High-solubility and high-stability protein powder containing acidic functional components, acidic functional protein beverage and preparation method

Abstract

The invention discloses high-solubility and high-stability protein powder containing an acidic functional component. The protein powder comprises the following components in percentage by mass: 70-92% of soybean protein isolate, 1-3% of the acidic functional component and 4.52-16.5% of a composite dissolution-promoting dispersion-stabilizing component, the composite dissolution-promoting and dispersion-stabilizing component is prepared from the following components in percentage by mass: 3 to 10 percent of isomaltooligosacharide, 1.5 to 6 percent of fructo-oligosaccharide and 0.02 to 0.5 percent of stevioside; the invention further discloses a preparation method of the high-solubility and high-stability protein powder containing the acidic functional components. The invention further discloses an acidic functional protein beverage and a preparation method thereof. The brewing dissolution speed and the solution stability are remarkably improved through an oligosaccharide-sweetening agent compounding system, the dry mixing process is simple, complex modification treatment is not needed, the cost is lower than that of an enzymolysis or microcapsule technology, and the good industrialization advantage is achieved.

Description

Technical Field

[0001] This invention relates to the field of functional food technology, specifically to a protein powder with high solubility and high stability containing acidic functional ingredients, an acidic functional protein beverage, and a preparation method thereof. Background Technology

[0002] Protein powders and drinks with added acidic flavoring functional ingredients have become an important choice for protein supplementation due to their high nutritional value, unique flavor, and good taste. However, in acidic systems, protein solutions are prone to irreversible aggregation when reaching or approaching their isoelectric point, leading to a sharp drop in solubility. This severely affects the convenience of consuming protein powder and the sensory experience of protein powder drinks, including their appearance and taste. Specific issues are as follows:

[0003] 1. Clumping problem during brewing: When protein powder containing acidic components comes into contact with water, the local pH drops sharply to the isoelectric point, causing the protein to aggregate instantly and form insoluble clumps;

[0004] 2. Precipitation and stratification problem: Even after forced stirring to dissolve, the protein powder in the acidic solution continues to aggregate due to its proximity to the isoelectric point, resulting in precipitation after standing.

[0005] 3. Flavor-stability contradiction: Adding alkaline buffers (such as sodium bicarbonate) can improve solubility, but neutralizing the acidity will ruin the flavor of acidic protein drinks.

[0006] To address the aforementioned issues, traditional improvement methods employ enzymatic hydrolysis, but these methods have several drawbacks. For instance, enzymatic hydrolysis can easily produce bitter peptides, chemical modification processes are complex and do not align with the trend towards clean labeling, and thickeners (such as pectin) only delay sedimentation and cannot solve fundamental problems like protein molecule aggregation.

[0007] Currently, there is no technical solution to construct hydrogen bond bridging networks through oligosaccharide-sweetener compound systems to enhance protein powder solubility and inhibit protein solution isoelectric point aggregation. Summary of the Invention

[0008] To overcome the above-mentioned technical problems, this invention discloses a protein powder with high solubility and high stability containing acidic functional ingredients, an acidic functional protein beverage, and a preparation method thereof.

[0009] The technical solution adopted by the present invention to achieve the above objectives is as follows:

[0010] A highly soluble and stable protein powder containing acidic functional ingredients, the protein powder comprising the following components by mass percentage: 70-92% soy protein isolate, 1-3% acidic functional ingredients, and 4.52-16.5% complex dissolution-promoting and dispersing stabilizing components.

[0011] The aforementioned protein powder with high solubility, high stability, and acidic functional components, wherein, by mass percentage, the composite dissolution-promoting, dispersing, and stabilizing components include 3-10% isomaltooligosaccharide, 1.5-6% fructooligosaccharide, and 0.02-0.5% steviol glycosides.

[0012] The above-mentioned highly soluble and stable protein powder containing acidic functional ingredients, wherein the isomaltooligosaccharide contains ≥50% α-1,6 glycosidic bonds, has a degree of polymerization of 3-5, a molecular weight of 500-900 Da, and ≥10 free hydroxyl groups per molecule;

[0013] The branched structure ratio in isomaltooligosaccharides is: panose > isomalttriose > isomaltose, and the panose content is ≥35%.

