Stabilizer for Pickering emulsion and application thereof

Abstract

The invention provides a stabilizer for Pickering emulsion and application of the stabilizer, and relates to the technical field of Pickering emulsion preparation. The stabilizing agent for the Pickering emulsion is obtained by compounding 6 '-O-caffeoyl arbutin and cellulose nanocrystals. In specific application, the 6'-O-caffeoyl arbutin and the cellulose nanocrystals are prepared into a water phase, and then the water phase is mixed with an oil phase to prepare the Pickering emulsion. According to the preparation method, the defects in the prior art are overcome, the stability of the Pickering emulsion is effectively improved, meanwhile, the oxidation resistance effect of the Pickering emulsion is further enhanced, and the application value of the Pickering emulsion is improved.

Description

Technical Field

[0001] This invention relates to the field of Pickering emulsion preparation technology, and more specifically to a stabilizer for Pickering emulsions and its application. Background Technology

[0002] With the growing demand for green and sustainable materials in the cosmetics, food, and drug delivery systems industries, Pickering emulsions based on natural polymers and nanoparticles have gradually become a research hotspot. Pickering emulsions are emulsions stabilized by solid particles as emulsifiers, and compared with traditional emulsions using surfactants, they have better thermodynamic stability, lower toxicity, and superior performance in multiphase systems.

[0003] The stability of Pickering emulsions stems from the irreversible adsorption of solid particles, which form a dense film at the oil-water interface, effectively preventing droplet aggregation and co-growth. Compared to traditional surfactant emulsions, Pickering emulsions exhibit superior physicochemical stability, particularly under heat treatment and pH variations. Due to this enhanced stability, Pickering emulsions have wide applications in cosmetics, food, and pharmaceuticals. Especially in active molecule delivery and food packaging, Pickering emulsions act as carriers to stabilize the release of bioactive substances, increasing their bioavailability and shelf life.

[0004] To improve the stability of Pickering emulsions, stabilizers are typically added. However, most existing stabilizers are micron or nano-sized solid particles. These particles stabilize the emulsion by forming a physical barrier at the oil-water interface, preventing droplet aggregation. However, these stabilizers have limited applications in current fields. Furthermore, the antioxidant effect of the Pickering emulsion itself is a key research focus at this stage. Therefore, enhancing the antioxidant effect of Pickering emulsions while improving their stability is the main research direction at present. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a stabilizer for Pickering emulsions and its application, which effectively improves the stability of Pickering emulsions and further enhances their antioxidant effects, thereby increasing the application value of Pickering emulsions.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A stabilizer for Pickering emulsions, said stabilizer comprising the following components in parts by weight: 6'- O- coffee aryl arbutin (CA) 5-20 parts, cellulose nanocrystals (CNCs) 30-50 parts.

[0007] The application of the stabilizer for Pickering emulsion in the preparation of Pickering emulsion, the application is to prepare the stabilizer into an aqueous phase and then mix with an oil phase to prepare the Pickering emulsion.

[0008] Preferably, the method of preparing the stabilizer into an aqueous phase comprises the following steps: S1-1, cellulose nanocrystals are added to deionized water to prepare a cellulose nanocrystal suspension by using an ultrasonic cell disruptor; S1-2, 6'-O-β-D-glucopyranosyl-3, 4, 5-trihydroxybenzyl-β-D-glucopyranoside is added to the cellulose nanocrystal suspension; O - coffee aryl arbutin, stirring at a speed of 7000-10000 r / min for 1-3 min, and then ultrasonic treatment, to prepare a CA / CNCs composite water suspension as the aqueous phase.

[0009] Preferably, the ultrasonic treatment in step S1-2 is 200W for 3min.

[0010] Preferably, the mass concentration of 6'-O-β-D-glucopyranosyl-3, 4, 5-trihydroxybenzyl-β-D-glucopyranoside in the aqueous phase is 0.05%-0.2%, and the mass concentration of cellulose nanocrystals is 0.3%-0.5%. O

[0011] Preferably, the specific method of preparing the stabilizer into an aqueous phase and then mixing with an oil phase to prepare the Pickering emulsion comprises the following steps: S2-1, the aqueous phase and the oil phase are mixed and then pre-emulsified by stirring to obtain a pre-emulsion for standby; S2-2, the pre-emulsion is treated by ultrasonic under ice water bath conditions to obtain the Pickering emulsion.

[0012] Preferably, the volume ratio of the aqueous phase to the oil phase in step S2-1 is 3-5:1.

