Nanoscale Pickering emulsion based on tea soup nanoparticles and its preparation method and application

Abstract

The present invention relates to the field of nanotechnology, and in particular to a nanoscale Pickering emulsion based on tea soup nanoparticles, and a preparation method and application thereof. The nanoscale Pickering emulsion comprises an oil phase and an aqueous phase; the aqueous phase contains tea soup nanoparticles; the tea soup nanoparticles are composed of nano-biomacromolecule-polyphenol composite particles and a dielectric layer wrapped on the surface of the nano-biomacromolecule-polyphenol composite particles and having the same charge; and the average size of the Pickering emulsion is less than 300 nm. The present application adopts tea soup as a raw material, avoids the introduction of external factors such as metal ions, and improves food safety from the source. At the same time, by optimizing the process, polyphenol nanoparticles with a nanometer size of less than 20 nm are efficiently separated from the tea soup, which reduces the complexity of process parameter control while realizing the preparation of nanoscale Pickering emulsion and improving the stability and antioxidant properties of the emulsion.

Description

Technical Field

[0001] The present invention relates to the field of nanotechnology, and in particular to a nano-scale Pickering emulsion based on tea soup nanoparticles, and a preparation method and application thereof. Background Art

[0002] As an important food processing carrier, emulsions are widely used in many fields such as food, cosmetics, and medicine. They have significant functions in emulsification, preservation, and anti-oxidation. However, the oxidation of oil components in emulsions is a major challenge in their application. Oil oxidation not only causes off-flavors and loss of nutrients in food, but also generates a series of lipid oxidation products. These products may pose potential safety risks to human health, such as causing gastrointestinal discomfort and accelerating aging. Therefore, how to effectively prevent oil oxidation and improve the stability of emulsions is a key technical problem that needs to be solved in the field of food processing.

[0003] Among the numerous antioxidants, natural polyphenols have become an ideal choice for inhibiting lipid oxidation due to their excellent antioxidant capacity and good food safety. These natural polyphenols are widely derived from plants such as tea, grapes, and blueberries. Their unique phenolic hydroxyl structure can effectively scavenge free radicals and inhibit lipid oxidation reactions, making them of great application value. In recent years, nanoparticles containing polyphenols have been gradually used as antioxidants to stabilize Pickering emulsion systems. As a highly efficient emulsification technology, Pickering emulsions enhance the stability of the oil-water interface through nanoparticles, demonstrating unique advantages in emulsion systems.

[0004] Existing technologies have achieved, to a certain extent, the stabilization of Pickering emulsion systems through polyphenol nanoparticles, but they still face many challenges in practical applications. First, polyphenols themselves have high chemical activity and instability, and the preparation process of their nanoparticles often requires the introduction of external factors such as metal ions to improve stability. However, the introduction of these metal ions may bring potential food safety hazards. In addition, during the preparation of Pickering emulsions, the particle size and distribution of nanoparticles have a significant impact on the stability, antioxidant effect and sensory quality of the emulsion. Particles with larger particle sizes are prone to cause emulsion stratification and instability, while particles with smaller particle sizes and uniform distribution can significantly improve the physical stability and antioxidant properties of the emulsion. However, there is currently a lack of a simple method that can simultaneously prepare nanoparticles with small particle size, uniform distribution and rich in natural polyphenols. Summary of the Invention

[0005] The present invention aims to overcome the defects of Pickering emulsion in the prior art, such as unstable chemical properties and large emulsion particle size, and provides a nano-scale Pickering emulsion based on tea soup nanoparticles and its preparation method and application to overcome the above-mentioned shortcomings.

[0006] To achieve the above-mentioned purpose, the present invention is implemented through the following technical solutions:

[0007] In a first aspect, the present invention first provides a nanoscale Pickering emulsion based on tea soup nanoparticles.

