Dual Pickering emulsion, preparation method and application thereof, and preparation method of probiotic protein bar

Abstract

The invention relates to the technical field of emulsion embedding, in particular to a dual Pickering emulsion, a preparation method and application thereof and a preparation method of a probiotic protein bar. The invention provides a preparation method of a dual Pickering emulsion, which comprises the following steps: adding a dispersion liquid of probiotics into an oil phase solution, and carrying out water-in-oil treatment to obtain a first emulsion; mixing the walnut protein soft nanoparticle emulsion and the walnut protein nanofiber emulsion to obtain a water phase solution; and putting the first emulsion into the aqueous phase solution, and carrying out oil-in-water treatment to obtain the dual Pickering emulsion. The dual Pickering emulsion has excellent thermal stability and mechanical properties and a relatively high probiotic loading rate.

Description

Technical Field

[0001] The invention relates to the technical field of emulsion embedding, and in particular to a double Pickering emulsion and a preparation method and application thereof, and a preparation method of a probiotic protein bar. Background Art

[0002] Probiotics are a type of living microorganisms that are beneficial to human health. They are mainly colonized in the human intestine and reproductive system, and can produce definite health effects, improve the host's microecological balance, and promote the improvement of body functions. The efficacy of probiotics has been widely recognized by the public in recent years. Protein bars are a kind of nutritious food with high protein content (generally greater than 20%), portable, and easy to give it functionality. They are generally produced using cold processing technology and are ready to eat after opening the bag. The cold processing process generally adopts the method of first boiling the liquid and then mixing it with solid auxiliary materials. When making pastries, syrup mixed with some oil is generally used as the liquid part, and the boiling temperature is between 100 and 110°C. The ordinary probiotic addition technology, due to the high temperature of the addition environment, the probiotic bacteria lack protection, which will cause a large number of bacteria to die due to heat, and cannot play a role when eaten, and loses the meaning of its addition. Due to this, there are few protein bar products with added probiotics on the market. Summary of the invention

[0003] In view of this, the object of the present invention is to provide a double Pickering emulsion and a preparation method and application thereof, and a preparation method of a probiotic protein bar. The double Pickering emulsion has excellent thermal stability, mechanical properties and a high probiotic loading rate.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The present invention provides a method for preparing a double Pickering emulsion, comprising the following steps:

[0006] Adding the dispersion of probiotics into the oil phase solution to perform water-in-oil process to obtain a first emulsion;

[0007] mixing walnut protein soft nanoparticle emulsion and walnut protein nanofiber emulsion to obtain an aqueous phase solution;

[0008] The first emulsion is placed in the aqueous phase solution to perform water-in-oil reaction to obtain a double Pickering emulsion.

[0009] Preferably, the ratio of probiotics to water in the probiotic dispersion is (0.5-1) g: 12 mL;

[0010] The oil phase solution includes a surfactant and a vegetable oil;

[0011] The volume ratio of the surfactant to the vegetable oil is (1-2):(48-50).

[0012] Preferably, the volume ratio of the probiotic dispersion to the oil phase solution is (0.8-1.2):(3.5-4.5);

[0013] The water-in-oil reaction is carried out under shearing conditions, the shearing speed is 5000-5500 rpm, and the time is 4-10 minutes.

[0014] Preferably, the volume ratio of the walnut protein soft nanoparticle emulsion and the walnut protein nanofiber emulsion is (0-10): (10-0), and the volumes of the peach protein soft nanoparticle emulsion and the walnut protein nanofiber emulsion are not 0;

[0015] The mass percentage concentration of walnut protein soft nanoparticles in the walnut protein soft nanoparticle emulsion is 70-90%;

[0016] The mass percentage concentration of the walnut protein nanofibers in the walnut protein nanofiber emulsion is 50-70%.

[0017] Preferably, the preparation method of the walnut protein soft nanoparticle emulsion comprises the following steps:

[0018] The walnut protein aqueous solution is heated and then stored at low temperature to obtain a walnut protein gel;

[0019] The walnut protein gel is sequentially sheared, high-pressure homogenized, diluted and the pH value is adjusted to acidic to obtain the walnut protein soft nanoparticles.

