A water-in-oil microemulsion DHA algal oil, its preparation method and application

Abstract

This invention relates to DHA algal oil preparation technology, specifically to a water-in-oil microemulsion DHA algal oil, its preparation method, and its application. The method includes the following steps: mixing walnut oil, medium-chain triglycerides, vitamin E, and phospholipids, and heating in a water bath to obtain an oil phase; dissolving DHA algal oil, γ-aminobutyric acid, steviol glycosides, sodium caseinate, xanthan gum, Alpinia oxyphylla, hawthorn, yam, Codonopsis pilosula, bovine spleen peptide, phospholipids, and chicken gizzard lining in purified water and dispersing to obtain an aqueous phase; adding the oil phase to the aqueous phase to form a crude emulsion, and homogenizing to obtain an encapsulated emulsion. Compared with existing technologies, this invention solves the problems of poor stability, poor oxidation resistance, and a noticeable fishy odor in DHA algal oil beverages. The DHA algal oil beverage prepared by this method exhibits excellent thermal stability and freeze-thaw stability; it shows significant tolerance to chemical factors such as acids, alkalis, and salts; and it possesses excellent long-term storage stability.

Description

Technical Field

[0001] This invention relates to DHA algal oil preparation technology, specifically to an oil-in-water microemulsion DHA algal oil, its preparation method, and its application. Background Technology

[0002] DHA algal oil beverages are rich in docosahexaenoic acid (DHA), an important ω3 long-chain polyunsaturated fatty acid that plays a key role in promoting the development of neuronal synapses and the maturation of retinal photoreceptors in infants and young children. It also plays an important physiological role in regulating blood lipids, maintaining the function of cardiovascular endothelial cells, and reducing the risk of atherosclerosis. Currently, the industrialization process of DHA algal oil microemulsion beverages faces the following challenges and problems: (1) Algal oil stability problem: DHA algal oil is easily affected by light, oxygen, and temperature, resulting in oxidative rancidity, which leads to flavor deterioration and loss of nutritional activity. It is necessary to optimize the antioxidant system or develop new encapsulation technology. (2) Sensory quality optimization needs: The fishy smell or special odor of algal oil itself may affect the palatability of the beverage. It is necessary to improve the taste through additional deodorization technology or flavor masking technology.

[0003] Currently, the industrialization technology for DHA algal oil mainly includes microjet technology. This technology uses high pressure to force fluid through tiny channels or nozzles, generating a high-speed jet. This causes the material to undergo intense shearing, collision, and cavitation instantaneously, forming stable liposomes or emulsion systems. However, traditional microjet devices suffer from problems such as complex operation, high cost, and difficulty in continuous production.

[0004] In the prior art, CN119257249A discloses a DHA algal oil oral liquid and its preparation method. The preparation method of the present invention includes the following steps: sodium hexametaphosphate, disodium hydrogen phosphate, sodium caseinate, sodium octenyl succinate starch and water are mixed and refrigerated to obtain an aqueous phase; docosahexaenoic acid, caprylic / capric triglyceride, fragrance and vitamin E oil are mixed to obtain an oil phase; the oil phase is added to the aqueous phase and stirred at high speed, and the primary emulsion is homogenized to obtain an encapsulated emulsion; the encapsulated emulsion, sucralose, sweet orange fragrance and water are mixed to obtain a DHA algal oil oral liquid. However, this preparation method has some shortcomings, such as: (1) poor stability: relying only on a single emulsifier, the interfacial film strength is insufficient, and it is easy to separate and precipitate during long-term storage. (2) weak antioxidant capacity: relying only on vitamin E as a single antioxidant, it cannot effectively inhibit the oxidative rancidity of DHA, which easily produces a rancid odor and has a short shelf life. (3) Sensory quality depends on artificial additives: The use of flavorings and sucralose to adjust the taste does not conform to the trend of clean labeling and lacks natural flavor components. (4) Complex process and high energy consumption: The aqueous phase needs to be refrigerated and pretreated, which increases the production process and energy consumption and is not conducive to continuous production. (5) High cost: The use of a variety of special emulsifiers and additives results in high raw material costs.

