A kind of alcohol-soluble protein-milk protein composite hollow particle and its preparation method and application

Abstract

The present invention relates to a kind of alcohol-soluble protein-milk protein composite hollow particles and a preparation method and application thereof, belonging to the field of food technology. In the alcohol-soluble protein-milk protein composite hollow particles of the present invention, alcohol-soluble protein and milk protein are covalently cross-linked to form two kinds of protein mixed shells. The present invention selects alcohol-soluble protein and milk protein as shell materials, and performs alkaline heating treatment on the ethanol solutions of the two, so that covalent action occurs between alcohol-soluble protein and milk protein to form a mixed shell structure, which on the one hand regulates the hydrophilicity and hydrophobicity of the shell, and on the other hand is conducive to the stabilization of the shell formation; improves the water dispersibility and stability of alcohol-soluble protein-milk protein composite hollow particles. On this basis, a hydrophobic functional factor is added to the composite solution of alcohol-soluble protein and milk protein after alkaline heating treatment, and alcohol-soluble protein-milk protein composite hollow particles loaded with hydrophobic functional factors are prepared, so as to achieve efficient embedding of the hydrophobic functional factors.

Description

Technical Field

[0001] The invention belongs to the field of food technology, and in particular relates to alcohol-soluble protein-milk protein composite hollow particles and a preparation method and application thereof. Background Art

[0002] Functional factors, including fat-soluble vitamins and phenolic compounds, have biological activities that are beneficial to health. However, they are sensitive to environmental factors such as oxygen, light and temperature. Functional factors have poor stability, poor solubility and low bioavailability, which limits their application in food. Studies have shown that encapsulation of functional factors is the key to their application in food and functional food.

[0003] In recent years, the preparation of hollow particles has received increasing attention. Compared with solid particles, hollow particles have the advantages of high specific surface area, low density, high loading and sustained release, and are used in bionics, biology, energy, environment and other related fields. Compared with inorganic hollow particles, protein-based hollow particles are beneficial for their application in the field of food and functional food due to their biodegradability and biocompatibility.

[0004] Prolamin is a storage protein extracted from grains. Prolamin hollow particles are usually prepared using inorganic salts as sacrificial templates. Since zein contains more than 50% hydrophobic amino acids and its isoelectric point is about pH 6, these make zein hollow particles stable under neutral conditions, but have poor dispersion performance.

[0005] In the prior art, water-soluble protein / polysaccharide physical coating is usually used to improve the solution dispersibility and stability of alcohol-soluble protein particles; however, the non-covalent binding between molecules can still be destroyed by environmental factors. Summary of the invention

[0006] In the prior art, alcohol-soluble protein hollow particles have problems such as poor stability and poor water dispersibility. The present invention provides alcohol-soluble protein-milk protein composite hollow particles and a preparation method and application thereof. The present invention selects alcohol-soluble protein and milk protein as shell materials, and performs alkaline heating treatment on the ethanol solutions of the two, so that covalent interaction occurs between alcohol-soluble protein and milk protein to form a mixed shell structure, which on the one hand regulates the hydrophilicity-hydrophobicity of the shell, and on the other hand is conducive to the stabilization of the shell; improves the water dispersibility and stability of alcohol-soluble protein-milk protein composite hollow particles. On this basis, a hydrophobic functional factor is added to the composite solution of alcohol-soluble protein and milk protein after alkaline heating treatment to prepare alcohol-soluble protein-milk protein composite hollow particles loaded with hydrophobic functional factors, thereby achieving efficient encapsulation of the hydrophobic functional factors.

[0007] The first object of the present invention is to provide a prolamin-milk protein composite hollow particle, wherein the prolamin and the milk protein are covalently cross-linked to form a mixed shell of two proteins.

[0008] In one embodiment, the mass ratio of the alcohol-soluble protein to the milk protein is 10-15:2.5-5; preferably 10:5.

