Method for producing plant protein concentrate

Abstract

To provide a means for efficiently producing plant protein concentrates for use in foods, beverages, etc. By enabling the production of plant protein concentrates with improved physical properties (particularly solubility), the utility value of plant proteins is increased, contributing to the improvement of quality in existing applications and the creation of new applications. The present invention provides a method for producing a vegetable protein concentrate, which comprises treating vegetable protein raw materials such as peas, soybeans, and almonds with a protein deamidating enzyme.

Description

[Technical Field]

[0001] The present invention relates to a plant protein concentrate. More specifically, the present invention relates to a method for producing a plant protein concentrate and uses of the product (plant protein concentrate). This application claims priority to Japanese Patent Application No. 2019-166635, filed on September 12, 2019, the entire contents of which are incorporated by reference. [Background technology]

[0002] Dairy proteins, plant proteins, and the like are used in foods and beverages to enhance nutritional value, prevent fat separation, improve water retention, improve shape retention, and improve texture. Against the backdrop of growing health consciousness in recent years, the demand and consumption of plant proteins, in particular, have increased significantly. Plant proteins are prepared into high-protein plant protein concentrates by, for example, grinding plant protein raw materials such as beans and grains, and then increasing the protein content while removing unnecessary components through alkali or acid treatment (see, for example, Non-Patent Documents 1 and 2). Concentrates with particularly high protein contents are called protein isolates (e.g., whey protein isolate), and are generally produced by further concentrating and purifying the protein concentrate using membrane concentration or the like. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-50887 [Non-patent literature]

[0004] [Non-Patent Document 1] Int J Mol Sci. 2011; 12(12): 8372-8387. [Non-patent document 2] JOURNAL OF FOOD SCIENCE Vol.46 372 (1981) Summary of the Invention [Problem to be solved by the invention]

[0005] The demand and consumption of plant proteins is expected to continue to increase, making it desirable to provide plant protein concentrates at low cost. Furthermore, plant proteins have high potential value due to their characteristics (especially their compatibility with health-conscious trends), and their uses (scope of application) are expected to expand.

[0006] Therefore, an object of the present invention is to provide a means for efficiently producing a plant protein concentrate for use in foods, beverages, etc. Another object of the present invention is to increase the utility value of plant proteins by enabling the production of plant protein concentrates with improved physical properties (particularly solubility), thereby contributing to improving the quality of existing uses and creating new uses. [Means for solving the problem]

[0007] In the course of conducting research in light of the above-mentioned problems, the present inventors have focused on the possibility of improving yield and physical properties by enzymatic treatment, and have come up with the idea of ​​incorporating a step of enzymatic treatment with protein deamidase, specifically, treatment of a plant protein raw material with protein deamidase, into the process for producing a plant protein concentrate. Protein deamidase is used in various applications, such as food processing (see, for example, Patent Document 1).

[0008] The effects of treatment with protein deamidase were examined on four types of plant protein raw materials (peas, chickpeas, soybeans, almonds, oats, and quinoa), and an improvement in protein yield (increased yield) was observed, along with unexpected findings regarding the relationship between treatment conditions and effects (improved yield, etc.). Furthermore, evaluation of the physical properties of the resulting plant protein concentrate surprisingly revealed significant improvements in solubility, etc. In other words, it became clear that treatment with protein deamidase not only had a favorable effect on yield, but also on the physical properties of the resulting plant protein concentrate. The following invention is based primarily on the above results. [1] A method for producing a plant protein concentrate, comprising treating a plant protein raw material with a protein deamidating enzyme. [2] The manufacturing method according to [1], wherein the plant protein raw material is one or more beans, grains, or nuts selected from the group consisting of peas, chickpeas, soybeans, fava beans, lentils, oats, rye, barley, corn, amaranth, sesame, almonds, peanuts, cashew nuts, hazelnuts, pecan nuts, macadamia nuts, pistachios, walnuts, Brazil nuts, coconuts, chestnuts, pine nuts, hemp seeds, quinoa, and chia seeds. [3] The method according to [1] or [2], wherein the protein deamidase is protein glutaminase. [4] The method according to any one of [1] to [3], wherein the protein deamidase is an enzyme derived from a microorganism of the genus Chryseobacterium. [5] The method of producing according to [4], wherein the Chryseobacterium microorganism is Chryseobacterium proteolyticum. [6] The method according to any one of [1] to [5], wherein the amount of protein deamidase used is 0.01 U to 500 U per 1 g of the plant protein raw material. [7] The method according to any one of [1] to [6], wherein the concentration of the plant protein raw material during the treatment with protein deamidase is 10 to 35% (w / w). [8] The production method according to any one of [1] to [7], further comprising a step of removing components other than proteins after the treatment with protein deamidase. [9] The production method described in [8], wherein the step of removing components other than proteins further includes the following steps (1) to (3): (1) a step of adjusting the pH of the enzyme reaction solution after treatment with protein deamidating enzyme, performing an alkali treatment, and separating soluble components; (2) recovering proteins from the separated soluble components by isoelectric precipitation; and (3) A step of neutralizing the recovered protein.

