WO2005120244A1 - Method of producing soybean protein hydrolysate - Google Patents

Abstract

It is intended to provide a soybean protein hydrolysate which has an excellent flavor with lessened undesirable tastes such as unpleasant smell and bitterness and stickiness to the tongue. The existing soybean protein hydrolysate is produced by extracting soymilk from defatted soybeans, removing whey components therefrom by isoelectric precipitation under acidic conditions (acid precipitation) to give acid-precipitated curd, and then hydrolyzing it by an enzymatic reaction. Namely, protein is subjected to the acid precipitation step before the hydrolysis. By using soybean protein, which is not subjected to such an acid precipitation step, as a substrate, a soybean protein hydrolysate having largely lessened unpleasant smell and bitterness and stickiness to the tongue can be provided.

Description

 Specification

 Method for producing soybean protein hydrolyzate

 Technical field

 The present invention relates to a method for producing a soybean protein hydrolyzate having a good taste, and particularly to a method for producing a soybean protein hydrolyzate without passing through a step of acid precipitation (isoelectric point precipitation) of soybean protein. .

 Background art

 [0002] Protein hydrolyzate of soybean is a vegetable protein source and has recently been attracting attention due to its nutritional physiological effects such as recovery from fatigue and higher digestibility and absorption compared to undegraded protein. Re, the material. However, soybean protein hydrolyzate has its own unpleasant taste and odor, and has been an issue to be improved when processed into various foods and drinks.

[0003] In order to reduce such unpleasant tastes, such as bitterness, sticking to the tongue, and unpleasant odor, many studies have conventionally been made. Methods using activated carbon (Patent Documents 1 and 2) Disclosed are a method using an ion exchange resin and a method using a synthetic adsorbent (Patent Documents 3, 4, 5, and 6).

. However, these methods have problems such as complicated production steps and a large amount of water required for washing resins and the like (including activated carbon and adsorbents).

[0004] (References)

 Patent Document 1: Japanese Patent Publication No. 56-52543

 Patent Document 2: JP-A-3_272694

 Patent Document 3: JP-A-4_190797

 Patent Document 4: JP-A-4-341341

 Patent Document 5: JP-A-4-45750

 Patent Document 6: JP-A-7_264993

 Patent Document 7: WO2004 / 013170

 Patent Document 8: JP 2001-238693

 Patent Document 9: WO2004 / 017751

Disclosure of the invention Problems the invention is trying to solve

 [0005] It is an object of the present invention to provide a flavorful soybean protein hydrolyzate having reduced unpleasant odor, bitterness, and bad taste such as stickiness to the tongue.

 Means for solving the problem

 [0006] Conventionally, a soybean protein hydrolyzate has been prepared by extracting soymilk from defatted soybeans, subjecting the soymilk to acidic isoelectric precipitation (acid precipitation), removing the whey component to obtain an acid precipitation card, and then subjecting this to an enzymatic reaction. Manufactured by hydrolysis. That is, the protein extracted from okara goes through an acid precipitation step before hydrolysis. The present inventors have conducted intensive studies on the above-mentioned problems, and as a result, a soybean protein hydrolyzate using a soybean protein that has not undergone the acid precipitation step as a substrate has a soybean protein that has undergone the acid precipitation step as a substrate. The present inventors have found that unpleasant odor, bitterness, and sticking to the tongue are significantly reduced as compared with the case where the present invention is performed, and have completed the present invention.

 [0007] That is, the present invention provides

 1. Concentrated soy protein power A method for producing a soy protein hydrolyzate that extracts protein and hydrolyzes the resulting soy protein extract without going through an acid precipitation step.

 2. The method for producing a soybean protein hydrolyzate according to the above 1, wherein the soybean protein extract before hydrolysis is heat-sterilized.

 3. The method for producing a soybean protein hydrolyzate according to the above item 1, wherein the protein extraction is a countercurrent extraction method.

4. Hydrolyzate of soybean protein obtained by extracting and hydrolyzing protein from concentrated soybean protein by countercurrent extraction method,

 5. A soybean protein hydrolyzate according to the above item 4, wherein the crude protein content per dry solid content is 80% by weight or more.

 The invention's effect

 [0008] The present invention provides a soybean protein hydrolyzate having a good flavor with reduced unpleasant odor, bitterness, and bad taste such as stickiness to the tongue. Another object of the present invention is to provide a method for producing a soybean protein hydrolyzate, which does not require a conventional complicated concentration step, in which the protein is once insolubilized by acid precipitation, and the pH is adjusted again to solubilize the protein.