[0005] Therefore, it is of great significance to study and prepare a DHA algal oil oral liquid that has improved stability, oxidation resistance, good sensory quality, simple operation process, low cost, and can achieve continuous production. Summary of the Invention

[0006] The purpose of this invention is to address at least one of the aforementioned problems by providing a water-in-oil microemulsion DHA algal oil, its preparation method, and its application. This addresses the issues of poor stability, poor oxidation resistance, and a noticeable fishy odor in existing DHA algal oil beverages. The DHA algal oil beverage prepared using this method employs a double-layer nanoemulsion structure, exhibiting excellent thermal and freeze-thaw stability, maintaining system stability even under drastic temperature changes. It demonstrates significant tolerance to chemical factors such as acids, alkalis, and salts, adapting to various complex processing scenarios. Furthermore, it possesses excellent long-term storage stability, effectively extending the product's shelf life.

[0007] The objective of this invention is achieved through the following technical solution: The first aspect of this invention discloses a method for preparing water-in-oil microemulsion DHA algal oil, comprising the following steps: S1: Mix walnut oil, medium-chain triglycerides, vitamin E, and phospholipids, and stir until completely dissolved under water bath heating to obtain the oil phase; S2: Dissolve DHA algal oil, γ-aminobutyric acid, steviol glycosides, sodium caseinate, xanthan gum, Alpinia oxyphylla, hawthorn, yam, Codonopsis pilosula, bovine spleen peptide, phospholipids and chicken gizzard membrane in purified water, stir and disperse evenly to obtain an aqueous phase; S3: The aqueous phase obtained in step S2 is stirred at low speed and the oil phase obtained in step S1 is added to the aqueous phase. The mixture is stirred at high speed to form a crude emulsion. The crude emulsion is homogenized to obtain an encapsulated emulsion. The encapsulation emulsion is an oil-in-water microemulsion of DHA algal oil.

[0008] Preferably, in step S1: The mass ratio of walnut oil, medium-chain triglycerides, vitamin E, and phospholipids is (1~2):(0.1~1):(0.01~0.09):(0.1~0.9).

[0009] Preferably, in step S1: The water bath heating temperature is 55~65 ℃, and the water bath heating time is 2.5~3.5 h; The stirring rate is 450~550 r / min.

[0010] Preferably, in step S2: The mass ratio of DHA algal oil, γ-aminobutyric acid, steviol glycosides, sodium caseinate, xanthan gum, Alpinia oxyphylla, hawthorn, yam, Codonopsis pilosula, bovine spleen peptide, phospholipids, chicken gizzard lining and water is (3~4):(0.1~0.9):(0.01~0.1):(0.1~1):(0.1~1):(0.1~1):(0.1~1):(0.1~1):(0.1~1):(0.1~1):(0.1~1):(0.1~0.5):(0.1~1):(50~100).

[0011] Preferably, in step S2: The stirring and dispersion temperature is 45~55 ℃, the stirring and dispersion time is 10~20 min, and the stirring and dispersion rate is 450~550 r / min.

[0012] Preferably, in step S3: The low-speed stirring rate is 5000~8000 r / min; The high-speed stirring rate is 8000~12000 r / min, and the high-speed stirring time is 5~10 min.

[0013] Preferably, in step S3: The homogenization is performed 2 to 4 times, and the homogenization pressure is 50 to 80 MPa.

[0014] Preferably, in step S3: The mass ratio of the oil phase to the water phase is 1:(6~15).

[0015] The second aspect of this invention discloses an oil-in-water microemulsion DHA algal oil, which is prepared using any of the preparation methods described above; The water-in-oil microemulsion DHA algal oil described herein has a double-layer nanoemulsion structure.

