Method for purifying rapeseed protein

Abstract

The present invention provides: a method for purifying a rapeseed protein, the method comprising a step for washing a rapeseed-protein-containing aqueous solution with salt water; and a rapeseed protein or the like having a total polyphenol content of 0.5 wt% or less.

Description

Method for purifying rapeseed protein

[0001] The present invention relates to a method for purifying rapeseed protein.

[0002] In recent years, there has been an increasing demand for plant protein-containing foods processed using plant proteins such as soy protein. These plant protein-containing foods are required to have a texture similar to meat as meat substitute foods.

[0003] For example, in vegetable protein-containing foods, egg white, methylcellulose, and the like are used as binders to impart a texture similar to that of meat (Patent Document 1, Patent Document 2, etc.). However, due to trends such as vegetarianism and clean labeling, there is a demand for alternative materials to egg white, methylcellulose, and the like.

[0004] Against this background, a formulation for producing a plant protein-containing food, which contains a high molecular weight rapeseed protein and transglutaminase, has been disclosed that can be used as an additional ingredient in the production of a plant protein-containing food to impart a suitable hardness to the food before molding, imparting manufacturing suitability for a wide range of applications, and also imparting excellent hardness, smoothness, fluffiness, etc. to the food after heating or baking (Patent Document 3). However, plant protein-containing foods produced using rapeseed protein have room for further improvement in terms of the bitterness and astringency inherent in the rapeseed protein.

[0005] Conventionally, rapeseed protein has been produced by, for example, extraction using salt water. In this method, rapeseed oil cake (rapeseed meal) is dissolved in salt water to extract the protein into a liquid phase, followed by membrane separation and drying processes to produce rapeseed protein (Non-Patent Document 1). Alternatively, rapeseed protein may be produced by washing the salt-dissolved protein with water (Non-Patent Document 2). However, neither of these methods removes the bitterness and other impurities inherent in rapeseed protein. Furthermore, a method has been disclosed in which canola protein is extracted with a salt solution, membrane-separated, diluted with cold water, and then protein particles are formed, allowing the protein micelles to precipitate and then dried (Patent Document 4). However, this method also fails to remove the bitter components and other impurities inherent in rapeseed protein, and furthermore, the protein recovery rate is low.

[0006] JP 2013-9617 A JP 2009-268378 A International Publication No. 2023 / 054548 JP 2007-508001 A

[0007] U.S. GRAS application documents (GRAS Notice No. 327) U.S. GRAS application documents (GRAS Notice No. 683)

[0008] An object of the present invention is to provide a method for purifying rapeseed protein that reduces the bitterness, astringency, and other properties inherent in rapeseed protein, and to provide rapeseed protein and the like in which the bitterness, astringency, and other properties have been reduced.

[0009] As a result of intensive research into the above-mentioned problems, the present inventors have found that the bitterness, astringency, and other tastes inherent in rapeseed protein can be reduced by washing a rapeseed protein-containing solution with salt water, and have carried out further research based on this finding, thereby completing the present invention.

[0010] [1] A method for purifying a rapeseed protein, comprising the step of washing an aqueous solution containing the rapeseed protein with salt water. [2] The method according to [1] above, wherein the salt concentration in the salt water is 0.01% by weight to 10% by weight. [3] The method according to [1] or [2] above, wherein the step of washing with salt water is a step of subjecting the rapeseed protein to ultrafiltration using salt water. [4] The method according to [3] above, wherein the nominal molecular weight cut-off of the ultrafiltration membrane used for ultrafiltration is 10,000 to 2,000,000. [5] The method according to any of [1] to [4] above, comprising the step of desalting the aqueous solution obtained after the step of washing the aqueous solution containing the rapeseed protein with salt water. [6] The method according to any of [1] to [5] above, further comprising the step of contacting the aqueous solution containing the rapeseed protein with activated carbon. [7] The method according to [6] above, wherein the pH of the aqueous solution containing the rapeseed protein is adjusted to 5 to 11 and the aqueous solution is contacted with activated carbon. [8] The purification method according to any one of [1] to [7] above, wherein the rapeseed protein is a high molecular weight rapeseed protein. [9] The purification method according to any one of [1] to [8] above, wherein the total content of sinapine and sinapic acid in the rapeseed protein is reduced.

[10] The purification method according to any one of [1] to [7] above, wherein the content of rapeseed napin in the rapeseed protein is reduced.

[11] A method for producing a rapeseed protein having reduced bitterness and astringency, comprising the step of washing an aqueous solution containing rapeseed protein with brine.

[12] The production method according to

[11] above, wherein the salt concentration in the brine is 0.01% by weight to 10% by weight.

[13] The production method according to

[11] or

[12] above, wherein the step of washing with brine is a step of subjecting the rapeseed protein to ultrafiltration using brine.

[14] The production method according to

[13] above, wherein the nominal molecular weight cutoff of the ultrafiltration membrane used for ultrafiltration is 10,000 to 2,000,000.

[15] The production method according to any one of

[11] to

[14] above, which comprises a step of desalting the obtained aqueous solution after a step of washing the rapeseed protein-containing aqueous solution with salt water.

[16] The production method according to any one of

[11] to

[15] above, which further comprises a step of contacting the rapeseed protein-containing aqueous solution with activated carbon.

[17] The production method according to

[16] above, wherein the pH of the rapeseed protein-containing aqueous solution is adjusted to 5 to 11 and the aqueous solution is contacted with activated carbon.

[18] The production method according to any one of

[11] to

[17] above, wherein the rapeseed protein is a high molecular weight rapeseed protein.

[19] The production method according to any one of

[11] to

[18] above, wherein the total content of sinapine and sinapic acid in the rapeseed protein is reduced.

[20] The production method according to any one of

[11] to

[17] above, wherein the content of rapeseed napin in the rapeseed protein is reduced.

[21] A rapeseed protein having a total polyphenol content of 0.5% by weight or less.

[22] A rapeseed protein having a tannic acid content of 0.5% by weight or less.

[23] A rapeseed protein having a total content of sinapine and sinapic acid of 0.5% by weight or less.

[24] A rapeseed protein having a rapeseed napin content of 0.1% by weight or less.

[25] The rapeseed protein according to any one of

[21] to

[24] above, wherein the rapeseed protein is a high molecular weight rapeseed protein.

[0011] The present invention provides a method for purifying rapeseed protein that reduces the bitterness, astringency, and other properties inherent in rapeseed protein, and rapeseed protein and the like with reduced bitterness, astringency, and other properties.

