High-stability double emulsion as well as preparation method and application thereof

Abstract

The invention discloses a high-stability double emulsion as well as a preparation method and application thereof, and belongs to the technical field of food. The inner water phase comprises a water-soluble active component, grain nanoparticles, araboxylan and water, and based on the total mass of the inner water phase, the mass percentage content of the grain nanoparticles is 0.5-5%, and the mass percentage content of the araboxylan is 0.1-1%; the oil phase comprises an oil-soluble active ingredient and liquid oil, and the oil-soluble active ingredient comprises lutein. According to the invention, grain nanoparticles and arabinoxylan are introduced into an internal water phase, and the grain nanoparticles and arabinoxylan are subjected to electrostatic and hydrogen bond interaction, so that the grain nanoparticles can be better adsorbed on a water-oil interface, and the stability of the double emulsion is further improved; the micro-fluidic technology is combined in the preparation process, the double emulsion with good and stable particle size uniformity can be formed, the encapsulation stability and the slow release effect of the active ingredients are improved, and the storage life is prolonged.

Description

Technical Field

[0001] The present invention relates to the field of food technology, and in particular to a highly stable double emulsion and a preparation method and application thereof. Background Art

[0002] Lutein is a natural carotenoid that is widely found in green vegetables, fruits, and certain marine organisms (such as seaweed, shrimp, crab, etc.). It has a strong antioxidant effect, can scavenge reactive oxygen species, reduce oxidative stress, and protect cells from damage; lutein may have anti-inflammatory effects and help alleviate the symptoms of certain inflammatory diseases. However, lutein is a fat-soluble active ingredient, and its solubility is very different from that of water-soluble active ingredients, making it difficult to compound lutein with water-soluble active ingredients, which to a certain extent limits its application in food. Therefore, the compounding of lutein with water-soluble active ingredients requires a stable delivery dosage form to achieve efficient co-delivery to enhance the bioavailability of these two ingredients.

[0003] In recent years, double emulsions have attracted widespread attention for the delivery of oil-soluble and water-soluble active ingredients. Double emulsions are emulsion systems in which dispersed phase droplets contain smaller droplets of another type. While the two-membrane, three-phase structure of double emulsions allows the coexistence of oil-soluble lutein and water-soluble active ingredients without mutual interference, existing double emulsions suffer from poor stability, prone to instability during processing and storage, including phase separation, droplet flocculation, and Ostwald ripening. Summary of the Invention

[0004] Based on the defects of the prior art, the purpose of the present invention is to provide a highly stable double emulsion and a preparation method and application thereof.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] In a first aspect, the present invention provides a highly stable double emulsion comprising an inner aqueous phase, an oil phase, and an outer aqueous phase, wherein the inner aqueous phase comprises a water-soluble active ingredient, cereal nanoparticles, arabinoxylan, and water, and based on the total mass of the inner aqueous phase, the mass percentage of the cereal nanoparticles is 0.5-5%, and the mass percentage of the arabinoxylan is 0.1-1%;

[0007] The oil phase includes an oil-soluble active ingredient and liquid oil, and the oil-soluble active ingredient includes lutein;

[0008] The external aqueous phase includes water.

[0009] As a preferred embodiment of the highly stable double emulsion of the present invention, the volume ratio of the inner water phase to the oil phase is (0.1-1):1.

[0010] As a preferred embodiment of the highly stable double emulsion of the present invention, the ratio between the volume of the external aqueous phase and the total volume of the internal aqueous phase and the oil phase is (1-5):1.

[0011] As a preferred embodiment of the highly stable double emulsion of the present invention, the cereal nanoparticles include at least one of corn nanoparticles, wheat nanoparticles, and rice nanoparticles.

[0012] As a preferred embodiment of the highly stable double emulsion of the present invention, the cereal nanoparticles are prepared by the following method: crushing cereals, adding water for grinding, filtering, sterilizing, and freeze-drying to obtain cereal nanoparticles.

[0013] As a preferred embodiment of the highly stable double emulsion of the present invention, the inner aqueous phase is prepared by the following method:

[0014] A1. Dispersing the cereal nanoparticles in water to prepare a nanoparticle suspension;

[0015] A2. adding a water-soluble active ingredient to the nanoparticle suspension and mixing to obtain a nanoparticle suspension loaded with the water-soluble active ingredient;

[0016] A3. Dissolve arabinoxylan in water to prepare an arabinoxylan solution, mix the nanoparticle suspension loaded with water-soluble active ingredients and the arabinoxylan solution, and perform ultrasonic treatment to obtain an inner aqueous phase.

[0017] As a preferred embodiment of the highly stable double emulsion of the present invention, the external aqueous phase further comprises composite nanogel particles, which are prepared by the following method: dropping a calcium chloride solution into an aqueous solution containing inulin and sodium alginate, stirring, crushing, centrifuging, washing, and drying to obtain the composite nanogel particles.

[0018] Furthermore, based on the total mass of the external aqueous phase, the mass percentage of the composite nanogel particles is 0.05-2%.

[0019] As a preferred embodiment of the highly stable double emulsion of the present invention, the oil phase further includes natural wax, the mass percentage of the natural wax in the oil phase is 1 to 10%, and the natural wax includes at least one of beeswax, palm wax, rice bran wax, and soybean wax.

[0020] As a preferred embodiment of the highly stable double emulsion of the present invention, the liquid oil includes at least one of soybean oil, rapeseed oil, peanut oil, cottonseed oil, sunflower oil, sesame oil, camellia oil, linseed oil, corn oil, rice bran oil, olive oil, coconut oil, and palm oil.

[0021] In a second aspect, the present invention provides a method for preparing the highly stable double emulsion as described in the first aspect, comprising the following steps:

[0022] S1. Add the inner aqueous phase dropwise into the oil phase under stirring, and shear and homogenize to obtain a primary emulsion;

[0023] S2. The primary emulsion and the external aqueous phase are mixed through a microfluidic emulsification device to obtain a double emulsion.

[0024] As a preferred embodiment of the method for preparing the highly stable double emulsion of the present invention, in step S1, the shearing temperature is 40-65° C., the rotation speed is 10,000-15,000 rpm, and the time is 2-4 minutes.