[10] The method according to [9], wherein the alkali treatment is carried out under conditions of pH 8 to 12, and the isoelectric precipitation is carried out under conditions of pH 3 to 6.

[11] The method according to [9], wherein the alkali treatment is carried out under conditions of pH 9 to 12.

[12] The method according to [9], wherein the isoelectric precipitation is carried out under conditions of pH 4 to 6.

[13] The production method according to any one of [9] to

[12] , further comprising the following step (4): (4) A step of concentrating or drying after the neutralization treatment.

[14] A plant protein concentrate obtained by the production method described in any one of [1] to

[13] .

[15] A food or beverage containing a plant protein concentrate obtained by the manufacturing method described in any one of [1] to

[13] . DETAILED DESCRIPTION OF THE INVENTION

[0009] 1. Method for producing plant protein concentrate The present invention relates to a method for producing a vegetable protein concentrate. In the present invention, a vegetable protein raw material is treated with a protein deamidating enzyme to improve the protein yield. Meanwhile, as demonstrated by the examples described below, the present invention is also expected to improve the physical properties of the resulting vegetable protein concentrate.

[0010] A "plant protein concentrate" is a composition in which the protein content has been increased compared to the unprocessed state (i.e., the plant protein raw material) by extracting or concentrating the protein. Generally, a composition having a protein content of 29 to 89% (w / w) is called a protein concentrate. However, in the present invention, the term "protein concentrate" is broadly interpreted and also includes compositions having a protein content of 90% (w / w) or more, i.e., those generally referred to as protein isolates. In other words, in this application, the term "protein concentrate" is used to encompass protein isolates having a higher protein content.

[0011] Generally, plant protein concentrates such as soy protein (soy protein powder, etc.) and pea protein (pea protein powder, etc.) are produced by a method combining alkali treatment and isoelectric precipitation (see, for example, Non-Patent Documents 1 and 2 listed above), a method combining alkali treatment and membrane separation, or the like. As described above, protein isolates are produced from protein concentrates through processes such as membrane concentration. While this may vary depending on the type / origin and protein content of the plant protein raw material used, the production process (particularly whether or not membrane concentration is used), and production conditions, the production method of the present invention can produce plant protein concentrates with a protein content in the range of 29% to 99%.

[0012] The production method of the present invention is characterized by "including a step of treating a plant protein material with protein deamidating enzyme." In the present invention, the plant protein material refers to a plant material containing protein. The plant protein material to be subjected to the enzyme treatment is not particularly limited, and various materials classified as beans, grains, or nuts and seeds can be used. Specific examples of plant protein materials include peas, chickpeas, soybeans, fava beans, lentils, oats, rye, barley, corn, amaranth, sesame, almonds, peanuts, cashew nuts, hazelnuts, pecan nuts, macadamia nuts, pistachios, walnuts, Brazil nuts, coconuts, chestnuts, pine nuts, hemp seeds, quinoa, and chia seeds. Furthermore, processed materials (e.g., starch extraction, defatted, etc.) from the above materials or residues from the processing can also be used. Two or more types of plant protein materials can also be used in combination.

