A process for the preparation of a high solubility pea protein composition and products prepared thereby

Abstract

The present invention relates to the field of pea protein composition processing. The present invention specifically relates to a method for preparing a high solubility pea protein composition and products prepared thereby. The method of the present invention comprises subjecting a pea protein composition to high pressure homogenization to obtain a homogenized pea protein composition, wherein the homogenized pea protein composition has a nitrogen solubility index greater than or equal to 88.0%. The present invention also provides a pea protein composition prepared by the method, which has better solubility.

Description

Technical Field

[0001] This invention relates to the field of pea protein composition processing. Specifically, this invention relates to a method for preparing a highly soluble pea protein composition and the product thereof. Background Technology

[0002] Peas are a high-quality nutritious food. They are rich in starch, protein, and dietary fiber. Pea protein is a nutritionally balanced plant protein. It is rich in lysine and contains many other essential amino acids required by the human body. The amino acid ratios in pea protein are close to the FAO / WHO recommendations. Pea protein is suitable for use in health supplements and as an additive in food or beverages (see *Journal of Zhengzhou Grain College*, December 1999, Vol. 20, No. 4, "Research on the Preparation of Pea Protein and Starch," Mo Chongwen). However, current pea protein products have significant problems with solubility and flavor, resulting in low market acceptance. The solubility of pea protein compositions is typically expressed using the Nitrogen Solubility Index (NSI). Summary of the Invention

[0003] This invention provides a method for preparing a highly soluble pea protein composition and the product thereof. The method includes a step of high-pressure homogenization of the pea protein composition, and optionally further includes flash evaporation and / or drying steps. The method significantly improves the solubility of the pea protein composition. This invention also provides a pea protein composition prepared by the method, which exhibits even better solubility. The pea protein composition obtained by the method of this invention has an NSI value greater than or equal to 88.0%, meeting industrial requirements for good solubility. Detailed Implementation

[0004] This invention provides a method for preparing a highly soluble pea protein composition, comprising subjecting the pea protein composition to high-pressure homogenization to obtain a homogenized pea protein composition. In some embodiments, the highly soluble pea protein composition of this invention has a nitrogen solubility index greater than or equal to 88.0%. In some embodiments, the homogenized pea protein composition obtained by the method of this invention has a nitrogen solubility index greater than or equal to 88.0%.

[0005] In some embodiments, the present invention provides a method for preparing a highly soluble pea protein composition, comprising subjecting the pea protein composition to high-pressure homogenization to obtain a homogenized pea protein composition, wherein the homogenized pea protein composition has a nitrogen solubility index greater than or equal to 88.0%.

[0006] In some embodiments, the pressure of the high-pressure homogenization is 5 MPa-200 MPa, and more preferably 40 MPa-200 MPa.

[0007] In some embodiments, the operating temperature of the high-pressure homogenizer is 10-70°C.

[0008] In some embodiments, the pea protein composition used in the method of the present invention is a fluid containing a pea protein composition. More specifically, the fluid containing a pea protein composition described herein is typically produced by dispersing pea protein isolate (most commonly in powder form) into a fluid. In some embodiments, the fluid is an aqueous fluid. In some embodiments, the fluid is a liquid, preferably an aqueous liquid.

[0009] In some embodiments, the high-pressure homogenization of the pea protein composition in the method of the present invention includes high-pressure homogenization of a fluid containing the pea protein composition. In some embodiments, the pH of the fluid is 4.4-10.0. In some embodiments, the pH of the fluid is 4.4-10.0, and the pressure of the high-pressure homogenization is 5 MPa-200 MPa.

[0010] In some embodiments, the high-pressure homogenization of the pea protein composition includes high-pressure homogenization of a fluid containing the pea protein composition, wherein the pH of the fluid is 4.4-10.0.

[0011] In some embodiments, the method of the present invention further includes flash evaporation of the pea protein composition, wherein high-pressure homogenization is performed before flash evaporation or after flash evaporation.

[0012] In some preferred embodiments, the present invention provides a method for preparing a highly soluble pea protein composition, comprising subjecting the pea protein-containing composition to high-pressure homogenization and flash evaporation, wherein the high-pressure homogenization is performed before the flash evaporation or the high-pressure homogenization is performed after the flash evaporation.