[0012] FIG. 1 shows the results of size exclusion chromatography performed in Analysis Example 2. The vertical axis represents absorbance (absorbance units: mAU), and the horizontal axis represents retention time (minutes). "Before activated carbon treatment" represents the first filtrate obtained in Example 3, and "after activated carbon treatment" represents the second filtrate obtained in Example 3. The peak detected at a retention time of 8 minutes is the peak of rapeseed cruciferin, the target protein; the peak detected at a retention time of 13 minutes is the peak of rapeseed napin; and the peaks detected at retention times of 16 to 22 minutes are peaks of low-molecular-weight compounds including sinapine and sinapic acid. FIG. 2 shows the results of size exclusion chromatography performed in Analysis Example 3. The vertical axis represents the ratio of the "rapeseed cruciferin amount" to the "rapeseed cruciferin amount + rapeseed napin amount" (cruciferin amount / (cruciferin amount + napin amount)), and the horizontal axis represents the pH when each first filtrate was stirred with activated carbon.

[0013] 1. Method for purifying rapeseed protein The present invention provides a method for purifying rapeseed protein (hereinafter sometimes referred to as the "purification method of the present invention"), which includes a step of washing an aqueous solution containing rapeseed protein with salt water (hereinafter sometimes referred to as "step 1").

[0014] Rapeseed seed storage proteins (hereinafter sometimes referred to as "rapeseed proteins") extracted and produced from rapeseed seeds are known to contain two main components, one of which is rapeseed globulin (rapeseed cruciferin), which accounts for 60%, and the other is rapeseed albumin (rapeseed napin), which accounts for 20% (Plant's, 5(3), p. 36 (2016), U.S. Patent No. 10,383,345, etc.). The rapeseed proteins used in the purification method of the present invention are broadly classified into high molecular weight rapeseed proteins and low molecular weight rapeseed proteins based on differences in the contents of these main components, but high molecular weight rapeseed proteins, low molecular weight rapeseed proteins, and mixtures of these in any ratio are all included in the rapeseed proteins used in the purification method of the present invention.

[0015] In this specification, "high molecular weight rapeseed protein" refers to a rapeseed protein having a weight-average molecular weight of 15,000 or more, preferably rapeseed globulin. Rapeseed globulin is a complex of multiple subunits with an average molecular weight of approximately 48,000 to 54,000, each of which consists of two polypeptide chains, an alpha chain and a beta chain, of which multiple isoforms exist (The Journal of Biological Chemistry, 265(5), p. 2720 (1990), The Journal of Biological Chemistry, 288(4), p. 2238 (2013), etc.). Rapeseed globulin changes its form depending on the surrounding environment. For example, under high ionic strength, it exists as a 300 kDa 12S rapeseed globulin having six subunits, but under low ionic strength, it reversibly dissociates and exists as a 150 kDa 7S rapeseed globulin having three subunits (12S and 7S represent sedimentation coefficients) (U.S. Patent Publication No. 2019 / 0307149, etc.). That is, rapeseed globulin exists as either 7S rapeseed globulin or 12S rapeseed globulin, or a mixture thereof. In addition, for example, the amino acid sequences of some of the above subunits are disclosed in JP 2013-226094 A, etc., and cDNA is disclosed in The Journal of Biological Chemistry, 265 (5), etc. The high molecular weight rapeseed protein used in the present invention is more preferably a mixture of 7S rapeseed globulin and 12S rapeseed globulin.

[0016] In this specification, the low molecular weight rapeseed protein means a rapeseed protein having a weight average molecular weight of less than 15,000, and preferably includes rapeseed albumin.

[0017] The rapeseed protein can be separated from rapeseed seeds by, for example, the methods described in Lipid Technology, 27(5), p. 112 (2015), Food Science and Technology, 64(1), p. 308 (2015), Plants, 5(3), p. 36 (2016), U.S. Patent No. 10,383,345, or methods similar thereto. The rapeseed protein may also be obtained by fermentation. The rapeseed protein may be a commercially available product, and specific examples include "Puratein (registered trademark) G" (Merit Functional Foods Corporation), "Puratein (registered trademark) HS" (Merit Functional Foods Corporation), and "CanolaPRO (registered trademark)" (DSM), but are not limited to these.

[0018] The water used in the rapeseed protein-containing aqueous solution is preferably purified water, distilled water, deionized water, tap water, or other water suitable for use in food production.

[0019] The salt water means a salt solution, and the salt concentration in the salt water is usually 0.01% to 10% by weight, preferably 0.03% to 5% by weight, and more preferably 0.1% to 3% by weight.

[0020] In this specification, the "step of washing with salt water" is not particularly limited as long as the object of the present invention is achieved, but is preferably a step of subjecting the product to ultrafiltration using salt water. Ultrafiltration is carried out using an ultrafiltration membrane, and commercially available ultrafiltration membranes can be suitably used, for example, "Microza AHP-1013D" (manufactured by Asahi Kasei Corporation). The nominal molecular weight cutoff of the ultrafiltration membrane is preferably 10,000 to 2,000,000, more preferably 15,000 to 150,000, and even more preferably 30,000 to 100,000. In ultrafiltration, for example, 100 parts by weight of an aqueous solution containing rapeseed protein is concentrated usually to 10 to 80 parts by weight, preferably to 20 to 70 parts by weight, and more preferably to 30 to 60 parts by weight, and then brine is usually replenished in an amount approximately equal to the amount of the aqueous solution obtained by concentration, and the solution is concentrated again. This process is usually repeated multiple times, preferably 2 to 5 times, and more preferably 3 to 4 times.

[0021] In one embodiment, the purification method of the present invention further comprises, after step 1, a step of desalting the aqueous solution obtained (hereinafter, sometimes referred to as "step 2").

[0022] In the present specification, the method for carrying out step 2 is not particularly limited as long as the object of the present invention is achieved, but a method involving ultrafiltration using water is preferred. The ultrafiltration membrane used in the ultrafiltration in step 2 can be the same as the ultrafiltration membrane used in the ultrafiltration in step 1 described above. Furthermore, in the ultrafiltration in step 2, for example, 100 parts by weight of an aqueous solution containing rapeseed protein is concentrated typically to 5 to 50 parts by weight, preferably 8 to 40 parts by weight, and more preferably 10 to 25 parts by weight, and then water is replenished in an amount approximately equal to the amount of the aqueous solution obtained by the usual concentration, and the process of concentrating again is repeated typically until the sodium concentration reaches 0.1% by weight or less, preferably 0.08% by weight or less, and more preferably 0.05% by weight or less.

