Pickering emulsion as well as preparation method and application thereof

Abstract

The invention relates to Pickering emulsion, a preparation method and application thereof, and belongs to the technical field of emulsion preparation, and the preparation method comprises the following steps: S1, preparing a water phase: uniformly mixing and stirring gluten protein zymolyte obtained after gluten protein enzymolysis with polydextrose and a phosphoric acid buffer solution, heating in a water bath, and cooling to obtain the water phase; s2, preparation of an oil phase: dissolving fat-soluble active substances in edible oil to prepare the oil phase; s3, emulsion preparation: mixing the water phase and the oil phase, performing high-speed dispersion treatment, and homogenizing to obtain Pickering emulsion; the gluten protein zymolyte and the polydextrose conjugate are prepared by utilizing the Maillard reaction, and the emulsibility and the stability of the Pickering emulsion can be remarkably improved by taking the gluten protein zymolyte and the polydextrose conjugate as the emulsifier.

Description

Technical Field

[0001] The invention belongs to the technical field of emulsion preparation, and specifically refers to a Pickering emulsion, a preparation method and application thereof. Background Art

[0002] Fat-soluble active substances include fat-soluble polyphenols, vitamins, polyunsaturated fatty acids, etc., which have biological activities such as anti-oxidation, anti-inflammatory, and regulating metabolic balance, but their poor water solubility limits their application in the food field. Constructing oil-in-water (O / W) Pickering emulsions to encapsulate these fat-soluble active substances and greatly improve their bioavailability is an effective way to solve this problem.

[0003] Oil-in-water (O / W) Pickering emulsions are widely used and have the advantages of good stability and strong resistance to adverse environments, making them suitable as liquid beverage additives. In addition, Pickering emulsions, as a delivery system commonly used for delivering drugs and active ingredients, have broad application prospects in functional foods and other fields.

[0004] In the context of sustainable development, fully exploring the utilization value of wheat-derived protein has become a future development trend. The Pickering emulsion delivery system is a research hotspot for improving the bioavailability of functional active substances. Gluten protein is widely available and has good hydrophobicity. It is a potential Pickering emulsion emulsifier. However, the hydrophilicity of single gluten protein is poor, and the prepared Pickering emulsion has insufficient emulsifying activity and stability. Summary of the invention

[0005] In order to overcome some of the problems mentioned in the above background, the present invention provides a method for preparing a Pickering emulsion.

[0006] According to the technical solution of the present invention, a method for preparing a Pickering emulsion is provided, comprising the following steps:

[0007] S1 preparation of aqueous phase: mixing the gluten protease hydrolysate obtained after gluten protease hydrolysis with polydextrose and phosphate buffer solution, stirring evenly, heating in a water bath, and then cooling to obtain an aqueous phase;

[0008] S2 Preparation of oil phase: dissolving the fat-soluble active substance in edible oil to prepare an oil phase;

[0009] Preparation of S3 emulsion: The water phase and the oil phase are mixed and then dispersed at a high speed, and then homogenized to obtain a Pickering emulsion.

[0010] Furthermore, the preparation method of the gluten protein hydrolysate is:

[0011] Dissolve gluten protein in water, add a pH regulator to adjust the solution pH to 9, add alkaline protease and continue stirring under high temperature conditions for enzymolysis. After the enzymolysis is completed, heat it in boiling water to inactivate the alkaline protease, cool it to room temperature, centrifuge it, collect the hydrolyzate, and freeze-dry it to obtain the gluten enzymatic hydrolysate.

[0012] Furthermore, the gluten protein is enzymatically hydrolyzed under high temperature conditions for 1-6 hours;

[0013] The degree of enzymatic hydrolysis of the gluten protein after enzymatic hydrolysis is 3.20%-10.13%.

[0014] Further, the gluten protein hydrolysate and polydextrose are mixed and dissolved in a 0.05 mol / L phosphate buffer solution with a pH value of 7 at a mass ratio of 1:(2-3) to obtain a preheated mixed solution.

[0015] Furthermore, the preheated mixed solution was reacted in a water bath at 90° C. for 4 hours to obtain a Maillard product, and the degree of grafting of the gluten protein hydrolysate with polydextrose was 83.31%-87.29%.

