Method for producing processed oat protein-containing liquid composition

Abstract

The purpose of the present invention is to provide a processing technique for improving the foamability of a liquid composition containing oat protein. The foamability of a liquid composition containing oat protein can be improved according to a method for producing a processed liquid composition containing oat protein, said method comprising: an enzyme treatment step for obtaining an enzymatically treated liquid composition by causing a protein deamidase to act on the liquid composition containing oat protein at a prescribed pH; and a pH reduction step for reducing the pH of the enzyme-treated liquid composition to obtain a processed liquid composition containing oat protein.

Description

Technical Field

[0001] The present invention relates to a processing technology for improving the foaming property of a liquid composition containing oat protein. Background Art

[0002] Beverages rich in nutritional components such as protein can easily provide nutrients, and have thus been widely popular among people in the past.

[0003] Against the backdrop of the recent increase in vegetarians, allergy issues, and religious reasons, etc., beverages made from plant-based proteins such as soybeans, oats, and almonds, which are rich in plant-based proteins, have been widely popularized as alternatives to animal milk represented by cow's milk.

[0004] On the other hand, when replacing milk protein raw materials with plant-based protein raw materials, due to differences in the types of proteins, etc., direct replacement is not possible in many cases. Therefore, various technologies related to processing for modifying plant-based protein raw materials have been proposed.

[0005] For example, Patent Document 1 describes that by treating an oat suspension with α α-amylase and β β-amylase, the problem of high viscosity peculiar to oat suspensions can be solved, and proteins and β β-glucan can be maintained.

[0006] Patent Document 2 describes that by treating plant-based milk with protein deamidase, the dispersion stability and solubility can be improved.

[0007] Prior Art Documents Patent Documents Patent Document 1: US Patent No. 6451369 Specification Patent Document 2: International Publication No. 2022 / 071418 Summary of the Invention

[0008] Technical Problem to be Solved by the Invention Among plant-based protein materials, oats are known as a highly nutritious food ingredient. If oat milk is treated with protein deamidase, a modified effect of improving foaming property can be obtained. However, in view of the recent popularity of plant-based protein food and beverages, the improvement effect of foaming property achieved by simply treating with protein deamidase is not sufficient, and further improvement of this modified effect is desired.

[0009] Therefore, the object of the present invention is to provide a processing technology for improving the foaming property of a liquid composition containing oat protein.

[0010] Technical Solution for Solving the Technical Problem The present inventors conducted in-depth research and unexpectedly found that by subjecting a liquid composition containing oat protein to a pH reduction treatment after allowing a protein deamidase to act on it, the foaming property of the resulting processed liquid composition containing oat protein is improved as compared to the case where such treatment is not performed. The present invention was completed through further repeated research based on this finding.

[0011] That is, the present invention provides an invention in the manner disclosed below.

[0012] Item 1. A method for producing a processed liquid composition containing oat protein, comprising: an enzyme treatment step in which a protein deamidase is allowed to act on a liquid composition containing oat protein at a specified pH to obtain an enzyme-treated liquid composition; and a pH reduction step in which the pH of the enzyme-treated liquid composition is reduced to obtain a processed liquid composition containing oat protein.

[0013] Item 2. The production method according to Item 1, wherein the value obtained by subtracting the pH of the processed liquid composition containing oat protein at 25°C from the specified pH at 25°C is 0.2 to 4.

[0014] Item 3. The production method according to Item 1 or 2, wherein the specified pH at 25°C is 5.0 to 9.0.

[0015] Item 4. The production method according to any one of Items 1 to 3, wherein the pH of the processed liquid composition containing oat protein at 25°C is 4 to 7.5.

[0016] Item 5. The production method according to any one of Items 1 to 4, wherein the content of oat protein in the liquid composition containing oat protein is 0.01% by weight to 15% by weight.

[0017] Item 6. The production method according to any one of Items 1 to 5, wherein the liquid composition containing oat protein is oat milk.

[0018] Item 7. The production method according to any one of Items 1 to 6, wherein the protein deamidase is protein glutaminase.

[0019] Item 8. The production method according to any one of Items 1 to 7, wherein the amount of the protein deamidase used is 0.05 U or more per 1 g of oat protein contained in the liquid composition containing oat protein.

[0020] Item 9. A food or drink containing oat protein, which is produced using a processed liquid composition containing oat protein obtained by the production method according to any one of Items 1 to 8.

[0021] Item 10. The food or drink containing oat protein according to Item 9, wherein the processed liquid composition containing oat protein foams.

