Method for modifying gel stress of thermally denatured gel of vegetable protein

Abstract

The purpose of the present invention is to provide a technique for changing a gel stress that a thermally denatured gel of a vegetable protein inherently has. A modified vegetable protein having a deamidated side chain according to the present invention can be modified with respect to the gel stress of a thermally modified gel thereof which is obtained by thermally modifying and gelling the modified vegetable protein in the presence of water and in the absence of a coagulant.

Description

Method for modifying gel stress of heat-denatured gel of plant protein

[0001] The present invention relates to a method for modifying gel stress of a heat-denatured gel of plant protein.

[0002] Except for liquid beverages with extremely low viscosity or solid foods that do not contain water, many foods are in a gel state. In food science, the role played by gel physical properties is extremely important (Non-Patent Document 1). The degree of gel ranges widely from those close to liquids to those close to solids, and this wide range of gel properties gives diversity to foods.

[0003] In recent years, in the food market, as the share of foods using plant protein as an alternative to animal protein foods has been increasing, research on the properties of plant protein has been actively conducted.

[0004] For example, in Patent Document 1, it is disclosed that a protein-deamidated soybean protein-containing composition can improve the hardness and the like of a heat-coagulated gel of egg white protein.

[0005] Journal of the Japanese Society for Food Science and Technology, Vol. 44, No. 9, 681 - 688 (1997)

[0006] International Publication No. 2022 / 114059

[0007] Foods using plant protein used to target some consumers such as vegetarians or vegans. However, in recent years, the demand trend has changed, and due to the increasing awareness of health orientation, diet, environmental issues, animal protection, etc., they have come to be noticed by a wide range of consumers. Plant protein can generally induce gel formation by heat treatment, but the texture may be too soft or too hard depending on the product concept of the food. In order to further expand the possibility of creating plant protein-containing foods according to the product concept, a technology for changing the gel stress inherent in the heat-denatured gel of plant protein is desired.

[0008] Therefore, an object of the present invention is to provide a technology for changing the gel stress inherent in a heat-denatured gel of plant protein.

[0009] As a result of diligent research, the inventors have found that the gel stress of a heat-denatured gel of deamidated plant protein differs from the gel stress inherent in a heat-denatured gel of undeamidated plant protein. This invention was completed by further research based on this finding. That is, this invention provides the invention in the following embodiments.

[0010] Item 1. A method for modifying the gel stress of a thermally denatured gel of a plant protein, comprising a thermal denaturation gelation step of thermally denaturing a modified plant protein having deamidated side chains in the presence of water and in the absence of a coagulant. Item 2. The method according to item 1, wherein the thermal denaturation gelation step is carried out under any of the following conditions (I) to (V), and the gel stress modification is an increase in gel stress: (I) the plant protein is pea protein and the pH condition is 4.8 to 5.2 or 6.3 to 8.2, (II) the plant protein is soy protein and the pH condition is 3.8 to 5.2 or 6.3 to 8.2, (III) the plant protein is lupin bean protein and / or broad bean protein and the pH condition is 4.8 to 5.2, (IV) the plant protein is mung bean protein and / or lentil protein and the pH condition is 4.8 to 5.7, and (V) the plant protein is chickpea protein and the pH condition is 5.3 to 8.2. Item 3. The method according to item 1, wherein the thermal denaturation gelation step is carried out under any of the following conditions (i) to (iv), and the gel stress modification is gel stress reduction: (i) the plant protein is pea protein and the pH condition is 3.8 to 4.2 or 5.3 to 6.2, (ii) the plant protein is soy protein and the pH condition is 5.3 to 6.2, (iii) the plant protein is lupin bean protein and / or broad bean protein and the pH condition is 3.8 to 4.2 or 5.3 to 8.2, and (iv) the plant protein is mung bean protein and / or lentil protein and the pH condition is 3.8 to 4.2 or 5.8 to 8.2. Item 4. The method according to any of items 1 to 3, wherein the modified plant protein is a product of plant protein treated with protein glutaminase. Item 5. A method for producing a thermally denatured gel of a modified plant protein, comprising a thermal denaturation gelation step of thermally denaturing and gelling a modified plant protein having deamidated side chains in the presence of water and in the absence of a coagulant. Item 6. The method according to Item 5, wherein the modified plant protein is a product of processing a plant protein with protein glutaminase. Item 7. A gelling agent for thermally denaturing and gelling in the presence of water and in the absence of a coagulant, comprising a modified plant protein having deamidated side chains.Item 8. The gelling agent according to Item 7, wherein the side chain is a glutamine residue side chain amide group. Item 9. A gel stress modifier for a plant protein coagulant-free, heat-denatured hydrogel, comprising a protein deamidation enzyme. Item 10. A food or beverage comprising a modified plant protein coagulant-free, heat-denatured hydrogel having a deamidated side chain.