BEST MODE FOR CARRYING OUT THE INVENTION The defatted soybean of the present invention has a low NSI (nitrogen solubility index) of 60 or more, particularly 80 or more, even if defatted soybeans defatted with a generally available solvent such as hexane are used. The use of denatured defatted soybeans is preferred because the protein can be easily extracted. Concentrated soy protein can be obtained by washing raw soybeans, especially defatted soybeans, with an acidic aqueous medium or alcohol, performing solid-liquid separation, and removing whey components. A dried product thereof is also commercially available as an acid concentrate / alcohol concentrate, and in the present invention, a product obtained by adding water thereto may be used as a starting material.

 [0010] The acid washing is capable of dissolving whey components containing soy albumin as a main component. A protein component containing soy globulin as a main component, that is, a pH range in which storage proteins are not eluted, may be used. If the pH is preferably 4.2 to 4.8, soy globulin is hardly eluted into whey, so that the yield of protein components containing soy globulin as a main component is good. The type of acid used for the acidification is not particularly limited, and examples thereof include inorganic acids such as phosphoric acid, hydrochloric acid, and sulfuric acid, and organic acids such as citric acid, malic acid, and lactic acid. They can be used alone or in combination of two or more.

 [0011] The acid washing may be performed by immersing or stirring the defatted soybean in the above-mentioned acidic aqueous medium to bring it into contact. This washing can increase the amount of crude protein per solid. The higher the amount of crude protein per solid, the higher the protein concentration of the extract obtained in the extraction process described below.Therefore, the amount of crude protein per solid should be 65% or more, especially 70% or more. Is preferred. The acid washing method is not particularly limited, and a conventionally known method can be used. The number of times of washing is not particularly limited, and multi-stage washing can be performed. Among them, a multi-stage washing method (countercurrent washing method) in which acid washing is performed in multiple systems in parallel, the defatted soybean and the acid washing solution are brought into contact with each other by moving them in opposite directions, and solid-liquid separation is performed. preferable. According to the countercurrent washing method, not only can the washing be performed with a smaller amount of washing solution, but also the concentration efficiency of the protein can be increased, and the crude protein content per solid content by washing can be easily increased. The number of times of washing by the countercurrent washing method is preferably two or three times.

The washing temperature is preferably 10 to 60 ° C., more preferably 20 to 50 ° C., and still more preferably 40 to 50 as long as the temperature is within a temperature range where the protein is not denatured. C, and the washing time is, for example, 5 to 60 minutes, preferably 10 to 30 minutes. By this acid washing treatment, it was solubilized together with whey protein. Sugars, salts, pigments, etc. can also be separated and removed.

 [0013] The method of solid-liquid separation following acid washing is not particularly limited, and a conventionally known separation apparatus may be used. It may be centrifuged by a centrifugal separator, or may be separated by a filter press, a screw press or the like. Addition of an emulsifier during acid washing improves the fluidity of the slurry, improves the solid-liquid separation, and facilitates separation. The type of emulsifier is not particularly limited, but glycerin fatty acid esters of HLB 2 to 7 can be suitably exemplified, and the concentration thereof is preferably 0.001 to 0.1% by weight based on the low-denatured defatted soybean. preferable.

 [0014] The protein is extracted from the concentrated soybean protein obtained by separating the insoluble fraction in this way. In extraction, protein is eluted into concentrated soybean protein water and separated from okara components, which are extraction residues. The extraction may be carried out under neutral to alkaline conditions, but the pH is preferably 6.5 to 8.5, more preferably pH 7.0 to 8.0. To adjust the pH, hydroxides, carbonates, and bicarbonates of alkali metals and alkaline earth metals such as sodium hydroxide and potassium hydroxide can be used. Water can contain other components as long as it does not hinder the extraction of protein from concentrated soy protein. For example, a solution obtained by adding alcohol to water (aqueous alcohol), a solution obtained by adding salt to water and adding a salt, or the like can be used. You can.

 [0015] The extraction temperature is preferably from 10 to 70 ° C, more preferably from 40 to 65 ° C, and even more preferably from 45 to 65 ° C. If the extraction temperature is too high, the soybean protein is denatured by heat. If the extraction temperature is too low, the viscosity increases, the separability between the extract and the extraction residue decreases, and the protein extraction rate also decreases. In particular, when the growth of microorganisms at the time of extraction becomes a problem, it is preferable to extract at 50 ° C or higher because growth can be suppressed. The extraction time varies depending on the extraction scale, stirring conditions, and the like. Usually, 10 to 120 minutes is preferable, and 20 to 40 minutes is more preferable.