[0020] Preferably, the preparation method of the walnut protein fiber emulsion comprises the following steps:

[0021] The pH value of the walnut protein aqueous solution is adjusted to acidic in sequence, and then heated to obtain the walnut protein fiber emulsion.

[0022] Preferably, the oil-in-water reaction is carried out under shearing conditions; the shearing speed is 6000-6500 rpm and the time is 7-12 min.

[0023] The present invention also provides a double Pickering emulsion prepared by the preparation method described in the above technical scheme.

[0024] The present invention also provides the use of the double Pickering emulsion described in the above technical solution in the preparation of probiotic protein bars.

[0025] The present invention also provides a method for preparing a probiotic protein bar, comprising the following steps:

[0026] The sugar alcohol solution is boiled, mixed with the solid ingredients of the protein bar, and double Pickering emulsion is added, followed by chopping and cooling to obtain the probiotic protein bar;

[0027] The solid ingredients of the protein bar include protein powder and / or protein particles, and also include auxiliary materials;

[0028] The double Pickering emulsion is the double Pickering emulsion described in the above technical solution.

[0029] The present invention provides a preparation method of a double Pickering emulsion, comprising the following steps: adding a dispersion of probiotics to an oil phase solution, performing oil-in-water, and obtaining a first emulsion; mixing a walnut protein soft nanoparticle emulsion and a walnut protein nanofiber emulsion to obtain an aqueous phase solution; placing the first emulsion in the aqueous phase solution, performing water-in-oil, and obtaining a double Pickering emulsion. The preparation method of the present invention adopts the technology of water-in-oil-in-water (WOW), and utilizes the composite structure and stable skeleton support formed by the non-covalent interaction between the two components in the nano soft particle-fiber composite system (composite of walnut protein soft nanoparticles and walnut protein nanofibers). After the oil phase is added, the thickness of the encapsulation interface is increased, the steric hindrance distribution in the system is more uniform, and the emulsifier dispersion continuity is better, and it is not easy to break the emulsion, thereby forming a double Pickering emulsion with stable probiotic loading, and the prepared double Pickering emulsion has a stable structure and dimensional stability, thereby having the characteristics of enhanced thermal stability, strong mechanical stability and high loading rate.

[0030] The present invention also provides a method for preparing a probiotic protein bar, comprising the following steps: boiling a sugar alcohol solution, mixing it with auxiliary materials, adding a double Pickering emulsion, and sequentially chopping and refrigerating to obtain the probiotic protein bar; the double Pickering emulsion is the double Pickering emulsion described in the above technical solution. The preparation method of the present invention utilizes the thermal stability of the double Pickering emulsion described in the above technical solution and applies it to the probiotic protein bar, which can ensure the survival rate of probiotics during the preparation of the probiotic protein bar, and further improves the survival rate of probiotics during the preparation of the probiotic protein bar by about 400% compared with before the improvement by controlling the feeding and refrigeration process. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a microscope scan of the double Pickering emulsion described in Example 1;

[0032] Figure 2 This is a microscope scan of the double Pickering emulsion described in Example 2;

[0033] Figure 3 This is a microscope scan of the double Pickering emulsion described in Example 3;

[0034] Figure 4 This is a microscope scan of the double Pickering emulsion described in Comparative Example 1;

[0035] Figure 5 This is a microscope scan of the double Pickering emulsion described in Comparative Example 2;

[0036] Figure 6 This is a microscope scan of the double Pickering emulsion described in Comparative Example 3. DETAILED DESCRIPTION

[0037] The present invention provides a method for preparing a double Pickering emulsion, comprising the following steps:

[0038] Adding the dispersion of probiotics into the oil phase solution to perform water-in-oil process to obtain a first emulsion;

[0039] mixing walnut protein soft nanoparticle emulsion and walnut protein nanofiber emulsion to obtain an aqueous phase solution;

[0040] The first emulsion is placed in the aqueous phase solution to perform water-in-oil reaction to obtain a double Pickering emulsion.

[0041] In the present invention, unless otherwise specified, all preparation raw materials are commercially available products well known to those skilled in the art.

[0042] The present invention adds the dispersion of probiotics into the oil phase solution to perform oil-in-water reaction to obtain the first emulsion.

