated as free amino acids here. Free amino acids react with TNBS (2,4,6-trinitrobenezenesulfonic acid) to develop a yellow color. Therefore, the amount of free amino acids can be determined from the absorbance. Here, the amino acid amount was determined from the absorbance at 420 nm.

The digested fluid sample was centrifuged (3000 rpm, 3 minutes) to obtain a supernatant. 650 μL of 10% (mass/volume) trichloroacetic acid was added to 650 μL of the supernatant and allowed to stand at room temperature for 10 minutes. After that, the supernatant was collected with a centrifuge. At this time, undegraded protein is removed as a precipitate. 200 μL of the supernatant was added to 2 mL of 0.2 M sodium borate buffer (pH 9.4), then 1 mL of 4 mM TNBS was added and left for 30 minutes. After that, 1 mL of 2 M sodium dihydrogen phosphate solution containing 18 mM sodium carbonate was added, and the absorbance at 420 nm was measured with a spectrophotometer ("U-3210" manufactured by Hitachi, Ltd.). This absorbance indicates the amount of free amino acids. For Blank, purified water was used instead of the digested sample.

Digestibility was obtained from the amount of free amino acids using the following formula (A). That is, the amount of digested free amino acids derived from tannin-treated bread was divided by the amount of digested free amino acids derived from bread not treated with tannins to obtain the digestibility (%).

n1: Amount of free amino acids in the system after digestion and deproteinization of tannin _- treated food (bread) n2: Amount of free amino acids derived from digestive enzymes _b : Free amino acids derived from tannin-treated food (bread) when not digested Amount (including amount of free amino acids derived from tannin (tannin extract) used for tannin processing)
N: Amount of free amino acids in the system after digestion and deproteinization of non-tannin-treated food (bread) B: Amount of free amino acids derived from non-tannin-treated food (bread) when not digested

The results are shown in FIG. 1, and the digestibility of the bread soaked in TA and KT dialysate and dried was suppressed to 14% and 15% of the control bread (without tannin treatment). This indicated that the protein in the bread became indigestible.
Inhibition of digestion was also confirmed in the washed samples, each of which had a digestibility of 10% or less of the control. This suggests that tannins interacting with proteins inhibited digestion, rather than free tannins contributing to digestion inhibition.

Inhibition of protein digestion leads to a reduction in the amount of protein that is digested and absorbed. Therefore, if digestion inhibition is read as reduction of protein content, a digestibility of 10% is equivalent to a protein content of 10% of the original amount of protein. That is, the digestibility of tannin-treated bread of 30% or less can be considered equivalent to the reduction of the protein content to 30% or less, which is the standard for low-protein foods indicated by the Consumer Affairs Agency.

On the other hand, gallic acid, which is a structural unit of tannic acid, and catechin, which is a structural unit of persimmon tannin, and epigallocatechin gallate, showed only slight inhibition of digestion. Furthermore, the same was true for green tea extracts containing each catechin.
In addition, all of the tannin-treated bread did not exhibit astringency, had a good flavor, and maintained the flavor of the bread. The TA pan was slightly brown and the KT-dialysis pan was red.

(Dependence of Tannic Acid Concentration on Digestibility)
TA aqueous solutions with concentrations of 1.5, 3, 6, 9, 11 and 15 mg/mL were prepared. Digestibility was determined for them. Digestion experiments were also carried out on those immersed in water instead of the TA aqueous solution.
In order to further remove the effects of free TA, samples were prepared by washing the samples with an SSF solution. Washing was performed by adding 8 mL of SSF to a sample equivalent to 0.25 g of the internal phase of the bread, shaking, centrifuging, and removing the supernatant. This operation was repeated three times.

The results are shown in FIG. The number after TA in FIG. 2 means the concentration (mg/mL) of the immersed TA aqueous solution. As the concentration of TA increased, the rate of inhibition of digestion also increased. This trend was also seen in the washed samples. It is considered that the digestibility was suppressed not by inhibition of digestive enzymes by free tannic acid, but by making the protein indigestible.
Bread treated with 1.5 to 11 mg/mL of TA aqueous solution exhibited almost no astringent taste, but bread prepared with 15 mg/mL exhibited astringent taste.

