An oil-in-water gel-based pickering emulsion, preparation method and application

Abstract

The application discloses an oil-in-water gel Pickering emulsion, a preparation method and application, and comprises the following steps: step 1, dispersing liquid oil and beeswax to obtain an oil gel; step 2, adding nanocellulose whiskers into a sodium alginate solution, and fully mixing to obtain an aqueous phase solution; wherein the mass ratio of the sodium alginate and the nanocellulose whiskers is 2-10:5; step 3, fully mixing and dispersing the oil gel in step 1 and the aqueous phase solution in step 2 to obtain the required oil-in-water gel Pickering emulsion; the oil-in-water gel Pickering emulsion obtained by adding the sodium alginate and the modified CNW as emulsifiers has a significantly improved ability of embedding and delivering curcumin, and the chemical stability and the bio-accessibility of the curcumin are improved.

Description

Technical Field

[0001] This invention relates to the field of biomaterials technology, specifically to a water-in-oil gel Pickering emulsion, its preparation method, and its application. Background Technology

[0002] Curcumin is a polyphenolic compound belonging to the diphenylheptane class, appearing as an orange-yellow crystalline powder. Studies have found that curcumin possesses functional properties such as anti-inflammatory, antioxidant, anti-tumor, free radical scavenging, and digestive system benefits. In clinical trials, curcumin demonstrated high safety, with a safe dose reaching 12g daily. However, its low solubility, poor chemical stability, and low bioavailability limit its application in the food and pharmaceutical fields. In particular, curcumin is easily degraded under acidic conditions; ingested curcumin is destroyed during gastric digestion, with only a very small amount reaching the small intestine for absorption, resulting in extremely low bioavailability and limited clinical use. Therefore, finding a method to deliver curcumin effectively is crucial. Although existing Pickering emulsions can improve curcumin encapsulation and delivery capabilities to some extent, the results are not ideal. Summary of the Invention

[0003] This invention addresses the problems existing in the prior art by providing a water-in-oil gel Pickering emulsion, its preparation method, and its application.

[0004] The technical solution adopted in this invention is:

[0005] A method for preparing an oil-in-water gel-pickering emulsion includes the following steps:

[0006] Step 1: Disperse the liquid oil and beeswax to obtain an oil gel;

[0007] Step 2: Add nanocellulose whiskers to sodium alginate solution and mix thoroughly to obtain an aqueous solution; wherein the mass ratio of sodium alginate to nanocellulose whiskers is 2-10:5.

[0008] Step 3: Thoroughly mix and disperse the oleogel from Step 1 with the aqueous solution from Step 2 to obtain the desired oil-in-water gel Pickering emulsion.

[0009] Furthermore, the nanocellulose whiskers are modified nanocellulose whiskers that have undergone hydrochloric acid desulfurization treatment.

[0010] The preparation method of modified nanocellulose whiskers is as follows:

[0011] Hydrochloric acid and nanocellulose whiskers were mixed and heated with shaking at 98–100 °C and 100 rpm for 0.5–1 h to obtain modified nanocellulose whiskers; wherein the mass ratio of hydrochloric acid to nanocellulose was 9:10.

[0012] Furthermore, after the hydrochloric acid and nanocellulose whiskers have reacted, the modified nanocellulose whiskers can be obtained by cooling, centrifuging, washing, and dialysis; the centrifugation speed is 8000 rpm and the centrifugation time is 15 min.

[0013] Furthermore, the gel preparation process in step 1 is as follows:

[0014] Add beeswax to soybean oil at a concentration of 10.0% w / v; stir at 300 rpm and 80°C for 15 minutes to obtain the desired oleogel.

[0015] Furthermore, in step 2, the aqueous solution is heated at 80°C for 15 minutes.

[0016] Furthermore, the mixing and dispersion process in step 3 is as follows:

[0017] First, homogenize for 2 minutes at an emulsifier speed of 10,000 rpm;

[0018] Then, pulse ultrasound was performed at 525W for 2 minutes.

[0019] During ultrasound, work for N seconds, pause for M seconds, and repeat the ultrasound cycle.

[0020] Furthermore, the aqueous solution in step 2 also contains NaCl, wherein the concentration of NaCl is 60 mM.

[0021] A water-in-oil gel-pickering emulsion.

[0022] An application based on an oil-in-water gel-pickering emulsion, wherein the oil-in-water gel-pickering emulsion serves as a nutrient encapsulation and delivery carrier.

[0023] Furthermore, the nutrient is curcumin.

[0024] The beneficial effects of this invention are:

[0025] The present invention significantly improves the ability of oil-in-water gel Pickering emulsion to encapsulate and deliver curcumin by adding sodium alginate and modified CNW as emulsifiers, and also improves the chemical stability and bioavailability of curcumin.

[0026] The water-in-oil gel Pickering emulsion obtained by this invention can achieve a high encapsulation rate for nutrients that are poorly soluble in both oil and water. Attached Figure Description

[0027] Figure 1 This is a schematic diagram showing the density of sulfonic acid groups on the surface of nanocellulose whiskers obtained in Examples 1-2 and Comparative Examples 1, 2, and 3 of the present invention.

[0028] Figure 2 The diagrams shown are schematic diagrams of the microstructure of the oil-in-water gel Pickering emulsions obtained in Examples 1-2 and Comparative Examples 1, 2, and 3 of this invention. a is a schematic diagram of laser confocal microscopy, and b is a schematic diagram of the emulsion particle size distribution.

