Antioxidant concentrated Mickering emulsion based on polyphenol and polysaccharide microgel interface assembly and preparation method thereof

Abstract

The present invention provides a preparation method of an antioxidant concentrated Mickering emulsion assembled based on a polyphenol and polysaccharide microgel interface, comprising the following steps: mixing an aqueous phase containing natural polysaccharide microgel with an oil phase uniformly dispersed with water-soluble polyphenols in a mass ratio of 8:2-7:3, shearing at high speed, and obtaining an oil-in-water emulsion; centrifuging the oil-in-water emulsion to remove microgels not adsorbed on the oil-water interface, thereby obtaining a target emulsion; in the oil phase, the content of water-soluble polyphenols is 0.05wt%-0.10wt%. The present invention utilizes the cross-interface diffusion of polyphenols to significantly improve the adsorption performance of polysaccharide microgels at the oil-water interface, thereby greatly improving the stability of the emulsion. The emulsion system also has the advantages of low cost and simple preparation process, can be used for the embedding and delivery of oxidation-sensitive fat-soluble active ingredients, and has broad application prospects in the design and development of nutritionally fortified foods.

Description

Technical Field

[0001] The present invention belongs to the technical field of emulsion preparation, and particularly relates to an antioxidant concentrated Mickering emulsion based on the interfacial assembly of polyphenol and polysaccharide microgels and a preparation method thereof, and also relates to the application of the Mickering emulsion in the food industry. Background Art

[0002] Polysaccharides are an important component of food and are also important food additives in the food industry. Natural polysaccharides have high molecular weight properties and are often used as thickeners, stabilizers, and gelling agents. They are very important for maintaining the stability of food systems. In addition, natural polysaccharides have a variety of health regulatory functions. A large number of studies have confirmed their important role in intestinal flora regulation, obesity prevention, and immune regulation. The increased use of natural polysaccharides in food systems is expected to improve the nutritional structure of industrial foods. However, the insufficient emulsification capacity of natural polysaccharides often limits their use in emulsion foods. Studies have shown that the microgel form of natural polysaccharides has certain emulsifying activity and is suitable for the emerging Mickering emulsification mechanism. However, in practical applications, the stability of polysaccharide-based Mickering emulsions still needs to be improved.

[0003] Chinese patent CN108013475B discloses a polypeptide-polysaccharide composite emulsion and its preparation method, which uses a polypeptide without a pepsin hydrolysis site and a low-ester pectin to prepare an emulsion that is stable in neutral and acidic environments. It can protect functional active ingredients in the gastric digestion environment and achieve targeted delivery function. This case fully demonstrates the important role of polysaccharides in maintaining the digestive stability of emulsions, but the polypeptide with a specific amino acid sequence used therein significantly increases the preparation cost of the emulsion. In addition, compared with protein ingredients, natural polysaccharides have better consumer acceptance and are not restricted in terms of safety (allergens) and religious ethics (animal protein). Therefore, the development of natural polysaccharide-based food emulsifiers has broad market prospects.

[0004] Chinese patent CN116375903B discloses a method for preparing a natural Panax notoginseng polysaccharide and a method for preparing a Pickering emulsion. The polysaccharide raw material used is extracted by boiling Panax notoginseng stems in water to prepare a stable Pickering emulsion. Although the emulsifier used in the method is a natural polysaccharide, which conforms to the emerging consumer concept of clean label, the Panax notoginseng polysaccharide used has not yet been achieved large-scale industrial application and has high development costs. Therefore, how to improve the emulsification properties of commercial natural polysaccharides remains an industry problem that needs to be solved urgently.

[0005] In summary, the development of new natural polysaccharide emulsifiers has broad market prospects, but the natural polysaccharides currently used in the mainstream market have the disadvantage of insufficient emulsification activity. Therefore, establishing new emulsification mechanisms, developing the emulsification activity of popular natural polysaccharide raw materials, and constructing stable food-based emulsions based on natural raw materials are technical challenges that need to be addressed urgently. Summary of the Invention

[0006] One of the objectives of the present invention is to provide a method for preparing an antioxidant concentrated Mickering emulsion based on the interfacial assembly of polyphenols and polysaccharide microgels. The method utilizes the diffusion behavior of water-soluble polyphenols from the oil phase to the water phase to induce microgel aggregation at the interface, thereby achieving the purpose of improving the stability of the polysaccharide microgel emulsion.