[0016] The extraction method in the present invention is not particularly limited. For example, in one system, concentrated soybean protein is dispersed in water and the protein is extracted by stirring or the like, and the protein extract and the okara component, which is the extraction residue, are separated. Good. This may be repeated a plurality of times to further extract the protein remaining in the okara component. However, the protein concentration in the extract cannot be increased simply by repeating the extraction step multiple times in one system. The most commonly used method for increasing the protein concentration of a protein extract is a method in which the extract is made acidic and the protein is separated and concentrated by so-called acid precipitation that precipitates the protein at the isoelectric point. However, the present invention is characterized in that the extracted protein does not pass through the step of acid precipitation, whereby the effects of the present invention can be obtained. According to the countercurrent extraction method described below, the protein concentration in the extract can be easily increased, and no particular concentration step is required. Therefore, when it is necessary to increase the protein concentration, a countercurrent extraction method may be used.

 [0017] The countercurrent extraction method is a multistage extraction method in which extraction is performed in parallel in a plurality of systems, and an extract is brought into contact between these systems by moving an extract relatively in opposite directions. Therefore, the countercurrent extraction method also includes a multistage extraction method in which only the extraction medium that does not move the extract is moved and the extract is brought into contact with the extract sequentially. Here, the extraction medium refers to water newly added for extraction or an extract containing a protein already used for extraction, and the extract to be extracted refers to the above-mentioned concentrated soybean protein or the extract already extracted at least once. Refers to the extraction residue received. The countercurrent extraction method is disclosed in Patent Document 7. As a preferred aspect of the powerful countercurrent extraction method, a countercurrent extraction method in which extraction is performed while the concentration difference between the extraction medium and the extract is always kept constant, for example, a new countercurrent extraction method with the highest protein concentration The concentrated soybean protein is brought into contact with the extract with the highest solid content that has already been used for the extraction process, and the newly introduced water is brought into contact with the extraction residue that has already been subjected to the extraction process and has the lowest protein concentration. That can be S.

 [0018] The amount of water used for the countercurrent extraction is not particularly limited, but is preferably 7 times by weight or less, preferably 2 to 6 times by weight, particularly preferably 3 to 4 times by weight, based on the solid content of the concentrated soybean protein. . This is not the amount of liquid at the time of initial extraction, but the total amount of liquid during steady-state extraction.

 The number of extractions in the countercurrent extraction method may be two or more, but is preferably about two or three times, and particularly preferably three times. According to the three-stage countercurrent extraction method in which the extraction is performed three times, the protein remaining in the extraction residue can be reduced, and the recovery rate of the protein can be improved.

[0020] Further, as the countercurrent extraction method, a pH gradient countercurrent extraction method, a continuous countercurrent extraction method, and a pH gradient continuous countercurrent extraction method can also be adopted. Here, the pH gradient countercurrent extraction method refers to a multistage extraction method in which the pH of an aqueous medium is gradually increased or decreased sequentially and then brought into contact with a soybean material in the countercurrent extraction method. However, in the three-stage countercurrent extraction method, a three-stage extraction method in which the pH is increased (lowered) in the second extraction stage compared to the first extraction stage and the pH is increased (decreased) in the third extraction stage than in the second extraction stage. Examples can be given. The above continuous countercurrent extraction method The term “extraction method” refers to an extraction method in which a multistage extraction step is continuously performed in the countercurrent extraction method. The pH gradient continuous countercurrent extraction method refers to an extraction method in which a multistage extraction step is continuously performed in the pH gradient countercurrent extraction method. According to these countercurrent extraction methods, the yield can be improved at lower cost.

[0021] The alkali used for pH adjustment in extraction can be used without any particular limitation as long as it is edible. For example, sodium hydroxide can be used, and potassium hydroxide may be used in consideration of nutritional aspects. .

