Porous starch-based DHA (docosahexaenoic acid) algae oil core-shell structure microcapsule as well as preparation method and application thereof

Abstract

The invention discloses a porous starch DHA algae oil core-shell structure microcapsule as well as a preparation method and application thereof. The porous microcapsule provided by the invention comprises a modified porous starch carrier, the DHA algae oil is loaded in the modified porous starch carrier; the modified porous starch carrier is coated with the outer-layer wall material, and the outer-layer wall material is one or a mixture of more of lycium barbarum polysaccharide, tremella polysaccharide, Arabic gum, pectin, sodium alginate, whey protein isolate, casein, soybean protein isolate, zein, gelatin and pea protein. The porous starch is modified, the product of the porous starch is used as a carrier of the core material, and the porous structure is used as the carrier to cooperate with the outer wall material of the polysaccharide to ensure that the DHA-embedded algal oil has oxidation resistance in a hot-pressing environment, slow release can be realized, and the storage stability of the DHA-embedded algal oil is improved.

Description

Technical Field

[0001] This invention relates to the field of core-shell microcapsules, specifically to a porous starch-based DHA algal oil core-shell microcapsule, its preparation method, and its application. Background Technology

[0002] Microencapsulation technology is used to prepare DHA algal oil into powdered microcapsules, forming a protective layer around the algal oil to achieve antioxidant effects, mask odors, and facilitate transportation. Commonly used wall materials for preparing algal oil microcapsules include xanthan gum, pectin, gum arabic, maltodextrin, gelatin, whey protein isolate, soy protein isolate, and modified starch. Common preparation methods include composite coagulation, interfacial polymerization, freeze-drying, spray drying, extrusion, and air suspension. Using single compounds and simple mixtures as emulsifiers, microcapsules prepared using traditional methods have limited emulsifying capabilities. Although they can encapsulate algal oil to a certain extent, leakage of algal oil within the microcapsules is common, significantly impacting product quality.

[0003] In this context, how to prepare algal oil microcapsule powder with high oil loading capacity, low leakage, good storage stability and oxidation stability, and simple operation process that can be industrialized is an urgent problem to be solved. Existing records document a series of studies on the preparation of algal oil microcapsules. For example, Chinese patent "CN107836716B A kind of algal oil microcapsule and its preparation and application" discloses microcapsules made from maltodextrin, corn syrup, and octenyl succinate starch, which simultaneously possess high encapsulation efficiency and oil content, but does not specifically point out the improvement of oxidation stability. Chinese patent "CN112754016B A high-stability DHA algal oil microcapsule and its preparation method" discloses microcapsules with a surface oil content below 0.39% and an encapsulation efficiency above 98.07%, which, despite high oxidation stability and encapsulation efficiency, has extremely low oil content. These patents all disclose methods for preparing algal oil microcapsules, but little attention has been paid to microcapsules that simultaneously possess high DHA content, oil loading capacity, encapsulation efficiency, and oxidation stability. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a porous starch-based DHA algal oil core-shell structured microcapsule, its preparation method, and its applications. The DHA algal oil microcapsules provided by this invention have high oil loading capacity, significantly improved stability, and a simple processing method, enabling practical applications and industrial-scale production.

[0005] The specific steps include: (1) Mix the protein and polysaccharide and stir. Use this mixture as the outer wall material of the microcapsule.

[0006] (2) Mix porous starch and algal oil and stir. The porous starch serves as the inner wall material of the microcapsules in the form of a carrier.

[0007] (3) Mix the two together and stir at high speed to form an O / W type emulsion.

[0008] (4) Spray drying of O / W type emulsion yields porous starch-based DHA algal oil microcapsules.

[0009] Preferably, the protein in step (1) is one or a mixture of several of whey protein isolate, soy protein isolate, pea protein, zein, gelatin, and casein, and the polysaccharide is one or a mixture of several of sodium alginate, chitosan, pectin, xanthan gum, and gum arabic.

[0010] Preferably, the mass ratio of protein to polysaccharide in step (1) is 1:1-6:1, the stirring time is 6-12h, and the outer wall material is 10-50 parts by weight.

[0011] Preferably, the DHA content of the algal oil in step (2) is 35%-50%.