[0023] Furthermore, by using an ultrafiltration membrane with a nominal molecular weight cutoff of 10,000 to 2,000,000 in step 1 and / or step 2, when the rapeseed protein is a mixture of high molecular weight rapeseed protein and low molecular weight rapeseed protein, it is possible to separate and remove the low molecular weight rapeseed protein as well, and obtain rapeseed protein that is rich in high molecular weight rapeseed protein, rapeseed protein that is almost entirely high molecular weight rapeseed protein, rapeseed protein that is substantially entirely high molecular weight rapeseed protein, rapeseed protein that is entirely high molecular weight rapeseed protein, etc. That is, in one aspect, the purification method of the present invention is a method for purifying high molecular weight rapeseed protein, which includes a step of washing an aqueous solution containing rapeseed protein with salt water.

[0024] In one embodiment, the purification method of the present invention further comprises a step of contacting the rapeseed protein-containing aqueous solution with activated carbon (hereinafter, sometimes referred to as "step 3").

[0025] Activated carbon can be obtained by subjecting raw materials such as wood flour, coconut shells, coal, and petroleum pitch to activation with chemicals, gas activation, or the like. Examples of chemical activation include zinc chloride activation and phosphoric acid activation, while examples of gas activation include steam activation, hydrogen chloride activation, carbon dioxide activation, and oxygen activation, with zinc chloride activation and steam activation being preferred. Activated carbon is usually commercially available, and more specific examples include DARCO (registered trademark) KB-G (Cabot Japan Co., Ltd.), PL-CPS2 (zinc chloride-activated carbon; Dainen Co., Ltd.), and Shirasagi AW (steam-activated carbon; Osaka Gas Chemicals Co., Ltd.).

[0026] In the present specification, the method for carrying out step 3 is not particularly limited as long as the object of the present invention is achieved. However, a preferred method is to add, for example, an alkaline aqueous solution to an aqueous solution containing rapeseed protein to adjust the pH of the aqueous solution to approximately neutral or alkaline, for example, pH 5 to 11, preferably pH 6 to 10.5, more preferably pH 7 to 10, even more preferably pH 7.5 to 9.5, and even more preferably pH 8 to 9.5, before contacting the aqueous solution with activated carbon. Examples of alkaline aqueous solutions include aqueous sodium hydroxide, aqueous potassium hydroxide, aqueous barium hydroxide, and aqueous ammonium. Of these, aqueous sodium hydroxide, aqueous potassium hydroxide, and aqueous ammonium are preferred, and aqueous sodium hydroxide is more preferred. Specific examples of methods for contacting an aqueous solution containing rapeseed protein with activated carbon include preparing an aqueous solution containing rapeseed protein, adding activated carbon to the aqueous solution, and stirring the mixture. The timing of carrying out step 3 is also not particularly limited as long as the object of the present invention is achieved. However, it is preferably before step 1 or between steps 1 and 2, and more preferably before step 1.

[0027] The purification method of the present invention may include one or more other optional steps used in protein purification, in addition to steps 1, 2, and 3. The other steps can be carried out before step 1, simultaneously with step 1, between steps 1 and 2, simultaneously with step 2, or after step 2, as appropriate. Examples of the other steps include filtration, filter pressing, extraction, washing, centrifugation, decantation, drying, concentration, various types of chromatography, and the like. More specific examples include filter pressing carried out before step 1, microfiltration carried out before step 1, and drying carried out after step 2.

[0028] The purification method of the present invention makes it possible to obtain rapeseed protein with reduced bitterness (bitterness derived from rapeseed), astringent taste (astringent taste derived from rapeseed), etc. Bitterness, astringent taste, etc. can be evaluated by sensory evaluation by panelists skilled in evaluation, as shown in the test examples described below.

[0029] Furthermore, the purification method of the present invention can produce rapeseed protein with reduced tannic acid and total polyphenol contents. Specifically, rapeseed protein having a tannic acid content of 0.5% by weight or less, rapeseed protein having a total polyphenol content of 0.5% by weight or less, etc., more preferably rapeseed protein having a tannic acid content of 0.45% by weight or less, rapeseed protein having a total polyphenol content of 0.45% by weight or less, even more preferably rapeseed protein having a tannic acid content of 0.4% by weight or less, rapeseed protein having a total polyphenol content of 0.4% by weight or less, etc., even more preferably rapeseed protein having a tannic acid content of 0.35% by weight or less, rapeseed protein having a total polyphenol content of 0.35% by weight or less, etc. The total polyphenol content and tannic acid content can be measured by methods known per se, for example, the method described in "Science and Technology Research, 2012, Vol. 1, No. 2, pp. 139-144," or the method described in the analytical examples below that references this method.

[0030] Here, polyphenol is a general term for plant components having a phenolic hydroxy group in the molecule, and examples thereof include tannic acid, curcumin, quercetin, anthocyanin, catechin, rutin, isoflavone, cacao polyphenol, shogaol, and chlorogenic acid.

[0031] Furthermore, the purification method of the present invention can produce rapeseed proteins having a reduced total content of sinapine and sinapic acid. Specifically, rapeseed proteins having a total content of sinapine and sinapic acid of 0.5 wt% or less, more preferably a rapeseed protein having a total content of sinapine and sinapic acid of 0.45 wt% or less, even more preferably a rapeseed protein having a total content of sinapine and sinapic acid of 0.4 wt% or less, and even more preferably a rapeseed protein having a total content of sinapine and sinapic acid of 0.35 wt% or less. The contents of sinapine and sinapic acid can be measured by methods known per se, for example, in accordance with the method shown in the Reference Examples described below.

[0032] Furthermore, one embodiment of the purification method of the present invention can obtain a rapeseed protein having a reduced rapeseed napin content. Specifically, it is possible to obtain a rapeseed protein having a weight ratio of 0.3 or less between the rapeseed napin content and the total content of rapeseed cruciferin and rapeseed napin ("napin amount / (cruciferin amount+napin amount)"), more preferably a rapeseed protein having a weight ratio of 0.1 or less between napin amount / (cruciferin amount+napin amount), even more preferably a rapeseed protein having a weight ratio of 0.01 or less between napin amount / (cruciferin amount+napin amount), and even more preferably a rapeseed protein having a weight ratio of 0.001 or less between napin amount / (cruciferin amount+napin amount). Furthermore, it is possible to obtain rapeseed protein etc. having a rapeseed napin content of 0.1 wt % or less, more preferably rapeseed protein etc. having a rapeseed napin content of 0.01 wt % or less, even more preferably rapeseed protein etc. having a rapeseed napin content of 0.001 wt % or less, and even more preferably rapeseed protein etc. having a rapeseed napin content of 0.0001 wt % or less. The amounts of rapeseed cruciferin and rapeseed napin can be measured by methods known per se, for example, in accordance with the methods shown in the analytical examples described below.

