Aqueous two-phase system and preparation method therefor

Abstract

An aqueous two-phase system, using one of glucan and polyethylene oxide as an aqueous dispersed phase, and the other as an aqueous continuous phase. A stabilizer is added and emulsification is performed to obtain the aqueous two-phase system, the stabilizer comprising sodium caseinate and fructose.

Description

Aqueous two-phase emulsion and preparation method thereof Technical Field

[0001] The present application relates to the technical field of new food, cosmetics and pharmaceutical materials, and in particular to a two-phase aqueous emulsion and a preparation method thereof. Background Art

[0002] Many liquid foods in our daily lives, such as milk, cream, and beer, exist in a multiphase form. This multiphase structure is a complex microstructure composed of multiple components and at multiple scales. The microstructure of a food significantly influences its appearance, flavor, texture, taste, digestion, and absorption. Creating a controllable microstructure can help improve food quality. Numerous researchers are currently developing food systems that achieve superior food quality by modifying food formulations and production processes to manipulate molecular interactions and form complex multiphase structures.

[0003] Emulsions, with their easily adjustable two-phase structure, are the preferred choice for constructing food microstructures. Currently, two-phase emulsions for food are primarily composed of oil and water, but the oil phase is unhealthy and can cause product spoilage after oil oxidation. Therefore, the development of healthier and safer two-phase emulsions is crucial.

[0004] Aqueous two phase system (ATPS), also known as all-aqueous system or water-in-water emulsion, is an emulsion formed by two hydrophilic polymers using the principle of thermodynamic incompatibility. No organic solvent is required in the preparation process. It has the advantages of being green and environmentally friendly, simple to prepare, and highly biocompatible. It has been used in technologies such as probiotic encapsulation, industrial production of starch granules, and construction of delivery systems to slow starch absorption. It has also been used in aspects such as simulating organelles and separation and extraction, involving multiple fields such as food, cosmetics, and pharmaceutical preparations.

[0005] However, unlike the two-phase emulsion composed of water and oil, in the aqueous two-phase emulsion, the direct mixture of two hydrophilic polymers cannot be adsorbed on the water-water interface. The extremely low interfacial tension leads to extremely low adsorption energy and is difficult to stabilize. Moreover, the width of the water-water interface is 10 times the width of the water-oil interface, making it impossible for small-sized substances to cross the interface. Based on the above limitations, it is extremely difficult to prepare a stable and controllable aqueous two-phase emulsion. Some studies have attempted to stabilize the emulsion by using tri-embedded polymers whose ends tend to be distributed in the two phases. There are also attempts to stabilize the aqueous two-phase emulsion by using deformed proteins, synthetic polymers, inorganic particles, etc., but their biocompatibility and safety need to be improved.

[0006] Summary of the Invention

[0007] According to various embodiments of the present application, a two-phase aqueous emulsion and a preparation method thereof are provided.

[0008] One embodiment of the present application provides a two-phase aqueous emulsion, wherein one of dextran and polyethylene oxide is an aqueous dispersed phase and the other is an aqueous continuous phase, and a stabilizer is added and emulsified;

[0009] The stabilizers include sodium caseinate and fructose.

[0010] In some embodiments, the aqueous two-phase emulsion has the polyethylene oxide as the aqueous continuous phase and the dextran as the aqueous dispersed phase; the pH of the aqueous two-phase emulsion is about 1-3.

[0011] In some embodiments, the aqueous two-phase emulsion has the polyethylene oxide as the aqueous continuous phase and the dextran as the aqueous dispersed phase; and the pH of the aqueous two-phase emulsion is about 2.

[0012] In some embodiments, the concentration of the dextran in the aqueous two-phase emulsion is about 1 wt % to 5 wt %, and the concentration of the polyethylene oxide in the aqueous two-phase emulsion is about 5 wt % to 10 wt %.

[0013] In some embodiments, the aqueous two-phase emulsion has the dextran as the aqueous continuous phase and the polyethylene oxide as the aqueous dispersed phase; the pH of the aqueous two-phase emulsion is about 5-10.

[0014] In some embodiments, the aqueous two-phase emulsion has the dextran as the aqueous continuous phase and the polyethylene oxide as the aqueous dispersed phase; and the pH of the aqueous two-phase emulsion is about 6.

[0015] In some embodiments, the concentration of the dextran in the aqueous two-phase emulsion is about 8 wt % to 16 wt %, and the concentration of the polyethylene oxide in the aqueous two-phase emulsion is about 1 wt % to 4 wt %.

[0016] In some embodiments, the relative molecular weight of the dextran is about 100,000 to 1,000,000.

[0017] In some embodiments, the relative molecular weight of the ethylene oxide is about 10,000 to 1,000,000.

[0018] In some embodiments, the added amounts of the sodium caseinate and the fructose are both soluble amounts.

[0019] In some embodiments, the concentration of sodium caseinate in the aqueous two-phase emulsion is not less than about 0.16 wt %, and the concentration of fructose in the aqueous two-phase emulsion is not less than about 0.04 wt %.

