Method for producing modified starch food

Abstract

The present invention provides a starch food for which aging is suppressed.　Provided is a method for producing a starch food, the method comprising adding (1) maltotriosyl transferase, (2) a mineral or a salt thereof selected from calcium and magnesium, and (3) water to a starch food raw material. The mineral or a salt thereof in (2) is added in an amount that, if dissolved in the water in (3), makes a solution having a concentration of 0.15 mM to 75 mM. Also provided is a method for suppressing aging of starch foods. Further provided is an enzyme preparation that contains maltotriosyl transferase and a mineral selected from calcium and magnesium or a salt thereof.

Description

Method for producing modified starch foods

[0001] The present invention relates to a method for producing modified starch foods, a method for modifying starch foods, and an enzyme preparation for modifying starch foods.

[0002] Food raw materials containing starch, such as raw rice and wheat flour, undergo gelatinization (gelatinization) when heated in the presence of water, becoming starch foods suitable for human consumption (e.g., cooked rice, pasta, bread). However, starch foods undergo beta-stage (aging) over time, resulting in a deterioration in taste and texture. Therefore, there is a need for the development of starch foods that can suppress aging. Furthermore, starch foods tend to increase blood glucose levels after meals, which can lead to obesity and diabetes, so there is a need for the development of starch foods that can suppress the increase in blood glucose levels after meals.

[0003] Patent Document 1 discloses a method for producing glycosides, characterized by a step of reacting a specific maltotriosyltransferase with a donor substrate in the presence of an acceptor substrate. Patent Document 2 discloses a method for producing cooked rice foods and the like that suppress the rise in blood glucose levels, including a step of adding exoamylase and 4-α-glucanotransferase to raw rice. However, it was not previously known that a starch food with suppressed retrogradation could be produced by reacting a starch food raw material with a specific enzyme described in the present invention, which will be described later, in combination with a specific mineral or a salt thereof. Furthermore, it was not previously known that a starch food that is imparted with resistance to digestion and that can suppress the rise in postprandial blood glucose levels could be produced by reacting a starch food raw material with a specific two enzymes described in the present invention, which will be described later, in combination with a specific mineral or a salt thereof.

[0004] JP 2019-115361 A International Publication No. 2021 / 210626

[0005] A first object of the present invention is to provide a starch food that is inhibited from retrograding. A second object of the present invention is to provide a starch food that is imparted with resistance to digestion and that can inhibit an increase in blood glucose level after eating.

[0006] The present inventors conducted extensive research to solve the above-mentioned problem (aging) and found that starch foods with inhibited aging can be produced by allowing a combination of maltotriosyltransferase (hereinafter sometimes referred to as "MTT") and a mineral selected from calcium and magnesium or a salt thereof to act on starch food raw materials. Based on this finding, the present inventors conducted further research and completed the present invention (first invention). Furthermore, the present inventors conducted extensive research to solve the above-mentioned problem (postprandial rise in blood glucose levels) and found that a combination of two enzymes (i.e., maltotriosyltransferase and α-glucosidase (hereinafter sometimes referred to as "AG")) and a mineral selected from calcium and magnesium or a salt thereof to act on starch food raw materials can impart digestibility to starch foods and produce starch foods that can inhibit postprandial rise in blood glucose levels. Based on this finding, the present inventors conducted further research and completed the present invention (second invention).

[0007] That is, the present invention (Invention 1) provides the following: [1] A method for producing a starch food, comprising adding to a starch food raw material: (1) maltotriosyltransferase, (2) a mineral selected from calcium and magnesium or a salt thereof, and (3) water, wherein the amount of the mineral or salt thereof added in (2) is such that when it is dissolved in the water (3), it will have a concentration of 0.15 mM to 75 mM in the solution. [2] The production method described in [1] above, wherein the starch food raw material is raw rice, and the starch food is cooked rice. [3] A method for inhibiting retrogradation of a starch food, comprising adding to the starch food raw material: (1) maltotriosyltransferase, (2) a mineral selected from calcium and magnesium or a salt thereof, and (3) water, wherein the amount of the mineral or salt thereof added in (2) is such that when it is dissolved in the water (3), it will have a concentration of 0.15 mM to 75 mM. [4] The method for inhibiting aging according to [3] above, wherein the starch food raw material is raw rice and the starch food is cooked rice. [5] An enzyme preparation containing maltotriosyltransferase and a mineral selected from calcium and magnesium or a salt thereof. [6] The enzyme preparation according to [5] above, which is added to a starch food raw material to inhibit aging of the starch food. [7] The enzyme preparation according to [6] above, wherein the starch food raw material is raw rice and the starch food is cooked rice.

[0008] The present invention (Invention 2) also provides the following: [1'] A method for producing a starch food, comprising adding to a starch food raw material: (1) maltotriosyltransferase and α-glucosidase, (2) a mineral selected from calcium and magnesium or a salt thereof, and (3) water, wherein the amount of the mineral or salt thereof added in (2) is such that when dissolved in the water in (3), the concentration in the solution becomes 0.15 mM to 75 mM. [2'] The production method according to [1'] above, wherein the starch food raw material is raw rice, and the starch food is cooked rice. [3'] A method for imparting digestibility to a starch food, comprising adding to a starch food raw material: (1) maltotriosyltransferase and α-glucosidase; (2) a mineral selected from calcium and magnesium or a salt thereof; and (3) water, wherein the amount of the mineral or salt thereof added in (2) is such that when dissolved in the water in (3), the concentration in the solution becomes 0.15 mM to 75 mM. [4'] A method for inhibiting aging according to the above [3'], wherein the starch food raw material is raw rice and the starch food is cooked rice. [5'] An enzyme preparation containing maltotriosyltransferase, α-glucosidase, and a mineral selected from calcium and magnesium or a salt thereof. [6'] The enzyme preparation according to the above [5'], for adding to a starch food raw material to impart digestibility to the starch food. [7'] The enzyme preparation according to the above [6'], wherein the starch food raw material is raw rice and the starch food is cooked rice.