[0025] As a preferred embodiment of the method for preparing a highly stable double emulsion of the present invention, in the microfluidic emulsification device in step S2, the flow rate ratio of the primary emulsion to the external aqueous phase is 1:(1-5).

[0026] In a third aspect, the present invention provides a use of the highly stable double emulsion as described in the first aspect in preparing food.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention introduces cereal nanoparticles and arabinoxylan into the inner water phase. The cereal nanoparticles interact with the arabinoxylan through electrostatic and hydrogen bonds, so that the cereal nanoparticles can be better adsorbed on the water-oil interface, thereby improving the stability of the double emulsion.

[0029] The present invention combines microfluidic technology in the preparation process, which can form a double emulsion with good particle size uniformity and stability, improve the encapsulation stability and sustained release effect of the active ingredients, and extend the shelf life. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A longitudinal cross-sectional view of the microfluidic emulsification device provided by the present invention;

[0031] Figure 2 A partial cross-sectional view of the microfluidic emulsification device provided by the present invention;

[0032] Figure 3 is a three-dimensional diagram of the microfluidic emulsification device of the present invention;

[0033] Figure 4 A three-dimensional view of the microfluidic emulsification device of the present invention from another perspective;

[0034] Figure 5 A schematic diagram of the connection between the first branch flow channel, the second branch flow channel and the connecting flow channel provided by the present invention. DETAILED DESCRIPTION

[0035] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below with reference to specific embodiments and comparative examples. The purpose is to provide a detailed understanding of the content of the present invention, but not to limit the present invention. All other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present invention.

[0036] In a first aspect, the present invention provides a highly stable double emulsion comprising an inner aqueous phase, an oil phase, and an outer aqueous phase, wherein the inner aqueous phase comprises a water-soluble active ingredient, cereal nanoparticles, arabinoxylan, and water, and based on the total mass of the inner aqueous phase, the mass percentage of the cereal nanoparticles is 0.5-5%, and the mass percentage of the arabinoxylan is 0.1-1%;

[0037] The oil phase includes an oil-soluble active ingredient and liquid oil, and the oil-soluble active ingredient includes lutein;

[0038] The external aqueous phase includes water.

[0039] The present invention introduces cereal nanoparticles and arabinoxylan into the inner water phase. The cereal nanoparticles interact with the arabinoxylan through electrostatic and hydrogen bonds, so that the cereal nanoparticles can be better adsorbed on the water-oil interface, thereby improving the stability of the double emulsion.

[0040] Based on the total mass of the inner aqueous phase, the mass percentage of the cereal nanoparticles can be 0.5%, 1%, 2%, 3%, 4%, 5% or a range consisting of any two groups of values therein, and the mass percentage of the arabinoxylan is 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1% or a range consisting of any two groups of values therein.

[0041] In some embodiments, based on the total mass of the inner aqueous phase, the mass percentage of the cereal nanoparticles is 1-3%, and the mass percentage of the arabinoxylan is 0.5-0.8%.

[0042] In some embodiments, the volume ratio of the inner water phase to the oil phase is (0.1-1): 1. For example, the volume ratio of the inner water phase to the oil phase can be 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, or a range consisting of any two mass ratios therein.

[0043] The volume ratio of the inner water phase to the oil phase is preferably (0.3-0.5):1.

[0044] In some embodiments, the ratio of the volume of the external aqueous phase to the total volume of the internal aqueous phase and the oil phase is (1-5): 1. Exemplarily, the ratio of the volume of the external aqueous phase to the total volume of the internal aqueous phase and the oil phase can be 1:1, 2:1, 3:1, 4:1, 5:1, or a range consisting of any two of these mass ratios.

[0045] The ratio between the volume of the external aqueous phase and the total volume of the internal aqueous phase and the oil phase is preferably (1-3):1.

[0046] In some embodiments, the cereal nanoparticles include at least one of corn nanoparticles, wheat nanoparticles, and rice nanoparticles.

[0047] In some embodiments, the cereal nanoparticles are prepared by the following method: crushing cereals, adding water for grinding, filtering, sterilizing, and freeze-drying to obtain cereal nanoparticles.

[0048] In some embodiments, the internal aqueous phase is prepared by the following method:

[0049] A1. Dispersing the cereal nanoparticles in water to prepare a nanoparticle suspension;

[0050] A2. adding a water-soluble active ingredient to the nanoparticle suspension and mixing to obtain a nanoparticle suspension loaded with the water-soluble active ingredient;

[0051] A3. Dissolve arabinoxylan in water to prepare an arabinoxylan solution, mix the nanoparticle suspension loaded with water-soluble active ingredients and the arabinoxylan solution, and perform ultrasonic treatment to obtain an inner aqueous phase.

[0052] In step A3, the mass percentage of arabinoxylan in the arabinoxylan solution is 1-5%, for example, the mass percentage of arabinoxylan in the arabinoxylan solution is 1%, 2%, 3%, 4%, 5%, or a range consisting of any two groups of values therein.

[0053] In step A3, the ultrasonic treatment is carried out under the following conditions: power 200-500 W, time 20-40 min.

[0054] Exemplarily, based on the total mass of the inner aqueous phase, the mass percentage of the cereal nanoparticles can be 1%, 2%, 3%, 4%, 5% or a range consisting of any two groups of values therein; the mass percentage of the arabinoxylan can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1% or a range consisting of any two groups of values therein.

[0055] In some embodiments, the water-soluble active ingredient may be at least one of anthocyanidins, tea polyphenols, ascorbic acid, and ferulic acid.

[0056] In some embodiments, based on the total mass of the internal aqueous phase, the mass percentage of the water-soluble active ingredient is 0.01-2%.

[0057] In some embodiments, the external aqueous phase further comprises composite nanogel particles, which are prepared by the following method: dropping a calcium chloride solution into an aqueous solution containing inulin and sodium alginate, stirring, crushing, centrifuging, washing, and drying to obtain composite nanogel particles.

[0058] The present invention introduces composite nanogel particles into the external aqueous phase. The composite nanogel particles are formed by cross-linking inulin, sodium alginate and calcium chloride. The composite nanogel particles can be adsorbed on the oil-water interface and form a coating layer, thereby effectively preventing collision and aggregation between adjacent droplets in the double emulsion and improving the stability of the double emulsion.