[0029] Figure 3 The diagrams shown are schematic diagrams of the stability test results of the water-in-oil gel Pickering emulsions obtained in Examples 1-2 and Comparative Examples 1, 2, and 3 of the present invention. a is a macroscopic morphology diagram during storage, b is a CI test result diagram during storage, c is an optical microscope schematic diagram during storage, and d is a schematic diagram of the average particle size statistical results during storage.

[0030] Figure 4 The diagram shows the stability test results of the water-in-oil gel Pickering emulsions obtained in Examples 1, 3, and 4 and Comparative Example 4 of this invention. a is a macroscopic morphology diagram during storage, b is a CI test result diagram during storage, c is an optical microscope diagram during storage, and d is a schematic diagram of the average particle size statistics during storage.

[0031] Figure 5 This is a comparison of the encapsulation of curcumin by the oil-in-water gel Pickering emulsions obtained in Example 4 and Comparative Example 4 of the present invention. a is the encapsulation rate of curcumin, and b is the retention rate during storage.

[0032] Figure 6 The curcumin release rate during gastrointestinal digestion after curcumin was encapsulated in the oil-in-water gel Pickering emulsion obtained in Example 4 and Comparative Example 4 of this invention.

[0033] Figure 7 The bioavailability of curcumin after being encapsulated in the oil-in-water gel Pickering emulsion obtained in Example 4 and Comparative Example 4 of this invention. Detailed Implementation

[0034] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0035] A method for preparing an oil-in-water gel-pickering emulsion includes the following steps:

[0036] Step 1: Disperse liquid oil and beeswax to obtain an oil gel; add beeswax to soybean oil, wherein the concentration of beeswax is 10.0% w / v; stir at 300 rpm and 80°C for 15 minutes to melt and evenly disperse the beeswax, and the desired oil gel can be obtained.

[0037] Step 2: Add nanocellulose whiskers to sodium alginate solution, mix thoroughly to obtain an aqueous solution, and heat at 80℃ for 15 min; wherein the mass ratio of sodium alginate to nanocellulose whiskers is 2-10:5; the sodium alginate solution contains NaCl, and the concentration of NaCl is 60 mM.

[0038] The preparation process of nanocellulose whiskers is as follows:

[0039] Hydrochloric acid and nanocellulose whiskers were mixed and heated with shaking at 98–100 °C and 100 rpm for 0.5–1 h to obtain modified nanocellulose whiskers; wherein the mass ratio of hydrochloric acid to nanocellulose was 9:10.

[0040] Step 3: Thoroughly mix and disperse the oleogel from Step 1 with the aqueous solution from Step 2 to obtain the desired oil-in-water gel Pickering emulsion;

[0041] The dispersion process is as follows:

[0042] Homogenize the emulsion using an ultrafine homogenizer at 10,000 rpm for 2 minutes, then sonicate for 2 minutes using a high-intensity ultrasonic processor in pulse mode at 525W pressure and amplitude, with a 3-second pulse duration and a 3-second interval, to obtain an oil-in-water pickering emulsion. Maintain the temperature at 70–90℃ during dispersion. The volume ratio of the oil gel to the aqueous solution is 3:7.

[0043] Example 1

[0044] A method for preparing an oil-in-water gel-pickering emulsion includes the following steps:

[0045] Step 1: Add beeswax to soybean oil and stir at 300 rpm and 80°C for 15 minutes to melt and evenly disperse the beeswax, thus obtaining the desired oil gel. The concentration of beeswax in the oil gel is 10.0% w / v.

[0046] Step 2: Add nanocellulose whiskers to the sodium alginate solution and mix thoroughly to obtain an aqueous solution. The concentration of NaCl in the aqueous solution is 60 mM, the concentration of sodium alginate is 0.2% w / v, and the concentration of nanocellulose whiskers is 0.5% w / v. Heat at 80℃ for 15 min.

[0047] The preparation process of nanocellulose whiskers is as follows:

[0048] 100 mL of 5 mol / L hydrochloric acid and 100 mL of 20 mg / mL cellulose nanofibers were mixed and dispersed, and the mixture was heated in a constant-temperature shaking water bath at 99 °C and 100 rpm for 0.5 h to obtain modified cellulose nanofibers. After desulfurization, the mixture was first cooled, and then centrifuged and washed at 8000 rpm for 15 min. The supernatant was discarded to remove the hydrochloric acid, and centrifugation was repeated until the upper layer became turbid. The turbid suspension was poured into a dialysis bag with a molecular weight cutoff of 8000–14000 Da and dialyzed until the pH of the dialysate was neutral. The suspension in the dialysis bag was concentrated with polyethylene glycol 20000, and the concentrated sample suspension was collected and stored.

[0049] Step 3: Thoroughly mix and disperse the oleogel from Step 1 with the aqueous solution from Step 2 to obtain the desired oil-in-water pickering emulsion (denoted as CNW0.5 in the attached figure); the volume ratio of oleogel to aqueous solution is 3:7.

[0050] The dispersion process is as follows:

[0051] Homogenize using an ultrafine homogenizer at 10,000 rpm for 2 minutes, then sonicate using a high-intensity ultrasonic processor in pulse mode at 525W pressure and amplitude for 2 minutes, with a 3-second working time and a 3-second interval during the pulse, to obtain an oil-in-water gel Pickering emulsion. Maintain the temperature at 80℃ during dispersion.

