Method for producing a liquid composition containing processed plant protein

Abstract

The purpose of the present invention is to provide a processing technology that exhibits an excellent solubilization effect on a plant-derived protein-containing liquid composition. This method for producing a plant-derived processed protein-containing liquid composition comprises a step for processing a plant-derived protein-containing liquid composition by using a protein deamidase and a protease. The plant-derived processed protein-containing liquid composition obtained from said production method has increased solubility.

Description

Technical Field

[0001] The present invention relates to a method for producing a liquid composition containing processed vegetable protein, and more specifically, to a method for producing a liquid composition containing vegetable protein processed to improve solubility.

Background Art

[0002] In recent years, due to various backgrounds such as the health boom, dealing with allergy problems, religious reasons, and the increasing opportunities for self-restraint from going out due to the spread of infectious diseases, as an alternative to animal milk, plant-based protein beverages rich in nutrition and having a long shelf life have become increasingly popular.

[0003] On the other hand, vegetable proteins generally have lower solubility and the like compared to the proteins contained in animal milk, so their uses are inevitably limited. For this reason, plant-based milk has not yet been able to fully keep up as an alternative to animal milk, and its utilization or application has not been fully considered.

[0004] As a method for improving the solubility of vegetable proteins, deamidation, that is, hydrolyzing the amide group in the side chain of glutamine residues or asparagine residues in proteins, is known as an effective method. For example, Patent Document 1 shows that by treating plant-based milk with a protein deamidase, aggregation when added to high-temperature liquid foods and drinks can be suppressed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] To penetrate the general market more widely and deeply with plant-based protein beverages (liquid compositions containing plant-based protein), further improvements in processing technology are desired. The inventors focused on solubility as a characteristic of plant-based protein-containing liquid compositions that should be controlled by such processing technology. However, currently, no processing technology is known that provides a satisfactory solubilization effect for plant-based protein-containing liquid compositions.

[0007] Therefore, the present invention aims to provide a processing technology that exhibits an excellent solubilization effect on liquid compositions containing plant proteins. [Means for solving the problem]

[0008] The inventors have discovered that treating a liquid composition containing plant protein with protease and protein deamidase dramatically improves its solubility. Furthermore, they unexpectedly discovered that using a specific protease can suppress changes in taste while improving solubility. This invention was completed by further investigation based on these findings.

[0009] In other words, the present invention provides inventions in the following embodiments. Item 1. A method for producing a processed plant protein-containing liquid composition, comprising the step of treating a plant protein-containing liquid composition with a protease and a protein deamidation enzyme. Item 2. The method for producing the plant protein-containing liquid composition, wherein the composition is treated with the protease and then with the protein deamidation enzyme, as described in Item 1. Item 3. The method for producing a protease according to item 1 or 2, wherein the protease is a protease derived from a filamentous fungus. Item 4. The manufacturing method according to any one of items 1 to 3, wherein the protease is derived from Aspergillus oryzae. Item 5. The method for producing a product according to any one of items 1 to 4, wherein the plant protein is a plant protein selected from the group consisting of oats, peas, chickpeas, rice, and almonds. Item 6. The method for producing a plant-based protein-containing liquid composition according to items 1 to 5, wherein the plant-based protein-containing liquid composition is plant-based milk. Item 7. A solubilizer for a plant protein-containing liquid composition, comprising a protease and a protein deamide enzyme. Item 8. A solubilizing agent containing a neutral protease, used to solubilize a plant protein-containing liquid composition treated with a protein deamidation enzyme while suppressing changes in taste. Item 9. A solubilizing agent used to solubilize a plant protein-containing liquid composition that contains a protease derived from filamentous fungi and is treated with a protein deamide enzyme, while suppressing changes in taste. [Effects of the Invention]

[0010] The present invention provides a processing technology that exhibits an excellent solubilizing effect on liquid compositions containing plant proteins. [Modes for carrying out the invention]

[0011] 1. Method for producing a liquid composition containing processed plant protein The present invention relates to a method for producing a processed plant protein-containing liquid composition, characterized by comprising the step of treating the plant protein-containing liquid composition with a protease and a protein deamidation enzyme. The method for producing the processed plant protein-containing liquid composition of the present invention will be described in detail below.

[0012] 1-1. Liquid composition containing plant protein The plant protein-containing liquid composition used in the present invention is not particularly limited as long as it is a liquid in which plant protein is dissolved and / or dispersed in water. Specific examples of plant protein-containing liquid compositions include: (i) a liquid obtained by dispersing a dried powder of a plant protein-containing material (preferably a plant food material) in water; (ii) a liquid obtained by crushing and dispersing a plant protein-containing material (preferably a plant food material) in water, and removing insoluble matter derived from the peel of the food material, etc., by any means such as centrifugal filtration, filtration, filter bag, sieve, etc.; (iii) a liquid obtained by increasing the plant protein content from the liquid of (i) or (ii) by removing components other than plant protein, etc.; and (iv) a liquid obtained by dissolving and / or dispersing a dried powder prepared from any of the liquids of (i) to (iii) in water.

[0013] While not particularly limited, examples of plant-based proteins include cereals such as oats, barley, wheat, rice, buckwheat, millet, foxtail millet, teff, and quinoa; legumes such as soybeans, peas, lupin beans, broad beans, and chickpeas; and plant proteins (plant-based food ingredients) such as canary seeds, flaxseed, almonds, cashews, hazelnuts, pecans, macadamia nuts, pistachios, walnuts, Brazil nuts, peanuts, coconuts, chestnuts, sesame seeds, and pine nuts. These plant proteins may be used individually or in combination.

[0014] Among these plant-based proteins, oat, pea, chickpea, rice, and almond proteins are preferred from the viewpoint of further enhancing the solubility-improving effect. Furthermore, when using a protease derived from filamentous fungi as the protease, pea, chickpea, rice, and almond proteins are preferred from the viewpoint of further enhancing the solubility-improving effect and / or the effect of suppressing changes in taste.

[0015] A preferred example of a liquid composition containing plant protein is plant-based milk prepared from plant-based food materials. Preferred examples of plant-based milk, from the viewpoint of further enhancing the solubility-improving effect, are preferably oat milk, pea milk, chickpea milk, rice milk, and almond milk. As for oat milk, an example is oat milk in the form of a heat-treated oat slurry, and the temperature of the heat treatment is, for example, 55 to 100°C, preferably 57 to 80°C, more preferably 59 to 70°C, and even more preferably 59 to 65°C. Furthermore, when using a protease derived from filamentous fungi as the protease, from the viewpoint of further enhancing the solubility-improving effect and / or the effect of suppressing changes in taste, preferred plant-based milks are preferably pea milk, chickpea milk, rice milk, and almond milk.