[0033] Furthermore, by using the rapeseed protein obtained by the purification method of the present invention in the production of a plant protein-containing food, it is possible to obtain a plant protein-containing food with reduced bitterness, astringency, etc. Furthermore, the plant protein-containing food produced using the rapeseed protein obtained by the purification method of the present invention is also preferable in terms of overall hardness, meaty texture, etc., with strong overall hardness, meaty texture, etc. and improved bitterness, astringency, etc. The overall hardness, meaty texture, etc. can also be evaluated by sensory evaluation by panelists skilled in evaluation, as shown in the test examples described below.

[0034] In a plant protein-containing food produced using rapeseed protein obtained by the purification method of the present invention, the plant protein can be contained in the food as a plant protein-containing composition. The plant protein-containing composition is not particularly limited as long as it contains a protein derived from a plant, and may be purified plant protein itself or may contain other components derived from the plant. For example, it includes plants whose protein content has been increased by processing. Specific examples of plant proteins include soy protein, wheat protein, pea protein, mung bean protein, fava bean protein, edamame protein, chia seed protein, corn protein, rice protein, buckwheat protein, sweet potato protein, asparagus protein, broccoli protein, avocado protein, oat protein, and almond protein, and one or more of these can be used in combination. Soy protein is preferred as the plant protein.

[0035] Plant protein-containing foods produced using rapeseed protein obtained by the purification method of the present invention are not particularly limited, and examples include meat substitute foods. In this specification, meat substitute foods refer to foods that normally contain meat as at least a portion of the ingredients, but in which a meat substitute material such as plant protein is used instead of meat. More specifically, meat substitute foods include minced meat substitutes (minced meat-like foods), such as sausage substitutes (sausage-like foods), pate substitutes (pate-like foods) including hamburger substitutes (hamburger-like foods), ham substitutes (ham-like foods), and nugget substitutes (nugget-like foods). Among these, sausage, pate, or nugget substitutes are preferred, and sausage or pate substitutes are even more preferred. In addition to the above-mentioned meat substitute foods, examples of plant protein-containing foods produced using rapeseed protein obtained by the purification method of the present invention include fish substitute foods that contain fish meat as at least a part of the ingredients, using a fish substitute material such as plant protein instead of fish meat (fish sausage substitute foods (fish sausage-like foods), kamaboko substitute foods (kamaboko-like foods), chikuwa substitute foods (chikuwa-like foods), satsumaage substitute foods (satsumaage-like foods), etc.).

[0036] In vegetable protein-containing foods produced using the rapeseed protein obtained by the purification method of the present invention, the rapeseed protein can be used, for example, as a binder. Binders are used as binding materials to prevent food ingredients from separating or crumbling, and the rapeseed protein obtained by the purification method of the present invention is preferably used as a binder in place of egg white, methylcellulose, etc. in the production of vegetable protein-containing foods.

[0037] In a plant protein-containing food produced using the rapeseed protein obtained by the purification method of the present invention, transglutaminase (hereinafter sometimes referred to as "TG") can be used in combination. By using TG in combination with rapeseed protein, a more excellent binding effect can be obtained.

[0038] TG is an enzyme that catalyzes an acyl transfer reaction in which a glutamine residue in a protein or peptide serves as a donor and a lysine residue serves as an acceptor. TGs are known to be derived from a variety of sources, including mammals, fish, and microorganisms. The transglutaminase used in the present invention is not particularly limited in origin as long as it has the above-described activity, and transglutaminases of any origin can be used. Furthermore, recombinant enzymes may also be used. The transglutaminase used in the present invention may be a commercially available product, and specific examples include microbial transglutaminases commercially available under the trade names "Activa (registered trademark) [Ajinomoto Co., Inc.]" and "KS-CT [Ajinomoto Co., Inc.]."

[0039] In this specification, the activity unit of transglutaminase is measured and defined as follows: Transglutaminase is allowed to act in a reaction system using benzyloxycarbonyl-L-glutamylglycine and hydroxylamine as substrates in a Tris buffer solution at 37°C and pH 6.0, and the resulting hydroxamic acid is allowed to form an iron complex in the presence of trichloroacetic acid. The absorbance at 525 nm is then measured, and the amount of hydroxamic acid is determined using a calibration curve. One unit (1 U) is defined as the amount of enzyme that produces 1 μmole of hydroxamic acid per minute (see Japanese Patent Laid-Open No. 27471 / 1989).

[0040] Plant protein-containing foods produced using rapeseed protein obtained by the purification method of the present invention can be produced by methods known per se, for example, the method described in WO 2023 / 054548 or a method similar thereto.

[0041] 2. Method for Producing Rapeseed Protein The present invention also provides a method for producing rapeseed protein with reduced bitterness and astringency, which comprises the step of washing an aqueous solution containing rapeseed protein with salt water (hereinafter, sometimes referred to as the "production method of the present invention").

[0042] The "rapeseed protein," "water," "salt water," and "step of washing with salt water" are as explained above in the purification method of the present invention.

[0043] In addition to the step of washing the rapeseed protein-containing aqueous solution with salt water, the production method of the present invention may include steps similar to the steps other than step 1 in the purification method of the present invention described above.

[0044] The production method of the present invention may further include one or more of any other steps used in the production of proteins, including powdering the purified rapeseed protein after drying.

[0045] The production method of the present invention makes it possible to obtain rapeseed protein with reduced bitterness (bitterness derived from rapeseed), astringent taste (astringent taste derived from rapeseed), etc. Bitterness, astringent taste, etc. can be evaluated by sensory evaluation by panelists skilled in evaluation, as shown in the test examples described below.

[0046] Furthermore, the production method of the present invention can produce rapeseed protein with reduced tannic acid and total polyphenol contents. The "rapeseed protein with reduced tannic acid and total polyphenol contents" is the same as the "rapeseed protein with reduced tannic acid and total polyphenol contents" described above in connection with the purification method of the present invention.