[0059] The inventors have found through research that inulin itself does not have strong adsorption capacity, but the introduction of inulin can improve the adsorption performance of gel particles. This may be due to the interaction between the polyhydroxy structure of inulin and the carboxylate groups of alginate, which improves the surface wettability of the composite nanogel particles, making the composite nanogel particles more easily adsorbed at the oil-water interface, thereby effectively preventing collision and aggregation between adjacent droplets in the double emulsion and improving the stability of the double emulsion.

[0060] Based on the total mass of the external aqueous phase, the mass percentage of the composite nanogel particles is 0.05-2%. Exemplarily, the mass percentage of the composite nanogel particles can be 0.05%, 0.1%, 0.2%, 0.3%, 0.5%, 0.7%, 1%, 1.5%, 2%, or a range consisting of any two of these values.

[0061] The inventors have found through research that when the mass percentage of the composite nano-gel particles in the external aqueous phase is 0.1-0.5%, the stability of the double emulsion is better.

[0062] In the aqueous solution containing inulin and sodium alginate, the mass percentage of the sodium alginate is 0.2-1%, and the mass ratio of the inulin to the sodium alginate is (0.1-1):1.

[0063] The volume ratio of the aqueous solution containing inulin and sodium alginate to the calcium chloride solution is (3-5):1.

[0064] The mass percentage of calcium chloride in the calcium chloride solution is 0.5-2%.

[0065] The inventors have found through research that when the mass ratio of inulin to the sodium alginate is (0.3-0.8):1, the droplet size of the double emulsion is smaller, and the prepared composite nanogel particles can effectively swell, aggregate and mature the droplets, thereby improving the storage stability and freeze-thaw stability of the double emulsion.

[0066] In some embodiments, the external aqueous phase is prepared by the following method:

[0067] B1. dissolving inulin and sodium alginate in water to obtain an aqueous solution containing inulin and sodium alginate;

[0068] B2. Under stirring conditions, add the calcium chloride solution dropwise to the aqueous solution containing inulin and sodium alginate. After the addition is completed, continue stirring for 10 to 30 minutes, use an ultrasonic cell disruptor to disrupt the cells, centrifuge and wash, and dry to obtain composite nanogel particles.

[0069] In step B2, the power of the crushing process is 200-300 W, and the time of the crushing process is 10-30 minutes.

[0070] In step B2, the calcium chloride solution is added at a rate of 1 to 3 mL / min.

[0071] The present invention adds an aqueous solution containing inulin and sodium alginate dropwise into a calcium chloride solution to form relatively large spherical gel particles, which are crushed to nanometer level by crushing at a power of 200-300W.

[0072] In some embodiments, the oil phase further comprises natural wax, the mass percentage of the natural wax in the oil phase is 0.5-5%, and the natural wax comprises at least one of beeswax, palm wax, rice bran wax, and soybean wax.

[0073] For example, the mass percentage of the natural wax in the oil phase can be 0.5%, 1%, 2%, 3%, 4%, 5% or a range consisting of any two groups of values therein.

[0074] The mass percentage of the beeswax in the oil phase is preferably 1-2%.

[0075] The inventors have discovered through research that introducing an appropriate amount of natural wax into the oil phase can effectively reduce the oil-water interfacial tension, promote droplet breakage during homogenization and microfluidic emulsification, and form droplets of smaller particle size; natural wax can be adsorbed at the interface, thereby improving the stability of the double emulsion.

[0076] In some embodiments, the liquid oil comprises at least one of soybean oil, rapeseed oil, peanut oil, cottonseed oil, sunflower oil, sesame oil, camellia oil, linseed oil, corn oil, rice bran oil, olive oil, coconut oil, and palm oil.

[0077] In a second aspect, the present invention provides a method for preparing the highly stable double emulsion as described in the first aspect, comprising the following steps:

[0078] S1. Add the inner aqueous phase dropwise into the oil phase under stirring, and shear and homogenize to obtain a primary emulsion;

[0079] S2. The primary emulsion and the external aqueous phase are mixed through a microfluidic emulsification device to obtain a double emulsion.

[0080] In one embodiment, in step S1, the shearing temperature is 40-65° C., the rotation speed is 10,000-15,000 rpm, and the time is 2-4 minutes.

[0081] In some embodiments, in step S1, the stirring speed is 500-1000 r / min, and the dripping rate of the inner aqueous phase is 1-5 mL / min.

[0082] In some embodiments, in the microfluidic emulsification device of step S2, the ratio between the flow rate of the primary emulsion and the total flow rate of the external aqueous phase is 1:(1-5).

[0083] The present invention combines microfluidic technology in the preparation process. By controlling the flow rate of the primary emulsion and the flow rate of the external aqueous phase, a double emulsion with good particle size uniformity and stability can be formed, thereby improving the encapsulation stability and sustained release effect of the active ingredients and extending the shelf life.

[0084] In some embodiments, see Figures 1 to 5 The microfluidic emulsification device includes an emulsification component and a collector 8. The emulsification component includes a first feed port 1, a second feed port 2, a first main channel 3, a second main channel 4, and at least one group of emulsification units. The first feed port 1 is connected to the first main channel 3. The emulsification unit includes a first branch channel 5 and a second branch channel 6. One end of the first branch channel 5 is connected to the first main channel 3, and the other end of the first branch channel 5 is connected to the collector 8. One end of the second branch channel 6 is connected to the second main channel 4. The first branch channel 5 and the second branch channel 6 are connected through at least one connecting channel 7. A discharge port 9 is provided at the bottom of the collector 8.

[0085] The present invention adopts a microfluidic emulsification device to achieve more efficient and controllable mixed emulsification of the primary emulsion and the external aqueous phase, can improve the emulsification efficiency and stability, and can achieve continuous production of double emulsions.

[0086] Specifically, a micro-disperser 10 is provided between the second main channel 3 and the second feed port 2 , the feed end of the micro-disperser 10 is communicated with the second feed port 2 , and the discharge end of the micro-disperser 10 is communicated with the second main channel 3 .

[0087] Specifically, a first flow regulating valve 11 is provided on the first main flow channel 3 , and the first flow regulating valve 11 is located between the first branch flow channel 5 and the first feed inlet 1 .

[0088] Specifically, a second flow regulating valve 12 is provided on the second main flow channel 4 , and the second flow regulating valve 12 is located between the second branch flow channel 6 and the second feed port 2 .