[0016] The protein content in the plant protein-containing liquid composition used in the present invention is not particularly limited.

[0017] Examples of protein content in a liquid composition containing plant protein include 0.1 to 8% by weight, preferably 0.5 to 5% by weight. More specifically, the oat protein content in a liquid composition containing oat protein is preferably 0.5 to 4% by weight, more preferably 1 to 3% by weight; the pea protein content in a liquid composition containing pea protein is preferably 1 to 5% by weight, more preferably 2 to 4% by weight; the chickpea protein content in a liquid composition containing chickpea protein is preferably 0.5 to 4% by weight, more preferably 1 to 3% by weight; the rice protein content in a liquid composition containing rice protein is preferably 0.5 to 4% by weight, more preferably 1 to 3% by weight; and the almond protein content in a liquid composition containing almond protein is preferably 1 to 5% by weight, more preferably 2 to 4% by weight.

[0018] As other examples of the protein content in the liquid composition containing vegetable protein, the amount of water used per 1 part by weight of the material containing vegetable protein (preferably a vegetable food material) is, for example, 2 to 30 parts by weight, preferably 3 to 25 parts by weight, more preferably 6 to 12 parts by weight. More specifically, as the content of oat protein in the liquid composition containing oat protein, the amount of water used per 1 part by weight of oats (in terms of the whole oat grains) is, for example, 6 to 12 parts by weight, preferably 8 to 10 parts by weight, more preferably 8.5 to 9.5 parts by weight.

[0019] In addition, as the liquid composition containing cereal vegetable protein, from the viewpoint of improving the solubility of the processed liquid composition containing vegetable protein produced by the present invention, it is preferable to use the one treated with α - amylase. The α - amylase is not particularly limited, and examples include α - amylases derived from the genus Aspergillus and the genus Bacillus. Preferably, it is derived from the genus Bacillus, such as Bacillus subtilis, Bacillus amyloliquefaciens, Bacillus licheniformis. More preferably, the α - amylase of Bacillus amyloliquefaciens is mentioned. The amount of α - amylase used per 1 part by weight of cereals (in terms of the whole cereal grains) is, for example, 5 to 300 U. When the cereals are oats, the amount of α - amylase used per 1 part by weight of oats (in terms of the whole oat grains) is, for example, 5 to 300 U, preferably 10 to 150 U, more preferably 20 to 70 U, still more preferably 30 to 50 U. Regarding the activity of α - amylase, the amount of enzyme that reduces the color development of potato starch by iodine by 10% in 1 minute is defined as 1 unit (1 U).

[0020] 1-2. Protein deamidation enzymes As the protein deamidase used in the present invention, it is an enzyme that exhibits the action of decomposing the amide group-containing side chain of a protein without involving the cleavage of peptide bonds and the cross-linking of proteins, and the type, origin, etc. thereof are not particularly limited. Further, as long as the above action is the main activity, it may further have the action of decomposing the amide group-containing side chain of a protein involving the cleavage of peptide bonds and the cross-linking of proteins.

[0021] Examples of protein deamidases 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 deamidases include protein deamidases derived from the genus Chryseobacterium, Flavobacterium, Empedobacter, Sphingobacterium, Aureobacterium, or Myroides, the genus Luteimicrobium, Agromyces, Microbacterium, or Leifsonia. These protein deamidases are known, and for example, reference can be made to JP2000-50887A, JP2001-218590A, WO2006 / 075772A1, WO2015 / 133590, etc. These protein deamidases may be used alone or in combination of multiple types.

[0023] Among these protein deamide enzymes, from the viewpoint of further improving the solubilization effect, or in addition to further improving the ability to suppress changes in taste, protein deamide enzymes derived from the genus Chryseobacterium are preferred, 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] Commercially available products can also be used as protein deamide enzymes. A preferred example of a commercially available product is "Amano" 500 protein glutaminase (derived from Chryseobacterium proteoricum) manufactured by Amano Enzyme Co., Ltd.

[0026] The amount of protein deamidase used is not particularly limited, but for example, 0.01 U or more per gram of plant protein is used. From the viewpoint of further improving the solubilization effect, or in addition to further improving the ability to suppress changes in taste, the amount of protein deamidase used per gram of plant protein is preferably 0.05 U or more, 0.1 U or more, more preferably 0.5 U or more, even more preferably 0.8 U or more, even more preferably 1 U or more, and even more preferably 1.5 U or more, 2 U or more, 2.5 U or more, and 2.8 U or more. The upper limit of the range of the amount of protein deamidase used per gram of plant protein is not particularly limited, but for example, 40 U or less, 30 U or less, 20 U or less, 15 U or less, 10 U or less, 5 U or less, 4 U or less, 3.2 U or less, and 3 U or less is used.

[0027] More specifically, when the plant protein is an autoprotein, from the viewpoint of further improving the solubilization effect, or in addition to further improving the ability to suppress changes in taste, preferred amounts of protein deamidase per gram of autoprotein include, for example, 0.1U or more, 0.5U or more, or 1U or more, preferably 1.5U or more, more preferably 2U or more, even more preferably 2.5U or more, and even more preferably 2.8U or more. Preferred upper limits for the range of amounts of protein deamidase per gram of autoprotein include, for example, 40U or less, 30U or less, 20U or less, 10U or less, 5U or less, 4U or less, or 3.2U or less.

[0028] When the plant protein is pea protein, chickpea protein, rice protein, and / or almond protein, from the viewpoint of further improving the solubilization effect, or in addition to further improving the ability to suppress changes in taste, a preferred amount of protein deamidation enzyme per gram of these plant proteins is, for example, 0.1 U or more, 0.5 U or more, or 1 U or more, preferably 1.5 U or more, and more preferably 2 U or more. A preferred upper limit for the range of the amount of protein deamidation enzyme used per gram of these plant proteins is, for example, 40 U or less, 30 U or less, 20 U or less, 10 U or less, 5 U or less, 4 U or less, or 3 U or less.