[0047] Furthermore, the production method of the present invention can provide a rapeseed protein having a reduced total content of sinapine and sinapic acid. The "rapeseed protein having a reduced total content of sinapine and sinapic acid" is the same as the "rapeseed protein having a reduced total content of sinapine and sinapic acid" described above in connection with the purification method of the present invention.

[0048] Furthermore, in one embodiment of the production method of the present invention, it is possible to obtain rapeseed protein having a reduced rapeseed napin content. The "rapeseed protein having a reduced rapeseed napin content" is the same as the "rapeseed protein having a reduced rapeseed napin content" described above in connection with the purification method of the present invention.

[0049] Furthermore, by using the rapeseed protein obtained by the production method of the present invention in the production of a plant protein-containing food, it is possible to obtain a plant protein-containing food with reduced bitterness, astringency, etc. Furthermore, the plant protein-containing food produced using the rapeseed protein obtained by the production method of the present invention is also preferable in terms of overall hardness, meaty texture, etc., with strong overall hardness, meaty texture, etc. and improved bitterness, astringency, etc. The overall hardness, meaty texture, etc. can also be evaluated by sensory evaluation by panelists skilled in evaluation, as shown in the test examples described below.

[0050] The "plant protein-containing food produced using rapeseed protein obtained by the production method of the present invention" is the same as the "plant protein-containing food produced using rapeseed protein obtained by the purification method of the present invention" described above in relation to the purification method of the present invention.

[0051] 3. Rapeseed Protein The present invention also provides a rapeseed protein having a total polyphenol content of 0.5% by weight or less (hereinafter sometimes referred to as "rapeseed protein 1 of the present invention"), a rapeseed protein having a tannic acid content of 0.5% by weight or less (hereinafter sometimes referred to as "rapeseed protein 2 of the present invention"), a rapeseed protein having a total content of sinapine and sinapic acid of 0.5% by weight or less (hereinafter sometimes referred to as "rapeseed protein 3 of the present invention"), and a rapeseed protein having a rapeseed napin content of 0.01% by weight or less (hereinafter sometimes referred to as "rapeseed protein 4 of the present invention").

[0052] The "rapeseed protein," "polyphenols," "rapeseed napin," "tannic acid content," "total polyphenol content," "total content of sinapine and sinapic acid," and "rapeseed napin content," including the preferred ranges of each content, are as described above in the purification method of the present invention.

[0053] In one embodiment, the rapeseed protein is a high molecular weight rapeseed protein.

[0054] Rapeseed protein 1 of the present invention, rapeseed protein 2 of the present invention, and rapeseed protein 3 of the present invention can be produced by the purification method of the present invention and / or the production method of the present invention. Furthermore, rapeseed protein 4 of the present invention can be produced by one embodiment of the purification method of the present invention and / or one embodiment of the production method of the present invention.

[0055] The rapeseed protein 1 of the present invention, the rapeseed protein 2 of the present invention, and the rapeseed protein 3 of the present invention have reduced bitterness, astringency, etc., and the plant protein-containing foods produced using the rapeseed protein 1 of the present invention, the rapeseed protein 2 of the present invention, and the rapeseed protein 3 of the present invention are each preferable in terms of overall hardness, meaty texture, etc., with strong overall hardness, meaty texture, etc. and improved bitterness, astringency, etc. Bitterness, astringency, overall hardness, meaty texture, etc. can be evaluated by sensory evaluation by panelists skilled in evaluation, as shown in the test examples described below.

[0056] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples in any way.

[0057] Unless otherwise specified, the raw materials and products used in the examples are as follows: Rapeseed protein product A (hereinafter also referred to as "product A"): "Puratein G" (Merit Functional Foods Corporation) Rapeseed protein product B (hereinafter also referred to as "product B"): "CanolaPRO" (DSM) Methylcellulose: "Metolose" (Shin-Etsu Chemical Co., Ltd.)

[0058] ・TG: "KS-CT" (Ajinomoto Co., Inc.) ・Granular protein: "New Fujinic" (Fuji Oil Co., Ltd.) ・Fibrous protein: "Apex" (Fuji Oil Co., Ltd.) ・Vegetable oil: "Canola Oil" (J-Oil Mills Co., Ltd.) ・Solid vegetable oil: "Fashier" (J-Oil Mills Co., Ltd.) ・Garlic powder: "Garlic Powder" (GS Food Co., Ltd.) ・Black pepper: "Black Pepper" (S&B Foods Co., Ltd.) ・Nutmeg: "Nutmeg" (House Foods Corporation)

[0059] Example 1 (Separation of High Molecular Weight Rapeseed Protein 1) 900 g of rapeseed meal (rapeseed meal (J-Oil Mills Co., Ltd.)) and 7,200 g of 1 wt % saline solution were placed in a 10 L stainless steel container and stirred for 2 hours at 25°C using a stirring blade. The resulting slurry was centrifuged at 9,000 rpm for 15 minutes. Filter paper (circular quantitative filter paper 5A, Advantec Toyo Co., Ltd.) was placed in a Buchner funnel and pre-coated with diatomaceous earth (Radiolite #300, Showa Chemical Industry Co., Ltd.) suspended in water. The supernatant obtained by centrifugation was further filtered to obtain 6,100 g of first filtrate. Next, the rapeseed meal that had settled after centrifugation was added to 3,600 g of 1 wt % saline solution and stirred for 5 minutes using a stirring blade. The resulting slurry was then centrifuged at 9,000 rpm for 15 minutes. A filter paper was placed on a Buchner funnel and precoated with diatomaceous earth suspended in water. The supernatant obtained by centrifugation was further filtered, yielding 3,600 g of No. 2 filtrate. The No. 1 and No. 2 filtrates were placed in a 10 L stainless steel container and microfiltered using a 0.45 μm pore size microfiltration membrane (Microza ULP-143, Asahi Kasei Corporation), yielding 9,670 g of No. 3 filtrate. Concentration of the No. 3 filtrate was initiated using an ultrafiltration membrane (Microza AHP-1013D, Asahi Kasei Corporation) with a nominal molecular weight cutoff of 50,000. After concentrating the circulating liquid to 4,000 g, a saline wash operation was performed three times, in which 4,000 g of 1 wt % saline was added to the circulating liquid and the liquid was again concentrated to 4,000 g. The circulating liquid was then concentrated to 500 g, and 500 g of water was added and the mixture was concentrated again to 500 g. This desalination procedure was repeated until the sodium concentration reached 0.05 wt%. After concentration, the wash liquid and the remaining liquid in the membrane were collected and mixed with the concentrate, yielding 627 g of concentrate. The concentrate was dried in a freeze dryer (Genesis 25 EL, SP Industries, Inc.) to yield 43 g of rapeseed meal extract (rapeseed protein product 1) powder.