[0007] The second object of the present invention is to provide an antioxidant concentrated Mickering emulsion based on the interfacial assembly of polyphenol and polysaccharide microgels with good storage stability and oxidation stability.

[0008] The third object of the present invention is to provide an antioxidant concentrated Mickering emulsion based on the interfacial assembly of polyphenols and polysaccharide microgels for use in the food industry.

[0009] The technical solution adopted by the present invention to achieve one of the objectives is to provide a method for preparing an antioxidant concentrated Mickering emulsion based on the interfacial assembly of polyphenols and polysaccharide microgels, comprising the following steps:

[0010] An aqueous phase containing natural polysaccharide microgels and an oil phase uniformly dispersed with water-soluble polyphenols are mixed in a mass ratio of 8:2-7:3, and subjected to high-speed shearing to induce the natural polysaccharide microgels to aggregate at the oil-water interface by utilizing the cross-interface diffusion behavior of the polyphenols to obtain an oil-in-water emulsion; the oil-in-water emulsion is centrifuged to remove the microgels not adsorbed on the oil-water interface to obtain the target emulsion; the content of the water-soluble polyphenols in the oil phase is 0.05wt%-0.10wt%.

[0011] The present invention provides a method for preparing an antioxidant concentrated Mickering emulsion based on the interfacial assembly of polyphenol and polysaccharide microgels. The overall concept and inventive principle are as follows:

[0012] The present invention is based on scientific problems such as the lack of emulsification activity of natural polysaccharide molecules and the need to improve the emulsification activity of natural polysaccharide microgels, and improves the existing Mickering emulsification mechanism. In the Mickering emulsification mechanism, microgels have a certain interfacial adsorption activity and can form a more stable interfacial layer through interfacial deformation and stretching. However, natural polysaccharide microgels lack a hydrophobic structure, and the adsorption amount at the oil-water interface is still low, making it difficult to maintain the long-term stability of the emulsion. Further studies have found that there is an interaction between polyphenols and polysaccharide microgels, which can trigger clustering between microgels. Based on the above research, the preparation method of the Mickering emulsion provided by the present invention uses water-soluble polyphenols as raw materials, uniformly disperses them in the oil phase, and then utilizes the active diffusion of water-soluble polyphenols from the oil phase to the water phase across the interface to induce the aggregation of natural polysaccharide microgels at the oil-water interface, enhance the mechanical strength of the interfacial layer, and thus significantly improve the stability of the polysaccharide microgel emulsion.

[0013] Conventional emulsion systems typically use polyphenols as antioxidants, increasing the amount of polyphenols to improve the oxidative stability of the emulsion. Unlike this, the present invention imposes certain restrictions on the amount of polyphenols used in order to leverage the cross-interface diffusion behavior of polyphenols, enabling them to fully induce the aggregation of natural polysaccharide microgels at the oil-water interface and achieve a stabilizing effect. When the polyphenol content is too low, the cross-interface behavior is weak and an effective induction effect cannot be achieved. When the polyphenol content is too high, both the amount and speed of diffusion increase, easily leading to the formation of larger aggregates of microgels before reaching the interface, which in turn impairs the stability of the emulsion. In summary, in the present invention, the content of water-soluble polyphenols in the oil phase is controlled to 0.05wt%-0.10wt%.

[0014] Furthermore, the method for preparing the aqueous phase containing the natural polysaccharide microgel comprises mixing the natural polysaccharide macrogel with water in a mass ratio of 1:1-1:2 and dispersing the mixture at a speed of 10,000-12,000 rpm for 10-15 minutes. These dispersion conditions ensure that the polysaccharide microgel has a small size (less than 10 μm) and a uniform particle size distribution.

[0015] Furthermore, in the macroscopic gel of the natural polysaccharide, the mass concentration of the natural polysaccharide is 1.0 wt%-3.0 wt%; the natural polysaccharide includes a combination of one or more of agarose, sodium alginate, pectin, and kappa-carrageenan.