[0013] To ensure that the enzymatic reaction proceeds efficiently, a disrupted or pulverized (powdered) plant protein raw material is usually subjected to the enzymatic treatment. Specifically, a protein deamidating enzyme is added to a suspension or solution of the disrupted or pulverized plant protein raw material, and the reaction is carried out.

[0014] In the present invention, protein deamidase refers to an enzyme that acts directly on the amide groups in the side chains of amino acids that constitute proteins, deamidating them and liberating ammonia, without cleaving peptide bonds in proteins or crosslinking proteins. Specific examples of protein deamidase include protein glutaminase, which acts directly on the amide groups in the side chains of glutamine residues contained in proteins, liberating ammonia and converting the glutamine residues to glutamic acid residues, and protein asparaginase, which acts directly on the amide groups in the side chains of asparagine residues contained in proteins, liberating ammonia and converting the asparagine residues to aspartic acid residues. In the present invention, either protein glutaminase or protein asparaginase may be used as the protein deamidase, or a combination of these may be used. A preferred example of the protein deamidase used in the present invention is protein glutaminase.

[0015] The protein deamidase used in the present invention is not particularly limited in type or origin. Examples of protein deamidase include protein deamidases derived from the genera Chryseobacterium, Flavobacterium, Empedobacter, Sphingobacterium, Aureobacterium, or Myroides, as disclosed in the above-mentioned Patent Document 1 (JP 2000-50887 A), JP 2001-218590 A, WO 2006 / 075772, etc., and commercially available protein glutaminases derived from the genus Chryseobacterium. Protein deamidases derived from the genus Chryseobacterium are preferred, and protein deamidase derived from Chryseobacterium proteolyticum is more preferred. Protein glutaminase derived from Chryseobacterium proteolyticum is commercially available, for example, as Protein-glutaminase "Amano" 500 manufactured by Amano Enzyme Inc., and this commercially available product can be used.

[0016] Protein deamidase can be prepared from a culture medium of a microorganism that produces protein deamidase. The microorganism used for preparing protein deamidase is not particularly limited, and microorganisms that produce the enzyme, such as those belonging to the genus Chryseobacterium, Flavobacterium, Empedobacter, Sphingobacterium, Aureobacterium, or Myroides, can be used. Alternatively, a microorganism into which a protein deamidase gene has been introduced by genetic engineering can be used. A specific example of a microorganism suitable for preparing protein deamidase is Chryseobacterium sp. No. 9670, which belongs to the genus Chryseobacterium.

[0017] For example, protein deamidase can be obtained from the culture medium or bacterial cells of the above-mentioned microorganisms. That is, if it is a secretory protein, it can be recovered from the culture medium, and if not, it can be recovered from the bacterial cells. Protein deamidase can be prepared from the culture medium by known protein separation and purification methods (centrifugation, UF concentration, salting out, various types of chromatography using ion exchange resins, etc., etc.). For example, the culture medium can be centrifuged to remove the bacterial cells, and then the target enzyme can be obtained by combining salting out, chromatography, etc. When the enzyme is recovered from the bacterial cells, for example, the bacterial cells can be disrupted by pressure treatment, ultrasonic treatment, etc., and then separated and purified in the same manner as above, to obtain the target enzyme. Note that the bacterial cells may be recovered from the culture medium in advance by filtration, centrifugation, etc., and then the above series of steps (disruption, separation, and purification of the bacterial cells) may be carried out. The enzyme may be powdered by a drying method such as freeze-drying or vacuum drying, and in this case, an appropriate excipient or drying aid may be used.