[0009] According to the present invention (Invention 1), a starch food with inhibited retrogradation can be produced by allowing a starch food raw material to react with a combination of maltotriosyltransferase and a mineral selected from calcium and magnesium or a salt thereof. Furthermore, according to the present invention (Invention 1), a method for inhibiting retrogradation of starch foods and an enzyme preparation capable of inhibiting retrogradation of starch foods can be provided.

[0010] According to the present invention (Invention 2), by allowing a combination of two enzymes (maltotriosyltransferase and α-glucosidase) and a mineral selected from calcium and magnesium or a salt thereof to act on a starch food raw material, it is possible to impart digestibility to the starch food and produce a starch food that can suppress a rise in blood glucose level after eating. Furthermore, according to the present invention (Invention 2), it is possible to provide a method for imparting digestibility to starch foods and an enzyme preparation that can impart digestibility to starch foods.

[0011] The first aspect of the present invention will be described in detail below. The method for producing a starch food of the present invention (first aspect) comprises adding (1) maltotriosyltransferase, (2) a mineral selected from calcium and magnesium or a salt thereof, and (3) water to a starch food raw material, wherein the amount of the mineral or salt thereof added in (2) is such that when dissolved in the water in (3), the concentration in the solution becomes 0.15 mM to 75 mM.

[0012] Maltotriosyltransferase (EC 2.4.1.25) is an enzyme that acts on polysaccharides and oligosaccharides having an α-1,4 glycosidic bond as a linkage mode, transferring maltotriose units to saccharides. The enzymatic activity of the maltotriosyltransferase used in the present invention can be measured by a 4-α-glucanotransferase activity test, and 1 U (unit) is defined as the amount of enzyme that purifies 1 μmol of glucose from maltotetraose per minute after a 60-minute reaction at pH 6.5 and 40°C. Examples of maltotriosyltransferase include enzymes commercially available from Amano Enzyme Co., Ltd. under the trade names "Glycotransferase" and "Glycotransferase 'Amano' L."

[0013] In the present invention (Invention 1), the amount of maltotriosyltransferase added per 1 g of starch food raw material is preferably 0.01 U or more, more preferably 0.02 U or more, even more preferably 0.05 U or more, and particularly preferably 0.1 U or more, 0.5 U or more, 1 U or more, 2 U or more, 3 U or more, 4 U or more, 5 U or more, or 6 U or more. In the present invention (Invention 1), the amount of maltotriosyltransferase added per 1 g of starch food raw material is preferably 100 U or less, more preferably 75 U or less, even more preferably 50 U or less, 40 U or less, 30 U or less, 25 U or less, 20 U or less, 15 U or less, 10 U or less, 9 U or less, or 8 U or less in terms of enzyme activity. In the present invention (first invention), the amount of maltotriosyltransferase added is preferably 0.01 U or more, more preferably 0.02 U to 100 U, even more preferably 0.05 U to 75 U, and particularly preferably 0.1 U to 50 U, 1 U to 25 U, 2 U to 20 U, 3 U to 15 U, 4 U to 10 U, 5 U to 9 U, or 6 U to 8 U in terms of enzyme activity per 1 g of starch food raw material.

[0014] The reaction time of maltotriosyltransferase is not particularly limited as long as it is a time that allows the enzyme to act on the substrate substance, starch, but a practical reaction time is preferably 1 to 100 minutes, more preferably 10 to 50 minutes. The reaction temperature is also not particularly limited as long as it is within a range in which the enzyme maintains its activity, but a practical temperature range of 5 to 80°C is preferred. The enzymatic reaction can be terminated, for example, by heating at 90 to 100°C for 1 to 30 minutes.

[0015] The manufacturing method of the present invention (first invention) is characterized in that "(2) a mineral selected from calcium and magnesium or a salt thereof" is added to a starch food raw material together with maltotriosyltransferase. In the present invention, the calcium salt includes an inorganic salt of calcium or a salt of calcium with an organic acid, such as calcium chloride (CaCl ２ In the present invention, examples of magnesium salts include inorganic salts of magnesium and salts of magnesium with organic acids, such as magnesium chloride (MgCl２ ) are listed.

[0016] In the production method of the present invention (Invention 1), the amount of (2) mineral or its salt added to the starch food raw material is such that, when dissolved in water (3), the concentration of (2) mineral or its salt in the solution is 0.15 mM or more, preferably 0.2 mM or more, 0.25 mM or more, 0.3 mM or more, more preferably 0.35 mM or more, even more preferably 0.4 mM or more, still more preferably 0.45 mM or more, and particularly preferably 0.5 mM or more. In the production method of the present invention (Invention 1), the amount of (2) mineral or its salt added to the starch food raw material is such that, when dissolved in water (3), the concentration of (2) mineral or its salt in the solution is 75 mM or less, preferably 70 mM or less, more preferably 65 mM or less, even more preferably 60 mM or less, still more preferably 55 mM or less, and particularly preferably 50 mM or less. In the production method of the present invention (Invention 1), the amount of (2) mineral or a salt thereof added to the starch food raw material is such that when dissolved in (3) water, the concentration of (2) mineral or a salt thereof in the solution is preferably 0.2 mM to 70 mM, 0.25 mM to 70 mM, 0.3 mM to 70 mM, more preferably 0.35 mM to 65 mM, even more preferably 0.4 mM to 60 mM, still more preferably 0.45 mM to 55 mM, and particularly preferably 0.5 mM to 50 mM. In this specification, "mM" means "mmol / L."

[0017] In the production method of the present invention, the time and temperature for the action of the mineral or salt thereof (2) can be the same as those for the action of the maltotriosyltransferase described above.