[0022] Advantages of the Invention According to the present invention, there is provided a processing technique for improving the foaming property of a liquid composition containing oat protein. Detailed Description of the Invention

[0023] 1. Method for manufacturing a processed liquid composition containing oat protein The production method of the processed liquid composition containing oat protein of the present invention is characterized by comprising: an enzyme treatment step of allowing a protein deamidase to act on a liquid composition containing oat protein at a specified pH to obtain an enzyme-treated liquid composition; and a pH reduction step of reducing the pH of the enzyme-treated liquid composition to obtain a processed liquid composition containing oat protein. The processed liquid composition containing oat protein obtained by the production method of the present invention is processed to improve its foaming property as compared with the case where the pH reduction step is not performed. Moreover, although the foam stability of the liquid composition containing oat protein is reduced by treatment with a protein deamidase, in a preferred embodiment of the processed liquid composition containing oat protein obtained by the production method of the present invention, it is processed to improve the foam stability as well as compared with the case where the pH reduction step is not performed. Hereinafter, the production method of the processed liquid composition containing oat protein of the present invention will be described in detail.

[0024] 1-1. Enzymatic treatment step In the enzyme treatment step, a protein deamidase is allowed to act on a liquid composition containing oat protein at a specified pH to obtain an enzyme-treated liquid composition. Specifically, an oat protein-enzyme mixture at the specified pH containing the liquid composition containing oat protein and the protein deamidase is prepared, and a treatment for allowing the enzyme reaction to proceed is performed to obtain an enzyme-treated liquid composition.

[0025] 1-1-1. Liquid composition containing oat protein The liquid composition containing oat protein is not particularly limited as long as it is a liquid in which oat protein is dissolved and / or dispersed in water. Specific examples of the liquid composition containing oat protein include: (i) a liquid obtained by dispersing a dry powder (preferably oat flour) of a material containing oat protein (preferably oat seeds, more preferably dehulled oats) in water and removing insolubles such as bran layers derived from oat seeds by any means such as centrifugal filtration, filtration, filter bags, sieves, etc. as needed; (ii) a liquid obtained by crushing and dispersing a material containing oat protein (preferably oat seeds, more preferably dehulled oats) in water and removing insolubles such as bran layers derived from oat seeds by any means such as centrifugal filtration, filtration, filter bags, sieves, etc. as needed; (iii) a liquid obtained by removing components other than oat protein from the liquid of (i) or (ii) above to increase the content of oat protein; (iv) a liquid obtained by dissolving and / or dispersing a dry powder prepared from any of the liquids of (i) to (iii) above in water, etc. In addition, the liquid composition containing oat protein is preferably a composition obtained by further treating any of the liquids of (i) to (iv) above with amylase. From the viewpoint of further improving the foaming property of the processed liquid composition containing oat protein, or from the viewpoint of further improving the foam stability on the basis of this viewpoint, preferred examples of the liquid composition containing oat protein include a liquid of (i) above, a liquid of (ii) above, or a liquid obtained by treating a liquid corresponding to these liquids of (iv) above with amylase, namely, oat milk.

[0026] The content of oat protein in the liquid composition containing oat protein used in the present invention is not particularly limited. For example, it may be 0.01% by weight to 15% by weight, 0.1% by weight to 7.5% by weight, or 0.25% by weight to 5% by weight. From the viewpoint of further improving the foaming property of the processed liquid composition containing oat protein, or from the viewpoint of further improving the foam stability on the basis of this viewpoint, it is preferably 0.5% by weight to 3% by weight or 0.75% by weight to 2.5% by weight, and more preferably 1% by weight to 2% by weight, 1.2% by weight to 1.8% by weight, or 1.4% by weight to 1.6% by weight.

[0027] When the liquid composition containing oat protein used in the present invention is the liquid of (i) above, the liquid of (ii) above, and the liquid of (iv) corresponding to these liquids, the content of oat protein in the liquid composition containing oat protein is not particularly limited either. For example, it may be 0.1% by weight to 50% by weight, 1% by weight to 40% by weight, or 2% by weight to 30% by weight. From the viewpoint of further improving the foaming property of the processed liquid composition containing oat protein, or from the viewpoint of further improving the foam stability on the basis of this viewpoint, preferably, it may be 2.5% by weight to 25% by weight, 5% by weight to 20% by weight, more preferably, it may be 8% by weight to 16% by weight, 9% by weight to 14% by weight, or 10% by weight to 12% by weight.

[0028] In the liquid composition containing oat protein, in addition to oat protein and water, as other components, any components may or may not be included. As other components, components derived from oat seeds, other food ingredients, and food additives can be cited. As food additives, thickeners, binders, seasonings, pH adjusters, buffers, colorants, flavors, etc. can be cited.

[0029] 1-1-2. Protein deamidase As the protein deamidase, as long as it shows the action of decomposing the amide group-containing side chain of the protein without accompanying the cleavage of peptide bonds and the cross-linking of proteins, its type, source, etc. are not particularly limited. Examples of protein deamidases are disclosed in JP-A-2000-50887, JP-A-2001-218590, and WO 2006 / 075772, and examples include protein deamidases derived from the genus Chryseobacterium, the genus Flavobacterium, the genus Empedobacter, the genus Sphingobacterium, the genus Aureobacterium, the genus Myroides, the genus Luteimicrobium, the genus Agromyces, the genus Microbacterium, and the genus Leifsonia. These protein deamidases can be used alone or in combination of multiple kinds.