[0013] In some embodiments, the high-pressure homogenization of the pea protein composition in the method of the present invention includes high-pressure homogenization of a fluid containing the pea protein composition, and the method further includes flash evaporation of the fluid containing the pea protein composition, wherein high-pressure homogenization is performed before flash evaporation or after flash evaporation.

[0014] In some preferred embodiments, the present invention provides a method for preparing a highly soluble pea protein composition, comprising subjecting a fluid containing the pea protein composition to high-pressure homogenization and flash evaporation, wherein the high-pressure homogenization is performed before or after the flash evaporation.

[0015] Flash evaporation, as described in this article, refers to introducing a high-pressure liquid into a relatively low-pressure container (flash drum). Due to the sudden pressure drop, a portion of the liquid becomes saturated vapor and saturated liquid under the container's pressure. Further gas-liquid separation can be performed as needed. Typically, flash evaporation can achieve various purposes, such as separation and flavor correction (i.e., removing unpleasant odors through liquid evaporation), as required.

[0016] In another preferred embodiment, the method for preparing a highly soluble pea protein composition according to the present invention includes high-pressure homogenization of the pea protein composition to obtain a homogenized pea protein composition, wherein high-pressure homogenization of the pea protein composition includes high-pressure homogenization of a fluid containing the pea protein composition, wherein the pH value of the fluid is 4.4-10.0.

[0017] In another preferred embodiment, the method for preparing a highly soluble pea protein composition according to the present invention includes high-pressure homogenization of the pea protein composition to obtain a homogenized pea protein composition, wherein the high-pressure homogenization pressure is 5 MPa-200 MPa. In some embodiments, the high-pressure homogenization of the pea protein composition includes high-pressure homogenization of a fluid containing the pea protein composition, wherein the pH value of the fluid is 4.4-10.0.

[0018] In all embodiments of the invention, the method optionally includes drying the pea protein composition treated by the method. In some embodiments, the drying includes spray drying and freeze drying. The dried pea protein composition is a powdered (highly soluble) pea protein composition.

[0019] In some embodiments, the pea protein composition of the present invention is a composition comprising at least 30% by weight, at least 40% by weight, at least 50% by weight, at least 60% by weight, at least 70% by weight, at least 80% by weight, or at least 90% by weight of pea protein based on the dry weight of the composition. In some embodiments, the pea protein composition of the present invention is a composition comprising 30% to 100% by weight of pea protein based on the dry weight of the composition, for example, comprising 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 5%, 5%, or 54% by weight of the dry weight of the composition. Compositions of pea protein in the amounts of 55 wt%, 56 wt%, 57 wt%, 58 wt%, 59 wt%, 60 wt%, 61 wt%, 62 wt%, 63 wt%, 64 wt%, 65 wt%, 66 wt%, 67 wt%, 68 wt%, 69 wt%, 70 wt%, 71 wt%, 72 wt%, 73 wt%, 74 wt%, 75 wt%, 76 wt%, 77 wt%, 78 wt%, 79 wt%, 80 wt%, 81 wt%, 82 wt%, 83 wt%, 84 wt%, 85 wt%, 86 wt%, 87 wt%, 88 wt%, 89 wt%, 90 wt%, 91 wt%, 92 wt%, 93 wt%, 94 wt%, 95 wt%, 96 wt%, 97 wt%, 98 wt%, 99 wt%, or 100 wt%.

[0020] In some embodiments, the pea protein composition further comprises enzymatic hydrolysis and / or proteolytic hydrolysis products of pea protein. In some embodiments, the pea protein composition does not comprise enzymatic hydrolysis and / or proteolytic hydrolysis products of pea protein. In some embodiments, the pea protein composition of the present invention is a commercially available pea protein isolate or pea protein concentrate.

[0021] The fluid described in this invention can be a liquid fluid using a liquid as a carrier or a gaseous fluid using a gas as a carrier. The fluid containing the pea protein composition described in this invention can be a fluid obtained by dissolving and / or dispersing the pea protein composition described in this invention in a liquid carrier (solvent) or a gaseous carrier, wherein the liquid carrier (solvent) is preferably water. The fluid containing the pea protein composition is preferably an aqueous fluid. The fluid containing the pea protein composition described in this invention can also be a fluid containing the pea protein composition separated from pea starch production wastewater, wherein the fluid is preferably an aqueous fluid.