[0029] Furthermore, the amount of protein deamide enzyme used per gram of plant protein material can be, for example, 0.001 U or more. From the viewpoint of further improving the solubilization effect of the plant protein-containing liquid composition, or in addition to that, further improving the ability to suppress changes in taste, preferred amounts of protein deamide enzyme used per gram of plant protein material can be, 0.005 U or more, 0.01 U or more, more preferably 0.05 U or more, 0.1 U or more, 0.15 U or more, 0.3 U or more, 0.35 U or more, 0.4 U or more, 0.5 U or more, 1 U or more, and 1.5 U or more. There is no particular upper limit to the range of amounts of protein deamide enzyme used per gram of plant protein material, but examples include 20 U or less, 10 U or less, 5 U or less, 4 U or less, 3 U or less, 2 U or less, 1.5 U or less, 1 U or less, 0.6 U or less, 0.5 U or less, 0.45 U or less, 0.4 U or less, and 0.3 U or less.

[0030] More specifically, when the plant protein is an autoprotein, from the viewpoint of further improving the solubilization effect, or in addition to further improving the ability to suppress changes in taste, a preferred amount of protein deamide enzyme per gram of auto (in terms of whole grains of auto) is, for example, 0.05 U or more, preferably 0.1 U or more, more preferably 0.15 U or more, even more preferably 0.3 U or more, and even more preferably 0.35 U or more. A preferred upper limit for the range of the amount of protein deamide enzyme used per gram of auto (in terms of whole grains of auto) is, for example, 4 U or less, 3 U or less, 2 U or less, 1 U or less, 0.6 U or less, 0.4 U or less, or 0.45 U or less.

[0031] More specifically, when the plant protein is rice protein, from the viewpoint of further improving the solubilization effect, or in addition to further improving the ability to suppress changes in taste, a preferred amount of protein deamide enzyme per gram of rice (in terms of dry brown rice flour) is, for example, 0.01 U or more, or 0.05 U or more, preferably 0.1 U or more, and more preferably 0.15 U or more. A preferred upper limit for the range of the amount of protein deamide enzyme used per gram of rice (in terms of dry brown rice flour) is, for example, 2 U or less, 1 U or less, 0.5 U or less, or 0.3 U or less.

[0032] When the plant protein is almond protein, from the viewpoint of further improving the solubilization effect, or in addition to further improving the ability to suppress changes in taste, a preferred amount of protein deamidation enzyme per gram of almond (in terms of almond powder) is, for example, 0.05 U or more, or 0.1 U or more, preferably 0.3 U or more, and more preferably 0.4 U or more. A preferred upper limit for the range of the amount of protein deamidation enzyme used per gram of almond (in terms of almond powder) is, for example, 5 U or less, 4 U or less, 2 U or less, 1 U or less, or 0.6 U or less.

[0033] When the plant protein is chickpea protein, from the viewpoint of further improving the solubilization effect, or in addition to further improving the ability to suppress changes in taste, a preferred amount of protein deamidation enzyme per gram of chickpea is, for example, 0.05 U or more, or 0.1 U or more, preferably 0.3 U or more, and more preferably 0.4 U or more. A preferred upper limit for the range of the amount of protein deamidation enzyme used per gram of chickpea is, for example, 5 U or less, 4 U or less, 2 U or less, 1 U or less, or 0.6 U or less.

[0034] When the plant protein is pea protein, from the viewpoint of further improving the solubilization effect, or in addition to further improving the ability to suppress changes in taste, a preferred amount of protein deamidase per gram of pea is, for example, 0.2 U or more, or 0.5 U or more, preferably 1 U or more, and more preferably 1.5 U or more. A preferred upper limit for the range of the amount of protein deamidase used per gram of pea is, for example, 20 U or less, 10 U or less, 5 U or less, or 3 U or less.

[0035] For the activity of protein deamidase enzymes, one unit (1 U) of enzyme is defined as the amount of enzyme that converts 1 μmol of ammonia per minute using benzyloxycarbonyl-L-glutaminylglycine (Z-Gln-Gly) as the substrate.

[0036] 1-3. Proteases The protease used in the present invention is not particularly limited as long as it is an enzyme that hydrolyzes the peptide bonds of proteins.

[0037] According to classifications based on origin, proteases include those derived from filamentous fungi and those derived from bacteria. Either one of these proteases may be used, or both may be used in combination.

[0038] The filamentous fungal protease is not particularly limited as long as it can achieve the desired effects of the present invention. Specific examples of filamentous fungal proteases include those derived from the genera Aspergillus, Mucor, Neurospora, Penicillium, Rhizomucor, Rhizopus, and Sclerotinia. These filamentous fungal proteases may be used individually or in combination.

[0039] Specific examples of proteases derived from the genus Aspergillus include Aspergillus oryzae, Aspergillus niger, Aspergillus melleus, Aspergillus japonicus, Aspergillus awamori, Aspergillus kawachii, Aspergillus sojae, Aspergillus tamarii, Aspergillus foetidus, Aspergillus fumigatus, and Aspergillus nidurans. Aspergillus nidulans), Aspergillus aculeatus, Aspergillus candidus, Aspergillus flavus, Aspergillus saitoi, Aspergillus inuii, Aspergillus glaucus, Aspergillus caesiellus, Aspergillus clavatus, Aspergillus deflectus, Aspergillus fischerianus, Aspergillus parasiticus, Aspergillus penicilloides (Aspergillus Aspergillus penicilloides), Aspergillus restrictus, Aspergillus sydowii, Aspergillus terreus, Aspergillus ustus (AspergillusExamples include proteases derived from Aspergillus versicolor, etc. These Aspergillus-derived proteases may be used individually or in combination of multiple species.

[0040] Examples of bacterial proteases include those derived from the Bacillus genus (or Geobacillus genus), etc. These bacterial proteases may be used individually or in combination of multiple types.

[0041] Specific examples of proteases derived from the genus Bacillus (or Geobacillus) include Bacillus amyloliquefaciens, Bacillus cereus, Bacillus clausii, Bacillus intermedius, Bacillus lentus, Bacillus licheniformis, Bacillus stearothermophilus, Bacillus subtilis, and Bacillus thermoproteolyticus, as well as proteases derived from these Geobacillus species. Among these proteases derived from the Bacillus genus (or Diobacillus genus), Bacillus stearothermophilus-derived proteases are preferred, and Diobacillus stearothermophilus-derived proteases are preferred, from the viewpoint of further improving the solubilizing effect of plant protein-containing liquid compositions.