[0020] In some embodiments, the concentration of sodium caseinate in the aqueous two-phase emulsion is not less than about 1 wt %, and the concentration of fructose in the aqueous two-phase emulsion is not less than about 0.25 wt %.

[0021] In some embodiments, the composition of the aqueous two-phase emulsion further includes a preservative.

[0022] In some embodiments, the concentration of the preservative in the aqueous two-phase emulsion is about 0.15 wt % to 0.25 wt %.

[0023] An embodiment of the present application further provides a method for preparing the aqueous two-phase emulsion as described in any of the above embodiments, comprising the following steps:

[0024] Mixing dextran, polyethylene oxide, and a stabilizer in water to form a mixture; and

[0025] The mixture is emulsified.

[0026] The details of one or more embodiments of the present application are set forth in the following drawings and description. Other features, objects, and advantages of the present application will become apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the conventional technology, the following briefly introduces the drawings required for use in the embodiments or the conventional technology descriptions. Obviously, the drawings described below are merely embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the disclosed drawings without any creative work.

[0028] FIG1 is a microscopic image of droplets of the aqueous two-phase emulsion of Example 1 under different pH conditions (scale bar 20 μm);

[0029] FIG2 shows the diameter change rate of the droplets of the aqueous two-phase emulsion of Example 1 under different pH conditions;

[0030] FIG3 is a microscopic image of droplets of the aqueous two-phase emulsion of Example 2 under different pH conditions (scale bar 20 μm);

[0031] FIG4 shows the diameter change rate of the droplets of the aqueous two-phase emulsion of Example 2 under different pH conditions;

[0032] FIG5 shows the partition coefficient of sodium caseinate in aqueous two-phase emulsion under different pH conditions in Example 3;

[0033] FIG6 shows the stability differences of the aqueous two-phase emulsion of Example 4 under different sodium caseinate concentrations and different fructose concentrations;

[0034] FIG7 is a microscopic image of droplets of the aqueous two-phase emulsion of Example 5 under different salt concentration conditions (scale bar 20 μm);

[0035] FIG8 is a macroscopic image of a droplet of the aqueous two-phase emulsion of Example 6 before and after heating for 2 hours;

[0036] FIG9 is a microscope image and droplet size distribution diagram of the aqueous two-phase emulsion droplets of Example 6 at heating times of 0 h and 1 h (scale bar 20 μm);

[0037] FIG10 is a microscope image and droplet size distribution diagram of the aqueous two-phase emulsion droplets of Example 6 after heating for 2 h and 3 h (scale bar 20 μm);

[0038] FIG11 is a microscope image and droplet size distribution diagram of the aqueous two-phase emulsion droplets of Example 6 after heating for 4 hours (scale bar 20 μm);

[0039] FIG12 is a macroscopic image and a microscopic image of a droplet of the aqueous two-phase emulsion of Example 7 before and after heating (scale bar 20 μm);

[0040] FIG13 is a microscope image of the aqueous two-phase emulsions of Comparative Examples 1 and 2 before and after standing for 2 minutes (scale bar: 20 μm). DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are intended solely for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0043] In this application, "wt%" refers to concentration by weight.

[0044] In this application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0045] An embodiment of the present application provides a double aqueous phase emulsion, which is obtained by adding a stabilizer and emulsifying one of dextran and polyethylene oxide as the aqueous dispersed phase and the other as the aqueous continuous phase; the stabilizer includes sodium caseinate and fructose.

[0046] The applicant has found through research that protein, as a natural polymer, has high biocompatibility. The secondary structure of protein (such as α-helix, β-fold, etc.) affects its flexibility and can also resist external deformation through structural reorganization, thereby affecting the interfacial stability. The research and development and application of two-phase aqueous emulsions based on protein is an important channel for building a stable and controllable two-phase aqueous emulsion system. After screening a large number of proteins, the applicant selected sodium caseinate as a stabilizer. Sodium caseinate is the sodium salt of protein casein. It has abundant raw material sources, low cost, and high nutritional value. Sodium caseinate has self-assembly properties. Adding fructose to a protein-stabilized emulsion can inhibit phase separation by changing the rheological properties of the continuous phase or forming a spatial network structure. Using sodium caseinate and fructose as stabilizers can form a two-phase aqueous emulsion with uniform size, stable and controllable.

[0047] In some embodiments, the aqueous two-phase emulsion comprises polyethylene oxide as the aqueous continuous phase and dextran as the aqueous dispersed phase; the pH of the aqueous two-phase emulsion is approximately 1 to 3. When the pH is approximately 1 to 3, it is lower than the isoelectric point of sodium caseinate, allowing sodium caseinate to distribute more in the aqueous continuous phase composed of polyethylene oxide, resulting in a stable aqueous two-phase emulsion comprising polyethylene oxide as the aqueous continuous phase and dextran as the aqueous dispersed phase. It is understood that the pH of the aqueous two-phase emulsion in this case can be, for example, but not limited to, approximately 1, 1.5, 2, 2.5, 3, and so on.