[0030] Examples of protein deamidases include protein glutaminase and protein asparaginase. In a broad sense, protein arginine deiminase can also be cited. Among these protein deamidases, from the viewpoint of further improving the foaming property of a processed liquid composition containing oat protein, or from the viewpoint of further improving the foam stability on the basis of this viewpoint, protein glutaminase is preferably cited.

[0031] Among these protein deamidases, from the viewpoint of further improving the foaming property of a processed liquid composition containing oat protein, or from the viewpoint of further improving the foam stability on the basis of this viewpoint, a protein deamidase derived from the genus Chryseobacterium is more preferably cited, a protein glutaminase derived from the genus Chryseobacterium is further preferably cited, and a protein glutaminase derived from Chryseobacterium proteolyticum is even more preferably cited.

[0032] The protein deamidase can be prepared from the culture broth of the microorganism that is the source of the above protein deamidase. As a specific preparation method, a method of recovering the protein deamidase from the culture broth or cells of the above microorganism can be cited. For example, in the case of using a protein deamidase-secreting microorganism, the cells can be recovered from the culture broth by filtration, centrifugation, etc. as needed, and then the enzyme can be separated and / or purified. In addition, in the case of using a non-protein deamidase-secreting microorganism, the cells can be recovered from the culture broth as needed, and then the cells can be disrupted by pressure treatment, ultrasonic treatment, etc. to expose the enzyme, and then the enzyme can be separated and / or purified. As a method for separating and / or purifying the enzyme, known protein separation and / or purification methods can be used without particular limitation. For example, centrifugation, UF concentration, salting out, various chromatography methods using ion exchange resins, etc. can be cited. The separated and / or purified enzyme can be powdered by a drying method such as freeze drying or vacuum drying. In addition, the enzyme can also be powdered using an appropriate excipient and / or drying aid in this drying method. In addition, the separated and / or purified enzyme can also be added with an appropriate additive and filtered and sterilized to be made into a liquid state.

[0033] The amount of the protein deamidase used relative to the liquid composition containing oat protein is not particularly limited. However, as the amount used relative to each 1 g of oat protein contained in the liquid composition containing oat protein, for example, 0.05 U or more, 0.1 U or more, or 0.5 U or more can be mentioned. From the viewpoint of further improving the foaming property of the processed liquid composition containing oat protein, or from the viewpoint of further improving the foam stability on the basis of this viewpoint, preferably 1 U or more, 1.5 U or more, 2 U or more, or 2.5 U or more can be mentioned. More preferably, 3 U or more, 3.5 U or more, or 4 U or more can be mentioned. Further preferably, 4.5 U or more or 5 U or more can be mentioned. The upper limit is not particularly limited either, and for example, 500 U or less, 200 U or less, 100 U or less, 80 U or less, 60 U or less, 40 U or less, 30 U or less, 20 U or less, 12 U or less, 8 U or less, or 7 U or less can be mentioned.

[0034] In addition, regarding the activity of the protein deamidase, using benzyloxycarbonyl-L-glutaminylglycine (Z-Gln-Gly) as the substrate, the amount of the enzyme that liberates 1 μ mol of ammonia in 1 minute is defined as 1 unit (1 U).

[0035] 1-1-3. Reaction operation and treatment conditions The method for preparing the oat protein-enzyme mixture is not particularly limited. For example, there can be mentioned: a method for preparing an oat protein-enzyme mixture by preparing a liquid composition containing oat protein and mixing the liquid composition containing oat protein with the protein deamidase; and a method for preparing an oat protein-enzyme mixture while preparing a liquid composition containing oat protein by mixing the material of the liquid composition containing oat protein with the protein deamidase.

[0036] Regarding the specific range of the specified pH, as long as the effects of the present invention can be obtained, it is not particularly limited and can be appropriately set according to the optimal pH of the protein deamidase used. As a specific example of the specified pH (pH at 25°C), for example, 5.0 to 9.0, or 5.0 to 8.5 can be mentioned. From the viewpoint of further improving the foaming property of the processed liquid composition containing oat protein, or from the viewpoint of further improving the foam stability on the basis of this viewpoint, preferably 5.5 to 8.5, more preferably 6 to 8.4, further preferably 6.5 to 8.3, still further preferably 7 to 8.2, still further preferably 7.2 to 8.2, 7.4 to 8.2, 7.6 to 8.2, or 7.8 to 8.2 can be mentioned.

[0037] Regarding other treatment conditions (temperature, time, etc.) of the oat protein-enzyme mixture, there is no particular limitation as long as the effects of the present invention can be obtained.