[0018] In the present application, the activity of protein deamidase is measured by the following method. (1) 0.1 ml of an aqueous solution containing protein deamidase is added to 1 ml of 0.2 M phosphate buffer (pH 6.5) containing 30 mM ZX-Gly, and the mixture is incubated at 37°C for 10 minutes. The reaction is then stopped by adding 1 ml of 0.4 M TCA solution. A blank is prepared by adding 0.1 ml of an aqueous solution containing protein deamidase to 1 ml of 0.2 M phosphate buffer (pH 6.5) containing 30 mM ZX-Gly and 1 ml of 0.4 M TCA solution, and incubating the mixture at 37°C for 10 minutes. In "ZX-Gly," Z represents benzyloxycarbonyl, X represents an L-glutamine residue or an L-asparagine residue, and Gly represents a glycine residue. That is, when X is an L-glutamine residue, "ZX-Gly" is benzyloxycarbonyl-L-glutaminylglycine, and when X is an L-asparagine residue, "ZX-Gly" is benzyloxycarbonyl-L-asparaginylglycine. When the protein deamidase to be measured is protein glutaminase, "ZX-Gly" in which X is an L-glutamine residue is used, and when the protein deamidase to be measured is protein asparaginase, "ZX-Gly" in which X is an L-asparagine residue is used. (2) The amount of ammonia produced by the reaction in the solution obtained in (1) is measured. The amount of ammonia can be measured, for example, using an Ammonia Test Wako (Wako Pure Chemical Industries, Ltd.). The ammonia concentration in the reaction solution is determined from a calibration curve showing the relationship between ammonia concentration and absorbance (630 nm) prepared using an ammonia standard solution (ammonium chloride). (3) Protein deamidase activity is calculated using the following formula, where 1 unit is the amount of enzyme that produces 1 μmol of ammonia per minute. Enzyme activity (U / mL) = ammonia concentration in reaction solution (mg / L) × (1 / 17.03) × (volume of reaction solution / volume of enzyme solution) × (1 / 10) × Df (In the formula, the volume of the reaction solution is 2.1, the volume of the enzyme solution is 0.1, Df is the dilution factor of the enzyme solution, and 17.03 is the molecular weight of ammonia.)

[0019] The conditions for the treatment with protein deamidase are not particularly limited as long as they are effective in achieving the effects of the present invention, i.e., in improving the yield and / or the physical properties of the resulting vegetable protein concentrate. Optimal reaction conditions may be set depending on the enzyme used by adjusting the vegetable protein raw material concentration, reaction temperature, reaction pH, reaction time, amount of enzyme added (enzyme concentration), etc. through preliminary experiments.

[0020] Although not limited to this example, the concentration of the plant protein raw material in the non-treatment liquid (the plant protein raw material solution to be treated with protein deamidating enzyme) is, for example, 5 to 40% (w / w), preferably 10 to 35% (w / w), and more preferably 15 to 30% (w / w). Increasing the plant protein raw material concentration is effective in improving treatment efficiency and thereby reducing production costs. On the other hand, if the plant protein raw material concentration is too high, the solubility of the protein decreases, and there is a possibility that the treatment will not be sufficient. The reaction temperature may be set, for example, within the range of 2°C to 70°C, preferably within the range of 5°C to 60°C, and more preferably within the range of 15°C to 50°C. The reaction pH may be set, for example, within the range of pH 3 to 10, preferably within the range of pH 4 to 9, and more preferably within the range of pH 5 to 9. Similarly, the reaction time may be set, for example, within the range of 10 minutes to 7 days, preferably within the range of 30 minutes to 3 days, and more preferably within the range of 1 hour to 1 day. The amount of enzyme added may be set, for example, within the range of 0.01 (U / g plant protein raw material) to 500 (U / g plant protein raw material), preferably 0.05 (U / g plant protein raw material) to 300 (U / g plant protein raw material), more preferably 0.1 (U / g plant protein raw material) to 200 (U / g plant protein raw material), even more preferably 0.25 (U / g plant protein raw material) to 100 (U / g plant protein raw material), and even more preferably 0.25 to 25 (U / g plant protein raw material). Here, "U / g plant protein raw material" refers to the number of units per gram of plant protein raw material on which protein deamidase will act.