[0048] In some embodiments, the aqueous two-phase emulsion comprises polyethylene oxide as the aqueous continuous phase and dextran as the aqueous dispersed phase; and the pH of the aqueous two-phase emulsion is about 2.

[0049] In some embodiments, the concentration of dextran in the aqueous two-phase emulsion is about 1 wt% to 5 wt%, and the concentration of polyethylene oxide in the aqueous two-phase emulsion is 5 wt% to 10 wt%. It is understood that in an aqueous two-phase emulsion with polyethylene oxide as the aqueous continuous phase and dextran as the aqueous dispersed phase, the concentration of dextran in the aqueous two-phase emulsion can be any value of about 1 wt% to 5 wt%, for example, it can be arbitrarily selected from about 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, etc., and the concentration of polyethylene oxide in the aqueous two-phase emulsion can be any value of about 5 wt% to 10 wt%, for example, it can be arbitrarily selected from about 5 wt%, 6 wt%, 6.3 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, etc. It is understood that the concentrations of dextran and polyethylene oxide can also be taken as other mass percentage values, as long as the aqueous two-phase emulsion composed of the two has polyethylene oxide as the aqueous continuous phase and dextran as the aqueous dispersed phase.

[0050] In some embodiments, the aqueous two-phase emulsion comprises dextran as the aqueous continuous phase and polyethylene oxide as the aqueous dispersed phase; the pH of the aqueous two-phase emulsion is approximately 5 to 10. When the pH is approximately 5 to 10, it is higher than the isoelectric point of sodium caseinate, allowing sodium caseinate to distribute more in the aqueous continuous phase composed of dextran, resulting in a stable aqueous two-phase emulsion comprising dextran as the aqueous continuous phase and polyethylene oxide as the aqueous dispersed phase. It is understood that the pH of the aqueous two-phase emulsion in this case can be, for example, but not limited to, approximately 5, 6, 7, 8, 9, 10, and so on.

[0051] In some embodiments, the aqueous two-phase emulsion contains dextran as the aqueous continuous phase and polyethylene oxide as the aqueous dispersed phase; the pH of the aqueous two-phase emulsion is about 6.

[0052] In some embodiments, the concentration of dextran in the aqueous two-phase emulsion is about 8 wt % to 16 wt %, and the concentration of polyethylene oxide in the aqueous two-phase emulsion is about 1 wt % to 4 wt %. It is understood that in the aqueous two-phase emulsion with dextran as the aqueous continuous phase and polyethylene oxide as the aqueous dispersed phase, the concentration of dextran in the aqueous two-phase emulsion can be selected from any value between about 8 wt % and 16 wt %, for example, 8 wt %, 9 wt %, 10 wt %, 11 wt %, 12 wt %, 13 wt %, 14 wt %, 15 wt %, 16 wt %, etc., and the concentration of polyethylene oxide in the aqueous two-phase emulsion can be selected from any value between about 1 wt % and 4 wt %, for example, 1 wt %, 1.9 wt %, 2 wt %, 3 wt %, 4 wt %, etc. It is understandable that the mass percentages of dextran and polyethylene oxide can also be taken as other mass percentage values, as long as the combination of the two forms an aqueous two-phase emulsion with dextran as the aqueous continuous phase and polyethylene oxide as the aqueous dispersed phase.

[0053] In some embodiments, the relative molecular weight of dextran is about 100,000 to 1,000,000. In some embodiments, the relative molecular weight of polyethylene oxide is about 10,000 to 1,000,000. The greater the molecular weight of dextran and / or polyethylene oxide, the higher the viscosity, and the more conducive it is to forming a uniform and stable aqueous two-phase emulsion after adding a stabilizer.

[0054] In some embodiments, the amount of stabilizer added is a soluble amount. In the aqueous two-phase emulsion, within the soluble range, the more stabilizer is added, the more conducive it is to the stability of the emulsion.

[0055] In some embodiments, the concentration of sodium caseinate in the aqueous two-phase emulsion is not less than about 0.16 wt %, and the concentration of fructose in the aqueous two-phase emulsion is not less than about 0.04 wt %.

[0056] In some embodiments, the concentration of sodium caseinate in the aqueous two-phase emulsion is not less than approximately 1 wt %, and the concentration of fructose in the aqueous two-phase emulsion is not less than approximately 0.25 wt %, which can ensure that the aqueous two-phase emulsion does not separate into phases when placed at room temperature for approximately 2 days. Furthermore, the state of the droplets in the aqueous two-phase emulsion remains almost unchanged when the aqueous two-phase emulsion is placed at approximately 80° C. for approximately 3 hours.

[0057] In some embodiments, the concentration of sodium caseinate in the aqueous two-phase emulsion is not less than about 10 wt %, and the concentration of fructose in the aqueous two-phase emulsion is not less than about 2.5 wt %, which can ensure that the aqueous two-phase emulsion does not separate for about 150 days at room temperature.

