A core-shell limited structure of euphausia superba oil composite gel ball and a preparation method and application thereof

Abstract

This invention discloses a core-shell confined Antarctic krill oil composite gel sphere and its preparation method, belonging to the field of marine food manufacturing technology. Based on a thermoreversible agar gel network, cellulose nanocrystals are introduced. Utilizing their rigid framework reinforcement and hydrogen bonding with agar molecular chains, the association of gel segments, network densification, and shell reinforcement processes are controlled to construct a composite gel shell with strong thermal processing adaptability, good spatial continuity, and high mechanical load-bearing capacity. This gel shell is formed through coaxial drop casting and low-temperature gelation, achieving a steady-state transformation of Antarctic krill oil from a fluid, easily oxidized oil to a core-shell confined gel sphere. The resulting gel spheres have a complete structure and high mechanical strength. The physical barrier effect of the densified shell can delay the migration of external oxidizing factors to the oil core, slowing the accumulation of primary and secondary oxidation products. Furthermore, the preparation is simple, does not involve organic solvents, and has industrial production potential. It can be used for the encapsulation, storage protection, and delivery of food active lipids.

Description

Technical Field

[0001] This invention belongs to the field of marine food manufacturing technology, specifically relating to a core-shell confined Antarctic krill oil composite gel ball and its preparation method. Background Technology

[0002] Antarctic krill oil is a natural marine-derived functional oil rich in phospholipid-type omega-3 polyunsaturated fatty acids and astaxanthin, boasting high nutritional value and broad application prospects. However, its highly unsaturated lipid structure, while providing nutritional advantages, also makes Antarctic krill oil highly susceptible to oxidative degradation during processing and storage, leading to loss of active ingredients and a decline in product quality, thus limiting its further development and application. Therefore, developing structurally stable encapsulation systems with good barrier properties to enhance its oxidative stability is an important technical approach to expanding the application of Antarctic krill oil in the food and related fields.

[0003] As shown in the following patent: Application No.: 202410801038.2, Publication No.: CN118356406A, Invention Title: "Antarctic Krill Oil Soft Capsules, Capsule Shell and Preparation Method Thereof", this patent discloses an Antarctic krill oil soft capsule and its preparation method. The capsule shell has good mechanical properties and water and light blocking properties. However, the encapsulation system based on animal-derived gelatin is prone to self-crosslinking and aging during storage, producing a tough, water-insoluble film that hinders the release and dissolution of Antarctic krill oil. Furthermore, its animal origin limits its application in specific consumer groups.

[0004] For example, patent application number 202510408228.2 and publication number CN120393873A discloses a method for preparing gelled Antarctic krill oil microcapsules. This method uses an oleogel formed by glyceryl laurate and Antarctic krill oil as the core material, and a mixture of concentrated milk protein, whey powder, and corn syrup as the wall material, preparing microcapsules through spray drying. This method can improve the unpleasant odor of Antarctic krill oil, but the high inlet air temperature during preparation may affect the stability of the active ingredients in the Antarctic krill oil. Furthermore, the mechanical strength and barrier properties of the membrane structure formed by the protein-syrup composite wall material are insufficient to meet the stability requirements of Antarctic krill oil under complex processing and long-term storage conditions.

[0005] The article "The complex coacervation of gum Arabic and krill protein isolate and their application for Antarctic krill oil encapsulation" discloses a method for encapsulating Antarctic krill oil using a complex coagulation technique with Antarctic krill isolated protein and gum arabic. This method can mask the fishy odor of krill oil and improve its oxidative stability; however, the complex coagulation process mainly relies on the electrostatic interaction between the two polymers and is sensitive to the pH of the system. Furthermore, the grinding process used in preparing the solid microcapsules can damage the microstructure of the microcapsules, and the capsule wall formed by the protein and polysaccharide complex lacks a rigid reinforcing framework, making it difficult to maintain the long-term integrity and stability of the capsule wall structure under complex external processing stresses.

[0006] As mentioned above, existing Antarctic krill oil encapsulation and stabilization technologies still have shortcomings in terms of wall material applicability, preparation conditions, and capsule wall barrier performance. Therefore, there is an urgent need to develop an Antarctic krill oil encapsulation system that is mild in process, structurally stable, and has good mechanical strength and storage protection effects to achieve its stable application. Summary of the Invention

[0007] The purpose of this invention is to provide a core-shell confined Antarctic krill oil composite gel sphere and its preparation method, so as to overcome the shortcomings of existing Antarctic krill oil encapsulation systems in terms of processing and molding properties, shell structure integrity, mechanical load-bearing capacity and storage protection effect.