[0016] Furthermore, the mass concentration of the fat-soluble active substance in the oil phase is 2-12 mg / mL, the edible oil is soybean oil, and the fat-soluble active substance is curcumin.

[0017] Furthermore, the step S1 also includes adjusting the pH of the aqueous phase to 8.

[0018] Furthermore, the specific steps of S3 are:

[0019] The water phase and the oil phase were mixed in a volume ratio of 3:97 and then subjected to high-speed dispersion treatment at 12000 r / min for 1-4 min, followed by homogenization at 40 MPa for 5 times to obtain a Pickering emulsion.

[0020] The present invention further provides a Pickering emulsion: the Pickering emulsion prepared by the above method.

[0021] Furthermore, the present invention also provides an application of the Pickering emulsion, wherein the Pickering emulsion is applied in the food field.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] The present invention covalently combines gluten protein hydrolysate and polydextrose through the Maillard reaction, and uses the emulsifier to prepare Pickering emulsion, which can improve the emulsification activity and stability of the Pickering emulsion, and the protein is more easily adsorbed on the interface, which can better improve the stability of the Pickering emulsion system and realize the delivery of active ingredients. The gluten protein hydrolysate and the Maillard reaction product of polydextrose are used as carriers to improve the stability of the Pickering emulsion and the embedding rate of fat-soluble active substances. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a diagram showing the degree of enzymatic hydrolysis of gluten protein hydrolysates prepared in Examples 1-6 of the present invention;

[0025] Figure 2 is a graph showing the grafting degree of the gluten protein hydrolysate and the polyglucose Maillard reaction product of the present invention;

[0026] Figure 3 It is a microstructure determination diagram of the gluten protein hydrolysate and the polyglucose Maillard reaction product of the present invention;

[0027] Figure 4 It is a solubility determination diagram of the gluten protein hydrolysate and the polyglucose Maillard reaction product of the present invention;

[0028] Figure 5 The emulsifying activity and emulsifying stability of the gluten protease hydrolysate and the polyglucose Maillard reaction product of the present invention;

[0029] Figure 6 It is a graph showing the average particle size and Zeta potential of the Pickering emulsion using gluten protein hydrolysate and polyglucose Maillard reaction product as carriers;

[0030] Figure 7 It is a microscopic morphological determination diagram of the Pickering emulsion of the present invention using gluten protein hydrolysate and polyglucose Maillard reaction product as carriers;

[0031] Figure 8 The figure is a graph showing the average particle size and Zeta potential of a Pickering emulsion containing a gluten protease hydrolysate and a polyglucose Maillard reaction product as a carrier at different salt ion concentrations;

[0032] Fig. 9 The figure is a graph showing the average particle size and Zeta potential of a Pickering emulsion containing a gluten protein hydrolysate and a polyglucose Maillard reaction product as a carrier at different pH values;

[0033] Fig.10 The figure is a graph showing the average particle size and Zeta potential of a Pickering emulsion containing a gluten protease hydrolysate and a polyglucose Maillard reaction product as a carrier at different temperatures;

[0034] Fig.11 This is a graph showing the encapsulation efficiency of curcumin by the Pickering emulsion prepared in Examples 7-12 of the present invention;

[0035] Fig.12 is a graph showing the average particle size and Zeta potential of the Pickering emulsions prepared in Examples 7-12 of the present invention;

[0036] Fig.13 is the POV value of the Pickering emulsion prepared in Examples 7-12 stored at 4°C for 14 days;

[0037] Fig.14 is the TBARS value of the Pickering emulsions prepared in Examples 7-12 stored at 4°C for 14 days. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection.

[0039] Under the background of sustainable development, fully exploring the utilization value of wheat-derived protein has become a future development trend, and the Pickering emulsion delivery system is a research hotspot for improving the bioavailability of functional active substances. The gluten protein selected in the present invention has a wide range of sources and good hydrophobicity, and is a potential Pickering emulsion emulsifier, but the hydrophilicity of single gluten protein is poor. Polydextrose has the functional properties of good hydrophilicity and dispersion stability. Gluten protein hydrolysate and polydextrose conjugate are prepared by Maillard reaction, and using them as emulsifiers can significantly improve the emulsification and stability of Pickering emulsion. The construction of Pickering emulsion using gluten protein hydrolysate and polydextrose Maillard reaction products has good application prospects. It can be applied to functional food and other fields.