[0058] In some embodiments, the aqueous two-phase emulsion further comprises a preservative. By adding the preservative, bacterial growth in the aqueous two-phase emulsion can be effectively inhibited.

[0059] In some embodiments, the concentration of the preservative in the aqueous two-phase emulsion is about 0.15 wt % to 0.25 wt %.

[0060] In some embodiments, the concentration of the preservative in the aqueous two-phase emulsion is about 0.2 wt %.

[0061] In some embodiments, the preservative may be selected from, for example but not limited to, ProClin 300.

[0062] An embodiment of the present application further provides a method for preparing the aqueous two-phase emulsion as in any of the above embodiments, comprising the following steps:

[0063] Mixing dextran, polyethylene oxide, and a stabilizer in water to form a mixture; and

[0064] The mixture is emulsified.

[0065] It is understandable that the pH range of the emulsion is determined by which of the dextran and polyethylene oxide is the aqueous continuous phase and which is the aqueous dispersed phase. For example, the pH of the emulsion can be adjusted by, but is not limited to, adding HCl or NaOH.

[0066] In some embodiments, the aqueous two-phase emulsion has polyethylene oxide as the aqueous continuous phase and dextran as the aqueous dispersed phase, and the pH of the aqueous two-phase emulsion is adjusted to about 1-3.

[0067] In some embodiments, the aqueous two-phase emulsion has dextran as the aqueous continuous phase and polyethylene oxide as the aqueous dispersed phase, and the pH of the aqueous two-phase emulsion is adjusted to about 5-10.

[0068] When the pH is approximately 1-3, the sodium caseinate in the stabilizer is more distributed in the aqueous continuous phase composed of polyethylene oxide. When the pH is approximately 5-10, the sodium caseinate in the stabilizer is more distributed in the aqueous continuous phase composed of dextran. Within the above pH range, corresponding stable aqueous two-phase emulsions can be obtained. When the pH is approximately 3.5-5, this pH range is close to the isoelectric point of sodium caseinate, which has poor emulsion stability.

[0069] The present application provides an aqueous two-phase emulsion having one of dextran and polyethylene oxide as an aqueous dispersed phase and the other as an aqueous continuous phase. Sodium caseinate and fructose are selected as stabilizers. Sodium caseinate has good biocompatibility and a particle size of approximately 200 nm to 350 nm. It can be stably adsorbed on the water-water interface, greatly improving the stability of the emulsion. The emulsion can remain in phase without separation under long-term storage conditions. By continuously increasing the concentration of sodium caseinate, the stability of the emulsion can be greatly improved. When the concentration of sodium caseinate in the aqueous two-phase emulsion reaches approximately 10 wt% or more and the concentration of fructose is approximately not less than 2.5 wt%, the emulsion can be stable for approximately 150 days or more. The aqueous two-phase emulsion provided by the present application also has certain salt tolerance and high temperature stability. When a small amount of NaCl is added, the stability of the emulsion is not weakened but enhanced. When the emulsion is placed in a high temperature environment, the state of the droplets in the emulsion changes very little.

[0070] The following specific examples further illustrate the double-phase aqueous emulsion of the present application and its preparation method. The following examples are relatively specific, and it is understood that in other embodiments, they are not limited thereto. In the following specific examples, the instruments, reagents, and materials involved, unless otherwise specified, are all conventional instruments, reagents, and materials already available in the prior art and can be obtained through regular commercial channels. The experimental methods, detection methods, etc. involved in the following examples, unless otherwise specified, are all conventional experimental methods and detection methods already available in the prior art.

[0071] In the following specific examples, the molecular weight of dextran is about 500,000; the molecular weight of polyethylene oxide is about 300,000.

[0072] Example 1

[0073] Multiple aqueous two-phase emulsions with dextran (Dex) as the aqueous continuous phase and polyethylene oxide (PEO) as the aqueous dispersed phase were prepared to study the differences in the stability of the aqueous two-phase emulsions under different pH conditions, including the following steps:

[0074] (1) About 2.4 g of dextran, about 0.2 g of sodium caseinate, and about 200 μL of ProClin 300 were added to about 7.4 g of deionized water, and the mixture was mixed by magnetic stirring at a speed of about 1000 r / min. After stirring for about 3 h, a dextran-sodium caseinate aqueous solution was obtained.

[0075] (2) About 0.4 g of polyethylene oxide, about 0.05 g of fructose, and about 200 μL of ProClin 300 were added to about 9.55 g of deionized water, and the mixture was mixed by magnetic stirring at a speed of about 1000 r / min. After thorough stirring for about 3 h, a polyethylene oxide-fructose aqueous solution was obtained.

[0076] (3) Take about 1 mL of the dextran-sodium caseinate aqueous solution in step (1) and about 1 mL of the polyethylene oxide-fructose aqueous solution in step (2), mix them and add them to a 3 mL glass bottle. After sufficient shaking, a two-phase aqueous emulsion is obtained, in which Dex is the aqueous continuous phase and PEO is the aqueous dispersed phase.