[0043] In the present invention, the dispersion of probiotics preferably includes probiotics and water, and the water is preferably purified water. In the present invention, the usage ratio of the probiotics to water is preferably (0.5-1) g:12 mL, more preferably (0.6-0.9) g:12 mL, and most preferably (0.7-0.8) g:12 mL. In the present invention, the preparation process of the dispersion of probiotics preferably includes dispersing the probiotics in water. The present invention does not have any special limitation on the dispersion process, and the process well known to those skilled in the art can be used.

[0044] In the present invention, the oil phase solution preferably includes a surfactant and a vegetable oil; the surfactant preferably includes one or more of Span, polyglycerol fatty acid ester, sucrose ester, mono- and diglycerol fatty acid ester and tartaric acid glyceride. When the surfactant is two or more of the above specific selections, the present invention does not have any special restrictions on the ratio of the above specific substances, and they can be mixed in any ratio. The vegetable oil preferably includes one or more of soybean oil, sunflower oil and peanut oil. When the vegetable oil is two or more of the above specific selections, the present invention does not have any special restrictions on the ratio of the above specific substances, and they can be mixed in any ratio. In the present invention, the volume ratio of the surfactant and the vegetable oil is preferably (1-2): (48-50), more preferably (1.3-1.6): (48.5-49.5). In the present invention, the preparation process of the oil phase solution preferably includes homogeneously mixing the surfactant and the vegetable oil to obtain the oil phase solution. The present invention does not have any special restrictions on the homogeneous mixing process, and the process well known to those skilled in the art can be used.

[0045] In the present invention, the volume ratio of the probiotic dispersion to the oil phase solution is preferably (0.8-1.2):(3.5-4.5), more preferably (0.9-1.2):(3.8-4.2), and most preferably 1:4.

[0046] In the present invention, the process of adding the dispersion of probiotics into the oil phase solution is preferably to add the dispersion of probiotics dropwise into the oil phase solution and shear to form an oil-in-water solution.

[0047] In the present invention, the water-in-oil reaction is preferably carried out under shearing conditions, and the shearing speed is preferably 5000-5500 rpm, more preferably 5100-5400 rpm, and most preferably 5200-5300 rpm; the time is preferably 4-10 min, and more preferably 5-8 min.

[0048] After obtaining the first emulsion, the present invention mixes the walnut protein soft nanoparticle emulsion and the walnut protein nanofiber emulsion to obtain an aqueous phase solution.

[0049] In the present invention, the concentration of walnut protein soft nanoparticles in the walnut protein soft nanoparticle emulsion is preferably 70-90%, more preferably 80-90%; the concentration of walnut protein nanofibers in the walnut protein nanofiber emulsion is preferably 50-70%, more preferably 60-70%. In the present invention, the volume ratio of the walnut protein soft nanoparticle emulsion and the walnut protein nanofiber emulsion is preferably (0-10): (10-0), and the volumes of the walnut protein soft nanoparticle emulsion and the walnut protein nanofiber emulsion are not 0, more preferably (2-8): (8-2), and most preferably (4-6): (6-4).

[0050] In the present invention, the preparation method of the walnut protein soft nanoparticle emulsion preferably comprises the following steps:

[0051] The walnut protein aqueous solution is heated and then stored at low temperature to obtain a walnut protein gel;

[0052] The walnut protein gel is sequentially sheared, high-pressure homogenized, diluted and the pH value is adjusted to acidic to obtain the walnut protein soft nanoparticles.

[0053] The invention heats the walnut protein aqueous solution and then stores it at a low temperature to obtain the walnut protein gel.

[0054] In the present invention, the mass percentage concentration of walnut protein powder in the walnut protein aqueous solution is preferably 1.5-2.5%, more preferably 1.8-2.2%, and most preferably 2%. In the present invention, the preparation of the walnut protein aqueous solution preferably includes mixing walnut protein powder and water to obtain the walnut protein powder aqueous solution. In the present invention, the water is preferably distilled water, the pH value of the distilled water is preferably 7.0, and the temperature of the distilled water is preferably 50° C. The present invention does not have any special restrictions on the mixing process, and the process well known to those skilled in the art can be used.