[0011] The present invention provides a technique for altering the gel stress inherent in a heat-denatured gel of plant protein.

[0012] 1. Method for modifying the gel stress of a thermally denatured gel of a plant protein The present invention provides a method for modifying the gel stress of a thermally denatured gel of a plant protein, characterized by comprising a thermal denaturation gelation step in which a modified plant protein having deamidated side chains is thermally denatured and gelled in the presence of water and in the absence of a coagulant. The present invention provides a method for modifying the gel stress of a thermally denatured gel of a plant protein, which may further include an enzyme treatment step prior to the thermal denaturation gelation step, in which the plant protein is treated with a protein deamidation enzyme to obtain the modified plant protein having deamidated side chains.

[0013] 1-1. Enzyme Treatment Process In the enzyme treatment process, a modified plant protein is obtained by treating the plant protein with a protein deamidation enzyme to deamidate the amide group in the side chain, thereby obtaining a modified plant protein with a deamidated side chain. Specifically, this process can be carried out by preparing a plant protein mixture containing the plant protein material and the protein deamidation enzyme in water, and subjecting it to conditions that allow the enzymatic reaction to proceed.

[0014] 1-1-1. Plant-based proteins There are no particular restrictions on plant-based proteins, as long as their origin is plant-based. Examples include cereals such as peas, soybeans, lupin beans, mung beans, lentils, broad beans, chickpeas, black beans, and kidney beans; grains such as wheat, barley, oats, sorghum, rice, rye, buckwheat, millet, foxtail millet, teff, quinoa, corn, and potatoes; nuts and seeds such as almonds, coconuts, peanuts, cashews, hazelnuts, pecans, macadamia nuts, pistachios, walnuts, Brazil nuts, pili nuts, chestnuts, sesame seeds, pine nuts, hemp seeds (industrial hemp), chia seeds, kia, amaranth, canary seeds, and flaxseed; and natural proteins contained in algae, etc.

[0015] These plant proteins may be used individually or in combination of two or more proteins of different origins.

[0016] Among these plant proteins, legume proteins are preferred, more preferably legume proteins selected from peas, soybeans, lupin beans, mung beans, lentils, broad beans, chickpeas, black beans, and kidney beans, and even more preferably legume proteins selected from peas, soybeans, lupin beans, mung beans, lentils, broad beans, and chickpeas.

[0017] The plant-based protein material is not particularly limited as long as it contains plant protein, and examples include crushed material of the plant itself; plant-based milk substitute (also called plant-based milk); plant-based protein material obtained by removing at least some of the components other than protein from the plant, thereby purifying the plant protein to any degree; and suspensions obtained by suspending these in water.

[0018] The plant protein content in the plant protein material is not particularly limited, but examples include 0.01 to 95% by weight, 0.05 to 95% by weight, 0.1 to 95% by weight, 1 to 95% by weight, or 5 to 95% by weight, preferably 10 to 95% by weight, 20 to 95% by weight, 30 to 95% by weight, or 40 to 95% by weight, more preferably 50 to 95% by weight, 60 to 95% by weight, 70 to 95% by weight, 80 to 95% by weight, 80 to 90% by weight, or 80 to 87% by weight, relative to the dry weight of the plant protein material.

[0019] The plant protein content in the plant protein mixture is not particularly limited, but examples include 0.001 to 50% by weight, 0.01 to 40% by weight, 0.1 to 30% by weight, or 0.5 to 25% by weight, preferably 0.9 to 20% by weight, or 1 to 15% by weight, more preferably 1.5 to 10% by weight, or 2 to 8% by weight, and even more preferably 2.5 to 6% by weight, 3 to 5.5% by weight, or 4 to 5% by weight.

