Stable high-internal-phase Pickering emulsion gel only based on ellagic acid particles and 3D printing application of stable high-internal-phase Pickering emulsion gel

Abstract

The invention belongs to the technical field of emulsion gel preparation, and discloses stable high-internal-phase Pickering emulsion gel only based on ellagic acid particles and 3D printing application of the stable high-internal-phase Pickering emulsion gel. The preparation method of the emulsion set comprises the following steps: dispersing ellagic acid powder in water, performing ultrasonic treatment to obtain a suspension, then centrifuging the suspension, collecting supernate, and drying to obtain ellagic acid nanoparticles; weighing the ellagic acid nano-particles, putting the ellagic acid nano-particles into a non-polar solvent, and mixing to obtain an oil dispersion liquid of the ellagic acid nano-particles; and mixing the prepared oil dispersion liquid with water, and carrying out high-speed shearing emulsification to obtain the stable high-internal-phase Pickering emulsion gel only based on ellagic acid particles. According to the invention, the single ellagic acid nanoparticles are used as a stable medium for the first time, so that the process complexity and safety risk caused by multi-component compounding are avoided, and the simplification and greenization of system components are realized.

Description

Technical Field

[0001] This invention belongs to the field of emulsion gel preparation technology, and specifically relates to a high internal phase Pickering emulsion gel stabilized solely by ellagic acid particles and its 3D printing application. Background Technology

[0002] High internal phase emulsions (HIPEs), with an internal phase volume fraction exceeding 74%, have broad application prospects in food, pharmaceuticals, and materials. Among them, high internal phase Pickering emulsions achieve stability by replacing traditional small molecule surfactants with solid particles adsorbed at the oil-water interface, possessing advantages such as good biocompatibility, no risk of chemical residues, and strong interfacial mechanical stability, making them a current research hotspot.

[0003] In existing technologies, the solid particles of stable high-internal-phase Pickering emulsion gels are mainly classified into three categories: polysaccharides, proteins, and complexes. Polysaccharide particles, such as cellulose nanocrystals and chitin nanocrystals, while possessing controllable structure, face significant challenges in adjusting wettability. Protein particles, such as gluten and whey protein, exhibit excellent emulsifying properties but are highly sensitive to environmental factors, easily becoming unstable due to pH and ionic strength. Complex particles are mostly protein-polysaccharide, protein-polyphenol, or protein-polysaccharide-lipid combinations. While they can overcome the shortcomings of single particles, they suffer from complex preparation processes, unclear nutritional interactions between components, insufficient safety assessments, and ambiguous stabilization mechanisms.

[0004] Ellagic acid, a natural polyphenol, is widely found in plants such as pomegranate, grape, and strawberry. It possesses a unique rigid tetracyclic structure, exhibiting good resistance to oxidation and temperature, and possesses various biological activities including antioxidant, antibacterial, and antitumor effects. However, raw ellagic acid particles are too large, have poor wettability (being hydrophobic), and insufficient interfacial coverage, making them unsuitable for direct use as stabilizing particles in the construction of high internal-phase Pickering emulsion gels. Recent studies have used protein-ellagic acid complexes as stabilizers for high internal-phase Pickering emulsion gels and Pickering emulsions. Currently, there are no reports on technologies utilizing single ellagic acid particles to achieve stability in high internal-phase Pickering emulsion gels. Therefore, how to modify ellagic acid to meet the stability requirements of high internal-phase Pickering emulsion gels has become an urgent technical problem to be solved. Summary of the Invention

[0005] To address the shortcomings of existing high internal phase Pickering emulsion gel stabilized particles, such as complex composition, cumbersome preparation, and unclear safety, the primary objective of this invention is to provide a method for preparing high internal phase Pickering emulsion gels stabilized solely by ellagic acid particles. This method achieves the integrated construction of a "stability-functionality-green" emulsion system, simplifies the preparation process, and improves product safety and functionality.

[0006] Another objective of this invention is to provide a high internal phase Pickering emulsion gel prepared by the above method that is stable solely based on ellagic acid particles.