[0022] In all embodiments, the pressure for high-pressure homogenization described in this invention is an arbitrary range of values ​​selected from or within the ranges of 5MPa-200MPa, 15MPa-200MPa, 20MPa-200MPa, 5MPa-100MPa, and 8MPa-50MPa, such as 5MPa, 6MPa, 7MPa, 8MPa, 9MPa, 10MPa, 11MPa, 12MPa, 13MPa, 14MPa, 15MPa, 16MPa, 17MPa, 18MPa, 19MPa, 20MPa, 21MPa, 22MPa, 23MPa, 24MPa, 25MPa, 26MPa, 27MPa, 28MPa, 29MPa, 30MPa, 31MPa, 32MPa, 33MPa, 34MPa, 3... 5MPa, 36MPa, 37MPa, 38MPa, 39MPa, 40MPa, 41MPa, 42MPa, 43MPa, 44MPa, 45MPa, 46MPa, 47MPa, 48MPa, 49MPa, 50MPa, 55MPa, 60MPa, 65MPa, 70MPa, 75MPa, 80MPa, 85MPa, 90MPa, 95MPa, 100MPa, 105MPa, 110MPa, 115MPa, 120MPa, 125MPa, 130MPa, 135MPa, 140MPa, 145MPa, 150MPa, 155MPa, 160MPa, 165MPa, 170MPa, 175MPa, 180MPa, 185MPa, 190MPa, 195MPa and 200MPa. The high-pressure homogenization described herein has a general meaning in the art. Generally, high-pressure homogenization involves passing a fluid through a narrow gap or orifice under ultra-high pressure (typically, but not always above 10 MPa), rapidly reducing the pressure to create supersonic velocity, thereby generating strong combined forces of shearing, impaction, and cavitation to achieve a homogenization effect. High-pressure homogenization is typically performed using conventional methods in the art, such as high-pressure homogenizers, colloid mills, or shear emulsification pumps. In these embodiments, the pressure used in high-pressure homogenization according to this invention refers to the pressure before the homogenization valve of the homogenizer.

[0023] The pH value of the pea protein-containing composition fluid of the present invention is any value within the range of 4.4-10.0, 7.0-10.0, or 7.2-10.0, or any value within that range. The pH value of the pea protein-containing composition fluid described in this invention can be 4.4, 4.5, 4.6, 4.7, 4.8, 4.6, 5.0, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9.0, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, or 10.0. The pH value described in this invention is achieved by adding an acid or a base.

[0024] Permissible acids include, but are not limited to: hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, acetic acid, tartaric acid, succinic acid, maleic acid, fumaric acid, gluconic acid, citric acid, malic acid, ascorbic acid, phosphoric acid, sorbic acid, benzoic acid, tannic acid, palmitic acid, alginic acid, polyglutamic acid, polygalacturonic acid, and acidic amino acids. Permissible bases include, but are not limited to: alkali metal hydroxides, such as sodium hydroxide and potassium hydroxide; alkaline earth metal hydroxides, such as calcium hydroxide and magnesium hydroxide; and organic bases such as basic amino acids or N-methyl-D-glucosamine, potassium sorbate, and sodium benzoate.

[0025] The operating temperature of the high-pressure homogenizer described in this invention is any value within the range of 10-70℃, or any range of values ​​selected within that range. The operating temperature can be 10℃, 11℃, 12℃, 13℃, 14℃, 15℃, 16℃, 17℃, 18℃, 19℃, 20℃, 21℃, 22℃, 23℃, 24℃, 25℃, 26℃, 27℃, 28℃, 29℃, 30℃, 31℃, 32℃, 33℃, 34℃, 35℃, 36℃, 37℃, 38℃, or 30℃. The operating temperatures are 9℃, 40℃, 41℃, 42℃, 43℃, 44℃, 45℃, 46℃, 47℃, 48℃, 49℃, 50℃, 51℃, 52℃, 53℃, 54℃, 55℃, 56℃, 57℃, 58℃, 59℃, 60℃, 61℃, 62℃, 63℃, 64℃, 65℃, 66℃, 67℃, 68℃, 69℃, or 70℃. The operating temperature is the temperature of the pea protein composition just before the homogenization step.

[0026] The highly soluble pea protein composition of this invention refers to a pea protein composition treated by the method described in this invention (especially by the high-pressure homogenization).