[0020] 1-1-2. Protein deamidases Protein deamidases are enzymes that degrade the amide group-containing side chains of proteins without cleaving peptide bonds or crosslinking proteins, and their type and origin are not particularly limited.

[0021] Examples of protein deamidation enzymes include enzymes that deamidate glutamine residues in proteins and convert them to glutamic acid (e.g., protein glutaminase), and enzymes that deamidate asparagine residues in proteins and convert them to aspartic acid (e.g., protein asparaginase).

[0022] More specific examples of protein deamide enzymes include those derived from the genera Chryseobacterium, Flavobacterium, Empedobacter, Sphingobacterium, Aureobacterium, Myroides, Luteimicrobium, Agromyces, Microbacterium, or Leifsonia. These protein deamide enzymes are well known; see, for example, JP2000-50887A, JP2001-218590A, WO2006 / 075772A1, WO2015 / 133590, etc. These protein deamide enzymes may be used individually or in combination.

[0023] Among these protein deamide enzymes, preferably are protein deamide enzymes derived from the genus Chryseobacterium, more preferably protein glutaminases derived from the genus Chryseobacterium, even more preferably protein glutaminases derived from the species Chryseobacterium proteolyticum, and even more preferably protein glutaminases derived from Chryseobacterium proteolyticum strain 9670.

[0024] Protein deamide enzymes can be prepared from the culture medium of the microorganism from which the above-mentioned protein deamide enzymes originate. Specific preparation methods include recovering the protein deamide enzyme from the culture medium or cells of the above-mentioned microorganisms. For example, when using a protein deamide enzyme-secreting microorganism, the cells can be recovered from the culture medium by filtration, centrifugation, etc., as needed, and then the enzyme can be separated and / or purified. When using a protein deamide enzyme-non-secreting microorganism, the cells can be recovered from the culture medium by filtration, centrifugation, etc., as needed, and then the cells can be crushed by pressurization, sonication, etc., to expose the enzyme, and then the enzyme can be separated and / or purified. The enzyme separation and / or purification method can be any known protein separation and / or purification method without particular limitation, such as centrifugation, UF concentration, salting out, and various chromatography methods using ion exchange resins. The separated and / or purified enzyme can be powdered by drying methods such as freeze-drying or vacuum drying, and can also be powdered using appropriate excipients and / or drying aids in the drying method. Furthermore, the separated and / or purified enzymes can be liquefied by adding appropriate additives and sterilizing by filtration.

[0025] The amount of protein deamidation enzyme used is not particularly limited, but examples of the amount used per gram of plant protein include 0.01 to 100 U, 0.05 to 50 U, 0.1 to 20 U, or 0.5 to 18 U, preferably 1 to 16 U, or 3 to 14 U, more preferably 4 to 12 U, 5 to 10 U, or 5.5 to 8 U.

[0026] Regarding the activity of protein deamidase enzymes, one unit (1 U) is defined as the amount of enzyme that releases 1 μmol of ammonia per minute using benzyloxycarbonyl-L-glutaminilglycine (Z-Gln-Gly) as the substrate.

[0027] 1-1-3. Reaction Conditions The temperature conditions for the treatment with the protein deamidation enzyme are not particularly limited and can be appropriately determined by those skilled in the art depending on the optimal temperature of the enzyme used and / or the thermal properties of the plant protein material, but examples include 20 to 70°C, preferably 30 to 65°C, more preferably 40 to 60°C, and even more preferably 45 to 55°C.

[0028] The pH conditions for treatment with protein deamidation enzymes are not particularly limited and can be appropriately determined by those skilled in the art depending on the optimal pH of the enzyme used and / or the pH characteristics of the plant protein material. For example, a pH of 6 to 8, preferably 6.5 to 7.5, at 25°C is used.

[0029] The time conditions for treatment with the protein deamidation enzyme are not particularly limited and can be appropriately determined by those skilled in the art depending on the reaction scale, etc., but for example, 0.5 to 24 hours, preferably 6 to 20 hours, and more preferably 12 to 18 hours are given.

[0030] 1-1-4. After enzyme treatment of modified plant proteins with deamidated side chains, the plant protein mixture can be cooled after enzyme deactivation treatment as needed. This yields modified plant proteins with deamidated side chains. When protein glutaminase is used as the protein deamidation enzyme, the amide group of the glutamine residue in the side chain of the modified plant protein with deamidated side chains is deamidated. When protein asparaginase is used as the protein deamidation enzyme, the amide group of the asparagine residue in the side chain of the modified plant protein with deamidated side chains is deamidated.