[0016] The third aspect of this invention discloses the application of the above-described water-in-oil microemulsion DHA algal oil in the preparation of DHA algal oil nanoemulsion oral liquid, further comprising step S4: S4: Mix the encapsulation emulsion obtained in step S3 with sweet orange oil flavoring and water to obtain DHA algal oil nanoemulsion oral liquid; in, The mass ratio of the encapsulating emulsion, sweet orange oil flavoring, and water is (20~46):(0.05~0.2):(53~79).

[0017] The working principle of this invention is as follows: This invention constructs a stable oil-in-water microemulsion system through a synergistic mechanism of "interface engineering + rheological regulation + multiple antioxidants": (1) Emulsion formation: The oil phase (DHA algal oil, walnut oil, etc.) in the aqueous phase is broken into submicron-sized oil droplets by high-speed shearing and homogenization, forming a thermodynamically stable microemulsion. (2) Interface stability: Phospholipids (small molecule emulsifiers) and sodium caseinate (large molecule emulsifiers) are synergistically adsorbed at the oil-water interface. Phospholipids fill the gaps between protein molecules, forming a high-strength composite interface film. (3) Fluid locking: Xanthan gum increases phase viscosity, physically locking the movement of oil droplets and inhibiting sedimentation. (4) Antioxidant protection: Vitamin E, polyphenols and the barrier effect of the interface film constitute a dual protection of chemical scavenging and physical oxygen barrier.

[0018] Compared with the prior art, the present invention has the following beneficial effects: 1) This invention utilizes oil-in-water microemulsion technology to successfully prepare DHA algal oil beverages, meeting market demand for high-quality DHA algal oil. The DHA algal oil beverage of this invention forms a double-layer nanoemulsion structure, greatly improving emulsion stability. Even under extreme conditions such as high acidity / alkali, high salt, heating, and freeze-thaw cycles, the emulsion maintains its physicochemical stability, effectively solving the problem of instability in traditional DHA algal oil during storage and processing, and providing the market with a new choice of high-quality, high-stability DHA products. The DHA algal oil nanoemulsion oral liquid prepared by the method of this invention has good thermal stability, enabling long-term storage, and provides a technical reference for the development of high-stability DHA algal oil products and their application in food processing.

[0019] 2) Uniform particle size distribution: This invention prepares a nanoscale emulsion system with uniform particle size by precisely controlling the ratio of the aqueous and oil phases and combining it with a high-pressure homogenization process. This refined particle size control effectively improves the physical stability of the emulsion, reduces the risk of stratification and flocculation, and significantly enhances its bioavailability, providing technical support for achieving efficient absorption and utilization of DHA.

[0020] 3) Oxidation protection: The structure of the double-layer nanoemulsion of the present invention provides an additional protective layer for DHA, reducing the possibility of oxidation and effectively extending the shelf life of the product.

[0021] 4) Masking unpleasant flavors: The fishy or special odor of DHA algal oil itself may affect the palatability of beverages. Through emulsification, these unpleasant flavors can be effectively masked, improving the sensory quality of the product. Attached Figure Description

[0022] Figure 1 The particle size distribution of the DHA algal oil nanoemulsion oral liquid in Example 1 is shown. Detailed Implementation

[0023] Unless otherwise specified, the reagents used in the following description may be commercially available products, the methods used may be those known in the art, and any other matters not covered herein may be handled using existing technology.

[0024] This solution provides a method for preparing DHA algal oil beverages, including the following steps: 1) Mix walnut oil, medium-chain triglycerides, vitamin E, and phospholipids, heat in a water bath and stir until completely dissolved, keep warm for later use, and obtain the oil phase; 2) Dissolve DHA algal oil, γ-aminobutyric acid, steviol glycosides, sodium caseinate, xanthan gum, Alpinia oxyphylla, hawthorn, yam, Codonopsis pilosula, bovine spleen peptide, phospholipids, and chicken gizzard membrane in an appropriate amount of purified water and stir until completely dispersed to obtain an aqueous phase; 3) While stirring the aqueous phase, slowly pour the oil phase into the aqueous phase and stir at high speed to form a crude emulsion; homogenize the crude emulsion to obtain an encapsulated emulsion (water-in-oil microemulsion DHA algal oil, which is a double-layer nanoemulsion structure). 4) Mix the encapsulated emulsion, sweet orange oil flavoring, and water to obtain a DHA algal oil beverage.