[0009] The second object of the present invention is to provide a method for preparing alcohol-soluble protein-milk protein composite hollow particles, the method comprising the following steps:

[0010] (1) mixing an alcohol solution of prolamin and an alcohol solution of milk protein, adjusting the pH to alkaline, heating at 70 to 95° C., and then cooling to room temperature to obtain a prolamin-milk protein composite alcohol solution;

[0011] (2) mixing the alcohol solution of the sacrificial template with the alcohol solution of the alcohol-soluble protein-milk protein composite prepared in step (1); then, transferring the mixed solution to the aqueous phase and stirring evenly to obtain the alcohol-soluble protein-milk protein composite hollow particles.

[0012] (3) The pH of the alcohol-soluble protein-milk protein composite hollow particle solution obtained in step (2) is adjusted to 6 to 8 to obtain neutral alcohol-soluble protein-milk protein composite hollow particles.

[0013] In one embodiment, the heating treatment time in step (1) is 20 to 30 minutes.

[0014] In one embodiment, the step (1) of adjusting the pH to alkaline is adjusting the pH to 10-11.

[0015] In one embodiment, the alcohol solution in step (1) is an ethanol aqueous solution with a volume fraction of 60 to 80%.

[0016] In one embodiment, the alcohol-soluble protein in step (1) includes one or more of zein, kafirin, wheat alcohol-soluble protein and hordein; and the milk protein is whey protein and / or casein.

[0017] In one embodiment, the mass concentration of prolamin in the prolamin alcohol solution in step (1) is 10-15%; the mass concentration of lactoprotein in the lactoprotein alcohol solution is 2.5-5%.

[0018] In one embodiment, the mixing volume ratio of the alcohol solution of prolamin and the alcohol solution of lactoprotein in step (1) is 1:1.

[0019] In one embodiment, the pH is adjusted in step (1) using NaOH.

[0020] In one embodiment, the alcohol solution of the sacrificial template in step (2) is an ethanol solution of sodium carbonate; the mass concentration of sodium carbonate in the ethanol solution of sodium carbonate is 10-15 mg / mL; specifically, it is obtained by dissolving sodium carbonate in an ethanol solution with a volume fraction of 70%.

[0021] In one embodiment, the volume ratio of the sodium carbonate ethanol solution and the prolamin-milk protein complex alcohol solution mixed in step (2) is 1:1.

[0022] In one embodiment, the aqueous phase in step (2) is ultrapure water, and the volume ratio of the mixed solution of ultrapure water, sodium carbonate ethanol solution and prolamin-milk protein complex alcohol solution is 4:1.

[0023] In one embodiment, the uniform stirring in step (2) is performed at 1000-2000 rpm for 10-20 min.

[0024] In one embodiment, the pH value of the prolamin-milk protein composite hollow particles obtained in step (2) is 10-11.

[0025] In one embodiment, the mass ratio of the sacrificial template to the prolamin-milk protein complex is 0.06:0.5-1.5.

[0026] In one embodiment, the transfer to the aqueous phase in step (2) is achieved by anti-solvent precipitation.

[0027] The third object of the present invention is to provide an application of the above-mentioned alcohol-soluble protein-milk protein composite hollow particles in the preparation of food, health care products, or cosmetics.

[0028] In one embodiment, the application is to use alcohol-soluble protein-milk protein composite hollow particles for the embedding of hydrophobic functional factors, specifically, the hydrophobic functional factors are added to the alcohol-soluble protein-milk protein composite alcohol solution, and then mixed with the ethanol solution of the sacrificial template sodium carbonate; then the mixed solution is transferred to the aqueous phase and stirred evenly to obtain alcohol-soluble protein-milk protein composite hollow particles loaded with hydrophobic functional factors.

[0029] In one embodiment, the hydrophobic functional factor comprises one or more of curcumin, resveratrol, quercetin α-tocopherol and retinol.