 [0022] The soybean protein extract can be subjected to sterilization before the enzymatic reaction described below following the extraction. At the time of the enzymatic reaction, depending on the conditions, germs and the like often proliferate and may impair the flavor of the decomposition product. Sterilization prior to the enzymatic reaction can make the flavor better. The sterilizing apparatus used in the sterilizing step is not particularly limited as long as it is a normal sterilizing apparatus. For example, a continuous direct heat sterilizing apparatus of a steam injection system can be suitably used. Specific examples of sterilization conditions include heat sterilization at a temperature of 100 to 160 ° C, preferably 105 to 145 ° C, for 3 seconds to 3 minutes.

 [0023] As described above, protein is extracted from concentrated soybean protein, and the amount of crude protein per solid content of the obtained soybean protein extract is preferably 80% by weight or more, more preferably 85% or more. Replying to The strong concentration is, for example, about 50% by weight of the crude protein in soymilk from which whey is not separated, so that a considerably high concentration can be obtained, and a high protein hydrolyzate can be obtained.

 [0024] The obtained soybean protein extract is subsequently subjected to a hydrolysis reaction with a protease (protease). The protein concentration of the soybean protein solution at the time of the enzymatic reaction is suitably 1% to 30% by weight, preferably 5% to 15% by weight, more preferably 8% to 12% by weight. The protein concentration can be adjusted to this range by appropriately selecting extraction conditions such as extraction pH, extraction temperature, extraction time, amount of extract, and number of extractions. If the concentration is too low, there is no problem in enzymatic degradation, but it will increase the production cost of soybean protein hydrolyzate with poor productivity. Also, if the concentration of the soybean protein solution is too high, a large amount of enzyme is required for the reaction to proceed sufficiently, which is also undesirable.

[0025] The alkali for adjusting the pH of the hydrolyzed solution is not particularly limited, and sodium hydroxide may be used, or potassium hydroxide may be used in consideration of nutritional aspects. . In addition, acids can be used without particular limitation, and examples thereof include inorganic acids such as phosphoric acid, hydrochloric acid, and sulfuric acid, and organic acids such as citric acid, malic acid, and lactic acid. These may be used alone or in combination of two or more. Although an organic acid such as citric acid can be used in view of flavor, it is preferable to use exoprotease or endoprotease alone or in combination. It can be of animal, plant or microbial origin. Specifically, serine proteases (trypsin, chymotrypsin derived from animals, subtilisin derived from microorganisms, carboxypeptidase, etc.), thiol proteases (papain, fusin, bromelain, etc. derived from plants), carboxyproteases (pepsin derived from animals, etc.) can be used. Can be used. More specifically, examples of enzymes containing endoprotease include “Alcalase” derived from Bacillus licheformis (Novozymes Japan Ltd.) 「“ Protin A ”derived from Bacillus sbutyls (Daiwa Kasei Co., Ltd.) “Proteaze 3” (manufactured by Amano Enzyme Co., Ltd.), “Bioprase SP-15FG” (manufactured by Nagase ChemteX Corporation), and “Protin AC-10” (manufactured by Daiwa Kasei Co., Ltd.) Aspergillus oryzae-derived protease

M "," Proteaze Ichihachi "(manufactured by Amano Enzyme Co., Ltd.) and" Actinase "derived from Streptomyces 'glycease' (manufactured by Kaken Pharmaceutical Co., Ltd.).

 [0027] The hydrolysis conditions of the present invention vary depending on the type of the protease used. The amount and time of addition may be determined so that the target decomposition rate is achieved in the action pH range and the action temperature range of each protease. From the viewpoint of use of a salt-restricted diet (for example, a tube feeding diet), a pH of 5 to 10, and preferably a pH of 6 to 9, is preferable because salt formation due to neutralization can be reduced. When the enzyme is allowed to act after maintaining the pH in an alkaline region of 8 to 9 for 5 minutes or more, preferably 20 to 90 minutes, a high-decomposition product can be efficiently obtained by a short-time decomposition reaction.

 [0028] The degree of hydrolysis is performed until the soybean protein decomposition rate, which is the solubilization rate of 15% trichloroacetic acid in the protein component, is about 20 to 98%, more usually about 50 to 90%. The time for which the protease is allowed to act varies depending on the activity and amount of the protease used, but is usually about 5 minutes to 24 hours, preferably about 30 minutes to 9 hours, more preferably about 1 hour to 4 hours. It can be. If the enzymatic decomposition time is too long, decay is likely to occur.

[0029] If necessary, trace amounts of insolubles present in the hydrolyzed soybean protein solution with time These separation steps may be added to prevent precipitation as sediment or precipitation. The means of separating insolubles may be by filtration means such as filter press or membrane separation, but most usually centrifugation is used, especially using a centrifuge or liquid cyclone capable of continuous processing. Can be done.