[0007] Another object of the present invention is to provide the application of the above-mentioned high internal phase Pickering emulsion gel based solely on ellagic acid particle stability.

[0008] The objective of this invention is achieved through the following solution: A method for preparing a high internal phase Pickering emulsion gel stabilized solely by ellagic acid particles includes the following steps: Step 1: Disperse ellagic acid powder in water, sonicate to obtain a suspension, then centrifuge the suspension, collect the supernatant and dry it to obtain ellagic acid nanoparticles (EA NPs). Step 2: Weigh the above ellagic acid nanoparticles and place them in the oil phase, then mix to obtain an oil dispersion of ellagic acid nanoparticles; Step 3: Mix the prepared oil dispersion with water and emulsify by high-speed shearing to obtain a high internal phase Pickering emulsion gel that is stable only based on ellagic acid particles.

[0009] The amount of ellagic acid powder and water used in step one is such that the concentration of ellagic acid in the resulting mixture is 1-5% (this is the ratio of solid to water, with solid in kilograms and water in liters). The ultrasonic treatment mentioned in step one refers to running at a temperature of 25-55℃ with an ultrasonic power of 100-1000W and a frequency of 20-40Hz for 10-80 minutes.

[0010] The centrifugation mentioned in step one refers to centrifugation at 4000~8000 rpm for 10-20 minutes.

[0011] The drying process described in step one is preferably freeze drying.

[0012] The oil phase mentioned in step two is at least one of soybean oil, corn oil, rapeseed oil, n-hexane, and dodecane, preferably soybean oil.

[0013] The amount of ellagic acid nanoparticles and oil phase used in step two is such that the concentration of ellagic acid nanoparticles in the resulting oil dispersion is 1-5% (this is the ratio of solid to oil, with solid in kilograms and oil in liters).

[0014] The volume of the oil dispersion mentioned in step three accounts for 74% to 83% of the total volume of the oil dispersion and water; The high-speed shear emulsification mentioned in step three refers to shear emulsification for 15s to 120s at a shear rate of 7000~15000rpm, preferably emulsification for 120s at a shear rate of 13200rpm.

[0015] A high internal phase Pickering emulsion gel, prepared by the above method, is stabilized solely by ellagic acid particles. The resulting high internal phase Pickering emulsion gel has an internal phase (i.e., oil phase) volume fraction greater than or equal to 74%.

[0016] The aforementioned high internal phase Pickering emulsion gel, stabilized solely by ellagic acid particles, can be used as a base material for 3D printing (such as food) or a loading material for nutrients. The 3D printing process specifically includes the following steps: filling the high internal phase Pickering emulsion gel, stabilized solely by ellagic acid particles, into the syringe of a 3D printer, and then performing 3D printing.

[0017] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. Pioneering single polyphenol stabilization system: Breaking through the limitations of existing technologies that rely on protein, polysaccharide or complex particles, this system is the first to use single ellagic acid nanoparticles as a stabilizing medium, avoiding the process complexity and safety risks brought about by multi-component complexes, and achieving a single component and green system.

[0018] 2. Excellent stability: Ellagic acid nanoparticles modified by ultrasonic self-assembly have suitable size and adjustable wettability, and can stabilize emulsion gels with an internal phase volume fraction of up to 83%.

[0019] 3. Synergistic effect of function and stability: Ellagic acid itself has antioxidant and antibacterial biological activities, which enables the emulsion gel to have both stable carrier function and biological activity.

[0020] 4. Simple and controllable process: Nanoparticles are prepared by ultrasonic self-assembly, which does not require complex chemical modification. The preparation process has low energy consumption, high repeatability, and is easy to scale up for industrial production. Attached Figure Description

[0021] Figure 1 Comparison of ellagic acid particle size before and after ultrasonic treatment.

[0022] Figure 2 This study compares the antioxidant properties of ellagic acid before and after ultrasonic treatment.

[0023] Figure 3The images show the appearance of the EANPs-stable high internal phase Pickering emulsion gel in Example 1 before and after 120 days of storage.

[0024] Figure 4 The images show the microstructures of the EANPs-stable high internal phase Pickering emulsion gel in Example 1 before and after 120 days of storage.