[0055] In the present invention, the heating temperature is preferably 80-95° C., more preferably 90° C.; the heating time is preferably 35-45 min, more preferably 40 min.

[0056] After the heating is completed, the present invention also preferably includes cooling, and the cooling is preferably cooled at room temperature for 30 minutes.

[0057] In the present invention, the low temperature storage is preferably storage at 4°C overnight.

[0058] After obtaining the walnut protein gel, the present invention sequentially shears, homogenizes under high pressure, dilutes and adjusts the pH value to acidic to obtain the walnut protein soft nanoparticles.

[0059] Before the shearing, the present invention also preferably includes breaking the walnut protein gel; the present invention does not have any special limitation on the breaking process, and the process well known to those skilled in the art can be used.

[0060] In the present invention, the shearing rotation speed is preferably 9000-10000 rpm, more preferably 10000 rpm; the shearing time is preferably 4.5-5.5 minutes, more preferably 5 minutes.

[0061] In the present invention, the pressure of the high-pressure homogenization is preferably 95-100 Pa, more preferably 100 MPa, and the time is preferably 8-12 min, more preferably 9-10 min. In the present invention, the number of high-pressure homogenization is preferably 1-3 times, more preferably 2 times.

[0062] In the present invention, the diluent used for the dilution is preferably distilled water. The mass percentage of walnut protein in the microgel dispersion obtained after the dilution is preferably 1.5-3%, more preferably 2.0wt%.

[0063] After the dilution is completed, the present invention also preferably includes ultrasonic degassing. The present invention does not have any special limitation on the process of ultrasonic degassing, and the process well known to those skilled in the art can be used.

[0064] In the present invention, the pH adjusting agent used to adjust the pH value is preferably an acid solution or an alkali solution; the acid solution is preferably a hydrochloric acid solution with a concentration of 0.1 mol / L, and the alkali solution is preferably a sodium hydroxide solution with a concentration of 0.1 mol / L. In the present invention, the pH value of the solution obtained after adjusting the pH value is preferably 3.9-4.2, more preferably 4.0.

[0065] In the present invention, the preparation method of the walnut protein fiber emulsion comprises the following steps:

[0066] The pH value of the walnut protein aqueous solution is adjusted to acidic in sequence, and then heated to obtain the walnut protein fiber emulsion.

[0067] In the present invention, the mass percentage concentration of walnut protein in the walnut protein aqueous solution is preferably 1.5-3%, more preferably 2.0wt%. In the present invention, the preparation of the walnut protein aqueous solution preferably includes mixing walnut protein powder and water to obtain the walnut protein powder aqueous solution. In the present invention, the water is preferably distilled water, the pH value of the distilled water is preferably 7.0, and the temperature of the distilled water is preferably 50°C. The present invention does not have any special restrictions on the mixing process, and the process well known to those skilled in the art can be used.

[0068] In the present invention, the pH adjusting agent used to adjust the pH value is preferably an acid solution or an alkali solution; the acid solution is preferably a hydrochloric acid solution with a concentration of 0.1 mol / L, and the alkali solution is preferably a sodium hydroxide solution with a concentration of 0.1 mol / L. In the present invention, the pH value of the solution obtained after adjusting the pH value is preferably 2 to 2.2, more preferably 2.0.

[0069] In the present invention, the heating temperature is preferably 80-90° C., more preferably 85° C.; the heating time is preferably 20-26 h, more preferably 24 h.

[0070] The present invention has no special limitation on the mixing of the walnut protein soft nanoparticle emulsion and the walnut protein nanofiber emulsion, and the mixing can be carried out by a process well known to those skilled in the art.

[0071] After obtaining the aqueous phase solution, the present invention places the first emulsion in the aqueous phase solution to perform oil-in-water reaction to obtain a double Pickering emulsion.

[0072] In the present invention, the process of placing the first emulsion in the aqueous phase solution is preferably to drop the first emulsion in the aqueous phase solution, and the dropping is preferably to drop by drop and shear to form an oil-in-water solution.

[0073] In the present invention, the oil-in-water reaction is preferably carried out under shearing conditions, and the shearing speed is preferably 6000-6500 rpm, more preferably 6100-6400 rpm, and most preferably 6200-6300 rpm; the time is preferably 7-12 min, and more preferably 8-10 min.