[0031] The modified plant protein having deamidated side chains may be in a form coexisting with water (aqueous solution, suspension, etc.) or in a form from which water has been removed (freeze-dried block, powder, etc.).

[0032] 1-2. Thermal Denaturation Gelation Process In the thermal denaturation gelation process, the modified plant protein having deamidated side chains is thermally denatured and gelled in the presence of water and in the absence of a coagulant. Specifically, thermal denaturation can be achieved by subjecting a mixture containing the modified plant protein having deamidated side chains and a pH adjusting agent (added as needed) in water to thermal denaturation gelation conditions.

[0033] 1-2-1. Concentration of Modified Plant Protein The concentration of modified plant protein having deamidated side chains contained in the mixed solution is not particularly limited, but examples include 1 to 60% by weight, 2.5 to 50% by weight, or 5 to 40% by weight, preferably 10 to 30% by weight, and more preferably 15 to 25% by weight.

[0034] The mixture does not contain a coagulant. The coagulant is not particularly limited as long as it crosslinks plant proteins, but examples include water-soluble calcium salts (calcium chloride, calcium sulfate, etc.) and water-soluble magnesium salts (magnesium chloride, etc.).

[0035] 1-2-2. pH Conditions The pH conditions for thermal denaturation gelation (the pH shall be the pH at 25°C; the same applies hereinafter) are not particularly limited and should be determined according to the purpose of modifying the gel stress of the thermal denatured gel (specifically, whether the purpose is to increase or decrease the gel stress of a thermal denatured gel of a modified plant protein with deamidated side chains compared to the gel stress of a thermal denatured gel of an unmodified plant protein) and the type of plant protein.

[0036] When the purpose of modifying gel stress is to increase gel stress, and the plant protein is derived from peas, soybeans, lupin beans, mung beans, lentils, broad beans, or chickpeas, the pH conditions for thermal denaturation gelation can be any of the following conditions (I) to (V).

[0037] (I) The plant protein is pea protein, and the pH conditions are 4.8 to 5.2 (or any of 4.9 to 5.1 or 4.9 to 5.0), or 6.3 to 8.2 (or any of 6.4 to 8.2, 6.8 to 8.2, 6.9 to 8.2, 7.2 to 8.2, 7.1 to 8.2, or 7.8 to 8.2); preferably 6.3 to 8.2 or 6.4 to 8.2; more preferably 6.8 to 8.2, 6.9 to 8.2, 7.2 to 8.2, or 7.1 to 8.2; even more preferably 7.8 to 8.2.

[0038] (II) The plant protein is soy protein, and the pH is 3.8 to 5.2 (or any of 3.9 to 5.2, 4.8 to 5.2, or 4.9 to 5.1), or 6.3 to 8.2 (or any of 6.8 to 8.2, 6.8 to 7.2, or 6.9 to 7.1); preferably 4.8 to 5.2 (or 4.9 to 5.1), or 6.8 to 8.2 (or any of 6.9 to 8.1, 6.9 to 7.2, or 6.9 to 7.1); more preferably 6.8 to 8.2 (or any of 6.9 to 8.1, 6.9 to 7.2, or 6.9 to 7.1); even more preferably 6.9 to 8.1 (or any of 6.9 to 7.2 or 6.9 to 7.1); even more preferably 6.9 to 7.2 (or 6.9 to 7.1).

[0039] (III) The plant protein is lupin bean protein and / or broad bean protein; preferably lupin bean protein, and the pH condition is 4.8 to 5.2 (or 4.9 to 5.1).

[0040] (IV) The plant protein is mung bean protein and / or lentil protein; more preferably mung bean protein, and the pH condition is 4.8 to 5.7 (or any of 4.8 to 5.6, 4.8 to 5.2, or 4.8 to 5.1); preferably 4.8 to 5.2 (or 4.8 to 5.1).