[0060] Example 2 (Separation of High Molecular Weight Rapeseed Protein 2) 300 g of Product A and 6,060 g of 3 wt % saline solution were placed in a 10 L stainless steel container and stirred at 25°C for 1 hour using a stirring blade. The mixture was filtered using a Buchner funnel with filter paper (Circular Quantitative Filter Paper 5A, Advantec Toyo Co., Ltd.), yielding 6,095 g of No. 1 filtrate. The No. 1 filtrate was placed in a 10 L stainless steel container and filtered using a microfiltration membrane with a pore size of 0.45 μm (Microza ULP-143, Asahi Kasei Corporation), yielding 5,419 g of No. 2 filtrate. The No. 2 filtrate was placed in a 10 L stainless steel container and concentrated using an ultrafiltration membrane with a nominal molecular weight cutoff of 50,000 (Microza AHP-1013D, Asahi Kasei Corporation). The filtrate was concentrated to 1,000 g, and then 1,000 g of 1 wt% saline was added and concentrated again to 1,000 g, three times. Next, the circulating liquid side was concentrated to 500 g, and then 500 g of water was added and concentrated again to 500 g. This desalination operation was repeated until the sodium concentration reached 0.05 wt%. Finally, after concentration to 350 g, the washing liquid and the remaining liquid in the membrane were collected and mixed with the concentrate, and 463 g of concentrate was finally obtained. The concentrate was dried in a freeze dryer (Genesis 25 EL, SP Industries, Inc.), and 108 g of rapeseed protein product 2 powder was obtained.

[0061] Analysis Example 1 (Analysis of Tannic Acid Amount and Total Polyphenol Amount) Using powders of Product A and Product B (neither of which was washed with salt water) as well as powder of Product A (rapeseed protein product 2) obtained by washing with salt water and drying in the same manner as in Example 2 as samples, the amounts of tannic acid and total polyphenols in each sample were quantified with reference to the method described in "Science and Technology Research, 2012, Vol. 1, No. 2, pp. 139-144."

[0062] Specifically, in the case of tannic acid, 0.1 g of the sample was taken and 100 mL of hot water was added to extract the components. The test solution was prepared by filtering through filter paper to separate the insoluble solids. 5 mL of the test solution and 5 mL of the tannic acid standard solution were taken, and 5 mL of Folin's reagent and 5 mL of 10% aqueous sodium carbonate solution were added, followed by standing at room temperature for 1 hour. After centrifuging to remove the precipitate, the absorbance was measured at an absorption wavelength of 700 nm using a spectrophotometer, and the quantitative value was calculated from the absorbance of the standard solution.

[0063] Specifically, for total polyphenols, 0.1 g of sample was extracted with 100 mL of hot water. Extraction solvents such as 70%-90% (v / v) aqueous methanol, acetone, 80% (v / v) aqueous ethanol, and 0.5% (v / v) aqueous acetic acid were also available. Test solutions were prepared by filtration through filter paper to separate insoluble solids. 1 mL of the test solution and the polyphenol standard solution (gallic acid standard solution) were each extracted, and 5 mL of 10% (v / v) phenol reagent dilution was added. After thorough stirring, 4 mL of 7.5% (w / v) aqueous sodium carbonate solution was added within 3-8 minutes. The mixture was again thoroughly stirred and allowed to stand at room temperature for 1 hour. After centrifugation to remove the precipitate, the absorbance was measured at 765 nm using a spectrophotometer, and the quantitative value was calculated from the absorbance of the standard solution. The results are shown in Table 1.

[0064]

[0065] Test Example 1 (Evaluation of Suspension) (Sample Preparation) Each of the powders of Product A and Product B (neither of which was washed with salt water) and the powder of rapeseed protein product 1 obtained in Example 1 was suspended in water to a concentration of 3 wt %.

[0066] (Sensory evaluation) The bitterness and astringency of each of the suspensions obtained above were evaluated by four panelists skilled in evaluation, who rated the results on a three-level scale shown in Table 2 in increments of one point, and the evaluation was conducted by consensus.

[0067]

[0068] The results are shown in Table 3.

[0069]

[0070] As shown in Table 3, in the suspension of rapeseed protein product 1 that had been washed with salt water, both the bitterness and astringency were reduced, and the bitterness was reduced to a level that was barely noticeable.

[0071] Test Example 2 (Evaluation of pate-like food) (Preparation of pate-like food) Pate-like foods were prepared in the blending ratios shown in Table 4 as follows.

[0072]

[0073] The base protein was reconstituted with water using a water reconstitution solution, and then mixed with the enzyme and binder components, and then with the oil and fat components and seasoning components, and the mixture was molded and baked at 180°C to prepare a pate-like food product, which was then flash-frozen, placed in a vacuum pouch, and stored frozen.

[0074] (Breaking Strength Evaluation) The breaking strength of each of the pate-like foods obtained above was examined before and after baking using a texture analyzer (TA) (TA-XT-plus, Stable Microsystems). Specifically, each pate-like food was placed horizontally and broken using a wedge-shaped plunger to measure the stress (g). As a result, the pate-like food prepared using the powder of Product A without salt water washing showed an increase in breaking strength of 534 g before and after baking, while the pate-like food prepared using the powder of rapeseed protein product 1 obtained in Example 1 showed an increase in breaking strength of 681 g before and after baking. Furthermore, the pate-like food prepared without rapeseed protein and the pate-like food prepared using egg white instead of rapeseed protein showed increases in breaking strength of 321 g and 809 g, respectively, before and after baking.

[0075] (Sensory evaluation) The sensory characteristics, bitterness, and astringency of each of the pate-like foods obtained above were evaluated by six panelists skilled in evaluation, who scored the foods on a three-level scale shown in Table 5 in increments of 0.5 points, and the scores obtained by the six panelists were averaged to evaluate the foods.

[0076]

[0077] The average evaluation results by each panelist are shown in Table 6.

[0078]

[0079] As shown in Table 6, the pate-like food prepared using the powder of rapeseed protein product 1 that had been washed with salt water was excellent in terms of overall hardness, meaty texture, bitterness, and astringent taste, with a strong overall hardness and meaty texture and improved bitterness and astringent taste.