[0038] As the treatment temperature, it can be appropriately set according to the optimal temperature of the protein deamidase used. Specific examples of the treatment temperature include, for example, 20°C to 70°C, preferably 40°C to 68°C, more preferably 50°C to 66°C, further preferably 55°C to 64°C, and even more preferably 58°C to 62°C. Regarding the treatment time, it can be appropriately set according to the scale of the oat protein-enzyme mixture and the treatment temperature, etc. Specific examples of the treatment time include, for example, 0.5 hours to 4 hours, preferably 0.6 hours to 2 hours, more preferably 0.7 hours to 1.5 hours, or 0.8 hours to 1.2 hours.

[0039] These treatment conditions can be determined by preliminary experiments according to the required foaming property, or the degree of foaming property and foam stability of the processed liquid composition containing oat protein.

[0040] 1-2. pH reduction step In the pH reduction step, the pH of the enzyme-treated liquid composition obtained through the above enzyme treatment step is reduced to obtain a processed liquid composition containing oat protein.

[0041] As methods for reducing the pH, there are methods of adding a pH regulator, methods of mixing with acidic food and beverages, and methods of adding acidic food additives other than pH regulators. As methods for reducing the pH, any one of these methods can be used alone, or two or more methods can be used in combination. As pH regulators, there are inorganic acids such as hydrochloric acid and sulfuric acid; organic acids such as lactic acid and citric acid; salts of strong acids and weak bases, etc. In addition, in order to finely adjust the pH, inorganic bases such as hydroxides of alkali metals (sodium hydroxide, potassium hydroxide, etc.) and organic bases such as triethanolamine and triisopropanolamine can be used in combination. Among these pH regulators, inorganic acids are preferably used. As acidic food and beverages, there are oat yogurt, coffee, fruit beverages, etc. As these acidic food and beverages, there are non-heated and non-cooled food and beverages, or food and beverages that are cooled (for example, it can be cited as exceeding 5°C and lower than normal temperature or 5°C or lower). As acidic food additives other than pH regulators, there are acidic amino acids, acidic vitamins, etc. These pH regulators, acidic food and beverages, and food additives can be used alone one by one, or multiple of them can be used in combination.

[0042] Regarding the degree of pH reduction, it may be appropriately set according to the degree of foaming property required for the processed liquid composition containing oat protein, or the degree of foaming property and foam stability. However, the value obtained by subtracting the pH of the processed liquid composition containing oat protein at 25°C from the specified pH at 25°C may be, for example, in the range of 0.2 to 4. From the viewpoint of further improving the foaming property of the processed liquid composition containing oat protein, or from the viewpoint of further improving the foam stability on the basis of this viewpoint, preferably, it may be 1 to 4, more preferably 1.5 to 4, further preferably 2 to 4, still further preferably 2.4 to 4, 2.6 to 3.5, or 2.8 to 3.2.

[0043] Regarding the pH of the processed liquid composition containing oat protein obtained in the pH reduction step at 25°C, specifically, for example, it may be 4 to 7.8. From the viewpoint of further improving the foaming property of the processed liquid composition containing oat protein, or from the viewpoint of further improving the foam stability on the basis of this viewpoint, preferably, it may be 4 to 7.5, or 4 to 7, more preferably 4 to 6.6, further preferably 4 to 6.1, still further preferably 4 to 5.6. In addition, generally, the foaming property and foam stability deteriorate significantly at low pH. However, the foaming property, or the foaming property and foam stability of the processed liquid composition containing oat protein obtained by the present invention are excellent. Therefore, even at low pH, excellent foaming property, or excellent foaming property and foam stability can be obtained. From such a viewpoint, as a preferred example of the pH of the processed liquid composition containing oat protein at 25°C, it may be 4 to 6.6, more preferably 4 to 6.1, further preferably 4 to 5.6, still further preferably 4 to 5.4, 4.5 to 5.4, 4.5 to 5.2, 4.8 to 5.2, or 4.8 to 5.

[0044] 1-3. Other steps The method for manufacturing the processed liquid composition containing oat protein of the present invention may or may not include other steps in addition to the above-mentioned enzyme treatment step and pH reduction step. As other steps, there may be mentioned a preparation step of the liquid composition containing oat protein, an enzyme inactivation step, an enzyme treatment step based on an enzyme other than protein deamidase, a cooling step, a filtration step, a drying step, and the like. These other steps may be carried out individually or two or more steps may be carried out in combination.

[0045] The step of preparing the liquid composition containing oat protein can be performed by any method capable of preparing the liquid composition containing oat protein. For example, the following methods can be mentioned: (I) a method of preparing by dispersing a dry powder (preferably oat flour) of a material containing oat protein (preferably oat seeds, more preferably dehulled oats) in water, and removing insolubles such as bran layers derived from oat seeds by any means such as centrifugal filtration, filtration, filter bags, sieves, etc. as needed; (II) a method of preparing by crushing and dispersing a material containing oat protein (preferably oat seeds, more preferably dehulled oats) in water, and removing insolubles such as bran layers derived from oat seeds by any means such as centrifugal filtration, filtration, filter bags, sieves, etc. as needed; (III) a method of preparing by increasing the content of oat protein by removing components other than oat protein from the liquid obtained by the above method (I) or (II); (IV) a method of preparing by drying a liquid obtained by any of the above methods (I) to (III), and dissolving and / or dispersing the obtained dry powder in water, etc.