[Examination of immersion time]
The internal phase, which is the white portion of bread (water content: about 43% by mass), was cut into pieces of about 2 to 3 cm and used as samples. 20 g of bread was immersed in an aqueous TA solution (6 mg/mL) for 10, 30 and 120 minutes. The water was then drained using a colander and the bread was placed in the dryer. A hot air dryer (manufactured by Maruyu Co., Ltd.) was used for drying under the conditions of 60° C. and 4 hours. The final moisture content was about 45% by weight.
After the dried bread was pulverized with a coffee mill, it was used as a sample for the digestion experiment.
The results are shown in FIG. The digestibility for each immersion time was 10 minutes immersion: 45%, 30 minutes immersion: 35%, and 120 minutes immersion: 14%. In the case of bread, it was shown that the immersion time should be 10 minutes or more in order to obtain a digestibility of 50% or less.

[Evaluation of bread-making properties]
TA-soaked bread was prepared by immersing 100 g of the control bread made with the formulation shown in Table 1 in 500 mL of a 10 mg/mL TA aqueous solution and drying it.
Furthermore, the difference in bread characteristics between bread made by adding TA powder to raw materials such as wheat flour (TA mix) and bread made using TA-treated wheat flour (TA-treated flour) was evaluated.
TA-treated wheat flour is obtained by adding 2000 mL of 10.8 mg / mL TA aqueous solution to 360 g of hard flour, stirring for 2 hours, centrifuging and drying with a far infrared dryer (60 ° C., 12 hours). prepared.
The bread was baked using a home bakery ("SD-BMT2000" by Panasonic).

For the evaluation of bread properties, the bread internal phase was cut into 4 cm cubes and weighed. Also, the maximum load (g) and the area under the curve of load versus time (g·sec) were obtained from a compression test with a texture analyzer (“TA.XT.Plus” from Stable Micro Systems). The measurement was performed by using a cylindrical plunger (P/20) with a diameter of 2 cm and pushing 5 mm at 120 mm/min (trigger load: 0.049 N).
Also, the cross section of the internal phase of the bread was photographed (Fig. 4), and the ratio of the bubble area to the cross section of the bread was determined as the porosity by image processing. For image processing, photoshop (manufactured by Adobe) was used to collect color information of bubbles and determine their areas. The scale bar length in FIG. 4 is 1 cm.

Table 2 shows the results. There is almost no difference in the amount ratio of TA and protein (P) contained in each bread. Bread made with TA added during kneading (TA mix) and bread made with TA-treated wheat flour did not swell and became dumpling-like. When its properties were investigated, it was found that it was heavier than bread soaked and dried with control or tannic acid and lacked softness as bread. In addition, from the measurement of the texture analyzer, the bread soaked and dried with tannic acid had a smaller maximum load and a smaller product of load and time. This indicates that the bread soaked and dried with tannic acid is soft and has good texture. In addition, porosity also revealed that the bread soaked in tannic acid and dried had many air bubbles and was soft.

When actually eaten and sensed, the control and TA-immersed breads were soft and had good flavor. On the other hand, the bread made from the TA mix or the TA-treated wheat flour was hard and looked like a lump of wheat, had a salty taste, and could not be called bread. For this reason, simply mixing TA at the time of bread making or making bread using TA-treated wheat in advance does not produce bread and is not practical.

[Sensory evaluation of bread]
58 g of baguette (protein 9.1 g/100 g) cut into 3 cm-thick round slices was immersed in 300 mL of an 8 mg/mL TA aqueous solution. After 1 hour, the water was drained off, and dried in a hot air dryer at 50°C for 4 hours. As a result, a baguette with a reduced digestibility of 3% compared to the original baguette was prepared. This was used as a sensory sample. The sensory evaluation was carried out by 7 panelists by evaluating the flavor and astringency intensity in 3 grades according to the contents shown below.