[0018] In the production method of the present invention, the amount of water (3) added varies depending on the type of starch food, but is generally, for example, 5 to 200 parts by weight, preferably 10 to 180 parts by weight, and more preferably 20 to 170 parts by weight, relative to 100 parts by weight of the starch food raw material. In the production method of the present invention, when the starch food raw material is raw rice (the starch food is cooked rice), the amount of water (3) added is, for example, 50 to 200 parts by weight, preferably 70 to 180 parts by weight, and more preferably 90 to 170 parts by weight, relative to 100 parts by weight of the raw rice. In the production method of the present invention, when the starch food raw material is wheat flour (the starch food is bread), the amount of water (3) added is, for example, 20 to 200 parts by weight, preferably 30 to 180 parts by weight, and more preferably 40 to 150 parts by weight, relative to 100 parts by weight of wheat flour. In the production method of the present invention, when the starch food raw material is wheat flour (the starch food is pasta), the amount of water (3) added is, for example, 5 to 100 parts by weight, preferably 10 to 90 parts by weight, and more preferably 15 to 80 parts by weight, per 100 parts by weight of wheat flour.

[0019] In the present invention (first invention), the "starch food raw material" to which the above-mentioned enzymes and minerals are added refers to a food raw material containing starch. In the present invention, examples of the "starch food raw material" include raw rice and wheat flour.

[0020] In the manufacturing method of the present invention, the raw rice used as a raw material is not particularly limited in terms of rice variety or whether it has been polished or not, and examples include polished rice, brown rice, germinated brown rice, high-amylose rice, and low-amylose rice.

[0021] The manufacturing method of the present invention (Invention 1) is specifically described below for the case where the starch food raw material is raw rice and the starch food is cooked rice. In the present invention, the rice cooking step preferably includes a step of raising the temperature from room temperature to 100°C after adding the enzymes and minerals, preferably over 5 to 60 minutes, more preferably 10 to 50 minutes, even more preferably 10 to 30 minutes, and even more preferably about 10 minutes, taking into account the enzyme reaction time. Upon reaching 100°C, the enzymes are inactivated and the enzymatic reaction is terminated. This is usually followed by a continuous boiling step (e.g., 15 to 30 minutes, preferably about 15 to 20 minutes) and a steaming step (e.g., 10 to 40 minutes, preferably about 10 to 20 minutes), to produce the improved cooked rice of the present invention (cooked rice with inhibited aging). In the present invention, the rice cooking step is carried out for, for example, 3 hours or less, preferably 2 hours or less, and more preferably about 1 hour (about 50 to 60 minutes) after adding the enzymes and minerals. The present invention is advantageous in that the effect can be obtained even if the rice cooking step is completed in a short time (for example, about 1 hour) after the addition of the enzyme. In the present invention, the rice cooking step may be performed using a commercially available rice cooker. The production method of the present invention may include steps other than the above steps (for example, a drying step, a freeze-drying step) as long as the effect of the present invention is not impaired.

[0022] The production method of the present invention (first invention) makes it possible to produce modified starch foods (particularly starch foods in which retrogradation is inhibited). In the present invention, "retrogradation of starch foods" refers to the beta transformation of starch foods over time, resulting in a deterioration in the taste and texture of the starch food (for example, in the case of cooked rice, the loss of desired softness, stickiness, palatability, etc., and the development of undesirable powdery texture and off-flavor; in the case of bread, the loss of desired softness, stickiness, palatability, etc., and the development of undesirable powdery texture). In the present invention, "inhibition of retrogradation of starch foods" refers to the inhibition (improvement) of retrogradation (deterioration of taste and texture) of starch foods compared to starch foods produced without the addition of the enzymes and minerals of the present invention.

[0023] In the present invention, "starch food" refers to a food containing starch. Examples of "starch food" in the present invention include cooked rice or cooked rice foods (e.g., cooked rice (white rice, brown rice, germinated brown rice, high-amylose rice, low-amylose rice, rice with added barley, rice with added glutinous barley, rice with added miscellaneous grains, rice with added resistant carbohydrates), vinegared rice (sushi rice), red rice, pilaf, fried rice, seasoned rice, steamed sticky rice, rice balls, sushi, boxed lunches), processed rice products (e.g., rice crackers, rice crackers, Japanese sweets, rice cakes), bread, and pasta.

[0024] In this specification, the term "food" is a concept that broadly encompasses anything that can be taken orally (excluding pharmaceuticals), and includes not only so-called "foods" but also beverages, health supplements, health functional foods (e.g., foods for specified health uses, foods with functional claims, foods with nutrient functions), supplements, etc.

[0025] One aspect of the present invention (Invention 1) relates to a method for inhibiting retrogradation of starch foods, which comprises adding to a starch food raw material: (1) maltotriosyltransferase; (2) a mineral selected from calcium and magnesium or a salt thereof; and (3) water, wherein the amount of the mineral or salt thereof added in (2) is such that when dissolved in the water in (3), the concentration in the solution becomes 0.15 mM to 75 mM. In the method for inhibiting staling of starch foods of the present invention, the definition, amount to be added, reaction time, and reaction temperature of the enzyme (MTT); examples of the mineral or its salt and amount to be added; amount of water to be added; examples of starch food raw materials / starch foods; definition of staling of starch foods / inhibition thereof, etc. are the same as the definition, amount to be added, reaction time, and reaction temperature of the enzyme (MTT); examples of the mineral or its salt and amount to be added; amount of water to be added; examples of starch food raw materials / starch foods; definition of staling of starch foods / inhibition thereof, etc. in the method for producing starch foods of the present invention.