[0030] In one embodiment, the mass ratio of the hydrophobic functional factor to the alcohol-soluble protein is 0.1-0.2:1.

[0031] [Beneficial Effects]

[0032] The above technical solution of the present invention has the following advantages compared with the prior art:

[0033] (1) The alcohol-soluble protein-milk protein composite hollow particles prepared by the present invention are more stable under neutral pH conditions compared with alcohol-soluble protein hollow particles alone. Among them, the alcohol-soluble protein-milk protein composite hollow particles prepared by alkali heat treatment have disulfide bonds, hydrogen bonds and hydrophobic interactions generated between alcohol-soluble protein and milk protein, which improve the stability of the composite alcohol-soluble protein nanoparticles.

[0034] (2) The alcohol-soluble protein-milk protein composite hollow particles prepared by the present invention have good storage stability. The particle size of the alcohol-soluble protein-milk protein composite hollow particles remains substantially unchanged after being stored at 45° C. for 21 days.

[0035] (3) The alcohol-soluble protein-milk protein composite hollow particles prepared by the present invention can effectively encapsulate hydrophobic functional factors. Under neutral conditions, when the mass ratio of curcumin to alcohol-soluble protein is 1:0.1 and 1:0.2, the encapsulation rates are 88% and 81%, respectively, and the loading amounts are 6.20 and 11.40 g / 100 g, respectively. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The appearance diagram (A) and the soluble protein ratio data diagram (B) of the protein hollow particles prepared in Examples 1 to 2 of the present invention and Comparative Examples 1 to 2 under pH 11 and pH 7 conditions;

[0037] Figure 2 The particle size distribution diagram (A) and ζ-potential diagram (B) of the protein hollow particles prepared in Examples 1 to 2 of the present invention and Comparative Example 1 at pH 11 and pH 7;

[0038] Figure 3 This is a transmission electron microscopy image of the zein-milk protein composite hollow particles prepared in Example 2 of the present invention at pH 7;

[0039] Figure 4 Non-reducing (A) and reducing (B) SDS-PAGE images of zein, whey protein isolate, and zein-milk protein composite hollow particles without (-) and with (+) alkaline heat treatment;

[0040] Figure 5 The data diagram is a ratio (I1 / I3) of the first band and the third band of the fluorescence spectrum of the protein hollow particles prepared in Examples 1 to 2 of the present invention and Comparative Example 1 at different concentrations of pyrene probe;

[0041] Figure 6 The particle size distribution diagram (A) and ζ-potential diagram (B) of the zein-milk protein composite hollow particles prepared in Example 2 of the present invention when the pH value is 7 and stored in an incubator at 45° C. for 28 days. DETAILED DESCRIPTION

[0042] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0043] 1. Determination of soluble protein ratio

[0044] The sample was centrifuged at 2000 × g for 15 minutes to remove large aggregates and precipitates, freeze-dried and weighed, and the soluble protein content was calculated according to the following formula:

[0045]

[0046] 2. Detection methods of particle size and potential

[0047] The particle size and ζ-potential of the hollow particles were detected using a NanoBrook Omni particle size analyzer.

[0048] 3. Microstructure detection method

[0049] The diluted sample was stained with 1% phosphotungstic acid, and the microscopic morphology of the particles was observed using a transmission electron microscope (TEM) at an electron acceleration voltage of 120 kV.

[0050] 4. Detection methods of particle hydrodynamic radius, root mean square radius of gyration and molecular weight

[0051] The hydrodynamic radius (Rh) of the sample at a scattering angle of 90° was measured by dynamic and static scattering. After the sample was diluted to a series of concentrations, it was measured by static light scattering at a scattering angle of 30-150°, and the root mean square gyration radius (Rg) and molecular weight of the sample were obtained by Zimm Plot fitting. The shape factor (ρ) was obtained by calculating the ratio of the root mean square gyration radius to the hydrodynamic radius.