[0027] The drying step described in this invention can be a drying step such as freeze drying or spray drying.

[0028] The beneficial effects of this invention include: the method of this invention can significantly improve the solubility of pea protein compositions. Without being bound by any theory, it is believed that the high-pressure homogenization can effectively reduce the particle size of the pea protein composition, thereby enhancing solubility. The particle size of the pea protein composition is ideally 40 micrometers (μm) or any value below 40 micrometers, such as 39μm, 38μm, 37μm, 36μm, 35μm, 34μm, 33μm, 32μm, 31μm, 30μm, 29μm, 28μm, 27μm, 26μm, 25μm, 24μm, 23μm, 22μm, 21μm, 20μm, 19μm, 18μm, 17μm, 16μm, 15μm, 14μm, 13μm, 12μm, 11μm, 10μm, 9μm, 8μm, 7μm, 6μm, 5μm, 4μm, 3μm, 2μm and 1μm, or more specifically any range consisting of any value between 12μm and 40μm. The particle size was determined using a Malvern laser particle size analyzer, model Malvern3000, with a particle size value of D[4.3].

[0029] The highly soluble pea protein composition (homogenized pea protein composition) obtained by the method described in this invention has an NSI value greater than or equal to 88.0%. For example, the NSI of the highly soluble pea protein composition (homogenized pea protein composition) obtained by the method described in this invention can be any NSI value within the range of 88.0% to 98.0%, 90.0% to 95.0%, or greater than or equal to 88.0%, or any NSI value within these ranges, such as 88.0%, 88.1%, 88.2%, 88.3%, 88.4%, 88.5%, 88.6%, 88.7%, 88.8%, 88.9%, 89.0%, 89.1%, 89.2%, 89.3%, 89.4%, 89.5%, etc. 89.6%, 89.7%, 89.8%, 89.9%, 90.0%, 90.1%, 90.2%, 90.3%, 90.4%, 90.5%, 90.6%, 90.7%, 90.8%, 90.9%, 91.0%, 91.1%, 91.2%, 91.3%, 91.4%, 91.5%, 91.6%, 91.7%, 91.8%, 91.9%, 92.0%, 92.1%, 92.2%, 92.3%, 92.4%, 92.5%, 92.6%, 92.7%, 92.8%, 92.9%, 93.0%, 9 3.1%, 93.2%, 93.3%, 93.4%, 93.5%, 93.6%, 93.7%, 93.8%, 93.9%, 94.0%, 94.1%, 94.2%, 94.3%, 94.4%, 94.5%, 94.6%, 94.7%, 94.8%, 94.9%, 95.0%, 95.1%, 95.2%, 95.3%, 95.4%, 95.5%, 95.6%, 95.7%, 95.8%, 95.9%, 96.0%, 96.1%, 96.2%, 96.3%, 96.4%, 96.5%, 9 6.6%, 96.7%, 96.8%, 96.9%, 97.0%, 97.1%, 97.2%, 97.3%, 97.4%, 97.5%, 97.6%, 97.7%, 97.8%, 97.9%, 98.0%, 98.1%, 98.2%, 98.3%, 98.4%, 98.5%, 98.6%, 98.7%, 98.8%, 98.9%, 99.0%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9%, 100.0%, etc.

[0030] This invention also provides a pea protein composition product having an NSI value greater than or equal to 88.0%. For example, the NSI of the pea protein composition can be any NSI value within or between the range of 88.0%, such as 88.0%, 88.1%, 88.2%, 88.3%, 88.4%, 88.5%, 88.6%, 88.7%, 88.8%, 88.9%, 89.0%, 89.1%, 89.2%, 89.3%, 89.4%, 89.5%, 89.6%, 89.7%, 89.8%, 89.9%, 90.0%, 90.1%, and 90.2%. 90.3%, 90.4%, 90.5%, 90.6%, 90.7%, 90.8%, 90.9%, 91.0%, 91.1%, 91.2%, 91.3%, 91.4%, 91.5%, 91.6%, 91.7%, 91.8%, 91.9%, 92.0%, 92.1%, 92.2%, 92.3%, 92.4%, 92.5%, 92.6%, 92.7%, 92.8%, 92.9%, 93.0%, 93.1%, 93.2%, 93.3%, 93.4%, 93.5% %, 93.6%, 93.7%, 93.8%, 93.9%, 94.0%, 94.1%, 94.2%, 94.3%, 94.4%, 94.5%, 94.6%, 94.7%, 94.8%, 94.9%, 95.0%, 95.1%, 95.2%, 95.3%, 95.4%, 95.5%, 95.6%, 95.7%, 95.8%, 95.9%, 96.0%, 96.1%, 96.2%, 96.3%, 96.4%, 96.5%, 96.6%, 96.7%, 96. 8%, 96.9%, 97.0%, 97.1%, 97.2%, 97.3%, 97.4%, 97.5%, 97.6%, 97.7%, 97.8%, 97.9%, 98.0%, 98.1%, 98.2%, 98.3%, 98.4%, 98.5%, 98.6%, 98.7%, 98.8%, 98.9%, 99.0%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9%, 100.0%, etc.