[0014] The aforementioned protein powder with high solubility, high stability, and acidic functional components contains fructooligosaccharides with a degree of polymerization of 2-4 accounting for >60%, a molecular weight of 300-650 Da, a purity of ≥95%, and a hydroxyl content of ≥40%.

[0015] The aforementioned protein powder with high solubility, high stability, and acidic functional components contains steviosides with a content of ≥80% ribobadiin M, a hydrophilic to hydrophobic group ratio of 4:1, and a molecular weight of 950–1000 Da.

[0016] The protein powder with high solubility, high stability and acidic functional ingredients mentioned above has a dissolution time of ≤30 seconds at 20°C, based on a ratio of 30g powder / 200ml water.

[0017] The amount of sediment in the protein powder preparation solution after standing for 30 minutes is ≤0.5ml / 100ml;

[0018] The instant centrifugation sedimentation rate of the protein powder preparation solution is ≤4.5%;

[0019] The solubility index of the protein powder in the brewing solution is ≥80%.

[0020] The aforementioned protein powder with high solubility and high stability containing acidic functional ingredients, wherein the acidic functional ingredients are at least one of hawthorn powder, jujube powder, sour cherry powder, lemon powder, dried plum powder, schisandra powder, cornus powder, malic acid powder, or yogurt powder containing probiotics.

[0021] A method for preparing a protein powder with high solubility, high stability, and acidic functional components, wherein the preparation method is used to prepare the protein powder with high solubility, high stability, and acidic functional components as described above.

[0022] The preparation method includes the following steps:

[0023] Step 1: Mix the acidic functional ingredients, fructooligosaccharides, and steviol glycosides for 10 minutes to obtain a premix.

[0024] Step 2: Add soy protein isolate and isomaltooligosaccharide to the premix and mix for 20 minutes to obtain a protein powder with high solubility, high stability and acidic functional components.

[0025] An acidic functional protein beverage, the protein beverage comprising protein powder with high solubility, high stability and acidic functional components as described above;

[0026] The pH of the protein beverage is 2.5–5;

[0027] The protein beverage had a centrifugal sedimentation rate of ≤6% after standing at 4°C for 30 days.

[0028] The solubility index of the protein beverage after standing at 4°C for 30 days is ≥75%.

[0029] A method for preparing an acidic functional protein beverage, the method being used to prepare the acidic functional protein beverage as described above;

[0030] The preparation method includes:

[0031] Step I: Dry mix soy protein isolate, isomaltooligosaccharide, fructooligosaccharide and steviol glycosides to obtain a mixed powder;

[0032] Step II: Dissolve the mixed powder in pure water with a pH of 6-7 and a temperature of 20-30°C, stir and homogenize to obtain a protein solution;

[0033] Step III: Dissolve the acidic functional ingredients in purified water at 20-30°C, stir and add the protein solution, homogenize, and adjust the pH to 2.5-5 to obtain an acidic protein functional beverage.

[0034] The beneficial effects of this invention include the following:

[0035] (1) This invention significantly improves the brewing and dissolution speed and solution stability through the oligosaccharide-sweetener compound system. The dry mixing process is simple, requires no complex modification treatment, and has a lower cost than enzymatic hydrolysis or microencapsulation technology, thus having good industrialization advantages.

[0036] (2) New discovery of synergistic effect: The addition of the steviosides made the IMO / FOS system dissolve faster, with lower immediate precipitation and centrifugal precipitation rate and higher solubility index, proving that its hydrophobic anchoring effect is crucial to solubility and stability.

[0037] (3) Breakthrough in both quick dissolution and stability: For the first time, a compatibility effect of "30-second quick dissolution + 30-minute sedimentation amount ≤0.5ml / 100ml" is achieved in solid protein powder containing acidic functional ingredients. The sedimentation rate of the protein powder after brewing and dissolving is ≤4.5% after immediate centrifugation. The sedimentation rate of the acidic functional protein beverage is ≤6% after standing at 4℃ for 30 days.

[0038] (4) To address the issue of clumping during brewing, isomaltooligosaccharides and fructooligosaccharides bind to the polar groups of protein powder through hydroxyl hydrogen bonds, forming a hydration layer barrier that prevents direct contact between soy protein isolate and acidic functional components, thus delaying the sudden drop in local pH.