[0026] In one embodiment, the present invention (Invention 1) relates to an enzyme preparation containing maltotriosyltransferase and a mineral or a salt thereof selected from calcium and magnesium. In the enzyme preparation of the present invention, the definition, amount to be added, reaction time, and reaction temperature of the enzyme (MTT); examples and amounts of the mineral or a salt thereof; amount of water to be added; examples of starch food raw materials / starch foods; and definitions of starch food retrogradation / inhibition thereof are the same as the definition, amount to be added, reaction time, and reaction temperature of the enzyme (MTT); examples and amounts of the mineral or a salt thereof; amount of water to be added; examples of starch food raw materials / starch foods; and definitions of starch food retrogradation / inhibition thereof in the method for producing a starch food of the present invention. The enzyme preparation of the present invention can be used in the method for producing a starch food and the method for inhibiting starch food retrogradation of the present invention.

[0027] The second aspect of the present invention will now be described in detail. The method for producing a starch food of the present invention (second aspect) comprises adding to a starch food raw material: (1) maltotriosyltransferase and α-glucosidase, (2) a mineral selected from calcium and magnesium or a salt thereof, and (3) water, wherein the amount of the mineral or salt thereof added in (2) is such that when dissolved in the water in (3), the concentration in the solution becomes 0.15 mM to 75 mM.

[0028] In the second aspect of the present invention, two enzymes (maltotriosyltransferase and α-glucosidase) are used. The maltotriosyltransferase is as described in the first aspect of the present invention.

[0029] In the present invention (Invention 2), the amount of maltotriosyltransferase added per 1 g of starch food raw material is preferably 0.01 U or more, more preferably 0.02 U or more, even more preferably 0.05 U or more, and particularly preferably 0.1 U or more, 0.5 U or more, 1 U or more, 5 U or more, 10 U or more, 11 U or more, 12 U or more, 13 U or more, or 14 U or more. In the present invention (Invention 2), the amount of maltotriosyltransferase added per 1 g of starch food raw material is preferably 100 U or less, more preferably 75 U or less, even more preferably 50 U or less, 40 U or less, 30 U or less, 25 U or less, 20 U or less, 19 U or less, 18 U or less, 17 U or less, or 16 U or less in terms of enzyme activity. In the present invention (Invention 2), the amount of maltotriosyltransferase added is preferably 0.01 U or more, more preferably 0.02 U to 100 U, even more preferably 0.05 U to 75 U, and particularly preferably 0.1 U to 50 U, 1 U to 25 U, 10 U to 20 U, 11 U to 19 U, 12 U to 18 U, 13 U to 17 U, or 14 U to 16 U in terms of enzyme activity per 1 g of starch food raw material.

[0030] The reaction time of maltotriosyltransferase is not particularly limited as long as it is a time that allows the enzyme to act on the substrate substance, starch, but a practical reaction time is preferably 1 to 100 minutes, more preferably 10 to 50 minutes. The reaction temperature is also not particularly limited as long as it is within a range in which the enzyme maintains its activity, but a practical temperature range of 5 to 80°C is preferred. The enzymatic reaction can be terminated, for example, by heating at 90 to 100°C for 1 to 30 minutes.

[0031] α-Glucosidase (EC 3.2.1.20) is an enzyme that hydrolyzes non-reducing terminal α-1,4-glycosidic bonds to produce α-glucose. Examples of α-glucosidase include enzymes sold by Amano Enzyme Co., Ltd. under the trade names "Transglucosidase 'Amano'" and "α-Glucosidase 'Amano'." Regarding the enzymatic activity of α-glucosidase, 1 ml of 0.02 M acetate buffer (pH 5.0) was added to 1 ml of 1 mM α-methyl-D-glucoside, and 0.5 ml of enzyme solution was added. The reaction was allowed to proceed at 40°C for 60 minutes. One unit (U) of enzyme was defined as the amount of enzyme required to produce 1 μg of glucose in 2.5 ml of reaction solution.

[0032] In the present invention (Invention 2), the amount of α-glucosidase added is such that the enzymatic activity per 1 g of the starch food raw material is preferably 0.01 U or more, more preferably 0.02 U or more, even more preferably 0.05 U or more, and particularly preferably 0.1 U or more. In the present invention (Invention 2), the amount of α-glucosidase added is such that the enzymatic activity per 1 g of the starch food raw material is preferably 100 U or less, more preferably 50 U or less, and particularly preferably 10 U or less, 5 U or less, 3 U or less, 2 U or less, or 1 U or less. In the present invention (Invention 2), the amount of α-glucosidase added is preferably 0.01 U or more, more preferably 0.02 U to 100 U, even more preferably 0.05 U to 50 U, and particularly preferably 0.1 U to 10 U, 0.1 U to 5 U, 0.1 U to 3 U, 0.1 U to 2 U, or 0.1 U to 1 U in terms of enzyme activity per 1 g of starch food raw material.

[0033] The reaction time of α-glucosidase is not particularly limited as long as it is long enough for the enzyme to act on the starch substrate. A practical reaction time is preferably 1 to 100 minutes, more preferably 10 to 50 minutes. The reaction temperature is also not particularly limited as long as the enzyme maintains its activity. A practical temperature range is preferably 0 to 95°C (more preferably 5 to 90°C, even more preferably 10 to 85°C, and particularly preferably 20 to 80°C). The enzymatic reaction can be terminated, for example, by heating at 90 to 100°C for 1 to 30 minutes. In the production method of the present invention (Invention 2), two enzymes (maltotriosyltransferase and α-glucosidase) are preferably added simultaneously to act on the starch food material. When the two enzymes are added simultaneously, the reaction time and reaction temperature can be appropriately selected from the preferred ranges common to both enzymes.

[0034] The production method of the present invention (Invention 2) is characterized in that "(2) a mineral selected from calcium and magnesium or a salt thereof" is added to a starch food raw material together with two enzymes (maltotriosyltransferase and α-glucosidase). In the present invention, the calcium salt includes an inorganic salt of calcium or a salt of calcium with an organic acid, such as calcium chloride (CaCl ２ In the present invention, examples of magnesium salts include inorganic salts of magnesium and salts of magnesium with organic acids, such as magnesium chloride (MgCl ２ ) are listed.