[0021] After treatment with protein deamidase, a vegetable protein concentrate can be obtained by removing components other than protein. Removal of components other than protein can be achieved, for example, by extracting and concentrating the protein (removing unnecessary components) using a conventional method (see, for example, Non-Patent Documents 1 and 2 listed above). For example, vegetable protein can be extracted and concentrated by a method that combines alkali treatment (alkaline extraction method) and isoelectric precipitation. When this method is applied, the following steps (1) to (3) are typically carried out. (1) After the treatment with protein deamidating enzyme, the pH of the enzyme reaction solution is adjusted to perform alkali treatment, and soluble components are separated. (2) recovering proteins from the separated soluble components by isoelectric precipitation; (3) Neutralizing the recovered protein

[0022] Step (1) is a process of separating proteins from unnecessary components (dietary fiber, starch, etc.) by alkali treatment (alkali extraction), and proteins are separated as soluble components. The solution after enzyme treatment (enzyme reaction solution) is adjusted to a pH of, for example, 8 to 12, preferably 9 to 11, and treated, for example, at 10°C to 50°C for a predetermined time (for example, 5 minutes to 24 hours, preferably 10 minutes to 2 hours). NaOH, sodium carbonate, etc. can be used to adjust the pH. Increasing the pH is effective in increasing the protein yield in alkali treatment. Therefore, to increase the protein yield, the pH of the enzyme reaction solution is preferably adjusted to a pH of 9 to 12, more preferably 9.5 to 11.5, and even more preferably 10 to 11.

[0023] After the alkali treatment, the soluble components (containing proteins) are separated from the insoluble components by centrifugation or the like. In the case of centrifugation, the soluble components are collected as the supernatant.

[0024] Proteins are recovered from the separated soluble components by isoelectric precipitation (step (2)). For example, when the soluble components are recovered as a supernatant after centrifugation, the pH of the supernatant (which may be diluted or concentrated prior to pH adjustment) is adjusted to about 3 to 6 to precipitate the proteins, and the precipitate is then recovered by centrifugation. The pH may be set to an optimum condition taking into consideration the isoelectric point of the plant protein raw material used, for example, a pH of 3 to 6. While it is preferable to adopt a pH near the isoelectric point in terms of the principles of isoelectric precipitation, in order to reduce the amount of pH adjuster added, it is best to adjust the pH to a range of preferably 4 to 6, more preferably 4.5 to 6, and even more preferably 4.5 to 5.

[0025] After step (2), a neutralization treatment is carried out (step (3)). Typically, the precipitate recovered in step (2) is suspended in an appropriate solvent (e.g., water), and then an alkali such as NaOH or sodium carbonate is added to neutralize the suspension. After the neutralization treatment, if necessary, treatments such as concentration (membrane concentration, vacuum evaporation, etc.) and drying (spray drying, freeze drying, etc.) are carried out to obtain a plant protein concentrate. The form of the plant protein concentrate (e.g., powder, granules, liquid) is not particularly limited.

[0026] As described above, steps (1) to (3) are typically performed, but it is also possible to omit step (1) (i.e., without performing the alkaline treatment) and perform protein extraction and concentration by isoelectric precipitation in step (2) (subjecting the solution after enzyme treatment to isoelectric precipitation) followed by step (3). This embodiment can be adopted, for example, when a relatively low protein content in the plant protein concentrate is acceptable, thereby simplifying the production process.

[0027] 2. Uses of Plant Protein Concentrate The plant protein concentrate obtained by the production method of the present invention has commercial value in itself. It is also useful as a material or ingredient for increasing the protein content of various foods, beverages, etc. Therefore, the present application also provides foods or beverages containing the plant protein concentrate obtained by the production method of the present invention. The foods and beverages in this context are not particularly limited. Examples of foods and beverages include processed seafood products (chikuwa, kamaboko, hanpen, dried squid, dried fish, salted fish, fish sausage, tsukudani, canned foods, etc.), processed meat products (ham, bacon, sausage, jerky, corned beef, formed meat, etc.), processed vegetables (canned and bottled vegetables, processed tomatoes, processed mushrooms, pickled vegetables, dried vegetables, tsukudani, etc.), noodles and breads (various types of noodles, bread, sweet rolls, etc.), processed grain products (cereals, oatmeal, muesli, processed rice products, wheat gluten, barley tea, etc.), dairy products (milk, processed milk, dairy drinks, concentrated milk, milk powder, condensed milk, fermented milk, lactic acid bacteria drinks, butter, cheese, ice cream, etc.), processed fruit products (canned and bottled fruit, jams, marmalades, dried fruits, etc.), sweets and desserts (biscuits, baked goods, rice crackers, fried sweets, fresh Japanese sweets, fresh Western sweets, semi-fresh sweets, dried Japanese sweets, candies, chocolates, chewing gum, snacks, frozen desserts, etc.), beverages (soft drinks, carbonated drinks, fruit juice drinks, coffee drinks, vegetable juice drinks, tea drinks, non-alcoholic drinks, alcoholic drinks, etc.), seasonings (sauces, soups, dressings, sauces, etc.), soups, roux (curry roux, stew roux, etc.), nutritional supplements and beverages (protein powders, protein drinks, supplements, energy drinks, etc.), pet food, nutritional supplements for pets.