[0039] (5) To address the issue of isoelectric point precipitation, steviol glycosides anchor the hydrophobic regions of soy protein isolate, inhibiting hydrophobic group aggregation through surface-like effects, and synergistically constructing a "hydrogen bond-hydrophobic dual-region protective layer" with fructooligosaccharides to inhibit isoelectric point aggregation and improve system stability;

[0040] (6) To address the problem of low dissolution rate, the branched structure of isomaltooligosaccharide can produce a stereoblocking effect, blocking the hydrophobic binding of proteins, effectively reducing the viscosity of the solution, and promoting powder dispersion. Detailed Implementation

[0041] The present invention will be further described below through specific embodiments, so as to make the technical solution of the present invention easier to understand and master, rather than to limit the present invention.

[0042] In this embodiment, unless otherwise specified, all reagents are commercially available.

[0043] In this embodiment, unless otherwise specified, all methods used are conventional methods.

[0044] This invention discloses a protein powder with high solubility and high stability containing acidic functional ingredients. The protein powder comprises the following components by mass percentage: 70-92% soy protein isolate, 1-3% acidic functional ingredients, and 4.52-16.5% compound solubility-promoting, dispersing, and stabilizing components.

[0045] The composite dissolution-promoting and dispersing stabilizing component, by mass percentage, comprises 3-10% isomaltooligosaccharide, 1.5-6% fructooligosaccharide, and 0.02-0.5% steviol glycosides.

[0046] Preferably, the isomaltooligosaccharide (IMO) is composed of glucose linked by α-1,6 glycosidic bonds and mainly contains isomaltose (disaccharide), panose (trisaccharide), etc. The branched structure of the isomaltooligosaccharide (containing α-1,6 glycosidic bonds) can produce a stereobarrier effect, blocking the hydrophobic binding of proteins, reducing the viscosity of the solution, and promoting the dispersion of powder.

[0047] The branched structure ratio in the oligoisomaltose is: panose > isomalttriose > isomaltose, and the panose content is ≥35%, with the branched terminal hydroxyl groups of the branched structure providing additional anchoring sites;

[0048] The content of α-1,6 glycosidic bonds in the oligoisomaltose is ≥50%, and the higher the proportion of branched structure, the stronger the steric hindrance effect, which is the key to inhibiting the hydrophobic association of soy protein isolate SPI.

[0049] The degree of polymerization of the isomaltooligosaccharide is 3 to 5. Since the viscosity increases dramatically when the degree of polymerization DP > 7, the optimal balance between steric barrier and viscosity is achieved when the degree of polymerization DP is controlled at 3 to 5.

[0050] The molecular weight of the isomaltooligosaccharide is 500-900 Da, and this molecular weight range has a significant effect on reducing the viscosity of the solution.

[0051] The number of free hydroxyl groups in the isomaltooligosaccharide is ≥10 per molecule. The orientation of the hydroxyl groups at positions C2 / C3 affects the hydrogen bond angle with soy protein isolate (SPI). A higher proportion of free hydroxyl groups results in higher binding efficiency.

[0052] Preferably, the fructooligosaccharides and isomaltooligosaccharides can bind to the polar groups of the protein powder through hydroxyl hydrogen bonds to form a hydration layer barrier, preventing the protein powder from directly contacting the acidic functional components and delaying the sudden drop in local pH, thereby solving the problem of protein powder clumping when brewing.

[0053] The oligofructose has a degree of polymerization of 2-4 accounting for more than 60%. Since the lower the degree of polymerization (DP), the smaller the molecular weight, the stronger the penetration, and the faster the hydrogen bond formation rate, but the hydroxyl density is insufficient when the degree of polymerization (DP) is less than 2, the hydroxyl density and hydrogen bond formation rate are optimal when the degree of polymerization is controlled between 2 and 4.

[0054] The molecular weight of the oligofructose is 300-650 Da, which facilitates the insertion of the oligofructose into the interprotein gaps to form a dense hydration layer;

[0055] The purity of the oligofructose is ≥95%, which effectively avoids impurities (glucose / sucrose) competing for water and weakening the hydration barrier effect;

[0056] The hydroxyl content of the oligofructose is ≥40%, and the hydroxyl density is ≥13 hydroxyl groups per molecule (DP3), which can provide sufficient hydrogen bond sites to enhance the binding force of soy protein isolate SPI.