[0012] Preferably, the mass ratio of porous starch to algal oil in step (2) is 1:4-1:1, the stirring time is 30-60 min, and the inner wall material is 20-70 parts by weight.

[0013] Preferably, the modified porous starch in step (2) is prepared by the following method: a porous starch solution with a starch milk concentration of 25-45% is prepared by weighing porous starch and adjusting the pH to 8-10 with NaOH solution; 3.5-5.5% octenyl succinic anhydride is mixed with the porous starch suspension and heated in a water bath at 35-55℃ for 1.5-3.5h; the pH is adjusted to 6-7.5 with HCl to terminate the reaction; the suspension is filtered, and the filter cake is washed 1-3 times with distilled water and anhydrous ethanol, respectively, and dried in an oven at 50-65℃, ground and sieved to obtain the modified porous starch.

[0014] Preferably, in step (3), the magnetic stirring inner core material is poured into the outer wall material, the mixture is stirred for 10-30 minutes, the high-speed homogenization speed is 8000-15000 rpm, and the high-speed homogenization time is 2-6 minutes.

[0015] Preferably, the inlet air temperature of the spray drying in step (4) is 160-180℃ and the feed rate is 300-600mL / h.

[0016] This invention also provides a porous starch-based DHA algal oil core-shell structured microcapsule, prepared by the above method.

[0017] This invention also provides the application of porous starch-based DHA algal oil core-shell structured microcapsules in the preparation of products that have antioxidant, memory-improving, memory-aiding, visual fatigue-relieving, sleep-improving, physical fatigue-relieving, hypoxia-resistant, or body fat-controlling properties.

[0018] Furthermore, the product is a food, health food, or pharmaceutical. Examples include milk powder, baked bread, gummies, soft capsules, tablets, powders, solid beverages, cheese sticks, and energy bars.

[0019] This invention also provides a method for preparing porous starch-based DHA fish oil core-shell structured microcapsules, replacing algal oil with fish oil in the aforementioned method.

[0020] This invention also provides a porous starch-based DHA fish oil core-shell structured microcapsule, prepared by the above method.

[0021] This invention also provides the application of porous starch-based DHA fish oil core-shell structured microcapsules in the preparation of products that have antioxidant, memory-improving, memory-aiding, visual fatigue-relieving, sleep-improving, physical fatigue-relieving, hypoxia-resistant, or body fat-controlling properties.

[0022] This invention also provides a method for preparing porous starch-based EPA core-shell structured microcapsules, in which algal oil is replaced with EPA oil in the aforementioned method.

[0023] The present invention also provides a porous starch-based EPA core-shell structured microcapsule, which is prepared by the above method.

[0024] This invention also provides the application of porous starch-based EPA core-shell structured microcapsules in the preparation of products that have antioxidant properties, improve memory, assist in improving memory, relieve visual fatigue, improve sleep, relieve physical fatigue, improve hypoxia tolerance, help control body fat, lower blood lipids, lower blood pressure, or assist in lowering blood lipids and lowering blood pressure.

[0025] Furthermore, the product is food, health food, or medicine.

[0026] Beneficial effects: First, compared to DHA algal oil microcapsules with single-layer wall materials, this invention uses modified porous starch as a carrier for algal oil DHA. Modified porous starch has a huge specific surface area and abundant pore structure, which firmly locks the DHA algal oil within the internal pores through physical adsorption. This achieves initial encapsulation, greatly increasing the oil loading capacity of the microcapsules and reducing surface oil, thereby improving encapsulation efficiency.

[0027] Secondly, this invention significantly improves the homogeneity and storage stability of the product through optimized processes, extending its shelf life and making it suitable for industrial production and market promotion. The outer protein-polysaccharide composite wall material forms a dense, continuous protective film that effectively blocks external environmental factors such as oxygen and light. Proteins and polysaccharides themselves are also excellent oxygen inhibitors. This "internal and external" protective system can maximally delay the oxidative rancidity of unsaturated fatty acids in DHA, significantly extending the product's shelf life. This is difficult to achieve with a single wall material system. The porous starch-based algal oil DHA core-shell structure microcapsules have an oil loading of 50-80%, an encapsulation rate of 75-95%, and a DHA content of 50-70%. During a 21-day accelerated oil oxidation experiment at 65°C, the peroxide value of the algal oil DHA microcapsules was 11.6-17.8 mmol / kg.