[0013] Preferably, the pre-emulsification by stirring in step S2-1 is stirring at a speed of 1000-1400 r / min for 1-3 min.

[0014] Preferably, the ultrasonic treatment in step S2-2 is at a power of 200-300W for 3-8min.

[0015] The present application provides a stabilizer for Pickering emulsion and its application, which has the following advantages compared with the prior art: The present application uses 6'-O-β-D-glucopyranosyl-3, 4, 5-trihydroxybenzyl-β-D-glucopyranoside as the stabilizer for Pickering emulsion. O ​The coffee acyl arbutin and cellulose nanocrystal complex can significantly improve the static storage stability of the prepared O / W Pickering emulsion and improve the dynamic mechanical stability of the Pickering emulsion, further improve the antioxidant effect of the Pickering emulsion, so that the Pickering emulsion has important application potential in the fields such as functional cosmetics, health food and drug delivery system which have strict requirements on stability and oxidation protection. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 FIG. 1 is a schematic diagram of CA suspensions with different CA mass concentrations in Example 1 of the present application, wherein the CA mass concentrations in the CA suspensions from left to right are 0 wt.%, 0.025 wt.%, 0.05 wt.%, 0.1 wt.%, 0.2 wt.%; Figure 2 FIG. 3 is a schematic diagram of the zeta potential of the CA suspensions with different CA mass concentrations in the example of the present application; Figure 3 FIG. 4 is a schematic diagram of the zeta potential of the CA / CNCs suspensions with different CA mass concentrations in Example 1 of the present application; Figure 4 FIG. 5 is a schematic diagram of CNCs suspensions and CA / CNCs suspensions with different CNCs mass concentrations in Example 1 of the present application, wherein the CNCs mass concentrations in the CNCs suspensions and CA / CNCs suspensions from left to right are 0 wt.%, 0.05 wt.%, 0.1 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.%, 0.5 wt.%; Figure 5 FIG. 6 is a schematic diagram of the zeta potential of the CNCs suspensions with different CNCs mass concentrations in Example 1 of the present application; Figure 6 FIG. 7 is a schematic diagram of the zeta potential of the CA / CNCs suspensions with different CNCs mass concentrations in Example 1 of the present application; Figure 7 FIG. 8 is a schematic diagram of the delamination of the Pickering emulsion prepared with the aqueous phase with different CNCs mass concentrations in Example 2 of the present application after storage for 7 days, wherein the CNCs mass concentrations from left to right are 0 wt.%, 0.05 wt.%, 0.1 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.%, 0.5 wt.%; Figure 8 FIG. 9 is a schematic diagram of the emulsification rate, PDI and zeta potential of the Pickering emulsion prepared with the aqueous phase with different CNCs mass concentrations in Example 2 of the present application after storage for 7 days; Figure 9 Schematic diagram of Pickering emulsion prepared by different water phases in Example 2 of the present application, from left to right, the water phases are deionized water, CA suspension, CNCs suspension and CA / CNCs suspension; Figure 10 Schematic diagram of droplet diameter of Pickering emulsion prepared by different water phases in Example 2 of the present application; Figure 11 Schematic diagram of morphological changes of Pickering emulsion prepared by different water phases in Example 2 of the present application (optical microscope 400 times image), wherein a is blank group, b is CA group, c is CNCs group, d is CA / CNCs group; Figure 12 Schematic diagram of spatial structure of Pickering emulsion prepared by different water phases in Example 2 of the present application; wherein a is blank group, b is CA group, c is CNCs group, d is CA / CNCs group; Figure 13 Schematic diagram of staining results of Pickering emulsion prepared by different water phases in Example 2 of the present application (laser scanning confocal microscope 630 times magnification image); wherein a is blank group, b is CA group, c is CNCs group, d is CA / CNCs group; Figure 14 TIP measurement image of Pickering emulsion after storage for 7 days in Example 3 of the present application, wherein a is blank group, b is CA group, c is CNCs group, d is CA / CNCs group; Figure 15 Schematic diagram of viscosity change of emulsion prepared by different water phases in Example 4 of the present application under different shear stress; Figure 16 Storage modulus and loss modulus of emulsion prepared by different water phases in Example 4 of the present application; Figure 17 Schematic diagram of DPPH· scavenging capacity of each group of emulsion in Example 5 of the present application; Figure 18 Schematic diagram of ABTS + scavenging capacity of each group of emulsion in Example 5 of the present application; Figure 19 Schematic diagram of change of curcumin encapsulation rate in Pickering emulsion under different light conditions in Example 6 of the present application; Figure 20 Schematic diagram of change of particle size, PDI and zeta potential of Pickering emulsion under different temperature conditions in Example 6 of the present application; Figure 21This is a schematic diagram showing the changes in particle size, PDI, and zeta potential of Pickering emulsion under different pH conditions in Example 6 of the present invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] The specific preparation method of cellulose nanocrystals used in the following examples is as follows: First, lignin and hemicellulose in wood were removed using microwave-assisted eutectic solvent (DES) in conjunction with hydrogen peroxide (H2O2) to prepare cellulose. A choline chloride / lactic acid (ChCl / LA) DES system was prepared at a molar ratio of 1:2. Wood flour was mixed with DES at a solid-liquid ratio of 1:20 (g / mL), and the mixture was stirred at 200 W microwave power and 130℃ for 30 min. After the reaction, the mixture was filtered, and the filter cake was washed with deionized water until neutral. After preliminary decolorization with anhydrous ethanol, it was further treated with 30% H2O2 at 75℃ until white, washed with deionized water until neutral, and then freeze-dried under vacuum to constant weight to obtain wood cellulose with lignin and hemicellulose removed. Then, the wood cellulose was mixed with deionized water at a mass concentration of 0.2 wt.% to prepare a suspension. This suspension was ultrasonically treated at a frequency of 20 kHz and an output power of 1200 W for 30 min to obtain a CNCs suspension. Finally, the CNCs were obtained by filtration to remove water, washing the filter cake, and freeze-drying. Example 1:

[0019] 1. Preparation of CA / CNCs aqueous suspension: (1) CNCs were added to deionized water and then an aqueous suspension of CNCs was prepared using an ultrasonic cell disruptor (450 W, 30 min). (2) Add CA to the CNCs aqueous suspension, first stir at 8000 r / min for 1 min, then use 200 W ultrasonic treatment for 3 min to prepare CA / CNCs aqueous suspension; 2. Following the preparation method described above, CNCs with a constant mass concentration (0.2 wt.%) were prepared, 6'- O - CA / CNCs suspension with caffeoyl arbutin concentrations of 0 wt.%, 0.025 wt.%, 0.05 wt.%, 0.1 wt.%, and 0.2 wt.%; Additionally, 6'-O - Caffeoyl arbutin was directly added into deionized water, stirred at 8000 r / min for 1 min, and then treated with ultrasonic at 200 W for 3 min to prepare CA suspensions with CA mass concentrations of 0 wt.%, 0.025 wt.%, 0.05 wt.%, 0.1 wt.% and 0.2 wt.%.

[0020] 3. Morphology and stability of CA suspensions and CA / CNCs suspensions with different CA mass concentrations were detected: (1) The morphologies of CA suspensions and CA / CNCs suspensions with different CA mass concentrations are shown in FIG. 2 (and from left to right, the CA mass concentrations are 0 wt.%, 0.025 wt.%, 0.05 wt.%, 0.1 wt.% and 0.2 wt.%); Figure 1 For CA suspensions: no obvious flocculation phenomenon was observed, and because CA is slightly soluble in water, a suspension was formed when the CA mass concentration reached 0.1 wt.%; For CA / CNCs suspensions: as CA increased from 0 wt.% to 0.05 wt.%, the transparency of the CA / CNCs suspension improved significantly, because hydrogen bonds were formed between the water-soluble CA and the CNCs network, causing the uniformly dispersed nanoparticles to partially aggregate.

[0021] Comparing the CA suspensions and CA / CNCs suspensions in the upper and lower figures, the suspensions with CA mass concentrations of 0.1 wt.% and 0.2 wt.% showed a more transparent milky white state and were more uniform overall, indicating that the CA insoluble suspension particles could also form hydrogen bonds with the CNCs network, improving the dispersibility of the suspension.

[0022] (2) Zeta potentials of CA suspensions and CA / CNCs suspensions with different CA mass concentrations: Zeta potential, as a core electrochemical parameter of colloidal system stability, directly represents the electrostatic repulsion potential between dispersed particles. The smaller the molecules or dispersed particles, the higher the absolute value of zeta potential, which can effectively inhibit Ostwald ripening and heterogeneous aggregation. Conversely, the lower the absolute value of zeta potential, the greater the tendency of coagulation or clumping, leading to irreversible flocculation of the dispersed phase. When the absolute value of zeta potential exceeds 30 mV, the emulsion shows high stability.