 [0030] The pH after the enzymatic reaction varies depending on the reaction conditions. The force is usually in the range of pH 3 to 8. When separating insolubles, preferably ρΗ4 to 6.2, more preferably ρΗ4.5 to 5.5. It is appropriate to do so. Since insoluble matter including undecomposed matter tends to agglomerate near the isoelectric point of soybean protein, in the ρΗ region, the cohesiveness of the insoluble matter is increased, and the separability during separation is increased. be able to. This operation is so-called acid precipitation. Since the protein precipitated by the acid is removed in the separation step, it is not particularly problematic to enter the acid precipitation step here. In addition, when the decomposition solution is supplemented with chlorides such as calcium and magnesium, salts such as sulfates, alkaline earth metal compounds such as hydroxides, or protein flocculants such as sodium polyacrylate, alginic acid, and chitin-chitosan, The cohesiveness of the insolubles can be increased to enhance the separability. In addition, even if the step of the heat treatment disclosed in Patent Document 8 may be performed, this step can also enhance the cohesiveness of the insoluble matter and the separability.

 [0031] If necessary, the phytic acid of the hydrolyzate can be reduced. If the reduction of phytic acid involves hydrolysis of phytate using phytase, which is preferred, and hydrolysis of phytate using phytase, the order of phytate degradation can be any combination. May be. The reaction conditions of the phytase species to be used may be the same as those disclosed in Patent Document 9. By reducing phytic acid, absorption of trace metals such as calcium can be promoted.

 [0032] After the enzymatic reaction, the enzyme is dismissed. The enzyme can be deprived by heat treatment (usually at 70 ° C .: at 150 ° C. for 30 minutes to several seconds). The heat sterilization step following the hydrolysis reaction can also serve as the enzyme disappointment.

[0033] The soybean protein hydrolyzate solution obtained as described above can be used as it is or after being concentrated depending on the application, but can also be subjected to a sterilization / drying step. The sterilization device used in the powerful sterilization-drying process is not particularly limited as long as it is a normal sterilization device. For example, a continuous direct heat sterilization device of a steam injection system is preferably used. be able to. Specific examples of sterilization conditions include a temperature of 100 to 160 ° C., preferably 105 to 145 ° C., for about 3 seconds to 3 minutes. The drying method is not particularly limited as long as it is a conventionally known drying method, and preferred examples include freeze drying, spray drying, and drying under reduced pressure. Prior to sterilization and drying, various compounding components such as an emulsifying component, a stabilizing component, a nutritional component, and a sweet component can be added.

[0034] The analytical methods used in the present invention are described below.

 • TCA solubility

 In a solution that was dispersed in water so that the protein content was 1.0% by weight and stirred well, the ratio of 15% triclomouth acetic acid (TCA) -soluble protein to the total protein was determined by a protein determination method such as the Kjeldahl method or the Lowry method. Measured.

 Example

 Hereinafter, the present invention will be described more specifically with reference to Examples, but the technical scope of the present invention is not limited to these Examples. In addition,% in an Example shows a weight% unless there is particular notice.

 (Example 1)

 Fatty acid monoglyceride as emulsifier (Taiyo Kagaku “Sunsoft O_30V” HLB = 2.8) 2 kg of low-denatured defatted soybean flakes of NSI90 is gradually added to 12 kg of 45 ° C warm water in which 0.6 g is dispersed. Was. After gently stirring for 10 minutes while adjusting to pH 4.2 with hydrochloric acid, the eluted whey components were separated and removed by a centrifuge (1500 G, 10 minutes) to obtain 4 kg of concentrated soy protein. To 4 kg of this concentrated soybean protein, 12 kg of hot water at 45 ° C. was added. Gentle stirring for 10 minutes · After washing, the eluted whey components are separated and removed with a centrifuge (1500G, 10 minutes), whey 12kg, water content 63%, crude protein content per solid content 72% 4 kg of concentrated soybean protein was obtained. This was divided into four parts each of lkg to obtain Al, A2, A3, and A4, which were subsequently subjected to three-stage countercurrent extraction.

 [0037] The three-stage countercurrent extraction was based on a pH gradient three-stage countercurrent extraction. All extractions were performed at 60 ° C, solid-liquid separation was performed by centrifugation at 1500 G for 10 minutes, and the pH of the extract was adjusted using a 20% sodium hydroxide solution.