[0077] (4) Dividing the aqueous two-phase emulsion prepared in step (3) into multiple portions, and adjusting the pH of each aqueous two-phase emulsion to approximately 2, 3.5, 6, 7, 8, 9, or 10, respectively.

[0078] (5) Testing the emulsion stability of the aqueous two-phase emulsion prepared in step (4) under different pH conditions.

[0079] The test results are shown in Figures 1 and 2. The microscopic image of the emulsion in Figure 1 shows that the aqueous two-phase emulsions prepared at pH values ​​of approximately 6, 7, and 10 were relatively stable, with droplets remaining small even after two days. At a pH of approximately 3.5, the emulsion had poor stabilization, as this pH is near the isoelectric point of sodium caseinate. At a pH of approximately 2, the stability was even poorer, with phase separation occurring after just a few hours.

[0080] Figure 2 shows the change in droplet diameter in aqueous two-phase emulsions at different pH conditions after different storage times, where D0 represents the initial droplet diameter and D represents the droplet diameter at the time of testing. As shown in Figure 2, the average droplet diameter in aqueous two-phase emulsions at different pH values ​​increases to varying degrees over time. At approximately pH 6, the droplet diameter in the aqueous two-phase emulsion changes minimally, indicating that pH 6 is the most stable.

[0081] Example 2

[0082] An aqueous two-phase emulsion with polyethylene oxide (PEO) as the aqueous continuous phase and dextran (Dex) as the aqueous dispersed phase was prepared to study the stability differences of the aqueous two-phase emulsion under different pH conditions, including the following steps:

[0083] (1) About 1.28 g of polyethylene oxide, about 0.2 g of sodium caseinate, and about 200 μL of ProClin 300 were added to about 8.52 g of deionized water, and the mixture was mixed by magnetic stirring at a speed of about 1000 r / min. After thorough stirring for about 3 h, a polyethylene oxide-sodium caseinate aqueous solution was obtained.

[0084] (2) About 0.8 g of glucan, about 0.05 g of fructose, and about 200 μL of ProClin 300 were added to about 9.15 g of deionized water, and the mixture was mixed by magnetic stirring at a speed of about 1000 r / min. After thorough stirring for about 3 h, a glucan-fructose aqueous solution was obtained.

[0085] (3) Take about 1 mL of the polyethylene oxide-sodium caseinate aqueous solution in step (1) and about 1 mL of the dextran aqueous solution in step (2), mix them and add them to a 3 mL glass bottle. After sufficient shaking, a two-phase aqueous emulsion is obtained, in which PEO is the aqueous continuous phase and Dex is the aqueous dispersed phase.

[0086] (4) Dividing the aqueous two-phase emulsion prepared in step (3) into multiple portions, and adjusting the pH of each aqueous two-phase emulsion to approximately 1.5, 2, 3, 3.5, 6, 7, 8, 9, or 10, respectively.

[0087] (5) Testing the emulsion stability of the aqueous two-phase emulsion prepared in step (4) under different pH conditions.

[0088] The test results are shown in Figures 3 and 4. The microscopic image of the emulsion in Figure 3 shows that the aqueous two-phase emulsions prepared at pH values ​​of approximately 1.5 and 2 were relatively stable, with droplets remaining small even after two days. At a pH of approximately 3.5, the emulsion was less stable, as this pH is near the isoelectric point of sodium caseinate. At a pH of approximately 7, the emulsion was slightly more stable than at pH 3.5, but phase separation occurred within less than a day.

[0089] Figure 4 shows the rate of change in droplet diameter in aqueous two-phase emulsions at different pH conditions after different storage times, where D0 represents the initial droplet diameter and D represents the droplet diameter at the time of testing. As shown in Figure 4, over time, the average droplet diameter in the aqueous two-phase emulsions at different pH values ​​increases to varying degrees within the first day. At pH values ​​of approximately 2 and 3, the droplet diameter changes minimally, while at other pH values, the droplet diameter changes significantly. By the second day, the aqueous two-phase emulsions at pH values ​​of 2 and 3 still exhibit stable droplets, while phase separation occurs at other pH values.

[0090] Example 3

[0091] The partition coefficient of sodium caseinate in aqueous two-phase emulsions was studied under different pH conditions.

[0092] (1) About 1.44 g of dextran, about 0.12 g of sodium caseinate, and about 120 μL of ProClin 300 were added to about 4.44 g of deionized water, and the mixture was mixed by magnetic stirring at a speed of about 1000 r / min. After stirring for about 3 h, a dextran-sodium caseinate aqueous solution was obtained.

[0093] (2) About 0.24 g of polyethylene oxide, about 0.03 g of fructose, and about 120 μL of ProClin 300 were added to about 5.73 g of deionized water, and the mixture was mixed by magnetic stirring at a speed of about 1000 r / min. After thorough stirring for about 3 h, a polyethylene oxide-fructose aqueous solution was obtained.