[0008] The technical principle of this invention: The Antarctic krill oil composite gel spheres of this invention confine Antarctic krill oil within a composite gel shell, transforming the fluid and easily oxidized Antarctic krill oil into a structurally stable, easily stored, and applicable gel-encapsulated form. The preparation method is based on a thermoreversible agar gel network, introducing cellulose nanocrystals. Utilizing the rigid framework reinforcement effect of cellulose nanocrystals and their hydrogen-bonded coupling with agar molecular chains, the association of gel segments, network densification, and shell reinforcement processes are controlled, constructing a composite gel shell with strong thermal processing adaptability, good spatial continuity, and high mechanical load-bearing capacity. This gel shell is formed through coaxial drop preparation and low-temperature gelation, achieving a stable transformation of Antarctic krill oil from a fluid and easily oxidized oil into a core-shell confined gel sphere.

[0009] To achieve the above objectives, the present invention specifically adopts the following technical solution: This invention provides a method for preparing core-shell confined Antarctic krill oil composite gel spheres, specifically including the following steps: (1) Disperse cellulose nanocrystals in water at a concentration of 0.25%~1.0%, and prepare a cellulose nanocrystal dispersion by ultrasonic treatment with a pulse probe at a power of 200~300W for 25min. (2) Add agar to the cellulose nanocrystal dispersion to make the concentration of agar 2.0%~3.0%, hydrate for 5~15 min, heat to 95℃ and hold at this temperature for 15 min to obtain an agar-cellulose nanocrystal composite hot solution, which is used as a wall material adhesive; (3) Transfer the wall material adhesive to the wall material storage unit of the coaxial dripping device and keep it at 70~80°C to maintain the hot solution state; (4) Antarctic krill oil is added as the core liquid to the core material storage unit of the coaxial dripping device; (5) The wall material adhesive and core liquid are dripped through a coaxial double-hole nozzle with an inner needle diameter of 1.2 mm and an outer needle inner diameter of 2 mm to form core-shell droplets; (6) The core-shell liquid is dropped into a medium-chain triglyceride at 5~15℃ and cooled to gel, forming a core-shell wet gel ball; (7) The obtained core-shell wet gel balls were dried in a drum for 3 hours to obtain core-shell confined Antarctic krill oil composite gel balls.

[0010] Preferably, in step (1), the concentration of the cellulose nanocrystal dispersion is 0.25%, 0.5%, 0.75%, or 1.0%; Preferably, in step (1), the ultrasonic power of the probe-type ultrasonic treatment is 250W; the treatment method is ultrasonic 2s, intermittent 2s cycle.

[0011] Preferably, in step (2), the concentration of agar in the composite hot solution is 2.5%; and the stirring hydration time is 10 min.

[0012] Preferably, in step (3), the insulation temperature of the wall material adhesive in the wall material storage unit is 75°C.

[0013] Preferably, in step (5), during the dripping process, the rotation speed of the wall material adhesive delivery pump is 200 r / min, and the rotation speed of the core liquid delivery pump is 180 r / min.

[0014] Preferably, in step (6), the temperature of the medium-chain triglyceride is 10°C.

[0015] Preferably, in step (7), the air temperature of the drum drying is 25°C.

[0016] On the other hand, the present invention also provides a core-shell confined structure of Antarctic krill oil composite gel spheres. The composite gel spheres are prepared by the above-described method, and each sphere comprises an Antarctic krill oil core layer and an agar-cellulose nanocrystal composite gel shell layer covering the Antarctic krill oil core layer. The composite gel shell layer can continuously encapsulate the Antarctic krill oil core layer, transforming the fluid oil into a core-shell gel encapsulation structure with a stable external morphology.

[0017] The present invention also provides the application of the above-mentioned core-shell confined Antarctic krill oil composite gel spheres in the preparation of Antarctic krill oil encapsulated products, food compositions for improving the oxidative stability of Antarctic krill oil, or food active lipid delivery systems.

[0018] Unlike existing technologies, this invention uses an agar gel network as the basis for shell formation and introduces cellulose nanocrystals as a reinforcing component. Cellulose nanocrystals possess a rigid nanoskeleton and abundant surface hydroxyl groups, allowing them to participate in the construction of the composite network within the continuous agar phase, promoting the continuity and densification of the gel shell structure. The resulting core-shell gel spheres maintain food applicability and ease of low-temperature molding while improving the structural integrity, mechanical load-bearing capacity, and resistance to the migration of external oxidizing factors, thus benefiting the storage, preservation, and subsequent delivery of Antarctic krill oil.