[0008] It includes an oil phase and a water phase;

[0009] The aqueous phase contains tea soup nanoparticles;

[0010] The tea soup nanoparticles are composed of nano biomacromolecule-polyphenol composite particles and a dielectric layer wrapped on the surface of the nano biomacromolecule-polyphenol composite particles and having the same charge; and

[0011] The average size of the nanoscale Pickering emulsion is less than 300 nm.

[0012] The nanoscale Pickering emulsion described in this application first utilizes the interaction between food macromolecules (such as proteins or polysaccharides) and polyphenols to construct nanoscale biomacromolecule-polyphenol composite particles. The nanoscale biomacromolecule-polyphenol composite particles then serve as an emulsifier, thereby achieving mixing of the oil phase and the aqueous phase, ultimately forming the Pickering emulsion. This approach effectively prevents metal ion contamination of polyphenol nanoparticles, compared to prior art nanoparticle emulsifiers primarily composed of polyphenols and metal ions.

[0013] However, the present applicants have discovered in experiments that the surfaces of biomacromolecule-polyphenol composite particles are generally rich in hydrogen bond donor groups and hydrogen bond acceptor groups that can be used to form hydrogen bonds. Therefore, adjacent particles are also subject to certain hydrogen bonding interactions, resulting in a certain degree of agglomeration. At the same time, due to certain electrostatic interactions between adjacent biomacromolecule-polyphenol composite particles, the agglomeration between the biomacromolecule-polyphenol composite particles is exacerbated, resulting in the prepared biomacromolecule-polyphenol composite particles having an excessively large particle size. Particles with larger particle sizes are prone to stratification and instability in Pickering emulsions.

[0014] Therefore, in response to the above-mentioned problems, the present application also wraps a dielectric layer with the same charge on the outside of the biomacromolecule-polyphenol composite particles. Since the newly added dielectric layer carries the same charge, an interfacial repulsion effect will occur between the biomacromolecule-polyphenol composite particles. At the same time, due to the introduction of the dielectric layer, the affinity between the biomacromolecule-polyphenol composite particles and water is improved, and the water solubility of some biomacromolecules is enhanced, causing the particles to undergo "salt dissolution phenomenon", thereby effectively alleviating the aggregation of particles through the above two methods, so that the obtained tea soup nanoparticles have a smaller particle size, and then after it is applied as an emulsifier to the Pickering emulsion, the particle size of the obtained emulsion can be greatly reduced (the average size can reach less than 300 nm), ultimately improving its own physical and chemical stability.

[0015] Preferably, the size of the tea soup nanoparticles is less than 20 nm.

[0016] When tea nanoparticles are smaller than 20 nm, they adsorb more effectively at the oil-water interface in a Pickering emulsion. Because the particles are smaller, there are more of them per unit volume, forming a denser adsorption layer at the interface. This denser adsorption layer acts like a stronger "wall," better preventing the coalescence of oil droplets.

[0017] At the same time, the repulsive force generated by the charge carried by smaller particles can work over a shorter distance. Since the particles in the emulsion are relatively close together, this charge repulsion is more effective in preventing particle aggregation, thereby further improving the stability of the emulsion and allowing it to maintain a well-dispersed state even during long-term storage and complex environmental conditions (such as temperature fluctuations and mechanical vibration).

[0018] Preferably, the polyphenol content in the biomacromolecule-polyphenol composite particles exceeds 10%; and

[0019] Biomacromolecules include proteins and / or polysaccharides.

[0020] Polyphenols are a class of compounds with multiple phenolic hydroxyl groups that can scavenge free radicals by donating hydrogen atoms. In emulsion systems, high levels of polyphenols can effectively prevent oxidation of the oil phase and other components within the emulsion. Therefore, when the polyphenol content exceeds 10%, the antioxidant properties are significantly enhanced. In food emulsions, if the oil phase contains unsaturated fatty acids, polyphenols can react with free radicals, preventing the oxidative rancidity of fatty acids and extending the shelf life of the food. In cosmetic emulsions, high levels of polyphenols can protect the skin from damage by free radicals in the environment and reduce the skin cell damage caused by free radicals, thereby reducing the appearance of wrinkles and improving skin elasticity.