[0028] Third, this invention utilizes spray drying to reduce fishy odor. The adsorption effect of modified porous starch can first physically encapsulate and fix these odor molecules. The outer protein-polysaccharide wall material adds another flavor barrier, resulting in a better double masking effect and improving the taste and flavor of the final product.

[0029] Fourth, this invention achieves enteric-coated targeted release, ensuring that DHA is efficiently utilized at the optimal absorption site and avoiding unnecessary loss in the stomach.

[0030] Fifth, this invention improves the flowability of the microcapsule powder. After being loaded with oil, the modified porous starch transforms from a liquid oil into a solid powder with good flowability. This makes it less prone to sticking and clumping during subsequent processing such as spray drying, improving drying efficiency and powder yield. The resulting microcapsule powder has good flowability and is easy to mix with other food ingredients. Sixth, this invention improves bioavailability. Whey protein isolate and gum arabic can be enzymatically hydrolyzed in the intestine, and their digestion products may help form smaller, more easily absorbed oil droplets (micellarization), thereby potentially improving the bioavailability and absorption rate of DHA.

[0031] Seventh, the process of this invention is simple, the production cost is low, and it is suitable for industrial production. At the same time, it solves the problem of reusing algal by-products for DHA algal oil companies, reduces production costs, avoids environmental pollution problems, and greatly increases the added value of algal by-products.

[0032] Eighth, in the emulsion preparation stage of this invention, proteins, as excellent emulsifiers, can stabilize the oil-water interface, while polysaccharides can increase the viscosity of the aqueous phase and prevent oil droplet aggregation, laying the foundation for the preparation of high-quality microcapsules by spray drying. Proteins have good emulsifying and film-forming properties, but their mechanical strength and barrier properties are sometimes insufficient. Polysaccharides can provide good mechanical strength and stability. The combination of the two can form a denser and more robust wall structure. Attached Figure Description

[0033] Figure 1 This is a SEM image of the porous starch in Example 1.

[0034] Figure 2 This is a SEM image of the porous starch-based DHA algal oil core-shell structure microcapsule from Example 1.

[0035] Figure 3 This is a flowchart illustrating the preparation process of the porous starch-based algal oil DHA bilayer microcapsules in this invention. Detailed Implementation

[0036] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments. The content mentioned in the embodiments is not intended to limit the present invention. Example

[0037] This invention provides a core-shell structured microcapsule of DHA algal oil supported on octenyl succinic acid-modified porous starch ester and its preparation method, comprising the following components by weight: 100 parts deionized water; 10-30 parts outer wall material (shell), wherein the outer wall material comprises protein and polysaccharide; 5-25 parts modified porous starch; 35-75 parts DHA algal oil; wherein the modified porous starch is prepared by modifying porous corn starch with octenyl succinic anhydride, and the amount of octenyl succinic anhydride added is 3.5-5.5%; the porous starch is sourced from the market; The microcapsules are prepared as follows: S1. Weigh out porous starch to prepare a porous starch solution with a starch milk concentration of 30%, and adjust the pH to 8.5 with NaOH solution; mix 5% octenyl succinic anhydride with the porous starch suspension, and keep it in a beaker at 35 ℃ and magnetically stir at 200 rpm for 3 h; adjust the pH to 6.5 with HCl to terminate the reaction; filter the suspension, wash the filter cake with distilled water and anhydrous ethanol 1-3 times respectively, dry it in an oven at 55 ℃ and sieve to obtain the modified porous starch.

[0038] S2. Weigh 20 parts by weight of the modified porous starch, add algal oil and stir evenly with a glass rod, then stir at 200 rpm for 30 min to obtain a mixture; the mass ratio of the porous starch to the algal oil is 1:3.

[0039] S3. Place 20 parts by weight of whey protein isolate and gum arabic in a beaker, add deionized water and stir with a glass rod until homogeneous. Then stir at 200 rpm for 2 hours and place in a refrigerator at 4°C overnight to ensure full hydration and obtain a proteoglycan mixture as the outer wall material. The mass ratio of whey protein isolate to gum arabic is 2:1 and the mass of deionized water added is 100 parts by weight.