[0089] Specifically, a pressure sensor 13 is provided on the first branch flow channel 5, and the pressure sensor 13 is located between the connecting flow channel 7 and the collector 8. The pressure of the fluid is monitored by the pressure sensor 13. The flow state of the fluid in each flow channel can be monitored and adjusted in real time through the pressure sensor 13, the first flow regulating valve 11 and the second flow regulating valve 12 to ensure the stability of the emulsification process.

[0090] Specifically, the microfluidic emulsification device further includes a shell 14 , a first feed port 1 and a second feed port 2 respectively pass through the upper wall of the shell 14 , a discharge port 9 passes through the lower wall of the shell 14 , and the emulsification unit and the collector 8 are located inside the shell 1 .

[0091] Specifically, the other end of the second branch flow channel 6 is closed.

[0092] Specifically, in the emulsification unit, the number of the first branch flow channels 5 and the number of the second branch flow channels 6 are both one, and the first branch flow channel 5 is connected to the second branch flow channel 6 through at least three parallel and equally spaced connecting flow channels 7 .

[0093] Specifically, in the emulsification unit, the number of first branch channels 5 is one, the number of second branch channels 6 is two, the first branch channel 5 is located between the two second branch channels 6, and the connecting channels 7 are arranged in two rows, one row of connecting channels is arranged between the first branch channel 5 and one of the second branch channels 6, and the other row of connecting channels is arranged between the first branch channel 5 and the other second branch channel 6. The two rows of connecting channels are arranged symmetrically, and each row of connecting channels includes at least three parallel and equally spaced connecting channels 7.

[0094] Specifically, in the emulsification unit, the first branch flow channel 5 is located below the second branch flow channel 6 .

[0095] Specifically, the angle between the communication channel 7 and the first branch channel 5 is 10 to 90 degrees, and the angle between the communication channel 7 and the second branch channel 6 is 10 to 90 degrees.

[0096] The present invention has no particular limitation on the number of emulsification assemblies and the number of emulsification units.

[0097] Specifically, the number of the emulsifying components can be 1, 2, 3, 4, or a range consisting of any two groups of values. For example, the number of the emulsifying components is 2, and the two emulsifying components are symmetrically arranged on both sides of the collector 8.

[0098] Specifically, the number of the emulsification units can be 2, 3, 4, 5, 6, or a range consisting of any two groups of values. For example, the number of the emulsification units is 6, and the six emulsification units are divided into two groups, each with 3 emulsification units. The two groups of emulsification units are arranged in sequence along the longitudinal direction, and the emulsification units in each group are evenly spaced along the transverse direction.

[0099] It is understood that the present invention can design the size and shape of each flow channel according to the desired droplet size in the double emulsion, the fluid properties of the primary emulsion, the fluid properties of the external aqueous phase, etc. For example, the inner diameters of the first main flow channel 3 and the second main flow channel 4 can each independently be 100 to 500 μm, and the inner diameters of the first branch flow channel 5, the second branch flow channel 6, and the connecting flow channel 7 can each independently be 10 to 100 μm.

[0100] It can be understood that the first feed port 1 can be connected to a first fluid pump outside the delivery pipeline, and the second feed port 2 can be connected to a second fluid pump outside the delivery pipeline.

[0101] During use, the external aqueous phase 16 is input into the second feed port 2 through the second fluid pump and the delivery pipeline, and the primary emulsion 15 is input into the first feed port 1 through the first fluid pump and the delivery pipeline. The primary emulsion 15 flows through the first feed port 1 and the first main channel 3 and then enters the first branch channel 5. The external aqueous phase 16 flows through the second feed port 2, the second main channel 4, the second branch channel 6 and the connecting channel 7 in sequence and then enters the first branch channel 5, so that the primary emulsion 15 and the external aqueous phase 16 merge in the first branch channel 5. The flow rate of the fluid in each channel is adjusted by the first flow regulating valve 11 and the second flow regulating valve 12, so that the primary emulsion 15 and the external aqueous phase 16 merge to form emulsion droplets 17 with controllable particle size, and the emulsified product flows into the collector 8 for collection.

[0102] In a third aspect, the present invention provides a use of the highly stable double emulsion as described in the first aspect in preparing food.

[0103] The present invention provides the following examples to facilitate understanding of the present invention. The present invention provides these examples but is not intended to limit the scope of the claims.

[0104] Unless otherwise specified, the components and raw materials used in the examples and comparative examples of the present invention are all commercially available raw materials, and the components and raw materials used in each parallel experiment are all of the same kind.

[0105] The microfluidic emulsification device used in the following examples and comparative examples is as follows: Figures 1-2 As shown, the microfluidic emulsification device includes an emulsification component and a collector 8, the emulsification component includes a first feed port 1, a second feed port 2, a first main channel 3, a second main channel 4, and at least one group of emulsification units, the first feed port 1 is connected to the first main channel 3, the emulsification unit includes a first branch channel 5 and a second branch channel 6, one end of the first branch channel 5 is connected to the first main channel 3, the other end of the first branch channel 5 is connected to the collector 8, one end of the second branch channel 6 is connected to the second main channel 4, the other end of the second branch channel 6 is closed, and a discharge port 9 is provided at the bottom of the collector 8.

[0106] In the emulsification unit, there is one first branch channel 5 and two second branch channels 6. The first branch channel 5 is located between the two second branch channels 6. The connecting channels 7 are arranged in two rows, one row of connecting channels is arranged between the first branch channel 5 and one of the second branch channels 6, and the other row of connecting channels is arranged between the first branch channel 5 and the other second branch channel 6. The two rows of connecting channels are arranged symmetrically, and each row of connecting channels includes three parallel and equally spaced connecting channels 7; the first branch channel 5 is located below the second branch channel 6; the angle between the connecting channel 7 and the first branch channel 5 is 90°, and the angle between the connecting channel 7 and the second branch channel 6 is 90°.

[0107] A micro-disperser 10 is provided between the second main channel 3 and the second feed port 2 . The feed end of the micro-disperser 10 is communicated with the second feed port 2 , and the discharge end of the micro-disperser 10 is communicated with the second main channel 3 .