[0052] Example 2

[0053] A method for preparing an oil-in-water gel-pickering emulsion includes the following steps:

[0054] Step 1: Add beeswax to soybean oil and stir at 300 rpm and 80°C for 15 minutes to melt and evenly disperse the beeswax, thus obtaining the desired oil gel. The concentration of beeswax in the oil gel is 10.0% w / v.

[0055] Step 2: Add nanocellulose whiskers to the sodium alginate solution and mix thoroughly to obtain an aqueous solution. The concentration of NaCl in the aqueous solution is 60 mM, the concentration of sodium alginate is 0.2% w / v, and the concentration of nanocellulose whiskers is 0.5% w / v. Heat at 80℃ for 15 min.

[0056] The preparation process of nanocellulose whiskers is as follows:

[0057] 100 mL of 5 mol / L hydrochloric acid and 100 mL of 20 mg / mL cellulose nanofibers were mixed and dispersed, and the mixture was heated in a constant-temperature shaking water bath at 99 °C and 100 rpm for 1 h to obtain modified cellulose nanofibers. After desulfurization, the mixture was first cooled, and then centrifuged and washed at 8000 rpm for 15 min. The supernatant was discarded to remove the hydrochloric acid, and centrifugation was repeated until the upper layer became turbid. The turbid suspension was poured into a dialysis bag with a molecular weight cutoff of 8000–14000 Da and dialyzed until the pH of the dialysate was neutral. The suspension in the dialysis bag was concentrated with polyethylene glycol 20000, and the concentrated sample suspension was collected and stored.

[0058] Step 3: Thoroughly mix and disperse the oleogel from Step 1 with the aqueous solution from Step 2 to obtain the desired oil-in-water pickering emulsion (represented as CNW1 in the attached figure); the volume ratio of oleogel to aqueous solution is 3:7.

[0059] The dispersion process is as follows:

[0060] Homogenize the mixture for 2 minutes at 10,000 rpm using an ultrafine homogenizer, then sonicate it for 2 minutes in pulse mode at 525 W pressure and amplitude using a high-intensity ultrasonic processor, with a 3-second working time and a 3-second interval during the pulse, to obtain an oil-in-water gel Pickering emulsion. Maintain the temperature at 70℃ during dispersion.

[0061] Example 3

[0062] A method for preparing an oil-in-water gel-pickering emulsion includes the following steps:

[0063] Step 1: Add beeswax to soybean oil and stir at 300 rpm and 80°C for 15 minutes to melt and evenly disperse the beeswax, thus obtaining the desired oil gel. The concentration of beeswax in the oil gel is 10.0% w / v.

[0064] Step 2: Add nanocellulose whiskers to the sodium alginate solution and mix thoroughly to obtain an aqueous solution. The concentration of NaCl in the aqueous solution is 60 mM, the concentration of sodium alginate is 0.5% w / v, and the concentration of nanocellulose whiskers is 0.5% w / v. Heat at 80℃ for 15 min.

[0065] The preparation process of nanocellulose whiskers is as follows:

[0066] 100 mL of 5 mol / L hydrochloric acid and 100 mL of 20 mg / mL cellulose nanofibers were mixed and dispersed, and the mixture was heated in a constant-temperature shaking water bath at 99 °C and 100 rpm for 0.5 h to obtain modified cellulose nanofibers. After desulfurization, the mixture was first cooled, and then centrifuged and washed at 8000 rpm for 15 min. The supernatant was discarded to remove the hydrochloric acid, and centrifugation was repeated until the upper layer became turbid. The turbid suspension was poured into a dialysis bag with a molecular weight cutoff of 8000–14000 Da and dialyzed until the pH of the dialysate was neutral. The suspension in the dialysis bag was concentrated with polyethylene glycol 20000, and the concentrated sample suspension was collected and stored.

[0067] Step 3: Thoroughly mix and disperse the oleogel from Step 1 with the aqueous solution from Step 2 to obtain the desired oil-in-water pickering emulsion; the volume ratio of oleogel to aqueous solution is 3:7.

[0068] The dispersion process is as follows:

[0069] Homogenize using an ultrafine homogenizer at 10,000 rpm for 2 minutes, then sonicate using a high-intensity ultrasonic processor in pulse mode at 525W pressure and amplitude for 2 minutes, with a 3-second working time and a 3-second interval during the pulse, to obtain an oil-in-water gel Pickering emulsion. Maintain the temperature at 90℃ during dispersion.

[0070] Example 4

[0071] A method for preparing an oil-in-water gel-pickering emulsion includes the following steps:

[0072] Step 1: Add beeswax to soybean oil and stir at 300 rpm and 80°C for 15 minutes to melt and evenly disperse the beeswax, thus obtaining the desired oil gel. The concentration of beeswax in the oil gel is 10.0% w / v.

[0073] Step 2: Add nanocellulose whiskers to the sodium alginate solution and mix thoroughly to obtain an aqueous solution. The concentration of NaCl in the aqueous solution is 60 mM, the concentration of sodium alginate is 1.0% w / v, and the concentration of nanocellulose whiskers is 0.5% w / v. Heat at 80℃ for 15 min.