[0040] Required test methods:

[0041] Determination of gluten enzymatic hydrolysis degree: 1 mL of enzymatic hydrolysis solution, 1 mL of phosphate buffer, and 1 mL of ninhydrin solution (0.02 g / mL) are added to a 25 mL test tube, boiled in water for 15 minutes, cooled to room temperature, fixed to 25 mL, and the absorbance at a wavelength of 570 nm is measured. Glycine is used as the standard curve. The degree of hydrolysis is calculated according to the formula: DH (%) = (Ni-N0) / N*100%, where Ni is the nitrogen content after enzymatic hydrolysis; N0 is the nitrogen content without enzymatic hydrolysis; and N is the total nitrogen content of the sample.

[0042] Preparation of gluten protein hydrolysate-polydextrose Maillard reaction product: Gluten protein hydrolysate with different enzymatic hydrolysis time (1, 2, 3, 4, 5, 6 h) and polydextrose were dissolved in 100 mL of 0.05 mol / L phosphate buffer solution (pH 7.0) at a ratio of 1:2.2 (w / w), stirred for 30 min to completely dissolve, the mixed sample was heated in a 90°C water bath for 4 h, the reaction was terminated in an ice bath, and the prepared reaction product aqueous solution was freeze-dried.

[0043] Determination of grafting degree: Using SDS solution with a mass concentration of 1 mg / mL as solvent, prepare a solution of the reaction product with a mass concentration of 2 mg / mL, take 0.4 mL and mix it with 2 mL phosphate buffer of pH 8.2, add 1 mL of 0.1 mg / mL TNBS reagent and mix evenly, bathe in a light-proof water bath at 50°C for 30 min, add 2 mL of 0.1 mol / L Na2SO3 solution to terminate the reaction, let it stand at room temperature for 30 min, measure the absorbance at a wavelength of 420 nm, and calculate the grafting degree (%) according to the formula: (A0-Ai) / A0×100%, where 0 represents the absorbance of the sample when it is not reacted; Ai represents the absorbance of the sample after the reaction has lasted for i time.

[0044] Microstructure determination of Maillard reaction products: The freeze-dried Maillard reaction products were sprayed with gold on the surface of the conductive adhesive under vacuum conditions and scanned using a scanning electron microscope.

[0045] Solubility determination: Weigh 0.10 g of sample and mix with water, adjust pH to 7, dilute to 10 mL, vortex for 3 min to fully dissolve, centrifuge at 4000 r / min for 10 min. Measure the absorbance at 540 nm, using bovine serum albumin as the standard curve.

[0046] Emulsification property determination: 24 mL of 2 mg / mL freeze-dried Maillard reaction product was dissolved in 0.2 mol / L pH 8.2 phosphate buffer and mixed with soybean oil in a ratio of 97:3. 50 μL of sample was taken at 0 min and 10 min, and 5 mL In 0.1% SDS solution, the absorbance value (A0, A10) at a wavelength of 500nm was measured, and the SDS solution was used as a blank control. The formulas are as follows (3) and (4): Emulsification activity index EAI (m2 / g) = (2*2.303*A0*DF) / (C**(1-θ))*1000; Emulsification stability ESI (min) = A0 / (A0-A10)*10, where DF is the dilution factor, DF=100, C is the sample mass concentration (g / mL); φ is the optical path, φ=1cm; θ is the proportion of the oil phase in the emulsion, θ=0.25; A0 is the absorbance value measured at 0min; A10 is the absorbance value measured at 10min.

[0047] Determination of average particle size and Zeta potential of emulsion: The average particle size and Zeta potential of the sample were measured using a nanoparticle size potentiometer. The detection temperature was 25°C, the thermal equilibrium time was 120s, the refractive index of the dispersant / water was 1.330, and the refractive index of the particles was 1.540.