[0025] In this invention, in step 1), the mass ratio of walnut oil, medium-chain triglycerides, vitamin E, and phospholipids is (1~2):(0.1~1):(0.01~0.09):(0.1~0.9).

[0026] A further preferred ratio is (1~1.5):(0.1~0.5):(0.01~0.05):(0.1~0.7).

[0027] More preferably, (1~1.3):(0.1~0.3):(0.01~0.03):(0.1~0.4).

[0028] In this invention, in step 1), the mixing temperature is preferably 55~65 ℃, more preferably 57~62 ℃, and even more preferably 60 ℃; the mixing time is preferably 2.5~3.5 h, and even more preferably 3 h; stirring is preferably carried out during the mixing process, and the stirring rate is preferably 450~550 r / min, more preferably 480~520 r / min, and even more preferably 500 r / min.

[0029] In this invention, in step 2), the mass ratio of DHA algal oil, γ-aminobutyric acid, steviol glycoside, sodium caseinate, xanthan gum, Alpinia oxyphylla, hawthorn, yam, Codonopsis pilosula, bovine spleen peptide, phospholipids, chicken gizzard lining and water is (3~4):(0.1~0.9):(0.01~0.1):(0.1~1):(0.1~1):(0.1~1):(0.1~1):(0.1~1):(0.1~1):(0.1~1):(0.1~1):(0.1~1):(0.1~0.5):(0.1~1):(50~100).

[0030] Further preferred is (3.5~4):(0.3~0.9):(0.01~0.07):(0.1~0.7):(0.1~0.7):(0.1~0.7):(0.1~0.7):(0.1~0.7):(0.1~0.7):(0.1~0.7):(0.1~0.5):(0.1~0.7):(60~100).

[0031] More preferably, (3.7~4):(0.5~0.7):(0.01~0.05):(0.1~0.5):(0.5~1):(0.1~0.5):(0.1~0.5):(0.1~0.5):(0.1~0.5):(0.1~0.5):(0.1~0.5):(0.1~0.5):(80~100).

[0032] In this invention, in step 2), the mixing temperature is 45~55 ℃, more preferably 47~52 ℃, and even more preferably 50 ℃; the mixing time is preferably 10~20 min, more preferably 12~18 min, and even more preferably 14~15 min; stirring is preferably carried out during the mixing process, and the stirring rate is preferably 450~550 r / min, more preferably 480~520 r / min, and even more preferably 500 r / min.

[0033] In this invention, during step 3), the stirring rate of the aqueous phase during the addition of the oil phase to the aqueous phase is preferably 5000~8000 r / min, more preferably 5500~7500 r / min, and even more preferably 6000~7000 r / min. The high-speed stirring rate after the oil phase is added is preferably 8000~12000 r / min, more preferably 9000~11000 r / min, and even more preferably 10000 r / min. The high-speed stirring time is preferably 5~10 min, more preferably 6~9 min, and even more preferably 7~8 min.

[0034] In this invention, in step 3), the number of homogenizations is preferably 2 to 4 times, more preferably 3 times, and the homogenization pressure is preferably 50 to 80 MPa, more preferably 55 to 75 MPa, and even more preferably 60 to 70 MPa.

[0035] In this invention, in step 3), the mass ratio of the oil phase to the water phase is preferably 1:(6~15), more preferably 1:(8~13), and even more preferably 1:(10~11).

[0036] In this invention, in step 4), the preferred mass ratio of the encapsulating emulsion, sweet orange oil flavoring, and water is (20~46):(0.05~0.2):(53~79).