[0035] In the production method of the present invention (Invention 2), the amount of (2) mineral or its salt added to the starch food raw material is such that, when dissolved in water (3), the concentration of (2) mineral or its salt in the solution is 0.15 mM or more, preferably 0.2 mM or more, 0.25 mM or more, 0.3 mM or more, more preferably 0.35 mM or more, even more preferably 0.4 mM or more, still more preferably 0.45 mM or more, particularly preferably 0.5 mM or more, 1 mM or more, or 5 mM or more. In the production method of the present invention (Invention 2), the amount of (2) mineral or its salt added to the starch food raw material is such that, when dissolved in water (3), the concentration of (2) mineral or its salt in the solution is 75 mM or less, preferably 70 mM or less, more preferably 65 mM or less, even more preferably 60 mM or less, still more preferably 55 mM or less, particularly preferably 50 mM or less, 25 mM or less, or 15 mM or less. In the production method of the present invention (Invention 2), the amount of (2) mineral or a salt thereof added to the starch food raw material is an amount such that, when dissolved in water (3), the concentration of (2) mineral or a salt thereof in the solution is preferably 0.2 mM to 70 mM, 0.25 mM to 70 mM, 0.3 mM to 70 mM, more preferably 0.35 mM to 65 mM, even more preferably 0.4 mM to 60 mM, still more preferably 0.45 mM to 55 mM, and particularly preferably 0.5 mM to 50 mM, 1 mM to 25 mM, or 5 mM to 15 mM.

[0036] In the production method of the present invention, the reaction time and temperature of the mineral or salt thereof (2) can be the same as the reaction time and temperature of the enzyme (maltotriosyltransferase or α-glucosidase) described above.

[0037] In the production method of the present invention, the amount of water (3) added varies depending on the type of starch food, but is generally, for example, 5 to 200 parts by weight, preferably 10 to 180 parts by weight, and more preferably 20 to 170 parts by weight, relative to 100 parts by weight of the starch food raw material. In the production method of the present invention, when the starch food raw material is raw rice (the starch food is cooked rice), the amount of water (3) added is, for example, 50 to 200 parts by weight, preferably 70 to 180 parts by weight, and more preferably 90 to 170 parts by weight, relative to 100 parts by weight of the raw rice.

[0038] In the present invention (Invention 2), the "starch food raw material" to which the above-mentioned enzymes (maltotriosyltransferase and α-glucosidase) and minerals are added refers to a food raw material containing starch. In the present invention, examples of the "starch food raw material" include raw rice and wheat flour.

[0039] In the manufacturing method of the present invention, the raw rice used as a raw material is not particularly limited in terms of rice variety or whether it has been polished or not, and examples include polished rice, brown rice, germinated brown rice, high-amylose rice, and low-amylose rice.

[0040] The manufacturing method of the present invention (Invention 2) will be specifically described below for the case where the starch food raw material is raw rice and the starch food is cooked rice. In the present invention, the rice cooking step preferably includes a step of raising the temperature from room temperature to 100°C over a period of preferably 5 to 60 minutes, more preferably 10 to 50 minutes, even more preferably 10 to 30 minutes, and even more preferably about 10 minutes, after adding the enzymes (maltotriosyltransferase and α-glucosidase) and minerals, taking into consideration the enzyme reaction time. When the temperature reaches 100°C, the enzymes are inactivated and the enzymatic reaction is terminated. This is then typically followed by a continuous boiling step (e.g., 15 to 30 minutes, preferably about 15 to 20 minutes) and a steaming step (e.g., 10 to 40 minutes, preferably about 10 to 20 minutes), to produce the modified cooked rice of the present invention (rice to which digestibility has been imparted). In the present invention, the rice cooking step is carried out for, for example, 3 hours or less, preferably 2 hours or less, and more preferably about 1 hour (about 50 to 60 minutes) after the addition of the enzymes (maltotriosyltransferase and α-glucosidase) and minerals. The present invention is advantageous in that the effects can be obtained even if the rice cooking step is completed within a short period of time (for example, about 1 hour) after the addition of the enzymes. In the present invention, the rice cooking step may be carried out using a commercially available rice cooker. The production method of the present invention may include steps other than the above steps (for example, a drying step, a freeze-drying step) as long as the effects of the present invention are not impaired.

[0041] The manufacturing method of the present invention (Invention 2) can produce modified starch foods (particularly starch foods to which digestibility has been imparted). In the present invention, "starch foods to which digestibility has been imparted" means starch foods that are less easily digestible than starch foods produced without the addition of the two enzymes and minerals of the present invention. The presence or absence of imparted digestibility can be evaluated by the artificial digestion test in Test Example 5 described below. Starch foods to which digestibility has been imparted, produced by the manufacturing method of the present invention (Invention 2), can be expected to suppress the rise in blood glucose levels after eating.

[0042] In the present invention (second invention), the definition and examples of "starch food" and the definition of "food" are the same as the definition and examples of "starch food" and the definition of "food" described above.

[0043] One aspect of the present invention (Invention 2) relates to a method for imparting digestibility to a starch food, which method of the present invention (Invention 2) for imparting digestibility to a starch food comprises adding to a starch food raw material: (1) maltotriosyltransferase and α-glucosidase, (2) a mineral selected from calcium and magnesium or a salt thereof, and (3) water, wherein the amount of the mineral or salt thereof added in (2) is such that when dissolved in the water in (3), the concentration in the solution becomes 0.15 mM to 75 mM. In the method of the present invention for imparting digestibility to starch foods, the definition, amount to be added, reaction time, and reaction temperature of the enzymes (MTT and α-glucosidase); examples of the minerals or salts thereof and amounts to be added; amount of water to be added; examples of starch food raw materials / starch foods; the definition of imparting digestibility, etc. are the same as the definition, amount to be added, reaction time, and reaction temperature of the enzymes (MTT and α-glucosidase); examples of the minerals or salts thereof and amounts to be added; amount of water to be added; examples of starch food raw materials / starch foods; the definition of imparting digestibility, etc. in the method of the present invention for producing starch foods.