[0021] Furthermore, proteins and polysaccharides possess excellent spatial structures and intermolecular interactions. For example, proteins can interact with polyphenols through hydrogen bonds and van der Waals forces, forming stable composite structures that achieve functions such as emulsification and moisturizing. Polysaccharides provide steric hindrance and a certain degree of viscosity, preventing aggregation of composite particles. Therefore, when proteins and / or polysaccharides are complexed with polyphenols, they can achieve synergistic and comprehensive functions beyond their antioxidant properties. Furthermore, proteins and polysaccharides are common components in living organisms and exhibit excellent biocompatibility. When these composite particles are used in emulsions (such as in the biopharmaceutical or food industries), this biocompatibility can reduce potential toxicity and irritation to the human body.

[0022] In a second aspect, the present invention further provides a method for preparing the nanoscale Pickering emulsion based on tea nanoparticles as described above, which comprises the following steps:

[0023] (S.1) Adding tea leaves to water, boiling, filtering, and intercepting to obtain intercepted tea soup;

[0024] (S.2) treating the retained tea soup by ultracentrifugation to remove large particles in the retained tea soup and obtain a supernatant containing nano-biomacromolecule-polyphenol composite particles;

[0025] (S.3) adding a monovalent metal salt to the supernatant to form a dielectric layer on the surface of the biomacromolecule-polyphenol composite particles, thereby obtaining an aqueous phase containing tea nanoparticles;

[0026] (S.4) Homogenizing the oil phase and the water phase to obtain the nanoscale Pickering emulsion based on tea soup nanoparticles.

[0027] The present application has found that after tea leaves are boiled, the proteins, polysaccharides and polyphenols present in the tea leaves will spontaneously self-assemble to form nano biomacromolecule-polyphenol composite particles of varying sizes. When the tea leaves are intercepted and treated, the large-sized particles present in the tea leaves can be removed, while the biomacromolecule-polyphenol composite particles with nanometer size are retained. In order to prevent the nano-sized biomacromolecule-polyphenol composite particles from aggregating with each other, the present application adds a monovalent metal salt to the supernatant. After adding the monovalent metal salt, the dielectric constant of the solution can be effectively improved. At the same time, part of the monovalent metal salt can adhere to the surface of the biomacromolecule-polyphenol composite particles, thereby forming a thicker dielectric layer, which enhances the interfacial repulsion between the particles and causes a "salt dissolution phenomenon", effectively alleviating the aggregation between the particles.

[0028] Preferably, the tea leaves in step (S.1) are fermented tea leaves.

[0029] The present application found that fermented tea has a higher content of Maillard reaction products than unfermented tea, which makes it have a higher emulsification effect.

[0030] More preferably, the tea leaves in step (S.1) are any one of black tea, green tea, oolong tea and Pu'er tea.

[0031] Preferably, the boiled tea soup in step (S.1) is first filtered through gauze to remove most of the tea leaves, then a 0.45 μm filter membrane is used to remove small-sized tea leaves and solid impurities, and then the tea soup is ultrafiltered through a hollow cellulose membrane ultrafiltration system (100 kDa) to finally obtain retained tea soup.

[0032] Preferably, the retained tea soup is processed by a two-step ultracentrifugation method in the step (S.2), firstly removing large particles therein by low speed centrifugation, and then processing by high speed centrifugation, so that the nano-biomacromolecule-polyphenol composite particles enter the supernatant.

[0033] Preferably, the monovalent metal salt in step (S.3) is a sodium salt or a potassium salt.

[0034] Sodium salt or potassium salt can effectively shield the aggregation force between nanoparticles, reduce aggregates, and obtain nanoparticle components with smaller particle size.

[0035] Preferably, the concentration of the monovalent metal salt in step (S.3) is 0.3%-1.0%.

[0036] Preferably, in the step (S.4), the volume ratio of the oil phase to the water phase is (5-30): (70-95).

[0037] In a third aspect, the present invention also provides applications of the nanoscale Pickering emulsion based on tea soup nanoparticles in the fields of food, cosmetics and medicine.