[0031] In these embodiments, the NSI value of the pea protein composition of the present invention can be determined by the Kjeldahl nitrogen determination method according to the National Standard of the People's Republic of China GB5009.5-2010 (National Food Safety Standard – Determination of Protein in Food, promulgated on March 26, 2010, and implemented on June 1, 2010).

[0032] In some embodiments, the pea protein composition of the present invention comprises non-pea protein components such as polysaccharides and ash, in addition to pea protein. Generally, the non-pea protein components in the pea protein composition of the present invention have no effect on the nitrogen solubility index of the pea protein composition. In some embodiments, the nitrogen solubility index of the pea protein composition of the present invention does not change with variations in the content of non-pea protein components in the pea protein composition.

[0033] The present invention also provides a composition comprising the highly soluble pea protein composition of the present invention (sometimes referred to as the pea protein composition of the present invention for simplicity).

[0034] The highly soluble pea protein compositions described in all embodiments of the present invention can be used to prepare food, feed, cosmetics, pharmaceuticals, dietary supplements, such as meat products, flour products, dairy products, and beverages such as functional beverages. Attached Figure Description

[0035] Figure 1 This is a diagram illustrating the NSI of pea protein compositions obtained under different homogenization pressures.

[0036] Figure 2 This is a diagram showing the particle size of pea protein compositions obtained under different homogenization pressures.

[0037] Figure 3 This is a graph of the amide I band in the infrared spectrum of sample 1.

[0038] Figure 4 This is a graph of the amide I band in the infrared spectrum of sample 11.

[0039] Figure 5 This is a graph of the amide I band in the infrared spectrum of sample 13.

[0040] Figure 6 This is a graph of the amide I band in the infrared spectrum of sample 14.

[0041] Figure 7 This is a graph of the amide I band in the infrared spectrum of sample 15.

[0042] The present application will now describe specific embodiments. These specific embodiments are exemplary and not restrictive.

[0043] Materials and Methods

[0044] 1. Main experimental materials

[0045] Pea protein isolate (pea protein isolate (80% protein) purchased from Yantai Dongfang Protein Technology Co., Ltd.); sodium hydroxide (NaOH), analytical grade; deionized water.

[0046] 2. Main experimental instruments and equipment

[0047] pH meter; 2000ml jacketed beaker; stirrer; high-pressure homogenizer, model APV1000; freeze dryer; constant temperature hot water circulator; laser particle size analyzer; texture analyzer; FOSS automatic Kjeldahl nitrogen analyzer.

[0048] 3. Experimental Methods

[0049] 3.1 Homogenization treatment of pea protein composition

[0050] Add 440g of pea protein isolate to a container, then add deionized water and stir to disperse the pea protein isolate, thereby preparing a 4000ml fluid containing the pea protein composition. Heat the fluid containing the pea protein composition to 60°C and adjust the pH to 7.2 with NaOH. Divide the fluid containing the pea protein composition at pH 7.2 into 16 equal portions of 250ml each, labeled as Samples 1-16.

[0051] Sample 1 was the control group without high-pressure homogenization, and Samples 2-16 were the treatment groups that underwent high-pressure homogenization at pressures of 1 MPa, 2 MPa, 3 MPa, 4 MPa, 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa, 10 MPa, 15 MPa, 20 MPa, 30 MPa, 40 MPa and 50 MPa, respectively.

[0052] Finally, samples 1-16 were freeze-dried to obtain the dried control pea protein composition from sample 1 and the dried highly soluble pea protein composition from samples 2-16.