[0040] S4. Mix the inner core mixture with the outer wall material, and magnetically stir at 200 rpm for 10 minutes to ensure homogenization. Then, homogenize by high-speed shearing at 13000 rpm for 3 minutes. After setting the relevant spray drying parameters, immediately spray dry the homogenized emulsion. The inlet air temperature of the spray dryer is controlled at 165 ℃, the outlet air temperature is 85 ℃, the feed rate is 450 mL / h, and the atomization pressure is 0.8 MPa. The resulting microcapsule powder is then stored in a cold storage at 4 ℃ in the dark. Example

[0041] This invention provides a core-shell structured microcapsule of DHA algal oil supported on octenyl succinic acid-modified porous starch ester and its preparation method, comprising the following components by weight: 100 parts deionized water; 10-30 parts outer wall material (shell), wherein the outer wall material comprises protein and polysaccharide; 5-25 parts modified porous starch; 35-75 parts DHA algal oil; wherein the modified porous starch is prepared by modifying porous corn starch with octenyl succinic anhydride, and the amount of octenyl succinic anhydride added is 3.5-5.5%; the porous starch is sourced from the market; The microcapsules are prepared as follows: S1. Weigh out porous starch to prepare a porous starch solution with a starch milk concentration of 30%, and adjust the pH to 8.5 with NaOH solution; mix 5% octenyl succinic anhydride with the porous starch suspension, and keep it in a beaker at 35 ℃ and magnetically stir at 200 rpm for 3 h; adjust the pH to 6.5 with HCl to terminate the reaction; filter the suspension, wash the filter cake with distilled water and anhydrous ethanol 1-3 times respectively, dry it in an oven at 55 ℃ and sieve to obtain the modified porous starch.

[0042] S2. Weigh 20 parts by weight of the modified porous starch, add algal oil and stir evenly with a glass rod, then stir at 200 rpm for 30 min to obtain a mixture; the mass ratio of the porous starch to the algal oil is 1:2.

[0043] S3. Place 20 parts by weight of whey protein isolate and gum arabic in a beaker, add deionized water and stir with a glass rod until homogeneous. Then stir at 200 rpm for 2 hours and place in a refrigerator at 4°C overnight to ensure full hydration and obtain a proteoglycan mixture as the outer wall material. The mass ratio of whey protein isolate to gum arabic is 2:1 and the mass of deionized water added is 100 parts by weight.

[0044] S4. Mix the inner core mixture with the outer wall material, and magnetically stir at 200 rpm for 10 minutes to ensure homogenization. Then, homogenize by high-speed shearing at 13000 rpm for 3 minutes. After setting the relevant spray drying parameters, immediately spray dry the homogenized emulsion. The inlet air temperature of the spray dryer is controlled at 165 ℃, the outlet air temperature is 85 ℃, the feed rate is 450 mL / h, and the atomization pressure is 0.8 MPa. The resulting microcapsule powder is then stored in a cold storage at 4 ℃ in the dark. Example

[0045] This invention provides a core-shell structured microcapsule of DHA algal oil supported on octenyl succinic acid-modified porous starch ester and its preparation method, comprising the following components by weight: 100 parts deionized water; 10-30 parts outer wall material (shell), wherein the outer wall material comprises protein and polysaccharide; 5-25 parts modified porous starch; 35-75 parts DHA algal oil; wherein the modified porous starch is prepared by modifying porous corn starch with octenyl succinic anhydride, and the amount of octenyl succinic anhydride added is 3.5-5.5%; the porous starch is sourced from the market; The microcapsules are prepared as follows: S1. Weigh out porous starch to prepare a porous starch solution with a starch milk concentration of 30%, and adjust the pH to 8.5 with NaOH solution; mix 5% octenyl succinic anhydride with the porous starch suspension, and keep it in a beaker at 35 ℃ and magnetically stir at 200 rpm for 3 h; adjust the pH to 6.5 with HCl to terminate the reaction; filter the suspension, wash the filter cake with distilled water and anhydrous ethanol 1-3 times respectively, dry it in an oven at 55 ℃ and sieve to obtain the modified porous starch.

[0046] S2. Weigh 20 parts by weight of the modified porous starch, add algal oil and stir evenly with a glass rod, then stir at 200 rpm for 30 min to obtain a mixture; the mass ratio of the porous starch to the algal oil is 1:1.