[0080] Example 3 (Separation of High Molecular Weight Rapeseed Protein 3; Using Activated Carbon) 500 g of rapeseed meal and 4,000 g of 1 wt % saline solution were placed in a 5 L plastic container and stirred at 50 ° C for 4 hours using a stirring blade. The resulting slurry was centrifuged at 9,000 rpm for 15 minutes. A Buchner funnel was placed on filter paper (Circular Quantitative Filter Paper 5A, Advantec Toyo Co., Ltd.) and pre-coated with diatomaceous earth (Radiolite #300, Showa Chemical Industry Co., Ltd.) suspended in water. The supernatant obtained by centrifugation was further filtered to obtain 2,890 g of No. 1 filtrate. Next, 2,890 g of No. 1 filtrate was added with 1 M aqueous sodium hydroxide solution until the pH reached 9, and then 57.8 g of activated carbon (PL-CPS2, Dainen Co., Ltd.) was added and stirred at 50 ° C for 1 hour. A Buchner funnel was loaded with filter paper, precoated with diatomaceous earth suspended in water, and the resulting mixture was stirred after adding activated carbon. The resulting mixture was filtered, yielding 2,540 g of No. 2 filtrate. The No. 2 filtrate was microfiltered using a 0.45 μm pore size microfiltration membrane (Microza ULP-143, Asahi Kasei Corporation). 500 mL of water was added to wash the microfiltration membrane, yielding 3,180 g of No. 3 filtrate. Concentration of the No. 3 filtrate was initiated using an ultrafiltration membrane (Microza AOP-1013D, Asahi Kasei Corporation) with a nominal molecular weight cutoff of 80,000. After concentrating the circulating liquid to 1,500 g, a saline wash procedure was performed three times: adding 1,500 g of 1 wt. % saline to the circulating liquid and concentrating again to 1,500 g. The circulating liquid was then concentrated to 500 g, and 500 g of water was added and the solution was again concentrated to 500 g. This desalination procedure was repeated until the sodium concentration reached 0.05 wt%. After concentration, the wash liquid and the remaining liquid in the membrane were collected and mixed with the concentrate, yielding 744 g of concentrate. The concentrate was dried in a freeze dryer (Genesis 25 EL, SP Industries, Inc.) to yield 15.5 g of rapeseed meal extract (rapeseed protein product 3) powder.

[0081] Analysis Example 2 (Composition Analysis) Using the first filtrate obtained in Example 3 and the second filtrate obtained in Example 3 as samples, size exclusion chromatography measurements were carried out under the following analysis conditions.

[0082] [Analysis conditions] Detector: UV absorption photometer (measurement wavelength 280 nm) Column: AdvanceBio SEC 300 Å (particle size 2.7 μm, column inner diameter 4.6 mm × length 30 cm) (Agilent Technologies, Inc.) Mobile phase: 0.05 M Tris hydrochloride buffer (pH 7.6), 0.2 M sodium chloride Flow rate: 0.3 mL / min Analysis time: 25 min

[0083] The results are shown in Figure 1.

[0084] As shown in FIG. 1, by contacting an aqueous solution containing rapeseed protein with activated carbon, rapeseed napin and low molecular weight compounds including sinapine and sinapic acid, which exhibit off-flavors such as astringency, were removed.

[0085] Reference Example 1 (Effect of Rapeseed Napin) Rapeseed protein products with different napin contents were produced from the four types of rapeseed shown in Table 7 below using the purification method / production method of the present invention, and pate-like foods were prepared using each of the resulting rapeseed protein products in the same manner as in Test Example 2 (Preparation of pate-like foods). For each of the resulting pate-like foods, the breaking strength after baking was evaluated in the same manner as in Test Example 2 (Evaluation of breaking strength). Each rapeseed protein product was dissolved in 1 wt % saline, and the amounts of rapeseed cruciferin and rapeseed napin were measured by size exclusion chromatography under the analytical conditions described in Analysis Example 2. The ratio of "rapeseed cruciferin amount" to "rapeseed cruciferin amount + rapeseed napin amount" (cruciferin amount / (cruciferin amount + napin amount)) and the ratio of "rapeseed napin amount" to "rapeseed cruciferin amount + rapeseed napin amount" (napin amount / (cruciferin amount + napin amount)) were calculated and shown together in Table 7 below.

[0086] The results are shown in Table 7.

[0087]

[0088] As shown in Table 7, it was confirmed that as the rapeseed napin content in rapeseed protein increased, the breaking strength of the pate-like food gradually decreased, indicating that rapeseed napin has a negative effect on the breaking strength of the pate-like food and that it is desirable to remove rapeseed napin.

[0089] Example 4 (Separation of High Molecular Weight Rapeseed Protein 4; Using Activated Carbon) 70 g of rapeseed meal (canola meal, Cargill Japan) and 700 g of 1 wt% saline solution were placed in a 2 L plastic container and stirred at 50 °C for 2 hours using a stirring blade. The resulting slurry was centrifuged at 9,000 rpm for 15 minutes. A Buchner funnel was placed on filter paper (circular quantitative filter paper 5A, Advantec Toyo Co., Ltd.) and pre-coated with diatomaceous earth (Radiolite #300, Showa Chemical Industry Co., Ltd.) suspended in water. The supernatant obtained by centrifugation was further filtered to obtain 560 g of the first filtrate. Next, 50 g of the first filtrate was placed in five 100 mL beakers, and the pH was adjusted to 3.0, 4.0, 5.9, 7.1, and 8.5 with sodium hydroxide or hydrochloric acid aqueous solution, respectively. To each of the pH-adjusted first filtrates, 2 g of activated carbon (Shirasagi AW, Osaka Gas Chemicals Co., Ltd.) was added, and the mixture was stirred for 1 hour at 25° C. using a magnetic stirrer. After stirring, each of the resulting mixtures was filtered through a 0.45 μm syringe filter to obtain each filtrate.

[0090] Analysis Example 3 (Analysis of rapeseed napin amount) Using each filtrate obtained in Example 4 as a sample, the amounts of rapeseed cruciferin and rapeseed napin were measured by size exclusion chromatography under the analysis conditions described in Analysis Example 2, and the ratio of the "rapeseed cruciferin amount" to the "rapeseed cruciferin amount + rapeseed napin amount" was calculated.

[0091] The results are shown in Figure 2.