[0028] The plant protein concentrate is added or mixed with other raw materials or intermediate products during the production process of the food or beverage to be blended therein. Preferably, the plant protein concentrate is added or mixed at the final stage of the production process, i.e., after the other raw materials have been mixed and processed (the stage at which the product is in the form / shape of the product). However, subsequent sterilization treatments and the addition of seasonings, preservatives, flavorings, antioxidants, etc. for the purposes of adjusting taste and maintaining quality may also be performed. On the other hand, mixing the plant protein concentrate with a food or beverage after the production process has been completed (i.e., in the form of a final product rather than an intermediate product) is also a preferred embodiment. In this embodiment, the present invention can be applied without changing the food or beverage production process. [Example]

[0029] <Production of plant protein concentrate using protein deamidating enzyme> The effectiveness of protein deamidating enzymes for improving the protein yield of plant protein concentrates was investigated. Protein glutaminase (hereinafter abbreviated as "PG") was used as a representative example of protein deamidating enzymes.

[0030] 1. Consideration of PG dosage (1) Method Suspensions were prepared by suspending 30 g of powdered plant materials (chickpea, pea, or almond) or 15 g of soybean powder in 100 mL of water, and by suspending 30 g of oat or quinoa powder in 170 mL of water. Protein glutaminase (Protein-glutaminase "Amano" 500, Amano Enzymes Inc.; 500 U / g, protein content 10% by weight or less) was added to each suspension to the activity shown in Table 1, and the mixture was stirred at 50°C and 200 rpm for 2 hours to allow for the enzymatic reaction. When using oat and quinoa powders, 15 mg of α-amylase (KLEISTASE SD80, Amano Enzymes Inc.) was added along with the protein glutaminase to suppress the increase in viscosity due to the starch contained in these powders. The pH was then adjusted to 10 with 1N NaOH, followed by alkali treatment at 50°C and 200 rpm for 30 minutes, followed by centrifugation to recover the supernatant. The pH of the recovered supernatant was adjusted to a weak acidic value with 1N HCl, and the precipitate was recovered by centrifugation. The pH adjustment with 1N HCl was adjusted to 4.5 when oat and quinoa powders were used, and to 4.0 when other powders were used. The precipitate was suspended in water, neutralized with 1N NaOH, and lyophilized to obtain a plant protein concentrate. The protein yield was calculated as the ratio of the weight of the resulting plant protein concentrate to the weight of the plant raw material powder used, and evaluated as the ratio of the protein yield to that without PG treatment. Here, "without PG treatment" refers to the protein yield obtained by the same procedure as above, except without PG treatment.

[0031] (2) Results (Table 1) It was confirmed that PG treatment improves protein yield. It was also confirmed that increasing the PG activity used improves yield. For peas, the same method as above was used, but with the addition of 750 U of protein glutaminase. The protein yield was 124% of that without PG treatment, and it was confirmed that the yield also improved when the amount of protein glutaminase added was further increased. [Table 1]

