Nanoscale Pickering emulsion based on tea soup nanoparticles as well as preparation method and application of nanoscale Pickering emulsion

Abstract

The invention relates to the technical field of nanotechnology, in particular to a nanoscale Pickering emulsion based on tea soup nanoparticles and a preparation method and application of the nanoscale Pickering emulsion. The nanoscale Pickering emulsion comprises an oil phase and a water phase, the water phase contains tea soup nanoparticles; the tea soup nano-particles are composed of nano biomacromolecule-polyphenol composite particles and dielectric layers, wherein the surfaces of the nano biomacromolecule-polyphenol composite particles are wrapped with the dielectric layers, and the dielectric layers are provided with same charges. The average size of the Pickering emulsion is smaller than 300 nm. The tea soup is adopted as the raw material, introduction of external factors such as metal ions is avoided, and the food safety is improved from the source. Meanwhile, by optimizing the process, polyphenol nanoparticles with the nano size smaller than 20 nm are efficiently separated from the tea soup, the complexity of process parameter control is reduced, meanwhile, preparation of the nanoscale Pickering emulsion is achieved, and the stability and oxidation resistance of the emulsion are improved.

Description

Technical Field

[0001] The 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, emulsion is widely used in many fields such as food, cosmetics, and medicine, especially in terms of emulsifier, preservation, and anti-oxidation. However, the oxidation of oil components in emulsions is a major challenge in their application. Oil oxidation not only causes odor and loss of nutrients in food, but also generates a series of lipid oxidation products, which 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 antioxidant substances, natural polyphenols have become an ideal choice for lipid oxidation inhibition 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 efficiently scavenge free radicals and inhibit lipid oxidation reactions, and has important application value. In recent years, nanoparticles containing polyphenols have been gradually used as antioxidants to stabilize Pickering emulsion systems. As an efficient emulsification technology, Pickering emulsions enhance the stability of the oil-water interface through nanoparticles, showing unique advantages in emulsion systems.

[0004] The existing technology has achieved the stabilization of Pickering emulsion system by polyphenol nanoparticles to a certain extent, but it still faces many challenges in practical application. First of all, 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, in the preparation process of Pickering emulsion, 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 size are prone to emulsion stratification and instability, while particles with smaller particle size 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 for simultaneously preparing 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 by the following technical solutions: In a first aspect, the present invention first provides a nanoscale Pickering emulsion based on tea soup nanoparticles. It includes 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 nanoscale Pickering emulsion is less than 300 nm.

[0007] The nanoscale Pickering emulsion in the present application first utilizes the mutual cooperation between food macromolecules (such as proteins or polysaccharides) and polyphenols to construct nano biomacromolecule-polyphenol composite particles. The nano biomacromolecule-polyphenol composite particles are used as emulsifiers to achieve the mutual mixing of the oil phase and the water phase, and finally form the Pickering emulsion. In this way, compared with the nanoparticle emulsifiers in the prior art with polyphenols and metal ions as the main components, it can effectively avoid the contamination of polyphenol nanoparticles by metal ions.

[0008] However, the present application has found in experiments that the biomacromolecule-polyphenol composite particles are usually rich in hydrogen bond donor groups and hydrogen bond acceptor groups that can be used to form hydrogen bonds, so adjacent particles will also be subject to certain hydrogen bonding, resulting in certain agglomeration. At the same time, since there will also be certain electrostatic effects between adjacent biomacromolecule-polyphenol composite particles, the agglomeration between the biomacromolecule-polyphenol composite particles is aggravated, resulting in the prepared biomacromolecule-polyphenol composite particles having too large a particle size, and particles with larger particle sizes are prone to stratification and instability of the Pickering emulsion.

[0009] Therefore, in response to the above 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 has 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.

[0010] Preferably, the size of the tea soup nanoparticles is less than 20 nm.

[0011] When the tea soup nanoparticle size is less than 20nm, it can be more effectively adsorbed at the oil-water interface in the Pickering emulsion. Because the particles are smaller, there are more particles per unit volume, and a denser adsorption layer can be formed at the interface. This denser adsorption layer is like a more solid "wall" that can better prevent the aggregation of oil droplets.