[0074] The preparation process of nanocellulose whiskers is as follows:

[0075] 100 mL of 5 mol / L hydrochloric acid and 100 mL of 20 mg / mL cellulose nanofibers were mixed and dispersed, and the mixture was heated in a constant-temperature shaking water bath at 99 °C and 100 rpm for 0.5 h to obtain modified cellulose nanofibers. After desulfurization, the mixture was first cooled, and then centrifuged and washed at 8000 rpm for 15 min. The supernatant was discarded to remove the hydrochloric acid, and centrifugation was repeated until the upper layer became turbid. The turbid suspension was poured into a dialysis bag with a molecular weight cutoff of 8000–14000 Da and dialyzed until the pH of the dialysate was neutral. The suspension in the dialysis bag was concentrated with polyethylene glycol 20000, and the concentrated sample suspension was collected and stored.

[0076] Step 3: Thoroughly mix and disperse the oleogel from Step 1 with the aqueous solution from Step 2 to obtain the desired oil-in-water pickering emulsion; the volume ratio of oleogel to aqueous solution is 3:7.

[0077] The dispersion process is as follows:

[0078] Homogenize using an ultrafine homogenizer at 10,000 rpm for 2 minutes, then sonicate using a high-intensity ultrasonic processor in pulse mode at 525W pressure and amplitude for 2 minutes, with a 3-second working time and a 3-second interval during the pulse, to obtain an oil-in-water gel Pickering emulsion. Maintain the temperature at 80℃ during dispersion.

[0079] Comparative Example 1

[0080] A method for preparing an oil-in-water gel-pickering emulsion includes the following steps:

[0081] Step 1: Add beeswax to soybean oil and stir at 300 rpm and 80°C for 15 minutes to melt and evenly disperse the beeswax, thus obtaining the desired oil gel. The concentration of beeswax in the oil gel is 10.0% w / v.

[0082] Step 2: Add nanocellulose whiskers to the sodium alginate solution and mix thoroughly to obtain an aqueous solution. The concentration of NaCl in the aqueous solution is 60 mM, the concentration of sodium alginate is 0.2% w / v, and the concentration of nanocellulose whiskers is 0.5% w / v. Heat at 80℃ for 15 min.

[0083] Step 3: Thoroughly mix and disperse the oleogel from Step 1 with the aqueous solution from Step 2 to obtain the desired oil-in-water pickering emulsion (represented as CNW0 in the attached figure); the volume ratio of oleogel to aqueous solution is 3:7.

[0084] The dispersion process is as follows:

[0085] Homogenize using an ultrafine homogenizer at 10,000 rpm for 2 minutes, then sonicate using a high-intensity ultrasonic processor in pulse mode at 525W pressure and amplitude for 2 minutes, with a 3-second working time and a 3-second interval during the pulse, to obtain an oil-in-water gel Pickering emulsion. Maintain the temperature at 80℃ during dispersion.

[0086] Comparative Example 2

[0087] A method for preparing an oil-in-water gel-pickering emulsion includes the following steps:

[0088] Step 1: Add beeswax to soybean oil and stir at 300 rpm and 80°C for 15 minutes to melt and evenly disperse the beeswax, thus obtaining the desired oil gel. The concentration of beeswax in the oil gel is 10.0% w / v.

[0089] Step 2: Add nanocellulose whiskers to the sodium alginate solution and mix thoroughly to obtain an aqueous solution. The concentration of NaCl in the aqueous solution is 60 mM, the concentration of sodium alginate is 0.2% w / v, and the concentration of nanocellulose whiskers is 0.5% w / v. Heat at 80℃ for 15 min.

[0090] The preparation process of nanocellulose whiskers is as follows:

[0091] 100 mL of 5 mol / L hydrochloric acid and 100 mL of 20 mg / mL cellulose nanofibers were mixed and dispersed, and the mixture was heated in a constant-temperature shaking water bath at 100 °C and 100 rpm for 3 h to obtain modified cellulose nanofibers. After desulfurization, the mixture was first cooled, and then centrifuged and washed at 8000 rpm for 15 min. The supernatant was discarded to remove the hydrochloric acid, and centrifugation was repeated until the upper layer became turbid. The turbid suspension was poured into a dialysis bag with a molecular weight cutoff of 8000–14000 Da and dialyzed until the pH of the dialysate was neutral. The suspension in the dialysis bag was concentrated with polyethylene glycol 20000, and the concentrated sample suspension was collected and stored.

[0092] Step 3: Thoroughly mix and disperse the oleogel from Step 1 with the aqueous solution from Step 2 to obtain the desired oil-in-water pickering emulsion (represented as CNW3 in the attached figure); the volume ratio of oleogel to aqueous solution is 3:7.

[0093] The dispersion process is as follows:

[0094] Homogenize using an ultrafine homogenizer at 10,000 rpm for 2 minutes, then sonicate using a high-intensity ultrasonic processor in pulse mode at 525W pressure and amplitude for 2 minutes, with a 3-second working time and a 3-second interval during the pulse, to obtain an oil-in-water gel Pickering emulsion. Maintain the temperature at 80℃ during dispersion.

[0095] Comparative Example 3

[0096] A method for preparing an oil-in-water gel-pickering emulsion includes the following steps:

[0097] Step 1: Add beeswax to soybean oil and stir at 300 rpm and 80°C for 15 minutes to melt and evenly disperse the beeswax, thus obtaining the desired oil gel. The concentration of beeswax in the oil gel is 10.0% w / v.