[0057] Preferably, the steviol glycoside has both hydrophilic aglycone and hydrophobic sugar group, which can anchor to the hydrophobic region of the protein and inhibit the aggregation of hydrophobic group through a surface-like effect. When combined with fructooligosaccharides, it forms a "hydrophilic-hydrophobic dual-region protective layer" to improve the stability of the system.

[0058] The stevioside contains ≥80% Rebaudioside M. Rebaudioside A has a weak inhibitory effect on aggregation due to its high number of hydrophilic groups, while Rebaudioside M has both high sweetness and amphiphilicity.

[0059] The ratio of hydrophilic to hydrophobic groups in the steviol glycosides is 4:1. A higher proportion of hydrophilic aglycone (glucose) results in better water solubility, while the hydrophobic aglycone (stevioside) is embedded in the protein's hydrophobic pocket.

[0060] The molecular weight of the steviol glycoside is 950-1000 Da, preferably 967 Da (Reb M) when the surface-like activity is strongest.

[0061] Preferably, at 20°C, the dissolving time of the protein powder is ≤30 seconds based on a ratio of 30g powder / 200ml water;

[0062] The amount of sediment in the protein powder preparation solution after standing for 30 minutes is ≤0.5ml / 100ml;

[0063] The instantaneous centrifugation sedimentation rate (4000 rpm / 10 min) of the protein powder preparation solution is ≤4.5%;

[0064] The solubility index of the protein powder in the brewing solution is ≥80%.

[0065] Preferably, the acidic functional ingredient is at least one of hawthorn powder, jujube powder, sour cherry powder, lemon powder, dried plum powder, schisandra powder, cornus powder, malic acid powder, or yogurt powder containing probiotics; specifically, hawthorn powder has a beneficial effect on muscle maintenance, sour cherry powder helps improve memory and cognition, protects nerves, and has anti-inflammatory and antioxidant effects, dried plum powder has an improving effect on symptoms of muscle relaxation and weakness, schisandra powder is beneficial for improving muscle function, cornus powder effectively improves symptoms such as physical weakness, eye fatigue, pale complexion, and muscle relaxation, and yogurt powder containing probiotics prevents gynecological and urinary tract infections.

[0066] The present invention also discloses a method for preparing a protein powder with high solubility, high stability and acidic functional components, wherein the preparation method is used to prepare the protein powder with high solubility, high stability and acidic functional components as described above.

[0067] The preparation method includes the following steps:

[0068] Step 1: Add the acidic functional ingredients, fructooligosaccharides and steviol glycosides into a small mixer and mix for 10 minutes to obtain a premix.

[0069] Step 2: Add soy protein isolate, isomaltooligosaccharide and the premix to a large mixer and mix for 20 minutes to obtain a protein powder with high solubility, high stability and acidic functional components.

[0070] Specifically, according to the production instructions, the soy protein isolate, hawthorn powder, isomaltooligosaccharide, fructooligosaccharide, and steviol glycosides can be accurately weighed using a weighing instrument. The weighed materials are then placed into PE bags, sealed, and a material card is filled out and attached to the weighed materials for later use.

[0071] After step 2 is completed, the protein powder is transported to the packaging machine through the material conveying pipeline for repackaging. During this process, the net content is checked every 30 minutes to ensure it is within the range required by the production order. The repackaged cans are then transported to an automatic can sealing machine with metal bottom caps for sealing. The sealing is checked every 2 hours. Finally, the cans are printed, capped, boxed, and stored according to the production order requirements.

[0072] The present invention also discloses an acidic functional protein beverage, the protein beverage comprising protein powder containing acidic functional ingredients with high solubility and high stability as described above;

[0073] The protein beverage has a pH of 2.5 to 5; preferably, when the pH is 3.5 to 3.8, it retains the characteristic sour taste of hawthorn and does not require the addition of alkaline additives.

[0074] The protein beverage exhibits a centrifugal sedimentation rate (4000 rpm / 10 min) of ≤6% after standing at 4℃ for 30 days, and no visible sediment is observed.

[0075] The solubility index of the protein beverage after standing at 4°C for 30 days is ≥75%.

[0076] The present invention discloses a method for preparing an acidic functional protein beverage, the method being used to prepare the acidic functional protein beverage as described above.