[0048] Microstructure determination of emulsion: The morphology of Pickering emulsion prepared by gluten protease hydrolysate and polyglucose Maillard reaction product was observed using confocal laser scanning microscopy. 1g of Nile blue and 100mL of distilled water were evenly mixed. 10μL of Nile blue solution was added to 1mL of sample, stained and allowed to stand for 15min in the dark, and then dropped onto a glass slide and covered with a coverslip. The excitation wavelength was 633nm, and the microstructure of Pickering emulsion was observed.

[0049] Determination of ionic strength stability of emulsion: Prepare 50, 100, 150, 200 and 250 mmol / L NaCl solutions. Mix 3 mL of Pickering emulsion with 3 mL of NaCl solutions of different concentrations. Let stand at room temperature for 24 h, and observe the changes in the average particle size and Zeta potential of the Pickering emulsion.

[0050] pH stability of emulsion: The pH of the Pickering emulsion was adjusted to 3.0, 5.0, 7.0, and 9.0, respectively. The emulsion was allowed to stand at room temperature for 24 hours, and the changes in the average particle size and Zeta potential of the Pickering emulsion were observed.

[0051] Thermal stability of the emulsion: The Pickering emulsion was heated in a water bath at 50°C, 70°C, and 90°C for 20 min. After being placed at room temperature for 24 h, the changes in the average particle size and Zeta potential of the Pickering emulsion were observed.

[0052] Determination of curcumin encapsulation efficiency: 1 mL of Pickering emulsion was mixed with 2 mL of 95% ethanol, centrifuged at 2000 rpm for 10 min, and the absorbance of free curcumin content of Pickering emulsion was measured at a wavelength of 425 nm. The formula for the encapsulation efficiency of curcumin encapsulated in Pickering emulsion is: (W1-W2) / W1*100%, where W1 represents the total content of curcumin in the Pickering emulsion sample, and W2 represents the content of free curcumin in the aqueous phase.

[0053] Determination of POV: Pickering emulsion was embedded with different amounts of curcumin at room temperature for 0, 3, 7, and 14 days. The content of hydrogen peroxide in Pickering emulsion was determined by ultraviolet spectrophotometry. 0.3 mL of Pickering emulsion was added to 1.5 mL of isooctane / propylamine (3:1, v / v), mixed evenly, and centrifuged at 5000 r / min for 15 min. 200 μL of the upper oil phase was added to 2.8 mL of methanol / 1-butanol solution (2:1, v / v), and then 15 μL of ammonium ferric thiocyanate and ferrous solution (0.132 mol / LBaCl2 and 0.144 mol / LFeSO4) were added respectively. The mixed solution was kept away from light for 20 minutes, and the absorbance at 510 nm was measured. Hydrogen peroxide was used as a standard curve. The POV value of Pickering emulsion was determined.

[0054] Determination of TBARS: 1 mL of Pickering emulsion and 2 mL of thiobarbituric acid solution (configuration: 15 g of trichloroacetic acid, 375 mg of thiobarbituric acid, and 12 mol / L hydrochloric acid mixed in 82.9 mL of water) were vortexed for 2 min, mixed evenly, boiled in boiling water for 15 min, cooled to room temperature, filtered through a 0.45 μm microporous filter membrane, and the absorbance at 532 nm was measured.

[0055] The present invention provides a method for preparing a Pickering emulsion, comprising the following steps:

[0056] S1 preparation of aqueous phase: mixing the gluten protease hydrolysate obtained by gluten protease hydrolysis with polydextrose and phosphate buffer solution, stirring evenly, heating in a water bath, and then cooling to obtain an aqueous phase;

[0057] S2 Preparation of oil phase: dissolving the fat-soluble active substance in edible oil to prepare an oil phase;

[0058] Preparation of S3 emulsion: The water phase and the oil phase are mixed and then dispersed at a high speed, and then homogenized to obtain a Pickering emulsion.

[0059] It should be noted that gluten protein is a byproduct of starch extraction from wheat flour. Compared with proteins from soybeans, peas or animals, gluten protein is cheaper, but contains a large amount of non-polar amino acids and is insoluble in water at neutral pH. Therefore, enzymatic hydrolysis of gluten protein unfolds its molecular structure, exposing hydrophobic groups to form amphiphilic polypeptide chains. This significantly enhances its interfacial adsorption capacity, making it easier to adsorb on the oil-water interface, reducing interfacial tension, and thus improving emulsification activity.