[0023] The specific zeta potential detection results are shown in FIG. 3 and FIG. 4: Figure 2 Figure 3 In CA suspensions ( Figure 2 ​​​The stability of CA suspension increases with increasing CA concentration, and the zeta potential of the suspension tends to stabilize when the CA concentration reaches 0.1 wt.%. In CA / CNCs suspension ( Figure 3 In a 0.2 wt.% CNCs suspension, appropriately increasing CA (0-0.1 wt.%) can improve the stability of the suspension. However, when CA reaches 0.2 wt.%, the stability of the suspension decreases.

[0024] 4. Following the preparation method in step 1 above, prepare CA / CNCs suspensions with constant CA mass concentration (0.1 wt.%) and different CNCs mass concentrations (CNCs mass concentrations of 0 wt.%, 0.05 wt.%, 0.1 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.%, and 0.5 wt.%). In addition, CNCs of different masses were added to deionized water, and CNCs suspensions of different mass concentrations were prepared by ultrasonic cell disruptor (450 W, 30 min) (CNCs mass concentrations were 0 wt.%, 0.05 wt.%, 0.1 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.%, 0.5 wt.%). 5. Detect the morphology and stability of CNCs suspensions and CA / CNCs suspensions with different CNCs mass concentrations: (1) The morphology of CNCs suspensions with different CNCs mass concentrations and CA / CNCs suspensions are as follows: Figure 4 As shown (and the mass concentrations of CNCs from left to right are 0 wt.%, 0.05 wt.%, 0.1 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.%, and 0.5 wt.%). Figure 4 When the mass concentration of CNCs is 0.05 wt.% or 0.1 wt.%, the CNCs suspension exhibits slight flocculation and stratification. However, with the addition of CA, the stratification of the CA / CNCs suspension is significantly improved, and the overall suspension becomes more uniform.

[0025] (2) Zeta potential of CNCs suspensions with different CNCs mass concentrations and CA / CNCs suspensions: Specific results are as follows Figure 5 and Figure 6 As shown, Figure 5 The stability of the CNCs suspension gradually increased with the increase of CNCs mass concentration, and the zeta potential trend tended to stabilize after CNCs reached 0.3 wt.%. Figure 6The stability of the CA / CNCs suspension with a fixed mass concentration of CA (0.1 wt.%) is improved compared with the CNCs suspension corresponding to the mass concentration of the CNCs in the CA / CNCs suspension.

[0026] It can be known from the above detection that the CA / CNCs suspension is most stable when the mass concentration of CA is 0.1 wt.% and the mass concentration of CNCs is 0.3 wt.%. Example 2:

[0027] Referring to the above example 1, the CA / CNCs suspension is prepared as an aqueous phase for standby; 0.025 g of curcumin is uniformly mixed with 50 g of olive oil, and the mixture is subjected to constant temperature magnetic stirring at 60°C for 3 h until the curcumin is dissolved, serving as an oil phase; The aqueous phase and the oil phase are mixed at a volume ratio of 4:1, pre-emulsified under stirring at 12000 rpm for 1 min, and then subjected to ultrasonic treatment at 250W for 5 min to obtain a Pickering emulsion.

[0028] 1. The ratio of CA to CNCs in the above aqueous phase is limited to 1:3, and the aqueous phase with CNCs mass concentrations of 0 wt.%, 0.05 wt.%, 0.1 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.% and 0.5 wt.% is prepared respectively to prepare different Pickering emulsions; The emulsion performance and emulsified phase volume fraction of the Pickering emulsion with different CNCs mass concentrations in the aqueous phase after storage for 7 days are detected, and the specific results are shown in Figure 7 and Figure 8 Figure 7 From left to right, the layered conditions of the Pickering emulsion prepared with the aqueous phase with CNCs mass concentrations of 0 wt.%, 0.05 wt.%, 0.1 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.% and 0.5 wt.% after storage for 7 d are shown, and with the increase of the CNCs mass concentration in the aqueous phase, the emulsification rate of the emulsion gradually increases, and the emulsification layer tends to be stable when the CNCs mass concentration is 0.3 wt.% (CA 0.1 wt.%).

[0029] Figure 8 With the increase of the CA / CNCs mass concentration, the absolute value of zeta potential increases, and PDI decreases, indicating that the emulsion is more stable, and the droplet size is more uniform, and uniformity is the key to ensure the consistency of the quality and performance of the Pickering emulsion.