[0077] The preparation method includes:

[0078] Step I: Dry mix soy protein isolate, isomaltooligosaccharide, fructooligosaccharide and steviol glycosides to obtain a mixed powder;

[0079] Step II: Dissolve the mixed powder in pure water with a pH of 6-7 and a temperature of 20-30°C, stir and homogenize to obtain a protein solution;

[0080] Step III: Dissolve the acidic functional ingredients in purified water at 20-30°C, stir and add the protein solution, homogenize, and adjust the pH to 2.5-5 to obtain an acidic functional protein beverage.

[0081] The following examples describe the formulation and preparation method according to the present invention in detail:

[0082] Example 1: Complete Formulation (Isomaltooligosaccharide, Fructooligosaccharide and Stevioside Complex System)

[0083] This embodiment provides a highly soluble and stable protein powder containing acidic functional ingredients. The protein powder comprises the following components by mass percentage:

[0084] Element mass percentage / % Soy protein isolate 82.5 Hawthorn powder 1.2 Isomaltooligosaccharide 10 Fructooligosaccharides 6 Steviosides 0.3

[0085] Example 2: Stevioside-free control group (isomaltooligosaccharide and fructooligosaccharide compound system)

[0086] This embodiment provides a protein powder, which comprises the following components by mass percentage:

[0087]

[0088]

[0089] Example 3: Optimization experiment of the ratio of isomaltooligosaccharide and fructooligosaccharide

[0090] This embodiment provides a protein powder, which comprises the following components by mass percentage:

[0091]

[0092] Example 4: Optimization Experiment of Isomaltooligosaccharide and Fructooligosaccharide Content

[0093] This embodiment provides a protein powder, which comprises the following components by mass percentage:

[0094]

[0095] Example 5: Control group using traditional thickeners (pectin system)

[0096] This embodiment provides a protein powder, which comprises the following components by mass percentage:

[0097] Element mass percentage / % Soy protein isolate 91.8 Hawthorn powder 1.2 pectin 2 sucrose 7

[0098] Example 6: Application Expansion of Acidic Functional Protein Beverages

[0099] This embodiment uses the protein powders from Examples 1 and 5 to make an acidic functional protein beverage:

[0100] (1) According to the formula of Example 1, soy protein isolate, isomaltooligosaccharide, fructooligosaccharide and steviol glycosides were dry-mixed to obtain a mixed powder;

[0101] The mixed powder was dissolved in pure water with a pH of 6.5 and a temperature of 20°C, and stirred and homogenized to obtain a protein solution.

[0102] Hawthorn powder was dissolved in purified water at 20°C, stirred and added to the protein solution, homogenized, and the pH was adjusted to 3.8 to obtain an acidic functional protein beverage.

[0103] (2) According to the formula of Example 5, soy protein isolate, pectin powder and sucrose are dry mixed to obtain a mixed powder;

[0104] The mixed powder was dissolved in pure water with a pH of 6.5 and a temperature of 20°C, and stirred and homogenized to obtain a protein solution.

[0105] Dissolve hawthorn powder in purified water at 20°C, stir and add the protein solution, homogenize, adjust pH to 3.8, and obtain a protein beverage.

[0106] The acidic functional protein beverages prepared in Examples 1-5 were stored at 4°C for 30 days, and the precipitate was observed.

[0107] The products from Examples 1 to 6 were subjected to the following performance tests.

[0108] Performance test items:

[0109] 1. Dissolving time

[0110] Test standard: Modified according to GB / T 31742-2015 Determination of Solubility of Instant Foods

[0111] Instruments: 500ml transparent beaker (8cm inner diameter), magnetic stirrer (constant speed 300rpm), stopwatch (accuracy 0.1s)

[0112] step:

[0113] a. Pour 200ml of distilled water (20±1℃) into a beaker and start stirring;

[0114] b. Weigh 30g of protein powder sample and pour it into the center of the vortex at a constant speed within 5 seconds;

[0115] c. Start timing from the end of powder addition and stop timing when there are no visible particles or suspended clumps in the solution;

[0116] Repeat 3 times and take the average.