[0016] Preferably, the method for preparing the macro gel of the natural polysaccharide comprises the following steps: dispersing the natural polysaccharide powder in deionized water, forming a homogeneous polysaccharide solution by heating or stirring, and then preparing the natural polysaccharide macro gel by cooling or adding a cross-linking agent. Specifically, according to the type of natural polysaccharide, a suitable preparation method is selected, for example: agarose (cooling-gelation), sodium alginate (Ca 2+ Cross-linking), pectin (Ca 2+ cross-linked), or κ-carrageenan (K + cross-linking).

[0017] Furthermore, in the oil phase in which water-soluble polyphenols are uniformly dispersed, the water-soluble polyphenols include a combination of one or more of tannic acid, tea polyphenols, and proanthocyanidins; and the oil phase includes a combination of one or more of soybean oil, peanut oil, corn oil, and sunflower oil.

[0018] Furthermore, the method for preparing an oil phase uniformly dispersed with water-soluble polyphenols comprises adding the water-soluble polyphenols to the oil phase and dispersing the polyphenols at a rotation speed of 8,000-12,000 rpm for 0.5-1 minute. These dispersion conditions promote uniform dispersion of the polyphenols in the oil phase, ensuring uniform cross-interface diffusion of the polyphenols during the subsequent emulsification stage. Furthermore, controlling the dispersion time to 0.5-1 minute avoids issues such as system temperature increases caused by prolonged shearing, thereby preventing adverse effects on the stability of the polyphenols.

[0019] Furthermore, the aqueous phase containing the natural polysaccharide microgel is mixed with the oil phase in which the water-soluble polyphenols are uniformly dispersed, and high-speed shearing is performed to obtain a stable oil-in-water emulsion. Preferably, the high-speed shearing speed is 8000-12000 rpm and the time is 2-3 minutes.

[0020] Furthermore, by centrifuging the obtained oil-in-water emulsion, a large amount of microgels not adsorbed on the interface are removed, thereby increasing the oil phase ratio of the final emulsion product. Preferably, the centrifugal speed is 1500-2500 rpm and the centrifugal time is 5-10 minutes.

[0021] The technical solution adopted by the present invention to achieve the second purpose is: to provide an antioxidant concentrated Mickering emulsion based on the interface assembly of polyphenols and polysaccharide microgels, which is prepared by the preparation method according to one of the purposes of the present invention.

[0022] In the antioxidant concentrated Mickering emulsion provided by the present invention, water-soluble polyphenols are used to diffuse across the interface from the oil phase to the water phase, inducing the aggregation of polysaccharide microgels at the oil-water interface, enhancing the strength of the microgel interface layer, and achieving significant improvements in the storage stability, oxidation stability, and high-temperature resistance of the emulsion.

[0023] Preferably, the antioxidant concentrated Mickering emulsion contains no less than 40 wt % oil.

[0024] The technical solution adopted by the present invention to achieve the third purpose is to provide an antioxidant concentrated Mickering emulsion based on the interfacial assembly of polyphenols and polysaccharide microgels according to the second purpose of the present invention for use in the food industry.

[0025] Furthermore, the application includes using the antioxidant concentrated Mickering emulsion as a carrier for the encapsulation and delivery of oxidation-sensitive, fat-soluble active ingredients. Preferably, the antioxidant concentrated Mickering emulsion provided by the present invention can be used as a carrier for a variety of active substances, such as unsaturated fatty acids, curcumin, carotene, and other hydrophobic substances for the oral delivery of nutritional supplements.

[0026] Furthermore, in the preparation method of the antioxidant concentrated Mickering emulsion provided by the present invention, the oil phase content is increased to 40 wt% or above by low-speed centrifugation. Compared with conventional carriers, the emulsion provided by the present invention has a higher active ingredient loading capacity.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The present invention provides a method for preparing an antioxidant concentrated Mickering emulsion based on the interfacial assembly of polyphenols and polysaccharide microgels. Water-soluble polyphenols are uniformly dispersed in an oil phase as the dispersed phase, and the polysaccharide microgel dispersion is used as the continuous phase to prepare an oil-in-water emulsion. For the first time, the cross-interfacial diffusion of polyphenols is utilized to induce the aggregation of natural polysaccharide microgels at the oil-water interface, strengthening the polysaccharide microgel interfacial layer and significantly improving the stability of the polysaccharide microgel emulsion.