[0052] 5. Protein molecular weight detection method

[0053] Sodium dodecyl sulfate-polyacrylamide electrophoresis (SDS-PAGE) was used to determine the molecular weight of proteins in hollow particles. The samples were boiled with sample buffer containing sodium dodecyl sulfate for 3 minutes, in which β-mercaptoethanol was added under reducing conditions, and then loaded onto polyacrylamide gel. The voltages of the stacking gel and separation gel were set to 80 V and 110 V, respectively. After separation, Coomassie Brilliant Blue R250 was used for staining.

[0054] 6. Shell hydrophobicity detection method:

[0055] A pyrene probe dissolved in acetone was added to the sample, and the fluorescence spectrum of the pyrene probe was scanned using a fluorescence spectrophotometer. The excitation wavelength was 335 nm, the emission spectrum scanning range was 350-600 nm, the excitation and emission slit widths were both 2.5 nm, and the intensity ratio of the first and third bands (I1 / I3) was calculated.

[0056] 7. Storage stability testing method:

[0057] The prepared zein-whey protein isolate composite hollow particles were stored at 25° C. and 45° C. for 28 days, and the particle size and ζ-potential of the hollow particles were detected using a NanoBrook Omni particle size analyzer every seven days.

[0058] 8. Detection methods for recovery rate, embedding rate and loading capacity:

[0059] The recovery rate, embedding rate and loading capacity of curcumin were determined by ultraviolet spectrophotometer, and the calculation formulas were:

[0060]

[0061]

[0062]

[0063] Example 1

[0064] A method for preparing zein-whey protein isolate composite hollow particles, the method comprising the following steps:

[0065] (1) dissolving zein powder in a 70% by volume ethanol solution to obtain an alcohol solution with a mass fraction of 10% zein;

[0066] (2) dissolving the whey protein isolate in a 70% by volume ethanol solution to obtain an alcohol solution having a mass fraction of 2.5% whey protein isolate;

[0067] (3) mixing the alcohol solution of 10% zein prepared in step (1) and the alcohol solution of 2.5% whey protein isolate prepared in step (2) in a volume ratio of 1:1, adjusting the pH to 11 with 2 mol / L NaOH, heating in a water bath at 85° C. for 30 min, and cooling to room temperature to obtain an alcohol solution of zein-whey protein isolate;

[0068] (4) adding sodium carbonate to a 70% by volume ethanol solution to obtain a sodium carbonate alcohol solution with a concentration of 10 mg / mL;

[0069] (5) mixing the sodium carbonate alcohol solution prepared in step (4) with the zein-whey protein isolate alcohol solution prepared in step (3) at a volume ratio of 1:1; transferring the mixture to the aqueous phase with ultrapure water at a volume ratio of 1:4, stirring at 1000 rpm for 10 min, and obtaining zein-whey protein isolate composite hollow particles having a pH of 11; and then adjusting the pH to 7 with 1 mol / L HCl to obtain neutral 0.5% zein-0.125% whey protein isolate composite hollow particles.

[0070] Example 2

[0071] A method for preparing zein-whey protein isolate composite hollow particles, the method comprising the following steps:

[0072] (1) dissolving zein powder in a 70% by volume ethanol solution to obtain an alcohol solution with a mass fraction of 10% zein;

[0073] (2) dissolving the whey protein isolate in a 70% by volume ethanol solution to obtain an alcohol solution with a mass fraction of 5% whey protein isolate;

[0074] (3) mixing the alcohol solution of 10% zein prepared in step (1) and the alcohol solution of 5% whey protein isolate prepared in step (2) in a volume ratio of 1:1, adjusting the pH to 11 with 2 mol / L NaOH, heating in a water bath at 85° C. for 30 min, and cooling to room temperature to obtain an alcohol solution of zein-whey protein isolate;

[0075] (4) adding sodium carbonate to a 70% by volume ethanol solution to obtain a sodium carbonate alcohol solution with a concentration of 10 mg / mL;