[0041] (V) The plant protein is chickpea protein, and the pH is 5.3 to 8.2 (or any of 5.4 to 8.2, 5.4 to 7.5, 5.4 to 7, 5.4 to 6.2, 5.4 to 6.1, or 5.9 to 6.1); preferably 5.4 to 6.2 (or any of 5.4 to 6.1 or 5.9 to 6.1).

[0042] When the purpose of modifying the gel stress is to weaken the gel stress, and the plant protein is the protein of pea, soybean, lupin bean, broad bean, lentil bean, or cowpea, the pH conditions for heat denaturation gelation include any of the following conditions (i) to (iv).

[0043] (i) - When the plant protein is pea protein, and - the pH condition is 3.8 to 4.2 (or 3.9 to 4.1), or 5.3 to 6.2 (or any of 5.4 to 6.2, 5.8 to 6.2, 5.9 to 6.2, 5.9 to 6.1); preferably 5.3 to 6.2 (or any of 5.4 to 6.2, 5.8 to 6.2, 5.9 to 6.2, 5.9 to 6.1); more preferably 5.4 to 6.2 (or any of 5.8 to 6.2, 5.9 to 6.2, 5.9 to 6.1); still more preferably 5.8 to 6.2 (or any of 5.9 to 6.2, 5.9 to 6.1); even more preferably 5.9 to 6.2 (or 5.9 to 6.1).

[0044] (ii) - When the plant protein is soybean protein, and - the pH condition is 5.3 to 6.2 (or any of 5.4 to 6.2, 5.8 to 6.2, 5.9 to 6.2, 5.9 to 6.1); preferably 5.8 to 6.2 (or any of 5.9 to 6.2, 5.9 to 6.1); more preferably 5.9 to 6.2 (or 5.9 to 6.1).

[0045] (iii) - When the plant protein is lupin bean protein and / or cowpea protein; preferably lupin bean protein, and - the pH condition is 3.8 to 4.2 (or 3.9 to 4.1), or 5.3 to 8.2 (or 5.4 to 8.1); in the case of lupin bean protein, preferably 3.8 to 4.2 (or 3.9 to 4.1), or 5.8 to 6.2 (or 5.9 to 6.2); more preferably 5.8 to 6.2 (or 5.9 to 6.2); in the case of cowpea protein, preferably 5.8 to 7.2 (or 5.9 to 7.1); more preferably 5.8 to 6.2 (or 5.9 to 6.1).

[0046] (iv) - The plant protein is licorice protein and / or lentil bean protein, and - The pH condition is 3.8 to 4.2 (or 3.9 to 4.1), or 5.8 to 8.2 (or 5.9 to 8.2); In the case of licorice protein, preferably 5.8 to 6.2 (or 5.9 to 6.1); In the case of lentil bean protein, preferably 3.8 to 4.2 (or 3.9 to 4.1), or 6.8 to 8.2 (or 6.9 to 8.2); more preferably 6.8 to 8.2 (or 6.9 to 8.2); even more preferably 7.8 to 8.2 (or 7.9 to 8.2).

[0047] 1-2-3. For the temperature conditions of other conditions of heat denaturation gelation, it is not particularly limited as long as it is a temperature at which gelation is possible. Specific temperatures include, for example, 70 to 120 °C, or 80 to 115 °C, preferably 90 to 110 °C, more preferably 95 to 105 °C.

[0048] The time conditions for heat denaturation gelation may be appropriately determined according to the charging scale, temperature conditions, etc., and examples include 5 to 30 minutes, preferably 10 to 20 minutes.

[0049] 1-3. By heat denaturation gelation of a modified plant protein having a deamidated side chain, a coagulant-free heat denatured hydrogel of the modified plant protein (hereinafter, also simply referred to as "heat denatured gel of the modified plant protein" or "heat denatured gel") can be obtained. The heat denatured gel of the modified plant protein has a modified gel stress as compared with the coagulant-free heat denatured hydrogel of the unmodified plant protein. As a specific mode of modification, in the case of a heat denatured gel obtained under the conditions of "1-2-2. pH condition" where the purpose of modifying the gel stress is an increase in the gel stress, the gel stress increases, and in the case of a heat denatured gel obtained under the conditions of "the purpose of modifying the gel stress is a decrease in the gel stress", the gel stress decreases.