[0029] (2) The antioxidant concentrated Mickering emulsion prepared by the present invention, based on the interfacial assembly of polyphenol and polysaccharide microgels, has excellent storage stability and oxidative stability, effectively improving the commercial value of the product. Furthermore, the emulsion has the advantages of a simple and efficient production process, low production cost, and environmental safety, making it suitable for industrial production.

[0030] (3) The antioxidant concentrated Mickering emulsion based on the interfacial assembly of polyphenols and polysaccharide microgels prepared by the present invention can be used as an embedding carrier for many active substances, especially functional ingredients that are not resistant to oxidation. The emulsion prepared by the present invention utilizes the cross-interfacial diffusion of polyphenols to induce the aggregation of natural polysaccharide microgels at the oil-water interface, which not only enhances the mechanical strength of the polysaccharide interface layer but also improves the oxidative stability and high-temperature stability of the emulsion. The emulsion showed no obvious demulsification or phase separation after storage at 50°C for 7 days. Its good storage and oxidative stability give it broad promotion and application prospects in the food industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The appearance of the emulsions prepared in Examples 1-3 of the present invention and Comparative Examples 1-3 during storage at 25°C;

[0032] Figure 2 The appearance of the emulsions prepared in Examples 1-3 of the present invention and Comparative Examples 1-3 during storage at 50°C;

[0033] Figure 3 The microscopic morphologies of the emulsions prepared in Examples 1-3 of the present invention and Comparative Examples 1-3 during storage at 25°C and 50°C;

[0034] Figure 4 The oil oxidation stability of the emulsions prepared in Examples 1-3 of the present invention and Comparative Examples 1-3 during storage at 50°C. DETAILED DESCRIPTION

[0035] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0036] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0037] Unless otherwise specified, the reagents used in the Examples and Comparative Examples can be purchased from the market. Instruments used in the Examples and Comparative Examples: Homogenizer model: T18 homogenizer (IkA).

[0038] The present invention provides a method for preparing an antioxidant concentrated Mickering emulsion based on the interfacial assembly of polyphenols and polysaccharide microgels, comprising the following steps:

[0039] Step 1: dissolving a natural polysaccharide powder having gelling ability in deionized water (polysaccharide content of 1.0 wt% to 3.0 wt%), heating or stirring to form a homogeneous polysaccharide solution; and preparing a natural polysaccharide macrogel (first product) by cooling or adding a crosslinking agent.

[0040] Step 2: Deionized water and the polysaccharide macrogel are mixed in a mass ratio of 1:1-1:2, and high-speed shear crushing is performed (10,000-12,000 rpm, 10-15 min) to obtain a natural polysaccharide microgel (second product) with a small size and uniform particle size distribution;

[0041] Step 3: Dispersing the water-soluble polyphenol powder in vegetable oil and high-speed shearing at 8000-12000 rpm for 0.5-1 min to obtain an oil phase (third product) having a polyphenol content of 0.05 wt%-0.10 wt% and being uniformly dispersed;

[0042] Step 4: Add the second product to the third product in a mass ratio of 8:2-7:3, mix, and shear in a high-speed disperser (shear speed of 8000-12000 rpm, shear time of 2-3 min) to complete emulsification to obtain the fourth product.

[0043] Step 5: The fourth product is subjected to low-speed centrifugation (1500-2500 rpm, 5-10 min) to remove a large amount of microgels not adsorbed on the interface, and finally a concentrated emulsion with an oil phase ratio of more than 40 wt% is obtained.

[0044] The present invention will be further described below with reference to specific examples, but they are not intended to limit the present invention.

[0045] The agarose (Aga) used in Examples 1-3 and Comparative Examples 1-3 was purchased from Fujian Ocean Biotechnology Co., Ltd., with a molecular weight of 33.75 kDa; the tannic acid, tea polyphenols, and proanthocyanidins used were all purchased from Shanghai MacLean Biochemical Technology Co., Ltd.