[0060] The gluten protein hydrolysate and polydextrose are covalently bonded through the Maillard reaction and used as an emulsifier to prepare Pickering emulsion, which can improve the emulsification activity and stability of Pickering emulsion. Proteins are more easily adsorbed on the interface, which can better improve the stability of the Pickering emulsion system and achieve the delivery of active ingredients. The use of gluten protein hydrolysate and polydextrose Maillard reaction products as carriers can improve the stability of Pickering emulsion and the embedding rate of fat-soluble active substances to a certain extent.

[0061] In a further embodiment of this embodiment, the preparation method of the gluten protein hydrolysate is:

[0062] Dissolve gluten protein in water, add a pH regulator to adjust the solution pH to 9, add alkaline protease and continue stirring under high temperature conditions for enzymolysis. After the enzymolysis is completed, heat it in boiling water to inactivate the alkaline protease, cool it to room temperature, centrifuge it, collect the hydrolyzate, and freeze-dry it to obtain the gluten enzymatic hydrolysate.

[0063] It should be noted that the specific enzymatic hydrolysis method of gluten protein is as follows: the protein solution (10%, w / w) is prepared by dissolving wheat gluten protein (10 g) in deionized water (100 mL); then a NaOH solution with a concentration of 0.1 mol / L is added to adjust the pH to 9, and then alkaline protease is added, and the enzyme-substrate ratio is 0.2% (w / w); the solution is hydrolyzed under continuous stirring at 50°C. After the hydrolysis is completed, the solution is heated in boiling water for 15 minutes to inactivate the enzyme, and cooled to room temperature to terminate the enzymatic hydrolysis. The hydrolyzate is centrifuged at 5000 r / min for 30 minutes, and the hydrolyzate is collected and freeze-dried for standby use.

[0064] In a further embodiment of this example, the gluten protein is enzymatically hydrolyzed under high temperature conditions for 1-6 hours;

[0065] The degree of enzymatic hydrolysis of the gluten protein after enzymatic hydrolysis is 3.20%-10.13%.

[0066] In a further implementation of this example, gluten protein hydrolysate and polydextrose are mixed and dissolved in a 0.05 mol / L phosphate buffer solution with a pH value of 7 at a mass ratio of 1:(2-3) to obtain a preheated mixed solution.

[0067] In a further embodiment of this example, the preheated mixed solution is reacted in a water bath at 90° C. for 4 hours to obtain a Maillard product, and the degree of grafting of the gluten protein hydrolysate with polydextrose is 83.31%-87.29%.

[0068] It should be noted that: the Maillard reaction of gluten protease hydrolysate and polydextrose (high molecular weight polysaccharide) forms a conjugate complex. The reaction is a product with the following characteristics through the condensation of amino groups and reducing sugars at high temperature:

[0069] Enhanced steric hindrance: The long-chain structure of polydextrose forms a thick interfacial layer on the surface of oil droplets, inhibiting droplet aggregation through physical barrier effect; Electrostatic repulsion regulation: Optimization of the charge density of the complex (such as through pH regulation) can enhance the electrostatic repulsion between droplets and further stabilize the emulsion; Improved antioxidant properties: The reducing groups in the Maillard reaction products (such as hydroxyl groups and furans) give the emulsion antioxidant ability, delay lipid oxidation, and are suitable for active ingredient delivery systems.

[0070] Moderate reaction can optimize the grafting effect, avoiding excessive reaction time that leads to the formation of large molecular polymers and reduces solubility, and too short reaction time that leads to insufficient grafting.

[0071] In a further embodiment of this example, the mass concentration of the fat-soluble active substance in the oil phase is 2-12 mg / mL, the edible oil is soybean oil, and the fat-soluble active substance is curcumin.

[0072] In a further embodiment of this example, the step S1 further includes adjusting the pH of the aqueous phase to 8.

[0073] In a further implementation of this embodiment, the specific steps of S3 are:

[0074] The water phase and the oil phase were mixed in a volume ratio of 3:97 and then subjected to high-speed dispersion treatment at 12000 r / min for 1-4 min, followed by homogenization at 40 MPa for 5 times to obtain a Pickering emulsion.