[0046] When the oat protein-containing liquid composition is prepared as an amylase-treated composition, the liquid obtained by any one of the methods (I) to (IV) above is treated with amylase. Examples of amylase include α -Amylase, β -amylase. These amylases may be used alone or in combination. In the present invention, from the viewpoint of further improving the foaming property of the processed oat protein-containing liquid composition, or in addition to this viewpoint, from the viewpoint of improving the foam stability, the oat protein-containing liquid composition is preferably prepared with α -Amylase and β - Amylase-treated composition.

[0047] As α -Amylase is not particularly limited, and examples thereof include those derived from Aspergillus (e.g., Aspergillus oryzae, Aspergillus niger, etc.), Bacillus (e.g., Bacillus amyloliquefaciens, Bacillus subtilis, Bacillus licheniformis, etc.) α -Amylase, preferably derived from Bacillus α - amylase, more preferably derived from Bacillus amyloliquefaciens α -Amylase.

[0048] about αThe amount of α - amylase used is, for example, 0.01 U to 1000 U, preferably 0.1 U to 100 U, more preferably 0.5 U to 50 U, further preferably 1 U to 30 U, still further preferably 5 U to 20 U, or 8 U to 15 U, relative to every 1 g of starch in the liquid composition containing oat protein.

[0049] Regarding α The activity of α - amylase is defined such that, using potato starch as the substrate, the amount of enzyme that reduces the color development by iodine by 10% within 1 minute is set as 1 unit (1 U).

[0050] As β α - amylase is not particularly limited. For example, it may include α - amylase derived from plants (such as wheat and soybean) and α - amylase derived from the genus Bacillus. β α - amylase derived from the genus Bacillus is preferably used, β and more preferably α - amylase derived from the species Bacillus flexus. β α - amylase.

[0051] Regarding β The amount of α - amylase used is, for example, 0.0001 U to 9 U, preferably 0.001 U to 0.9 U, more preferably 0.01 U to 0.4 U, further preferably 0.03 U to 0.2 U, still further preferably 0.06 U to 0.12 U, relative to every 1 g of starch in the liquid composition containing oat protein.

[0052] Regarding β The activity of α - amylase is defined such that, using potato starch as the substrate, the amount of enzyme that increases the reducing power equivalent to 1 mg of glucose produced within 1 minute is taken as 1 unit (1 U).

[0053] Regarding the conditions for amylase treatment (treatment pH, treatment temperature, treatment time), they can be appropriately set according to the optimal pH and temperature of the enzyme used, the scale of the liquid composition containing oat protein, and the required degree of solubility, etc.

[0054] For example, regarding the treatment pH, the pH (25 °C) of the liquid composition containing oat protein before amylase treatment is, for example, 5.5 to 7.5. From the viewpoint of further improving the foaming property, it is preferably 6.2 to 7.2, more preferably 6.5 to 7.2, further preferably 6.8 to 7.2, particularly preferably 7.0. From the viewpoint of further improving the foam stability, it is preferably 6.2 to 7.2, more preferably 6.3 to 6.7, particularly preferably 6.5.

[0055] As the treatment temperature, for example, 50°C to 65°C can be cited, preferably 50°C to 60°C, and more preferably 52°C to 56°C can be cited. As the treatment time, for example, 0.5 hour to 2 hours can be cited.

[0056] In the enzyme inactivation step, the temperature conditions and / or pH conditions for inactivating the enzyme used can be appropriately selected in consideration of the temperature characteristics and / or pH characteristics of the processed liquid composition containing oat protein, and preferably the temperature conditions can be selected. As specific temperature conditions, for example, 85°C to 120°C can be cited, preferably 90°C to 100°C, and more preferably 93°C to 98°C can be cited. As the treatment time, for example, 1 minute to 30 minutes, or 1 minute to 10 minutes can be cited, and preferably 3 minutes to 8 minutes can be cited.

[0057] 2. Food and drink containing oat protein The processed liquid composition containing oat protein obtained by the above manufacturing method can be used as a material for food and beverages (food and beverages containing oat protein). The processed liquid composition containing oat protein has excellent foaming properties, or excellent foaming properties and foam stability. Therefore, as a specific form of food and beverages containing oat protein, it can be used for food and beverages in which the processed liquid composition containing oat protein is in a foamed state, or food and beverages that are foamed with the processed liquid composition containing oat protein at the time of use and then served for consumption.

