Boletus aereus polysaccharide-whey protein isolate composite gel and preparation method thereof

Abstract

The invention belongs to the field of food hydrophilic colloids, and particularly relates to boletus aereus polysaccharide-whey protein isolate composite gel and a preparation method thereof, and the boletus aereus polysaccharide-whey protein isolate composite gel is formed by boletus aereus polysaccharide and whey protein isolate through thermal induction treatment. The boletus aereus polysaccharide is utilized to promote the whey protein isolate to form the composite gel with adjustable gel characteristics, different eating requirements can be met, the nutritional value of the boletus aereus polysaccharide can be effectively reserved, and the market blank of the boletus aereus polysaccharide gel is filled.

Description

Technical Field

[0001] The present application belongs to the field of food hydrophilic colloids, and specifically relates to a Boletus edulis polysaccharide-whey protein isolate composite gel and a preparation method thereof. Background Art

[0002] Whey protein isolate (WPI) is a protein obtained by further separation and concentration of whey, a byproduct of cheese production. It mainly consists of α-lactalbumin (25%), β-lactoglobulin (65%) and a small amount of glycomacropeptide, lactoferrin, immunoglobulin, bovine serum albumin, etc. It has high nutritional value and a variety of amino acids. It also has biological activities such as antiviral, blood pressure lowering, cholesterol lowering, antibacterial, antioxidant, and anticancer. In addition, whey protein isolate also has a variety of functional properties, gelation is one of the most important functions. β-lactoglobulin and bovine serum albumin in whey protein isolate are the two main gelling proteins. After heating denaturation aggregation and cooling with an ice water bath, they can form heat-induced gels. The gelation of whey protein isolate is determined by factors such as protein concentration, pH value, ionic strength, type and concentration of polysaccharides. Polysaccharides can combine with whey protein isolate during heating to form polymers, promoting the formation of network gels. Different types of polysaccharides can form different types of polymer gels with proteins, such as combined, mosaic, and phase-separated types.

[0003] Boletus aereus Fr. ex Bull. is a precious edible mushroom with rich nutritional value. Studies have found that Boletus aereus Fr. ex Bull. contains a variety of bioactive substances, among which polysaccharides, polyphenols and proteins are identified as the main active ingredients. In recent years, through the analysis of Boletus aereus polysaccharides (BAP), it was found that Boletus aereus polysaccharides have certain biological activities in anti-tumor, anti-inflammatory, antioxidant, immunomodulatory and hypolipidemic aspects, and are a bioactive ingredient with great medicinal value. However, there is no relevant research on the effect of Boletus aereus polysaccharides on the gelation of whey protein isolate.

[0004] Therefore, it is necessary to clarify the effect of Boletus edulis polysaccharide on the gelation of whey protein isolate, so as to provide a composite gel with Boletus edulis polysaccharide as one of the raw materials to fill the market gap of Boletus edulis polysaccharide gel. Summary of the invention

[0005] The problem that the present application aims to solve is to provide a black boletus polysaccharide-whey protein isolate composite gel and a preparation method thereof, and to utilize black boletus polysaccharide to promote whey protein isolate to form a composite gel with adjustable gel properties, which can meet different edible needs and can effectively retain the nutritional value of black boletus polysaccharide.

[0006] In order to solve the above technical problems, this application adopts the following technical solutions:

[0007] In one aspect, the present application provides a Boletus edulis polysaccharide-whey protein isolate composite gel, wherein the Boletus edulis polysaccharide-whey protein isolate composite gel is formed by subjecting Boletus edulis polysaccharide and whey protein isolate to heat-induced treatment.

[0008] In the above technical solution, Boletus edulis polysaccharide can promote cross-linking between whey protein isolates during heating and fill the gaps between the gel structures of whey protein isolates to form a protein gel network structure with a large aggregation area, making the structure denser.

[0009] Furthermore, the weight ratio of the Boletus edulis polysaccharide to the whey protein isolate is 1.5 to 3:10.

[0010] In the above technical solution, the formation of a composite gel can be ensured by limiting the weight ratio of Boletus edulis polysaccharide to whey protein isolate, and by adjusting within this weight ratio range, composite gels with different gel properties can be obtained.

[0011] Furthermore, the method adopted by the thermal induction treatment includes water bath heating.

[0012] In the above technical solution, water bath heating can more accurately control the heating temperature, thereby avoiding temperature fluctuations or uneven heating of whey protein isolate, which may lead to incomplete protein denaturation or uneven gel formation.