[0094] (3) Take about 1 mL of the dextran-sodium caseinate aqueous solution in step (1) and about 1 mL of the polyethylene oxide-fructose aqueous solution in step (2), mix them and add them to a 3 mL glass bottle. After sufficient shaking, a two-phase aqueous emulsion is obtained, in which Dex is the aqueous continuous phase and PEO is the aqueous dispersed phase.

[0095] (4) Dividing the aqueous two-phase emulsion prepared in step (3) into multiple portions, and adjusting the pH of each aqueous two-phase emulsion to approximately 2, 3, 6, 7, 8, and 10, respectively.

[0096] (5) Testing the partition coefficient of sodium caseinate in the aqueous two-phase emulsion prepared in step (4) under different pH conditions.

[0097] The test results are shown in Figure 5. CP represents the concentration of sodium caseinate in polyethylene oxide (PEO), and CD represents the concentration of sodium caseinate in dextran (Dex). The ratio of the two, CP / CD, is the distribution coefficient. A distribution coefficient greater than 1 indicates that sodium caseinate is more distributed in polyethylene oxide (PEO), while a distribution coefficient less than 1 indicates that sodium caseinate is more distributed in dextran (Dex). As shown in Figure 5, at pH values ​​of approximately 2 and 3, the distribution coefficient is greater than 1, indicating that sodium caseinate is more distributed in polyethylene oxide (PEO). At pH values ​​of approximately 6, 7, 8, and 10, the distribution coefficient is less than 1, indicating that sodium caseinate is more distributed in dextran (Dex).

[0098] Example 4

[0099] Multiple aqueous two-phase emulsions with dextran (Dex) as the aqueous continuous phase and polyethylene oxide (PEO) as the aqueous dispersed phase were prepared to study the stability differences of different casein and fructose concentrations, including the following steps:

[0100] (1) About 0.24 g of dextran, about 0.0032 g of sodium caseinate, and about 20 μL of ProClin 300 were added to about 0.7568 g of deionized water, and the mixture was mixed by magnetic stirring at a speed of about 1000 r / min. After stirring for about 3 h, a polyethylene oxide-sodium caseinate aqueous solution was obtained.

[0101] (2) About 0.04 g of polyethylene oxide, about 0.0008 g of fructose, and about 20 μL of ProClin 300 were added to about 0.9592 g of deionized water, respectively, and mixed by magnetic stirring at a speed of about 1000 r / min. After thorough stirring for about 3 h, a glucan-fructose aqueous solution was obtained.

[0102] (3) The polyethylene oxide-sodium caseinate aqueous solution in step (1) and the dextran-fructose aqueous solution in step (2) were mixed and added to about 3 mL glass bottles, the pH was adjusted to about 6, and after sufficient shaking, a two-phase aqueous emulsion with a sodium caseinate concentration of about 0.16 wt% and a fructose concentration of about 0.04 wt% was obtained, wherein Dex was the aqueous continuous phase and PEO was the aqueous dispersed phase.

[0103] (4) Repeat the above steps and adjust the amount of sodium caseinate and fructose added to prepare aqueous two-phase emulsions with the following sodium caseinate and fructose concentrations: a. sodium caseinate about 0 wt%, fructose about 0 wt%; b. sodium caseinate about 0.16 wt%, fructose about 0.04 wt%; c. sodium caseinate about 0.32 wt%, fructose about 0.08 wt%; d. sodium caseinate about 0.64 wt%, fructose about 0.16 wt% ; e. Sodium caseinate approximately 1.25wt%, fructose approximately 0.31wt%; f. Sodium caseinate approximately 1.88wt%, fructose approximately 0.47wt%; g. Sodium caseinate approximately 2.5wt%, fructose approximately 0.625wt%; h. Sodium caseinate approximately 5wt%, fructose approximately 1.25wt%; i. Sodium caseinate approximately 7.5wt%, fructose approximately 1.9wt%; j. Sodium caseinate approximately 10wt%, fructose approximately 2.5wt%.

[0104] (5) Observe the appearance changes of the aqueous two-phase emulsions with different sodium caseinate concentrations and different fructose concentrations prepared in step (4) over a period of about 150 days.

[0105] The test results are shown in Figure 6. The numerical values ​​in Figure 6 represent the concentration of sodium caseinate. It can be seen that the concentration of sodium caseinate in the aqueous two-phase emulsion increases from about 0 wt% to about 10 wt%, and the concentration of fructose increases from about 0 wt% to about 2.5 wt%. As the concentrations of sodium caseinate and fructose increase, the emulsion can maintain a stable effect without phase separation over a longer period of time. When the mass percentage of sodium caseinate is about 10 wt% and the fructose concentration is about 2.5 wt%, the aqueous two-phase emulsion remains very stable even after about 150 days.

[0106] Example 5

[0107] Preparation of multiple aqueous two-phase emulsions with dextran (Dex) as the aqueous continuous phase and polyethylene oxide (PEO) as the aqueous dispersed phase to study the salt tolerance of the aqueous two-phase emulsions includes the following steps:

[0108] (1) About 0.96 g of dextran, about 0.04 g of sodium caseinate, and about 50 μL of ProClin 300 were added to about 3 g of deionized water, and the mixture was mixed by magnetic stirring at a speed of about 1000 r / min. After stirring for about 3 h, a dextran-sodium caseinate aqueous solution was obtained.