[0050] 2. Method for producing a thermally denatured gel of modified plant protein The method for producing a thermally denatured gel of modified plant protein of the present invention is characterized by comprising a thermal denaturation gelation step in which a modified plant protein having deamidated side chains is thermally denatured and gelled in the presence of water and in the absence of a coagulant. The method for producing a thermally denatured gel of modified plant protein of the present invention may further include an enzymatic treatment step prior to the thermal denaturation gelation step, in which the plant protein is treated with a protein deamidation enzyme to obtain the modified plant protein having deamidated side chains.

[0051] Details of the enzyme treatment process are as described in "1-1. Enzyme Treatment Process" above, details of the thermal denaturation gelation process are as described in "1-2. Thermal Denaturation Gelation Process" above, and thermal denaturation gels of modified plant proteins are as described in "1-3. Thermal Denaturation Gels" above.

[0052] 3. Gelling Agent The gelling agent of the present invention is characterized by comprising a modified plant protein having a deamidated side chain, and being used for thermal denaturation gelation in the presence of water and in the absence of a coagulant.

[0053] The modified plant protein having deamidated side chains, which is the active ingredient of the gelling agent of the present invention, is as described in "1-1-4. Modified plant protein having deamidated side chains". Furthermore, the method for producing the modified plant protein having deamidated side chains is as described in "1-1. Enzyme treatment step" above.

[0054] Details of the thermal denaturation gelation process in the presence of water and in the absence of a coagulant, which is the application of the gelling agent of the present invention, are as described in "1-2. Thermal Denaturation Gelation Process" above.

[0055] The gelling agent of the present invention may consist of a modified plant protein having a deamidated side chain as the active ingredient, or it may contain other components as long as they do not impair the effects of the present invention. Examples of other components include additives and bases.

[0056] Examples of additives and bases include excipients, buffers, antioxidants, UV inhibitors, preservatives, pH adjusters, dispersants, emulsifiers, solubilizers, solvents (especially water), vitamins, and seasonings (sweeteners, etc.). These additives and bases may be used individually or in combination of two or more. The content of these additives and bases may be appropriately determined depending on the formulation form of the gelling agent.

[0057] The properties of the gelling agent of the present invention are not particularly limited, but examples include dry formulations such as powders, fine granules, granules, and blocks, as well as liquid formulations.

[0058] 4. Gel stress modifier The gel stress modifier of the present invention comprises a protein deamidation enzyme and is characterized by being used to modify the gel stress of a plant protein coagulant-free, heat-denatured hydrogel.

[0059] The protein deamidase, which is the active ingredient of the gel stress modifier of the present invention, is as described in "1-1-2. Protein Deamidase" above.

[0060] The method for modifying the gel stress of a plant protein hydrogel without a coagulant, which is an application of the gel stress modifier of the present invention, is as described in "1. Method for modifying the gel stress of a plant protein hydrogel" above.

[0061] The gel stress modifier of the present invention may consist of a protein deamidase as the active ingredient, or it may contain other components as long as they do not impair the effects of the present invention. Examples of other components include additives and bases.

[0062] Examples of additives and bases include excipients, buffers, antioxidants, UV inhibitors, preservatives, antimicrobial agents, pH adjusters, dispersants, emulsifiers, solubilizers, and solvents (especially water). These additives and bases may be used individually or in combination of two or more. The content of these additives and bases may be appropriately determined depending on the formulation form of the gel stress modifier.

[0063] The properties of the gel stress modifier of the present invention are not particularly limited, but examples include dry formulations such as powders, fine granules, and granules, and liquid formulations.

[0064] 5. Food and beverages The food and beverages of the present invention are characterized by containing a heat-denatured hydrogel without a coagulant, which is a modified plant protein having a deamidated side chain.

[0065] The hydrogels contained in the food and beverages of the present invention exhibit increased or decreased gel stress compared to unmodified plant protein coagulant-free, heat-denatured hydrogels. Therefore, the food and beverages of the present invention encompass a wide range of foods and beverages with varying gel stress levels.