[0098] Step 2: Add nanocellulose whiskers to the sodium alginate solution and mix thoroughly to obtain an aqueous solution. The concentration of NaCl in the aqueous solution is 60 mM, the concentration of sodium alginate is 0.2% w / v, and the concentration of nanocellulose whiskers is 0.5% w / v. Heat at 80℃ for 15 min.

[0099] The preparation process of nanocellulose whiskers is as follows:

[0100] 100 mL of 5 mol / L hydrochloric acid and 100 mL of 20 mg / mL cellulose nanofibers were mixed and dispersed, and the mixture was heated in a constant-temperature shaking water bath at 98 °C and 100 rpm for 6 h to obtain modified cellulose nanofibers. After desulfurization, the mixture was first cooled, and then centrifuged and washed at 8000 rpm for 15 min. The supernatant was discarded to remove the hydrochloric acid, and centrifugation was repeated until the upper layer became turbid. The turbid suspension was poured into a dialysis bag with a molecular weight cutoff of 8000–14000 Da and dialyzed until the pH of the dialysate was neutral. The suspension in the dialysis bag was concentrated with polyethylene glycol 20000, and the concentrated sample suspension was collected and stored.

[0101] Step 3: Thoroughly mix and disperse the oleogel from Step 1 with the aqueous solution from Step 2 to obtain the desired oil-in-water pickering emulsion (represented as CNW6 in the attached figure); the volume ratio of oleogel to aqueous solution is 3:7.

[0102] The dispersion process is as follows:

[0103] Homogenize using an ultrafine homogenizer at 10,000 rpm for 2 minutes, then sonicate using a high-intensity ultrasonic processor in pulse mode at 525W pressure and amplitude for 2 minutes, with a 3-second working time and a 3-second interval during the pulse, to obtain an oil-in-water gel Pickering emulsion. Maintain the temperature at 80℃ during dispersion.

[0104] Comparative Example 4

[0105] A method for preparing an oil-in-water gel-pickering emulsion includes the following steps:

[0106] Step 1: Add beeswax to soybean oil and stir at 300 rpm and 80°C for 15 minutes to melt and evenly disperse the beeswax, thus obtaining the desired oil gel. The concentration of beeswax in the oil gel is 10.0% w / v.

[0107] Step 2: Prepare the aqueous solution. The NaCl concentration in the aqueous solution is 60 mM, and the concentration of nanocellulose whiskers is 0.5% w / v. Heat at 80℃ for 15 min.

[0108] The preparation process of nanocellulose whiskers is as follows:

[0109] 100 mL of 5 mol / L hydrochloric acid and 100 mL of 20 mg / mL cellulose nanofibers were mixed and dispersed, and the mixture was heated in a constant-temperature shaking water bath at 99 °C and 100 rpm for 0.5 h to obtain modified cellulose nanofibers. After desulfurization, the mixture was first cooled, and then centrifuged and washed at 8000 rpm for 15 min. The supernatant was discarded to remove the hydrochloric acid, and centrifugation was repeated until the upper layer became turbid. The turbid suspension was poured into a dialysis bag with a molecular weight cutoff of 8000–14000 Da and dialyzed until the pH of the dialysate was neutral. The suspension in the dialysis bag was concentrated with polyethylene glycol 20000, and the concentrated sample suspension was collected and stored.

[0110] Step 3: Thoroughly mix and disperse the oleogel from Step 1 with the aqueous solution from Step 2 to obtain the desired oil-in-water pickering emulsion; the volume ratio of oleogel to aqueous solution is 3:7.

[0111] The dispersion process is as follows:

[0112] Homogenize using an ultrafine homogenizer at 10,000 rpm for 2 minutes, then sonicate using a high-intensity ultrasonic processor in pulse mode at 525W pressure and amplitude for 2 minutes, with a 3-second working time and a 3-second interval during the pulse, to obtain an oil-in-water gel Pickering emulsion. Maintain the temperature at 80℃ during dispersion.

[0113] Figure 1This diagram illustrates the density of sulfonic acid groups on the surface of the nanocellulose whiskers obtained in Examples 1-2 and Comparative Examples 1, 2, and 3 of this invention. As can be seen from the diagram, hydrochloric acid hydrolysis effectively cleaves sulfonic acid groups from the surface of the CNW. The sulfonic acid group densities of CNW were (0.28±0.01) mmol / g, (0.12±0.01) mmol / g, (0.08±0.00) mmol / g, and (0.08±0.01) mmol / g, respectively, when the hydrochloric acid hydrolysis time was 0.5, 1, 3, and 6 h. The sulfonic acid group density of CNW decreased significantly with increasing hydrochloric acid hydrolysis time, consistent with the decrease in the absolute value of the Zeta potential. When the hydrochloric acid hydrolysis time increased to 3 h, the CNW dispersion exhibited stratification, and the degree of stratification increased with further hydrolysis time. By changing the hydrochloric acid hydrolysis time, CNWs with different sulfonic acid group densities but similar fiber lengths were obtained.