[0117] 2. Instantaneous sedimentation volume

[0118] Instruments: 250ml stoppered graduated cylinder (0.5ml graduation), constant temperature water bath (25±0.5℃)

[0119] step:

[0120] a. Transfer the prepared protein solution (concentration: 30g powder / 200ml water) to a graduated cylinder and bring the volume up to 250ml; b. Record the volume of the precipitate after 30 minutes at room temperature (read the lower edge of the precipitate scale);

[0121] The results are expressed as ml / 100ml (i.e., the volume of precipitate per 100ml of solution).

[0122] 3. Centrifugal sedimentation rate

[0123] Testing standard: Refer to GB / T 23528-2009 Protein Beverages

[0124] Instruments: Centrifuge (horizontal rotor), centrifuge tubes (50ml, accuracy ±0.01g)

[0125] step:

[0126] a. Take 40ml of the brewing solution (concentration as before) and put it into a centrifuge tube. Centrifuge at 4000rpm for 10 minutes.

[0127] b. Carefully pour out the supernatant and use filter paper to absorb any remaining liquid from the tube wall;

[0128] c. Weigh the wet weight of the precipitate (W) sediment );

[0129] d. Calculate the sedimentation rate;

[0130] Sedimentation rate calculation formula:

[0131]

[0132] W totalsolids = Total solids mass of the solution (measured by drying the same batch of solutions to constant weight).

[0133] 4. Solubility Index (NSI)

[0134] Testing standard: Refer to GB 5009.5-2016 "Determination of Protein in Food"

[0135] Principle: Nitrogen solubility index = (soluble protein nitrogen / total nitrogen) × 100

[0136] step:

[0137] a. Total nitrogen determination: The total nitrogen content (Ntotal) of the raw protein powder was determined by the Kjeldahl method;

[0138] b. Extraction of soluble nitrogen:

[0139] Dissolve 1g of protein powder in 50ml of pH 3.5 buffer solution and stir magnetically for 30 minutes (25℃); centrifuge at 4000rpm for 15 minutes and filter the supernatant (0.45μm membrane);

[0140] c. Determination of soluble nitrogen: The Kjeldahl method is used to determine the nitrogen content (N soluble) in the supernatant;

[0141] d. Calculate the solubility index (NSI):

[0142]

[0143] The performance test results of Examples 1 to 6 are shown in the table below:

[0144] Table 1 Performance test results of Examples 1-6

[0145]

[0146] The protein powder of the present invention, which contains acidic functional ingredients and exhibits high solubility and stability, has the following advantages:

[0147] (1) This invention significantly improves the brewing and dissolution speed and solution stability through the oligosaccharide-sweetener compound system. The dry mixing process is simple, requires no complex modification treatment, and has a lower cost than enzymatic hydrolysis or microencapsulation technology, thus having good industrialization advantages.

[0148] (2) New discovery of synergistic effect: The addition of the steviosides made the IMO / FOS system dissolve faster, with lower immediate precipitation and centrifugal precipitation rate and higher solubility index, proving that its hydrophobic anchoring effect is crucial to solubility and stability.

[0149] (3) Breakthrough in both quick dissolution and stability: For the first time, a compatibility effect of "30-second quick dissolution + 30-minute sedimentation amount ≤0.5ml / 100ml" is achieved in solid protein powder containing acidic functional ingredients. The sedimentation rate of the protein powder after brewing and dissolving is ≤4.5% after immediate centrifugation. The sedimentation rate of the acidic functional protein beverage is ≤6% after standing at 4℃ for 30 days.

[0150] (4) To address the issue of clumping during brewing, isomaltooligosaccharides and fructooligosaccharides bind to the polar groups of protein powder through hydroxyl hydrogen bonds, forming a hydration layer barrier that prevents direct contact between soy protein isolate and acidic functional components, thus delaying the sudden drop in local pH.

[0151] (5) To address the issue of isoelectric point precipitation, steviol glycosides anchor the hydrophobic regions of soy protein isolate, inhibiting hydrophobic group aggregation through surface-like effects, and synergistically constructing a "hydrogen bond-hydrophobic dual-region protective layer" with fructooligosaccharides to inhibit isoelectric point aggregation and improve system stability;

[0152] (6) To address the problem of low dissolution rate, the branched structure of isomaltooligosaccharide can produce a stereoblocking effect, blocking the hydrophobic binding of proteins, effectively reducing the viscosity of the solution, and promoting powder dispersion.