[0030] ​2. Using 0.3 wt.% CNCs suspension, 0.1 wt.% CA suspension, and CA / CNCs suspension with CA concentration of 0.1 wt.% and CNCs concentration of 0.3 wt.% as the aqueous phase, Pickering emulsions with different aqueous phases were prepared according to the preparation method described above. (1) Observe the volume fraction of the emulsion phase in each group of Pickering emulsions, specifically as follows: Figure 9 As shown in the figure, the aqueous phases of the Pickering emulsion from left to right are deionized water (NC), CA suspension, CNCs suspension, and CA / CNCs suspension, respectively. As can be seen from the figure, CNCs can be absorbed at the oil-water interface without the introduction of CA. Due to the charge repulsion between CNCs, their hydrogen bond network is unstable, resulting in relatively poor emulsion stability. After adding CA to CNCs, CNCs flocculate, the particle size increases, more connections are formed at the oil-water interface, the shell is more compact, and the stability of the Pickering emulsion is further improved. CA is not suitable as a dispersant alone for preparing Pickering emulsions. (2) Based on this, a nanoparticle size potentiometer was used to detect the droplet diameter of each group of Pickering emulsions. The specific results are shown in [the table below]. Figure 10 The diameter of the emulsion droplets decreased with the addition of CA, and the same trend was observed when CA was added to CNCs. This is because hydrogen bonds were formed between CA and CNCs, causing CA to adsorb onto the surface of CNCs, which weakened the electrostatic repulsion between CNCs and improved the stability of the emulsion.

[0031] (3) Observe the morphological changes of Pickering emulsions prepared with different aqueous phases using an optical microscope, specifically as follows: Figure 11 As shown, Figure 11 Figure a shows that when deionized water is in the aqueous phase (blank group), the emulsion droplets are small in size but exhibit significant heterogeneity in distribution; Figure 11 Figure b shows that when CA suspension is used as the aqueous phase (CA group), the droplet size is reduced and the dispersion uniformity is improved; Figure 11 The data in the middle section shows that when the CNCs suspension is in aqueous phase (CNCs group), the average droplet diameter increases, but it exhibits better monodispersity and dense packing characteristics. Figure 11 The data in the middle section shows that when the CA / CNCs suspension is used as the aqueous phase (CA / CNCs group), the droplet diameter is smaller and the uniformity of distribution is further improved. At this time, the average droplet diameter is 3.26 μm, the emulsion stability is the best, and the emulsification rate is the highest.

[0032] (4) Microscopic analysis of each group of Pickering emulsions was performed using cryo-scanning electron microscopy and laser confocal scanning microscopy: After the prepared sample was left to stand for one week and shaken, the spatial structure of the emulsion was observed under a cryo-scanning electron microscope. Figure 12 As shown; among which CA group ( Figure 12 (b) The emulsion, after one week of storage, compared to the control group ( Figure 12 The emulsion in group a) did not have a large area of ​​dispersed oil layer, indicating that CA has a certain emulsifying effect; the CNCs group ( Figure 12 In emulsion c), most droplets are entangled together to form a network structure through connection and dispersion. This is because the charge repulsion between CNCs causes them to disperse into the aqueous phase. CNCs tend to be discretely distributed in the aqueous system, resulting in a significant reduction in their interfacial coverage at the oil-water interface; CA / CNCs group ( Figure 12 Cryo-scanning electron microscopy characterization of the emulsion (d) revealed a high-density monodisperse droplet arrangement. Compared to the CA and CNCs groups, the three-dimensional network structure formed by CNCs dissociated in this composite system, with residual fiber bundles observed only in local droplet gaps. The droplet size uniformity within the system was significantly improved, and the CA / CNCs composite formed heterogeneous adsorption domains at the interface, thereby endowing the emulsion with excellent long-term stability.