[0037] In this invention, after mixing in step 4), the mixture is sequentially stirred, circulated, and filtered to obtain a DHA algal oil beverage. The stirring rate is preferably 40-60 r / min, more preferably 45-55 r / min, and even more preferably 50 r / min. The stirring time is preferably 25-35 min, more preferably 28-32 min, and even more preferably 30 min. The pressure for circulating the liquid is preferably 0.1-0.6 MPa, more preferably 0.2-0.5 MPa, and even more preferably 0.3-0.4 MPa.

[0038] The DHA algal oil beverage prepared based on the above preparation method is a DHA algal oil nanoemulsion oral liquid.

[0039] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0040] It should be noted that the quantities mentioned in the examples are all by weight.

[0041] Example 1 Add 1 part walnut oil to a shear emulsification tank, along with 0.3 parts medium-chain triglycerides, 0.03 parts vitamin E, 0.001 parts oil-soluble flavoring, and 0.1 parts phospholipids. Heat to 60 °C and stir at 500 r / min for 3 h to obtain a homogeneous oil phase.

[0042] Place 25 parts purified water in a stainless steel container, add 3.75 parts DHA algal oil, 0.5 parts γ-aminobutyric acid, 0.01 parts steviol glycosides, 0.5 parts sodium caseinate, and 1 part xanthan gum. Stir at 500 r / min for 15 min until completely dispersed. Add 0.5 parts Alpinia oxyphylla, 0.5 parts hawthorn, 0.5 parts Dioscorea opposita, 0.5 parts Codonopsis pilosula, and 0.5 parts chicken gizzard extract, and stir evenly. Add 0.5 parts bovine spleen peptide and 0.1 parts phospholipids to obtain a homogeneous aqueous phase.

[0043] The oil phase was slowly added to the aqueous phase under stirring (stirring speed of 7000 r / min) at a mass ratio of 1:10. The mixture was then stirred at a high speed of 10000 r / min for 8 min to obtain the primary emulsion. The primary emulsion was then homogenized in a high-pressure homogenizer (the entire primary emulsion passed through the homogenization pipe once, and a total of 3 homogenizations were performed) at a pressure of 70 MPa to obtain the encapsulated emulsion.

[0044] Add the encapsulation emulsion, sweet orange oil flavoring, and purified water (mass ratio of encapsulation emulsion, sweet orange flavoring, and water is 40:0.1:70) to a 100 mL mixing tank and bring the volume to a final volume to obtain a solution. Turn on the stirrer and the drug solution circulation pump (stirring rate 50 r / min, stirring time 30 min, drug solution circulation pump pressure 0.35 MPa), filter the solution through a 300-mesh stainless steel filter to obtain DHA algal oil nanoemulsion oral solution.

[0045] Example 2 Add 1.5 parts of walnut oil to a shear emulsification tank, along with 0.5 parts of medium-chain triglycerides, 0.05 parts of vitamin E, 0.001 parts of oil-soluble flavoring, and 0.5 parts of phospholipids. Heat to 55 °C and stir at 550 r / min for 3.5 h to obtain a homogeneous oil phase.

[0046] Place 50 parts of purified water in a stainless steel container, add 3.5 parts of DHA algal oil, 0.6 parts of γ-aminobutyric acid, 0.05 parts of steviol glycosides, 0.7 parts of sodium caseinate, and 0.6 parts of xanthan gum. Stir at 550 r / min for 18 min until completely dispersed. Add 1 part of Alpinia oxyphylla, 1 part of hawthorn, 1 part of yam, 1 part of Codonopsis pilosula, and 1 part of chicken gizzard extract, and stir well. Add 1 part of bovine spleen peptide and 0.2 parts of phospholipids to obtain a homogeneous aqueous phase.

[0047] The oil phase was slowly added to the aqueous phase under stirring (stirring speed of 8000 r / min) at a mass ratio of 1:10. The mixture was then stirred at a high speed of 10000 r / min for 5 min to obtain the primary emulsion. The primary emulsion was then homogenized in a high-pressure homogenizer (the primary emulsion was completely passed through the homogenization pipe once, and homogenization was performed 3 times in total) at a pressure of 60 MPa to obtain the encapsulated emulsion.