[0092] As shown in FIG. 2, rapeseed napin was almost completely removed by contacting an aqueous solution containing rapeseed protein with activated carbon at a pH of 5.9, and rapeseed napin was completely removed by contacting an aqueous solution containing rapeseed protein with activated carbon at a pH of 7.1 or 8.5.

[0093] Reference Example 2 (Purification of Sinapine and Sinapic Acid) 120 mL of the wash solution obtained by concentrating the No. 2 filtrate in Example 2 using an ultrafiltration membrane was placed in 30 mL portions into 50 mL plastic containers, and each portion was dried using a freeze dryer. 1.5 mL of water was added to each dried product, and the mixture was mixed to obtain a centrifugal supernatant. The centrifugal supernatants were combined and injected into HPLC, and sinapine and sinapic acid were separated under the following separation conditions. Next, 30 mL of either 454 mL of the sinapine fraction or 306 mL of the sinapic acid fraction was placed in a 50 mL plastic container, and the entire volume was dried using a freeze dryer. Water was added to each dried product to obtain 10 mL of sinapine fraction solution and 10 mL of sinapic acid fraction solution.

[0094] [Analysis conditions] Column: Inertsil ODS-4V, 5 μm, 10 × 250 mm (GL Sciences Inc.) Guard column: Inertsil ODS-4V, 5 μm, 10 × 50 mm (GL Sciences Inc.) Mobile phase: A: water B: ethanol Flow rate: 3.2 mL / min Detection: UV 325 nm, 210 nm Column temperature: 40°C Injection volume: 200 μL Analysis time: 60 min Gradient (% of B): 0.0 min, 5% 12.0 min, 5% 37.0 min, 40% 47.0 min, 40% 47.1 min, 5% Fractionation time: Sinapic acid 23.80-26.70 min Sinapine 29.40-33.70 min

[0095] Evaluation Example 4 (Effects of Sinapine and Sinapic Acid) (Sample Preparation) Using the powder of Product A, the powder of rapeseed protein product 2 obtained in Example 2, and the sinapine fraction solution and / or sinapic acid fraction solution obtained in Reference Example 2, samples (evaluation solutions) were prepared at the blending ratios (weight ratios) shown in Table 8 below. The sinapine fraction solution and / or sinapic acid fraction solution obtained in Reference Example 2 was concentrated using a freeze dryer and used to achieve the concentrations (wt %) shown in Table 8 below.

[0096]

[0097] (Sensory Evaluation) The bitterness and astringency of each of the evaluation solutions obtained above were evaluated by five panelists skilled in evaluation, who rated the results on a three-level scale shown in Table 9 in increments of one point, and the evaluation was conducted by consensus.

[0098]

[0099] The results are shown in Table 10.

[0100]

[0101] As shown in Table 10, it was confirmed that the bitterness and astringency returned in the evaluation solutions to which sinapine and / or sinapic acid had been added. In other words, it was confirmed that the rapeseed protein product 2 powder obtained in Example 2 did not contain sinapine or sinapic acid, and that these were removed by washing with salt water.

[0102] The present invention provides a method for purifying rapeseed protein that reduces the bitterness, astringency, etc., inherent in rapeseed protein, and rapeseed protein with reduced bitterness, astringency, etc. Thus, the present invention is useful in the food industry.

[0103] This application is based on patent application No. 2024-043685 filed in Japan (filing date: March 19, 2024), the contents of which are incorporated in their entirety herein.

Claims

1. A method for purifying rapeseed protein, comprising the step of washing an aqueous solution containing rapeseed protein with salt water.

2. The method of claim 1, wherein the salt concentration in the brine is 0.01% by weight to 10% by weight.

3. The method of claim 1, wherein the step of washing with brine is a step of subjecting the product to ultrafiltration using brine.

4. The purification method according to claim 3, wherein the nominal molecular weight cutoff of the ultrafiltration membrane used for ultrafiltration is 10,000 to 2,000,000.

5. The purification method according to claim 1, which comprises the step of desalting the aqueous solution obtained after the step of washing the aqueous solution containing rapeseed protein with salt water.

6. The purification method according to claim 1, further comprising the step of contacting the aqueous solution containing rapeseed protein with activated carbon.

7. The method for purifying rapeseed protein according to claim 6, wherein the aqueous solution containing the rapeseed protein is brought into contact with activated carbon at a pH of 5 to 11.

8. The purification method according to any one of claims 1 to 7, wherein the rapeseed protein is a high molecular weight rapeseed protein.

9. A purification method according to any one of claims 1 to 7, wherein the total content of sinapine and sinapic acid in rapeseed protein is reduced.

10. A purification method according to any one of claims 1 to 7, wherein the rapeseed napin content in the rapeseed protein is reduced.

11. A method for producing rapeseed protein having reduced bitterness and astringency, comprising the step of washing an aqueous solution containing rapeseed protein with salt water.

12. The method according to claim 11, wherein the salt concentration in the brine is 0.01% by weight to 10% by weight.

13. The method according to claim 11, wherein the step of washing with salt water is a step of subjecting the product to ultrafiltration using salt water.

14. The method according to claim 13, wherein the nominal molecular weight cutoff of the ultrafiltration membrane used for ultrafiltration is 10,000 to 2,000,000.

15. The method according to claim 11, further comprising the step of desalting the aqueous solution obtained after the step of washing the rapeseed protein-containing aqueous solution with salt water.

16. The method of claim 11, further comprising the step of contacting the aqueous solution containing rapeseed protein with activated carbon.

17. The method according to claim 16, wherein the pH of the rapeseed protein-containing aqueous solution is adjusted to 5 to 11 and the aqueous solution is brought into contact with activated carbon.

18. The method according to any one of claims 11 to 17, wherein the rapeseed protein is a high molecular weight rapeseed protein.

19. The method according to any one of claims 11 to 17, wherein the total content of sinapine and sinapic acid in rapeseed protein is reduced.

20. A method according to any one of claims 11 to 17, wherein the rapeseed napin content in the rapeseed protein is reduced.

21. Rapeseed protein having a total polyphenol content of 0.5% by weight or less.

22. Rapeseed protein having a tannic acid content of 0.5% by weight or less.

23. Rapeseed protein having a total content of sinapine and sinapic acid of 0.5% by weight or less.

24. Rapeseed protein having a rapeseed napin content of 0.1% by weight or less.

25. The rapeseed protein according to any one of claims 21 to 24, wherein the rapeseed protein is a high molecular weight rapeseed protein.

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