[0038] Therefore, compared with the traditional method, the present invention has the following technical advantages:

[0039] (1) Green source and safety: Using tea soup as raw material avoids the introduction of external factors such as metal ions, thus improving food safety from the source;

[0040] (2) Simple and efficient preparation: By optimizing the process, polyphenol nanoparticles with a size less than 20 nm and rich in polyphenols are efficiently separated from tea soup, reducing the complexity of process parameter control;

[0041] (3) Performance optimization and stability improvement: Different from conventional micron-scale Pickering emulsions, this strategy enables the preparation of nanoscale Pickering emulsions, which improves the stability of the emulsion while enhancing the antioxidant properties of lipids. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is an electron microscope image of the tea soup nanoparticles prepared in Example 1.

[0043] Figure 2 This is an electron microscope image of the nanoscale Pickering emulsion stabilized by tea soup nanoparticles in Example 2.

[0044] Figure 3 This is an electron microscope image of the nanoscale Pickering emulsion stabilized by tea soup nanoparticles in Example 3.

[0045] Figure 4 This is an electron microscope image of the nanoscale Pickering emulsion stabilized by tea soup nanoparticles in Example 4.

[0046] Figure 5 This is an electron microscope image of the nanoscale Pickering emulsion stabilized by tea soup nanoparticles in Example 5. DETAILED DESCRIPTION

[0047] The present invention will be further described below with reference to specific embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below generally represent only a portion of the present invention, rather than all of the embodiments. Therefore, all other embodiments derived by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0048] Example 1: Preparation of tea nanoparticles

[0049] (1) Weigh 10 g of black tea leaves, with a tea-to-water ratio of 1:30, and heat in an induction cooker water bath to maintain boiling for 10 min. Then, use a 200-mesh gauze to coarsely filter to remove most of the tea leaves. The filtrate is then filtered through a 0.45 μm filter membrane. The resulting filtrate is fixed to a 150 mL volumetric flask. Finally, the tea soup is ultrafiltered using a hollow cellulose membrane ultrafiltration system (100 kDa) to retain the retained tea soup. This step revealed that there is more than one type of nano-biomacromolecule-polyphenol composite particles in the tea soup, and there are nano-biomacromolecule-polyphenol composite particles in the range of 10-1000 nm.

[0050] (2) The ultrafiltered tea soup was further processed by ultracentrifugation. The first step was centrifugation at 10,000 g for 15 to 30 min to remove large particles. The tea soup was then centrifuged at 36,000 g for 60 to 120 min to obtain a supernatant containing nano-biomacromolecule-polyphenol composite particles. 0.3 to 3.0% sodium chloride was further added to the supernatant to shield the aggregation force between the nanoparticles and break up the aggregates to obtain a sol containing tea soup nanoparticle components with smaller particle sizes.

[0051] The characterization results are shown in Figure 1 Electron microscopy revealed that the resulting tea nanoparticles were less than 20 nm in size, with an average particle size of approximately 15.8 nm. They were spherical and had an absolute surface charge of less than 10 mV. Analysis of the plant's active ingredients revealed a polyphenol content exceeding 10% within the nanoparticles, along with proteins, polysaccharides, and other components. This suggests that the tea nanoparticles are composed of a combination of biomacromolecules and polyphenols, are naturally derived, and are stable in food systems. The presence of these components further enhances the subsequent emulsification and emulsion stability.

[0052] Example 2: Preparation of Nanoscale Pickering Emulsion Stabilized by Tea Nanoparticles

[0053] A corresponding volume of rapeseed oil was added according to the oil-water volume ratio, i.e., rapeseed oil: tea soup nanoparticle sol = 5:95 (the tea soup nanoparticle sol is the sol obtained in step (2) of Example 1, with a concentration of about 1%). A high-speed shearing machine T18DS25 was used to homogenize at 10,000-15,000 rpm for 3 minutes to prepare a crude emulsion. The crude emulsion was then further homogenized by a microfluidizer with a set pressure of 1,000 bar and 3 homogenization times to obtain a Pickering emulsion stabilized by tea soup ultra-small nanoparticles. The obtained emulsion was characterized by dynamic light scattering, and the results are as follows: Figure 2 The results showed that the average size of the obtained emulsion was less than 300 nm, which was a nanoscale Pickering emulsion.