[0047] S3. Place 20 parts by weight of whey protein isolate and gum arabic in a beaker, add deionized water and stir with a glass rod until homogeneous. Then stir at 200 rpm for 2 hours and place in a refrigerator at 4°C overnight to ensure full hydration and obtain a proteoglycan mixture as the outer wall material. The mass ratio of whey protein isolate to gum arabic is 2:1 and the mass of deionized water added is 100 parts by weight.

[0048] S4. Mix the inner core mixture with the outer wall material, and magnetically stir at 200 rpm for 10 minutes to ensure homogenization. Then, homogenize by high-speed shearing at 13000 rpm for 3 minutes. After setting the relevant spray drying parameters, immediately spray dry the homogenized emulsion. The inlet air temperature of the spray dryer is controlled at 165 ℃, the outlet air temperature is 85 ℃, the feed rate is 450 mL / h, and the atomization pressure is 0.8 MPa. The resulting microcapsule powder is then stored in a cold storage at 4 ℃ in the dark. Example

[0049] This invention provides a core-shell structured microcapsule of DHA algal oil supported on octenyl succinic acid-modified porous starch ester and its preparation method, comprising the following components by weight: 100 parts deionized water; 10-30 parts outer wall material (shell), wherein the outer wall material comprises protein and polysaccharide; 5-25 parts modified porous starch; 35-75 parts DHA algal oil; wherein the modified porous starch is prepared by modifying porous corn starch with octenyl succinic anhydride, and the amount of octenyl succinic anhydride added is 3.5-5.5%; the porous starch is sourced from the market; The microcapsules are prepared as follows: S1. Weigh out porous starch to prepare a porous starch solution with a starch milk concentration of 30%, and adjust the pH to 8.5 with NaOH solution; mix 5% octenyl succinic anhydride with the porous starch suspension, and keep it in a beaker at 35 ℃ and magnetically stir at 200 rpm for 3 h; adjust the pH to 6.5 with HCl to terminate the reaction; filter the suspension, wash the filter cake with distilled water and anhydrous ethanol 1-3 times respectively, dry it in an oven at 55 ℃ and sieve to obtain the modified porous starch.

[0050] S2. Weigh 10 parts by weight of the modified porous starch, add algal oil and stir evenly with a glass rod, then stir at 200 rpm for 30 minutes to obtain a mixture; the mass ratio of the porous starch to the algal oil is 1:3.

[0051] S3. Place 12 parts by weight of soy protein isolate and gum arabic in a beaker, add deionized water and stir with a glass rod until homogeneous. Then stir at 200 rpm for 2 hours and place in a refrigerator at 4°C overnight to ensure full hydration and obtain a protein-polysaccharide mixture as the outer wall material. The mass ratio of whey protein isolate to gum arabic is 1:1 and the mass of deionized water added is 100 parts by weight.

[0052] S4. Mix the inner core mixture with the outer wall material, and magnetically stir at 200 rpm for 10 minutes to ensure homogenization. Then, homogenize by high-speed shearing at 13000 rpm for 3 minutes. After setting the relevant spray drying parameters, immediately spray dry the homogenized emulsion. The inlet air temperature of the spray dryer is controlled at 165 ℃, the outlet air temperature is 85 ℃, the feed rate is 450 mL / h, and the atomization pressure is 0.8 MPa. The resulting microcapsule powder is then stored in a cold storage at 4 ℃ in the dark. Example

[0053] This invention provides a core-shell structured microcapsule of DHA algal oil supported on octenyl succinic acid-modified porous starch ester and its preparation method, comprising the following components by weight: 100 parts deionized water; 10-30 parts outer wall material (shell), wherein the outer wall material comprises protein and polysaccharide; 5-25 parts modified porous starch; 35-75 parts DHA algal oil; wherein the modified porous starch is prepared by modifying porous corn starch with octenyl succinic anhydride, and the amount of octenyl succinic anhydride added is 3.5-5.5%; the porous starch is sourced from the market; The microcapsules are prepared as follows: S1. Weigh out porous starch to prepare a porous starch solution with a starch milk concentration of 30%, and adjust the pH to 8.5 with NaOH solution; mix 5% octenyl succinic anhydride with the porous starch suspension, and keep it in a beaker at 35 ℃ and magnetically stir at 200 rpm for 3 h; adjust the pH to 6.5 with HCl to terminate the reaction; filter the suspension, wash the filter cake with distilled water and anhydrous ethanol 1-3 times respectively, dry it in an oven at 55 ℃ and sieve to obtain the modified porous starch.