[0058] As specific examples of food and beverages containing oat protein, oat milk, oat cream, oat yogurt, and food and beverages containing them can be cited. These food and beverages themselves can be mixed with other beverages such as tea, coffee, and fruit drinks, and can also be mixed with these other beverages at the time of use and then served for consumption. In addition, even if the pH of the processed liquid composition containing oat protein is low, it exhibits excellent foaming properties, or excellent foaming properties and foam stability. Therefore, as a preferred form of these food and beverages, the following can be cited: substances prepared as oat yogurt; substances obtained by mixing itself with beverages having a low pH such as coffee and fruit drinks; substances that are mixed with the beverage having a low pH at the time of use and then served for consumption. There is no particular limitation on the temperature of the food and beverage. Any of the heated (for example, above room temperature and below 50°C or 50°C or higher), non-heated and non-cooled, and cooled (for example, above 5°C and below room temperature or 5°C or lower) food and beverages can be used.

[0059] Such food and beverages can be manufactured using the above-mentioned processed liquid composition containing oat protein, and appropriately through a flavoring step and / or a cooking step. For the specific methods used in the flavoring step and the cooking step, those skilled in the art can appropriately determine them according to the food and beverage in its final form.

[0060] Examples Hereinafter, examples will be given to specifically illustrate the present invention, but the present invention is not construed as being limited to the following examples.

[0061] [A. Materials and Enzymes] The following materials and enzymes are used.

[0062] [Table 1]

[0063] [B. Enzyme Activity Assay Method] [B-1. Protein Deamidase] The protein deamidase activity value is measured by the following method.

[0064] To 1 mL of 0.2 M phosphate buffer (pH 6.5) containing 30 mM Z-Gln-Gly, 0.1 mL of the sample solution containing protein deamidase is added. After incubation at 37 °C for 10 minutes, 1 mL of 0.4 M TCA solution is added to stop the reaction. As a blank, to 1 mL of 0.2 M phosphate buffer (pH 6.5) containing 30 mM Z-Gln-Gly, 1 mL of 0.4 M TCA solution is added, and then 0.1 mL of the sample solution containing protein deamidase is further added, followed by incubation at 37 °C for 10 minutes.

[0065] For the obtained solution, Ammonia test Wako (FUJIFILM Wako Pure Chemical Corporation) is used to measure the amount of ammonia generated in the reaction solution. From the standard curve showing the relationship between ammonia concentration and absorbance (630 nm) prepared using an ammonia standard solution (ammonium chloride), the ammonia concentration in the reaction solution is determined.

[0066] The amount of enzyme that generates 1 μ mol of ammonia in 1 minute is defined as 1 unit (1 U), and the activity of protein deamidase is calculated according to the following formula. In the formula, the volume of the reaction solution is 2.1, the volume of the enzyme solution is 0.1, and Df is the dilution factor of the enzyme solution. Additionally, 17.03 is the molecular weight of ammonia.

[0067] [Equation 1] Protein deamidase activity (U / mL) = Ammonia concentration in the reaction solution (mg / L) × (1 / 17.03) × (Volume of the reaction solution / Volume of the enzyme solution) × (1 / 10) × Df [B-2. α -Amylase] α The -amylase activity value is measured by the following method.

[0068] After heating 10 mL of a 1% potato starch substrate solution (0.1 mol / L acetic acid (pH 5.0)) at 37°C for 10 minutes, 1 mL of a sample solution containing α α-amylase was added, and immediately mixed by shaking. After leaving this liquid at 37°C for 10 minutes, 1 mL of this liquid was added to 10 mL of a 0.1 mol / L hydrochloric acid solution, and immediately mixed by shaking. Next, 0.5 mL of this liquid was weighed, 10 mL of a 0.0002 mol / L iodine test solution (Japanese Pharmacopoeia) was added, and after mixing by shaking, using water as a control, the absorbance (AT) at a wavelength of 660 nm was measured. In addition, 1 mL of water was added in place of the sample solution, and the operation was carried out in the same manner to measure the absorbance (AB). Furthermore, the 0.0002 mol / L iodine test solution (Japanese Pharmacopoeia) was prepared as follows: 10 mL of water was added to 12.7 g of iodine and 25 g of potassium iodide, stirred and mixed well, and then water was added to make 100 mL, and it was further diluted 2500-fold with water to prepare it. The amount of enzyme that reduces the color development produced by iodine of potato starch by 10% within 1 minute was defined as 1 unit (1 U).

[0069] [Equation 2] α α-amylase activity (U / g, U / mL) = (AB - AT) / AB × 1 / W AT: Absorbance of the reaction solution AB: Absorbance of the blank solution W: Amount of the sample in 1 mL of the sample solution (g or mL) [B-3. β α-amylase] β The α-amylase activity value was measured by the following method.

[0070] Using potato starch as a substrate, it was pre-dried at 105°C for 2 hours, 1.0 g of its dried product was weighed, 20 mL of water was added, and while stirring, 5 mL of a sodium hydroxide solution (2 mol / L) was slowly added to form a paste. Next, while stirring, it was heated in a boiling water bath for 3 minutes, and then 25 mL of water was added. After cooling, a hydrochloric acid solution (2 mol / L) and a hydrochloric acid solution (0.1 mol / L) were added for neutralization, 10 mL of a 1 mol / L acetic acid - sodium acetate buffer solution (pH 5.0) was added, and further water was added to make 100 mL, which was used as the substrate solution.