[0044] In one embodiment, the present invention (Invention 2) relates to an enzyme preparation containing maltotriosyltransferase, α-glucosidase, and a mineral or a salt thereof selected from calcium and magnesium. In the enzyme preparation of the present invention, the definition, amount to be added, reaction time, and reaction temperature of the enzymes (MTT and α-glucosidase); examples and amounts to be added of the minerals or salts thereof; amount of water to be added; examples of starch food raw materials / starch foods; and the definition of imparting resistance to starch foods are the same as the definition, amount to be added, reaction time, and reaction temperature of the enzymes (MTT and α-glucosidase); examples and amounts to be added of the minerals or salts thereof; amount of water to be added; examples of starch food raw materials / starch foods; and the definition of imparting resistance to starch foods in the method for producing a starch food of the present invention. The enzyme preparation of the present invention can be used in the method for producing a starch food and the method for imparting resistance to a starch food of the present invention.

[0045] The present invention will be described in more detail below based on examples and test examples, but the present invention is not limited to these.

[0046] The enzymes used in the following Examples and Test Examples are as follows: Maltotriosyltransferase (MTT): Glycotransferase "Amano" (trade name), manufactured by Amano Enzyme Co., Ltd. α-Glucosidase (AG): α-Glucosidase "Amano" (trade name), manufactured by Amano Enzyme Co., Ltd.

[0047] Test Example 1: Effect of adding MTT and minerals on improving the quality of cooked rice foods (inhibition of deterioration during storage) The following test was conducted to confirm the effect of adding MTT and minerals on improving the quality of cooked rice foods (inhibition of deterioration during storage). (Production of cooked rice in Examples 1-1 to 1-2 and Comparative Examples 1-1 to 1-14) Raw materials were mixed according to the formulations shown in Tables 1-1 and 1-2, and cooked using a domestic rice cooker (IH rice cooker (product number JPF-G055), manufactured by Tiger Corporation) to produce the cooked rice of Examples 1-1 to 1-2 and Comparative Examples 1-1 to 1-14.

[0048]

[0049]

[0050] (Sensory Evaluation) 200 g of the cooked rice of Examples 1-1 to 1-2 and Comparative Examples 1-1 to 1-14 was packed into a storage container, sealed with a lid, and stored at 20°C for two days, after which a sensory evaluation was carried out. The sensory evaluation was carried out by three expert panelists, who evaluated the softness, stickiness, powdery texture, off-flavor, and overall evaluation (taste as cooked rice) according to the following evaluation criteria. The sensory evaluation scores were determined by consensus of the three panelists. The results are shown in Tables 1-3 and 1-4.

[0051] [Evaluation criteria (softness)] 5: Very soft, very preferable 4: Soft, preferable 3: Slightly softer than the sample containing only MTT 2: Hard, unfavorable (same as the sample containing only MTT) 1: Very hard, very unfavorable (same as the control)

[0052] [Evaluation criteria (stickiness)] 5: Very sticky, very preferable 4: Sticky, preferable 3: Slightly stickier than the sample with only MTT added 2: Not very sticky, not preferable (same as the sample with only MTT added) 1: Almost no stickiness, very unpreferable (same as the control)

[0053] [Evaluation criteria (powderyness)] 5: Not powdery at all, very preferable 4: Almost no powdery feeling, preferable 3: Less powdery than the sample containing only MTT 2: Powdery, unfavorable (same as the sample containing only MTT) 1: Very powdery, very unfavorable (same as the control)

[0054] [Evaluation criteria (off-flavor)] 3: Off-flavor is slightly present (same as the control and the sample containing only MTT) 2: Off-flavor is present and undesirable 1: Off-flavor is very present and undesirable

[0055] [Evaluation criteria (overall evaluation: deliciousness as cooked rice)] 5: Very delicious, very preferable 4: Delicious, preferable 3: Slightly more delicious than the control (same as the sample with only MTT added) 2: Not tasty, not preferable (same as the control) 1: Very unpalatable, very unpreferable

[0056]

[0057]

[0058] From the results in Tables 1-3 and 1-4, it can be seen that MTT was used and that a mineral (CaCl) was added in an amount that would give a concentration of 5.0 mM in the solution when dissolved in the water used. ２ or MgCl ２ ) were superior to the cooked rice of Comparative Example 1-1 (control) produced without MTT and minerals, and the cooked rice of Comparative Example 1-2 produced with MTT but without minerals in terms of softness, stickiness, powdery texture, and overall taste (taste) after storage at 20°C for 2 days. ２ or MgCl ２ The cooked rice of Examples 1-1 and 1-2 produced by adding MTT and minerals was stored at 20°C for 2 days, and the sensory evaluation of off-flavor after storage at 20°C was equivalent (3 points) to the cooked rice of Comparative Example 1-1 (control) produced without using MTT and minerals.

[0059] Test Example 2: Effect of adding enzymes and minerals on improving the quality of cooked rice foods (inhibition of deterioration during storage) The following test was conducted to confirm the effect of adding enzymes and minerals on improving the quality of cooked rice foods (inhibition of deterioration during storage). (Production of cooked rice in Examples 2-1 to 2-6 and Comparative Examples 2-1 to 2-6) Raw materials were mixed according to the formulations shown in Tables 2-1 and 2-2, and cooked using a domestic rice cooker (IH rice cooker (product number JPF-G055), manufactured by Tiger Corporation) to produce the cooked rice of Examples 2-1 to 2-6 and Comparative Examples 2-1 to 2-6.