[0076] (5) mixing the sodium carbonate alcohol solution prepared in step (4) with the zein-whey protein isolate alcohol solution prepared in step (3) at a volume ratio of 1:1; transferring ultrapure water to the aqueous phase at a volume ratio of 1:4, stirring at 1000 rpm for 10 min, and obtaining zein-whey protein isolate composite hollow particles with a pH of 11; and then adjusting the pH to 7 with 1 mol / L HCl to obtain neutral 0.5% zein-0.25% whey protein isolate composite hollow particles.

[0077] Comparative Example 1

[0078] A method for preparing zein hollow particles, the method comprising the following steps:

[0079] The only difference from Example 1 is that: step (2) is omitted, the 2.5% alcohol solution of whey protein isolate in step (3) is replaced by a 70% ethanol solution without whey protein isolate, and other conditions remain unchanged; zein hollow particles with a pH of 11 are prepared; then, the pH is adjusted to 7 with 1 mol / L HCl to obtain neutral zein hollow particles.

[0080] Comparative Example 2

[0081] A method for preparing zein hollow particles (traditional method), the method comprising the following steps:

[0082] (1) adding sodium carbonate to a 70% by volume ethanol solution to obtain a sodium carbonate alcohol solution with a concentration of 10 mg / mL;

[0083] (2) The sodium carbonate alcohol solution prepared in step (1) is mixed with 5% zein dissolved in 70% ethanol solution in a volume ratio of 1:1, and then mixed with ultrapure water in a volume ratio of 1:4, and stirred at 1000 rpm for 10 minutes to obtain zein hollow particles prepared by a conventional method.

[0084] Performance measurement

[0085] 1. Determination of soluble protein content of the hollow protein particles prepared in Examples 1 to 2 and Comparative Examples 1 to 2

[0086] The results are as follows Figure 1 As shown, it can be found that compared with the zein hollow particles prepared by the conventional method in Comparative Example 2, the soluble protein content of the zein hollow particles prepared by alkali heat treatment in Comparative Example 1 (without whey protein) is increased to about 90%.

[0087] from Figure 1 It can be seen from the results that when whey protein isolate is not present or the concentration of whey protein isolate is low, the soluble protein content of the hollow particles under neutral pH conditions decreases significantly, and Figure 1 As can be seen in (A), precipitation is produced at the bottom without whey protein isolate or whey protein isolate. Since the isoelectric point of zein is around 6.2, when the whey protein isolate concentration is insufficient, the zein hollow particles are unstable under neutral conditions and are prone to aggregation. However, when the final concentration of whey protein isolate is increased to 0.25%, that is, when the mass ratio of zein to whey protein isolate is 1:0.5, the zein-whey protein isolate composite hollow particles are stable at pH 7, indicating that 0.25% whey protein isolate is sufficient to stabilize 0.5% zein hollow particles, at which time the soluble protein content is about 86%.

[0088] 2. Determine the particle size and ζ-potential of the zein hollow particles prepared by alkaline heat treatment in Comparative Example 1 and the zein-whey protein isolate composite hollow particles prepared in Examples 1-2.

[0089] The results are as follows Figure 2 As shown, from Figure 2 (A) and Figure 2 (B) It can be seen that the particle size of the zein hollow particles prepared by alkali heat treatment is unimodal distribution. With the increase of whey protein isolate content, the particle size and potential of the zein-whey protein isolate composite hollow particles increase. When the final concentration of whey protein isolate is 0.25%, the particle size of the zein-whey protein isolate composite hollow particles is about 90nm, and the ζ-potential is about -34mV. When the pH is adjusted to 7, the particle size of the composite hollow particles increases to 198nm, and the ζ-potential does not change significantly, which is about -32mV.