[0046] Example 1

[0047] A method for preparing an antioxidant concentrated Mickering emulsion based on the interfacial assembly of polyphenols and polysaccharide microgels comprises the following steps:

[0048] Step 1: Dissolve agarose (Aga) powder in deionized water at a mass fraction of 1.0 wt%, heat and stir in a 95°C water bath until completely dissolved (magnetic stirring at 500 rpm for 30 min), and then cool at room temperature to form an Aga macrogel;

[0049] Step 2: Deionized water and Aga macrogel were mixed in a mass ratio of 1:1 and subjected to high-speed shear crushing (10,000 rpm × 15 min) to obtain Aga microgel dispersion (average particle size: 4.92 ± 0.04 μm);

[0050] Step 3: Dispersing tannic acid powder in soybean oil at a mass concentration of 0.05 wt%, and high-speed shearing at 12,000 rpm for 0.5 min to obtain soybean oil containing tannic acid and uniformly dispersed therein;

[0051] Step 4: The Aga microgel was mixed with soybean oil containing tannic acid in a mass ratio of 8:2, and the mixture was dispersed at a high speed of 12000 rpm for 2 minutes to prepare an Aga microgel-stabilized oil-in-water emulsion;

[0052] Step 5: The emulsion prepared in step 4 was centrifuged at 2000 rpm for 5 min to obtain a concentrated emulsion with an oil content of 44.13 ± 0.40 wt%.

[0053] Example 2

[0054] A method for preparing an antioxidant concentrated Mickering emulsion based on the interfacial assembly of polyphenols and polysaccharide microgels comprises the following steps:

[0055] Step 1: Aga powder was dissolved in deionized water at a mass fraction of 2.0 wt%, heated in a 95°C water bath with stirring until completely dissolved (magnetic stirring at 750 rpm for 25 min), and then allowed to cool at room temperature to form an Aga macrogel;

[0056] Step 2: Deionized water and Aga macrogel were mixed in a mass ratio of 1:1 and subjected to high-speed shear crushing (12000 rpm × 10 min) to obtain Aga microgel dispersion (average particle size: 4.63 ± 0.05 μm);

[0057] Step 3: Dispersing the tea polyphenol powder in peanut oil at a mass concentration of 0.10 wt%, and high-speed shearing at 10,000 rpm for 0.5 min to obtain peanut oil containing tea polyphenols and uniformly dispersed;

[0058] Step 4: mixing the Aga microgel and peanut oil containing tea polyphenols in a mass ratio of 7.5:2.5, and dispersing at a high speed of 10,000 rpm for 2 minutes to prepare an Aga microgel-stabilized oil-in-water emulsion;

[0059] Step 5: The emulsion prepared in step 4 was centrifuged at 2000 rpm for 5 min to obtain a concentrated emulsion with an oil content of 49.19±0.53 wt%.

[0060] Example 3

[0061] A method for preparing an antioxidant concentrated Mickering emulsion based on the interfacial assembly of polyphenols and polysaccharide microgels comprises the following steps:

[0062] Step 1: Aga powder was dissolved in deionized water at a mass fraction of 3.0 wt%, heated in a 95°C water bath with stirring until completely dissolved (magnetic stirring at 1000 rpm for 20 min), and then allowed to cool at room temperature to form an Aga macrogel;

[0063] Step 2: Deionized water and Aga macrogel were mixed in a mass ratio of 1:1 and subjected to high-speed shear crushing (12000 rpm × 10 min) to obtain Aga microgel dispersion (average particle size: 4.11 ± 0.05 μm);

[0064] Step 3: Dispersing the proanthocyanidin powder in sunflower oil at a mass concentration of 0.08 wt%, and high-speed shearing at 8000 rpm for 1 min to obtain sunflower oil containing proanthocyanidins and uniformly dispersed;

[0065] Step 4: The Aga microgel and sunflower oil containing proanthocyanidins were mixed in a mass ratio of 7:3, and dispersed at a high speed of 8000 rpm for 3 minutes to prepare an Aga microgel-stabilized oil-in-water emulsion;

[0066] Step 5: The emulsion prepared in step 4 was centrifuged at 2000 rpm for 10 min to obtain a concentrated emulsion with an oil content of 59.31 ± 0.62 wt%.