[0060]

[0061]

[0062] (Sensory Evaluation) 200 g of the cooked rice of Examples 2-1 to 2-6 and Comparative Examples 2-1 to 2-6 was packed into a storage container, sealed with a lid, and stored at 20°C for two days, after which a sensory evaluation was performed. The sensory evaluation was performed by three expert panelists, who evaluated the softness, stickiness, powdery texture, off-flavor, and overall evaluation (taste as cooked rice) according to the same evaluation criteria as in Test Example 1. The sensory evaluation scores were determined by consensus of the three panelists. The results are shown in Tables 2-3 and 2-4.

[0063] (Measurement using a texture analyzer (sometimes referred to as "TA" in this specification)) In order to confirm the hardness and stickiness of the cooked rice of Examples 2-1 to 2-6 and Comparative Examples 2-1 to 2-6, TA measurements were carried out using the following method. Physical properties were evaluated using a texture analyzer (manufactured by Stable Micro Systems). One grain of cooked rice that had undergone the storage test was compressed to 90% at 1 mm / s with a 3 cm diameter acrylic cylindrical plunger, and the breaking stress at 90% compression was taken as hardness, and the negative peak stress at 90% compression was taken as stickiness. The results are shown in Tables 2-3 and 2-4.

[0064]

[0065]

[0066] From the results in Tables 2-3 and 2-4, it was found that MTT was used and that minerals (CaCl) were added in an amount that would result in a solution concentration of 0.5 to 50.0 mM when dissolved in the water used. ２ or MgCl ２ ) were superior to the cooked rice of Comparative Example 2-1 (control) produced without MTT and minerals and the cooked rice of Comparative Example 2-2 produced with MTT but without minerals in terms of softness, stickiness, powdery texture, and overall taste after storage at 20°C for 2 days. ２ or MgCl ２The cooked rice of Examples 2-1 to 2-6 produced by adding MTT and minerals was stored at 20°C for 2 days, and the sensory evaluation of off-flavor after storage at 20°C was equivalent (3 points) to the cooked rice of Comparative Example 1-1 (control) produced without using MTT and minerals.

[0067] Test Example 3: Effect of Adding Enzymes and Minerals on Bread Modification (Inhibition of Deterioration During Storage) The following test was conducted to confirm the effect of adding enzymes and minerals on bread modification (inhibition of deterioration during storage). (Production of Bread of Examples 3-1 to 3-2 and Comparative Examples 3-1 to 3-4) The ingredients according to the formulations shown in Table 3-1 were placed in a home automatic bread maker (Home Bakery (product number PY-D532), manufactured by Twinbird Corporation), and bread was automatically made in the "white bread mode, normal browning" mode. After baking, the bread was removed from the bread maker and allowed to cool for 1.5 hours to produce the bread of Examples 3-1 to 3-2 and Comparative Examples 3-1 to 3-4.

[0068]

[0069] (Sensory Evaluation) The breads of Examples 3-1 to 3-2 and Comparative Examples 3-1 to 3-4 were each cut and removed by 1.5 cm from both the left and right ends of the bread, and then sliced ​​vertically into 2 cm thick pieces. Each slice of bread was placed in a polyethylene bag with a zipper, the zipper was closed to seal, and the bread was stored at 10°C for two days, after which a sensory evaluation was performed. The sensory evaluation was performed by three expert panelists, who evaluated the softness, moistness, and overall evaluation (taste as bread) according to the following evaluation criteria. The sensory evaluation scores were determined by consensus of the three panelists. The results are shown in Table 3-2.

[0070] [Evaluation criteria (bread softness)] 5: Very soft, very preferable 4: Soft, preferable 3: Slightly softer than the sample with only MTT added 2: Hard, unfavorable (same as the sample with only MTT added) 1: Very hard, very unfavorable (same as the control)

[0071] [Evaluation criteria (bread moistness: degree of moisture content)] 5: Very moist, very preferable 4: Moist, preferable 3: Slightly moister than the sample with only MTT added 2: Not very moist, not preferable (same as the sample with only MTT added) 1: Almost no moistness, very unpreferable (same as the control)

[0072] [Evaluation criteria (overall evaluation: taste as bread)] 5: Very tasty, very preferable 4: Tasty, preferable 3: Slightly tastier than the sample with only MTT added 2: Not tasty, not preferable (same as the sample with only MTT added) 1: Very tasty, very unfavorable (same as the control)

[0073]

[0074] From the results in Table 3-2, MTT was used, and a mineral (CaCl) was added in an amount that would result in a solution concentration of 10.0 mM when dissolved in the water used. ２ or MgCl ２ It was confirmed that the breads of Examples 3-1 and 3-2 produced by adding MTT and minerals were superior in sensory evaluation of bread softness, moistness, and overall taste (taste) after storage at 10°C for 2 days compared to the bread of Comparative Example 3-1 (control) produced without MTT and minerals, and the bread of Comparative Example 3-2 produced with MTT but without minerals.

[0075] Test Example 4: Effect of Adding Enzymes and Minerals on Pasta Modification (Inhibition of Deterioration During Storage) The following test was conducted to confirm the effect of adding enzymes and minerals on pasta modification (inhibition of deterioration during storage). (Production of Pasta in Examples 4-1 to 4-2 and Comparative Examples 4-1 to 4-4) Raw materials with the formulations shown in Table 4-1 were placed in an automatic home noodle maker (Noodle Maker (product number HR2369 / 01), manufactured by Philips) and automatically produced into fresh pasta. The fresh pasta obtained was allowed to stand at room temperature for 15 minutes and then boiled in boiling water for 5 minutes. The boiled pasta was drained and allowed to cool, and the pasta of Examples 4-1 to 4-2 and Comparative Examples 4-1 to 4-4 was produced.

[0076]

[0077] (Sensory Evaluation) The pastas of Examples 4-1 and 4-2 and Comparative Examples 4-1 to 4-4 were packed into storage containers, sealed with lids, and stored at 10°C for two days, after which a sensory evaluation was carried out. The sensory evaluation was carried out by three expert panelists, who evaluated the softness, stickiness, powdery texture, and overall evaluation (taste as pasta) according to the following evaluation criteria. The sensory evaluation scores were determined by consensus of the three panelists. The results are shown in Table 4-2.