[0090] 3. Transmission electron microscopy observation of composite particle morphology

[0091] The zein-whey protein isolate composite hollow particles prepared in Example 2, wherein the final concentration of zein is 0.5% and the final concentration of whey protein isolate is 0.25%, were diluted 200 times with ultrapure water, stained with 1% phosphotungstic acid, and the microscopic morphology of the particles was observed using a transmission electron microscope (TEM) at an electron acceleration voltage of 120 kV.

[0092] The results are as follows Figure 3 shown; from Figure 3 (A) and 3(B), the TEM images of zein-whey protein isolate composite hollow particles under neutral conditions show a lighter core and a darker shell, indicating that the particles have a hollow structure.

[0093] 4. Characterization of the hollow structure of composite particles by dynamic and static light scattering

[0094] The zein-whey protein isolate composite hollow particles prepared under neutral conditions in Example 2, wherein the final concentration of zein is 0.5% and the final concentration of whey protein isolate is 0.25%, were used to measure the hydrodynamic radius (R) of the sample at a scattering angle of 90° using dynamic and static scattering. h After the sample was diluted to a series of concentrations, static light scattering was used for measurement at scattering angles of 30-150°, and the root mean square radius of gyration (R g ) and molecular weight. The shape factor (ρ) was calculated by calculating the ratio of the root mean square radius of gyration to the hydrodynamic radius.

[0095] Table 1 Structural parameters of zein-whey protein isolate composite hollow particles under neutral conditions

[0096]

[0097] As shown in Table 1, the ρ of the zein-whey protein isolate composite hollow particles at pH 7 is 1.01, which is very close to the ratio of the ideal hollow sphere 1.00, indicating that it has a hollow structure at pH 7. The molecular weight of the zein-whey protein isolate composite hollow particles is about 1.17×10 8 Da.

[0098] 5. Characterization of protein molecular weight in zein-whey protein isolate composite hollow particles

[0099] The results are as follows Figure 4 As shown in A, for zein, the two bands of 20 kDa and 25 kDa belong to α-zein, and the band above 30 kDa belongs to covalent aggregates, which are degraded after alkali-heat treatment. For whey protein isolate, the bands of 14, 16, 33 and 66 kDa belong to α-lactalbumin, β-lactoglobulin, β-lactoglobulin dimer and bovine serum albumin, respectively, and whey protein is aggregated after alkali-heat treatment.

[0100] For zein-whey protein isolate, the bands above 30 kDa, which are different from the individual proteins, indicate that covalent polymerization occurs between the two proteins. Figure 4 As shown in B, under reducing conditions, all bands became fainter but the monomer band was enhanced, indicating that disulfide bonds contribute to the aggregation of proteins in the shell.

[0101] 6. Shell hydrophobicity of zein-whey protein isolate composite hollow particles

[0102] The zein hollow particles prepared in Comparative Example 1 and the zein-whey protein isolate composite hollow particles prepared in Example 2 were used. When pyrene is transferred from a polar environment to a hydrophobic environment, the intensity ratio of the first and third bands (I1 / I3) in its fluorescence emission spectrum decreases, and pyrene is used as a fluorescent probe. Its fluorescence emission spectrum is measured by a fluorescence spectrophotometer, and the change in the intensity ratio of the first and third bands (I1 / I3) is calculated to explore the hydrophobicity of the shell; the I1 / I3 ratio of pyrene in water is 1.75.

[0103] The results are as follows Figure 5As shown in the figure, the I1 / I3 ratio in the zein hollow particles decreased to 1.14, indicating that the pyrene molecules were transferred from the aqueous phase to the hydrophobic shell of the hollow particles. At pH 11, the I1 / I3 ratio of pyrene in the zein-whey protein isolate composite hollow particles was greater than that in the zein hollow particles. When the pyrene concentration was 4 μM, the I1 / I3 value of the zein-whey protein isolate composite hollow particles gradually increased with the increase of whey protein isolate concentration. These results indicate that the shell of zein-whey protein isolate is less hydrophobic than the shell of zein alone. Whey protein isolate is water-soluble, while zein is alcohol-soluble.