[0074] The present invention also provides a double Pickering emulsion prepared by the preparation method described in the above technical scheme.

[0075] In the present invention, the double Pickering emulsion preferably comprises a dispersion medium and probiotic microcapsules dispersed in the dispersion medium;

[0076] The probiotic microcapsule preferably comprises probiotics and an oil phase coating layer and a water phase coating layer sequentially coated on the outer surface of the probiotics.

[0077] The present invention also provides the use of the double Pickering emulsion described in the above technical solution in the preparation of probiotic protein bars.

[0078] The present invention also provides a method for preparing a probiotic protein bar, comprising the following steps:

[0079] The sugar alcohol solution is boiled, mixed with the solid ingredients of the protein bar, and double Pickering emulsion is added, followed by chopping and cooling to obtain the probiotic protein bar;

[0080] The solid ingredients of the protein bar include protein powder and / or protein particles, and also include auxiliary materials;

[0081] The double Pickering emulsion is the double Pickering emulsion described in the above technical solution.

[0082] The invention prepares the sugar alcohol solution, mixes it with the solid ingredients of the protein bar, adds the double Pickering emulsion, and sequentially performs chopping and refrigeration to obtain the probiotic protein bar.

[0083] In the present invention, the sugar alcohol solution preferably includes sugar alcohol, sunflower oil, phospholipids and water; the volume ratio of the sugar alcohol, sunflower oil, phospholipids and water is preferably (32-35): (2-3): (1-2): (4-10), more preferably (33-34): (2.3-2.6): (1.3-1.6): (6-8).

[0084] In the present invention, the boiling temperature is preferably 100-110° C., more preferably 100-105° C., and the boiling time is preferably 1-3 min, more preferably 2 min.

[0085] In the present invention, the protein bar solid ingredients include protein powder and / or protein particles, more preferably include protein powder and protein particles; the protein powder is preferably soy protein powder and whey protein powder, and the protein particles are preferably soy protein particles. When the protein bar solid ingredients include soy protein powder, whey protein fraction and soy protein particles, the mass ratio of the soy protein powder, whey protein fraction and soy protein particles is preferably (18-26): (6-12): (2-5), more preferably (20-23): (8-10): (3-4).

[0086] In the present invention, the protein bar solid ingredients also include auxiliary materials, and the auxiliary materials preferably include avocado powder, yam powder, taro powder, peanut crumbs and compound seasonings; the mass ratio of the avocado powder, yam powder, taro powder, peanut crumbs and compound seasonings is preferably (3-4): (3-9): (2-4): (1-2), and more preferably (3.4-3.6): (5-7): (2.5-3.5): (1.2-1.6).

[0087] In the present invention, the mass ratio of the soy protein powder to the avocado powder is preferably (18-26):(3-4).

[0088] In the present invention, the mixing with the protein bar solid ingredients is preferably to add the sugar alcohol solution obtained after the boiling into the protein bar solid ingredients for chopping. The present invention does not have any special limitation on the chopping process, and the process well known to those skilled in the art can be used.

[0089] In the present invention, when the double Pickering emulsion is added, the temperature of the mixture obtained after mixing is preferably 65-72°C, more preferably 70°C.

[0090] In the present invention, the chopping speed is preferably 600-800 rpm, preferably 650-750 rpm; the time is preferably 1-3 min, more preferably 2 min. In the present invention, the temperature of the mixed liquid continues to decrease during the chopping process.

[0091] In the present invention, the refrigeration is preferably carried out by using a refrigeration device under stirring conditions; the stirring speed is preferably 600 to 800 rpm, more preferably 650 to 750 rpm. In the present invention, the target temperature of the refrigeration is preferably 45°C.