[0033] The microstructure and distribution characteristics of Pickering emulsions were further characterized using CLSM; Nile red (488 / 539) and Nile blue (365 / 435) were used to stain the aqueous and oil phases of stable emulsions from different aqueous groups (blank group, CA group, CNCs group, and CA / CNCs group), respectively. The results are as follows: Figure 13 As shown: In the blank group ( Figure 13 The droplets in group a) exhibited trailing flow dynamics, showing extreme instability; the CNCs group ( Figure 13 (c) and CA / CNCs group ( Figure 13 The emulsion in group d) exhibits a larger droplet size, mainly due to the presence of CNCs, but it also has good interfacial coverage and stability, forming a robust and uniquely shaped structure with a tightly ordered interfacial structure; the CA group ( Figure 13 Although the droplet size of the emulsion in group b) was smaller than that in the CNCs group and the CA / CNCs group, the distribution was relatively dispersed, and no obvious blue interface ring was observed. In particular, a clear blue interface ring was observed in the CA / CNCs group by CLSM. Figure 13D). The blue interfacial ring can prove the particle adsorption and the formation of the interfacial film at the interface, and the blue ring of the CA / CNCs group becomes more obvious and completely covers the oil droplets, indicating that the adsorption of CA and CNCs can promote the formation of a dense structure, which helps to form a strong physical barrier to prevent droplet coalescence. The hydrogen bond interaction between CA and CNCs is the reason for the induced stronger interfacial film. In addition, the formation of the hydrogen bond network of the continuous phase ensures the high stability of the emulsion, and the particles are simultaneously anchored and adsorbed between two or more oil droplets, forming an emulsification network structure. Example 3:

[0034] Interfacial tension identification of each group of emulsions: The interfacial tension IFT between the water phase (deionized water, CA suspension, CNCs suspension and CA / CNCs suspension) and the oil phase (olive oil) was measured by a surface tension meter (SZ-CAMC32). Figure 14 Among them, the mass concentration of CNCs is fixed at 0.3 wt.%, the mass concentration of CA is 0.1 wt.%, and the influence of the way of changing the water phase composition on the interfacial tension is explored. The experimental results are shown in Table 1. When the CA suspension is used as the water phase to stabilize the emulsion, the interfacial tension (122.43 mN / m) is much larger than that of the blank group (5.65 mN / m) and the CNCs suspension system (12.15 mN / m). Compared with the CNCs system without adding CA, the oil-water interfacial tension of the CA / CNCs system with CA added also increases (29.19 mN / m), but it is much lower than the interfacial tension value of the water phase and the oil phase composed of the CA suspension. This shows that CA and CNCs are effectively combined. Theoretical derivation considers that the increase of oil-water interfacial tension will weaken the stability of the emulsion, but this study finds that the CA modified CNCs system presents an abnormal synergistic phenomenon. This contradictory phenomenon is due to the regulatory advantage of the hydrogen bond network between CA and CNCs on the interfacial adsorption kinetics, which dominates the effect significantly beyond the influence of the change of the interfacial tension on the stability.

[0035] The specific results are as follows in Table 1: Table 1 Example 4:

[0036] Rheological test: The Pickering emulsion prepared by different water phases was detected. All the emulsions showed shear thinning phenomenon under stable shear stress, The specific results are as follows in Table 1: Figure 15 ​: The emulsion viscosity of CA group, CNCs group and CA / CNCs group were all higher than that of blank group, and the emulsion viscosity of CA / CNCs group was lower than that of CA group and CNCs group, which reflected the interaction between CA and CNCs; In addition, considering that the emulsification rate of blank group and CA group was far less than that of CNCs group and CA / CNCs group, with the increase of shear viscosity, the emulsification rate was significantly improved. The viscosity of CNCs group and CA / CNCs group changed more linearly with the shear rate. Overall, the addition of CNCs significantly improved the emulsification rate, while the hydrogen bond interaction between CA and CNCs weakened the hydrogen bond network between CNCs, resulting in a decrease in the shear viscosity of the emulsion and better flowability.

[0037] Rheological characterization data as shown in Figure 16 : revealed the viscoelastic response law of Pickering emulsion: the storage modulus (G') was continuously higher than the loss modulus (G") in the full frequency domain, which confirmed that the system had a solid-like viscoelastic response characteristic. In the CA group, the values of G' and G" were close, indicating that the system was in a dynamic balance state between elastic recovery and viscous dissipation during deformation, resulting in relatively weak structure stability. In the CNCs group and CA / CNCs group, the viscoelastic modulus of the emulsion increased, and the increase in G' was significantly higher than that in G", which confirmed that CNCs could effectively strengthen the structure stability of the emulsion. Example 5:

[0038] Verification of the influence of CA / CNCs suspension as water phase on the antioxidant effect of Pickering emulsion: 0.3 wt.% CNCs suspension, 0.1 wt.% CA suspension and CA / CNCs suspension with CA mass concentration of 0.1 wt.% and CNCs mass concentration of 0.3 wt.% were prepared as water phase according to the above example; Olive oil with or without the addition of curcumin was used as oil phase to prepare different Pickering emulsions (the specific preparation method and parameters refer to Example 2); Evaluation of DPPH· and ABTS + · of Pickering emulsion prepared with different water phase (with / without curcumin); Specific results as shown in Figure 17DPPH· scavenging capacity of each group of emulsions, showing that the DPPH· scavenging capacity of the emulsion is related to the addition of curcumin, CA and CNCs, wherein the Pickering emulsion encapsulating curcumin shows better DPPH· scavenging rate than the emulsion without encapsulating curcumin. In addition, CNCs do not show obvious DPPH· scavenging capacity, but the addition of CNCs can improve the DPPH· scavenging capacity of the Pickering emulsion encapsulating curcumin. The Pickering emulsion stabilized by CA alone as a stabilizer does not well encapsulate curcumin in terms of DPPH· scavenging rate, however, the DPPH· scavenging capacity of the CA suspension as the water phase is not high as a whole, because CA will quickly degrade and lose antioxidant activity when stored in the natural environment without any protection mechanism. Whether or not curcumin is encapsulated, the DPPH· scavenging capacity of the Pickering emulsion stabilized by CA / CNCs is the best in the same group, which shows that the CA / CNCs system can effectively protect CA and enable it to exert corresponding antioxidant activity.

[0039] Figure 18 ABTS· scavenging capacity of each group of emulsions, wherein the Pickering emulsion prepared by the CA / CNCs suspension as the water phase shows better ABTS· scavenging rate and curcumin encapsulation rate. Among them, compared with curcumin, CA has a higher proportion of ABTS· scavenging capacity in the antioxidant activity of the emulsion. In addition, CNCs do not show obvious ABTS· scavenging capacity, but the scavenging rate is higher than that of the blank control group, because the ultrasonic treatment of the sample can enhance its antioxidant capacity, due to the cavitation effect and the turbulence caused by physical shearing, thereby causing changes in the conformation of the emulsion. + + + + Example 6:

[0040] Verification of the stability influence of the Pickering emulsion with the CA / CNCs suspension as the water phase: Prepare the CA / CNCs suspension as the water phase (the mass concentration of CNCs is 0.3 wt.%, and the mass concentration of CA is 0.1 wt.%); mix 0.025 g of curcumin with 50 g of olive oil, and magnetically stir at 60°C for 3 h until the curcumin is dissolved, as the oil phase; Mix the water phase and the oil phase according to a volume ratio of 4:1, stir at 12000 rpm for 1 min for pre-emulsification, and then ultrasonically treat at 250W for 5 min to obtain the Pickering emulsion.

[0041] ​​​​1. Time-dependent variation of curcumin encapsulation efficiency in Pickering emulsion under different light conditions. The specific results are shown in FIG. 2: Figure 19 During the 30-day observation period, the curcumin encapsulation efficiency of the emulsion stored in the dark remained stable at above 85% with minimal fluctuation. This stability highlights the positive role of the dark environment in maintaining the structural integrity and curcumin loading capacity of the emulsion. In contrast, the emulsion exposed to natural light showed a gradual decrease in curcumin encapsulation efficiency after 3 days, dropping to 71.35% by the 15th day, and then stabilizing. This decrease is attributed to the poor light stability of CA. Although the CNCs network initially mitigated the oxidation of CA at the oil-water interface, prolonged exposure to natural light caused the degradation of CA. The oxidized CA weakened the intermolecular interactions with CNCs, reducing the emulsion's ability to retain curcumin, and thus decreasing the encapsulation efficiency. These findings clearly demonstrate that light can disrupt the interfacial interactions between CA and CNCs, which are crucial for retaining curcumin. Therefore, storage in the dark is essential for maintaining high encapsulation efficiency and long-term stability of the emulsion, which preserves the molecular synergy between CA and CNCs and ensures the performance stability of the curcumin-loaded emulsion, which is of critical importance for optimizing the shelf life and functional efficacy in antioxidant delivery applications.

[0042] 2. Variation of particle size, PDI, and zeta potential of Pickering emulsion at different temperatures. The specific results are shown in FIG. 3: Figure 19 Within the temperature range of 30-80°C, the average droplet diameter of the Pickering emulsion remained stable at about 3.5 μm, and the zeta potential also remained stable at about -36 mV. Only the PDI showed a slight upward trend, rising from about 0.22 at 30°C to about 0.32 at 80°C, indicating that temperature mainly affects the uniformity of droplet size distribution. High temperatures weaken the hydrogen bonding between CA, CNCs, and within the CNCs network, while enhancing hydrophobic interactions, leading to slight aggregation of droplets and broadening of the particle size distribution. At 90°C, the static stability of the emulsion was destroyed, with the average droplet diameter increasing to about 4 μm and the zeta potential decreasing to about -31 mV. The CA-CNCs network at the oil-water interface lost its spatial confinement ability on the droplets, triggering massive aggregation and partial droplet rupture. Therefore, the temperature range of 30-80°C better maintains the structural integrity of the emulsion, indicating its good thermal stability.