[0048] Add the encapsulation emulsion, sweet orange oil flavoring, and purified water (mass ratio of encapsulation emulsion, sweet orange flavoring, and water is 40:0.1:70) to a 100 mL mixing tank and bring the volume to a final volume to obtain a solution. Turn on the stirrer and the drug solution circulation pump (stirring rate 50 r / min, stirring time 30 min, drug solution circulation pump pressure 0.35 MPa), filter the solution through a 300-mesh stainless steel filter to obtain DHA algal oil nanoemulsion oral solution.

[0049] The particle size distribution of the DHA algal oil nanoemulsion beverage in Example 1 is as follows: Figure 1 As shown, from Figure 1 As can be seen, the DHA algal oil nanoemulsion oral liquid has a small particle size and narrow particle size distribution, with a particle size distribution range of 100~150 nm and an average particle size of 132 nm.

[0050] The water solubility and stability of the DHA algal oil nanoemulsion oral liquid beverages prepared in Examples 1 and 2 were tested. The testing portion of this invention (including methods and conditions) is referenced from Chinese Patent CN119257249A.

[0051] (1) Results of water solubility test: The DHA algal oil nanoemulsion beverages in Examples 1 and 2 can dissolve rapidly in water, and the solution becomes clear, indicating that the DHA algal oil nanoemulsion beverages have good water solubility.

[0052] (2) Stability test: 1) Centrifugation experiment: Take 30 mL of the algal oil DHA nanoemulsion beverage from Example 1 and place it in a centrifuge tube for centrifugation.

[0053] Evaluation criteria: No stratification should be observed after centrifugation at 4000 r / min for 15 min.

[0054] The test results show that the DHA algal oil nanoemulsion beverage prepared in Example 1 did not exhibit stratification and its stability met the requirements.

[0055] 2) Temperature stability test: The DHA algal oil nanoemulsion beverage from Example 1 was filled into a soda-lime glass bottle and sealed. It was placed at 30 ℃, 50 ℃, and 70 ℃ for 10 days, respectively. The particle size of the DHA algal oil nanoemulsion beverage (DHA algal oil nanoemulsion oral liquid) was tested at 0 days, 5 days, and 10 days, respectively. The results are shown in Table 1.

[0056] Table 1 Temperature stability test results of Example 1 As shown in Table 1, the particle size of the DHA algal oil nanoemulsion beverage (DHA algal oil nanoemulsion) did not change significantly at different temperatures, indicating good temperature stability. However, since the DHA algal oil in it is a fat-soluble component, it should not be stored for too long under high temperature conditions.

[0057] 3) Accelerated testing: The accelerated test was conducted at 30 °C. The DHA algal oil nanoemulsion beverage of Example 1 was placed at 30 °C for 1 month, and the physical properties of the DHA algal oil nanoemulsion beverage were investigated at 10 days, 20 days and 30 days. The results are shown in Table 2.

[0058] Table 2. Accelerated test results of Example 1 As shown in Table 2, under accelerated testing conditions, the particle size of the DHA algal oil nanoemulsion beverage did not change significantly.

[0059] Comparative Example 1 Add 25 parts of purified water to a shear emulsifying tank, then add 0.05 parts of sodium hexametaphosphate, 0.005 parts of disodium hydrogen phosphate, 0.5 parts of sodium caseinate, and 0.3 parts of sodium octenyl succinate starch. Heat to 50°C and stir at 500 r / min for 3 h. Then refrigerate at 6°C for 12 h to obtain a homogeneous aqueous phase.

[0060] Place 3 parts of docosahexaenoic acid in a stainless steel container, add 0.5 parts of caprylic / capric triglyceride, 0.3 parts of sweet orange oil flavoring, and 0.02 parts of vitamin E oil, and stir at 500 r / min for 15 min to obtain a homogeneous oil phase.