[0153] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any person skilled in the art can make many possible variations and modifications to the technical solution of the present invention, or modify it into equivalent embodiments, without departing from the scope of the present invention, using the disclosed technical means and content. Therefore, all equivalent changes made based on the shape, structure, and principle of the present invention without departing from the scope of the present invention should be covered within the protection scope of the present invention.

Claims

1. A protein powder with high solubility, high stability, and containing acidic functional ingredients, characterized in that, The protein powder comprises the following components by weight percentage: 70-92% soy protein isolate, 1-3% acidic functional ingredients, and 4.52-16.5% compound solubility-dispersion-stabilizing components.

2. The protein powder with high solubility, high stability, and acidic functional components according to claim 1, characterized in that, The composite dissolution-dispersion-stabilizing component comprises, by mass percentage, 3-10% isomaltooligosaccharide, 1.5-6% fructooligosaccharide, and 0.02-0.5% steviol glycosides.

3. The protein powder with high solubility, high stability, and acidic functional components according to claim 2, characterized in that, The isomaltooligosaccharide contains ≥50% α-1,6 glycosidic bonds, has a degree of polymerization of 3-5, a molecular weight of 500-900 Da, and ≥10 free hydroxyl groups per molecule. The branched structure ratio in isomaltooligosaccharides is: panose > isomalttriose > isomaltose, and the panose content is ≥35%.

4. The protein powder with high solubility, high stability, and acidic functional components according to claim 3, characterized in that, The oligofructose has a degree of polymerization of 2-4 accounting for >60%, a molecular weight of 300-650 Da, a purity of ≥95%, and a hydroxyl content of ≥40%.

5. The protein powder with high solubility, high stability, and acidic functional components according to claim 4, characterized in that, The stevioside contains ≥80% ribobadiin M, has a hydrophilic to hydrophobic group ratio of 4:1, and a molecular weight of 950–1000 Da.

6. The protein powder with high solubility, high stability, and acidic functional components according to claim 5, characterized in that, At 20℃, based on a ratio of 30g powder / 200ml water, the dissolving time of the protein powder is ≤30 seconds; The amount of sediment in the protein powder preparation solution after standing for 30 minutes is ≤0.5ml / 100ml; The instant centrifugation sedimentation rate of the protein powder preparation solution is ≤4.5%; The solubility index of the protein powder in the brewing solution is ≥80%.

7. The protein powder with high solubility, high stability, and acidic functional components according to claim 6, characterized in that, The acidic functional ingredient is at least one of the following: hawthorn powder, jujube powder, sour cherry powder, lemon powder, dried plum powder, schisandra powder, cornus powder, malic acid powder, or yogurt powder containing probiotics.

8. A method for preparing a protein powder with high solubility, high stability, and containing acidic functional components, characterized in that, The preparation method is used to prepare protein powder with high solubility, high stability, and acidic functional components as described in any one of claims 1 to 7; The preparation method includes the following steps: Step 1: Mix the acidic functional ingredients, fructooligosaccharides, and steviol glycosides for 10 minutes to obtain a premix. Step 2: Add soy protein isolate and isomaltooligosaccharide to the premix and mix for 20 minutes to obtain a protein powder with high solubility, high stability and acidic functional components.

9. An acidic functional protein beverage, characterized in that, The protein beverage includes protein powder with high solubility, high stability, and acidic functional ingredients as described in any one of claims 1 to 7; The pH of the protein beverage is 2.5–5; The protein beverage had a centrifugal sedimentation rate of ≤6% after standing at 4°C for 30 days. The solubility index of the protein beverage after standing at 4°C for 30 days is ≥75%.

10. A method for preparing an acidic functional protein beverage, characterized in that, The preparation method is used to prepare the acidic functional protein beverage as described in claim 9; The preparation method includes: Step I: Dry mix soy protein isolate, isomaltooligosaccharide, fructooligosaccharide and steviol glycosides to obtain a mixed powder; Step II: Dissolve the mixed powder in pure water with a pH of 6-7 and a temperature of 20-30°C, stir and homogenize to obtain a protein solution; Step III: Dissolve the acidic functional ingredients in purified water at 20-30°C, stir and add the protein solution, homogenize, and adjust the pH to 2.5-5 to obtain an acidic functional protein beverage.

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