[0025] Figure 5 The image shows the shear viscosity and frequency sweep of the EANPs-stabilized high internal phase Pickering emulsion in Example 1.

[0026] Figure 6 The image shows the 3D printed appearance of Pickering emulsion gels with different particle concentrations in Example 1 (using a fish bone as a model).

[0027] Figure 7 The image shows the appearance of Pickering emulsion gels with different types of oil as the oil phase in Example 2.

[0028] Figure 8 The image shows a microscopic view of Pickering emulsion gels with different types of oil as the oil phase in Example 2.

[0029] Figure 9 The rheological diagrams are of Pickering emulsion gels with different types of oil as the oil phase in Example 2.

[0030] Figure 10 The image shows a 3D printed image of a Pickering emulsion gel with different types of oil as the oil phase in Example 2 (using a fishbone as a model).

[0031] Figure 11 The image shows the appearance of Pickering emulsion gels with different oil phase ratios in Example 3.

[0032] Figure 12 Microscopic images of Pickering emulsion gels with different oil phase ratios in Example 3.

[0033] Figure 13 The rheological diagrams are of Pickering emulsion gels with different oil phase ratios in Example 3.

[0034] Figure 14 The image shows a 3D printed image of Pickering emulsion gels with different oil phase ratios in Example 3 (using a fishbone as a model). Detailed Implementation

[0035] The present invention will be further described in detail below with reference to embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0036] Unless otherwise specified, all reagents used in the examples are commercially available.

[0037] Example 1—Investigating the effect of different nanoparticle concentrations on emulsion gel formation This embodiment uses ellagic acid nanoparticles to prepare Pickering emulsion gels. The concentration (kg / L) of ellagic acid nanoparticles in the oil phase was adjusted to 1%, 2%, 3%, 4%, and 5% as variables for testing. This embodiment includes the following steps: Step 1: Disperse ellagic acid powder in deionized water until the ellagic acid concentration reaches 2% (kg / L). Sonicate the solution at 45°C using an ultrasonic cleaner with 100W ultrasonic power and 40Hz frequency for 20 minutes, then sonicate at 25°C using an ultrasonic disruptor with 450W ultrasonic power and 20Hz frequency for 20 minutes. Centrifuge the resulting suspension at 4000 rpm for 16 minutes, and collect the supernatant as EA nanoparticles (EA NPs). Freeze-dry the EA NPs powder under vacuum conditions.

[0038] Step 2: The particle size and potential of the particles were measured using a nanoparticle size potentiometer. Particle size parameters were set as follows: ellagic acid refractive index 1.65, deionized water dispersant with a refractive index of 1.333, and absorbance 0.01. Three parallel groups were set up for each sample, and measurements were taken after equilibration for 2 minutes.

[0039] Step 3: Prepare a 0.1 mM DPPH solution and a 0.1 mg / mL EA aqueous solution; take 180 μL of DPPH solution and mix thoroughly with 20 μL of EA aqueous solution (or an EA NPs dispersion of equal concentration), and react at room temperature in the dark for 30 min; after the reaction, measure the change in absorbance of the system, and calculate the DPPH free radical scavenging rate using the following formula: Clearance rate (%) = [A 空白 -A 样品 -A 样品空白 ]×100, where A 空白 A represents the absorbance of a mixture of DPPH solution and deionized water. 样品 A represents the absorbance of the sample (EA or EA NPs) after mixing with the DPPH solution. 样品空白 The absorbance is the result of mixing the sample with deionized water.

[0040] Prepare ABTS⁺ working solution, EA, and EA NPs aqueous solution with a concentration of 0.05 mg / mL, respectively; take 190 μL of ABTS⁺ working solution and mix it thoroughly with 10 μL of EA aqueous solution (or EA NPs dispersion of equal concentration), and react at room temperature in the dark for 7 min; after the reaction, measure the change in absorbance (or fluorescence intensity) of the system, and calculate the ABTS⁺ free radical scavenging rate by referring to the above DPPH free radical scavenging rate formula (replacing the corresponding absorbance / fluorescence intensity parameters).