[0061] The oil phase was slowly added to the aqueous phase under stirring (stirring speed of 7000 r / min) at a mass ratio of 1:10. The mixture was then stirred at a high speed of 10000 r / min for 8 min to obtain the primary emulsion. The primary emulsion was then homogenized in a high-pressure homogenizer (the entire primary emulsion passed through the homogenization pipe once, and a total of 3 homogenizations were performed) at a pressure of 70 MPa to obtain the encapsulated emulsion.

[0062] Add the encapsulation emulsion to a 100 mL mixing vessel, then add sweet orange oil flavoring and purified water (mass ratio of encapsulation emulsion, sweet orange flavoring, and water is 40:0.1:70) and bring the volume to a final volume to obtain a solution. Turn on the stirrer and the drug solution circulation pump (stirring rate 50 r / min, stirring time 30 min, drug solution circulation pump pressure 0.3 MPa), and filter the solution through a 300-mesh stainless steel filter to obtain DHA algal oil nanoemulsion oral solution.

[0063] A performance comparison analysis was conducted between the present invention (taking Example 1 as an example) and Comparative Example 1: 1. Differences in emulsion structure stability Comparative Example 1, using only a single-layer emulsifier, could only form a single-layer interfacial film, resulting in weak interfacial strength and a tendency for stratification or flocculation during long-term storage. In contrast, the present invention employs synergistic adsorption of phospholipids and sodium caseinate to form a bilayer nanoemulsion structure, resulting in a denser interfacial film and significantly improving the emulsion's anti-aggregation ability and storage stability. Furthermore, accelerated testing (30°C, 30 days) verified that the particle size of the present invention did not change significantly; while Comparative Example 1 easily experienced particle size increase or stratification under the same conditions.

[0064] 2. Differences in antioxidant capacity The formulation in Comparative Example 1 relies solely on Vitamin E as an antioxidant, representing a single chemical antioxidant mechanism, which is insufficient to effectively inhibit the oxidative rancidity of DHA during long-term storage. In contrast, the present invention employs a dual protection mechanism of "chemical scavenging + physical oxygen barrier": Vitamin E and polyphenols from natural extracts such as Alpinia oxyphylla and hawthorn synergistically scavenge free radicals, while the resulting double-layered interfacial film further effectively blocks oxygen from contacting oil droplets, significantly slowing down the oxidation process and ultimately extending shelf life.

[0065] 3. Differences in sensory quality and adaptability to cleaning labels The formulation in Comparative Example 1 uses sucralose and flavorings to adjust the taste, relying heavily on artificial additives, which does not align with current clean label trends. In contrast, the formulation of this invention utilizes natural ingredients such as γ-aminobutyric acid (GABA), steviol glycosides, Alpinia oxyphylla, hawthorn, and yam, which combine masking of fishy odors, flavoring, and nutritional fortification, achieving optimized taste from natural sources and better meeting consumer demand for natural and healthy products.

[0066] 4. Process complexity and cost differences The oral liquid prepared in Comparative Example 1 requires pretreatment of the aqueous phase by refrigeration, which inevitably increases the number of processes and energy consumption, making it unsuitable for continuous production. The preparation process of the present invention can be completed at room temperature or under mild heating conditions, which has the advantages of simplified process and low energy consumption, and is suitable for industrial continuous production.

[0067] In summary, the DHA beverage of the present invention forms a double-layer nanoemulsion structure, which endows the beverage with multiple superior properties: it has excellent thermal stability and freeze-thaw stability, and can maintain the stability of the system under drastic temperature changes; it exhibits significant tolerance to chemical factors such as acids, alkalis, and salts, and is suitable for a variety of complex processing scenarios; it has excellent long-term storage stability, effectively extending the product's shelf life.

[0068] Based on this, the preparation process of the DHA algal oil nanoemulsion oral liquid proposed in this invention has significant advantages in improving product stability, masking undesirable flavors, and enhancing bioavailability. It effectively solves technical problems such as easy oxidation, poor stability, and unsatisfactory sensory quality of DHA during application, providing a technical foundation for the widespread application of DHA in food, health products, and other fields. These characteristics provide valuable technical reference for the development of highly stable DHA beverages and their widespread application in food processing.