A. Do you feel the flavor of bread? 3 You can feel the flavor of bread sufficiently 2 You can feel the flavor of bread, but not enough 1 You can not feel the flavor of bread

B. Do you feel the astringency of the bread? 3 Not much astringency 2 Astringency, but acceptable 1 Strong astringency

As a result, the average score for each evaluation was 2.9 points for flavor and 2.7 points for astringency. Do you get it.

[Bread sensory evaluation and statistical processing]
58 g of baguette (protein 9.1 g/100 g) cut into 3 cm-thick round slices was immersed in 300 mL of an 8 mg/mL TA aqueous solution. After 1 hour, the water was drained off, and dried in a hot air dryer at 50°C for 4 hours. As a result, a baguette with a reduced digestibility of 3% compared to the original baguette was prepared.
An untreated baguette (control) and a TA-treated baguette were used as sensory samples.

The sensory evaluation was carried out by 13 employees of Nakano BC (men and women in their 20s to 50s) who had undergone sensory training. The evaluation was performed by a scoring method, and the scoring scale was a 5-point system (-2 to +2). Evaluation items were flavor (-2: bad to +2: good) and astringency (-2: weak to +2: strong).
For statistical processing, a significant difference test (risk rate 5%) was performed by Wilcoxon signed rank sum test using add-in software Statcel4 (manufactured by OMS Publishing Co., Ltd.) for EXCEL.
Table 3 shows the results.

Flavor evaluation (mean value ± standard deviation value) was control: 0.5 ± 0.9, TA treatment: -0.1 ± 0.8. The evaluation of astringency was -0.2±0.9 for control and 0.2±0.8 for TA treatment. As a result of the test, no significant difference was found between the control and the TA treatment in both flavor and astringency. Therefore, it was found that this TA-treated bread retains the flavor of the bread, has an acceptable astringency, and is comparable to ordinary bread.
In addition, there was an opinion that the TA-treated bread had a less salty and natural flavor than the control. Therefore, a sample was prepared by adding 50 mL of water to 5 g of baguette pulverized by a mill, and the salt concentration of the supernatant was measured. As measured by a salt meter (“PAL-SIO” manufactured by Atago Co.), the results were control: 0.15% and TA treatment: 0.09%. From this, it became clear that the treated baguette had a low salt concentration. This is probably due to the fact that the salt was dissolved and removed when it was immersed in the TA aqueous solution. Considering it as a food for renal disease, low salt is desirable, and from that point of view it can be said to be an excellent food.

<Examination of suppression of bread digestion by various persimmon tannins>
20 g of bread was immersed in 100 mL each of the prepared KT solution, KT-neutralized solution, KT-P solution, and KT-dialysis solution for 2 hours. The water was then drained using a colander and the bread was placed in a drying cabinet. Air drying was performed at room temperature for 6 hours. The final water content was 40.1%, 41.9%, 36.4% and 45.0% by weight for KT, KT-neutralization, KT-P and KT-dialysis, respectively. Digestibility is shown in FIG. 5, and all of them were suppressed to 20%. As mentioned above, this is a digestion inhibition rate that corresponds to the reduction standard for low-protein foods (Consumer Affairs Agency).
Also, the color and taste of the bread were as follows: KT bread: red, slightly sour, KT-neutralized bread: brown, slightly salty, KT-P bread: brown, slightly sour, almost no astringency, KT-dialysis bread. : Reddish brown, no astringency, almost no effect on taste.