[0041] Step 4: Weigh the above-mentioned freeze-dried ellagic acid nanoparticles and place them in soybean oil. Vortex mix for 3 minutes to obtain soybean oil dispersions of ellagic acid nanoparticles with different particle concentrations (c=1%, 2%, 3%, 4%, 5%). Similarly, weigh the untreated raw ellagic acid and add it to soybean oil to prepare raw ellagic acid soybean oil dispersions with the same concentrations (c=1%, 2%, 3%, 4%, 5%) as a control. The concentrations are solid mass / liquid volume ratios, with solids measured in kilograms and liquids in liters.

[0042] Step 5: Mix the prepared oil dispersions of various concentrations with deionized water at a volume ratio of 4:1, and emulsify for 120 s using a high-speed shear machine at a shearing speed of 13200 rpm to obtain a stable emulsion gel.

[0043] Step Six: The five Pickering emulsion gel samples obtained in Step Three are uniformly filled into the syringe of the food 3D printer and printed at 25°C and 20mm / s through a 0.84mm nozzle (using a fishbone as a model). After standing for 0.5 hours, the appearance of the model is observed.

[0044] 1. Test on the effects of ultrasonic treatment on particle size and antioxidant properties: The particle size distribution results of the original EA and EA NPs are as follows: Figure 1 As shown, the original EA particles had a size of 550±50 nm and a polydispersity index (PDI) of 0.85±0.06, indicating uneven particle size distribution. After ultrasonic assembly, the particle size of EANPs decreased to 105±5 nm, with a polydispersity index of 0.18±0.03 and a PDI value less than 0.2, indicating good size uniformity of EA NPs, meeting the characterization standard for nanoparticles (particle size <1000 nm). This result confirms that the ultrasonic assembly method can effectively further reduce the particle size of EA particles, and the treated particles have uniform size, laying the foundation for subsequent performance improvement.

[0045] DPPH free radical scavenging rate test results are as follows Figure 2As shown, the DPPH radical scavenging rate of the original EA was 28.3 ± 2.8%, while the scavenging rate of EA NPs was 59.1 ± 3.5%, significantly higher than that of the original EA (p < 0.05). Meanwhile, ABTS... + Free radical scavenging rate test results show that the original EA's ABTS + The free radical scavenging rate was 46.5±4.2%, while that of EA NPs was 79.2±2.1%, significantly higher than that of the original EA (p<0.05). Both testing methods confirmed that the antioxidant activity of EA NPs was superior to that of the original EA. The main reason for the improved antioxidant activity of EA NPs is the increased specific surface area due to the reduced particle size, resulting in a greater number of exposed phenolic hydroxyl groups on the surface. This significantly increases the probability of contact between phenolic hydroxyl groups and free radicals, thereby enhancing the free radical scavenging ability. This indicates that ultrasonic nano-sizing not only did not destroy the antioxidant activity of EA, but also significantly improved its antioxidant capacity.

[0046] 2. Appearance and microstructure testing: like Figure 3 and 4 As shown, this paper presents the appearance and microscopic images of Pickering emulsion gels prepared from soybean oil dispersions containing ellagic acid nanoparticles (EANPs) at concentrations of 1%, 2%, 3%, 4%, and 5% before and after 120 days of storage. The results indicate that the emulsion gels at all concentrations exhibit a uniform brown appearance and do not flow when the bottle is inverted, indicating the initial formation of an emulsion gel. Furthermore, no significant demulsification was observed after 120 days of storage, demonstrating the good stability of the formed emulsion gel. Figure 4 The microstructure showed uniform droplets, and the droplet size tended to decrease with increasing particle concentration, indicating that increased particle concentration facilitates the formation of smaller droplets. Similarly, the microstructure of the emulsion did not change significantly after 120 days of storage, demonstrating the high stability of the emulsion gel. Figure 4 The image also shows a microscopic image of an emulsion gel prepared with untreated ellagic acid after 0 days of storage. The image shows that untreated ellagic acid has poor emulsifying properties and cannot form a stable emulsion gel in vegetable oil. In contrast, the treated ellagic acid particles have a smaller particle size and improved surface properties, resulting in improved emulsifying performance of nanoparticles. The emulsion formed has uniform droplet size under the microscope, and the droplets do not deform after 120 days of storage, indicating that the high internal phase emulsion gel of nano-ellagic acid has good stability.