[0042] Among the above-mentioned proteases, from the viewpoint of further enhancing the solubility-improving effect, filamentous fungal-derived proteases and bacterial-derived proteases are preferred. Among the above-mentioned proteases, from the viewpoint of further obtaining a taste change suppression effect, filamentous fungal-derived proteases are preferred. When the plant protein is an oat protein, from the viewpoint of further enhancing the solubility-improving effect and / or further obtaining a taste change suppression effect, it is preferable to use either filamentous fungal-derived proteases or bacterial-derived proteases. When the plant protein is pea protein, chickpea protein, rice protein, and / or almond protein, from the viewpoint of further enhancing the taste change suppression effect, or in addition to further enhancing the solubility-improving effect, it is more preferable to use filamentous fungal-derived proteases.

[0043] Among the above-mentioned filamentous fungal proteases, from the viewpoint of further enhancing the solubility-improving effect and / or the effect of suppressing changes in taste, proteases derived from the genus Aspergillus are preferred. Furthermore, among the above-mentioned proteases derived from the genus Aspergillus, from the viewpoint of further enhancing the solubility-improving effect and / or the effect of suppressing changes in taste, proteases derived from Aspergillus oryzae are preferred. In addition, when the plant protein is an autoprotein, among the above-mentioned proteases derived from the genus Aspergillus, from the viewpoint of further enhancing the solubilizing effect of the plant protein-containing liquid composition, proteases derived from Aspergillus niga and Aspergillus oryzae are preferred, and more preferably, proteases derived from Aspergillus oryzae are preferred.

[0044] When classifying proteases based on their optimal pH, examples include acidic proteases, neutral proteases, and alkaline proteases. One of these proteases may be used, or two or more may be used in combination. Among these proteases, acidic proteases and neutral proteases are preferred. When the plant protein is an autoprotein, among these proteases, from the viewpoint of further improving the solubilization effect, preferred proteases are acidic proteases (such as Aspergillus niga-derived protease) and neutral proteases (such as Aspergillus oryzae-derived protease), more preferably neutral proteases, and even more preferably Aspergillus oryzae-derived neutral proteases. Furthermore, when the plant protein is an autoprotein, among these proteases, from the viewpoint of obtaining an effect of suppressing changes in taste, a neutral protease (such as Aspergillus oryzae-derived protease) is preferred, and more preferably, Aspergillus oryzae-derived neutral protease is preferred. When the plant protein is pea protein, chickpea protein, rice protein, and / or almond protein, among the proteases, from the viewpoint of further enhancing the solubility-improving effect and / or the effect of suppressing changes in taste, a neutral protease and an acidic protease are preferred, and in some cases (for example, when the plant protein is rice protein, almond protein, or chickpea protein), a neutral protease is preferred.

[0045] Examples of proteases, according to classification based on catalytic mechanism, include serine proteases, metalloproteases, thiol proteases, and aspartate proteases. One of these proteases may be used, or two or more may be used in combination.

[0046] Proteases can be prepared by known methods. For example, they can be easily prepared by culturing the microorganism from which the protease is derived and isolating the produced protease using known means, or by using genetic engineering technology. Commercially available proteases may also be used. Examples of commercially available proteases include Protease M "Amano" (acidic protease derived from Aspergillus oryzae), Protease HF "Amano" 150SD (acidic protease derived from Aspergillus oryzae), Protease A "Amano" (neutral protease derived from Aspergillus oryzae), Protease A "Amano" 2SD (neutral protease derived from Aspergillus oryzae), and Acidic Protease UF "Amano" SD (acidic protease derived from Aspergillus niga). Examples include proteases, protease N "Amano" G (neutral protease derived from Bacillus subtilis), protin SD-NY10 (neutral protease derived from Bacillus amyloricephaciens), samoase PC10F (neutral protease derived from Bacillus stearothermophilus); and from Shin Nippon Chemical Industries, Ltd., Sumizyme MP (alkaline protease derived from Aspergillus meleus) and Sumizyme FP-G (alkaline protease derived from Aspergillus oryzae).

[0047] The amount of protease used is not particularly limited, but examples of amounts used per gram of plant protein include 0.0005 U or more, and 0.001 U or more. From the viewpoint of further improving the solubilization effect, or in addition to that, further improving the ability to suppress changes in taste, preferred amounts of protease used per gram of plant protein include 0.003 U or more, 0.005 U or more, 0.01 U or more, 0.03 U or more, 0.05 U or more, 0.1 U or more, 0.2 U or more, 0.5 U or more, 1 U or more, 2 U or more, 3 U or more, 4 U or more, 6 U or more, 8 U or more, and 10 U or more. There is no particular upper limit to the amount of protease used per gram of plant protein, but examples include 100U or less, 90U or less, 80U or less, 70U or less, 65U or less, 60U or less, 50U or less, 40U or less, 30U or less, 20U or less, 15U or less, 10U or less, 8U or less, 7U or less, and 6U or less.

[0048] When the plant protein is an autoprotein, from the viewpoint of further improving the solubilization effect and / or further improving the ability to suppress changes in taste, a preferred amount of protease to be used per gram of autoprotein is, for example, 0.01 U or more or 0.03 U or more, preferably 0.05 U or more, 0.1 U or more, or 0.2 U or more, more preferably 0.5 U or more, 1 U or more, or 2 U or more, even more preferably 4 U or more, 6 U or more, 8 U or more, or 10 U or more. From the viewpoint of further improving the solubilization effect, a preferred upper limit for the range of protease used per gram of autoprotein is, for example, 100 U or less, 90 U or less, 80 U or less, or 70 U or less, preferably 65 U or less, more preferably 40 U or less, even more preferably 30 U or less, even more preferably 20 U or less, and even more preferably 15 U or less, 10 U or less, or 7 U or less.

[0049] When the plant protein is pea protein, chickpea protein, rice protein, and / or almond protein, from the viewpoint of further improving the solubilization effect and / or further improving the ability to suppress changes in taste, preferred amounts of protease per gram of these plant proteins include, for example, 0.0005U or more, 0.003U or more, preferably 0.005U or more, 0.01U or more, 0.03U or more, more preferably 0.05U or more, even more preferably 0.1U or more, even more preferably 0.5U or more, 1U or more, 3U or more, and 4U or more. From the viewpoint of further improving the solubilization effect and / or further improving the ability to suppress changes in taste, preferred upper limits of the amount of protease used per gram of these plant proteins include, for example, 50U or less, 30U or less, preferably 20U or less, 10U or less, more preferably 8U or less, and even more preferably 6U or less.