[0114] Figure 2 These are schematic diagrams of the microstructure of the oil-in-water gel Pickering emulsions obtained in Examples 1-2 and Comparative Examples 1, 2, and 3 of the present invention. a) is a schematic diagram obtained using a laser confocal microscope, and b) is a schematic diagram of the emulsion particle size distribution. Figure 2 As shown in Figure a, the oleogel phase exists as a dispersed phase in the emulsion system, forming an oleogel pickering emulsion. CNW coats the surface of each spherical oleogel, successfully adsorbing at the oil-water interface to stabilize the emulsion. From... Figure 2 As shown in Figure b, the peak values ​​of the droplet size distribution of the emulsions obtained in Comparative Example 1 and Examples 1-4 are 3.7 μm, 4.4 μm, 4.7 μm, 5.2 μm, and 5.1 μm, respectively. With the decrease in the density of sulfonic acid groups on the CNW surface, the peak value of the emulsion droplet size distribution increases and the distribution range shifts to the right. This indicates that the droplet size of the emulsion increases with the increase of hydrochloric acid hydrolysis time. With the decrease in the density of sulfonic acid groups on the CNW surface, the electrostatic repulsion between particles weakens, making the particles more prone to aggregation and leading to an increase in the emulsion droplet size.

[0115] Figure 3 The diagrams above show the stability test results of the oil-in-water gel Pickering emulsions obtained in Examples 1-2 and Comparative Examples 1, 2, and 3 of this invention. a) shows the macroscopic morphology during storage; b) shows the CI test results during storage; c) shows an optical microscope image during storage; and d) shows the statistical results of the average particle size during storage. Figure 3 As can be seen from Figure a, on day 0, a uniform milky white emulsion could be prepared using CNWs with different densities of sulfonic acid groups. Water precipitation was observed in the emulsion on both day 7 and day 20. This is due to phase separation caused by gravity. Under the same storage period, as the density of sulfonic acid groups in the CNW decreased, the volume of water precipitated from the emulsion first decreased significantly and then increased significantly. From... Figure 3As shown in Figure b, during the 20-day storage period, after 20 days, as the density of CNW sulfonic acid groups decreased, the CI of the emulsion stabilized at (41.7±2.1)%, (35.1±0.7)%, (40.0±2.1)%, (44.3±2.8)%, and (43.9±0.6)%, respectively. With the decrease in the density of CNW sulfonic acid groups, the CI first decreased significantly and then increased significantly. Both excessively high and low CNW sulfonic acid group densities are detrimental to the storage stability of the oil-in-water gel Pickering emulsion. The sulfonic acid group density obtained by the CNW sulfonic acid group preparation method selected in this invention meets the requirements. By observing the changes in CI, two stages of emulsion stabilization can be observed as the density of CNW sulfonic acid groups decreases. In the first stage, the decrease in sulfonic acid group density weakens the electrostatic repulsion between CNWs, making CNWs more prone to aggregation. When the CNWs covering the surface of the emulsion droplets are in an appropriate aggregation state, a relatively stable emulsion can be obtained. At the same time, the electrostatic repulsion of the emulsion is sufficient to overcome van der Waals attraction and prevent oil droplet aggregation, thus improving the stability of the emulsion. In the second stage, due to the decrease in sulfonic acid group density, the electrostatic repulsion between CNWs continues to decrease, and the repulsive interaction between droplets is no longer stronger than the attractive interaction, leading to flocculation of emulsion droplets and a decrease in emulsion stability.

[0116] from Figure 3 As shown in Figure c, the droplet size of the emulsion increases significantly with decreasing CNW sulfonic acid group density. After 7 days of storage, the degree of droplet flocculation increases. After 20 days of storage, the degree of droplet flocculation continues to increase. For the same storage time, decreasing CNW sulfonic acid group density leads to increased droplet flocculation. This is because decreasing CNW sulfonic acid group density reduces the electrostatic repulsion between droplets, resulting in increased droplet flocculation. Figure 3 In the figure, 'd' represents the statistical results of droplet size. During storage, the average droplet size of emulsions prepared with CNWs of different sulfonic acid group densities did not change significantly. This is because electrostatic repulsion exists between the droplets, preventing droplet aggregation. Furthermore, oleogels are semi-solid; even if emulsion droplets flocculate, they do not merge into larger droplets but remain adhered together at their original size, resulting in no significant change in the average droplet size during storage.

[0117] In Examples 1, 3, 4 and Comparative Examples 1-4, curcumin was added simultaneously in step 1 of the preparation process. The concentration of curcumin in the oleogel solution was 1.0% (w / v). The mixture was stirred for 1 hour in a water bath at 60°C using a magnetic stirrer and sonicated for 30 minutes to ensure that as much curcumin as possible was dissolved.