[0066] Examples of food and beverages include plant-based cheese, plant-based yogurt, plant-based cream (in the form of whipped cream or non-whipped cream), plant-based ice cream, foods containing alternative meat (in the form of processed meat such as hamburgers, meatballs, patties, meatloaf, and minced cutlets; in the form of fish paste products such as kamaboko, chikuwa, hanpen, datemaki, and fish sausage), foods containing alternative eggs (in the form of boiled eggs, onsen tamago, poached eggs, scrambled eggs, fried eggs, thick omelets, rolled omelets, egg toppings for Tenshindon, egg drop soup, egg drop soup, quiche, omelet, thin omelet (omelet rice sheet, shredded egg), chawanmushi, egg tofu, pudding, cake, mayonnaise, custard cream, liquid egg, etc.), and various liquid foods and beverages (in the form of sauces (pasta sauce, etc.), soups, curries, stews, etc.).

[0067] Furthermore, the food and beverages may not only be for healthy individuals, but also for infants, toddlers, patients receiving medical treatment, and those requiring care. In other words, examples of food and beverages include weaning foods, toddler foods, therapeutic foods, and care foods. For these food and beverages, it is preferable to use a hydrogel with reduced gel stress than an unmodified, heat-denatured hydrogel made from plant-based protein without a coagulant.

[0068] Furthermore, the food and beverages may be intended not only for humans but also for other mammals.

[0069] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples.

[0070] As plant protein materials, the following powders were used, which were obtained by removing components other than protein from various types of calabash to purify or crudely purify the protein.

[0071] The enzyme used was protein glutaminase derived from Chryseobacterium proteolyticum, manufactured by Amano Enzyme Co., Ltd. (hereinafter also referred to as "PG").

[0072] Protein deamidase activity was measured by the following method: 0.1 mL of sample solution containing protein deamidase was added to 1 mL of 0.2 M phosphate buffer (pH 6.5) containing 30 mM Z-Gln-Gly, and after standing at 37°C for 10 minutes, 1 mL of 0.4 M TCA solution was added to stop the reaction. As a blank, 1 mL of 0.4 M TCA solution was added to 1 mL of 0.2 M phosphate buffer (pH 6.5) containing 30 mM Z-Gln-Gly, and then 0.1 mL of sample solution containing protein deamidase was added and left to stand at 37°C for 10 minutes.

[0073] The amount of ammonia produced in the reaction solution was measured using the Ammonia Test Wako (Fujifilm Wako Pure Chemical Industries, Ltd.) for the solution obtained as described above. The ammonia concentration in the reaction solution was determined from a calibration curve showing the relationship between ammonia concentration and absorbance (630 nm) prepared using an ammonia standard solution (ammonium chloride).

[0074] The activity of the protein deamidase was calculated using the following formula, with one unit (1 U) defined as the amount of enzyme that produces 1 μmol of ammonia per minute. In the formula, the reaction volume is 2.1, the enzyme solution volume is 0.1, and Df is the dilution ratio of the enzyme solution. Also, 17.03 is the molecular weight of ammonia.

[0075]

[0076] Test Example 1 A plant protein suspension (plant protein mixture, pH approximately 7 (25°C)) was prepared by suspending a plant protein material in water to a final concentration of 5% by weight (final concentration of plant protein: 2.5–5% by weight). 5 U of PG per gram of plant protein material (5–10 U per gram of plant protein) was added, and the mixture was incubated at 50°C for 16 hours. Subsequently, the PG was deactivated by boiling for 5 minutes. This yielded a deamidated protein suspension. The deamidated protein suspension was further freeze-dried to obtain a deamidated protein powder.

[0077] Deamidated protein powder was suspended in deionized water to a final concentration of 20% by weight. Hydrochloric acid and / or sodium hydroxide were used as pH adjusters to adjust the pH (25°C) to 4.0, 5.0, 5.5, 6.0, 6.5, 7.0, or 8.0. The mixture was then boiled for 15 minutes to prepare thermally denatured gels of each PG-treated plant protein. Meanwhile, thermally denatured gels of controls for each plant protein were prepared by performing the same procedure as above, except that PG was not added, for each pH condition.

[0078] The gel stress of the obtained thermally denatured gels was measured using a rheometer (manufactured by Sun Science Co., Ltd.). For each type of plant protein, the gel stress measurement value of the thermally denatured gel of the PG-treated plant protein was divided by the gel stress measurement value of the control thermally denatured gel, and the result was multiplied by 100 to obtain the relative gel stress value (%). The relative gel stress values ​​are shown in Tables 2A to 2C. In Tables 2A to 2C, the relative gel stress value when the control did not gel and only the PG-treated plant protein gelled is indicated as "+++", and the relative gel stress value when neither the control nor the PG-treated plant protein gelled is indicated as "XXX".