[0012] At the same time, the repulsive force generated by the charge carried by smaller particles can work within a shorter distance. Since the distance between particles in the emulsion is relatively close, this charge repulsive force is more effective in preventing particle aggregation, thereby further improving the stability of the emulsion, allowing the emulsion to maintain a good dispersion state during long-term storage and complex environmental conditions (such as temperature changes, mechanical vibrations, etc.).

[0013] Preferably, the polyphenol content in the biomacromolecule-polyphenol composite particles exceeds 10%; and Biomacromolecules include proteins and / or polysaccharides.

[0014] Polyphenols are a class of compounds with multiple phenolic hydroxyl groups that can scavenge free radicals by providing hydrogen atoms. In emulsion systems, high levels of polyphenols can effectively prevent the oil phase and other components in the emulsion from being oxidized. Therefore, when the polyphenol content exceeds 10%, the antioxidant properties are significantly improved. In food emulsions, if the oil phase contains unsaturated fatty acids, polyphenols can react with free radicals to prevent the oxidation and rancidity of fatty acids and extend the shelf life of food. In cosmetic emulsions, high levels of polyphenols can resist the damage of free radicals in the environment to the skin and reduce the damage to skin cells caused by free radicals, thereby achieving functions such as reducing the formation of wrinkles and improving skin elasticity.

[0015] In addition, proteins and polysaccharides have good spatial structures and intermolecular interaction capabilities. For example, proteins can interact with polyphenols through hydrogen bonds, van der Waals forces, etc. to form a stable composite structure, thereby achieving functions such as emulsification and moisturizing. Polysaccharides can provide steric hindrance and a certain viscosity to prevent the aggregation of composite particles. Therefore, when proteins and / or polysaccharides are compounded with polyphenols, on the basis of anti-oxidation, they can also achieve functional synergy and comprehensively exert these functions. In addition, proteins and polysaccharides are common components in organisms and have good biocompatibility. When they form composite particles with polyphenols for use in emulsions (such as in the field of biomedicine or food), this biocompatibility can reduce potential toxicity and irritation to the human body.

[0016] In a second aspect, the present invention also provides a method for preparing the nanoscale Pickering emulsion based on tea soup nanoparticles as described above, which comprises the following steps: (S.1) Take tea leaves, add water, boil them, filter and intercept them, and obtain intercepted tea soup; (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; (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 soup nanoparticles; (S.4) Homogenizing the oil phase and the water phase to obtain the nanoscale Pickering emulsion based on tea soup nanoparticles.

[0017] 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. After being intercepted, 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 nanometer-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, and part of the monovalent metal salt can be attached to the surface of the biomacromolecule-polyphenol composite particles, thereby forming a thicker dielectric layer, so that the interfacial repulsion between the particles is enhanced, and a "salt dissolution phenomenon" occurs, which effectively alleviates the aggregation between the particles.

[0018] Preferably, the tea leaves in step (S.1) are fermented tea leaves.

[0019] 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.

[0020] More preferably, the tea leaves in step (S.1) are any one of black tea, green tea, oolong tea and Pu'er tea.

[0021] Preferably, the boiled tea soup in the 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.

[0022] Preferably, in step (S.2), the retained tea soup is treated by a two-step ultracentrifugation method, firstly removing large particles therein by low speed centrifugation, and then treating it by high speed centrifugation, so that the nano-biomacromolecule-polyphenol composite particles enter the supernatant.

[0023] Preferably, the monovalent metal salt in step (S.3) is a sodium salt or a potassium salt.

[0024] Sodium salt or potassium salt can effectively shield the aggregation force between nanoparticles, reduce aggregates, and obtain nanoparticle components with smaller particle size.

[0025] Preferably, the concentration of the monovalent metal salt in the step (S.3) is 0.3%-1.0%.

[0026] Preferably, in the step (S.4), the volume ratio of the oil phase to the water phase is (5-30): (70-95).

[0027] In a third aspect, the present invention also provides the application of the nanoscale Pickering emulsion based on tea soup nanoparticles in the fields of food, cosmetics and medicine.