[0071] 10 mL of the substrate solution was weighed, heated at 37°C for 10 minutes, and a sample solution containing β1 mL of the sample solution of α-amylase was immediately shaken and mixed. After heating for 10 minutes at the same temperature, 4 mL of Fehling's reagent was further added and gently shaken and mixed. After heating in a boiling water bath for 15 minutes, it was cooled to below 25 °C, and 2 mL of potassium iodide test solution (a solution prepared by dissolving 30 g of potassium iodide in 70 mL of water) and 2 mL of sulfuric acid (1→6) were added to prepare a test solution. In addition, Fehling's reagent is a reagent prepared at the time of use by mixing a 500 mL copper solution prepared by weighing 34.66 g of fine crystals of copper (II) sulfate pentahydrate and dissolving it in water, and a 500 mL alkaline tartrate solution prepared by weighing 173 g of (+)-sodium potassium tartrate tetrahydrate and 50 g of sodium hydroxide and dissolving them in water, in a ratio of 1 volume of copper solution to 1 volume of alkaline tartrate solution.

[0072] In addition, 10 mL of water was used instead of the substrate solution, and the operation was carried out in the same manner as the preparation of the test solution to prepare a comparison solution. For the test solution and the comparison solution, 0.05 mol / L sodium thiosulfate solution was used to titrate the free iodine. When the titration was approaching the end point, 1 to 2 drops of soluble starch solution were added, and the moment when the resulting blue color disappeared was taken as the end point. The amount of enzyme that increased the reducing power equivalent to 1 mg of glucose produced within 1 minute was taken as 1 unit (1 U), and it was calculated by the following mathematical formula.

[0073] [Equation 3] β α-Amylase activity (U / g, U / mL) = amount of glucose (mg) × 1 / 10 × 1 / M Amount of glucose (mg) = (b - a) × 1.6 × f a: Titration value of the enzyme reaction solution (mL) b: Titration value of the blank solution (mL) 1.6: 1 mL of 0.05 mol / L sodium thiosulfate is equivalent to 1.6 mg of glucose 1 / 10: Unit conversion coefficient of the reaction time (minutes) M: Amount of the sample in 1 mL of the sample solution (g or mL) f: Factor of 0.05 mol / L sodium thiosulfate solution (for quantification) [Liquid composition containing oat protein] The liquid composition containing oat protein was prepared as follows.

[0074] 18.1 g of oat flour and 150 g of water were mixed to prepare a suspension in a 200 mL Erlenmeyer flask. The suspension was adjusted so that the pH (25 °C) became 6.5, 7.0, or 7.5, and 10 U of α α-amylase was added per 1 g of starch and 0.09 U of βα - amylase was reacted at 54 °C for 1 hour. Thus, a liquid composition containing oat protein (oat milk) was obtained.

[0075] Protein deamidase (PG) was added to the obtained liquid composition containing oat protein in an amount of 5 U per 1 g of protein. After adjusting the pH to 8.0 (25 °C), the reaction was carried out at 60 °C for 1 hour. After the reaction, heat treatment was performed at 95 °C for 5 minutes to inactivate the enzyme. Then, centrifugation was carried out at 1000 rpm for 1 minute, and the supernatant (enzymatically treated liquid composition) was recovered.

[0076] The recovered supernatant (enzymatically treated liquid composition) was adjusted to pH (25 °C) of 5.0, 5.5, 6.0, 6.5, 7.0, 7.5 or 8.0 to prepare a processed liquid composition containing oat protein (processed oat milk). As a pH regulator, high-concentration NaOH and HCl aqueous solutions were used, so there was almost no increase in the liquid volume accompanied by pH adjustment.

[0077] In addition, except for not performing the enzyme treatment based on protein deamidase (PG), the same operations were carried out to prepare a liquid composition containing oat protein without PG treatment (oat milk without PG treatment).

[0078] [C. Foaming property and foam stability] Regarding the obtained processed oat milk and oat milk without PG treatment, the foaming property and foam stability were evaluated under the following conditions.

[0079] [C-1. Foaming property] 50 mL of the processed oat milk and oat milk without PG treatment were homogenized at 18000 rpm for 30 minutes respectively. Immediately afterwards, they were transferred to a 100 mL graduated cylinder, and the volume VF0 including foam was measured. The foaming property was calculated using the following calculation formula.

[0080] [Equation 4] Foaming property (%) = 100×(VF0 - 50) / (50) Furthermore, the relative value of the foaming property at each pH with the foaming property at pH 8.0 (when there is no pH reduction process) of the processed oat milk and oat milk without PG treatment set as 1 was derived as the "foaming property improvement index 1". In addition, the relative value of the foaming property of the processed oat milk with the foaming property of the oat milk without PG treatment at each pH set as 1 was derived as the "foaming property improvement index 2". The results are shown in Table 2A, Table 2B, Table 3A, Table 3B, Table 4A and Table 4B according to the pH during amylase treatment.