[0050] Furthermore, examples of the amount of protease used per gram of plant protein material include 0.0001U or more and 0.00013U or more. From the viewpoint of further improving the solubilization effect, or in addition to that, further improving the ability to suppress changes in taste, the amount of protease used per gram of plant protein material is preferably 0.0003U or more, 0.0007U or more, 0.0013U or more, 0.003U or more, 0.004U or more, 0.007U or more, and more preferably 0.008U or more, 0.01U or more, 0.025U or more, 0.05U or more, 0.07U or more, 0.1U or more, 0.25U or more, 0.5U or more, 0.75U or more, 0.8U or more, 1U or more, 1.3U or more, 2U or more, and 3U or more. There is no particular upper limit to the amount of protease used per gram of plant protein material, but examples include 20U or less, 15U or less, 11U or less, 10U or less, 8.7U or less, 8U or less, 5U or less, 4U or less, 3U or less, 2.5U or less, 2U or less, 1.5U or less, 1.3U or less, 0.9U or less, 0.5U or less, 0.3U or less, 0.1U or less, 0.05U or less, 0.03U or less, 0.01U or less, and 0.005U or less.

[0051] When the plant protein is an oat protein, from the viewpoint of further improving the solubilization effect, or in addition to further improving the ability to suppress changes in taste, a preferred amount of protease to be used per gram of oat (calculated as whole grains of oat) is, for example, 0.002U or more or 0.004U or more, preferably 0.007U or more, 0.01U or more, or 0.025U or more, more preferably 0.07U or more, 0.1U or more, or 0.25U or more, even more preferably 0.5U or more, 0.75U or more, 1U or more, or 1.3U or more. From the viewpoint of further improving the solubilization effect, a preferred upper limit for the amount of protease to be used per gram of oat (calculated as whole grains of oat) is, for example, 20U or less, 15U or less, or 10U or less, preferably 8.7U or less, more preferably 5U or less, even more preferably 4U or less, even more preferably 2.5U or less, even more preferably 2U or less, 1.3U or less, or 0.9U or less.

[0052] When the plant protein is rice protein, from the viewpoint of further enhancing the solubility-improving effect and / or the effect of suppressing changes in taste, a preferred amount of protease to be used per gram of rice (in terms of dry brown rice flour) is, for example, 0.0001 U or more, preferably 0.0003 U or more, and more preferably 0.003 U or more. A preferred upper limit for the range of protease used per gram of rice (in terms of dry brown rice flour) is, for example, 2 U or less, 0.5 U or less, 0.1 U or less, 0.05 U or less, 0.01 U or less, or 0.005 U or less.

[0053] When the plant protein is almond protein, from the viewpoint of further enhancing the solubility-improving effect and / or the effect of suppressing changes in taste, a preferred amount of protease to be used per gram of almond (in terms of almond powder) is, for example, 0.001 U or more, or 0.003 U or more, preferably 0.006 U or more, or 0.008 U or more. A preferred upper limit for the range of protease used per gram of almond (in terms of almond powder) is, for example, 2 U or less, 0.5 U or less, 0.1 U or less, 0.05 U or less, or 0.03 U or less.

[0054] When the plant protein is chickpea protein, from the viewpoint of further enhancing the solubility-improving effect and / or the effect of suppressing changes in taste, preferred amounts of protease per gram of chickpea include preferably 0.0003U or more, more preferably 0.003U or more, even more preferably 0.008U or more, 0.05U or more, 0.1U or more, 0.5U or more, or 0.8U or more. Preferred upper limits for the range of protease amounts per gram of chickpea include, for example, 10U or less, 5U or less, 3U or less, 2U or less, 0.5U or less, 0.1U or less, 0.05U or less, or 0.03U or less.

[0055] When the plant protein is pea protein, from the viewpoint of further enhancing the solubility-improving effect and / or the effect of suppressing changes in taste, preferred amounts of protease per gram of pea include, for example, 0.008 U or more, more preferably 0.05 U or more, even more preferably 0.1 U or more, 0.5 U or more, 1 U or more, 2 U or more, or 3 U or more. A preferred upper limit for the range of protease amounts per gram of pea includes, for example, 50 U or less, and from the viewpoint of further enhancing the solubility-improving effect and / or the effect of suppressing changes in taste, preferred amounts include 20 U or less, 15 U or less, 12 U or less, or 10 U or less, more preferably 8 U or less, even more preferably 5 U or less, even more preferably 4 U or less, 2 U or less, 1.5 U or less, 0.5 U or less, or 0.3 U or less.

[0056] The ratio of protein deamidating enzymes to proteases used is determined based on the above usage amounts for each enzyme. However, from the viewpoint of further improving the solubilization effect, or in addition to further improving the ability to suppress changes in taste, the amount of protease used per 1U of protein deamidating enzyme can be, for example, 0.0001U or more, 0.0005U or more, 0.001U or more, more preferably 0.002U or more, 0.003U or more, 0.006U or more, 0.015U or more, 0.016U or more, 0.03U or more, 0.05U or more, 0.067U or more, 0.1U or more, 0.15U or more, 0.16U or more, 0.3U or more, 0.5U or more, 0.6U or more, 1U or more, 1.3U or more, 1.5U or more, 1.8U or more, 2U or more, 2.6U or more, or 3.3U or more. Examples of upper limits for the amount of protease protein deamide enzyme used per 1U include 50U or less, 40U or less, 33U or less, 30U or less, 26U or less, 25U or less, 20U or less, 15U or less, 13U or less, 10U or less, 8U or less, 7U or less, 5U or less, 3.5U or less, 3U or less, and 2.3U or less.

[0057] When the plant protein is an autoprotein, from the viewpoint of further improving the solubilization effect, or in addition to further improving the ability to suppress changes in taste, preferred amounts of protease protein deamidation enzyme per 1U include, for example, 0.001U or more, 0.005U or more, 0.01U or more, or 0.016U or more, preferably 0.02U or more, 0.03U or more, or 0.067U or more, more preferably 0.16U or more, 0.3U or more, or 0.6U or more, and even more preferably 1.3U or more, 2U or more, 2.6U or more, or 3.3U or more. From the viewpoint of further improving the solubilization effect, a preferred upper limit for the amount of protease protein deamide enzyme used per 1U is, for example, 50U or less, 40U or less, 30U or less, or 25U or less, preferably 20U or less, more preferably 13U or less, even more preferably 10U or less, even more preferably 7U or less, and even more preferably 5U or less, 3U or less, or 2.3U or less.