[0013] Furthermore, the water bath heating temperature is 80° C. to 95° C., and the water bath heating time is 10 to 30 minutes.

[0014] In the above technical solution, controlling the temperature and time of water bath heating can ensure that Boletus edulis polysaccharide and whey protein isolate form a stable and dense gel structure.

[0015] On the other hand, the present application provides a method for preparing the above-mentioned Boletus edulis polysaccharide-whey protein isolate composite gel, comprising the following steps:

[0016] A black boletus polysaccharide solution is prepared; a whey protein isolate solution is prepared; and the black boletus polysaccharide solution and the whey protein isolate solution are mixed, the pH value is adjusted, magnetic stirring is performed, heat induction treatment is performed, and finally low-temperature treatment is performed to obtain the black boletus polysaccharide-whey protein isolate composite gel.

[0017] Furthermore, the concentration ratio of the Boletus edulis polysaccharide solution to the whey protein isolate solution is 1.5 to 3:10.

[0018] In the above technical solution, the concentration ratio of the Boletus edulis polysaccharide solution and the whey protein isolate solution is limited, which can ensure that a dense gel structure is finally formed.

[0019] Furthermore, the pH is adjusted to a range of 6.9 to 7.1.

[0020] In the above technical solution, when the pH is 6.9-7.1, the mutual repulsion between the particles of the Boletus edulis polysaccharide-whey protein isolate composite gel is relatively large, which can ensure that the composite gel has a more stable system.

[0021] Furthermore, the temperature of the low temperature treatment is 4°C, and the time of the low temperature treatment is 20 hours.

[0022] In another aspect, the present application provides applications of the above-mentioned Boletus edulis polysaccharide-whey protein isolate composite gel or the Boletus edulis polysaccharide-whey protein isolate composite gel obtained by the above-mentioned method, including applications in food.

[0023] This application has the following beneficial effects:

[0024] 1. The present application utilizes Boletus edulis polysaccharide to promote the cross-linking between whey protein isolates and serves as a filler in the gaps between the gels, thereby ultimately improving the density and strength of the gel.

[0025] 2. This application combines Boletus edulis polysaccharide with whey protein isolate for the first time to obtain a composite gel with adjustable gel properties, and the gel has good water retention, rheological properties and thermal stability.

[0026] 3. The steps for preparing the black boletus polysaccharide-whey protein isolate composite gel in the present application are simple, and a nutritious composite gel food with excellent sensory characteristics can be obtained without adding other ingredients, which provides a new idea for the development of black boletus food. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The macroscopic appearance of BAP-WPI composite gels with different BAP concentrations prepared in Example 4 of the present application;

[0028] Figure 2 This is a bar graph of the water holding capacity of the BAP-WPI composite gel under different BAP addition conditions in this application;

[0029] Figure 3 The linear viscoelastic region of the BAP-WPI composite gel under different BAP addition conditions in this application (a: storage modulus; b: loss modulus);

[0030] Figure 4 The static shear data and Powerlaw equation fitting of BAP-WPI composite gel under different BAP addition conditions in this application (a: shear stress; b: right viscosity; c: Power law equation fitting);

[0031] Figure 5 The dynamic frequency scanning results of BAP-WPI composite gel under different BAP addition conditions in this application (a: G', G"; b: tanδ);

[0032] Figure 6 The various texture indicators of BAP-WPI composite gel under different BAP addition conditions in this application;

[0033] Figure 7 This is the change of thermal enthalpy value of BAP-WPI composite gel under different BAP addition conditions in this application;

[0034] Figure 8 The water migration and distribution characteristics of BAP-WPI composite gel under different BAP addition conditions in this application;

[0035] Fig. 9 XRD patterns of BAP-WPI composite gel under different BAP addition conditions in this application;

[0036] Fig.10 Infrared spectra of BAP, WPI and BAP-WPI composite gel under different BAP addition conditions of the present application (a: infrared spectra of BAP, WPI and BAP-WPI composite gel; b: infrared spectra of BAP-WPI composite gel under different BAP addition conditions);

[0037] Fig.11 The turbidity of BAP-WPI composite gel under different BAP addition conditions in this application;

[0038] Fig.12 Zeta potential of different systems in this application (a: different pH; b: different BAP concentration);

[0039] Fig.13 The average Zeta potential, average particle size and polydispersity index of BAP-WPI composite gel under different BAP addition conditions in this application;

[0040] Fig.14 This is the electron microscope scanning image of the BAP-WPI composite gel under different BAP addition conditions in this application. DETAILED DESCRIPTION

[0041] The technical solutions in some embodiments of the present application are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments provided by the present application, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present application.