[0019] Compared with the prior art, the present invention has the following beneficial effects: (1) No organic solvents and chemical crosslinking agents are required in the preparation process of this invention. The process is green, environmentally friendly, safe and controllable, with mild conditions and simple operation.

[0020] (2) The raw materials used in this invention are widely available and easy to obtain, have good food safety and food applicability, and are suitable for large-scale industrial production and promotion, providing a new technical approach for the development of Antarctic krill oil packaged products.

[0021] (3) The cellulose nanocrystals used in this invention can increase the apparent viscosity of the wall material adhesive and enhance its shear thinning properties during the hot melt stage, which is beneficial to stable transport and droplet formation during coaxial droplet preparation. During the cooling gelation process, the cellulose nanocrystals can serve as a rigid reinforcing skeleton and promote the formation of gel network and shell densification through the hydrogen bonding between the surface hydroxyl groups and the agar molecular chains, thereby improving the continuity and structural stability of the gel shell.

[0022] (4) The composite gel spheres obtained in the embodiments of the present invention have high mechanical strength, which is beneficial to maintaining the spherical structure and shell integrity during processing, transportation and storage, and reducing the risk of Antarctic krill oil leakage or direct exposure to the external environment due to shell damage.

[0023] (5) The composite gel shell formed by the present invention can serve as an effective physical barrier to prevent external oxidizing factors from migrating to the core layer of Antarctic krill oil, delay the oxidative deterioration of Antarctic krill oil and improve its oxidative stability.

[0024] (6) This invention transforms fluid and easily oxidized Antarctic krill oil into gel spheres with a core-shell confined structure through coaxial dripping and low-temperature gelation, which is beneficial for subsequent processing, transportation, storage and application.

[0025] (7) The Antarctic krill oil composite gel spheres with core-shell confined structure obtained by the present invention have food applicability, structural integrity, mechanical load-bearing capacity and oxidation barrier properties. They can be applied to Antarctic krill oil encapsulated products, food compositions that improve the oxidation stability of oils and fats, and food active lipid delivery systems, providing a new technical solution for the storage, protection, processing and delivery of functional oils. Attached Figure Description

[0026] Figure 1 This is a graph showing the apparent viscosity of the hot solutions obtained in the comparative examples and Examples 1-4.

[0027] Figure 2 This is a graph showing the changes in energy storage modulus and energy dissipation modulus during the cooling process of the hot solutions obtained in the comparative examples and Examples 1-4.

[0028] Figure 3 This is a stress-strain curve diagram of the gels obtained in comparative examples and Examples 1-4.

[0029] Figure 4 This is a moisture distribution diagram of the gels obtained in the comparative examples and Examples 1-4.

[0030] Figure 5 The diagram shows the microstructure of the gels obtained in the comparative examples and Examples 1-4.

[0031] Figure 6 The X-ray diffraction patterns are those of the gels obtained in comparative examples and Examples 1-4.

[0032] Figure 7 The infrared spectra of the gels obtained in comparative examples and Examples 1-4 are shown.

[0033] Figure 8 This is a differential scanning calorimetry curve of the gels obtained in the comparative examples and Examples 1-4.

[0034] Figure 9 The thermogravimetric curves of the gels obtained in the comparative examples and Examples 1-4 are shown.

[0035] Figure 10 This is a micro-thermogravimetric curve of the gels obtained in the comparative examples and Examples 1-4.

[0036] Figure 11 The values ​​are the hardness values ​​of the core-shell gel spheres obtained in the comparative example and Example 2.

[0037] Figure 12 The peroxide values ​​are those of the core-shell gel spheres and krill oil obtained in the comparative example and Example 2.

[0038] Figure 13 The values ​​of thiobarbituric acid in the core-shell gel spheres and krill oil obtained in the comparative example and Example 2 are shown. Detailed Implementation

[0039] The present invention will be further described below with reference to embodiments. It should be noted that these embodiments are only used to better understand and illustrate the technical solution and beneficial effects of the present invention, and should not be construed as limiting the scope of protection of the present invention.