[0058] When the plant protein is pea protein, chickpea protein, rice protein, and / or almond protein, from the viewpoint of further improving the solubilization effect and / or further improving the ability to suppress changes in taste, preferred amounts of protease per 1U of protein deamidation enzyme include, for example, 0.0001U or more, 0.0005U or more, or 0.001U or more, more preferably 0.0015U or more, or 0.002U or more, even more preferably 0.006U or more, even more preferably 0.015U or more, 0.05U or more, 0.1U or more, 0.15U or more, 0.5U or more, 1U or more, 1.5U or more, or 1.8U or more. A preferred upper limit for the amount of protease protein deamide enzyme used per 1U is, for example, 20U or less. From the viewpoint of further enhancing the solubility-improving effect and / or the effect of suppressing changes in taste, it is preferably 15U or less, more preferably 10U or less, even more preferably 8U or less or 7U or less, and even more preferably 5U or less or 3.5U or less.

[0059] Protease activity shall be measured using casein as a substrate and the Forin method. Specifically, protease activity is measured by the amount of enzyme that, when reacted with casein using a conventional method, produces an increase in the Forin reagent colored substance equivalent to 1 μg of tyrosine per minute, with 1 unit (1 U) being defined as the amount of enzyme.

[0060] 1-4. Reaction conditions, etc. In the process of treating a liquid composition containing plant protein with a protease and a protein deamidase, the order in which the protease and protein deamidase are applied is not particularly limited. The enzymes may be applied sequentially in any order, or both enzymes may be applied simultaneously. However, from the viewpoint of further improving the solubilization effect, it is particularly preferable to treat the liquid composition containing plant protein with a protease first, and then with a protein deamidase.

[0061] The processing temperature with protease and protein deamidase is 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-containing liquid composition, but for example, 40 to 70°C, preferably 48 to 62°C is given. Specifically, for example, the processing temperature with protein deamidase is 40 to 60°C, preferably 45 to 55°C, more preferably 48 to 52°C. For example, the processing temperature with protease is 40 to 70°C, preferably 50 to 65°C, more preferably 58 to 62°C.

[0062] The enzyme treatment reaction time for a liquid composition containing plant protein is not particularly limited and can be appropriately determined according to the preparation scale of the composition, the timing of enzyme addition, etc., but for example, 30 minutes or more, preferably 50 minutes or more. The upper limit of the enzyme treatment reaction time range is not particularly limited, but for example, 12 hours or less, 6 hours or less, 3 hours or less, 2.5 hours or less, or 2 hours or less can be cited. Specifically, for example, the treatment time with protease can be 5 minutes to 2 hours, preferably 5 minutes to 1 hour, more preferably 35 to 55 minutes or 40 minutes to 1.5 hours. Also, for the treatment time with protein deamidation enzyme, it can be 20 minutes to 6 hours, more preferably 40 minutes to 1.5 hours.

[0063] The plant protein-containing liquid composition after enzyme treatment is subjected to an enzyme deactivation step as needed, cooled, and further subjected to post-treatment steps such as filtration as needed to obtain a processed plant protein-containing liquid composition.

[0064] Furthermore, the obtained processed plant protein-containing liquid composition can be prepared as a solid plant protein composition with improved solubility in water, or in addition, suppressed changes in taste, through a drying process. The drying method is not particularly limited, but examples include freeze-drying, vacuum drying, and spray drying. The solid plant protein composition can take the form of powder, fine granules, granules, etc.

[0065] 2. Solubilizer for liquid compositions containing plant protein The combination of a protein deamidase and a protease can improve the solubility of a liquid composition containing plant proteins. Accordingly, the present invention also provides a solubilizer for a liquid composition containing plant proteins, comprising a protease and a protein deamidase.

[0066] The types of components used and the amounts used in the above-mentioned solubilizing agent are as shown in section 1, "Method for producing a liquid composition containing processed plant protein."

[0067] 3. Solubilizer for plant protein-containing liquid compositions treated with protein deamidation enzymes Neutral proteases or proteases derived from filamentous fungi can solubilize plant protein-containing liquid compositions treated with protein deamide enzymes while suppressing changes in taste. Specifically, when solubilizing plant protein-containing liquid compositions treated with protein deamide enzymes using neutral proteases or proteases derived from filamentous fungi, solubilization can be achieved without causing the taste changes that normally occur with protease treatment. Therefore, the present invention also provides a solubilizer containing neutral proteases or proteases derived from filamentous fungi, which is used to solubilize plant protein-containing liquid compositions treated with protein deamide enzymes while suppressing changes in taste.

[0068] Preferred examples of the above-mentioned solubilizers include a solubilizer containing a neutral protease used to solubilize an autoprotein-containing liquid composition treated with a protein deamide enzyme while suppressing changes in taste, and a solubilizer containing an Aspergillus oryzae-derived protease used to solubilize an autoprotein-containing liquid composition treated with a protein deamide enzyme while suppressing changes in taste.

[0069] Another preferred example of the above-mentioned solubilizer is a solubilizer used to solubilize a liquid composition containing plant protein that is treated with a protein deamidation enzyme, including a protease derived from filamentous fungi, while suppressing changes in taste, wherein the plant protein is pea protein, chickpea protein, rice protein, and / or almond protein.

[0070] In the context of the solubilizing agent described above, "solubilization" means imparting to a plant protein-containing liquid composition the property of further increasing the amount of protein that dissolves in water compared to when it is solubilized by protein deamidase alone. Furthermore, specific uses of this solubilizing agent include treating a plant protein-containing liquid composition using the solubilizing agent and protein deamidase simultaneously, treating the plant protein-containing liquid composition with the protein deamidase and then with the solubilizing agent, and treating the plant protein-containing liquid composition with the solubilizing agent and then with the protein deamidase.

[0071] The types of components used and the amounts used in the above-mentioned solubilizing agent are as shown in section 1, "Method for producing a liquid composition containing processed plant protein." [Examples]

[0072] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples.

[0073] [Enzymes used] • KSSD-8 (Clistase SD8): α-amylase derived from Bacillus amyloliquefaciens PR-ASD (Protease A "Amano" SD): Neutral protease derived from Aspergillus oryzae TH-PC10F (Samoase PC10F): Metalloprotease derived from Geobacillus stearothermophilus • PR-UFSD (Acidic Protease UF "Amano" SD): Acid protease derived from Aspergillus niger • PR-HF150SD (Protease HF "Amano" 150SD): Acid protease derived from Aspergillus oryzae • PG-500 (Protein-glutaminase "Amano" 500): Protein glutaminase (protein deamide enzyme) derived from Chryseobacterium proteolyticum.