[0054] Example 3: Preparation of Nanoscale Pickering Emulsion Stabilized by Tea Nanoparticles

[0055] A corresponding volume of rapeseed oil was added according to the oil-water volume ratio, i.e., rapeseed oil: tea soup nanoparticle sol = 10:90 (the tea soup nanoparticle sol is the sol obtained in step (2) of Example 1, with a concentration of about 1%). A high-speed shearing machine T18DS25 was used to homogenize at 10,000-15,000 rpm for 3 minutes to prepare a crude emulsion. The crude emulsion was then further homogenized by a microfluidizer with a set pressure of 1,000 bar and 3 homogenization times to obtain a Pickering emulsion stabilized by tea soup ultra-small nanoparticles. The obtained emulsion was characterized by dynamic light scattering, and the results are as follows: Figure 3 The results showed that the average size of the obtained emulsion was less than 250 nm, which was a nanoscale Pickering emulsion.

[0056] Example 4: Preparation of Nanoscale Pickering Emulsion Stabilized by Tea Nanoparticles

[0057] A corresponding volume of rapeseed oil was added according to the oil-water volume ratio, i.e., rapeseed oil: tea soup nanoparticle sol = 20:80 (the tea soup nanoparticle sol is the sol obtained in step (2) of Example 1, with a concentration of about 1%). A high-speed shearing machine T18DS25 was used to homogenize at 10,000-15,000 rpm for 3 minutes to prepare a crude emulsion. The crude emulsion was then further homogenized by a microfluidizer with a set pressure of 1,000 bar and 3 homogenization times to obtain a Pickering emulsion stabilized by tea soup ultra-small nanoparticles. The obtained emulsion was characterized by dynamic light scattering, and the results are as follows: Figure 4 The results showed that the average size of the obtained emulsion was less than 350 nm, which was a nanoscale Pickering emulsion.

[0058] Example 5: Preparation of Nanoscale Pickering Emulsion Stabilized by Tea Nanoparticles

[0059] A corresponding volume of rapeseed oil was added according to the oil-water volume ratio, i.e., rapeseed oil: tea soup nanoparticle sol = 30:70 (the tea soup nanoparticle sol is the sol obtained in step (2) of Example 1, with a concentration of about 1%). A high-speed shearing machine T18DS25 was used to homogenize at 10,000-15,000 rpm for 3 minutes to prepare a crude emulsion. The crude emulsion was then further homogenized by a microfluidizer with a set pressure of 1,000 bar and 3 homogenization times to obtain a Pickering emulsion stabilized by tea soup ultra-small nanoparticles. The obtained emulsion was characterized by dynamic light scattering, and the results are as follows: Figure 5 The results showed that the average size of the obtained emulsion was less than 500 nm, which was a nanoscale Pickering emulsion.

[0060] Example 6: Comparison of physical stability of tea soup nano-Pickering emulsion, tea soup Pickering emulsion, and conventional emulsion

[0061] Preparation of tea soup Pickering emulsion: rapeseed oil was added according to the oil-water volume ratio, i.e., rapeseed oil: retained tea soup = 5:95 (retained tea soup is the retained tea soup obtained in step (1) of Example 1), and a crude emulsion was prepared by homogenization at 10,000-15,000 rpm for 3 min using a high-speed shearing machine T18DS25. The crude emulsion was then further homogenized using a microfluidizer with a set pressure of 1,000 bar and 3 homogenization times to obtain a tea soup Pickering emulsion with a droplet size of approximately 13 μm. Nanoparticles of varying sizes (with a particle size range of 150-1,000 nm) are present in the tea soup, so the emulsion prepared based on it is also a Pickering emulsion.