<Study of inhibition of digestion by proanthocyanidins>
As proanthocyanidins, grape seed polyphenol (manufactured by Sabinsa Japan Corporation, grape seed extract) and apple polyphenol (manufactured by Frontier Foods, apple polyphenol powder, derived from immature fruit) were used. 6 mg/mL and 12 mg/mL aqueous solutions of each were prepared.
The internal phase, which is the white portion of bread (water content: about 43% by mass), was cut into pieces of about 2 to 3 cm and used as samples. 20 g of bread was immersed in 100 mL of each liquid for 120 minutes. The water was then drained using a colander and the bread was placed in the dryer. A warm air dryer (manufactured by Maruyu Co., Ltd.) was used for drying under the conditions of 60° C. and about 4 hours. The final moisture content was about 47% by mass for grape seeds and 40% by mass for apples. After the dried bread was pulverized with a coffee mill, it was used as a sample for the digestion experiment.

The results are shown in FIG. The number after the sample name in FIG. 6 means the concentration (mg/mL) of the immersed aqueous solution. Grape seeds inhibited digestion in a dose-dependent manner. On the other hand, the digestibility of apples was about 60% at both concentrations. A similar tendency was observed for the washed sample.
Incidentally, tannin / protein (g / g), grape seed (6 mg / mL): 0.206 g / g, grape seed (12 mg / mL): 0.327 g / g, apple (6 mg / mL): 0.172 g /g, apple (12 mg/mL): 0.296 g/g.
However, this sample also contains polyphenols other than proanthocyanidins.

Both the grape seed and apple proanthocyanidin treated breads exhibited little astringency.
Thus, it was shown that tannins in the form of proanthocyanidins also suppress the digestion of proteins and can provide foods with good flavor.

<Preparation of Udon>
10 g of dried udon noodles (manufactured by Nakao Shokuhin Co., Ltd., protein content 8.8 g/100 g) were boiled in 200 mL of water for 5 minutes (this was used as a control). The drained noodles were immersed in 200 mL of an aqueous TA solution (6 mg/mL) for 2 hours to prepare tannin-treated udon. The final water content was Control: 58.8% by mass and TA treatment: 56.6% by mass.
9 mL of SSF was added to 3 g of this udon and homogenized to prepare a paste. 3 g of this paste was subjected to the digestion experiment. The following digestion experiments were performed in the same manner as described above.
In determining the digestibility, the difference due to the water content and the amount of tannin added was taken into consideration, and corrections were made so that the solutes derived from the udon noodles were equal.
A sample was also prepared by washing the prepared paste with SSF. (Washing was performed by adding 10 mL of SSF, shaking, centrifuging, and removing 10 mL of the supernatant, and this operation was performed three times.)

As a result, as shown in FIG. 7, the TA treatment was able to suppress the digestibility to 36%. In addition, the washing treatment was suppressed to 23% by TA immersion.
The TA-treated udon had little astringent taste and the flavor of the udon was preserved when the TA on the surface was washed away with water. When the treated udon was kept in a refrigerator (4°C) for one day, the astringency was almost eliminated. Moreover, even if it was soaked in hot water at 80° C. for 2 minutes and warmed, almost no astringency was felt.
The TA treatment caused the color to become slightly whiter, but not to the extent that it was noticeable.

<Preparation of cooked rice>
After removing 165 g of Koshihikari from Niigata Prefecture (manufactured by Itami Sangyo Co., Ltd.), it was immersed in 210 mL of water for 30 minutes. The rice was cooked in an electronic jar rice cooker (“SR-CL05P” by Panasonic) to obtain cooked rice.
173 g of cooked rice was freeze-dried using a freeze dryer (“FDU-2100” manufactured by Tokyo Rika Kikai Co., Ltd.) to obtain 104 g of freeze-dried (FD) rice. 37 mL of tannin aqueous solution was added to 32 g of FD rice. Here, the added amount of the tannin aqueous solution was set to be approximately the same as the amount of water reduced by freeze-drying. As the tannin aqueous solution, TA aqueous solution (15 mg/mL) and KT-dialysate were used. A control was prepared by adding 37 mL of water to 32 g of FD rice.
About 30 minutes after the addition of the aqueous tannin solution, the cooked rice had the same texture as before freeze-drying. This was used as tannin-treated cooked rice.