[0040] Comparative example: Agar powder was weighed and added to deionized water to prepare a 2.5% solution. After stirring and hydrating for 10 minutes, the solution was heated to 95°C and stirred for 15 minutes to obtain a hot agar solution. A portion of the hot solution was allowed to stand at 25°C for 2 hours and then placed at 4°C for 24 hours to obtain an agar gel sample. The remaining hot solution was added to the wall material storage unit of a coaxial dripping device and kept at 75°C. Antarctic krill oil was added to the core material storage unit. Both were concentrically dripped into a 10°C medium-chain triglyceride bath through a coaxial double-hole nozzle with an inner needle diameter of 1.2 mm and an outer needle diameter of 2 mm, under conditions of a wall material adhesive delivery pump speed of 200 r / min and a core liquid delivery pump speed of 180 r / min, to form wet gel spheres. The gel spheres were then dried in a drum at 25°C for 3 hours to obtain Antarctic krill oil core-shell gel spheres.

[0041] Example 1: Cellulose nanocrystals were weighed and added to deionized water to prepare a 0.25% dispersion. The dispersion was then subjected to ultrasonic dispersion using a probe-type ultrasonic generator at a power of 250W, with a 2-second ultrasonic cycle followed by a 2-second intermittent cycle for 25 minutes to obtain the cellulose nanocrystal dispersion. Agar powder was added to the dispersion to achieve an agar concentration of 2.5%. After stirring and hydration for 15 minutes, the mixture was heated to 95°C and stirred for 10 minutes to obtain an agar-cellulose nanocrystal composite hot solution. A portion of the composite hot solution was allowed to stand at 25°C for 2 hours and then placed at 4°C for 24 hours to obtain a composite gel sample. The remaining hot solution was added to the wall material storage unit of a coaxial dripping device and maintained at 75°C. Antarctic krill oil was added to the core material storage unit. Both are concentrically dripped into a 10°C medium-chain triglyceride bath through a coaxial double-hole nozzle with an inner needle diameter of 1.2 mm and an outer needle diameter of 2 mm, under the conditions of a wall material adhesive delivery pump speed of 200 r / min and a core liquid delivery pump speed of 180 r / min, to form wet gel balls. After being dried in a drum at 25°C for 3 hours, Antarctic krill oil core-shell gel balls are obtained.

[0042] Example 2: The difference between this embodiment and Example 1 is that the concentration of cellulose nanocrystals is 0.5%, while the remaining steps and conditions are the same as in Example 1.

[0043] Example 3: The difference between this embodiment and Example 1 is that the concentration of cellulose nanocrystals is 0.75%, while the remaining steps and conditions are the same as in Example 1.

[0044] Example 4: The difference between this embodiment and Example 1 is that the concentration of cellulose nanocrystals is 1.0%, while the remaining steps and conditions are the same as in Example 1.

[0045] Experimental Example 1: Apparent Viscosity Measurement The apparent viscosity of a hot solution as a function of shear rate was determined using a steady-state shear mode at 75 °C.

[0046] Depend on Figure 1 As can be seen, the apparent viscosity of the example sample was higher than that of the comparative sample throughout the entire tested shear rate range, and the example sample exhibited a more pronounced shear thinning. This indicates that the introduction of cellulose nanocrystals can increase the apparent viscosity of the composite hot solution and improve its shear response characteristics, enabling the wall material adhesive to maintain its structure better during droplet detachment from the nozzle and during the forming process, which is conducive to the stable formation of core-shell droplets.

[0047] Experiment Example 2: Dynamic Temperature Scan The test program was set to cooling scan mode, with a cooling range of 90~20℃ and a cooling rate of 1℃ / min. The changes in energy storage modulus and energy dissipation modulus with temperature were recorded.

[0048] Depend on Figure 2 As can be seen, the energy storage modulus and energy dissipation modulus values ​​of the example sample are both higher than those of the comparative sample at the same temperature, and the modulus increases with the addition of cellulose nanocrystals. This difference is more pronounced in the low-temperature range, indicating that the introduction of cellulose nanocrystals improves the overall mechanical strength of the gel network. Simultaneously, the addition of cellulose nanocrystals shifts the intersection point of the energy storage modulus and energy dissipation modulus curves to higher temperatures, indicating that the presence of cellulose nanocrystals promotes the orderly association process of agar molecular chains in the system.

[0049] Experimental Example 3: Determination of Mechanical Properties A single compression failure test was performed on the gel sample at 25°C using a texture analyzer.

[0050] Depend on Figure 3 It is evident that, under the same strain conditions, the stress value of the example sample is higher than that of the comparative sample, and the steepness of the curve of the example sample is better than that of the comparative sample, indicating that the introduction of cellulose nanocrystals enhances the structural resistance of the gel network under large compressive deformation.