[0028] Therefore, compared with the traditional method, the present invention has the following technical advantages: (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; (2) Simple and efficient preparation: By optimizing the process, polyphenol nanoparticles with a size less than 20 nm and rich in polyphenols can be efficiently separated from tea soup, reducing the complexity of process parameter control; (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 and enhances the antioxidant properties of lipids. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is an electron microscope image of the tea soup nanoparticles prepared in Example 1.

[0030] Figure 2 This is an electron microscope image of the nanoscale Pickering emulsion stabilized by tea soup nanoparticles in Example 2.

[0031] Figure 3 This is an electron microscope image of the nanoscale Pickering emulsion stabilized by tea soup nanoparticles in Example 3.

[0032] Figure 4 This is an electron microscope image of the nanoscale Pickering emulsion stabilized by tea soup nanoparticles in Example 4.

[0033] Figure 5 This is an electron microscope image of the nanoscale Pickering emulsion stabilized by tea soup nanoparticles in Example 5. DETAILED DESCRIPTION

[0034] The present invention is further described below in conjunction with specific embodiments. Those of ordinary skill in the art will be able to implement the present invention based on these descriptions. In addition, the embodiments of the present invention involved in the following description are generally only embodiments of a part of the present invention, rather than all embodiments. Therefore, based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work should fall within the scope of protection of the present invention.

[0035] Example 1: Preparation of tea soup nanoparticles (1) Weigh 10 g of black tea leaves, with a tea-water ratio of 1:30, heat in an induction cooker water bath to maintain boiling for 10 min, then use 200-mesh gauze to coarsely filter to remove most of the tea leaves, and then pass the filtrate through a 0.45 μm filter membrane. The filtrate is fixed to a 150 mL volumetric flask, and finally the tea soup is ultrafiltered using a hollow cellulose membrane ultrafiltration system (100 kDa) to retain the intercepted tea soup. This step found 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.

[0036] (2) The ultrafiltered tea soup is further processed by ultracentrifugation, with the first step of centrifugation being performed at 10,000 g for 15 to 30 min to remove large particles; the next step is centrifugation at 36,000 g for 60 to 120 min to obtain a supernatant containing nano-biomacromolecule-polyphenol composite particles; and 0.3 to 3.0% sodium chloride salt is further added to the supernatant component to shield the aggregation force between the nanoparticles, break up the aggregates, and obtain a sol containing tea soup nanoparticle components with smaller particle sizes.

[0037] The characterization results are shown in Figure 1 The electron microscopy results showed that the tea soup nanoparticles were less than 20 nm in size, with an average particle size of about 15.8 nm, spherical in shape, and the absolute value of the surface charge was less than 10 mV. Analysis of its plant active ingredients showed that the polyphenol content in the obtained nanoparticles exceeded 10%, and contained proteins, polysaccharides and other ingredients, which shows that the tea soup nanoparticles are composed of biomacromolecules-polyphenols, are natural, and are stable in the food system. The presence of these ingredients also further improves the subsequent emulsification performance and emulsion stability.

[0038] Example 2: Preparation of Nanoscale Pickering Emulsion Stabilized by Tea Nanoparticles 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, and its concentration is about 1%), and a high-speed shearing machine T18DS25 was used to homogenize at 10000-15000 rpm for 3 min to prepare a crude emulsion, and then the crude emulsion was further homogenized by a microfluidizer with a set pressure of 1000 bar and a homogenization number of 3 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 It shows that the average size of the obtained emulsion is less than 300 nm, which is a nanoscale Pickering emulsion.

[0039] Example 3: Preparation of Nanoscale Pickering Emulsion Stabilized by Tea Nanoparticles 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, and its concentration is about 1%), and a high-speed shearing machine T18DS25 was used to homogenize at 10000-15000 rpm for 3 min to prepare a crude emulsion, and then the crude emulsion was further homogenized by a microfluidizer with a set pressure of 1000 bar and a homogenization number of 3 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 It was shown that the average size of the obtained emulsion was less than 250 nm, which was a nanoscale Pickering emulsion.