[0118] Figure 4The diagram shows the stability test results of the oil-in-water gel Pickering emulsions obtained in Examples 1, 3, and 4 and Comparative Example 4 of this invention. a) shows the macroscopic morphology during storage; b) shows the CI test results during storage; c) shows an optical microscope image during storage; and d) shows the statistical results of the average particle size during storage. Figure 4 As shown in Figure a, a uniform milky-white emulsion could be prepared at different sodium alginate concentrations on day 0. Water precipitation was observed in the emulsion on both day 7 and day 20. This is due to phase separation caused by gravity. Under the same storage period, the volume of water precipitated from the emulsion decreased significantly with increasing sodium alginate concentration. Figure 3 As shown in Figure b, when the sodium alginate concentrations were 0%, 0.2%, 0.5%, and 1.0%, the CI of the emulsion stabilized at (44.5±2.5)%, (41.7±2.1)%, (35.6±2.5)%, and (15.7±2.0)%, respectively, after 20 days of storage at 25℃. The significant decrease in CI indicates that increasing the sodium alginate concentration is beneficial for improving the storage stability of the emulsion. The addition of sodium alginate creates a stronger network structure in the continuous phase of the emulsion, and the increased concentration of sodium alginate also increases the viscosity of the continuous phase. This reduces the flowability of the dispersed phase, prevents droplet flocculation and aggregation, and improves the stability of the emulsion. Figure 3 As shown in Figure c, the droplet size increases significantly with increasing sodium alginate concentration. Emulsions with sodium alginate concentrations of 0% and 0.2% showed flocculation after 7 days of storage. Emulsions prepared with sodium alginate concentrations of 0.5% and 1.0% showed no significant change in droplet state after 20 days of storage. Figure 4 As shown in Figure d, with the sodium alginate concentration increasing from 0% to 1.0%, the average droplet size of the Pickering emulsion increased from (4.3±0.2) μm to (9.2±0.1) μm. There was no significant difference in the average droplet size of the emulsions prepared at different sodium alginate concentrations during storage. The relatively stable average droplet size during storage is due to the electrostatic repulsion between droplets, preventing droplet aggregation. As the oleogel is semi-solid, even if the emulsion droplets flocculate, they do not merge into larger droplets but remain adhered together at their original size. Furthermore, the increased sodium alginate concentration increases the viscosity of the continuous phase, preventing flocculation and aggregation of emulsion droplets during storage. The emulsion stability significantly improves with increasing sodium alginate concentration. The emulsion with a sodium alginate concentration of 1.0% exhibits excellent storage stability.

[0119] Figure 5 This is a comparison of the encapsulation of curcumin in the oil-in-water gel Pickering emulsions obtained in Example 4 and Comparative Example 4 of the present invention. a represents the encapsulation rate of curcumin, and b represents the retention rate during storage. Figure 5As shown in Figure a, the encapsulation efficiencies of curcumin prepared from emulsions with sodium alginate concentrations of 0% and 1.0% were (80.9±0.7)% and (86.3±3.7)%, respectively, indicating a significant increase in the curcumin encapsulation efficiency. The encapsulation efficiency of curcumin significantly improved with the addition of sodium alginate. Figure 5 As shown in Figure b, during the 20-day storage period, the retention rate of curcumin in the emulsions prepared under conditions of 0% and 1.0% sodium alginate concentrations significantly decreased with prolonged storage time. After 20 days of storage, the retention rate of the emulsion with 0% sodium alginate concentration was (89.5±0.7)%, while the retention rate of the emulsion with 1.0% sodium alginate concentration was (92.8±0.9)%. Compared with the emulsion with 0% sodium alginate concentration, the emulsion with 1.0% sodium alginate concentration showed a significantly higher retention rate of curcumin and significantly improved chemical stability. This is because the addition of sodium alginate resulted in the presence of more large-diameter droplets in the emulsion. The presence of these large droplets reduced the contact area between oxygen and curcumin within the oil droplets, thus slowing down the oxidative degradation of curcumin.

[0120] The oil-in-water gel Pickering emulsion obtained in this invention exhibits a high encapsulation efficiency for oil- and poorly water-soluble nutrients. Curcumin can be uniformly dispersed and immobilized within the three-dimensional network structure of the oil gel. The highly stable emulsion system can prevent curcumin from being destroyed during gastric digestion, thereby improving its bioavailability.

[0121] Figure 6 The figure represents the release rate of curcumin during gastrointestinal digestion after encapsulation of curcumin in the oil-in-water gel Pickering emulsion obtained in Example 4 and Comparative Example 4 of this invention. From... Figure 6As can be seen, the release of curcumin in the gastrointestinal tract gradually increases with increasing digestion time. The emulsion containing 0% sodium alginate encapsulating curcumin released (41.5±2.0)% of the curcumin after 2 hours of digestion in the stomach, while the emulsion prepared with 1.0% sodium alginate showed a significantly lower curcumin release rate of only (11.9±0.3)%. This result indicates that the emulsion prepared with 1.0% sodium alginate can effectively protect curcumin in the gastric environment and deliver it to the next stage. The emulsion prepared with 0% sodium alginate releases the vast majority of curcumin in the stomach, resulting in a cumulative curcumin release of only (30.9±1.0)% after 2 hours of intestinal digestion. In the first 30 minutes after digestion in the intestine, an emulsion with a sodium alginate concentration of 1.0% showed a rapid release of (46.3±4.4)% of curcumin. After 2 hours of intestinal digestion, the cumulative release of curcumin during this stage was (62.3±1.0)%. The release rate of curcumin during intestinal digestion significantly increased with the addition of sodium alginate. This is because the emulsion droplet interface membrane prepared at a sodium alginate concentration of 0% is relatively fragile. Under the acidic conditions of the stomach, a relatively large portion of the emulsion droplet interface membrane is destroyed after complete gastric digestion, resulting in the release of a large amount of curcumin during the gastric stage. Consequently, only a small portion of curcumin can be effectively encapsulated and delivered to the intestinal stage for further release. In contrast, the emulsion droplet interface membrane prepared at a sodium alginate concentration of 1.0% is more stable, effectively protecting curcumin during gastric digestion and ensuring its delivery to the intestine for release. In the first 30 minutes of simulated intestinal digestion, lipase rapidly reacts with lipids in the smaller droplets of the emulsion, simultaneously disrupting most of the emulsion droplet interface membranes and releasing a large amount of curcumin. Subsequently, the gel network structure of the oleogel slows down the reaction between lipase and lipids, causing the later release rate of curcumin to plateau. The method used in this invention to simulate the gastrointestinal environment is a prior art method, and the methods for testing and calculating the release rate also employ existing techniques.