In addition, those treated with KT-dialysate exhibited a red color. However, it did not exhibit an astringent taste and had a good flavor. In addition, the astringent taste was reduced by refrigerating overnight at room temperature or at 4°C, even though it had an astringent taste immediately after the addition of the aqueous tannin solution.
The respective final water contents were Control: 59% by mass, TA: 55% by mass, and KT-dialysis: 53% by mass.
9 mL of SSF was added to 3 g of each cooked rice and homogenized using a homogenizer ("T10basic" from IKA) to prepare a paste. 2.5 g of the paste was subjected to digestion experiments. The following digestion experiments were performed in the same manner as described above. In determining the digestibility, the rice-derived solutes were corrected in consideration of the difference due to the amount of water and the amount of tannin added.
A sample was also prepared by washing the prepared paste with SSF. (Washing was performed by adding 10 mL of SSF, shaking, centrifuging, and removing 10 mL of the supernatant, and this operation was performed three times.)

The results are shown in FIG. Each tannin aqueous solution was able to suppress the digestibility to 30% or less. In addition, the same tendency was observed for the washed samples. As mentioned above, this also achieves a protein digestion inhibition rate equivalent to the low-protein food of the Consumer Affairs Agency.

[Sensory evaluation of cooked rice]
A sensory sample was prepared by adding 49 mL of a 15 mg/mL TA aqueous solution to 40 g of freeze-dried cooked rice. The sensory evaluation was carried out by five panelists by evaluating the flavor and astringency intensity in three grades according to the contents shown below.

A. Do you feel the flavor of rice? 3 Feel the flavor of rice sufficiently 2 Slightly inadequate, but feel the flavor of rice 1 Do not feel the flavor of rice

B. Do you feel the astringency of the rice? 3 Not much astringency 2 Astringency, but acceptable 1 Strong astringency

As a result, the average score for each evaluation was 2.8 points for flavor and 2.8 points for astringency. I found out.
Furthermore, even when the tannin-treated cooked rice was warmed in a microwave oven, it was not astringent and maintained its taste.

[Sensory evaluation and statistical processing of cooked rice]
A TA-treated sample was prepared by adding 50 mL of a 15 mg/mL TA aqueous solution to 40 g of rice obtained by cooking Koshihikari rice produced in Niigata Prefecture and freeze-drying the cooked rice, and leaving it in a refrigerator for one day. In addition, what was warmed with the microwave oven was used for the sensory test.
In addition, untreated cooked rice (control sample) and TA-added samples were prepared by adding 0.42 g/100 g of TA powder to this control sample and mixing them, and 3 kinds were sensory samples. Note that the TA-added sample contains half as much TA as the TA-treated sample.

The sensory evaluation was conducted by employees of Nakano BC (men and women in their 20s to 40s) who had undergone sensory training. Evaluation was done by a scoring system. The evaluation items were flavor (-2: bad to +2: good, 5-level scale, 14 people) and astringency (0: normal to +2: strong, 3-level scale (with the control sample as 0), 15 people). did.
Statistical processing was performed using EXCEL add-in software Statcel4 (manufactured by OMS Publishing Co., Ltd.), and multiple comparisons were performed by Tukey-Kramer method after one-way analysis of variance for flavor. Astringency was tested for significance by Wilcoxon signed rank sum test.

The flavor results are shown in Table 4 (average ± standard deviation). The TA-treated samples of the invention did not reach the control samples in average scores, but were found to be more palatable than the TA additions. As a result of the test, there was no significant difference between the control and the TA treatment, but a significant difference of 1% between the control and the TA addition, and a 5% significance between the TA treatment and the TA addition. There was no significant difference between control and TA treatment, indicating that the flavor was comparable.

The results regarding astringency are shown in Table 5 (mean value ± standard deviation value). The TA treated samples of the invention were found to be less astringent than the TA additions. Moreover, as a result of the test, a significant difference of 1% of the risk rate was obtained between the TA treatment and the TA addition. Also from this, the difference in astringency was clearly shown.