[0092] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0093] Example 1

[0094] Dissolve 5 g of walnut protein powder in 95 mL of distilled water with a pH value of 7.0 and a temperature of 50° C. until it is completely dissolved to obtain a walnut protein solution with a mass concentration of 5%;

[0095] The walnut protein solution was heated at 90° C. for 4 minutes, cooled at room temperature for 30 minutes, and stored at 4° C. overnight to obtain a walnut protein gel;

[0096] The walnut protein gel was broken up by a chopper, and then sheared by a high-speed shearing machine at 10000 rpm for 5 minutes. The obtained microgel particles were homogenized by a Micro fluidizer microjet high-pressure homogenizer at 100 MPa for 2 cycles, and diluted with distilled water to obtain a microgel dispersion with a mass percentage concentration of 2.0%;

[0097] After removing the foam in the microgel dispersion by ultrasonic degassing, the pH value was adjusted to 4.0 with a 0.1 mol / L HCl solution to obtain a walnut protein soft nanoparticle emulsion (with a concentration of 90 wt%);

[0098] Dissolve 2 g of walnut protein powder in 98 mL of distilled water with a pH value of 7.0 and a temperature of 50° C. until completely dissolved to obtain a walnut protein solution with a mass concentration of 2%;

[0099] After adjusting the pH value of the walnut protein solution to 2.0 with a hydrochloric acid solution having a concentration of 0.1 mol / L, heating the solution at 85° C. for 24 h to obtain a walnut protein nanofiber emulsion (with a concentration of 70 wt %);

[0100] Disperse 0.8 g of probiotics into 12 mL of purified water to obtain a probiotic aqueous solution;

[0101] Add 1.4 mL of Span to 48.5 mL of vegetable oil (specifically soybean oil) and mix well to obtain an oil phase solution;

[0102] Under shearing conditions (shearing speed is 5300 rpm), 12 mL of the probiotic aqueous solution is added dropwise into 50 mL of the oil phase solution to perform oil-in-water, to obtain a first emulsion;

[0103] Mixing 70 mL of the walnut protein soft nanoparticle emulsion and 70 mL of the walnut protein nanofiber emulsion to obtain an aqueous phase solution (the volume ratio of the walnut protein soft nanoparticle emulsion to the walnut protein nanofiber emulsion is 1:1);

[0104] Under shearing conditions (the shearing speed is 6000 rpm), 60 mL of the first emulsion is added dropwise into 140 mL of the aqueous phase solution to obtain a double Pickering emulsion;

[0105] Figure 1 is a microscope scan of the double Pickering emulsion, Figure 1 It can be seen that the probiotic oil-in-water solution forms microcapsules with uniform particle size and small particle size in the nano-microcapsule-fiber water phase system, with a high probiotic encapsulation rate and a reasonable emulsion structure.

[0106] Example 2

[0107] Reference Example 1, except that: 60 mL of the walnut protein soft nanoparticle emulsion and 80 mL of the walnut protein nanofiber emulsion are mixed to obtain an aqueous phase solution (the volume ratio of the walnut protein soft nanoparticle emulsion to the walnut protein nanofiber emulsion is 3:4), and a double Pickering emulsion is obtained. Figure 2 It can be seen that the probiotic oil-in-water solution in the nano-microcapsule-fiber water phase system has relatively good uniformity in particle size and a small amount of demulsified areas.

[0108] Example 3

[0109] Reference Example 1, except that: 80 mL of the walnut protein soft nanoparticle emulsion and 60 mL of the walnut protein nanofiber emulsion are mixed to obtain an aqueous phase solution (the volume ratio of the walnut protein soft nanoparticle emulsion to the walnut protein nanofiber emulsion is 4:3), and a double Pickering emulsion is obtained. Figure 3 It can be seen that the probiotic oil-in-water solution in the nano-microcapsule-fiber water phase system has relatively good uniformity in particle size and a small amount of demulsified areas.

[0110] Comparative Example 1

[0111] Referring to Example 1, the difference is that the volume ratio of the walnut protein soft nanoparticle emulsion and the walnut protein nanofiber emulsion is 10:0, and a double Pickering emulsion is obtained;

[0112] Figure 4is a microscope scan of the double Pickering emulsion, Figure 2 It can be seen that in the emulsion system, the particle size uniformity is poor, there are many demulsification areas, and the probiotic encapsulation rate is low.

[0113] Comparative Example 2

[0114] Referring to Example 1, the difference is that the volume ratio of the walnut protein soft nanoparticle emulsion to the walnut protein nanofiber emulsion is 0:10, and a double Pickering emulsion is obtained;

[0115] Figure 5 is a microscope scan of the double Pickering emulsion, Figure 3 It can be seen that in the emulsion system, the particle size uniformity is poor, there are more demulsification areas, and the probiotic encapsulation rate is low.