[0054] S2. Weigh 10 parts by weight of the modified porous starch, add algal oil and stir evenly with a glass rod, then stir at 200 rpm for 30 min to obtain a mixture; the mass ratio of the porous starch to the algal oil is 1:2.

[0055] S3. Place 12 parts by weight of soy protein isolate and gum arabic in a beaker, add deionized water and stir with a glass rod until homogeneous. Then stir at 200 rpm for 2 hours and place in a refrigerator at 4°C overnight to ensure full hydration and obtain a protein-polysaccharide mixture as the outer wall material. The mass ratio of whey protein isolate to gum arabic is 1:1 and the mass of deionized water added is 100 parts by weight.

[0056] S4. Mix the inner core mixture with the outer wall material, and magnetically stir at 200 rpm for 10 minutes to ensure homogenization. Then, homogenize by high-speed shearing at 13000 rpm for 3 minutes. After setting the relevant spray drying parameters, immediately spray dry the homogenized emulsion. The inlet air temperature of the spray dryer is controlled at 165 ℃, the outlet air temperature is 85 ℃, the feed rate is 450 mL / h, and the atomization pressure is 0.8 MPa. The resulting microcapsule powder is then stored in a cold storage at 4 ℃ in the dark. Example

[0057] This invention provides a core-shell structured microcapsule of DHA algal oil supported on octenyl succinic acid-modified porous starch ester and its preparation method, comprising the following components by weight: 100 parts deionized water; 10-30 parts outer wall material (shell), wherein the outer wall material comprises protein and polysaccharide; 5-25 parts modified porous starch; 35-75 parts DHA algal oil; wherein the modified porous starch is prepared by modifying porous corn starch with octenyl succinic anhydride, and the amount of octenyl succinic anhydride added is 3.5-5.5%; the porous starch is sourced from the market; The microcapsules are prepared as follows: S1. Weigh out porous starch to prepare a porous starch solution with a starch milk concentration of 30%, and adjust the pH to 8.5 with NaOH solution; mix 5% octenyl succinic anhydride with the porous starch suspension, and keep it in a beaker at 35 ℃ and magnetically stir at 200 rpm for 3 h; adjust the pH to 6.5 with HCl to terminate the reaction; filter the suspension, wash the filter cake with distilled water and anhydrous ethanol 1-3 times respectively, dry it in an oven at 55 ℃ and sieve to obtain the modified porous starch.

[0058] S2. Weigh 10 parts by weight of the modified porous starch, add algal oil and stir evenly with a glass rod, then stir at 200 rpm for 30 min to obtain a mixture; the mass ratio of the porous starch to the algal oil is 1:1.

[0059] S3. Place 12 parts by weight of soy protein isolate and gum arabic in a beaker, add deionized water and stir with a glass rod until homogeneous. Then stir at 200 rpm for 2 hours and place in a refrigerator at 4°C overnight to ensure full hydration and obtain a protein-polysaccharide mixture as the outer wall material. The mass ratio of whey protein isolate to gum arabic is 1:1 and the mass of deionized water added is 100 parts by weight.

[0060] S4. Mix the inner core mixture with the outer wall material, and magnetically stir at 200 rpm for 10 min to ensure homogenization. Then, homogenize by high-speed shearing at 13000 rpm for 3 min. After setting the relevant spray drying parameters, immediately spray dry the homogenized emulsion. The inlet air temperature of the spray dryer is controlled at 165 ℃, the outlet air temperature is 85 ℃, the feed rate is 450 mL / h, and the atomization pressure is 0.8 MPa. The resulting microcapsule powder is then stored in a cold storage at 4 ℃ in the dark.

[0061] Comparative Example 1 A single-layer microcapsule is prepared by the following steps: (1) Aqueous phase preparation: Dissolve whey protein isolate in deionized water, stir at 200 rpm for 2 hours, and then place in a refrigerator at 4°C overnight to ensure full hydration.