[0042] Example 1 Extraction of Boletus edulis polysaccharide

[0043] Select fresh black boletus samples to remove root mud and some inedible tissues, wash them with tap water, rinse them with ultrapure water, then slice the black boletus fruiting bodies, dry them at 50°C and grind them into powder, pass them through an 80-mesh sieve, collect and sieve out the powder, add a 95% ethanol solution with a volume fraction at a solid-liquid ratio (g:mL) of 1:10, soak for 12 hours, and then filter. Repeat the soaking and filtration operations twice to remove fat-soluble substances, free phenolic acids, and small molecular monosaccharides and disaccharides, and then centrifuge them at a speed of 5000r / min for 10 minutes. After centrifugation, dry the precipitate at 50°C to constant weight. Using the hot water extraction method, the dried precipitate was added to 85°C ultrapure water at a solid-liquid ratio of 1:20 g / mL, and the extraction was maintained at 85°C for 4 hours to obtain a polysaccharide extract, which was then centrifuged at 5000 r / min for 10 minutes. The supernatant was filtered and collected. After repeating the extraction, centrifugation, filtration and collection operations twice, the supernatants were combined and vacuum concentrated at 50°C until the volume of the polysaccharide extract was reduced to 1 / 4 of the original volume to obtain a concentrated polysaccharide extract. Add pancreatic enzyme with an enzyme activity of 5U / mL to the concentrated polysaccharide extract, place in a water bath at 40°C for 8 hours to remove the protein, then inactivate at 95°C for 30 minutes, and then centrifuge at 5000r / min for 10 minutes. Take the supernatant and slowly add anhydrous ethanol until the ethanol volume ratio reaches 80%, then let it stand at 4°C for 12 hours, and then centrifuge at 5000r / min for 15 minutes. After centrifugation, use ultrapure water to re-dissolve the precipitate, and then dialyze in a 3500Da dialysis bag for 48 hours, and then vacuum freeze-dry to obtain black boletus polysaccharide (BAP).

[0044] Example 2 Preparation of BAP solution

[0045] 3 g of BAP prepared in Example 1 was dispersed in 50 mL of ultrapure water, stirred continuously at 500 r / min for 2 h using a magnetic stirrer at room temperature, and then stored in a refrigerator at 4° C. overnight to ensure that the BAP was completely dissolved, to obtain a BAP solution with a concentration of 6% (the concentrations of BAP and WPI herein and in the following text are both weight to volume).

[0046] Example 3 Preparation of whey protein isolate (WPI) solution

[0047] 20 g of WPI powder was dispersed in 100 mL of ultrapure water, stirred continuously at 500 r / min for 2 h using a magnetic stirrer at room temperature, and then stored in a refrigerator at 4° C. overnight to ensure that the WPI was fully hydrated, to obtain a WPI solution with a concentration of 20%.

[0048] Example 4 Preparation of BAP-WPI composite gels of different concentrations

[0049] The BAP solution in Example 2 and the WPI solution in Example 3 were diluted in a certain proportion and mixed, so that the final concentrations of the BAP solution in the mixed solution were 1.5%, 2%, 2.5%, 2.75%, and 3%, respectively, and the final concentration of the WPI solution was 10%. 1M NaOH was added to each mixed solution until the pH was 7, and then magnetic stirring was performed. Then, each mixed solution was heated at 95°C for 30 minutes in a water bath, and then cooled to room temperature in an ice water bath, and then placed in a refrigerator at 4°C for 20 hours to obtain BAP-WPI composite gels of different concentrations, such as Figure 1 shown.

[0050] according to Figure 1 It can be seen that when the final concentration of the BAP solution is 2% to 3%, the composite gel has a good macroscopic morphology. When the final concentration of the BAP solution is 1.5%, the obtained composite gel is relatively soft but still has an obvious gel state.

[0051] Comparative Example 1 Preparation of WPI Gel

[0052] The WPI solution in Example 3 was diluted to a concentration of 10%, and then 1 M NaOH was added until the pH was 7, followed by magnetic stirring. The mixed solutions were then heated at 95° C. for 30 min in a water bath, cooled to room temperature in an ice-water bath, and placed in a refrigerator at 4° C. for 20 h to obtain a WPI gel.