[0047] 3. Viscosity as a function of shear rate test: like Figure 5As shown, the viscosity of Pickering emulsion gels prepared from soybean oil dispersions containing ellagic acid nanoparticles (EANPs) at concentrations of 1%, 2%, 3%, 4%, and 5% is tested as a function of shear rate. The results indicate that all five Pickering emulsion gels exhibit similar viscosity trends, exhibiting typical shear thinning. Furthermore, the viscosity of the Pickering emulsion gel increases with increasing particle concentration. Above 35 r / s, the viscosity change remains relatively stable with increasing shear rate, demonstrating that this particle-stable Pickering emulsion gel maintains relatively stable processing performance even with varying extrusion rates in food 3D printing.

[0048] 4. Testing of energy storage modulus (G') and loss modulus (G”) as a function of frequency: like Figure 5 As shown, this paper illustrates the relationship between storage modulus / frequency and loss modulus / frequency for five Pickering emulsion gels prepared from soybean oil dispersions containing ellagic acid nanoparticles at concentrations of 1%, 2%, 3%, 4%, and 5%. Throughout the frequency range, the storage modulus of all samples is nearly an order of magnitude higher than the loss modulus, indicating that each sample can form a strong gel network structure and exhibit good solid viscoelasticity. Furthermore, the storage modulus is almost independent of frequency throughout the 0.1–8 Hz range, with a decrease occurring in the 8–10 Hz range. This demonstrates the typical stability of the gel network within a reasonable vibration frequency range, as seen in gel emulsions, and exhibits a thinning trend at high frequencies, suggesting 3D printing potential. Additionally, with increasing particle concentration, both the storage modulus and loss modulus of each Pickering emulsion gel increase compared to the previous test concentration.

[0049] 5. 3D printing test: The five Pickering emulsion gel samples obtained in step three were uniformly filled into the syringe of a food 3D printer and printed at 25°C and 20 mm / s through a 0.84 mm nozzle (using a fish bone as a model). After standing for 0.5 hours, the appearance of the model was observed.

[0050] Test results: such as Figure 6 As shown, five Pickering emulsion gels with particle concentrations of 1%, 2%, 3%, 4%, and 5% were used to print fishbone models using a 3D printer. From the appearance, it can be observed that, except for the 1% particle concentration emulsion gel which has a blurred shape and some water seepage, the other particle concentration emulsion gels have very clear outlines and no water seepage, indicating good printing characteristics and storage stability. Considering all factors, a particle concentration of 4% was selected as the research condition for subsequent examples.

[0051] Example 2—Investigating the effect of different oil phase types on emulsion gel formation This embodiment uses ellagic acid nanoparticles to prepare Pickering emulsion gels. The experiment was conducted by dispersing ellagic acid nanoparticles at a concentration of 4% in five oil phases: soybean oil, corn oil, rapeseed oil, and hexane and dodecane. The embodiment includes the following steps: Step 1: Disperse ellagic acid powder in deionized water until the ellagic acid concentration reaches 2% (kg / L). Sonicate the solution at 45°C using an ultrasonic cleaner with 100W ultrasonic power and 40Hz frequency for 20 minutes, then sonicate at 25°C using an ultrasonic disruptor with 450W ultrasonic power and 20Hz frequency for 20 minutes. Centrifuge the resulting suspension at 4000 rpm for 16 minutes, and collect the supernatant as EA nanoparticles (EA NPs). Freeze-dry the EA NPs powder under vacuum conditions.

[0052] Step 2: Weigh the above freeze-dried ellagic acid nanoparticles and place them in soybean oil, corn oil, rapeseed oil, n-hexane and dodecane respectively. Vortex mix for 3 min to finally obtain different oil dispersions of ellagic acid nanoparticles with a particle concentration of 4% (kg / L).