[0053] 3.2 Detection of Nitrogen Solubility Index (NSI)

[0054] The dried control pea protein composition from Sample 1 and the dried highly soluble pea protein compositions from Samples 2-16 were respectively formulated into liquids for Samples 1-16.

[0055] Take 20 ml of each of samples 1-16 and dilute them to 100 ml in a volumetric flask. Mix well and accurately pipette 10 ml of each flask to obtain the total nitrogen determination solution for samples 1-16. Transfer this solution to a 250 ml nitrogen determination flask for testing. After allowing the remaining fluid to stand for 1-2 minutes, transfer the supernatant of the fluids from samples 1-16 in the volumetric flask to a centrifuge tube. Centrifuge at 1500 rpm for 10 minutes to obtain the centrifuged liquid of samples 1-16. Filter the centrifuged liquid of samples 1-16 through rapid filter paper (or glass fiber) to obtain the clear filtrate of samples 1-16. Place the clear filtrate of samples 1-16 in an Erlenmeyer flask to obtain the water-soluble nitrogen determination solution for samples 1-16. Accurately pipette 10 ml of the water-soluble nitrogen determination solution of samples 1-16 into a 250 ml nitrogen determination flask. The contents of water-soluble nitrogen and total nitrogen were determined using the method consistent with Method I (Kjeldahl method) in the National Standard of the People's Republic of China GB5009.5-2010 (National Food Safety Standard—Determination of Protein in Food, promulgated on March 26, 2010, and implemented on June 1, 2010). The specific steps are as follows:

[0056] Sample preparation: In a nitrogen determination flask containing the test solution, add 0.2 g copper sulfate, 6 g potassium sulfate, and 20 ml sulfuric acid. Shake gently and place in a digestion furnace for digestion. Heat carefully; once the contents are completely carbonized and foaming has completely stopped, increase the temperature while maintaining a gentle boil until the fluid turns blue-green and becomes clear and transparent. Continue heating for 0.5 to 1 hour. Remove from heat and allow to cool. Carefully add 20 ml of water. After cooling, transfer to a 250 ml volumetric flask and rinse the nitrogen determination flask with a small amount of water. Add the washings to the volumetric flask, then add water to the mark and mix well. Perform a reagent blank test simultaneously.

[0057] Determination: The determination was performed using a FOSS automatic Kjeldahl nitrogen analyzer (model 2300). Before turning on the equipment, turn on the cooling water, then turn on the power and wait for the instrument to self-calibrate. After self-calibration, select "Measurement Mode". Select "PROGRAM 2" to begin the cleaning program. Place the empty test tube into the instrument, ensuring it is sealed and stable. Once stable, pull down the sealing door to close it; the cleaning program will start automatically. Repeat several times until the instrument displays "N%" as 0. After the cleaning program is complete, replace the empty sample tube. Select "PROGRAM 3" on the panel, then select "Blank" to begin the blank sample testing program. Pull down the sealing door; the program will start automatically. After the blank sample testing program is complete, replace the empty sample tube. Select "Determine Nitrogen Content" and enter the volume of the sample to be processed. Pull down the sealing door; the measurement program will start. After the measurement is complete, the measurement results will be displayed on the instrument panel. Using the total nitrogen determination solution and water-soluble nitrogen determination solution for samples 1-16, determine the total nitrogen content (g / 100ml) and water-soluble nitrogen content (g / 100ml) of samples 1-16, respectively.

[0058] The NSI values ​​of samples 1-16 are calculated according to the following formula:

[0059] NSI% = (Water-soluble nitrogen content) / (Total nitrogen content) × 100.

[0060] 3.3 Particle size detection

[0061] Two g each of the dried control pea protein composition from Sample 1 and the dried highly soluble pea protein compositions from Samples 2-16 were prepared into 40 ml solutions with a 5% concentration. The particle size of each of Samples 1-16 was determined using a laser particle size analyzer.

[0062] 4. Results and Discussion

[0063] 4.1 The NSI and particle size test results of homogenized pea protein composition samples and non-homogenized pea protein composition samples are summarized in Table 1.