[0053] Experimental Example 1 Water Holding Characteristics Test

[0054] The water holding capacity (WHC) of each BAP-WPI composite gel prepared in Example 4 and the WPI gel prepared in Comparative Example 1 was determined by centrifugation: 2 g of the composite gel sample was accurately weighed, carefully wrapped with double-layer filter paper, and placed in a 50 mL centrifuge tube. The sample was centrifuged at 10,000 r / min for 15 min in an environment of 4° C. After the centrifugation, the free water on the surface of the gel was carefully absorbed with filter paper, and the water holding capacity was calculated according to the following formula. The data were collected and sorted to obtain: Figure 2 As shown:

[0055]

[0056] Where: m0——total mass of gel sample after centrifugation (m);

[0057] m1——Total mass of gel sample before centrifugation (m).

[0058] Experimental Example 2 Rheological Properties

[0059] Each BAP-WPI composite gel prepared in Example 4 was placed at room temperature for 30 minutes, and after the state was stable, it was carefully moved to the stage of the rheometer (MCR302e), and then the parallel plates were controlled to slowly press down. During the operation, it was noted to remove excess sample to ensure that the sample state met the test requirements. Then the linear viscoelastic region, apparent viscosity and dynamic viscoelasticity were measured in turn.

[0060] (1) Linear viscoelastic region measurement (LVR)

[0061] By observing the changes in the strain and storage modulus (G') of the sample, the linear viscoelastic region of the sample is determined, and then the appropriate deformation amount in this region is selected for the subsequent dynamic viscoelasticity measurement.

[0062] The following parameters were used for the measurement: parallel plates with a diameter of 50 / 40 mm were used, the spacing was set to 0.5 mm, the frequency was set to 1 Hz, and the strain range was controlled between 0.1% and 100%. For each sample, three parallel measurements were performed, and the average value of the results was finally taken to ensure the reliability and accuracy of the data. The results are shown in the figure below. Figure 3 shown.

[0063] (2) Apparent viscosity measurement

[0064] At room temperature, the apparent viscosity of the sample was measured as a function of shear rate. The specific measurement parameters are as follows: a parallel plate with a diameter of 40 mm was selected, the slit spacing was set to 0.5 mm, and the shear rate range was set to 0.01 to 1000 s-1. To ensure the reliability of the experimental data, each sample was measured three times in parallel, and the final result was the average of the three measurement data. The results are shown in the figure below. Figure 4 shown.

[0065] (3) Dynamic viscoelasticity measurement

[0066] The frequency scanning experiment of the sample was carried out in oscillation mode. The specific experimental parameters were set as follows: the deformation was determined based on the measurement results of the linear viscoelastic zone, the frequency range was set to 0.1-100 rad / s, and the storage modulus (G'), loss modulus (G") and loss factor (tanδ=G" / G') of the composite gel were measured with angular frequency under a constant temperature of 25℃, so as to obtain the relevant mechanical properties data of the composite gel under different angular frequencies under this condition. The results are shown in Figure 5 shown.

[0067] Experimental Example 3 Texture Characteristics

[0068] Prepare the BAP-WPI composite gel in a 10 mL beaker according to the method of Example 4, ensuring that its loading volume is not less than 4 mL. After the preparation is completed, the composite gel is placed in a room temperature environment for equilibrium for 30 minutes. After its state is stable, the TPA test is carried out using a TA-XTPlusC texture analyzer. The test uses a P / 0.5S spherical probe, and the specific parameters are set as follows: the pre-test speed is set to 1.0 mm / s, the speed during the test is controlled at 2.0 mm / s, the post-test speed is 10.0 mm / s, the compression degree is set to 40%, the trigger force is 3g, the interval between two compressions is 5s, and the trigger type is selected as automatic. After the test, the obtained data is analyzed in detail with the help of the texture analyzer analysis software to obtain various gel indicators such as hardness, elasticity, viscosity, and adhesion. The results are as follows Figure 6 shown.

[0069] according to Figure 6 It can be seen that by adjusting the content of BAP, BAP-WPI composite gels with different texture properties such as hardness, elasticity, and viscosity can be obtained.

[0070] Experimental Example 4 Thermal Stability (DSC)

[0071] Weigh 5 mg of freeze-dried sample powder of each BAP-WPI composite gel prepared in Example 4 and the WPI gel prepared in Comparative Example 1, and carefully place them in an aluminum crucible. At the same time, take a blank crucible as a control sample. During the experiment, nitrogen was selected as the carrier gas, and the purge gas flow rate was set to 20 mL / min. The sample was gradually heated from 30°C to 150°C at a heating rate of 5°C / min. During the entire heating process, professional equipment was used to accurately record the changes in the thermal enthalpy of the gel sample. The results are shown in Figure 2. Figure 7 shown.