[0108] A first flow regulating valve 11 is provided on the first main channel 3, and the first flow regulating valve 11 is located between the first branch channel 5 and the first feed port 1; a second flow regulating valve 12 is provided on the second main channel 4, and the second flow regulating valve 12 is located between the second branch channel 6 and the second feed port 2; a pressure sensor 13 is provided on the first branch channel 5, and the pressure sensor 13 is located between the connecting channel 7 and the collector 8.

[0109] The microfluidic emulsification device further includes a housing 14 , a first feed port 1 and a second feed port 2 respectively pass through the upper wall of the housing 14 , a discharge port 9 passes through the lower wall of the housing 14 , and an emulsification unit and a collector 8 are located inside the housing 1 .

[0110] The number of the emulsifying components is two, and the two emulsifying components are symmetrically arranged on both sides of the collector 8.

[0111] The number of the emulsification units is 6, and the six emulsification units are divided into two groups, with 3 emulsification units in each group. The two groups of emulsification units are arranged in sequence along the longitudinal direction, and the emulsification units in each group are distributed at equal intervals along the transverse direction.

[0112] It is understood that the present invention can design the size and shape of each flow channel based on the desired droplet size in the double emulsion, the fluid properties of the primary emulsion, the fluid properties of the external aqueous phase, etc. For example, the inner diameters of the first main flow channel 3 and the second main flow channel 4 are both 300 μm, and the inner diameters of the first branch flow channel 5, the second branch flow channel 6, and the connecting flow channel 7 are all 50 μm.

[0113] It can be understood that the first feed port 1 can be connected to a first fluid pump outside the delivery pipeline, and the second feed port 2 can be connected to a second fluid pump outside the delivery pipeline.

[0114] Example 1

[0115] An embodiment of the highly stable double emulsion of the present invention, wherein the preparation method of the highly stable double emulsion is as follows:

[0116] (1) Preparation of internal aqueous phase

[0117] The corn was crushed and passed through a 300-mesh sieve to obtain corn powder; the corn powder was transferred to a grinder ( RESEARCH LAB), adding deionized water for ultrafine grinding for 1.5 h, the mass ratio of corn powder to deionized water is 1:10, filtering, sterilizing, and freeze-drying to obtain corn nanoparticles;

[0118] Prepare the following components of the internal aqueous phase in percentage by mass: 2% corn nanoparticles, 1% water-soluble active ingredient, 0.5% water-soluble arabinoxylan, and the balance deionized water; wherein the water-soluble active ingredient is ascorbic acid;

[0119] Dissolving water-soluble arabinoxylan in a portion of deionized water by stirring to prepare an arabinoxylan solution, wherein the mass percentage of arabinoxylan in the arabinoxylan solution is 5%;

[0120] dispersing the corn nanoparticles in the remaining deionized water to obtain a nanoparticle suspension; adding a water-soluble active ingredient to the nanoparticle suspension and mixing them uniformly to obtain a nanoparticle suspension loaded with the water-soluble active ingredient;

[0121] The arabinoxylan solution was added to the nanoparticle suspension loaded with the water-soluble active ingredient, and ultrasonically treated at a power of 300 W for 30 minutes to obtain an inner aqueous phase.

[0122] (2) Preparation of oil phase

[0123] Beeswax is dissolved in soybean oil, lutein is added, and stirred evenly to form an oil phase, wherein the mass percentage of the lutein in the oil phase is 1%, and the mass percentage of the beeswax in the oil phase is 5%.

[0124] (3) Preparation of external aqueous phase

[0125] Dissolving inulin and sodium alginate in water to obtain an aqueous solution containing inulin and sodium alginate, wherein the mass percentage of sodium alginate in the aqueous solution containing inulin and sodium alginate is 0.5%, and the mass ratio of inulin to sodium alginate is 0.5:1;

[0126] Dissolve calcium chloride in deionized water to prepare a calcium chloride solution, wherein the mass percentage of calcium chloride in the calcium chloride solution is 1%;

[0127] According to the volume ratio of the aqueous solution containing inulin and sodium alginate to the calcium chloride solution of 4:1, under the stirring condition of a speed of 1000 r / min, the calcium chloride solution is added dropwise to the aqueous solution containing inulin and sodium alginate at a rate of 2 mL / min, after the dropwise addition is completed within 30 minutes, stirring is continued for 20 minutes, and an ultrasonic cell disruptor is used for disruption at a power of 200 W for 30 minutes. The cell is washed with deionized water and centrifuged three times, each centrifugation speed is 15000 r / min, and the time of each centrifugation is 10 minutes. The lower precipitate is collected and then freeze-dried to obtain composite nanogel particles;

[0128] The composite nano-gel particles are added into deionized water and stirred evenly to obtain an external aqueous phase; the mass percentage of the composite nano-gel particles in the external aqueous phase is 0.3%.

[0129] (4) The inner aqueous phase was added dropwise to the oil phase at a rate of 3 mL / min under stirring at a rotation speed of 500 r / min, with a mass ratio of the inner aqueous phase to the oil phase being 0.5:1. The mixture was sheared and homogenized at a rotation speed of 12,000 rpm at 45°C for 3 min to obtain a primary emulsion.

[0130] (5) The primary emulsion and the external aqueous phase are mixed by a microfluidic emulsification device. During the mixing process in the microfluidic emulsification device, the flow rate of the primary emulsion in the first branch channel 5 is 50 mL / h, and the flow rate of the internal and external aqueous phases in the second branch channel 6 is 50 mL / h by adjusting the first flow regulating valve 11 and the second flow regulating valve 12, thereby obtaining a double emulsion.

[0131] Examples 2 to 4 and Comparative Examples 1 to 3

[0132] The differences between Examples 2 to 4 and Comparative Examples 1 to 3 and Example 1 are:

[0133] In step (1) of Example 2, the components of the internal aqueous phase are as follows, calculated by mass percentage: 0.5% corn nanoparticles, 1% water-soluble active ingredient, 0.1% water-soluble arabinoxylan, and the balance deionized water;

[0134] In step (1) of Example 3, the components of the internal aqueous phase are as follows, calculated by mass percentage: 3% corn nanoparticles, 1% water-soluble active ingredient, 0.8% water-soluble arabinoxylan, and the balance deionized water;

[0135] In step (1) of Example 4, the components of the inner aqueous phase are as follows, calculated by mass percentage: 5% corn nanoparticles, 1% water-soluble active ingredient, 1% water-soluble arabinoxylan, and the balance deionized water.