[0075] Example 1

[0076] The protein solution (10%, w / w) was prepared by dissolving wheat gluten protein (10 g) in deionized water (100 mL), and then a 0.1 mol / L NaOH solution was added to adjust the pH to 9, and then alkaline protease was added, and the enzyme-substrate ratio was 0.2% (w / w); the solution was hydrolyzed at 50°C for 1 hour with constant stirring. After the hydrolysis was completed, the solution was heated in boiling water for 15 minutes to inactivate the enzyme, and cooled to room temperature to terminate the enzymatic hydrolysis. The hydrolyzate was centrifuged at 5000 r / min for 30 minutes, and the hydrolyzate was collected and freeze-dried to obtain a gluten protease hydrolyzate with an enzymatic degree of 3.20% for standby use.

[0077] Preparation of the aqueous phase: The gluten protein hydrolysate and polydextrose prepared above are mixed and dissolved in water at a mass ratio of 1:2.2 to carry out a Maillard reaction, and the product after the reaction is prepared into a suspension with a mass concentration of 1%; the pH is adjusted to 8 with a phosphate buffer solution, and then the Maillard reaction is carried out in a water bath at 90° C. for 4 hours to prepare an aqueous phase; wherein the degree of grafting of gluten protein and polydextrose is 83.31%.

[0078] Preparation of oil phase: Edible oil-soybean oil is used as the oil phase.

[0079] Preparation of emulsion: The oil phase prepared in step S2 was mixed with the water phase prepared in step S1 at a volume ratio of 3:97, and the mixture was dispersed at 12000 r / min for 2 min. Homogenized at 40 MPa for 5 times to obtain a Pickering emulsion.

[0080] Example 2

[0081] The difference between this embodiment and embodiment 1 is that:

[0082] The hydrolysis time of wheat gluten protein is 2 hours, and the degree of enzymatic hydrolysis of the obtained gluten protein hydrolysate is 6.75%; the degree of grafting of gluten protein and polydextrose in the prepared aqueous phase is 84.24%.

[0083] Example 3

[0084] The difference between this embodiment and embodiment 1 is that:

[0085] The hydrolysis time of wheat gluten protein is 3 hours, and the degree of enzymatic hydrolysis of the obtained gluten protein hydrolysate is 8.23%; the degree of grafting of gluten protein and polydextrose in the prepared aqueous phase is 85.31%.

[0086] Example 4

[0087] The difference between this embodiment and embodiment 1 is that:

[0088] The hydrolysis time of wheat gluten protein is 4 hours, and the degree of enzymatic hydrolysis of the obtained gluten protein hydrolysate is 8.97%; the degree of grafting of gluten protein and polydextrose in the prepared aqueous phase is 86.49%.

[0089] Example 5

[0090] The difference between this embodiment and embodiment 1 is that:

[0091] The hydrolysis time of wheat gluten protein is 5 hours, and the degree of enzymatic hydrolysis of the obtained gluten protein hydrolysate is 9.55%; the degree of grafting of gluten protein and polydextrose in the prepared aqueous phase is 86.98%.

[0092] Example 6

[0093] The difference between this embodiment and embodiment 1 is that:

[0094] The hydrolysis time of wheat gluten protein is 6 hours, and the degree of enzymatic hydrolysis of the obtained gluten protein hydrolysate is 10.13%; the degree of grafting of gluten protein and polydextrose in the prepared aqueous phase is 87.30%.

[0095] Example 7

[0096] The difference between this embodiment and embodiment 4 is that:

[0097] Preparation of oil phase: Curcumin was dissolved in edible oil to prepare a curcumin-soybean oil solution with a mass concentration of 2 mg / mL.

[0098] Example 8

[0099] The difference between this embodiment and embodiment 4 is that:

[0100] Preparation of oil phase: Curcumin was dissolved in edible oil to prepare a curcumin-soybean oil solution with a mass concentration of 4 mg / mL.

[0101] Example 9

[0102] The difference between this embodiment and embodiment 4 is that:

[0103] Preparation of oil phase: Curcumin was dissolved in edible oil to prepare a curcumin-soybean oil solution with a mass concentration of 6 mg / mL.