[0040] Example 4: Preparation of Nanoscale Pickering Emulsion Stabilized by Tea Nanoparticles 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, and its concentration is about 1%), and a high-speed shearing machine T18DS25 was used to homogenize at 10000-15000 rpm for 3 min to prepare a crude emulsion, and then the crude emulsion was further homogenized by a microfluidizer with a set pressure of 1000 bar and a homogenization number of 3 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 It was shown that the average size of the obtained emulsion was less than 350 nm, which was a nanoscale Pickering emulsion.

[0041] Example 5: Preparation of Nanoscale Pickering Emulsion Stabilized by Tea Nanoparticles 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, and its concentration is about 1%), and a high-speed shearing machine T18DS25 was used to homogenize at 10000-15000 rpm for 3 min to prepare a crude emulsion, and then the crude emulsion was further homogenized by a microfluidizer with a set pressure of 1000 bar and a homogenization number of 3 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 It was shown that the average size of the obtained emulsion was less than 500 nm, which was a nanoscale Pickering emulsion.

[0042] Example 6: Comparison of physical stability of tea soup nano-Pickering emulsion, tea soup Pickering emulsion, and conventional emulsion Preparation of tea soup Pickering emulsion: add rapeseed oil in the oil-water volume ratio, i.e. rapeseed oil: intercepted tea soup = 5:95 (intercepted tea soup is the intercepted tea soup finally obtained in step (1) of Example 1), use a high-speed shearing machine T18DS25 to homogenize at 10000-15000 rpm for 3 min to prepare a crude emulsion, and then use a micro jet high-pressure homogenizer to further homogenize the crude emulsion, set the pressure: 1000 bar, homogenize times: 3 times, to obtain a tea soup Pickering emulsion, the particle size of the emulsion droplets is about 13μm. There are nanoparticles of varying sizes in the tea soup (the particle size range is 150-1000 nm), so the emulsion prepared based on it is also a Pickering emulsion.

[0043] Preparation of conventional emulsion: add corresponding volume of rapeseed oil according to the oil-water volume ratio, that is, rapeseed oil: whey protein aqueous solution = 5:95 (the final concentration of whey protein aqueous solution is 1%), wherein the final protein concentration is 1%, and use high-speed shearing machine T18DS25 to homogenize at 10000-15000 rpm for 3 min to prepare a crude emulsion, and then continue to homogenize the crude emulsion with a microjet high-pressure homogenizer, set pressure: 1000 bar, homogenization times: 3 times, to obtain a conventional emulsion stabilized with whey protein isolate as an emulsifier, and the particle size of the emulsion droplets is 8 μm.

[0044] Test Method 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 precipitated from the emulsion after centrifugation was measured, and the centrifugal stability was calculated. The calculation formula is: Centrifugal stability = (W1-W2) / W1*100% 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.

[0045] The obtained emulsion was subjected to centrifugal stability test, and the results are shown in Table 1.

[0046] Table 1 Physical stability of tea soup nano-Pickering emulsion, tea soup Pickering emulsion, and conventional emulsion sample Centrifugal stability (%) Tea Infusion Nano Pickering Lotion 80.0±3.1 Tea Soup Pickering Lotion 56.7±5.8 Regular lotion 64.1±4.3 The centrifugal retention rate of tea soup nano-Pickering emulsion is 80.0±3.1%, showing excellent physical stability. This is because a large number of tea soup nanoparticles with a particle size of less than 20 nm cover the emulsion interface to form a dense coating. The high particle coverage prevents the droplets from agglomerating. In addition, the nano-sized droplets reduce the emulsification effect under the action of gravity. However, the micron-sized tea soup Pickering emulsion will undergo obvious stratification when left to stand naturally, and the physical stability of the emulsion is even worse. This is because there are a large number of tea soup nanoparticles with a particle size greater than 150 nm in an equal volume of tea soup, and there are many large-sized micro-nano aggregates. The prepared tea soup Pickering emulsion has a low particle coverage rate, and the droplets tend to agglomerate to form larger droplets through centrifugal action. The emulsion generated based on it is more prone to emulsion than the nano-sized emulsion, and its physical stability is much worse than that of the nano-sized emulsion. The centrifugal retention rate of the conventional emulsion prepared with whey protein isolate is about 64.1±4.3%, and its physical stability is lower than that of the tea soup nano-Pickering emulsion.