[0136] In step (1) of Comparative Example 1, the components of the inner aqueous phase are as follows, calculated by mass percentage: 8% corn nanoparticles, 1% water-soluble active ingredient, 0.5% water-soluble arabinoxylan, and the balance deionized water.

[0137] In step (1) of Comparative Example 2, the components of the internal aqueous phase are as follows, calculated by mass percentage: 2% corn nanoparticles, 1% water-soluble active ingredient, and the balance deionized water.

[0138] In step (1) of Comparative Example 3, the components of the inner aqueous phase are as follows, calculated by mass percentage: 1% water-soluble active ingredient, 0.5% water-soluble arabinoxylan, and the balance deionized water.

[0139] Examples 5 to 9 and Comparative Examples 4 to 6

[0140] The differences between Examples 5 to 9 and Comparative Examples 4 to 6 and Example 1 are:

[0141] In step (3) of Example 5, the mass percentage of the composite nanogel particles is 0.05% based on the total mass of the external aqueous phase;

[0142] In step (3) of Example 6, the mass percentage of the composite nanogel particles is 0.1% based on the total mass of the external aqueous phase;

[0143] In step (3) of Example 7, the mass percentage of the composite nanogel particles is 0.5% based on the total mass of the external aqueous phase;

[0144] In step (3) of Example 8, the mass percentage of the composite nanogel particles is 1% based on the total mass of the external aqueous phase.

[0145] In step (3) of Example 9, the mass percentage of the composite nanogel particles is 2% based on the total mass of the external aqueous phase.

[0146] In step (3) of Comparative Example 4, the external aqueous phase is water, that is, no composite nanogel particles are added to the external aqueous phase.

[0147] In step (3) of Comparative Example 5, the mass percentage of the composite nanogel particles is 3% based on the total mass of the external aqueous phase.

[0148] In step (3) of Comparative Example 6, an equal amount of agarose was used to replace the inulin used in Example 1.

[0149] Examples 10 to 13 and Comparative Example 7

[0150] The differences between Examples 7 to 10 and Comparative Example 7 and Example 1 are:

[0151] In step (3) of Example 10, the mass ratio of inulin to sodium alginate is 0.1:1;

[0152] In step (3) of Example 11, the mass ratio of inulin to sodium alginate is 0.3:1;

[0153] In step (3) of Example 12, the mass ratio of inulin to sodium alginate is 0.8:1;

[0154] In step (3) of Example 13, the mass ratio of inulin to sodium alginate is 1:1;

[0155] In step (3) of Comparative Example 7, the mass ratio of inulin to sodium alginate is 2:1.

[0156] Examples 14 to 17

[0157] The differences between Examples 14 to 17 and Example 1 are:

[0158] In Example 14, the mass percentage of the beeswax in the oil phase is 0.5%;

[0159] In Example 15, the mass percentage of the beeswax in the oil phase is 1%;

[0160] In Example 16, the mass percentage of the beeswax in the oil phase is 3%;

[0161] In Example 17, the mass percentage of the beeswax in the oil phase is 5%.

[0162] Examples 18 to 21

[0163] The differences between Examples 18 to 21 and Example 1 are:

[0164] In Example 18, the volume ratio of the inner water phase to the oil phase is 0.1:1;

[0165] In Example 19, the volume ratio of the inner water phase to the oil phase is 0.3:1;

[0166] In Example 20, the volume ratio of the inner water phase to the oil phase is 0.8:1;

[0167] In Example 21, the volume ratio of the inner water phase to the oil phase is 1:1.

[0168] Examples 22 to 24

[0169] The differences between Examples 22 to 24 and Example 1 are:

[0170] In step (5) of Example 22, the flow rate of the primary emulsion in the first branch channel 5 is 50 mL / h, and the flow rate of the aqueous phase in and outside the second branch channel 6 is 25 mL / h;

[0171] In step (5) of Example 23, the flow rate of the primary emulsion in the first branch channel 5 is 50 mL / h, and the flow rate of the aqueous phase in and outside the second branch channel 6 is 75 mL / h;

[0172] In step (5) of Example 24, the flow rate of the primary emulsion in the first branch channel 5 is 50 mL / h, and the flow rate of the aqueous phase in and outside the second branch channel 6 is 100 mL / h.

[0173] Example 25

[0174] An embodiment of the highly stable double emulsion of the present invention, wherein the preparation method of the highly stable double emulsion is as follows:

[0175] (1) Preparation of internal aqueous phase

[0176] The corn was crushed and passed through a 300-mesh sieve to obtain corn powder; the corn powder was transferred to a grinder ( RESEARCH LAB), adding deionized water for ultrafine grinding for 2 h, the mass ratio of corn powder to deionized water is 1:5, filtering, sterilizing, and freeze-drying to obtain corn nanoparticles;

[0177] Prepare the following components of the internal aqueous phase in percentage by mass: 2% corn nanoparticles, 1% water-soluble active ingredient, 0.5% water-soluble arabinoxylan, and the balance deionized water; wherein the water-soluble active ingredient is ascorbic acid;

[0178] Dissolving water-soluble arabinoxylan in a portion of deionized water by stirring to prepare an arabinoxylan solution, wherein the mass percentage of arabinoxylan in the arabinoxylan solution is 5%;

[0179] dispersing the corn nanoparticles in the remaining deionized water to obtain a nanoparticle suspension; adding a water-soluble active ingredient to the nanoparticle suspension and mixing them uniformly to obtain a nanoparticle suspension loaded with the water-soluble active ingredient;

[0180] The arabinoxylan solution was added to the nanoparticle suspension loaded with the water-soluble active ingredient, and ultrasonically treated at a power of 200 W for 40 minutes to obtain an inner aqueous phase.

[0181] (2) Preparation of oil phase

[0182] Beeswax is dissolved in soybean oil, lutein is added, and stirred evenly to form an oil phase, wherein the mass percentage of the lutein in the oil phase is 1%, and the mass percentage of the beeswax in the oil phase is 5%.