[0072] according to Figure 7 It can be seen that the BAP-WPI composite gel prepared in the present application obviously has better thermal stability.

[0073] Experimental Example 5 Low Field Nuclear Magnetic Resonance Proton Spectroscopy (LF-NMR)

[0074] The water migration and distribution characteristics of each BAP-WPI composite gel prepared in Example 4 were tested using a low-field nuclear magnetic resonance analyzer. Accurately weigh about 2 g of gel sample and carefully place it in a 25 mm nuclear magnetic glass tube. The test uses a CPMG (Carr-Purcell-Meiboom-Gill) pulse sequence. Before the test, the instrument was calibrated using the free induction decay signal (FID) mode to ensure data accuracy. The acquisition parameters of the transverse relaxation time T2 were set strictly in accordance with the instrument manual: the sampling frequency was set to 250 kHz, the number of sampling points was 375020s, and the number of accumulations was set to 8 times. After the test is completed, data is collected with the help of nuclear magnetic resonance analysis software, and the collected data is processed and analyzed using the mass normalization method. The results are as follows Figure 8 shown.

[0075] Experimental Example 6: XRD Diffraction Measurement of Crystallinity

[0076] Take appropriate amounts of 2% BAP, 10% WPI, and the BAP-WPI composite gel sample with a BAP content of 2% obtained in Example 4, and use an X-ray diffractometer to measure the crystallinity at room temperature. The specific experimental parameters are set as follows: the scanning range of 2θ is set to 5-60°, the scanning speed is controlled at 1° / min, and the step size is set to 0.02θ. After the scan is completed, the crystallization peak area and the total diffraction area are obtained by integral calculation, and the ratio of the crystalline region area to the total area is used as the relative crystallinity to characterize the degree of crystallinity of the sample. The results are as follows: Fig. 9 shown.

[0077] Experimental Example 7 Fourier Transform Infrared Spectroscopy Detection

[0078] 1 mg of BAP, WPI and the freeze-dried sample powder of the BAP-WPI composite gel with a BAP content of 2% prepared in Example 4 were accurately weighed and placed in an agate mortar. The sample powders were fully mixed with KBr at a ratio of 1:100. Under an infrared lamp, the mixture was continuously ground in a mortar until it became a fine powder.

[0079] Subsequently, the ground fine powder was prepared into a uniform and transparent thin sheet with the help of a tablet press. After the sample thin sheet was prepared, it was placed in an infrared spectrometer and scanned in the wave number range of 4000cm-1 to 400cm-1. The number of scans was set to 64 and the resolution was set to 4cm-1 to obtain accurate infrared spectrum data. The results are as follows: Fig.10 shown.

[0080] Experimental Example 8 Determination of turbidity

[0081] 2.8 Turbidity determination

[0082] The BAP solution in Example 2 and the WPI solution in Example 3 were diluted in a certain proportion and mixed, so that the final concentrations of the BAP solution in the mixed solution were 1.5%, 2%, 2.5%, 2.75%, and 3%, respectively, and the final concentration of the WPI solution was 10%; another group was set up, without adding BAP solution, and only the WPI solution was diluted to 10%. Each group measured 1mL of the mixed solution and diluted it to a protein concentration of 1mg / mL. Then, the obtained 1mg / mL protein solution was placed in a constant temperature water bath at 95℃ and heated for 30min. After heating, it was allowed to cool naturally to room temperature and then placed in a refrigerator at -4℃ and left to stand overnight.

[0083] After the treatment is completed, use an ultraviolet spectrophotometer to measure the absorbance of the solution at a wavelength of 600nm to record the turbidity. The results are as follows: Fig.11 shown.

[0084] Experimental Example 9 Determination of Zeta Potential

[0085] Take appropriate amounts of 2% BAP, 10% WPI, and freeze-dried samples of the BAP-WPI composite gel with a BAP content of 2% obtained in Example 4. Use distilled water to dissolve the above samples and prepare a solution with a concentration of 0.1%. With the help of a pH regulator, the pH value of the solution is accurately adjusted to 2, 3, 4, 5, 6, and 7, respectively, for subsequent determination of the Zeta potential of samples at different pH values. Take an appropriate amount of BAP-WPI composite gel sample, dilute it with distilled water to a concentration of 1 mg protein / mL, and measure the Zeta potential of the gel samples prepared under different pH treatments.