[0064] Table 1: Summary of Test Results

[0065]

[0066]

[0067] 4.2 Nitrogen Solubility Index (NSI) as a Representation of Solubility Improvement

[0068] The test results show that the NSI of the pea protein composition sample without high-pressure homogenization was 13.60%. However, the NSI of the pea protein composition sample after high-pressure homogenization increased with increasing homogenization pressure. It was also observed that when the homogenization pressure reached approximately 10 MPa, the NSI decreased slightly before rebounding. When the homogenization pressure reached 20 MPa, the NSI approached 100%. The experimental results demonstrate that high-pressure homogenization significantly improves the solubility of the pea protein composition. The nitrogen solubility index at different homogenization pressures is illustrated in the figure below. Figure 1 middle.

[0069] 4.3 Changes in particle size

[0070] The experimental results show that the particle size of the pea protein composition is significantly reduced after high-pressure homogenization. Furthermore, the particle size of the pea protein composition gradually decreases with increasing homogenization pressure. The particle size distribution under different homogenization pressures is illustrated in the figure below. Figure 2 middle.

[0071] Reducing the particle size of pea protein compositions helps improve solubility and mouthfeel.

[0072] 5. Effects of high-pressure homogenization on the secondary structure of pea protein

[0073] Protein secondary structure refers to the local spatial structure of the polypeptide backbone. Common secondary structures include regular structures such as α-helices and β-sheets, semi-regular structures such as β-turns, and random coil structures. Fourier transform infrared spectroscopy (FT-IR) is a molecular vibrational absorption spectroscopy method commonly used for detecting protein secondary structure. The infrared absorption spectrum of proteins mainly consists of a series of amide absorption bands, including amide I-VII and A and B bands. The most sensitive spectral region for protein secondary structure is the amide I band (1700-1600 cm⁻¹). -1 The amide I band in the infrared spectrum is almost entirely generated by the stretching vibration of C=O. Therefore, the amide I band contains compositional information about the protein's secondary structure. In this application, by quantitatively analyzing the structural units of the protein's secondary structure in the amide I band of the infrared spectrum, the changes in the secondary structure of pea protein in the pea protein composition caused by high-pressure homogenization were confirmed.

[0074] 5.1 Materials and Equipment

[0075] Sample 1: Dry control pea protein composition (control group without high-pressure homogenization); Sample 11: Dry highly soluble pea protein composition (treated group treated with high-pressure homogenization at 10 MPa); Sample 13: Dry highly soluble pea protein composition (treated group treated with high-pressure homogenization at 20 MPa); Sample 14: Dry highly soluble pea protein composition (treated group treated with high-pressure homogenization at 30 MPa); Sample 15: Dry highly soluble pea protein composition (treated group treated with high-pressure homogenization at 40 MPa). Potassium bromide (KBr), spectrally pure.

[0076] Infrared spectrometer, FT-IR, NICOLET iS10, Thermo Fisher Scientific Inc.

[0077] 5.2 Experimental Methods

[0078] In an agate mortar, 1.5 mg of each pea protein composition sample and 200 mg of KBr were thoroughly ground, dried at 100°C, and cooled in a desiccator until ready for use. Tablets were then prepared using a powder tableting machine at a pressure of 9-10t. Pure KBr tablets were prepared using the same method.

[0079] Background was read from pure KBr pellets using an infrared spectrometer. After measuring the pellet containing the sample and subtracting the background, the amide I band (1700-1600 cm⁻¹) was obtained. -1 The infrared spectrum.

[0080] The obtained infrared spectrum was analyzed using OMNIC software. After automatic baseline correction, peaks were labeled and the corrected peak areas of each peak were measured. The obtained data are shown below.

[0081] 5.3 Results and Discussion

[0082] The infrared spectra and the percentage of the area of ​​the correction peak for each sample are calculated as follows.

[0083] Table 2

[0084] Infrared spectral data of sample 1 (control group without high-pressure homogenization)

[0085] 1 1684.06 18.80 β-turn 2 1675.11 4.09 β-sheet 3 1669.62 7.90 β-turn 4 1662.46 5.18 β-turn 5 1653.18 21.80 α-helix 6 1646.84 11.17 irregular curl 7 1635.70 15.80 β-sheet 8 1623.67 8.72 β-sheet 9 1617.15 6.54 β-sheet

[0086] The infrared spectrum of sample 1 is as follows Figure 3 As shown.

[0087] Table 3

[0088] Infrared spectral data of sample 11 (high-pressure homogenization group under 10 MPa pressure).