[0104] Example 10

[0105] The difference between this embodiment and embodiment 4 is that:

[0106] Preparation of oil phase: Dissolve curcumin in edible oil to prepare a curcumin-soybean oil solution with a mass concentration of 8 mg / mL.

[0107] Embodiment 11

[0108] The difference between this embodiment and embodiment 4 is that:

[0109] Preparation of oil phase: Dissolve curcumin in edible oil to prepare a curcumin-soybean oil solution with a mass concentration of 10 mg / mL.

[0110] Example 12

[0111] The difference between this embodiment and embodiment 4 is that:

[0112] Preparation of oil phase: Dissolve curcumin in edible oil to prepare a curcumin-soybean oil solution with a mass concentration of 12 mg / mL.

[0113] Comparative Example

[0114] The difference from Example 1 is that the gluten protein is not enzymatically hydrolyzed, but the gluten protein and polydextrose are directly subjected to the Maillard reaction, and the reaction product is prepared into a suspension with a mass concentration of 1%; wherein the grafting degree of gluten protein and polydextrose is 19.68%.

[0115] The above test method was used to test Examples 1-12 and the comparative example. The results are as follows: Figure 1-Figure 14 shown.

[0116] like Figure 1-7 The enzymatic hydrolysis time of gluten protein is 0-6 hours. The increase of time improves the grafting degree, solubility, emulsification activity and stability of the Maillard reaction product of gluten protein hydrolysate and polyglucose. Figure 3 and Figure 4 A in the figure corresponds to the result of gluten protein hydrolysis time of 0h, i.e. no enzymatic hydrolysis of gluten protein. Figure 3 and Figure 4 B / C / D / E / F / G correspond to the test results of gluten protein hydrolysis time of 1, 2, 3, 4, 5 and 6 hours respectively.

[0117] like Figure 2 The results show that the grafting degree of gluten protein and polyglucose Maillard reaction products at different enzymatic hydrolysis times was analyzed. The grafting degree of gluten protein and polyglucose Maillard reaction products was the highest (86.49%) at 4h of enzymatic hydrolysis, and further extending the enzymatic hydrolysis time did not increase the grafting degree of the two.

[0118] like Figure 4-7 The emulsification characteristics of the Maillard reaction products of different enzymatic hydrolysis times were analyzed by emulsification characteristics. The solubility and emulsification activity of the enzymatic hydrolysates and polyglucose Maillard reaction products of 4, 5, and 6 hours of enzymatic hydrolysis were strong, thereby reducing the oil droplet size of the Pickering emulsion and improving the stability of the water-in-oil Pickering emulsion.

[0119] like Figure 8-Figure 10 The Pickering emulsion particles of the gluten protease hydrolysate and polyglucose Maillard reaction product are smaller at pH 8, no salt ions and 30-70°C, and the system is more stable. Under the condition of 30-70°C, the particle size of the Pickering emulsion is smaller and the stability is higher. Figure 8 As shown in the figure, the particle size and Zeta potential of Pickering emulsion with gluten protease hydrolysate and polyglucose Maillard reaction product (1:2.2) as carriers were measured under the conditions of 0-250mmol / L salt ions, pH 3-pH 9, and 30-90℃. The results show that the more salt ions there are, the larger the particle size of the Pickering emulsion and the smaller the absolute value of the Zeta potential. Fig. 9 As shown in the figure, the particle size of Pickering emulsion is smaller at pH 8 and pH 9. Fig.10 As shown in the figure, under the condition of 30-70°C, the particle size of Pickering emulsion is smaller and the stability is higher.

[0120] like Fig.11The figure shows the analysis of the encapsulation efficiency of Pickering emulsion for curcumin and the POV and TBARS values ​​of the emulsion after storage for 14 days. The results showed that there was no significant difference in the encapsulation efficiency of curcumin in Pickering emulsion when 8 mg / mL and 10 mg / mL curcumin were added, which were 80.58% and 79.67%, respectively; the POV values ​​of the emulsion after storage for 14 days were 0.86±0.01 mg / mL and 0.84±0.01 mg / mL, respectively, which were significantly lower (P<0.05) than the emulsion without curcumin (1.37±0.05 mg / mL); the TBARS values ​​of the emulsion after storage for 14 days were 0.17±0.003 mg / mL and 0.18±0.003 mg / mL, respectively, which were significantly lower (P<0.05) than the emulsion without curcumin (0.25±0.01 mg / mL); this indicates that the emulsion containing 8 mg / mL and 10 mg / mL curcumin has good storage stability and higher active substance (curcumin) protection ability.