[0053] Step 3: Mix the prepared oil dispersions of various concentrations with deionized water at a volume ratio of 4:1, and emulsify for 120 s using a high-speed shear machine at a shearing speed of 13200 rpm to obtain a stable emulsion gel.

[0054] Step 4: The gel sample obtained in Step 3 is uniformly filled into the syringe of the food 3D printer to complete the 3D printing.

[0055] 1. Appearance and microstructure testing: like Figure 7 and 8 As shown, this paper presents the appearance and microscopic images of Pickering emulsion gels prepared by dispersing ellagic acid nanoparticles (EANPs) at a concentration of 4% in different oil phases (soybean oil, corn oil, rapeseed oil, n-hexane, and dodecane). The results show that the emulsion gels in different oil phases exhibit a uniform light yellow appearance (the emulsion gel with rapeseed oil as the oil phase is slightly darker in color), and do not flow when the bottle is inverted, indicating the initial formation of an emulsion gel. Figure 8 The microstructure exhibits uniform droplets, and the droplet size does not change significantly with the change of oil phase, indicating that this emulsion gel preparation method is applicable to different oil phases.

[0056] 2. Viscosity as a function of shear rate test: like Figure 9As shown, this paper presents the results of viscosity variation tests as a function of shear rate for Pickering emulsion gels prepared by dispersing ellagic acid nanoparticles (EANPs) in different oil phases. The results indicate that all five Pickering emulsion gels exhibit similar viscosity trends, namely typical shear thinning. At the same frequency, the viscosity of the emulsion gel with vegetable oils (soybean oil, corn oil, and rapeseed oil) as the oil phase is significantly higher than that with organic solvents (n-hexane and dodecane) as the oil phase. Above 35 r / s, the viscosity change is relatively stable with increasing shear rate, demonstrating that the Pickering emulsion gels with different oil phases maintain relatively stable processing performance when subjected to varying extrusion rates in food 3D printing.

[0057] 3. Testing of energy storage modulus (G') and loss modulus (G”) as a function of frequency: like Figure 9 As shown, this paper illustrates the relationship between storage modulus / frequency and loss modulus / frequency for five Pickering emulsion gels prepared by dispersing ellagic acid nanoparticles in different oil phases. Throughout the frequency range, the storage modulus of all samples is nearly an order of magnitude higher than the loss modulus, indicating that each sample can form a strong gel network structure and exhibit good solid viscoelasticity. Furthermore, the storage modulus is almost independent of frequency throughout the 0.1-6 Hz range, with a partial decrease in storage modulus between 6-10 Hz. This reflects the typical characteristics of gel emulsions in maintaining gel network stability within a reasonable vibration frequency range, and shows a thinning trend at high frequencies, indicating 3D printing potential. Overall, the emulsion gels with vegetable oil as the oil phase have higher storage modulus and loss modulus than those with organic solvent as the oil phase. Specifically, at any frequency, the order of G' from largest to smallest is: soybean oil > rapeseed oil > corn oil > dodecane > n-hexane.

[0058] 4. 3D printing test: The five Pickering emulsion gel samples obtained in step three were uniformly filled into the syringe of a food 3D printer and printed at 25°C and 20 mm / s through a 0.84 mm nozzle (using a fish bone as a model). After standing for 0.5 hours, the appearance of the model was observed.

[0059] Test results: such as Figure 10As shown, this paper presents five Pickering emulsion gels prepared from different oil phases—soybean oil, corn oil, rapeseed oil, n-hexane, and dodecane—and their fishbone-shaped finished models printed using a 3D printer. From the appearance, it can be observed that, except for the n-hexane emulsion gel which exhibits some collapse, the other oil-phase emulsion gels have very clear outlines and show no water seepage, indicating good printing characteristics and storage stability. Considering all factors, soybean oil was selected as the oil phase for subsequent examples.