[0038] Add 2 kg of water to lkg (A1) of the above-mentioned concentrated soybean protein, adjust the pH to 7.0, and adjust for 30 minutes. The mixture was stirred and centrifuged to obtain an extraction residue R-1 and an extract E-1 (solid content 8.0%) 2. Okg. 2 kg of water was added to the extraction residue R-1, stirred for 15 minutes, and centrifuged to obtain an extraction residue R-2 and an extract E-2 (2.5% solid content) 2. Okg.

 Next, 2 kg of extract solution E-1 was added to lkg of concentrated soybean protein (A2), adjusted to pH 7.0, stirred for 30 minutes, centrifuged, and extracted with extract residue R-3. Liquid E_ 3 (solid content 13.5%) 2. Okg was obtained. 2 kg of extract E-2 was added to this extract residue R-3, stirred for 30 minutes, and centrifuged to obtain 2.2 kg of extract residue R-4 and extract E_4 (6.0% solids). . Further, 1.5 kg of water was added to the extraction residue R-4, stirred for 15 minutes, and centrifuged to obtain 1.6 kg of an extraction residue R_5 and an extract E_5 (solid content 2.0%). .

 [0040] Further, 2.2 kg of extract solution E-4 was added to lkg of concentrated soybean protein (A3), adjusted to pH 7.0, stirred for 30 minutes, centrifuged, and extracted with extraction residue R-6. Liquid E_6 (solid content: 12.0%) was obtained as 2.2 kg. 1.6 kg of Extract E-5 was added to this Extract Residue R-6, stirred for 30 minutes, centrifuged, and 1.7 kg of Extract Residue R-7 and Extract E-7 (6.0% solids) were added. Got. Further, 1.5 kg of water was added to the extraction residue R-7, stirred for 15 minutes, and centrifuged to separate 1.6 kg of the extraction residue R-8 and the extraction solution E-8 (solid content 2.0%). Obtained.

 Further, 1.7 kg of extract E-7 was added to 1 kg of concentrated soybean protein (A4), adjusted to pH 7.0, stirred for 30 minutes, and centrifuged to extract extract residue R-9 and extract E — 9 (12.5% solids) 2. Okg. 1.6 kg of Extract E-8 is added to this Extract Residue R-9, stirred for 15 minutes, centrifuged, and Extract Residue R-10 and Extract E-10 (5.0% solids) 1.7 kg And got.

 [0042] Of the extracts obtained as described above, the extract E-3, E-6, and E-9 having a solid content of 10% or more were mixed, and then the solid content was adjusted to 9%. The pH was adjusted to 7.0, and the mixture was sterilized at 140 ° C for 10 seconds using a steam injection continuous direct heat sterilizer to obtain a soybean protein extract. The crude protein mass per dry solid was 86.7%.

[0043] To the soybean protein extract obtained through the acid precipitation step obtained as described above, "Bioprase SP-15FG" (manufactured by Nagase ChemteX Corporation) was used as a protease at an EZS ratio of 1.8%. The mixture was added and hydrolyzed for 4 hours at 50 ° C (15% TCA solubility, 65%). After adding the citric acid to the soybean protein hydrolyzed solution after the enzymatic reaction to adjust the pH to 4.5, the mixture was centrifuged (1500 G, 15 minutes) to separate and remove insoluble matter including undecomposed matter. The resulting centrifuged supernatant is Water was removed by freeze drying after sterilization by heating at 140 ° C for 10 seconds using a continuous direct heat sterilizer of team injection system.

(Example 2)

"Alcalase" (produced by Novozymes Japan Ltd.) was added as a proteolytic enzyme to the soybean protein extract prepared in Example 1 at an EZS ratio of 0.05% and hydrolyzed at 50 ° C for 4 hours (15). / ₀ TCA solubility, 30%). After the enzyme reaction, the soybean protein hydrolyzate was deactivated at 140 ° C for 10 seconds using a steam injection continuous direct heat sterilizer, and then spray-dried with a spray drier.