[0067] Example 4

[0068] A method for preparing an antioxidant concentrated Mickering emulsion based on the interfacial assembly of polyphenols and polysaccharide microgels comprises the following steps:

[0069] Step 1: Sodium alginate (Alg) powder was dissolved in deionized water at a mass fraction of 2.0 wt%, stirred until completely dissolved, and then 200 mM CaCl2 (final concentration of 10 mM) was added and allowed to stand at room temperature to form Alg-Ca 2+ Macrogel;

[0070] Step 2: Mix deionized water and Alg-Ca in a mass ratio of 1:1. 2+ The macrogel was mixed and subjected to high-speed shear crushing (11000 rpm×8 min) to obtain Alg-Ca 2+ microgel dispersion (average particle size: 4.31 ± 0.23 μm);

[0071] Step 3: Dispersing tannic acid powder in soybean oil at a mass concentration of 0.06 wt%, and high-speed shearing at 11,000 rpm for 0.5 min to obtain soybean oil containing tannic acid and uniformly dispersed therein;

[0072] Step 4: Add the Alg-Ca 2+ The microgel was mixed with soybean oil containing tannic acid at a mass ratio of 7.5:2.5 and dispersed at a high speed of 11000 rpm for 2 min to prepare Alg-Ca 2+ microgel-stabilized oil-in-water emulsions;

[0073] Step 5: The emulsion prepared in step 4 was centrifuged at 2000 rpm for 5 min to obtain a concentrated emulsion with an oil content of 48.32±0.25 wt%.

[0074] Example 5

[0075] A method for preparing an antioxidant concentrated Mickering emulsion based on the interfacial assembly of polyphenols and polysaccharide microgels comprises the following steps:

[0076] Step 1: Dissolve low-ester pectin (LMP) powder in deionized water at a mass fraction of 2.0 wt%, stir until completely dissolved, then add 200 mM CaCl2 (final concentration of 20 mM), and let it stand at room temperature to form LMP-CaCl2. 2+ Macrogel;

[0077] Step 2: Mix deionized water and LMP-Ca in a mass ratio of 1:1. 2+ The macrogel was mixed and subjected to high-speed shearing (11000 rpm × 8 min) to obtain LMP-Ca 2+ microgel dispersion (average particle size: 4.50 ± 0.08 μm);

[0078] Step 3: Dispersing the tea polyphenol powder in corn oil at a mass concentration of 0.09 wt%, and high-speed shearing at 12,000 rpm for 0.5 min to obtain corn oil containing tea polyphenols and uniformly dispersed;

[0079] Step 4: The LMP-Ca 2+ The microgel was mixed with corn oil containing tea polyphenols at a mass ratio of 8:2 and dispersed at a high speed of 10500 rpm for 2 min to prepare LMP-Ca 2+ microgel-stabilized oil-in-water emulsions;

[0080] Step 5: The emulsion prepared in step 4 was centrifuged at 2000 rpm for 8 min to obtain a concentrated emulsion with an oil content of 53.82±0.35 wt%.

[0081] Example 6

[0082] A method for preparing an antioxidant concentrated Mickering emulsion based on the interfacial assembly of polyphenols and polysaccharide microgels comprises the following steps:

[0083] Step 1: Dissolve κ-carrageenan (Car) powder in deionized water at a mass fraction of 2.0 wt%, heat and stir in a water bath at 85 °C until completely dissolved (magnetic stirring 1000 rpm × 20 min), then add KCl solution (final concentration 60 mM), and let it stand at room temperature to form Car-K +Macrogel;

[0084] Step 2: Mix deionized water and Car-K in a mass ratio of 1:1. + Macrogels were mixed and subjected to high-speed shearing (11000 rpm × 8 min) to obtain Car-K + microgel dispersion (average particle size: 4.18 ± 0.31 μm);

[0085] Step 3: Disperse the proanthocyanidin powder in soybean oil at a mass concentration of 0.07 wt%, and high-speed shear at 9000 rpm for 1 min to obtain soybean oil containing proanthocyanidins and uniformly dispersed;

[0086] Step 4: Place the Car-K + The microgel was mixed with soybean oil containing proanthocyanidins at a mass ratio of 8:2 and dispersed at a high speed of 12000 rpm for 2 min to prepare Car-K + microgel-stabilized oil-in-water emulsions;

[0087] Step 5: The emulsion prepared in step 4 was centrifuged at 2000 rpm for 6 min to obtain a concentrated emulsion with an oil content of 47.53 ± 0.55 wt%.