[0104] It can be seen that the shell layer of the zein-whey protein isolate hollow particles is a mixed layer. At pH 7, the I1 / I3 ratio of pyrene in the zein-whey protein isolate composite hollow particles is greater than that at pH 11, indicating that under neutral conditions, the protein stacking of the shell layer is more compact.

[0105] 7. Storage stability of zein-whey protein isolate composite hollow particles

[0106] Example 2 Zein-whey protein isolate composite hollow particles were prepared at pH 7, wherein the final concentration of zein was 0.5% and the final concentration of whey protein isolate was 0.25%. The composite hollow particles were stored at 45° C. for 28 days, and the particle size and ζ-potential of the composite hollow particles were measured.

[0107] The results are as follows Figure 6 As shown: Figure 6 As shown in (A), when the pH is 7 and the storage temperature is 45°C, the particle size of the zein-whey protein isolate composite hollow particles does not change significantly after 21 days of storage, and shows a bimodal distribution after 28 days. Figure 6 As shown in (B), the ζ-potential of the zein-whey protein isolate composite hollow particles did not change significantly within 14 days, and then decreased with the extension of storage time. After storage at 45°C for 28 days, the ζ-potential decreased to about -27 mV.

[0108] The above results show that zein-whey protein isolate composite hollow particles have good storage stability.

[0109] Example 3

[0110] A method for preparing zein-whey protein isolate composite hollow particles embedded with curcumin, the method comprising the following steps:

[0111] (1) dissolving zein powder in a 70% by volume ethanol solution to obtain an alcohol solution with a mass fraction of 10% zein;

[0112] (2) dissolving the whey protein isolate in a 70% by volume ethanol solution to obtain an alcohol solution with a mass fraction of 5% whey protein isolate;

[0113] (3) mixing the alcohol solution of 10% zein prepared in step (1) and the alcohol solution of 5% whey protein isolate prepared in step (2) in a volume ratio of 1:1, adjusting the pH to 11 with 2 mol / L NaOH, heating in a water bath at 85° C. for 30 min, and cooling to room temperature to obtain an alcohol solution of zein-whey protein isolate;

[0114] (4) dissolving curcumin at concentrations of 0.5 and 1 mg / mL in the alcohol solution of zein-whey protein isolate prepared in step (3), respectively, and then mixing with a sodium carbonate alcohol solution at a volume ratio of 1:1, and then transferring to an aqueous phase at a volume ratio of 1:4, stirring at 1000 rpm for 10 min, to obtain zein-whey protein isolate composite hollow particles loaded with 0.05% curcumin and zein-whey protein isolate composite hollow particles loaded with 0.1% curcumin at a pH of 11, respectively;

[0115] Then, 1 mol / L HCl was used to adjust the pH to 7, and neutral zein-whey protein isolate composite hollow particles loaded with 0.05% curcumin and zein-whey protein isolate composite hollow particles loaded with 0.1% curcumin were obtained.

[0116] Performance measurement

[0117] The prepared curcumin-loaded zein-whey protein isolate composite hollow particle sample was centrifuged at 2000 rpm to remove the precipitated unencapsulated curcumin to obtain a curcumin-zein-whey protein isolate composite hollow particle solution, which was then centrifuged at 100,000 rpm and measured by ultraviolet spectrophotometer at λ max The curcumin content in the whole solution before centrifugation and the supernatant after centrifugation was determined at 426 nm, and the embedding rate, loading amount and recovery rate of curcumin were calculated.