[0062] Preparation of a conventional emulsion: The corresponding volume of rapeseed oil was added according to the oil-to-water volume ratio, i.e., rapeseed oil: whey protein aqueous solution = 5:95 (the final concentration of the whey protein aqueous solution was 1%), where the final protein concentration was 1%. A coarse emulsion was prepared by homogenization at 10,000-15,000 rpm for 3 min using a high-speed shearing machine T18DS25. The coarse emulsion was then further homogenized using a microfluidizer with a set pressure of 1,000 bar and three homogenization cycles to obtain a conventional emulsion stabilized with whey protein isolate as an emulsifier. The particle size of the emulsion droplets was 8 μm.

[0063] Test Method

[0064] The emulsion stability was evaluated by centrifugation, and the results are shown in Table 1. A certain amount of emulsion was placed in a centrifuge tube and centrifuged at high speed (8000 r / min, 15 min). The total mass of oil and water separated from the emulsion after centrifugation was measured, and the centrifugal stability was calculated using the formula: Centrifugal stability = (W1-W2) / W1*100%

[0065] Wherein, W1 represents the total weight (g) of the emulsion before centrifugation; W2 represents the total weight (g) of the non-emulsified layer after centrifugation.

[0066] The obtained emulsion was subjected to centrifugal stability test, and the results are shown in Table 1.

[0067] Table 1 Physical stability of tea soup nano-Pickering emulsion, tea soup Pickering emulsion, and conventional emulsion

[0068] sample Centrifugal stability (%) Tea Infusion Nano Pickering Lotion 80.0±3.1 Tea Pickering Lotion 56.7±5.8 Regular lotion 64.1±4.3

[0069] The tea-infusion nano-Pickering emulsion exhibited excellent physical stability, with a centrifugal retention rate of 80.0 ± 3.1%. This is because a large number of tea-infusion nanoparticles with a size below 20 nm covered the emulsion interface, forming a dense coating. This high particle coverage prevented droplet coalescence. Furthermore, the nano-sized droplets reduced the effect of creaming under gravity. However, micron-sized tea-infusion Pickering emulsions exhibited significant stratification upon standing, and their physical stability was even less satisfactory. This is because the number of tea-infusion nanoparticles with a size greater than 150 nm in an equal volume of tea-infusion was high, resulting in a high concentration of large micro- and nano-sized aggregates. Consequently, the resulting tea-infusion Pickering emulsion had a low particle coverage rate, and droplets tended to coalesce to form larger droplets upon centrifugation. Emulsions prepared using this emulsion were more prone to creaming than nano-sized emulsions and exhibited significantly lower physical stability. Conventional emulsions prepared using whey protein isolate exhibited a centrifugal retention rate of approximately 64.1 ± 4.3%, exhibiting lower physical stability than the tea-infusion nano-Pickering emulsion.

[0070] Example 7 Comparison of Oxidation Performance of Tea Soup Nano-Pickering Emulsion, Tea Soup Pickering Emulsion, and Conventional Emulsion

[0071] The tea soup nano-Pickering emulsion, tea soup Pickering emulsion and conventional emulsion were placed in a 50°C oven to accelerate their lipid oxidation reactions. The hydroperoxide value (POV) of the oil in the emulsion was determined by the currently valid GB 5009.227-2023, and the malondialdehyde (MDA) production of the oil in the emulsion was determined by the currently valid GB 5009.181-2016 at 1, 5 and 10 days. The results are shown in Tables 2 and 3.