[0088] Comparative Example 1

[0089] The difference between this comparative example and Example 1 is that the concentration of tannic acid in step 3 is adjusted to 0.00 wt %, and the other conditions and steps remain unchanged.

[0090] Comparative Example 2

[0091] The difference between this comparative example and Example 1 is that the concentration of tannic acid in step 3 is adjusted to 1.00 wt %, and the other conditions and steps remain unchanged.

[0092] Comparative Example 3

[0093] The difference between this comparative example and Example 1 is that the concentration of tannic acid in step 3 is adjusted to 2.00 wt %, and the other conditions and steps remain unchanged.

[0094] Performance Testing

[0095] The emulsions prepared in Examples 1-3 of the present invention and Comparative Examples 1-3 were subjected to performance tests, and the test items included: room temperature storage stability, heat storage stability, microstructure and oxidation stability analysis of the emulsions.

[0096] The analysis of the macroscopic storage stability of the emulsion includes standing the prepared emulsion at 25 ° C for 30 days, taking pictures to record the macroscopic morphology of the emulsion, and observing whether the emulsion has demulsification, flocculation, and emulsion precipitation (such as Figure 1The prepared emulsion was placed at 50°C for 7 days, and the macroscopic morphology of the emulsion was recorded by taking photos to observe whether the emulsion showed any unstable phenomena such as demulsification, flocculation and emulsion separation. Figure 2 shown.

[0097] The microstructure of the emulsion was observed by taking samples of the emulsion stored at 25°C for 0 days and 30 days, and the emulsion stored at 50°C for 4 days and 7 days, respectively. Figure 3 shown.

[0098] The peroxide value test method involves using a constant temperature accelerated test method. The oil microcapsule powder is stored in a 60±1°C forced air drying oven, away from light. The peroxide value is measured every 10 days to determine the oxidation status of the powder sample. Measurement and calculation are performed using an acid-base titration method, in accordance with GB5009.227-2016, the method for determining the peroxide value (POV) in oils and fats.

[0099] The relevant test results are shown in the attached Figure 1-4 .

[0100] In both Examples 1-3 and Comparative Examples 1-3, natural agarose microgel was used as an emulsifier to prepare oil-in-water emulsions, which were then concentrated by centrifugation. Compared to Comparative Examples 1-3, the concentrated emulsions prepared in Examples 1-3 were significantly more stable, with significant demulsification occurring after storage at 25°C for 30 days ( Figure 1 During the hot storage at 50°C, there was no obvious demulsification or phase separation in Examples 1-3 within 7 days ( Figure 2 Meanwhile, the microstructure shows that the particle size of Examples 1-3 remains stable during the heat storage at 50°C (7 days), while Comparative Examples 1-3 show obvious coalescence of oil droplets during the shorter heat storage period (4 days). Figure 3 ).

[0101] Further, Figure 4 The oxidative stability of the emulsions prepared in Examples 1-3 and Comparative Examples 1-3 during storage at 50°C is shown. The POV (peroxide value) values ​​show that the oxidative stability of Examples 1-3 and Comparative Examples 2 and 3 is relatively stable, while the POV of Comparative Example 1 continues to increase during storage, indicating that the use of polyphenols significantly improves the oxidative stability of the emulsion.

[0102] However, it can be noted that the amount of polyphenol added in Examples 1-3 (0.05 wt%-0.10 wt%) is significantly lower than that in Comparative Examples 2 and 3 (1.00 wt%-2.00 wt%), and the stability of the emulsions prepared in Examples 1-3 is significantly higher than that in Comparative Examples 2 and 3, especially during hot storage at 50°C.