[0183] (3) Preparation of external aqueous phase

[0184] Dissolving inulin and sodium alginate in water to obtain an aqueous solution containing inulin and sodium alginate, wherein the mass percentage of sodium alginate in the aqueous solution containing inulin and sodium alginate is 0.5%, and the mass ratio of inulin to sodium alginate is 0.5:1;

[0185] Dissolve calcium chloride in deionized water to prepare a calcium chloride solution, wherein the mass percentage of calcium chloride in the calcium chloride solution is 0.2%;

[0186] According to the volume ratio of the aqueous solution containing inulin and sodium alginate to the calcium chloride solution of 5:1, under the stirring condition of a speed of 700 r / min, the calcium chloride solution was dropwise added to the aqueous solution containing inulin and sodium alginate at a rate of 1 mL / min, after the dropwise addition was completed within 60 minutes, stirring was continued for 10 minutes, and the cell was disrupted using an ultrasonic cell disruptor at a power of 200 W for 30 minutes, washed with deionized water and centrifuged three times, each centrifugation speed was 15000 r / min, and the time of each centrifugation was 10 minutes. The lower precipitate was collected and then freeze-dried to obtain composite nanogel particles;

[0187] The composite nano-gel particles are added into deionized water and stirred evenly to obtain an external aqueous phase; the mass percentage of the composite nano-gel particles in the external aqueous phase is 2%.

[0188] (4) The inner aqueous phase was added dropwise to the oil phase at a rate of 1 mL / min under stirring at a rotation speed of 500 r / min, with a mass ratio of the inner aqueous phase to the oil phase being 0.1:1. The mixture was sheared and homogenized at a rotation speed of 10,000 rpm at 40°C for 4 min to obtain a primary emulsion.

[0189] (5) The primary emulsion and the external aqueous phase are mixed by a microfluidic emulsification device. During the mixing process of the microfluidic emulsification device, the primary emulsion at a flow rate of 50 mL / h and the external aqueous phase at a flow rate of 100 mL / h are merged by adjusting the first flow regulating valve 11 and the second flow regulating valve 12 to obtain a double emulsion.

[0190] Example 26

[0191] An embodiment of the highly stable double emulsion of the present invention, wherein the preparation method of the highly stable double emulsion is as follows:

[0192] (1) Preparation of internal aqueous phase

[0193] The corn was crushed and passed through a 300-mesh sieve to obtain corn powder; the corn powder was transferred to a grinder ( RESEARCH LAB), adding deionized water for ultrafine grinding for 1 h, the mass ratio of corn powder to deionized water is 1:20, filtering, sterilizing, and freeze-drying to obtain corn nanoparticles;

[0194] Prepare the following components of the internal aqueous phase in percentage by mass: 2% corn nanoparticles, 1% water-soluble active ingredient, 0.5% water-soluble arabinoxylan, and the balance deionized water; wherein the water-soluble active ingredient is ascorbic acid;

[0195] Dissolving water-soluble arabinoxylan in a portion of deionized water by stirring to prepare an arabinoxylan solution, wherein the mass percentage of arabinoxylan in the arabinoxylan solution is 5%;

[0196] dispersing the corn nanoparticles in the remaining deionized water to obtain a nanoparticle suspension; adding a water-soluble active ingredient to the nanoparticle suspension and mixing them uniformly to obtain a nanoparticle suspension loaded with the water-soluble active ingredient;

[0197] The arabinoxylan solution was added to the nanoparticle suspension loaded with the water-soluble active ingredient, and ultrasonically treated at a power of 500 W for 20 minutes to obtain an inner aqueous phase.

[0198] (2) Preparation of oil phase

[0199] Beeswax is dissolved in soybean oil, lutein is added, and stirred evenly to form an oil phase, wherein the mass percentage of the lutein in the oil phase is 1%, and the mass percentage of the beeswax in the oil phase is 5%.

[0200] (3) Preparation of external aqueous phase

[0201] Dissolving inulin and sodium alginate in water to obtain an aqueous solution containing inulin and sodium alginate, wherein the mass percentage of the sodium alginate in the aqueous solution containing inulin and sodium alginate is 1%, and the mass ratio of the inulin to the sodium alginate is 0.5:1;

[0202] Dissolve calcium chloride in deionized water to prepare a calcium chloride solution, wherein the mass percentage of calcium chloride in the calcium chloride solution is 2%;

[0203] According to the volume ratio of the aqueous solution containing inulin and sodium alginate to the calcium chloride solution of 3:1, under the stirring condition of a speed of 1200 r / min, the calcium chloride solution is added dropwise to the aqueous solution containing inulin and sodium alginate at a rate of 3 mL / min, after the dropwise addition is completed within 20 minutes, stirring is continued for 30 minutes, and then an ultrasonic cell disruptor is used for 10 minutes at a power of 300 W. The cell is washed with deionized water and centrifuged three times, each centrifugation speed is 15000 r / min, and the time of each centrifugation is 10 minutes. The lower precipitate is collected and then freeze-dried to obtain composite nanogel particles;

[0204] The composite nano-gel particles are added into deionized water and stirred evenly to obtain an external aqueous phase; the mass percentage of the composite nano-gel particles in the external aqueous phase is 2%.

[0205] (4) The inner aqueous phase was added dropwise to the oil phase at a rate of 5 mL / min under stirring at a rotation speed of 500 r / min, with a mass ratio of the inner aqueous phase to the oil phase being 1:1. The mixture was sheared and homogenized at a rotation speed of 15,000 rpm at 45°C for 2 min to obtain a primary emulsion.

[0206] (5) The primary emulsion and the external aqueous phase are mixed by a microfluidic emulsification device. During the mixing process of the microfluidic emulsification device, the primary emulsion at a flow rate of 50 mL / h and the external aqueous phase at a flow rate of 100 mL / h are merged by adjusting the first flow regulating valve 11 and the second flow regulating valve 12 to obtain a double emulsion.

[0207] In order to verify the performance of the double emulsions of the present invention, the double emulsions prepared in the examples and comparative examples were used as samples to perform the following performance tests. The specific steps are as follows:

[0208] (1) The average particle size (i.e., initial particle size) of each sample was measured using a Malvern laser particle size analyzer within 24 hours of preparation. The results are shown in Table 1.

[0209] (2) Each sample was placed in a transparent glass bottle, sealed, and stored at 25°C for 15 days. During the storage process, the samples were regularly observed to see if there was any stratification or oil or water separation. The observation results were statistically analyzed. "Unstable" indicated that there was any stratification or oil or water separation, and "stable" indicated that there was no stratification or oil or water separation.