[0116] Comparative Example 3

[0117] Referring to Example 1, the difference is that the aqueous phase solution is replaced with a walnut protein solution with a mass concentration of 2% to obtain a double Pickering emulsion;

[0118] Figure 6 is a microscope scan of the double Pickering emulsion, Figure 4 It can be seen that there are fewer microcapsules formed in the emulsion, the structure is chaotic, and the probiotic encapsulation rate is low.

[0119] Test Case

[0120] Embedding rate test: 0.5 mL of the double Pickering emulsion described in Examples 1 to 2 and Comparative Examples 1 to 3 was added to 2 mL of petroleum ether and allowed to stand for 10 min. 1 mL of the supernatant was transferred to a vial at room temperature. After the organic phase was evaporated in a fume hood, 3.8 mL of anhydrous ethanol was added. The absorbance of the solution was detected at 266 nm and 274 nm. A standard curve was established using ethanol as the solvent for the oil phase. The absorbance value was correlated with the oil phase concentration to determine the free oil content. The embedding amount was calculated as shown in Formula 1:

[0121] Embedding rate (%) = (total oil phase content - free oil content) / total oil phase content × 100% Formula 1;

[0122] Heat stress test: 10 mL of the double Pickering emulsions described in Examples 1 to 2 and Comparative Examples 1 to 3 were incubated at 70°C for 5 min under natural cooling conditions, and 1 mL of the emulsion after heat shock and the original emulsion were taken respectively, and cultured at 37°C overnight after gradient dilution, and the plate counts were performed; the calculation formula of the heat shock survival rate is shown in Formula 2:

[0123] Heat shock survival rate = number of colonies after heat shock in the same volume / number of colonies in the same volume of original emulsion × 100% Formula 2;

[0124] The test results are shown in Table 1:

[0125] Table 1 Embedding efficiency and heat shock survival rate of the double Pickering emulsions described in Examples 1 to 2 and Comparative Examples 1 to 3

[0126]

[0127] Application Examples

[0128] 42g of the liquid part of the protein bar (components and component ratios are sugar alcohol: sunflower oil: phospholipids: water = 33:2:1:6) is boiled (the boiling temperature is 105°C and the time is 2min), and then added to 53g of solid ingredients (components and component ratios are soy protein powder: soy protein granules: whey protein powder: avocado powder: yam powder: taro powder: peanut crumbs: compound seasoning = 18:11:5:4:9:4:2) and chopped evenly. Then, 5g of the double Pickering emulsion described in Example 1 and Comparative Example 3 is added to the obtained mixture at 70°C, and after chopping at a speed of 800rpm for 2min, it is cooled to 45°C under stirring (rotation speed of 800rpm) using a refrigeration equipment, put into a feeding box, and enter the subsequent cutting assembly line to obtain a probiotic protein bar.

[0129] The survival rate of the probiotics in the probiotic protein bar was determined, and the calculation formula was shown in Formula 3:

[0130] Survival rate = finished product probiotic concentration (cfu / mg) / added emulsion probiotic concentration (cfu / mg) * 20 Formula 3;

[0131] The test results are shown in Table 2:

[0132] Table 2 Survival rate of probiotic protein bars prepared by double Pickering emulsions described in Example 1 and Comparative Example 3

[0133] Example Example 1 Comparative Example 3 Survival rate (%) 63.7 23.7

[0134] Comparative Example Application Example 1

[0135] 42g of the liquid part of the protein bar (components and component ratios are sugar alcohol: sunflower oil: phospholipid: water = 33:2:1:6) is boiled (boiling temperature is 105°C, time is 2min), and then added to 53g of solid ingredients (components and component ratios are soy protein powder: soy protein particles: whey protein powder: avocado powder: yam powder: taro powder: peanut crumbs: compound seasoning = 18:11:5:4:9:4:2) and chopped and mixed evenly, and 5g of the double Pickering emulsion described in Example 1 and Comparative Example 3 is added to the obtained mixture at 70°C, and after chopping and mixing at a speed of 800rpm for 2min, it is put into the feed box of the assembly line, and cooled on the subsequent cutting assembly line to obtain a probiotic protein bar;