[0060] Example 3—Investigating the effect of different oil phase ratios on emulsion gel formation In this embodiment, Pickering emulsion gels were prepared using ellagic acid nanoparticles. The oil phase ratio (i.e., the ratio of oil phase volume to the total volume of (oil phase + water phase)) was adjusted to 0.74, 0.8, 0.81, 0.82, and 0.83 as variables for testing. This embodiment includes the following steps: Step 1: Disperse ellagic acid powder in deionized water until the ellagic acid concentration reaches 2% (kg / L). Sonicate the solution at 45°C using an ultrasonic cleaner with 100W ultrasonic power and 40Hz frequency for 20 minutes, then sonicate at 25°C using an ultrasonic disruptor with 450W ultrasonic power and 20Hz frequency for 20 minutes. Centrifuge the resulting suspension at 4000 rpm for 16 minutes, and collect the supernatant as EA nanoparticles (EA NPs). Freeze-dry the EA NPs powder under vacuum conditions.

[0061] Step 2: Weigh the above freeze-dried ellagic acid nanoparticles and place them in soybean oil. Vortex mix for 3 minutes to finally obtain a soybean oil dispersion of ellagic acid nanoparticles with a particle concentration of 4% (kg / L).

[0062] Step 3: Mix the prepared oil dispersions of various concentrations with deionized water at volume ratios of 2.85:1, 4:1, 4.26:1, 4.56:1, and 4.88:1, and emulsify them for 120 s using a high-speed shear machine at a shearing speed of 13200 rpm to obtain stable emulsion gels with oil phase ratios of 0.74, 0.80, 0.81, 0.82, and 0.83, respectively.

[0063] Step 4: The five Pickering emulsion gel samples obtained in Step 3 are uniformly filled into the syringe of the food 3D printer and printed at 25°C and 20mm / s through a 0.84mm nozzle (using a fishbone as a model). After standing for 0.5 hours, the appearance of the model is observed.

[0064] 1. Appearance and microstructure testing: like Figure 11 and 12As shown, this paper presents the appearance and microscopic images of Pickering emulsion gels prepared based on a soybean oil dispersion containing 4% ellagic acid nanoparticles (EANPs) and different oil phase ratios (0.74, 0.80, 0.81, 0.82, 0.83). The results indicate that the highest oil phase ratio for forming emulsion gels is 0.83, and all emulsion gels exhibit a uniform brown appearance and do not flow when the bottle is inverted, indicating the initial formation of emulsion gels. Figure 12 The microstructure exhibits uniform droplets, with the droplet size of the emulsion gel at an oil phase ratio of 0.74 being slightly larger than that at other oil phase ratios. Furthermore, the droplet size did not change significantly with increasing particle concentration.

[0065] 2. Viscosity as a function of shear rate test: like Figure 13 As shown, the viscosity of Pickering emulsion gels prepared based on soybean oil dispersions containing 4% ellagic acid nanoparticles (EANPs) and different oil phase ratios (0.74, 0.80, 0.81, 0.82, 0.83) as a function of shear rate was tested. The results showed that all five Pickering emulsion gels exhibited similar trends, namely typical shear thinning. Furthermore, with increasing oil phase ratio, the viscosity of the Pickering emulsion gels initially increased and then decreased. Above 35 r / s, the viscosity change remained relatively stable with increasing shear rate, demonstrating that these different oil phase ratios of Pickering emulsion gels maintain relatively stable processing performance when faced with varying extrusion rates in food 3D printing.

[0066] 3. Testing of energy storage modulus (G') and loss modulus (G”) as a function of frequency: like Figure 13 As shown, the storage modulus / frequency and loss modulus / frequency relationships of five Pickering emulsion gels prepared based on a 4% ellagic acid nanoparticle dispersion and different oil phase ratios (0.74, 0.80, 0.81, 0.82, 0.83) are illustrated. Throughout the frequency range, the storage modulus of all samples is nearly an order of magnitude higher than the loss modulus, indicating that each sample can form a strong gel network structure and exhibit good solid viscoelasticity. Furthermore, the storage modulus is almost independent of frequency throughout the 0.1-8 Hz range, demonstrating the typical ability of a gel emulsion to maintain gel network stability within a reasonable vibration frequency range, indicating 3D printing potential. Additionally, with increasing oil phase ratio, the storage modulus and loss modulus of each Pickering emulsion gel show a trend of first increasing and then decreasing, with the emulsion gel with an oil phase ratio of 0.82 exhibiting the strongest modulus.