[0043] 3. Variation of particle size, PDI, and zeta potential of Pickering emulsion at different pH values. The specific results are shown in FIG. 4: Figure 20 ​​​When the pH value was increased from 3.0 to 7.0, the droplet size increased and the stability decreased. Homogenization after the pH value was adjusted from 7.0 to 11.0 could reduce the droplet size, but could not improve the stability. In acidic conditions, part of the water-soluble CA was protonated, which enhanced the hydrogen bonding between the CA and the hydroxyl groups on the CNCs surface. Transition from acidic conditions to neutral conditions induced the creaming of the emulsion, because the CNCs detached from the interface, leading to the coarsening of the oil droplets and the destabilization of the system. At pH 11.0, the phenolic compounds might react with the biopolymers in the suspension, and the plant polyphenols were prone to oxidation and oligomerization in the presence of dissolved oxygen, forming high-molecular-weight products with low solubility. The solubility of CA, which was inherently poor, was further reduced. The affinity between CA and CNCs through hydrogen bonding promoted the deposition of CNCs on the surface, inducing the crosslinking of the nanofibrils and the construction of a continuous network around the oil droplets, thus stabilizing the discrete oil droplets. Therefore, acidic conditions (pH 3.0→7.0) induced the coarsening of the oil droplets and the weakening of the interfacial film, while alkaline conditions (pH 11.0) allowed the partial restructuring of the droplets. Despite the pH responsiveness, the Pickering emulsion was better maintained in acidic conditions, which provided support for the optimization of specific application scenarios and storage conditions.

[0044] In summary, the CA / CNCs suspension was most stable for the Pickering emulsion in water at light-protected, 30-80℃, and acidic conditions.

[0045] The above examples are only used to illustrate the technical solutions of the present application, but not limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacements for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A stabilizer for a Pickering emulsion, characterized by: The stabilizer consists of the following parts by mass: 6' O - caffeoyl arbutin 5-20 parts, cellulose nanocrystal 30-50 parts.

2. Use of a stabilizer for Pickering emulsions as claimed in claim 1 for the preparation of Pickering emulsions, characterized in that: The application is prepared by mixing the stabilizer prepared in the water phase with the oil phase.

3. Use according to claim 2, characterized in that, The method for preparing the stabilizer in the water phase comprises the following steps: S1-1, adding cellulose nanocrystals into deionized water to prepare a cellulose nanocrystal suspension by using an ultrasonic cell disruptor; S1-2, adding 6'-caffeoyl arbutin in the cellulose nanocrystal suspension O -caffeoyl arbutin, stirring at a speed of 7000-10000 r / min for 1-3 min, and then ultrasonic treatment, to obtain 6'-caffeoyl arbutin / cellulose nanocrystal composite aqueous suspension O -caffeoyl arbutin, stirring at a speed of 7000-10000 r / min for 1-3 min, and then ultrasonic treatment, to obtain 6'-caffeoyl arbutin / cellulose nanocrystal composite aqueous suspension 4. Use according to claim 3, characterized in that: The ultrasonic treatment in the step S1-2 is performed at 200 W for 3 min.

5. Use according to claim 3, characterized in that: The aqueous phase 6'- O - The mass concentration of caffeoyl arbutin is 0.05%-0.2%, and the mass concentration of cellulose nanocrystals is 0.3%-0.5%.

6. Use according to claim 3, characterized in that, The specific method for preparing the Pickering emulsion by mixing the stabilizer prepared in the water phase with the oil phase comprises the following steps: S2-1, mixing the water phase and the oil phase and then stirring to pre-emulsify, to obtain a pre-emulsion for standby; S2-2, ultrasonic treatment of the pre-emulsion under the condition of ice water bath to obtain a Pickering emulsion.

7. Use according to claim 6, characterized in that: The volume ratio of the water phase to the oil phase in the step S2-1 is 3-5:

1.

8. Use according to claim 6, characterized in that: The stirring in the step S2-1 is performed at a rotating speed of 1000-1400 r / min for 1-3 min.

9. Use according to claim 6, characterized in that: The ultrasonic treatment in the step S2-2 is performed at a power of 200-300 W for 3-8 min.

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