(Example 3)

The soybean protein extract prepared in Example 1 was spray-dried to prepare a powdery separated soybean protein having a water content of 5%, and then an 8% solution of pH 8.8 was prepared. After keeping the prepared solution at 55 ° C for 20 minutes, the EZS ratio was 2 as the protease. "Bioprase SP_15FG" (manufactured by Nagase ChemteX Corporation) was added at a ratio of / ₀ to hydrolyze at 55 ° C for 3 hours (15% TCA solubility, 85%). Cyanic acid was added to the soybean protein hydrolyzed solution after the enzyme reaction to adjust the pH to 4.5, and then centrifuged (1500 G, 15 minutes) to separate and remove insoluble matter including undegraded matter. The obtained centrifuged supernatant was sterilized at 140 ° C for 10 seconds using a continuous direct heat sterilization apparatus of a steam injection system, and then water was removed by freeze-drying.

(Comparative Example 1)

To 2 kg of low-denatured defatted soybean flakes (NSI90), 12 volumes of 40 ° C hot water was added, and the pH was adjusted to 7.0 with a sodium hydroxide solution. Using a homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), this soybean dispersion was stirred at 5000 rpm for 1 hour to extract proteins, and the okara components were removed by a centrifuge (1500 G, 10 minutes) to obtain defatted soymilk. Was. Hydrochloric acid was added to the defatted soy milk to adjust the pH to 4.5, and the protein curd was precipitated and collected by a centrifuge. The protein curd was hydrated and stirred to prepare a curd slurry (DM 9.0%), and the pH was adjusted to 8.8 with a sodium hydroxide solution. To the obtained soybean protein solution, "Pioprase SP-15FG" (produced by Nagase ChemteX Corporation) was added as a proteolytic enzyme at an EZS ratio of 1.8%, followed by hydrolysis at 50 ° C for 4 hours. (15% TCA solubility, 60%). To the soybean protein hydrolyzed solution after the enzymatic reaction, add tenoic acid to adjust the pH to 4.5, then centrifuge (1500 G, 15 minutes) to contain undegraded products. The insoluble matter was separated and removed. The obtained centrifugal supernatant was sterilized at 140 ° C for 10 seconds using a continuous direct heat sterilization apparatus of a steam injection method, and then water was removed by freeze-drying.

(Comparative Example 2)

 Separated soy protein (Fuji Oil Co., Ltd., “New Fuji Pro R”) was used as a 9% solution of pH 7.0, and “Alcalase” (produced by Novozymes Japan Ltd.) was used as a proteolytic enzyme at a 0.05% EZS ratio. The mixture was hydrolyzed for 4 hours at 50 ° C (15% TCA solubility, 30%). The enzyme-reacted soybean protein hydrolyzate was deactivated at 140 ° C for 10 seconds using a steam injection continuous direct heat sterilizer, and then spray-dried with a spray dryer.

 (Comparative Example 3)

 After preparing an 8% solution of isolated soybean protein (“New Fuji Pro R” manufactured by Fuji Oil Co., Ltd.), the pH was adjusted to 8.8. After keeping the prepared solution at 55 ° C for 20 minutes, add “Biooprase SP-15FG” (manufactured by Nagase ChemteX Corporation) as a proteolytic enzyme at an E / S ratio of 2.0% to 55 ° C. Hydrolysis was performed for C3 hours (15% TCA solubility, 82%). Cyanic acid was added to the soybean protein hydrolyzed solution after the enzyme reaction to adjust the pH to 4.5, and then centrifuged (1500 G, 15 minutes) to separate and remove insolubles including undegraded products. The obtained centrifugal supernatant was sterilized at 140 ° C for 10 seconds using a continuous direct heat sterilization apparatus of a steam injection method, and then lyophilized to remove water.

<Evaluation of flavor>

 The dry powders prepared in Examples 1, 2, and 3 and Comparative Examples 1, 2, and 3 were dissolved in water so that a 5% solution was obtained, and the flavor was compared. Bad odors such as unpleasant smell and bitterness and sticking to the tongue were reduced, and the flavor was very good.

Claims

The scope of the claims  [1] A method for producing a soybean protein hydrolyzate by extracting protein from concentrated soybean protein and hydrolyzing the obtained soybean protein extract without going through an acid precipitation step.  [2] The method for producing a soybean protein hydrolyzate according to claim 1, wherein the soybean protein extract before hydrolysis is heat-sterilized.  [3] The method for producing a soybean protein hydrolyzate according to claim 1, wherein the protein is extracted by a countercurrent extraction method. [4] A soybean protein hydrolyzate obtained by extracting and hydrolyzing protein from concentrated soybean protein by countercurrent extraction.  5. The hydrolyzate of soybean protein according to claim 4, wherein the crude protein content per dry solid content is 80% by weight or more.