[0047] Example 7 Comparison of oxidation performance of tea soup nano-Pickering emulsion, tea soup Pickering emulsion and conventional emulsion The tea soup nano-Pickering emulsion, tea soup Pickering emulsion and conventional emulsion were placed in a 50°C oven to accelerate the lipid oxidation reaction. The hydroperoxide value (POV) of the oil in the emulsion was determined by the currently valid GB 5009.227-2023, and the malondialdehyde (MDA) generation 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.

[0048] Table 2 POV values ​​of tea soup nano-Pickering emulsion, tea soup Pickering emulsion, and conventional emulsion under oxidation induction Time (days) Tea Soup Nano Pickering Emulsion POV (meq / oil kg) Tea Soup Pickering Lotion 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 Table 3 MDA values ​​of tea soup nano-Pickering emulsion, tea soup Pickering emulsion, and conventional emulsion under oxidation induction Time (days) Tea Soup Nano Pickering Emulsion MDA (mM) Tea Soup 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 The three emulsions all underwent significant lipid oxidation reactions as the storage time increased. The comparison of the oxidation product target hydroperoxide (POV) and malondialdehyde (MDA) production of the three emulsions showed that the tea soup nano-Pickering emulsion had the best oxidation stability. This is because a large number of tea soup nanoparticles covered the surface of the droplets to form a physical barrier, isolating the contact between oxygen and oils and pro-oxidants; in addition, tea soup nanoparticles are a kind of bio-based material that carries antioxidants on its own. The polyphenols on the surface of the particles preferentially react with oxygen, effectively slowing down the oxidation process of oils. The anti-lipid oxidation ability of the tea soup nano-Pickering emulsion is significantly better than that of the micron-sized tea soup Pickering emulsion. This is because the tea soup nanoparticles with a particle size of less than 20 nm have a large specific surface area, and the Pickering emulsion prepared from them has better antioxidant activity. In comparison, the conventional emulsion with whey protein isolate as an emulsifier has the worst oxidation stability, and the degree of oil oxidation is the highest under the same storage time.

[0049] The specific embodiments described herein are merely examples of the spirit of the present invention. A person skilled in the art of the present invention may make various modifications or additions to the specific embodiments described or replace them in a similar manner, but this will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A nanoscale Pickering emulsion based on tea soup nanoparticles, characterized in that: It includes 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 nanoscale Pickering emulsion is less than 300 nm.

2. The nanoscale Pickering emulsion based on tea soup nanoparticles according to claim 1, characterized in that: The size of the tea soup nanoparticles is less than 20 nm.

3. The nanoscale Pickering emulsion based on tea soup nanoparticles according to claim 1 or 2, characterized in that: The polyphenol content in the biomacromolecule-polyphenol composite particles exceeds 10%; and Biomacromolecules include proteins and / or polysaccharides.

4. A method for preparing a nanoscale Pickering emulsion based on tea nanoparticles as claimed in any one of claims 1 to 3, characterized in that: The following steps are involved: (S.1) Take tea leaves, add water, boil them, filter and intercept them, and obtain intercepted tea soup; (S.2) treating the retained tea by ultracentrifugation to remove large particles in the retained tea soup and obtain a supernatant containing nano-biomacromolecule-polyphenol composite particles; (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 soup nanoparticles; (S.4) Homogenizing the oil phase and the water phase to obtain the nanoscale Pickering emulsion based on tea soup nanoparticles.

5. The method according to claim 4, characterized in that The tea leaves in the step (S.1) are fermented tea leaves.

6. The method according to claim 4, characterized in that The filtration and interception in the step (S.1) include gauze filtration, membrane filtration and ultrafiltration in sequence.

7. The method according to claim 4, characterized in that The monovalent metal salt in the step (S.3) is a sodium salt or a potassium salt.

8. The method according to claim 4 or 7, characterized in that: The concentration of the monovalent metal salt in the step (S.3) is 0.3%-1.0%.

9. The method according to claim 4 or 7, characterized in that: In the step (S.4), the volume ratio of the oil phase to the water phase is (5-30): (70-95).

10. Application of the nanoscale Pickering emulsion based on tea soup nanoparticles as claimed in any one of claims 1 to 3 in the fields of food, cosmetics and medicine.

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