[0032] 2. Examination of PG treatment pH (1) Method Thirty grams of pea powder was suspended in 100 mL of water and adjusted to the appropriate pH with 1N NaOH or 1N HCl. 150 U of protein glutaminase (Protein-glutaminase "Amano" 500, Amano Enzyme Inc.; 500 U / g, protein content 10% by weight or less) was added and the mixture was stirred at 50°C and 200 rpm for 2 hours for enzymatic reaction. The pH was then adjusted to 11 with 1N NaOH and alkali-treated with stirring at 50°C and 200 rpm for 30 minutes. The supernatant was then centrifuged and the supernatant was recovered. The pH of the recovered supernatant was adjusted to 4.0 with 1N HCl and the precipitate was collected by centrifugation. The precipitate was suspended in water, neutralized with 1N NaOH, and lyophilized to obtain a plant protein concentrate. The protein yield was calculated as the ratio of the weight of the resulting plant protein concentrate to the weight of the plant raw material powder used, and evaluated as the protein yield relative to that without PG treatment. Here, "without PG treatment" refers to the protein yield when the same procedure as above was performed except that PG treatment was not performed.

[0033] (2) Results (Table 2) It was confirmed that PG treatment at pH 7 to 9 improved protein yield. [Table 2]

[0034] 3. Consideration of alkaline treatment pH (1) Method 30 g of powdered plant material (chickpea, pea) or 15 g of soybean powder was suspended in 100 mL of water, and 150 U of protein glutaminase (Protein-glutaminase "Amano" 500, Amano Enzyme Inc.; 500 U / g, protein content 10% by weight or less) (75 U for soybeans) was added. The enzyme reaction was then carried out by stirring at 50°C and 200 rpm for 2 hours. The pH was then adjusted to the appropriate level with 1N NaOH, followed by alkali treatment at 50°C and 200 rpm for 30 minutes while stirring. The supernatant was then centrifuged and the supernatant was recovered. The pH of the recovered supernatant was adjusted to 4.2 with 1N HCl, and the precipitate was recovered by centrifugation. The precipitate was suspended in water, neutralized with 1N NaOH, and lyophilized to obtain a plant protein concentrate. The protein yield was calculated as the ratio of the weight of the resulting plant protein concentrate to the weight of the plant material powder used, and evaluated as the protein yield relative to the yield without PG treatment. Here, "without PG treatment" refers to the protein yield when the same procedure as above was performed except that PG treatment was not performed.

[0035] (2) Results (Table 3) It was confirmed that PG treatment improves protein yield regardless of the pH of the alkaline treatment. Furthermore, it was confirmed that PG treatment can further improve yield, even when alkaline treatment is performed at pH 11, where proteins are thought to be completely solubilized. This suggests that PG treatment solubilizes proteins that cannot be solubilized by alkaline treatment. [Table 3]

[0036] 4. Examination of acid treatment pH (1) Method 30 g of chickpea powder or 15 g of soybean powder was suspended in 100 mL of water and 150 U of protein glutaminase (Protein-glutaminase "Amano" 500, Amano Enzyme Inc.; 500 U / g, protein content 10% by weight or less) (75 U for soybeans) was added. The enzyme reaction was then carried out by stirring at 50°C and 200 rpm for 2 hours. The pH was then adjusted to 10 with 1N NaOH and alkali-treated at 50°C and 200 rpm for 30 minutes, followed by centrifugation to recover the supernatant. The recovered supernatant was adjusted to the appropriate pH with 1N HCl and the precipitate was recovered by centrifugation. The precipitate was suspended in water, neutralized with 1N NaOH, and lyophilized to obtain a plant protein concentrate. The protein yield was calculated as the ratio of the weight of the resulting plant protein concentrate to the weight of the plant raw material powder used, and evaluated as the protein yield relative to that without PG treatment. Here, "without PG treatment" refers to the protein yield when the same procedure as above was performed except that PG treatment was not performed.