[0210] For samples that did not experience stratification or oil or water separation after storage, the average particle size was measured using a Malvern laser particle size analyzer, and the particle size change rate was calculated according to the following formula:

[0211] Particle size change rate (%) = (average particle size of the sample after storage - initial particle size of the sample) / initial particle size of the sample * 100%.

[0212] (3) Each sample was placed in a transparent glass bottle, sealed, and placed at a low temperature of -5±2°C for 18 hours, and then at room temperature (25°C) for 6 hours. After repeated placement at low temperature and room temperature three times, the transparent glass bottle was opened and stirred with a glass rod to observe whether the sample showed any stratification or oil or water separation. The observation results were counted, and "unstable" indicated that stratification or oil or water separation occurred, and "stable" indicated that no stratification or oil or water separation occurred.

[0213] The test results are shown in Table 1.

[0214] Table 1

[0215]

[0216]

[0217] As can be seen from Table 1, the double emulsion prepared in the embodiment of the present invention has good storage stability and can be stably stored in both low temperature and room temperature environments.

[0218] It can be seen from Examples 1 to 4 and Comparative Examples 1 to 3 that introducing an appropriate amount of corn nanoparticles and arabinoxylan into the inner aqueous phase can synergistically reduce interfacial tension, reduce the initial particle size of the double emulsion, and improve the storage stability and freeze-thaw stability of the double emulsion.

[0219] From Example 1, Examples 5-9, and Comparative Examples 4-5, it can be seen that when the mass percentage of the composite nanogel particles in the external aqueous phase is 0-2%, as the mass percentage of the composite nanogel particles increases, more composite nanogel particles are adsorbed on the oil-water interface, the interfacial film formed becomes denser, the initial particle size of the droplets is reduced, and at the same time, the droplet coalescence and maturation can be more effectively inhibited, the stability of the double emulsion is better, and the change in the droplet size during storage is smaller. The amount of composite nanogel particles added to the external aqueous phase of Examples 1 and Examples 6-7 is appropriate, the composite nanogel particles fully cover the oil-water interface, and form a dense barrier, which reduces the initial particle size of the droplets, effectively inhibits the droplet swelling, aggregation, and maturation, and reduces the change in the droplet size during storage. However, if the mass percentage of the composite nanogel particles in the external aqueous phase is increased too much, a large number of free composite nanogel particles will be present in the external aqueous phase, which will easily settle during storage and centrifugation, destroying the homogeneity of the double emulsion and causing stratification.

[0220] Compared with Comparative Examples 6 to 7, the addition amount of inulin relative to sodium alginate in Examples 1 and 10 to 13 of the present invention is appropriate, which can effectively improve the storage stability and freeze-thaw stability of the double emulsion.

[0221] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A highly stable double emulsion, characterized in that: It includes an inner water phase, an oil phase and an outer water phase, wherein: The inner aqueous phase comprises a water-soluble active ingredient, cereal nanoparticles, arabinoxylan and water. Based on the total mass of the inner aqueous phase, the mass percentage of the cereal nanoparticles is 0.5-5%, and the mass percentage of the arabinoxylan is 0.1-1%. The oil phase includes an oil-soluble active ingredient and liquid oil, and the oil-soluble active ingredient includes lutein; The external aqueous phase includes water.

2. The highly stable double emulsion according to claim 1, wherein The volume ratio of the inner water phase to the oil phase is (0.1-1):1; And / or, the ratio between the volume of the external aqueous phase and the total volume of the internal aqueous phase and the oil phase is (1-5):

1.

3. The highly stable double emulsion according to claim 1, wherein The cereal nanoparticles include at least one of corn nanoparticles, wheat nanoparticles, and rice nanoparticles; And / or, the cereal nanoparticles are prepared by the following method: crushing cereals, adding water for grinding, filtering, sterilizing, and freeze-drying to obtain cereal nanoparticles.

4. The highly stable double emulsion according to claim 1, wherein The internal aqueous phase is prepared by the following method: A1. Dispersing the cereal nanoparticles in water to prepare a nanoparticle suspension; A2. adding a water-soluble active ingredient to the nanoparticle suspension and mixing to obtain a nanoparticle suspension loaded with the water-soluble active ingredient; A3. Dissolve arabinoxylan in water to prepare an arabinoxylan solution, mix the nanoparticle suspension loaded with water-soluble active ingredients and the arabinoxylan solution, and perform ultrasonic treatment to obtain an inner aqueous phase.

5. The highly stable double emulsion according to claim 1, wherein The external aqueous phase also includes composite nanogel particles, which are prepared by the following method: dropping a calcium chloride solution into an aqueous solution containing inulin and sodium alginate, stirring, crushing, filtering, and drying to obtain composite nanogel particles; Based on the total mass of the external aqueous phase, the mass percentage of the composite nano-gel particles is 0.05-2%.

6. The highly stable double emulsion according to claim 1, wherein The oil phase further comprises natural wax, wherein the mass percentage of the natural wax in the oil phase is 1 to 10%, and the natural wax comprises at least one of beeswax, palm wax, rice bran wax, and soybean wax; And / or, the liquid oil includes at least one of soybean oil, rapeseed oil, peanut oil, cottonseed oil, sunflower oil, sesame oil, camellia oil, linseed oil, corn oil, rice bran oil, olive oil, coconut oil, and palm oil.

7. A method for preparing a highly stable double emulsion, characterized in that: The steps include: S1. Add the inner aqueous phase dropwise into the oil phase under stirring, shear and homogenize to obtain a primary emulsion; S2. The primary emulsion obtained in step S2 and the external aqueous phase are mixed through a microfluidic emulsification device to obtain a double emulsion.

8. The method for preparing a highly stable double emulsion according to claim 7, wherein: In step S1, the shearing temperature is 40-65° C., the rotation speed is 10000-15000 rpm, and the time is 2-4 minutes.

9. The method for preparing a highly stable double emulsion according to claim 7, wherein: In the microfluidic emulsification device of step S2, the ratio between the flow rate of the primary emulsion and the total flow rate of the external aqueous phase is 1:(1-5).

10. Use of the highly stable double emulsion according to any one of claims 1 to 6 in preparing food.

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