[0069] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing water-in-oil microemulsion DHA algal oil, characterized in that, Includes the following steps: S1: Mix walnut oil, medium-chain triglycerides, vitamin E, and phospholipids, and stir until completely dissolved under water bath heating to obtain the oil phase; S2: Dissolve DHA algal oil, γ-aminobutyric acid, steviol glycosides, sodium caseinate, xanthan gum, Alpinia oxyphylla, hawthorn, yam, Codonopsis pilosula, bovine spleen peptide, phospholipids and chicken gizzard membrane in purified water, stir and disperse evenly to obtain an aqueous phase; S3: The aqueous phase obtained in step S2 is stirred at low speed and the oil phase obtained in step S1 is added to the aqueous phase. The mixture is stirred at high speed to form a crude emulsion. The crude emulsion is homogenized to obtain an encapsulated emulsion. The encapsulation emulsion is an oil-in-water microemulsion of DHA algal oil.

2. The method for preparing water-in-oil microemulsion DHA algal oil according to claim 1, characterized in that, In step S1: The mass ratio of walnut oil, medium-chain triglycerides, vitamin E, and phospholipids is (1~2):(0.1~1):(0.01~0.09):(0.1~0.9).

3. The method for preparing water-in-oil microemulsion DHA algal oil according to claim 1, characterized in that, In step S1: The water bath heating temperature is 55~65 ℃, and the water bath heating time is 2.5~3.5 h; The stirring rate is 450~550 r / min.

4. The method for preparing water-in-oil microemulsion DHA algal oil according to claim 1, characterized in that, In step S2: The mass ratio of DHA algal oil, γ-aminobutyric acid, steviol glycosides, sodium caseinate, xanthan gum, Alpinia oxyphylla, hawthorn, yam, Codonopsis pilosula, bovine spleen peptide, phospholipids, chicken gizzard lining and water is (3~4):(0.1~0.9):(0.01~0.1):(0.1~1):(0.1~1):(0.1~1):(0.1~1):(0.1~1):(0.1~1):(0.1~1):(0.1~1):(0.1~0.5):(0.1~1):(50~100).

5. The method for preparing water-in-oil microemulsion DHA algal oil according to claim 1, characterized in that, In step S2: The stirring and dispersion temperature is 45~55 ℃, the stirring and dispersion time is 10~20 min, and the stirring and dispersion rate is 450~550 r / min.

6. The method for preparing water-in-oil microemulsion DHA algal oil according to claim 1, characterized in that, In step S3: The low-speed stirring rate is 5000~8000 r / min; The high-speed stirring rate is 8000~12000 r / min, and the high-speed stirring time is 5~10 min.

7. The method for preparing water-in-oil microemulsion DHA algal oil according to claim 1, characterized in that, In step S3: The homogenization is performed 2 to 4 times, and the homogenization pressure is 50 to 80 MPa.

8. The method for preparing water-in-oil microemulsion DHA algal oil according to claim 1, characterized in that, In step S3: The mass ratio of the oil phase to the water phase is 1:(6~15).

9. A water-in-oil microemulsion DHA algal oil, characterized in that, It was prepared by the preparation method described in any one of claims 1 to 8; The water-in-oil microemulsion DHA algal oil described herein has a double-layer nanoemulsion structure.

10. The application of the water-in-oil microemulsion DHA algal oil as described in claim 9 in the preparation of DHA algal oil nanoemulsion oral liquid, characterized in that, It also includes step S4: S4: Mix the encapsulation emulsion obtained in step S3 with sweet orange oil flavoring and water to obtain DHA algal oil nanoemulsion oral liquid; in, The mass ratio of the encapsulating emulsion, sweet orange oil flavoring, and water is (20~46):(0.05~0.2):(53~79).

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