[0086] Take appropriate amounts of freeze-dried samples of each BAP-WPI composite gel prepared in Example 4 and the WPI gel prepared in Comparative Example 1, dissolve the samples in distilled water to prepare a solution with a concentration of 0.1%, and take 800 μL of the solution to measure the Zeta potential of the BAP-WPI composite gels prepared with different BAP concentrations.

[0087] Parameter setting: In the particle size potential analyzer, select protein as the material and water as the dispersant. Use a pipette to accurately draw 800μL of the diluted sample solution and slowly inject it into the Zeta potential measurement sample pool. Place the sample pool in a 25℃ environment for 30s to balance, and start the measurement program after the sample state stabilizes. After the measurement is completed, use the analysis software that comes with the particle size potential analyzer to process and analyze the data, and finally obtain the average Zeta potential (mV) of different systems. The results are as follows: Fig.12 shown.

[0088] Experimental Example 10 Determination of particle size

[0089] Take appropriate amounts of freeze-dried samples of each BAP-WPI composite gel prepared in Example 4 and WPI gel prepared in Comparative Example 1, dissolve the above samples in distilled water, prepare a solution with a concentration of 0.1%, and then take 1 mL of the sample solution to measure the particle size. All were measured after equilibration at 25°C for 30 seconds, and the data were analyzed using the instrument's own software to obtain the average particle size and polydispersity index (PDI). The results are as follows: Fig.13 shown.

[0090] Experimental Example 11 Scanning Electron Microscope

[0091] Each BAP-WPI composite gel prepared in Example 4 and the WPI gel sample prepared in Comparative Example 1 was immersed in liquid nitrogen for freeze-crushing, and then vacuum cooled and dried. Before observation with a scanning electron microscope, the dried samples were manually broken and fixed on a cylindrical stage with conductive glue, and gold was sprayed for 45 seconds using an Oxford Quorum SC7620 sputtering coater. The sample morphology was photographed and its microstructure was observed using a ZEISSGeminiSEM 300 scanning electron microscope (×2000, ×4000). The results are shown in FIG. Fig.14 shown.

[0092] It can be seen from the electron microscopy image that when BAP is not added, the WPI gel has a uniform porous gel structure; after adding BAP, BAP fills the gaps in the WPI gel structure, causing the gel structure to form aggregated areas, and the structure becomes uneven but dense.

[0093] The above is only a preferred embodiment of the present application. It should be understood that the present application is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge in the relevant field. The changes and modifications made by those skilled in the art shall not deviate from the spirit and scope of the present application, and shall be within the scope of protection of the claims attached to the present application.

Claims

1. Boletus edulis polysaccharide-whey protein isolate composite gel, characterized in that: The black boletus polysaccharide-whey protein isolate composite gel is formed by subjecting black boletus polysaccharide and whey protein isolate to heat induction treatment.

2. The Boletus edulis polysaccharide-whey protein isolate composite gel according to claim 1, characterized in that: The weight ratio of the black boletus polysaccharide to the whey protein isolate is 1.5 to 3:

10.

3. The Boletus edulis polysaccharide-whey protein isolate composite gel according to claim 1, characterized in that: The method adopted by the heat-induced treatment includes water bath heating.

4. The Boletus edulis polysaccharide-whey protein isolate composite gel according to claim 3, characterized in that: The water bath heating temperature is 80° C. to 95° C., and the water bath heating time is 10 to 30 minutes.

5. A method for preparing the Boletus edulis polysaccharide-whey protein isolate composite gel according to any one of claims 1 to 4, characterized in that: The following steps are involved: preparing a black boletus polysaccharide solution; preparing a whey protein isolate solution; as well as The black boletus polysaccharide solution and the whey protein isolate solution are mixed, the pH is adjusted, and then stirred, and then heat-induced treatment is performed, and finally low-temperature treatment is performed to obtain the black boletus polysaccharide-whey protein isolate composite gel.

6. The method according to claim 5, characterized in that The concentration ratio of the black boletus polysaccharide solution to the whey protein isolate solution is 1.5 to 3:

10.

7. The method according to claim 5, characterized in that The pH is adjusted in the range of 6.9 to 7.

1.

8. The method according to claim 5, characterized in that The temperature of the low temperature treatment is 4°C, and the time of the low temperature treatment is 20 hours.

9. Use of the Boletus edulis polysaccharide-whey protein isolate composite gel according to any one of claims 1 to 4 or the Boletus edulis polysaccharide-whey protein isolate composite gel prepared by the method according to any one of claims 5 to 8, characterized in that: Including applications in food.

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