[0074] [Method for measuring enzyme activity] (1) Method for measuring protease activity 5 mL of 0.6% (v / w) casein solution (0.05 mol / L sodium hydrogen phosphate, pH 8.0 [for TH-PC10F] or pH 6.0 [for PR-ASD]), or 0.6% (v / w) casein solution (0.7% (v / w) lactic acid, pH 3.0 [for PR-UFSD or PR-HF150SD]), was heated at 37°C for 10 minutes. Then, 1 mL of the sample solution containing protease was added and immediately mixed. After letting this solution stand at 37°C for 10 minutes, 5 mL of trichloroacetic acid reagent (trichloroacetic acid containing 1.8% trichloroacetic acid, 1.8% sodium acetate, and 0.33 mol / L acetic acid [for TH-PC10F], or 0.44 mol / L trichloroacetic acid [for PR-ASD, PR-UFSD, or PR-HF150SD]) was added and mixed. The solution was then left to stand again at 37°C for 30 minutes and filtered. After removing the first 3 mL of filtrate, 2 mL of the next filtrate was measured, and 5 mL of 0.55 mol / L sodium carbonate reagent and 1 mL of forin reagent (1→3) were added. The mixture was shaken well and left to stand at 37°C for 30 minutes. The absorbance AT of this solution (enzyme reaction solution) at a wavelength of 660 nm was measured using water as a control.

[0075] Separately, 1 mL of the sample solution containing protease was measured, and 5 mL of trichloroacetic acid reagent (trichloroacetic acid containing 1.8% trichloroacetic acid, 1.8% sodium acetate, and 0.33 mol / L acetic acid [for TH-PC10F], or 0.44 mol / L trichloroacetic acid [for PR-ASD, PR-UFSD, or PR-HF150SD]) was added and shaken. Then, 5 mL of casein solution with the measurement pH set for each sample was added, and the mixture was immediately shaken. The absorbance AB of the solution (blank), which was operated in the same manner as the enzyme reaction solution described above, except that it was left to stand at 37°C for 30 minutes, was measured.

[0076] One unit (1U) of enzyme was defined as the amount of enzyme that produces an increase in the color-developing substance in the forin reagent equivalent to 1 μg of tyrosine per minute.

[0077] 1 mL, 2 mL, 3 mL, and 4 mL of 1 mg / mL tyrosine standard stock solution (0.2 mol / L hydrochloric acid) were weighed out, and 0.2 mol / L hydrochloric acid reagent was added to each to make a total volume of 100 mL. 2 mL of each solution was weighed out, 5 mL of 0.55 mol / L sodium carbonate reagent and 1 mL of forin reagent (1→3) were added, and the mixture was immediately shaken. The solutions were then left to stand at 37°C for 30 minutes. For each of these solutions, 2 mL of 0.2 mol / L hydrochloric acid reagent was weighed out and the same procedure was followed to obtain a control solution. The absorbances A1, A2, A3, and A4 at a wavelength of 660 nm were measured. A calibration curve was created with absorbances A1, A2, A3, and A4 on the vertical axis and the amount of tyrosine (μg) in 2 mL of each solution on the horizontal axis, and the amount of tyrosine (μg) per unit of absorbance difference 1 was determined.

[0078]

number

[0079] (2) Method for measuring protein deamidase activity To 1 mL of 0.2 M phosphate buffer (pH 6.5) containing 30 mM Z-Gln-Gly, 0.1 mL of sample solution containing protein deamidase was added and left to stand at 37°C for 10 minutes. Then, 1 mL of 0.4 M TCA solution was added to stop the reaction. As a blank, 1 mL of 0.2 M phosphate buffer (pH 6.5) containing 30 mM Z-Gln-Gly was added to 1 mL of 0.4 M TCA reagent, and then 0.1 mL of sample solution containing protein deamidase was added and left to stand at 37°C for 10 minutes.

[0080] The amount of ammonia produced in the reaction solution was measured using the Ammonia Test Wako (Fujifilm Wako Pure Chemical Industries) 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 ammonia standard solution (ammonium chloride).

[0081] The activity of the protein deamide enzyme was calculated using the following formula, where 1 unit (1U) is 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.

[0082]

number

[0083] (3) α-amylase measurement method 10 mL of 1% potato starch substrate solution (0.1 mol / L acetic acid (pH 5.0)) was heated at 37°C for 10 minutes, then 1 mL of sample solution containing α-amylase was added and immediately mixed. After letting this solution stand at 37°C for 10 minutes, 1 mL of this solution was added to 10 mL of 0.1 mol / L hydrochloric acid solution and immediately mixed. Next, 0.5 mL of this solution was measured, 10 mL of 0.0002 mol / L iodine solution (Japanese Pharmacopoeia) was added and mixed, and the absorbance (AT) at a wavelength of 660 nm was measured using water as a control. Separately, the same procedure was performed by adding 1 mL of water instead of the sample solution, and the absorbance (AB) was measured. The amount of enzyme that reduces the iodine-induced coloration of potato starch by 10% in 1 minute was defined as 1 unit (1 U).

[0084]

number

[0085] [Test Example 1] (1) Method 10g of oat flour (10g of oat flour is equivalent to 10g of raw oats (whole grain). The protein content was 1.4g) and 50mg (40U / 1g of oat flour) of α-amylase KSSD-8 were added to 90mL of water and suspended. Protease PR-ASD was added in the amount shown in Table 1, stirred for 5 minutes, and then treated at 60°C for 45 minutes. After that, protein glutaminase PG-500 was added in the amount shown in Table 1, treated at 50°C for 1 hour, boiled for 10 minutes, and cooled to room temperature. Processed oat milk was obtained.

[0086] (2) Solubilization evaluation The processed oat milk obtained was centrifuged at 15,000 rpm for 15 minutes, and the supernatant was collected twice, taking care not to remove the cloudy upper layer. The protein concentration (mg / mL) of the supernatant was measured using the Bradford method. The relative protein concentration for each example was calculated, with the protein concentration in Comparative Example 1, which used a protein deamidase alone, set to 1. The results are shown in Table 1. Note that the protein concentration of processed oat milk treated similarly without using either protease or protein deamidase was approximately 0 mg / mL, but in Comparative Example 1, the protein concentration increased to over 2 mg / mL.