[0051] Experiment Example 4: Moisture Distribution Measurement A low-field nuclear magnetic resonance spectrometer was used to acquire transverse relaxation signals using CPMG pulse sequences, and the relaxation time T2 distribution was obtained by inversion.

[0052] Depend on Figure 4 It can be seen that the T of the example sample 22 The wider peak shape and improved symmetry indicate that the introduction of cellulose nanocrystals leads to a more uniform water distribution within the gel network and enhances the continuity of the network structure. With further increases in cellulose nanocrystal content, T... 22 The narrowing of the peaks indicates that the spatial constraint of the network on water is enhanced, and the structural density is improved.

[0053] Experimental Example 5 Micromorphology After freeze-drying, the gel samples were sputter-coated with gold, and their microstructure was observed using a scanning electron microscope.

[0054] Depend on Figure 5 As can be seen, the gels obtained in Examples 1 and 2 form a more uniform honeycomb porous network structure, with more consistent pore sizes, more uniform pore wall thickness, and enhanced connectivity between pores, resulting in a higher degree of regularity and density in the overall network. The gels obtained in Examples 3 and 4 show increased pore sizes and correspondingly increased pore wall thickness, with the network structure transforming from a fine honeycomb structure to a coarser porous framework. The gel framework is more continuous and complete than that of the comparative example, and the pore wall structure is more robust.

[0055] Experimental Example 6: X-ray Diffraction Analysis X-ray diffraction was used to analyze the freeze-dried and powdered gel samples.

[0056] Depend on Figure 6 As can be seen, the gel in the example retains the diffuse peak while exhibiting a sharp diffraction peak at the characteristic diffraction position of cellulose type I crystals, indicating that the cellulose nanocrystals maintain their original crystalline structure within the gel matrix. Simultaneously, the position of the amorphous diffuse peak did not shift significantly, indicating good structural compatibility between the cellulose nanocrystals and the agar matrix.

[0057] Experiment Example 7: Fourier Transform Infrared Spectroscopy The lyophilized gel sample was mixed with potassium bromide at a mass ratio of 1:100, ground, and compressed into tablets. The tablets were then scanned using a Fourier transform infrared spectroscopy (FTIR) instrument.

[0058] Depend on Figure 7 As can be seen, the OH stretching vibration absorption peak of the example sample shifts towards lower wavenumbers and narrows, indicating that extensive intermolecular hydrogen bonds have formed between the hydroxyl groups abundant on the surface of the cellulose nanocrystals and the hydroxyl groups on the agar molecular chains. The peak located at 1640 cm⁻¹ in the example sample...-1 The nearby OH bending vibration peaks showed a decrease in intensity and a change in peak shape, indicating that the more ordered hydrogen bond network in the gel of the example replaced the relatively loose hydration structure in the comparative example, and the water molecules were more tightly bound in the network.

[0059] Experimental Example 8: Analysis of the Thermal Properties of Gel Under nitrogen protection, the temperature was increased from 25℃ to 200℃ at a rate of 10℃ / min, and the DSC curve was recorded.

[0060] Depend on Figure 8 As can be seen, the endothermic enthalpy and peak intensity of the sample in the examples both increased significantly with the increase of cellulose nanocrystal addition, the endothermic valley in the intermediate temperature region deepened, and the trend of heat flow returning to the baseline after the main endothermic peak was gradually delayed. This indicates that the introduction of cellulose nanocrystals makes the gel network structure more compact and stable, increases the energy required for thermal transformation, slows down network relaxation, and improves thermal stability.

[0061] Experimental Example 9 Thermal Stability Analysis Under a nitrogen atmosphere, the temperature was increased from room temperature to 600℃ at a rate of 10℃ / min, and the TGA curve was recorded. The first derivative of the TGA curve was then processed to obtain the DTG curve.

[0062] Depend on Figure 9 and 10 It is evident that the main degradation stage of the gel in the example is advanced, and the peak temperature of DTG shifts towards lower temperatures. However, the residual weight rate in the high-temperature region is higher, indicating that the introduction of cellulose nanocrystals alters the thermal degradation process of the agar gel and has a beneficial effect on improving the structural stability and residual carbon retention capacity in the high-temperature stage.

[0063] Experimental Example 10: Determination of Gel Sphere Hardness The hardness of the gel spheres was determined using a texture analyzer, and the maximum compressive force was used to characterize the ability of the gel spheres to resist compressive deformation.