[0079]

[0080]

[0081]

[0082] In all cases, the gel stress of the heat-denatured gels changed after PG treatment. Except for chickpea protein, the gel stress of the heat-denatured gels increased when heat-denatured at pH 5, and decreased when heat-denatured at pH 6.

[0083] Furthermore, the gel stress of the heat-denatured gel increased or decreased depending on the type of plant protein and the specific pH at which the gel was denatured.

[0084] For pea protein, thermal denaturation gelation at pH 8.0, 7.0, 6.5, and 5.0 increased the gel stress of the thermally denatured gel, while thermal denaturation gelation at pH 6.0, 5.5, and 4.0 decreased the gel stress of the thermally denatured gel. For soy protein, thermal denaturation gelation at pH 8.0, 7.0, 6.5, 5.0, and 4.0 increased the gel stress of the thermally denatured gel, while thermal denaturation gelation at pH 6.0 and 5.5 decreased the gel stress of the thermally denatured gel.

[0085] Lupin bean protein and broad bean protein showed reduced gel stress in the heat-denatured gels upon thermal denaturation gelation at pH 8.0, 7.0, 6.0, 5.5, and 4.0, while increased gel stress in the heat-denatured gels upon thermal denaturation gelation at pH 5.0. Mung bean protein and lentil protein also showed reduced gel stress in the heat-denatured gels upon thermal denaturation gelation at pH 8.0, 7.0, 6.0, and 4.0, while increased gel stress in the heat-denatured gels upon thermal denaturation gelation at pH 5.5 and 5.0.

[0086] Chickpea protein underwent thermal denaturation gelation at pH 8.0, 7.0, 6.0, and 5.5, resulting in increased gel stress.

Claims

1. A method for modifying the gel stress of a thermally denatured gel of a plant protein, comprising a thermal denaturation gelation step of thermally denaturing a modified plant protein having deamidated side chains in the presence of water and in the absence of a coagulant.

2. The method according to claim 1, wherein the thermal denaturation gelation step is carried out under any of the following conditions (I) to (V), and the gel stress modification is an increase in gel stress: (I) the plant protein is pea protein and the pH condition is 4.8 to 5.2 or 6.3 to 8.2, (II) the plant protein is soy protein and the pH condition is 3.8 to 5.2 or 6.3 to 8.2, (III) the plant protein is lupin bean protein and / or broad bean protein and the pH condition is 4.8 to 5.2, (IV) the plant protein is mung bean protein and / or lentil protein and the pH condition is 4.8 to 5.7, and (V) the plant protein is chickpea protein and the pH condition is 5.3 to 8.

2.

3. The method according to claim 1, wherein the thermal denaturation gelation step is carried out under any of the following conditions (i) to (iv), and the gel stress modification is gel stress reduction: (i) the plant protein is pea protein and the pH condition is 3.8 to 4.2 or 5.3 to 6.2, (ii) the plant protein is soy protein and the pH condition is 5.3 to 6.2, (iii) the plant protein is lupin bean protein and / or broad bean protein and the pH condition is 3.8 to 4.2 or 5.3 to 8.2, and (iv) the plant protein is mung bean protein and / or lentil protein and the pH condition is 3.8 to 4.2 or 5.8 to 8.

2.

4. The method according to claim 1, wherein the modified plant protein is a product of treating a plant protein with protein glutaminase.

5. A method for producing a thermally denatured gel of a modified plant protein, comprising a thermal denaturation gelation step of thermally denaturing a modified plant protein having a deamidated side chain in the presence of water and in the absence of a coagulant.

6. The manufacturing method according to claim 5, wherein the modified plant protein is a product of processing a plant protein with protein glutaminase.

7. A gelling agent for thermal denaturation gelation in the presence of water and in the absence of a coagulant, comprising a modified plant protein having a deamidated side chain.

8. The gelling agent according to claim 7, wherein the side chain is a side chain amide group of a glutamine residue.

9. A gel stress modifier for plant protein coagulants, containing a protein deamide enzyme, for heat-denatured hydrogels.

10. Food and beverages containing a heat-denatured hydrogel, a coagulant made from modified plant proteins with deamidated side chains.

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