[0087] (3) Evaluation of the ability to suppress changes in taste Using the taste of the processed oat milk in Comparative Example 1, which was processed using a protein deamidase alone, as a baseline (creamy and milky taste was perceived), the taste of the processed oat milk in each example was compared in terms of creaminess and milkiness, and the scores corresponding to the following five items were added together to create an index of taste change suppression. The highest score on this index is +1, and the lower the score, the lower the taste change suppression. "Creamy taste" refers to the rich taste perceived when the processed oat milk is placed in the mouth, due to the combination of its fine texture and viscosity, which causes it to cling to the tongue. "Milkiness" refers to a milky flavor. The results are shown in Table 1. Note that when processed oat milk was treated in the same way without using either protease or protein deamidase, the taste was rough and no creaminess was observed. There was no change in taste... +1 point The creaminess was slightly reduced, resulting in a slightly lighter texture... -1 point The creaminess was reduced, resulting in a lighter texture... -2 points The milky flavor is slightly reduced... -1 point The milky flavor has decreased... -2 points

[0088] [Table 1]

[0089] As is clear from Table 1, treating oat milk with protease and protein deamidase further improved its solubility. Furthermore, when PR-ASD was used, the taste remained unchanged despite the improved solubility, demonstrating excellent suppression of taste changes.

[0090] [Test Example 2] Processed oat milk was prepared in the same manner as in Test Example 1, except that the enzymes shown in Table 2 were used as proteases in the indicated amounts. Solubilization and taste change inhibition were then evaluated. The results are shown in Table 2.

[0091] [Table 2]

[0092] As is clear from Table 2, treating oat milk with protease and protein deamidase further improved its solubility.

[0093] [Test Example 3] Processed oat milk was prepared in the same manner as in Test Example 1, except that the enzymes shown in Table 3 were used as proteases in the indicated amounts. Solubilization and taste change inhibition were then evaluated. The results are shown in Table 3.

[0094] [Table 3]

[0095] As is clear from Table 3, treating oat milk with protease and protein deamidase further improved its solubility.

[0096] [Test Example 4] (1) Manufacturing of processed vegetable milk (1-1) Production of processed rice milk 15 g of brown rice flour powder (7.1% protein content) was dispersed in 50 g of water, 50 mg of amylase and the types and amounts of protease shown in Table 4 were added, and the mixture was treated at 60°C for 1 hour. Then, the amount of protein deamidase shown in Table 4 was added, and the mixture was treated at 50°C for 1 hour. The treated rice milk composition was boiled for 10 minutes, cooled on ice to allow it to cool, and processed rice milk was obtained.

[0097] (1-2) Production of processed almond milk Almond milk was prepared by dispersing 10 g of almond powder (protein content 19.6% by weight) in 60 g of water. The types and amounts of protease shown in Table 4 were added, and the mixture was treated at 60°C for 80 minutes. Then, the amount of protein deamidation enzyme shown in Table 4 was added, and the mixture was treated at 50°C for 1 hour. The treated almond milk composition was boiled for 10 minutes, cooled on ice to allow it to cool, and processed almond milk was obtained.

[0098] (1-3) Production of processed chickpea milk 300g of chickpeas (20% protein content) were soaked in water overnight and then ground in a blender. The total volume was adjusted to 2,700mL with water to obtain chickpea milk. The chickpea milk was divided into 100mL portions, and the types and amounts of protease shown in Table 5 were added. After processing at 60°C for 1 hour, the amount of protein deamidation enzyme shown in Table 5 was added, and the mixture was processed at 50°C for 1 hour. The processed chickpea milk composition was boiled for 10 minutes, cooled on ice to allow it to cool, and processed chickpea milk was obtained.

[0099] (1-4) Production of processed pea milk To prepare pea milk, 10 g of pea protein material (79% by weight protein content) was mixed with 3.6 g of sunflower oil, and then water was added to adjust the total volume to 240 mL. The mixture was then homogenized at 14,000 rpm for 3 minutes. The pea milk was then mixed with the types and amounts of protease and protein deamidation enzymes shown in Table 6 and treated at 50°C for 2 hours. The treated pea milk composition was boiled for 15 minutes, cooled on ice to allow it to cool, and processed pea milk was obtained.

[0100] (2) Evaluation of the effect on improving solubility The obtained processed plant-based milk was centrifuged at 15,000 rpm for 15 minutes, and the supernatant was collected twice, taking care not to remove the cloudy upper layer. The protein (water-soluble protein) concentration (mg / mL) of the supernatant was measured using the Bradford method. The relative protein concentrations for each example were calculated, with the protein concentrations obtained in Comparative Examples 2, 3, 4, and 5, which used the protein deamidation enzyme alone, set to 1. The results are shown in Tables 4-6. In addition, the relative protein concentrations were classified according to the following criteria, and the degree of solubility improvement effect was evaluated. The results are shown in Tables 4-6. ++++ Protein relative concentration of 1.15 or higher +++ Protein relative concentration between 1.1 and 1.15 ++ Relative protein concentration 1.05 or higher and less than 1.1 + Protein relative concentration between 1 and 1.05 - Protein relative concentration less than 1

[0101] (3) Evaluation of the effect of suppressing changes in taste The taste of the processed plant-based milk from each example was compared to the taste of the processed plant-based milk from Comparative Examples 2, 3, 4, and 5, which were processed using a protein deamidation enzyme alone. A "○" indicated no change in taste, while a "×" indicated a change in taste. The results are shown in Tables 4-6.

[0102] [Table 4]

[0103] [Table 5]

[0104] [Table 6]

[0105] As is clear from the comparison between Comparative Example 2 and Examples 10 and 11, Comparative Example 3 and Example 12, Comparative Example 4 and Examples 13-16, and Comparative Example 5 and Examples 17-22, the protein solubility of plant-based milk was increased by treating it with protease and protein deamidation enzyme (Examples 10-22). Furthermore, as is clear from the comparison between Examples 10-20 and Examples 21-22, the protein solubility of plant-based milk was increased without changing the taste by treating it with filamentous fungus-derived protease and protein deamidation enzyme (Examples 10-20).

Claims

1. A solubilizing agent comprising Aspergillus oryzae-derived protease, used to solubilize plant-based milk treated with a protein deamidation enzyme while suppressing changes in taste.

2. The solubilizer according to claim 1, for use before the solubilization treatment of the plant-based milk with the protein deamidase.

3. The solubilizer according to claim 1 or 2, wherein the plant-based milk is a plant-based milk selected from the group consisting of oats, peas, chickpeas, rice, and almonds.

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