[0064] Depend on Figure 11 It can be seen that, under the same test conditions, the maximum compressive force that the gel spheres of Example 2 can withstand is higher than that of the comparative example, indicating that the introduction of cellulose nanocrystals enhances the compressive deformation resistance of the gel sphere shell. This demonstrates that the gel sphere encapsulation system constructed in this invention has higher mechanical strength, which is beneficial for maintaining structural integrity during processing and storage.

[0065] Experiment Example 11: Oxidative Stability Experiment Antarctic krill oil and the resulting core-shell gel spheres were subjected to accelerated oxidation storage at 45°C for 14 days, and the peroxide value and thiobarbituric acid value of the samples were measured during the storage process.

[0066] pass Figure 12 and 13It can be seen that the peroxide value and thiobarbituric acid value of the gel spheres in the example increased less rapidly than those in the comparative example, and the overall upward trend was more gradual. This indicates that the agar composite gel shell reinforced with cellulose nanocrystals can, to some extent, delay the accumulation of primary and secondary oxidation products of Antarctic krill oil, thereby improving the oxidative stability of the encapsulated Antarctic krill oil during storage.

Claims

1. A core-shell confined Antarctic krill oil composite gel sphere, characterized in that, It is composed of cellulose nanocrystals, agar, and Antarctic krill oil; including an Antarctic krill oil core layer and an agar-cellulose nanocrystal composite gel shell layer covering the outside of the Antarctic krill oil core layer.

2. The method for preparing the core-shell confined Antarctic krill oil composite gel spheres according to claim 1, characterized in that, Based on the thermoreversible agar gel network, cellulose nanocrystals are introduced. By leveraging their rigid framework reinforcement and hydrogen bonding with agar molecular chains, the processes of gel segment association, network densification, and shell reinforcement are regulated to construct a composite gel shell with good thermal processing adaptability, strong spatial continuity, and high mechanical load-bearing capacity. This gel shell is formed by coaxial dripping and low-temperature gelation, realizing the steady-state transformation of Antarctic krill oil from a fluid, easily oxidized oil to a core-shell confined gel sphere.

3. A method for preparing a core-shell confined Antarctic krill oil composite gel sphere, characterized in that, Includes the following steps: (1) Disperse cellulose nanocrystals in water and sonicate them with a pulse probe at a power of 200~300W for 25min to prepare a cellulose nanocrystal dispersion. (2) Add agar to the cellulose nanocrystal dispersion to make the concentration of agar 2.0%~3.0%, hydrate for 5~15 min, heat to 95℃ and hold at this temperature for 15 min to obtain an agar-cellulose nanocrystal composite hot solution, which is used as a wall material adhesive; (3) Transfer the wall material adhesive to the wall material storage unit of the coaxial dripping device and keep it at 70~80°C to maintain the hot solution state; (4) Add Antarctic krill oil as the core liquid to the core material storage unit of the coaxial dripping device; (5) The wall material adhesive and core liquid are dripped through a coaxial double-hole nozzle with an inner needle diameter of 1.2 mm and an outer needle inner diameter of 2 mm to form core-shell droplets; (6) Drop the core-shell liquid into a medium-chain triglyceride at 5-15°C to form a core-shell wet gel ball; (7) The obtained core-shell wet gel balls were dried in a drum for 3 hours to obtain core-shell confined Antarctic krill oil composite gel balls.

4. The preparation method according to claim 3, characterized in that, In step (1), the ultrasonic power of the pulse probe for ultrasonic processing is 250W; the processing method is ultrasonic for 2 seconds, intermittent for 2 seconds cycle.

5. The preparation method according to claim 3, characterized in that, In step (1), the concentration of the cellulose nanocrystal dispersion is 0.25%~1.0%.

6. The preparation method according to claim 3, characterized in that, In step (2), the concentration of agar in the agar-cellulose nanocrystal composite hot solution is 2.5%; the stirring hydration time is 10 min.

7. The preparation method according to claim 3, characterized in that, In step (3), the insulation temperature of the wall material adhesive in the wall material storage unit is 75°C.

8. The preparation method according to claim 3, characterized in that, In step (5), the speed of the wall material adhesive delivery pump is 200 r / min and the speed of the core liquid delivery pump is 180 r / min during the dripping process.

9. The preparation method according to claim 3, characterized in that, In step (6), the temperature of the medium-chain triglyceride is 10°C.

10. The preparation method according to claim 3, characterized in that, In step (7), the temperature of the drum drying is 25°C.

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