The TA-spiked sample contains only half the amount of TA as the TA-treated sample. When the same amount of TA as the TA-treated sample is added and mixed, the flavor is further reduced and the astringency is increased. Therefore, simply mixing TA does not provide a satisfying food product.
When the employees of Nakano BC (18 men and women in their 20s to 40s) were asked whether the TA-treated sample was acceptable as a daily meal, 89% answered that it was acceptable. Therefore, it is thought that even patients with renal disease can incorporate it as a dietary therapy on a daily basis.

<Cooked rice with tannic acid>
3 g, 4.5 g, and 6 g of tannic acid were dissolved in 210 mL of water to prepare each tannic acid aqueous solution. 165 g of Koshihikari produced in Niigata Prefecture (manufactured by Itami Sangyo Co., Ltd.) was rinsed with water and drained. Then, the rice was cooked in an electronic jar rice cooker (“SR-CL05P” by Panasonic) to obtain cooked rice (control was soaked in water instead of tannic acid).
The water content of each cooked rice was Control: 59% by mass, TA3g: 56% by mass, TA4.5g: 56% by mass, and TA6g: 53% by mass.
9 mL of SSF was added to 3 g of cooked rice and homogenized using a homogenizer (“T10basic” from IKA) to prepare a paste. 2.5 g of the paste was subjected to digestion experiments. The following digestion experiments are similar to those described above. In determining the digestibility, a correction was made so that the rice-derived solutes were equal. A sample was also prepared by washing the prepared paste with SSF. (Washing was performed by adding 10 mL of SSF, shaking, centrifuging, and removing 10 mL of the supernatant, and this operation was performed three times.)

The results are shown in FIG. The number after TA in FIG. 9 means the amount (g) of TA added. The digestibility was suppressed to 50% or less with the addition of 3 g of tannic acid, 30% or less with the addition of 4.5 g, and 0% with the addition of 6 g. In addition, the same trend was observed for the washed samples.
The astringent taste was also reduced in the one with 6 g added. In addition, the color was faintly reddish wine (especially the trace of germ was red). Some people who actually ate it favorably accepted this color as healthy food. In addition, there was also an opinion that the texture was strong.
From these results, it was shown that tannin-treated cooked rice is highly practical and can be incorporated into the diet of patients with kidney disease on a daily basis.

<Preparation of chicken fillet>
Tannin-treated chicken fillet was prepared by adding 60 mL of each of 87 mg/mL and 170 mg/mL TA aqueous solutions to 20 g of freeze-dried (FD) chicken fillet (for cats, manufactured by Mama Cook). Control was 20 g of fillet with 60 mL of water added. The respective final moisture contents were Control: 65% by mass, TA-87: 64% by mass, and TA-170: 53% by mass.
11 mL of SSF was added to 1 g of each chicken fillet and homogenized using a homogenizer ("T10basic" from IKA) to prepare a paste. 2.5 g of the paste was subjected to digestion experiments. A washed sample was also prepared by washing this paste with SSF to remove free TA. Subsequent digestion experiments were performed as described above. In determining the digestibility, a correction was made so that the solutes derived from fillet were equal.

The results are shown in FIG. The number after TA in FIG. 10 means the concentration (mg/mL) of the immersed TA aqueous solution. Digestibility was able to be suppressed to 50% or less also in chicken fillet.
The astringency of the treated chicken fillet was significantly reduced compared to the original tannin solution. When the processed product was placed in a refrigerator (4° C.) for one day, almost no astringency was felt. Moreover, even if it was warmed in a microwave oven, boiled, or baked, almost no astringency was felt.
In addition, although the color was slightly white, it did not significantly affect the quality.