[0078] [Evaluation criteria (pasta softness)] 5: Very soft, very preferable 4: Soft, preferable 3: Slightly softer than the sample with only MTT added 2: Hard, unfavorable (same as the sample with only MTT added) 1: Very hard, very unfavorable (same as the control)

[0079] [Evaluation criteria (stickiness: degree of stretching)] 5: Very sticky, very preferable 4: Sticky, preferable 3: Slightly stickier than the sample with only MTT added 2: Not very sticky, not preferable (same as the sample with only MTT added) 1: Almost no stickiness, very unpreferable (same as the control)

[0080] [Evaluation criteria (powderyness: degree to which powder feels attached)] 5: Not powdery at all, very preferable 4: Almost no powdery feeling, preferable 3: Less powdery than the sample containing only MTT 2: Powdery, unfavorable (same as the sample containing only MTT) 1: Very powdery, very unfavorable (same as the control)

[0081] [Evaluation criteria (overall evaluation: deliciousness as pasta)] 5: Very delicious, very preferable 4: Delicious, preferable 3: Slightly more delicious than the sample with only MTT added 2: Not tasty, not preferable (same as the sample with only MTT added) 1: Very untasty, very unpreferable (same as the control)

[0082]

[0083] From the results in Table 4-2, it can be seen that MTT was used and that the mineral (CaCl) was added in an amount that would give a concentration of 10.0 mM when dissolved in the water used. ２ or MgCl ２ It was confirmed that the pasta of Examples 4-1 and 4-2, which were produced by adding MTT and minerals, were superior in sensory evaluation of pasta softness, stickiness, powdery texture, and overall evaluation (taste as pasta) after storage at 10°C for 2 days, compared to the pasta of Comparative Example 4-1 (control) which was produced without using MTT and minerals, and the pasta of Comparative Example 4-2 which was produced with MTT but without minerals.

[0084] Test Example 5: Effect of adding enzymes (MTT and α-glucosidase (AG)) and minerals on improving cooked rice foods (imparting digestibility to cooked rice) The following artificial digestion test was conducted to confirm the effect of adding two enzymes (MTT and AG) and minerals on improving cooked rice foods (imparting digestibility to cooked rice). (Production of cooked rice in Example 5-1 and Comparative Examples 5-1 to 5-2) Raw materials were mixed according to the formulations shown in Table 5-1 and cooked using a domestic rice cooker (IH rice cooker (product number JPF-G055), manufactured by Tiger Corporation) to produce the cooked rice of Example 5-1 and Comparative Examples 5-1 to 5-2.

[0085]

[0086] (Artificial Digestion Test) 10 g of cooked rice (sample) from Example 5-1 and Comparative Examples 5-1 and 5-2 was placed in a 50 mL Eppendorf tube, followed by the addition of 40 g of water. The sample placed in the tube was placed in a 40 °C incubator with a rotator at 60 rpm, and the temperature was adjusted. After adjusting the temperature, digestive enzymes (0.31 g of amiloglucosidase (Sigma) and 0.076 g of pancreatine (Wako)) were added, and the mixture was allowed to react for 60 minutes in a 40 °C incubator with a rotator at 60 rpm. After the reaction, the mixture was heated to 100 °C for 5 minutes to terminate the enzyme reaction, and a reaction solution was obtained. The amount of free glucose in the resulting reaction solution was determined by the glucose oxidase method using a glucose measurement kit (Labo Assay TM Glucose (trade name), Fujifilm Wako Pure Chemical Industries, Ltd.). The inhibition rate of digestive enzyme degradation for each sample of Comparative Example 5-2 and Example 5-1 relative to the control (Comparative Example 5-1) was calculated using the following formula. The results are shown in Table 5-2.

[0087]

[0088]

[0089] The results in Table 5-2 confirm that the cooked rice of Example 5-1, which was produced using MTT and AG and adding a mineral (calcium lactate) in an amount such that the concentration in the solution when dissolved in the water used was 10.0 mM, had a higher inhibition rate of decomposition by digestive enzymes (i.e., was highly indigestible) than the cooked rice of Comparative Example 5-2, which was produced using MTT and AG but without adding any minerals.

[0090] According to the present invention, it is possible to provide a modified starch food (particularly a starch food in which retrogradation is inhibited, or a starch food that has been imparted with resistance to digestion and can inhibit an increase in blood glucose level after eating).

[0091] This application is based on patent application No. 2024-105760 filed in Japan, the contents of which are incorporated in their entirety herein.

Claims

1. A method for producing a starch food, comprising adding (1) maltotriosyltransferase, (2) a mineral selected from calcium and magnesium or a salt thereof, and (3) water to a starch food raw material, wherein the amount of the mineral or salt thereof added in (2) is such that when dissolved in the water in (3), the concentration in the solution becomes 0.15 mM to 75 mM.

2. The method according to claim 1, wherein the starch food raw material is raw rice and the starch food is cooked rice.

3. A method for inhibiting aging of starch foods, comprising adding to a starch food raw material: (1) maltotriosyltransferase; (2) a mineral selected from calcium and magnesium or a salt thereof; and (3) water, wherein the amount of the mineral or salt thereof added in (2) is such that when dissolved in the water in (3), the concentration in the solution becomes 0.15 mM to 75 mM.

4. The method for inhibiting aging according to claim 3, wherein the starch food raw material is raw rice and the starch food is cooked rice.

5. An enzyme preparation containing maltotriosyltransferase and a mineral selected from calcium and magnesium or a salt thereof.

6. The enzyme preparation according to claim 5, which is added to starch food raw materials to inhibit retrogradation of the starch food.

7. The enzyme preparation according to claim 6, wherein the starch food raw material is raw rice and the starch food is cooked rice.

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