[0109] (2) About 0.16 g of polyethylene oxide, about 0.01 g of fructose, and about 200 μL of ProClin 300 were added to about 3.83 g of deionized water, and the mixture was mixed by magnetic stirring at a speed of about 1000 r / min. After thorough stirring for about 3 h, a polyethylene oxide-fructose aqueous solution was obtained.

[0110] (3) Take about 1 mL of the dextran-sodium caseinate aqueous solution in step (1) and about 1 mL of the polyethylene oxide aqueous solution in step (2), mix them and add them to a 3 mL glass bottle, adjust the pH to about 6, and shake them thoroughly to obtain a two-phase aqueous emulsion, wherein Dex is the aqueous continuous phase and PEO is the aqueous discrete phase.

[0111] (4) Sodium chloride was added to each of the aqueous two-phase emulsions prepared in step (3), and the concentrations of sodium chloride in each of the aqueous two-phase emulsions were controlled to be approximately 0 mM, 25 mM, 50 mM, and 100 mM, respectively.

[0112] The test results are shown in Figure 7. The microscopic image of the emulsion in Figure 7 shows that after adding approximately 100 mM salt, the emulsion becomes unstable due to electrostatic shielding and protein aggregation. However, adding approximately 25 mM and 50 mM sodium chloride does not destabilize the emulsion, demonstrating that the aqueous two-phase emulsion provided in this example has a certain resistance to salt.

[0113] Example 6

[0114] An aqueous two-phase emulsion with dextran (Dex) as the aqueous continuous phase and polyethylene oxide (PEO) as the aqueous dispersed phase was prepared to study the thermal stability of the aqueous two-phase emulsion, including the following steps:

[0115] (1) About 0.24 g of dextran, about 0.02 g of sodium caseinate, and about 20 μL of ProClin 300 were added to about 0.74 g of deionized water, and the mixture was mixed by magnetic stirring at a speed of about 1000 r / min. After stirring for about 3 h, a dextran-sodium caseinate aqueous solution was obtained.

[0116] (2) About 0.04 g of polyethylene oxide, about 0.005 g of fructose, and about 10 μL of ProClin 300 were added to about 0.955 g of deionized water, and the mixture was mixed by magnetic stirring at a speed of about 1000 r / min. After thorough stirring for about 3 h, a polyethylene oxide-fructose aqueous solution was obtained.

[0117] (3) Take about 1 mL of the dextran-sodium caseinate aqueous solution in step (1) and about 1 mL of the polyethylene oxide-fructose aqueous solution in step (2), mix them and add them to a 3 mL glass bottle, adjust the pH to about 6, and shake thoroughly to obtain a two-phase aqueous emulsion, wherein Dex is the aqueous continuous phase and PEO is the aqueous dispersed phase.

[0118] The aqueous two-phase emulsion of step (1) was heated at about 80° C. for one hour, two hours, three hours, and four hours, and the stability change of the aqueous two-phase emulsion at high temperature was tested.

[0119] The test results are shown in Figures 8 to 11. Figure 8 shows macroscopic images of the aqueous two-phase emulsion before and after heating. The macroscopic images in Figure 8 demonstrate no phase separation before and after heating. Microscopic images also show no significant change in droplet size, demonstrating the good thermal stability of the aqueous two-phase emulsion provided in this embodiment. The microscopic images in Figures 9 to 11 show no significant change in droplet size within three hours of heating at approximately 80°C, demonstrating the emulsion's thermal stability.

[0120] Example 7

[0121] An aqueous two-phase emulsion with polyethylene oxide (PEO) as the aqueous continuous phase and dextran (Dex) as the aqueous dispersed phase was prepared to study the thermal stability of the aqueous two-phase emulsion, including the following steps:

[0122] (1) About 0.128 g of polyethylene oxide, about 0.02 g of sodium caseinate, and about 20 μL of ProClin 300 were added to about 0.852 g of deionized water, and the mixture was mixed by magnetic stirring at a speed of about 1000 r / min. After stirring for about 3 h, a polyethylene oxide-sodium caseinate aqueous solution was obtained.

[0123] (2) About 0.08 g of glucan, about 0.005 g of fructose, and about 20 μL of ProClin 300 were added to about 0.915 g of deionized water, and the mixture was mixed by magnetic stirring at a speed of about 1000 r / min. After thorough stirring for about 3 h, a glucan-fructose aqueous solution was obtained.

[0124] (3) Take about 1 mL of the polyethylene oxide-sodium caseinate aqueous solution in step (1) and about 1 mL of the dextran aqueous solution in step (2) respectively, mix them and add them to a about 3 mL glass bottle, adjust the pH to about 2, and shake them thoroughly to obtain a two-phase aqueous emulsion, wherein PEO is the aqueous continuous phase and Dex is the aqueous discrete phase.