[0062] (2) Preparation of oil phase: Place algal oil in a beaker.

[0063] (3) Emulsion preparation: Mix the emulsion from step (1) with the oil phase, stir magnetically at 200 rpm for 10 min to make it uniform, and then homogenize it by high-speed shearing at 13000 rpm for 3 min.

[0064] (4) Spray drying: After setting the relevant parameters for spray drying, the homogenized emulsion was immediately spray dried. The inlet air temperature for spray drying was controlled at 165 ℃, the outlet air temperature was 85 ℃, the feed rate was 450 mL / h, and the atomization pressure was 0.8 MPa, finally obtaining microcapsule powder.

[0065] Comparative Example 2 The difference between Comparison 2 and Example 1 is that the same mass fraction of unmodified porous starch was added, while the rest was the same as in Example 1.

[0066] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that gum arabic was not added; otherwise, they are the same as Example 1.

[0067] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that no modified porous starch was added; otherwise, they are the same as Example 1.

[0068] Comparative Example 5 The difference between Comparative Example 5 and Example 4 is that gum arabic was not added; otherwise, they are the same as Example 1.

[0069] Comparative Example 6 The difference between Comparative Example 6 and Example 4 is that no modified porous starch was added; otherwise, they are the same as Example 1.

[0070] Sensory evaluation Sensory evaluation method: The microcapsule powders of Examples 1-6 and Comparative Examples 1-5 were sensory evaluated according to the microcapsule sensory scoring criteria in Table 1. The sensory scoring results are shown in Table 2.

[0071] Table 1 Sensory evaluation criteria for microcapsules (unit: points)

[0072] Table 2 Sensory evaluation results of the microcapsule powders of Examples 1-6 and Comparative Examples 1-5

[0073] As shown in Table 2, the sensory score of the single-layer microcapsules in Comparative Example 1 was lower. This is because the color of ordinary single-layer microcapsules was not uniform enough and was yellowish, with a certain fishy smell. The microcapsule powders in Comparative Examples 2-6 demonstrated the synergistic effect of both proteins and polysaccharides. The adsorption effect of modified porous starch can first physically encapsulate and fix these odor molecules. The outer protein-polysaccharide wall material adds another flavor barrier, resulting in a better double masking effect and improving the taste and flavor of the final product. Therefore, the sensory score of the microcapsule powder was greatly improved.

[0074] Determination of surface oil, total oil, and encapsulation ratio The specific measurement method is as follows: 1) Determination of surface oil: Refer to SC / T3505-2006 for determination, with appropriate modifications. Add approximately 1 g of microcapsules to 15 ml of petroleum ether (boiling range 30-60℃), shake for 1 min, then centrifuge at 3000 r / min for 5 min, and collect the supernatant. In a fume hood, place the supernatant in a 60℃ water bath (using distilled water) to remove the solvent, and then dry in an oven at 105℃ until constant weight. Collect the residual oil and weigh it. Calculate the surface oil content using the formula: 2) Determination of total oil: Add approximately 1 g of microcapsules to 30 mL of petroleum ether (boiling range 30-60℃), sonicate for 10 min, and centrifuge at 6000 r / min for 10 min to collect the supernatant. In a fume hood, place the supernatant in a 60℃ water bath (using distilled water) to remove the solvent, and then dry it in an oven at 105℃ until constant weight. Weigh the remaining oil, and calculate the total oil using the formula: 3) Determination of encapsulation rate: The encapsulation rate of the powder is calculated based on the oil loading and surface oil content of the powder. The calculation formula is as follows: The specific results are shown in Table 3.

[0075] Table 3. Results of surface oil, total oil, and encapsulation efficiency determination of microcapsules in Examples 1-6 and Comparative Examples 2-6

[0076] As shown in Table 3, the encapsulation rate of Example 1 is higher than that of Example 6, indicating that the increased amount of algal oil added improves the adsorption capacity of modified porous starch for DHA algal oil. The physical adsorption effect of the porous structure significantly increases the oil loading capacity of the microcapsules, reduces surface oil, and thus improves the encapsulation efficiency. Comparative Examples 6, 3, and 5 have lower encapsulation rates compared to Examples 1 and 4, indicating that the modified porous starch has enhanced oil adsorption capacity. This is mainly due to the esterification reaction between octenyl succinic anhydride (OSA) and the hydroxyl groups of the porous starch to generate lipophilic ester groups, resulting in stronger adsorption of DHA algal oil and increasing the total oil content, thereby improving the encapsulation rate.