[0037] (2) Results (Table 4) It was confirmed that PG treatment improves protein yield regardless of the pH of the acid treatment (isoelectric precipitation treatment). PG treatment improves solubility in the acidic range, and it was expected that the yield would decrease unless the pH was set low. However, sufficient yield was obtained even at relatively high pH. It is noteworthy that the yield was not significantly different even at pH 4.5 or higher (especially pH 5) compared to pH 4.0 or lower. [Table 4]

[0038] 5. Evaluation of the physical properties of protein concentrates 30 g of pea powder was suspended in 100 mL of water, to which 150 U of protein glutaminase (Protein-glutaminase "Amano" 500, manufactured by Amano Enzyme Inc.; 500 U / g, protein content 10% by weight or less) was added, followed by 2 hours of stirring at 50°C and 200 rpm for an enzymatic reaction. The pH was then adjusted to 10 with 1N NaOH, and the mixture was treated with alkali at 50°C and 200 rpm for 30 minutes while stirring. The supernatant was then centrifuged and the supernatant was recovered. The pH of the recovered supernatant was adjusted to 4.2 with 1N HCl, and the precipitate was recovered by centrifugation. The precipitate was suspended in water, neutralized with 1N NaOH, and freeze-dried to obtain a pea protein concentrate.

[0039] The obtained pea protein concentrate was suspended in water to prepare a 10% (w / w) suspension at pH 7.0, and the texture was evaluated. The PG-treated pea protein concentrate had a smooth texture, whereas the untreated pea protein concentrate had a rough texture.

[0040] The resulting pea protein concentrate was suspended in water to prepare a 10% (w / w) suspension at pH 5.5, and the solubility was evaluated. The results showed that the PG-treated pea protein concentrate had improved solubility.

[0041] These results confirm that PG treatment not only improves protein yield, but also alters the physical properties of the resulting protein concentrate, improving its solubility. These physical properties are desirable for food and beverage applications, leading to improved product quality and expanded applications. [Industrial Applicability]

[0042] The present invention provides an efficient method for producing plant protein concentrates. Plant protein concentrates are used in nutritional supplements and beverages, as well as fortified foods and beverages. While some protein concentrates / isolates used in foods and beverages are derived from animal proteins (whey protein isolate, casey protein, etc.), growing health consciousness and other factors are expected to lead to further growth in demand for plant protein concentrates. The present invention meets these market needs and has great utility value.

[0043] The present invention is not limited to the above-described embodiments and examples. Various modifications within the scope of the claims and within the scope that can be easily conceived by a person skilled in the art are also included in the present invention. The contents of papers, published patent applications, patent publications, and other publications explicitly stated in this specification are incorporated herein by reference in their entirety.

Claims

1. A method for producing plant protein concentrates, A step of treating plant protein raw materials with protein glutaminase under conditions of pH 8 to 9, and The process includes a step of removing non-protein components after treatment with protein glutaminase. The step of removing components other than the aforementioned protein is, (1) After treatment with protein glutaminase, the pH of the enzyme reaction solution is adjusted to 9.5-12 and subjected to alkaline treatment to separate the soluble components. (2) A step of recovering protein from the separated soluble components by isoelectric point precipitation, and (3) Step of neutralizing the recovered protein The manufacturing method, including the above.

2. The manufacturing method according to claim 1, wherein the plant protein raw material is one or more legumes, grains or seeds selected from the group consisting of peas, chickpeas, soybeans, broad beans, lentils, oats, rye, barley, corn, amaranth, sesame, almonds, peanuts, cashews, hazelnuts, pecans, macadamia nuts, pistachios, walnuts, Brazil nuts, coconuts, chestnuts, pine nuts, hemp seeds, quinoa, and chia seeds.

3. The method for producing protein glutaminase according to claim 1 or 2, wherein the protein glutaminase is an enzyme derived from a microorganism of the genus Chryseobacterium.

4. The method for producing a product according to claim 3, wherein the microorganism of the genus Chryseobacterium is Chryseobacterium proteoricum.

5. A manufacturing method according to any one of claims 1 to 4, wherein the amount of protein glutaminase used is 0.01 U to 500 U per gram of plant protein raw material.

6. The manufacturing method according to any one of claims 1 to 5, wherein the concentration of the plant protein raw material when treated with protein glutaminase is 10 to 35% (w / w).

7. The manufacturing method according to any one of claims 1 to 6, wherein isoelectric point precipitation is performed under conditions of pH 4 to 6.

8. A manufacturing method according to any one of claims 1 to 7, further comprising the following step (4): (4) A step of concentrating or drying after neutralization treatment.