[0122] Figure 7 This refers to the bioavailability of curcumin encapsulated in the oil-in-water gel Pickering emulsion obtained in Example 4 and Comparative Example 4 of this invention. Figure 7The results show that the bioavailability of curcumin in the 0% sodium alginate emulsion was (38.6±2.1)%, while that in the 1.0% sodium alginate emulsion was (45.6±0.3)%, indicating a significant increase in bioavailability. Digestible substances such as fatty acids, monoacylglycerols, and bile salts can integrate into mixed micelles, thereby promoting the solubility of curcumin. The 0% sodium alginate emulsion releases a large amount of curcumin in the stomach, leading to curcumin loss; only a small portion of curcumin can be effectively encapsulated and delivered to the intestinal tract for digestion and absorption. In contrast, the 1.0% sodium alginate emulsion can encapsulate and deliver the vast majority of curcumin to the intestine before releasing it. Therefore, the bioavailability of curcumin in the 1.0% sodium alginate emulsion is significantly higher than that in the 0% sodium alginate emulsion.

[0123] The oil-in-water gel pickering emulsion of this invention contains sodium alginate. The droplet size of the emulsion increased from (4.3±0.2) μm to (9.2±0.1) μm, with no significant change in droplet size during storage. The concentration of soluble solids (CI) decreased from (44.5±2.5)% to (15.7±2.0)%. The increased sodium alginate concentration is beneficial for improving the stability of the emulsion. Adding sodium alginate can improve the encapsulation capacity of curcumin in the emulsion and also helps improve the stability of curcumin during storage. Adding 1.0% sodium alginate increased the encapsulation rate of curcumin in the oil-in-water gel pickering emulsion by 5.4% and the retention rate after 20 days of storage at 25°C by 3.3%. The increased sodium alginate concentration is beneficial for improving the protective ability of the oil-in-water gel pickering emulsion for curcumin during in vitro digestion, enabling more effective delivery of curcumin to the intestine for digestion and absorption. Curcumin release was significantly reduced in the stomach and significantly increased in the intestines, resulting in a 7.0% improvement in bioavailability. The addition of hydrochloric acid-treated CNW to the oil-in-water gel Pickering emulsion further enhanced its stability.

Claims

1. A method for preparing an oil-in-water gel-Pickering emulsion, characterized in that, Includes the following steps: Step 1: Disperse the liquid oil and beeswax to obtain an oil gel; Step 2: Add nanocellulose whiskers to sodium alginate solution and mix thoroughly to obtain an aqueous solution; wherein the mass ratio of sodium alginate to nanocellulose whiskers is 2-10:5; the nanocellulose whiskers are modified nanocellulose whiskers after desulfurization treatment with hydrochloric acid; The preparation method of modified nanocellulose whiskers is as follows: Hydrochloric acid and nanocellulose whiskers were mixed and heated with shaking at 98–100 °C and 100 rpm for 0.5–1 h to obtain modified nanocellulose whiskers; wherein the mass ratio of hydrochloric acid to nanocellulose was 9:

10. Step 3: Thoroughly mix and disperse the oleogel from Step 1 with the aqueous solution from Step 2 to obtain the desired oil-in-water gel Pickering emulsion.

2. The method for preparing an oil-in-water gel-Pickering emulsion according to claim 1, characterized in that, After the hydrochloric acid and nanocellulose whiskers have reacted, the modified nanocellulose whiskers can be obtained by cooling, centrifugation, washing, and dialysis. The centrifugation speed is 8000 rpm and the centrifugation time is 15 min.

3. The method for preparing an oil-in-water gel-Pickering emulsion according to claim 1, characterized in that, The oleogel preparation process in step 1 is as follows: Add beeswax to soybean oil at a concentration of 10.0% w / v; stir at 300 rpm and 80 ℃ for 15 min to obtain the desired oleogel.

4. The method for preparing an oil-in-water gel-Pickering emulsion according to claim 1, characterized in that, In step 2, the aqueous solution is heated at 80 °C for 15 min.

5. The method for preparing an oil-in-water gel-Pickering emulsion according to claim 1, characterized in that, The mixing and dispersion process in step 3 is as follows: First, homogenize for 2 minutes at an emulsifier speed of 10,000 rpm; Then, pulse ultrasound was performed at 525 W for 2 min. During the ultrasound process, work for 3 seconds, pause for 3 seconds, and repeat the ultrasound cycle.

6. The method for preparing an oil-in-water gel-Pickering emulsion according to claim 1, characterized in that, The aqueous solution in step 2 also contains NaCl, with a NaCl concentration of 60 mM.

7. The water-in-oil gel-based Pickering emulsion obtained by any of the preparation methods described in claims 1 to 6.

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