[0103] These results indicate that the oxidative stability of the emulsions prepared in Comparative Examples 2 and 3 relies on excess polyphenols, and that this stabilization mechanism cannot guarantee the physical stability of the emulsions. Analysis suggests that the poor thermal stability of Comparative Examples 2 and 3 may be due to the increased amount of polyphenols added. Excessive polyphenols have a higher diffusion capacity and faster diffusion rate in the oil-water mixture, resulting in the polysaccharide microgels forming larger sizes before adsorption at the interface, hindering their assembly at the interface to form a dense, stable interfacial layer, and consequently, failing to maintain optimal stability under high-temperature storage conditions.

[0104] In contrast, in Examples 1-3, by controlling the amount of water-soluble polyphenol added to the oil phase (the amount of polyphenol is controlled to be 0.05wt%-0.10wt% of the oil phase), the interfacial diffusion induces moderate aggregation of agarose microgels at the interface, which helps to build a stable interfacial layer, not only giving the emulsion better oxidative stability, but also significantly improving the physical stability of the emulsion.

[0105] In summary, the present invention provides a method for improving the emulsification properties of polysaccharide microgels through cross-interfacial diffusion of polyphenols, as well as a method for preparing concentrated emulsions, which are particularly effective in improving emulsion stability. This emulsion preparation method not only effectively improves the long-term storage stability and thermal storage stability of the emulsion, but also imparts good oxidative stability. Furthermore, it offers advantages such as low cost and a simple preparation process.

[0106] The above are only preferred embodiments of the present invention and do not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the contents of the present invention specification should be included in the protection scope of the present invention.

Claims

1. A method for preparing an antioxidant concentrated Mickering emulsion based on the interfacial assembly of polyphenols and polysaccharide microgels, characterized in that: The following steps are involved: An aqueous phase containing natural polysaccharide microgels and an oil phase uniformly dispersed with water-soluble polyphenols are mixed in a mass ratio of 8:2-7:3, and subjected to high-speed shearing to induce aggregation of the natural polysaccharide microgels at the oil-water interface by utilizing the cross-interfacial diffusion behavior of the polyphenols, thereby obtaining an oil-in-water emulsion. The oil-in-water emulsion is centrifuged to remove the microgels not adsorbed on the oil-water interface, thereby obtaining a target emulsion. The content of the water-soluble polyphenols in the oil phase is 0.05 wt%-0.10 wt%. The natural polysaccharide includes a combination of one or more of agarose, sodium alginate, pectin, and kappa-carrageenan; and the water-soluble polyphenols in the oil phase uniformly dispersed therein include a combination of one or more of tannic acid, tea polyphenols, and proanthocyanidins.

2. The preparation method according to claim 1, wherein The method for preparing the aqueous phase containing the natural polysaccharide microgel comprises: mixing the natural polysaccharide macrogel with water in a mass ratio of 1:1-1:2, and dispersing the mixture at a rotation speed of 10,000-12,000 rpm for 10-15 minutes.

3. The preparation method according to claim 2, wherein In the macroscopic gel of the natural polysaccharide, the mass concentration of the natural polysaccharide is 1.0 wt%-3.0 wt%.

4. The preparation method according to claim 1, characterized in that The oil phase in which the water-soluble polyphenols are uniformly dispersed comprises a combination of one or more of soybean oil, peanut oil, corn oil and sunflower oil.

5. The preparation method according to claim 1, wherein The method for preparing the oil phase uniformly dispersed with water-soluble polyphenols comprises: adding the water-soluble polyphenols into the oil phase and dispersing the oil phase at a rotation speed of 8000-12000 rpm for 0.5-1 minute.

6. The preparation method according to claim 1, wherein The high-speed shearing speed is 8000-12000 rpm, and the time is 2-3 minutes.

7. The preparation method according to claim 1, wherein The rotation speed of the centrifugal treatment is 1500-2500 rpm, and the time is 5-10 min.

8. An antioxidant concentrated Mickering emulsion based on the interfacial assembly of polyphenol and polysaccharide microgels, prepared by the preparation method according to any one of claims 1 to 7, characterized in that: The antioxidant concentrated Mickering emulsion has an oil content of not less than 40 wt %.

9. An antioxidant concentrated Mickering emulsion based on the interfacial assembly of polyphenols and polysaccharide microgels according to claim 8, wherein the emulsion is used in the food industry, The antioxidant concentrated Mickering emulsion is used as a carrier for embedding and delivering oxidation-sensitive fat-soluble active ingredients.

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