[0118] The results are shown in Figure 2. The recovery rate was measured 1 hour after the preparation of the curcumin-loaded zein-whey protein isolate composite hollow particles. It was found that when the pH was 11, the initial addition concentration of curcumin was 0.5 and 1 mg / mL, and the recovery rates were 48% and 62%, respectively; if the pH of the zein-whey protein isolate composite hollow particles loaded with curcumin at pH 11 was immediately adjusted to pH 7 during preparation, the recovery rates were greater than 90%, indicating that the stability of curcumin can be maintained by adjusting the pH back to neutral after alkaline heat treatment, and thus the composite hollow particles can be used as potential embedding carriers for curcumin.

[0119] Table 2 Recovery of curcumin

[0120]

[0121]

[0122] The embedding efficiency and loading amount of curcumin were measured 2 hours after the preparation of the zein-whey protein isolate composite hollow particles loaded with curcumin. As shown in Tables 3 and 4, at pH 11, when the initial addition concentration of curcumin was 0.5 and 1 mg / mL, the embedding efficiency was 52% and 33%, respectively, and the loading amount was 1.84 and 3.01 g / 100 g, respectively; while at pH 7, the embedding efficiency was 88% and 81%, respectively, and the loading amount was 6.20 and 11.40 g / 100 g, respectively. When the mass ratio of zein to curcumin was 1:0.1 and 1:0.2, respectively, under neutral conditions, the embedding efficiency of curcumin was above 80%. Therefore, the zein-whey protein isolate composite hollow particles can be used for the embedding and loading of curcumin under neutral conditions.

[0123] Table 3 Encapsulation rate of curcumin

[0124]

[0125] Table 4 Curcumin loading

[0126]

[0127] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A prolamin-milk protein composite hollow particle, characterized in that: Prolamin and milk protein are covalently cross-linked to form a mixed shell of two proteins; the mass ratio of the prolamin to the milk protein is 10-15:2.5-5; the prolamin is zein; and the milk protein is whey protein isolate; The covalent cross-linking comprises the following steps: (1) mixing an alcohol solution of alcohol-soluble protein and an alcohol solution of milk protein, adjusting the pH to alkaline, heating at 70-95° C., and then cooling to room temperature to obtain an alcohol-soluble protein-milk protein composite alcohol solution; (2) mixing the alcohol solution of the sacrificial template with the alcohol solution of the alcohol ... (3) The pH of the alcohol-soluble protein-milk protein composite hollow particle solution obtained in step (2) is adjusted to 6-8 to obtain neutral alcohol-soluble protein-milk protein composite hollow particles.

2. The method for preparing the prolamin-milk protein composite hollow particles according to claim 1, characterized in that: The method comprises the following steps: (1) mixing an alcohol solution of alcohol-soluble protein and an alcohol solution of milk protein, adjusting the pH to alkaline, heating at 70-95° C., and then cooling to room temperature to obtain an alcohol-soluble protein-milk protein composite alcohol solution; (2) mixing the alcohol solution of the sacrificial template with the alcohol solution of the alcohol ... (3) The pH of the alcohol-soluble protein-milk protein composite hollow particle solution obtained in step (2) is adjusted to 6-8 to obtain neutral alcohol-soluble protein-milk protein composite hollow particles.

3. The method according to claim 2, characterized in that The mass ratio of the sacrificial template to the alcohol-soluble protein-milk protein in step (2) is 0.06:0.5-1.

5.

4. Use of the alcohol-soluble protein-milk protein composite hollow particles according to claim 1 or the preparation method of the alcohol-soluble protein-milk protein composite hollow particles according to any one of claims 2 to 3 in the preparation of food, health products or cosmetics.

5. The use according to claim 4, characterized in that: The application is to use the alcohol-soluble protein-milk protein composite hollow particles for embedding hydrophobic functional factors.

6. The use according to claim 5, characterized in that: The mass ratio of the hydrophobic functional factor to the alcohol-soluble protein is 0.1-0.2:

1.

7. The use according to claim 5 or 6, characterized in that: The hydrophobic functional factor includes one or more of curcumin, resveratrol, quercetin, α-tocopherol and retinol.

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