[0089]

[0090]

[0091] The infrared spectrum of sample 11 is as follows Figure 4 As shown.

[0092] Table 4

[0093] Infrared spectral data of sample 13 (high-pressure homogenization group under 20 MPa pressure).

[0094]

[0095] The infrared spectrum of sample 13 is as follows Figure 5 As shown.

[0096] Table 5

[0097] Infrared spectral data of sample 14 (high-pressure homogenization group under 30 MPa pressure).

[0098]

[0099] The infrared spectral data of sample 14 are as follows Figure 6 As shown.

[0100] Table 6

[0101] Infrared spectral data of sample 15 (high-pressure homogenization group under 40 MPa pressure).

[0102]

[0103]

[0104] The infrared spectrum of sample 15 is as follows Figure 7 As shown.

[0105] Table 7

[0106] The proportions of structural units in the secondary structures of samples 1 and 6-9 are shown below:

[0107]

[0108] Amide I band (1700 cm⁻¹) from the infrared spectra of various pea protein samples -1 Up to 1600cm -1 The comparison shows that:

[0109] In the infrared spectra of pea protein samples 11, 13, 14, and 15 after high-pressure homogenization, the number of peaks appearing in the amide I band range increased compared to pea protein sample 1 without high-pressure homogenization. This indicates that the secondary structure of pea protein changed after high-pressure homogenization.

[0110] Changes in the secondary structure of a protein can lead to significant changes in its functional properties.

[0111] The newly added peaks (i.e., the infrared spectra generated by the newly emerging secondary structures) all appear at both ends of the amide I band. The structures appearing in these regions generally belong to the β conformation, i.e., β-sheets or β-turns.

[0112] Quantitative analysis of the secondary structure showed a significant increase in the proportion of β-sheets in the secondary structure of pea protein after high-pressure homogenization. This is beneficial for improving solubility.

[0113] 5.4 Conclusion

[0114] High-pressure homogenization significantly alters the secondary structure of pea protein. The increased proportion of the β-conformation leads to substantial changes in its functional properties.

[0115] 6. Conclusion

[0116] The primary purpose of homogenization technology in the production of soy protein isolate is to improve the product's gelling properties. Soy protein typically has excellent solubility, while pea protein compositions generally have poor solubility. Low solubility directly impacts the application range of pea protein compositions in the food industry. Therefore, improving and enhancing solubility is a primary objective of pea protein composition research.

[0117] The results of the experiments in this invention show that high-pressure homogenization can significantly improve the solubility of pea protein compositions, thus solving the technical problem of low solubility of pea protein compositions.

[0118] High-pressure homogenization also altered the secondary structure of pea protein in the pea protein composition.

[0119] It is believed that high-pressure homogenization alters the pea protein composition in many ways (e.g., particle size), thereby contributing to improved solubility of the pea protein composition.

Claims

1. A method for preparing a highly soluble pea protein composition, comprising subjecting the pea protein composition to high-pressure homogenization to obtain a homogenized pea protein composition, wherein the homogenized pea protein composition has a nitrogen solubility index greater than or equal to 88.0%, and wherein the high-pressure homogenization of the pea protein composition comprises subjecting a fluid containing the pea protein composition to high-pressure homogenization, wherein the pH of the fluid is 7.2-10.0, and wherein the pressure of the high-pressure homogenization is 20 MPa-200 MPa.

2. The method according to claim 1, wherein high-pressure homogenization of the pea protein composition comprises high-pressure homogenization of a fluid containing the pea protein composition, and the method further comprises flash evaporation of the fluid containing the pea protein composition, wherein the high-pressure homogenization is performed before or after the flash evaporation.

3. The method according to claim 1, wherein the high-pressure homogenization is carried out at a temperature of 10-70°C.

4. The method according to claim 1, wherein the method further comprises drying the pea protein composition treated by the method.

5. The method of claim 4, wherein the drying comprises freeze drying or spray drying.

6. The method according to claim 1, wherein the nitrogen solubility index is greater than or equal to 92.0%.

7. The method of claim 1, wherein the pea protein composition is a composition containing 30% to 100% pea protein based on the dry weight of the composition.

8. The method according to claim 1, wherein the fluid containing the pea protein composition is an aqueous liquid containing the pea protein composition.

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