[0067] 4. 3D printing test: The five Pickering emulsion gel samples obtained in step three were uniformly filled into the syringe of a food 3D printer and printed at 25°C and 20 mm / s through a 0.84 mm nozzle (using a fish bone as a model). After standing for 0.5 hours, the appearance of the model was observed.

[0068] Test results: such as Figure 14 As shown, it displays five Pickering emulsion gels with oil phase ratios of 0.74, 0.80, 0.81, 0.82, and 0.83, which were 3D printed with fishbone models. The appearance reveals that the emulsion gels have very clear outlines and show no water seepage, indicating good printing properties and storage stability.

[0069] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A process for the preparation of a high internal phase Pickering emulsion gel stabilized by ellagic acid particles only, characterized in that The method comprises the following steps: Step 1: dispersing tannic acid powder in water, ultrasonic treatment to obtain a suspension, then centrifuging the suspension, collecting the supernatant and drying to obtain tannic acid nanoparticles; Step 2: weighing the tannic acid nanoparticles in the oil phase to obtain an oil dispersion of tannic acid nanoparticles; Step 3: mixing the prepared oil dispersion with water, high-speed shearing emulsification, to obtain a high internal phase Pickering emulsion gel stabilized by tannic acid particles.

2. The method for preparing the high internal phase Pickering emulsion gel stabilized by tannic acid particles according to claim 1, wherein: the amount of tannic acid powder and water in step 1 satisfies that the concentration of tannic acid in the obtained mixture is 1-5%, wherein the concentration is the ratio of solid to water, the unit of solid is kg, and the unit of water is L.

3. The method for preparing the high internal phase Pickering emulsion gel stabilized by tannic acid particles according to claim 1, wherein: the ultrasonic treatment in step 1 refers to ultrasonic treatment at a temperature of 25-55℃, an ultrasonic power of 100-1000W, and a frequency of 20-40Hz for 10-80 minutes; The centrifugation in step 1 refers to centrifugation at 4000-8000 rpm for 10-20 minutes.

4. The method for preparing the high internal phase Pickering emulsion gel stabilized by tannic acid particles according to claim 1, wherein: the oil phase in step 2 is at least one of soybean oil, corn oil, rapeseed oil, n-hexane, and dodecane, and is preferably soybean oil.

5. The method for preparing the high internal phase Pickering emulsion gel stabilized by tannic acid particles according to claim 1, wherein: the amount of tannic acid nanoparticles and oil phase in step 2 satisfies that the concentration of tannic acid nanoparticles in the obtained oil dispersion is 1-5%, wherein the concentration is the ratio of solid to oil, the unit of solid is kg, and the unit of oil is L.

6. The method for preparing the high internal phase Pickering emulsion gel stabilized by tannic acid particles according to claim 1, wherein: the volume of the oil dispersion in step 3 accounts for 74%-83% of the total volume of the oil dispersion and water.

7. The method for preparing the high internal phase Pickering emulsion gel stabilized by tannic acid particles according to claim 1, wherein: the high-speed shearing emulsification in step 3 refers to shearing emulsification at a shearing rate of 7000-15000 rpm for 15s-120s, and is preferably emulsification at a shearing speed of 13200 rpm for 120s.

8. A high internal phase Pickering emulsion gel stabilized by tannic acid particles, which is prepared by the method according to any one of claims 1-7.

9. The high internal phase Pickering emulsion gel stabilized by tannic acid particles according to claim 8, which is used as a 3D printing base material or a nutrient substance loading material. ​ ​ ​ ​ ​ ​ 10. Use of a high internal phase Pickering emulsion gel stabilized by ellagic acid particles only according to claim 9, characterized in that 3D printing specifically comprises the following steps: filling the high internal phase Pickering emulsion gel stabilized by ellagic acid particles only into a syringe of a food 3D printer, 3D printing.

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