[0121] like Fig.12 The results show that the Pickering emulsions containing 10 and 12 mg / mL curcumin have the largest average particle size and Zeta potential, indicating that curcumin greater than or equal to 10 mg / mL will reduce the stability of the Pickering emulsion.

[0122] like Fig.13 and Fig.14 The peroxide value (POV) and thiobarbituric acid (TBARS) values ​​of Pickering emulsions containing gluten protease hydrolysate and polydextrose Maillard reaction products as carriers stored at 4°C for 14 days are shown in the figure. The Pickering emulsion containing 8 mg / mL curcumin has the lowest POV and TBARS during the storage period, indicating that when 8 mg / mL curcumin is added, the Pickering emulsion containing gluten protease hydrolysate and polydextrose Maillard reaction products as carriers has good storage stability and high active substance protection ability.

[0123] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a Pickering emulsion, characterized in that: The following steps are involved: S1 preparation of aqueous phase: mixing the gluten protease hydrolysate obtained after gluten protease hydrolysis with polydextrose and phosphate buffer solution, stirring evenly, heating in a water bath, and then cooling to obtain an aqueous phase; S2 Preparation of oil phase: dissolving the fat-soluble active substance in edible oil to prepare an oil phase; Preparation of S3 emulsion: The water phase and the oil phase are mixed and then dispersed at a high speed, and then homogenized to obtain a Pickering emulsion.

2. The method for preparing the Pickering emulsion according to claim 1, characterized in that: The preparation method of the gluten protein hydrolysate is: Dissolve gluten protein in water, add a pH regulator to adjust the solution pH to 9, add alkaline protease and continue stirring under high temperature conditions for enzymolysis. After the enzymolysis is completed, heat it in boiling water to inactivate the alkaline protease, cool it to room temperature, centrifuge it, collect the hydrolyzate, and freeze-dry it to obtain the gluten enzymatic hydrolysate.

3. The method for preparing the Pickering emulsion according to claim 2, characterized in that: The gluten protein is enzymatically hydrolyzed under high temperature conditions for 1-6 hours; The degree of enzymatic hydrolysis of the gluten protein after enzymatic hydrolysis is 3.20%-10.13%.

4. The method for preparing the Pickering emulsion according to claim 1, characterized in that: The gluten protein hydrolysate and polydextrose are mixed and dissolved in a 0.05 mol / L phosphate buffer solution with a pH value of 7 at a mass ratio of 1:(2-3) to obtain a preheated mixed solution.

5. The method for preparing the Pickering emulsion according to claim 3, characterized in that: The preheated mixed solution is reacted in a water bath at 90° C. for 4 hours to obtain a Maillard product, and the grafting degree of the gluten protein hydrolysate and polydextrose is 83.31%-87.29%.

6. The method for preparing the Pickering emulsion according to claim 1, characterized in that: The mass concentration of the fat-soluble active substance in the oil phase is 2-12 mg / mL, the edible oil is soybean oil, and the fat-soluble active substance is curcumin.

7. The method for preparing the Pickering emulsion according to claim 1, characterized in that: The step S1 further includes adjusting the pH of the aqueous phase to 8.

8. The method for preparing the Pickering emulsion according to claim 1, characterized in that: The specific steps of S3 are: The water phase and the oil phase were mixed in a volume ratio of 3:97 and then subjected to high-speed dispersion treatment at 12000 r / min for 1-4 min, followed by homogenization at 40 MPa for 5 times to obtain a Pickering emulsion.

9. A Pickering emulsion, characterized in that: A Pickering emulsion prepared according to any one of claims 1 to 8.

10. An application of Pickering emulsion, characterized in that: The Pickering emulsion prepared according to any one of claims 1 to 8 is used in the food field.

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