[0136] Table 3 Survival rate of probiotic protein bars prepared by double Pickering emulsions described in Example 1 and Comparative Example 3

[0137] Example Example 1 Comparative Example 3 Survival rate (%) 58.2 21.0

[0138] Comparative Example 2

[0139] 42 g of the liquid portion of the protein bar after cooking (components and component ratios are sugar alcohol: sunflower oil: phospholipid: water = 33:2:1:6) and 58 g of all other ingredients (including the double Pickering emulsion described in Example 1 and Comparative Example 3) (components and component ratios are soy protein powder: soy protein particles: whey protein powder: avocado powder: yam powder: taro powder: peanut crumbs: compound seasoning: double Pickering emulsion = 20:11:5:4:9:4:2:5) are mixed, and then chopped at a speed of 800 rpm for 2 minutes and put into the feed box of the assembly line, and cooled on the subsequent cutting assembly line to obtain a probiotic protein bar;

[0140] The survival rate of the probiotic protein bar is shown in Table 3:

[0141] Table 3 Survival rate of probiotic protein bars prepared by double Pickering emulsions in Example 1 and Comparative Example 3

[0142] Example Example 1 Comparative Example 3 Survival rate (%) 28.8 12.7

[0143] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a double Pickering emulsion, characterized in that: The following steps are involved: Adding the dispersion of probiotics into the oil phase solution to perform water-in-oil process to obtain a first emulsion; mixing walnut protein soft nanoparticle emulsion and walnut protein nanofiber emulsion to obtain an aqueous phase solution; The first emulsion is placed in the aqueous phase solution to perform water-in-oil reaction to obtain a double Pickering emulsion.

2. The preparation method according to claim 1, characterized in that The ratio of probiotics to water in the probiotic dispersion is (0.5-1) g:12 mL; The oil phase solution includes a surfactant and a vegetable oil; The volume ratio of the surfactant to the vegetable oil is (1-2):(48-50).

3. The preparation method according to claim 2, characterized in that: The volume ratio of the probiotic dispersion to the oil phase solution is (0.8-1.2):(3.5-4.5); The water-in-oil reaction is carried out under shearing conditions, the shearing speed is 5000-5500 rpm, and the time is 4-10 minutes.

4. The preparation method according to claim 1, characterized in that: The volume ratio of the walnut protein soft nanoparticle emulsion to the walnut protein nanofiber emulsion is (0-10): (10-0), and the volumes of the peach protein soft nanoparticle emulsion and the walnut protein nanofiber emulsion are not 0; The mass percentage concentration of walnut protein soft nanoparticles in the walnut protein soft nanoparticle emulsion is 70-90%; The mass percentage concentration of the walnut protein nanofibers in the walnut protein nanofiber emulsion is 50-70%.

5. The preparation method according to claim 1 or 4, characterized in that: The preparation method of the walnut protein soft nanoparticle emulsion comprises the following steps: The walnut protein aqueous solution is heated and then stored at low temperature to obtain a walnut protein gel; The walnut protein gel is sequentially sheared, high-pressure homogenized, diluted and the pH value is adjusted to acidic to obtain the walnut protein soft nanoparticles.

6. The preparation method according to claim 1 or 4, characterized in that: The preparation method of the walnut protein fiber emulsion comprises the following steps: The pH value of the walnut protein aqueous solution is adjusted to acidic in sequence, and then heated to obtain the walnut protein fiber emulsion.

7. The preparation method according to claim 6, characterized in that: The oil-in-water reaction is carried out under shearing conditions; the shearing speed is 6000-6500 rpm and the time is 7-12 minutes.

8. The double Pickering emulsion prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the double Pickering emulsion according to claim 8 in the preparation of probiotic protein bars.

10. A method for preparing a probiotic protein bar, characterized in that: The following steps are involved: The sugar alcohol solution is boiled, mixed with the solid ingredients of the protein bar, and double Pickering emulsion is added, followed by chopping and cooling to obtain the probiotic protein bar; The solid ingredients of the protein bar include protein powder and / or protein particles, and also include auxiliary materials; The double Pickering emulsion is the double Pickering emulsion according to claim 8.

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