[0077] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0078] It should be understood that the above detailed description of the technical solutions of the present invention with reference to preferred embodiments is illustrative and not restrictive. Those skilled in the art can modify the technical solutions described in the embodiments or make equivalent substitutions for some of the technical features based on reading this specification; however, these modifications or substitutions do not cause the essence of the corresponding technical solutions to depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing porous starch-based DHA algal oil core-shell structured microcapsules, characterized in that, Includes the following steps: (1) Mix the protein and polysaccharide and stir. Use this mixture as the outer wall material of the microcapsule. (2) Mix porous starch and algal oil and stir. The porous starch is used as the inner wall material of the microcapsule in the form of a carrier. (3) Mix the two together and homogenize them at high speed to form an O / W type emulsion; (4) Spray drying of O / W type emulsion yields porous starch-based DHA algal oil microcapsules.

2. The method for preparing porous starch-based DHA algal oil core-shell structured microcapsules according to claim 1, characterized in that, In step (1), the protein is one or a mixture of several of whey protein isolate, soy protein isolate, pea protein, zein, gelatin, and casein, and the polysaccharide is one or a mixture of several of sodium alginate, chitosan, pectin, xanthan gum, and gum arabic.

3. The method for preparing porous starch-based DHA algal oil microcapsules according to claim 1, characterized in that, The porous starch is prepared by the following method: The porous corn starch was modified with octenyl succinic anhydride, and the amount of octenyl succinic anhydride added was 3.5~5.5%.

4. The method for preparing porous starch-based DHA algal oil core-shell structured microcapsules according to claim 3, characterized in that, First stage: Treatment with alkenyl succinic anhydride at pH 8-9 for 2.5-3.5 hours; Second stage: Adjust the pH to 6.5-7.5 to terminate the reaction, and filter, wash, dry and sieve the suspension.

5. The method for preparing porous starch-based DHA algal oil core-shell structured microcapsules according to claim 3, characterized in that, A porous starch solution with a starch milk concentration of 25-45% was prepared by weighing porous starch and adjusting the pH to 8-10 with NaOH solution. 3.5-5.5% octenyl succinic anhydride was mixed with the porous starch suspension and heated in a water bath at 35-55℃ for 1.5-3.5 h. The pH was adjusted to 6-7.5 with HCl to terminate the reaction. The suspension was filtered, and the filter cake was washed 1-3 times with distilled water and anhydrous ethanol, respectively. It was then dried in an oven at 50-65℃ and sieved to obtain the porous starch.

6. The method for preparing porous starch-based DHA algal oil core-shell structured microcapsules according to claim 1, characterized in that, The porous starch in step (2) is one or a mixture of several of the following: rice porous starch, corn porous starch, wheat porous starch, barley porous starch, cassava porous starch, potato porous starch, and kudzu porous starch.

7. The method for preparing porous starch-based DHA algal oil core-shell structured microcapsules according to claim 1, characterized in that... In step (1), the mass ratio of protein to polysaccharide is 1:1 to 6:1, and the stirring time is 6 to 12 hours. and / or In step (2), the mass ratio of porous starch to algal oil is 1:4 to 1:1, and the stirring time is 30 to 60 minutes. and / or In step (3), the high-speed homogenization speed is 8000~15000 rpm, and the high-speed homogenization time is 2~6 min; and / or In step (4), the inlet air temperature for spray drying is 160~180℃, and the feed rate is 300~600 mL / h.

8. Porous starch-based DHA algal oil core-shell structured microcapsules were prepared according to any one of claims 1-7.

9. The application of the porous starch-based DHA algal oil core-shell structure microcapsules according to claim 8 in the preparation of products that have antioxidant, memory-improving, memory-aiding, visual fatigue-relieving, sleep-improving, physical fatigue-relieving, hypoxia-resistant, or body fat-controlling properties.

10. A method for preparing porous starch-based DHA fish oil core-shell structured microcapsules, characterized in that, Replace the algal oil in claims 1-7 with fish oil.

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