[0125] The aqueous two-phase emulsion of step (3) was heated at about 80° C. for three hours to test the stability change of the aqueous two-phase emulsion at high temperature.

[0126] The test results are shown in FIG12 , which shows macroscopic and microscopic images of the aqueous two-phase emulsion before and after heating. As can be seen from the macroscopic image in FIG12 , the emulsion did not undergo phase separation before and after heating, and the microscopic image also showed no significant change in the droplet size in the emulsion, indicating that the aqueous two-phase emulsion provided in this embodiment has good thermal stability.

[0127] Comparative Example 1

[0128] The preparation method of the aqueous two-phase emulsion is basically the same as that of Example 6, except that sodium caseinate is replaced by bovine serum albumin (BSA).

[0129] Comparative Example 2

[0130] The preparation method of the aqueous two-phase emulsion is basically the same as that of Example 6, except that sodium caseinate is replaced by chicken ovalbumin (OVA).

[0131] Figure 13 shows the dispersion of the droplets of the aqueous two-phase emulsions prepared in Comparative Examples 1 and 2 under a microscope. As can be seen from Figure 13, when BSA or OVA is used as stabilizers in the aqueous two-phase emulsions in Comparative Examples 1 and 2, the droplets of the emulsions are large and unstable, and the droplets coalesce after being placed for 2 minutes, indicating that BSA and OVA have poor stabilizing effects on the emulsions.

[0132] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0133] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. Aqueous two-phase emulsion, characterized in that, it is obtained by using one of dextran and polyethylene oxide as the aqueous dispersed phase and the other as the aqueous continuous phase, adding a stabilizer and emulsifying; the stabilizer includes sodium caseinate and fructose.

2. The aqueous two-phase emulsion according to claim 1, characterized in that, the aqueous two-phase emulsion uses the polyethylene oxide as the aqueous continuous phase and the dextran as the aqueous dispersed phase; the pH of the aqueous two-phase emulsion is about 1 to 3.

3. The aqueous two-phase emulsion according to claim 1 or 2, characterized in that, the aqueous two-phase emulsion uses the polyethylene oxide as the aqueous continuous phase and the dextran as the aqueous dispersed phase; the pH of the aqueous two-phase emulsion is about 2.

4. The aqueous two-phase emulsion according to any one of claims 2 to 3, characterized in that, the concentration of the dextran in the aqueous two-phase emulsion is about 1 wt% to 5 wt%, and the concentration of the polyethylene oxide in the aqueous two-phase emulsion is about 5 wt% to 10 wt%.

5. The aqueous two-phase emulsion according to claim 1, characterized in that, the aqueous two-phase emulsion uses the dextran as the aqueous continuous phase and the polyethylene oxide as the aqueous dispersed phase; the pH of the aqueous two-phase emulsion is about 5 to 10.

6. The aqueous two-phase emulsion according to claim 1 or 5, characterized in that, the aqueous two-phase emulsion uses the dextran as the aqueous continuous phase and the polyethylene oxide as the aqueous dispersed phase; the pH of the aqueous two-phase emulsion is about 6.

7. The aqueous two-phase emulsion according to any one of claims 5 to 6, characterized in that, the concentration of the dextran in the aqueous two-phase emulsion is about 8 wt% to 16 wt%, and the concentration of the polyethylene oxide in the aqueous two-phase emulsion is about 1 wt% to 4 wt%.

8. The aqueous two-phase emulsion according to any one of claims 1 to 7, characterized in that, the relative molecular weight of the dextran is about 100,000 to 1,000,000.

9. The aqueous two-phase emulsion according to any one of claims 1 to 8, characterized in that, the relative molecular weight of the ethylene oxide is about 10,000 to 1,000,000.

10. The aqueous two-phase emulsion according to any one of claims 1 to 9, characterized in that, the addition amounts of the sodium caseinate and the fructose are both soluble amounts.

11. The aqueous two-phase emulsion according to any one of claims 1 to 10, characterized in that, the concentration of the sodium caseinate in the aqueous two-phase emulsion is about not less than 0.16 wt%, and the concentration of the fructose in the aqueous two-phase emulsion is about not less than 0.04 wt%.

12. The aqueous two-phase emulsion according to any one of claims 1 to 11, characterized in that, the concentration of the sodium caseinate in the aqueous two-phase emulsion is about not less than 1 wt%, and the concentration of the fructose in the aqueous two-phase emulsion is about not less than 0.25 wt%.

13. The aqueous two-phase emulsion according to any one of claims 1 to 12, characterized in that, the composition of the aqueous two-phase emulsion further includes a preservative.

14. The aqueous two-phase emulsion according to claim 13, characterized in that, The concentration of the preservative in the aqueous two-phase emulsion is about 0.15 wt% to 0.25 wt%.

15. A method for preparing an aqueous two-phase emulsion according to any one of claims 1 to 14, characterized in that, it comprises the following steps: mixing dextran, polyethylene oxide and a stabilizer in water to form a mixture; and emulsifying the mixture.

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