[0081] [Table 2A]

[0082] [Table 2B]

[0083] As shown in the foaming property improvement index 1 of Table 2A and Table 2B, the processed oat milk (Examples 1 to 6) has improved foaming property by reducing the pH after PG treatment. Moreover, as shown in Table 2A, when the pH is reduced to 5.0, the foaming property deteriorates significantly (Comparative Example 7), but as shown in the foaming property improvement index 2 of Table 2B, the processed oat milk exhibits excellent foaming property even when the pH is reduced to 5.0 after PG treatment (Example 6).

[0084] [Table 3A]

[0085] [Table 3B]

[0086] [Table 4A]

[0087] [Table 4B]

[0088] Similarly, as shown in the foaming property improvement index 1 of Table 3A, Table 3B, Table 4A, and Table 4B, the processed oat milk (Examples 7 to 14) has improved foaming property by reducing the pH after PG treatment.

[0089] [C-2. Foam stability] 50 mL of processed oat milk and oat milk without PG treatment were homogenized at 18,000 rpm for 30 minutes, respectively. Immediately thereafter, they were transferred to a 100 mL graduated cylinder, and the volume VF0 including foam was measured. After 30 minutes, the volume VF30 including foam was measured in the same way, and the foam stability was calculated using the following formula.

[0090] [Equation 5] Foam stability (%) = 100 × (VF30 / VF0) Moreover, the relative value of the foam stability at each pH with the foam stability at pH 8.0 of the processed oat milk and the oat milk without PG treatment being set to 1 was derived as the "foam stability improvement index 1". In addition, the relative value of the foam stability of the processed oat milk with the foam stability of the oat milk without PG treatment at each pH being set to 1 was derived as the "foam stability improvement index 2". The results are shown in Table 5A, Table 5B, Table 6A, and Table 6B according to the pH during amylase treatment.

[0091] [Table 5A]

[0092] [Table 5B]

[0093] As shown in Table 5A and Table 5B, the foam stability of processed oat milk decreased through PG treatment (Comparative Example 8), but by lowering the pH after PG treatment, the foam stability was improved (Examples 1 to 6). When the pH was lowered to less than 6.5, the degree of improvement in the foam stability became equal to or higher than that in the case without PG treatment (Examples 3 to 6). Moreover, as shown in Table 5A, when the pH was lowered to 5.0, the foam stability deteriorated (Comparative Example 7), but as shown by the foam stability improvement index 2 in Table 5B, even when the pH of processed oat milk was lowered to 5.0 after PG treatment, excellent foam stability was exhibited, and the degree exceeded that in the case without PG treatment (Example 6).

[0094] [Table 6A]

[0095] [Table 6B]

[0096] Similarly, as shown in Table 6A and Table 6B, the foam stability of processed oat milk decreased through PG treatment (Comparative Example 14), but by lowering the pH after PG treatment, the foam stability was improved (Examples 8 to 10, Example 15), and when the pH was lowered to less than 6.5, the degree of improvement in the foam stability became equal to or higher than that in the case without PG treatment (Examples 9, 10, Example 15).

Claims

1. A method for producing a processed liquid composition containing oat protein, characterized in that: include: an enzyme treatment step, wherein a protein deamidase is allowed to act on a liquid composition containing oat protein at a predetermined pH to obtain an enzyme-treated liquid composition; and The pH lowering step comprises lowering the pH of the enzyme-treated liquid composition to obtain a processed liquid composition containing oat protein.

2. The manufacturing method according to claim 1, wherein: The value obtained by subtracting the pH of the processed oat protein-containing liquid composition at 25°C from the prescribed pH at 25°C is 0.2 to 4.

3. The manufacturing method according to claim 1, wherein: The prescribed pH at 25°C is 5.0 to 9.

0.

4. The manufacturing method according to claim 1, wherein: The pH of the processed liquid composition containing oat protein at 25° C. is 4-7.

5.

5. The manufacturing method according to claim 1, wherein: The content of oat protein in the liquid composition containing oat protein is 0.01 wt % to 15 wt %.

6. The manufacturing method according to claim 1, wherein: The liquid composition containing oat protein is oat milk.

7. The manufacturing method according to claim 1, wherein: The protein deamidase is protein glutaminase.

8. The manufacturing method according to claim 1, wherein: The protein deamidase is used in an amount of 0.05 U or more per 1 g of oat protein contained in the oat protein-containing liquid composition.

9. A food or beverage containing oat protein, characterized in that: The oat protein-containing liquid composition is produced using the processed oat protein-containing liquid composition obtained by the production method according to claim 1.

10. The food or beverage containing oat protein according to claim 9, wherein The processed liquid oat protein-containing composition is forced to foam.

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