[0072] Table 2 POV values ​​of tea soup nano-Pickering emulsion, tea soup Pickering emulsion, and conventional emulsion under oxidation induction

[0073] Time (days) Tea Soup Nano Pickering Emulsion POV (meq / oil kg) Tea Soup Pickering Emulsion POV (meq / oil kg) Whey protein isolate emulsion POV (meq / oil kg) 1 0.25±0.025 0.33±0.018 0.67±0.067 5 0.69±0.13 0.92±0.14 1.23±0.038 10 1.03±0.17 2.0±0.11 2.70±0.19

[0074] Table 3 MDA values ​​of tea soup nano-Pickering emulsion, tea soup Pickering emulsion, and conventional emulsion under oxidation induction

[0075] Time (days) Tea Soup Nano Pickering Emulsion MDA (mM) Tea Decoction Pickering Emulsion MDA (mM) Whey protein isolate emulsion MDA (mM) 1 0.12±0.0086 0.15±0.0018 0.18±0.016 5 0.33±0.019 0.412±0.014 0.55±0.028 10 0.57±0.051 0.87±0.041 1.37±0.034

[0076] All three emulsions exhibited significant lipid oxidation with prolonged storage. Comparison of the oxidation products, hydroperoxide (POV) and malondialdehyde (MDA), generated in the three emulsions revealed that the tea-based nano-Pickering emulsion exhibited the best oxidative stability. This is because a large number of tea-based nanoparticles coated the droplet surface, forming a physical barrier that prevented oxygen and other pro-oxidants from contacting the oil. Furthermore, tea-based nanoparticles are bio-based materials loaded with antioxidants, and the polyphenols on their surface preferentially react with oxygen, effectively slowing the oil oxidation process. The tea-based nano-Pickering emulsion exhibited significantly better lipid oxidation resistance than the micron-sized tea-based Pickering emulsion. This is because the larger surface area of ​​tea-based nanoparticles less than 20 nm allows for greater antioxidant activity. In comparison, the conventional emulsion using whey protein isolate as an emulsifier exhibited the worst oxidative stability, experiencing the highest degree of oil oxidation at the same storage time.

[0077] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Persons skilled in the art may make various modifications, additions, or substitutions to the described specific embodiments without departing from the spirit of the present invention or exceeding the scope of the appended claims.

Claims

1. A method for preparing a nanoscale Pickering emulsion based on tea nanoparticles, characterized in that: The following steps are involved: (S.1) boiling tea leaves with water and filtering to obtain retained tea soup, wherein the filtration comprises gauze filtration, membrane filtration, and ultrafiltration, and the retained tea soup is ultrafiltered retained tea soup; (S.2) firstly removing large particles trapped in the tea soup by low-speed centrifugation, and then performing high-speed centrifugation to obtain a supernatant containing nano-biomacromolecule-polyphenol composite particles; (S.3) adding a monovalent metal salt to the supernatant to obtain an aqueous phase containing tea soup nanoparticles, wherein the size of the tea soup nanoparticles is less than 20 nm; (S.4) Homogenizing the oil phase and the water phase to obtain the nanoscale Pickering emulsion based on tea soup nanoparticles, wherein the average size of the nanoscale Pickering emulsion is less than 300 nm.

2. The method according to claim 1, characterized in that In the step (S.2), the first centrifugation is performed at a speed of 10,000 g for 15 to 30 minutes to remove large particles trapped in the tea soup; and then the centrifugation is performed at a speed of 36,000 g for 60 to 120 minutes to obtain a supernatant containing nano-biomacromolecule-polyphenol composite particles.

3. The method according to claim 1 or 2, characterized in that The monovalent metal salt in the step (S.3) is a sodium salt or a potassium salt.

4. The method according to claim 3, characterized in that The concentration of the monovalent metal salt in the step (S.3) is 0.3%-1.0%.

5. The method according to claim 1 or 2, characterized in that In the step (S.4), the volume ratio of the oil phase to the water phase is (5-30): (70-95).

6. A nanoscale Pickering emulsion based on tea nanoparticles, characterized in that: The invention discloses a novel nanostructured carbonyl phosphate ...

7. The nanoscale Pickering emulsion based on tea nanoparticles according to claim 6, characterized in that: The polyphenol content in the biomacromolecule-polyphenol composite particles exceeds 10%; and Biomacromolecules include proteins and / or polysaccharides.

8. Use of the nanoscale Pickering emulsion based on tea nanoparticles as claimed in claim 6 or 7 in the preparation of foods, cosmetics and medicines.

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