[Amount of tannin adsorption]
The amount of tannin in the tannin solution after soaking was determined, and the amount of tannin adsorbed to the bread was determined from the difference from the amount of tannin in the original soaking liquid.
The amount of tannin was determined by the Foreign Ciocarte method. That is, 2400 μL of water, 150 μL of foreign cioccalt drug (Sigma-Aldrich, F9252-100ML), 450 μL of 20% (w/v) sodium carbonate were added to 30 μL of a measurement sample appropriately diluted with water, and mixed. 5 min in a hot water bath. Further, after incubation at room temperature for 15 minutes and homogenization, absorption at 765 nm was measured with a spectrophotometer ("U-3900" manufactured by Hitachi, Ltd.). A calibration curve was prepared with gallic acid (“16533-24” from Nacalai Tesque), and the amount of tannin was determined in terms of gallic acid.

The results are shown in T/protein (g/g) as the amount of tannin (T) adsorbed per 1 g of protein in bread. In TA, the adsorption amount increased in a concentration-dependent manner.
For cooked rice and tenderloin, the amount of tannic acid added was divided by the amount of protein in the food. Table 6 below shows the content of tannic acid relative to protein in bread, Table 7 shows the content of persimmon tannin relative to protein in bread, and Table 8 shows the content of tannin relative to protein in rice.

Tannin/protein (g/g) values for other foods are shown below.
Udon (immersed in TA 6 mg/mL): 0.363 g/g
Fillet (soaked in 87 mg/mL TA): 0.298 g/g
Fillet (soaked in TA 170 mg/mL): 0.565 g/g
Rice cooked with tannic acid solution (3 g added): 0.302 g/g
Rice cooked with tannic acid solution (4.5 g added): 0.447 g/g
Rice cooked with tannic acid solution (6 g added): 0.595 g/g

According to the food of the present invention, protein digestion can be suppressed while maintaining flavor. According to the food production method of the present invention, food having such excellent properties can be produced easily and reliably. The anti-obesity agent of the present invention can suppress weight gain by suppressing protein digestion. Therefore, these can be suitably used as foods for renal disease patients, obesity treatment, diet foods, and the like.

Claims (7)

A protein-containing food that has been immersed in a tannin-containing liquid having a tannin concentration of 1 mg / mL or more,
The protein digestibility is 70% or less of the protein-containing food that has not been immersed in a tannin-containing liquid.,
rice paddy For patients with kidney disease requiring restricted protein intake,as well as
The protein-containing food is at least one selected from the group consisting of bread containing baguette, boiled udon noodles, cooked rice or polished rice, and chicken fillet. A protein-containing food product characterized by: 2. The food according to claim 1, wherein the protein digestibility is 50% or less relative to the protein-containing food that has not been soaked in a tannin-containing liquid. The food according to claim 1 or 2, wherein the ratio of protein to tannin is a mass ratio of 0.08-1.0. Including a step of immersing the protein-containing food in a tannin-containing liquid having a tannin concentration of 1 mg / mL or more,as well as
The protein-containing food is at least one selected from the group consisting of bread containing baguette, boiled udon noodles, cooked rice or polished rice, and chicken fillet. characterized by
The protein digestibility is 70% or less relative to the protein-containing food that has not been immersed in a tannin-containing liquid, and
A method for producing a protein-containing food for renal disease patients who need to restrict protein intake. Including a step of immersing the protein-containing food in a tannin-containing liquid having a tannin concentration of 1 mg / mL or more,
The protein-containing food is at least one selected from the group consisting of bread containing baguette, boiled udon noodles, cooked rice or white rice, and chicken fillet; as well as
A method for producing a protein-containing food for kidney disease patients requiring restricted protein intake, comprising a step of drying the protein-containing food before and/or after the step of immersing the protein-containing food in a tannin-containing liquid. . 6. The method according to claim 4 or 5 , wherein the step of immersing in the tannin-containing liquid is performed for 10 minutes or longer. The method according to any one of claims 4 to 6 , characterized by comprising a step of drying the protein-containing food before the step of soaking the protein-containing food in the tannin-containing liquid.

Images