Interface in-situ assembled metal-polyphenol network stabilized emulsion and preparation method thereof

Abstract

The invention discloses an interface in-situ assembled metal-polyphenol network stabilized emulsion and a preparation method thereof, and the method comprises the following steps: dissolving polyphenol in a buffer solution to obtain a dispersed phase; adding an oil phase into the dispersed phase, and emulsifying to obtain a primary emulsion; and adding a metal ion solution into the primary emulsion, fully and uniformly mixing, and supplementing a buffer solution to adjust the emulsion to be alkalescent. According to the preparation method, the polyphenol is firstly adsorbed on the surfaces of oil drops by utilizing the affinity characteristic of the polyphenol, and then an interface in-situ assembled metal-polyphenol network is constructed by utilizing the coordination chelation between the polyphenol and metal ions, so that the stability of the emulsion is realized.

Description

Technical Field

[0001] The present invention relates to the field of interface chemistry, in particular to an interface in-situ assembled metal-polyphenol network stabilized emulsion and a preparation method thereof. Background Art

[0002] Metal-phenolic networks (MPNs) are coordination networks constructed by chelating phenols with metal ions. These networks combine the functional properties of metal ions with the high interfacial affinity of phenolic compounds, offering a new strategy for functional surface modification. With the expanding application of emulsion systems in the food and pharmaceutical sectors, research on interfacial stabilization is becoming increasingly in-depth. MPNs, due to their unique stability, biocompatibility, and interfacial activity, are considered promising materials for emulsion engineering in the food industry. However, current applications of MPNs for emulsion stabilization focus on surface modification of other exogenous stabilizers to balance their amphiphilic properties. This typically involves complex surface modification or surfactant adsorption, resulting in complex and time-consuming procedures that are not suitable for large-scale batch production. This one-sided emphasis on the interfacial modification capabilities of MPNs has overlooked their potential as self-assembling building blocks for targeted enrichment at the oil-water interface. Furthermore, presynthesizing MPN particles and then emulsifying them to form emulsions can easily disrupt coordination bonds due to shear forces during the emulsification process, compromising the long-term stability of the emulsion. In summary, existing strategies have neglected the rational application of the inherent properties of MPNs materials, limiting the application of MPNs materials in the field of emulsion systems. Summary of the Invention

[0003] In view of the deficiencies in the art, the purpose of the present invention is to provide an interfacial in situ assembled metal-polyphenol network stabilized emulsion and a preparation method thereof, so that the metal-polyphenol network stabilized emulsion can be directly assembled in situ at the oil-water interface.

[0004] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0005] In a first aspect, an embodiment of the present invention provides a method for preparing an interfacial in situ assembled metal-polyphenol network stabilized emulsion, the method comprising the following steps:

[0006] The polyphenols are dissolved in a buffer solution to obtain a dispersed phase;

[0007] adding the oil phase to the dispersed phase and emulsifying the phase to obtain a primary emulsion;

[0008] Add the metal ion solution to the primary emulsion and mix thoroughly, and add the buffer solution to adjust the emulsion to be weakly alkaline.

[0009] In some embodiments, the polyphenols are selected from tannic acid, gallic acid, catechin, epigallocatechin gallate, tea polyphenols, or a combination of one or more thereof in any proportion.

[0010] In some embodiments, the oil phase is selected from fish oil, corn oil, rapeseed oil, peanut oil, and soybean oil.

[0011] In some embodiments, the metal ion solution is selected from an iron salt, copper salt, zinc salt, manganese salt, aluminum salt or calcium salt solution with a mass volume concentration of 0.1 to 0.5%.

[0012] In some embodiments, the metal ion solution is preferably an aluminum salt or zinc salt solution.

[0013] In some embodiments, the buffer is selected from MOPS buffer, Tris-HCl buffer, or phosphate buffer.

[0014] In some embodiments, the dispersed phase is a polyphenol solution, and the mass volume concentration of the polyphenol solution is 0.5-5.0%.

[0015] In some embodiments, the emulsification process includes: setting the ultrasonic emulsification power to 100-300W and the ultrasonic emulsification time to 1-5 minutes.

[0016] In a second aspect, an embodiment of the present invention provides an interfacial in-situ assembled metal-polyphenol network stabilized emulsion, which is prepared by the above-mentioned method for preparing the interfacial in-situ assembled metal-polyphenol network stabilized emulsion.

[0017] The beneficial effects achieved by one or more embodiments of the present invention are as follows:

[0018] The present invention provides an interfacial in-situ assembled metal-polyphenol network stabilized emulsion and a preparation method thereof. The present invention utilizes the affinity of polyphenols to cause them to first be adsorbed on the surface of oil droplets for emulsification, and then a metal ion solution is added. The coordination and chelation effect between the polyphenols and the metal ions is utilized to construct an interfacial in-situ assembled metal-polyphenol network, effectively avoiding the destruction of MPNs by shear forces during the emulsification process, thereby achieving a uniform and stable emulsion with both the antioxidant properties of polyphenols and the specific functional properties of metal ions. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0020] Figure 1A flow chart of a method for in-situ assembly of a metal-polyphenol network-stabilized emulsion at an interface provided by an embodiment of the present invention;

[0021] Figure 2 A comparison of the appearance and particle size of the MPNs stabilized emulsions formed with different concentrations of tannic acid before and after a 21-day storage period, provided in an embodiment of the present invention;

[0022] Figure 3 The embodiment of the present invention provides the same concentration of tannic acid, different types of metal ions (Fe 3+ , Cu 2+ , Al 3 + , Zn 2+ ) Comparison of the appearance and particle size of the MPNs-stabilized emulsion before and after a 21-day storage period;

[0023] Figure 4 Cryo-electron microscopy images of emulsions stabilized by different MPNs provided in the embodiments of the present invention. DETAILED DESCRIPTION

[0024] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0025] It should be noted that, unless there is any conflict, the features in the following embodiments and implementations may be combined with each other.

[0026] like Figure 1 As shown, the present invention provides a method for preparing an interfacial in-situ assembled metal-polyphenol network stabilized emulsion, the method comprising the following steps:

[0027] Step S1, dissolving polyphenols in a buffer solution to obtain a dispersed phase;

[0028] Step S2, adding the oil phase to the dispersed phase and emulsifying to obtain a primary emulsion;

[0029] Step S3, adding the metal ion solution to the primary emulsion and mixing thoroughly, and supplementing the buffer solution to adjust the emulsion to be weakly alkaline.

[0030] Furthermore, the polyphenols are selected from one or more of tannic acid (TA), gallic acid, catechin, epigallocatechin gallate, and tea polyphenols, in any proportion, with a mass volume concentration of 0.5-5.0%. The oil phase is selected from fish oil, corn oil, rapeseed oil, peanut oil, and soybean oil. The metal ion solution is selected from an iron salt, copper salt, zinc salt, manganese salt, aluminum salt, or calcium salt solution with a mass volume concentration of 0.1-0.5%. The buffer is selected from MOPS buffer, Tris-HCl buffer, or phosphate buffer.

[0031] Furthermore, the emulsification process includes: setting the ultrasonic emulsification power to 100-300W and the ultrasonic emulsification time to 1-5 minutes.

[0032] It should be noted that the present invention provides an interfacial in situ assembled metal-polyphenol network stabilized emulsion and a preparation method thereof. Compared with the traditional method of modifying other exogenous stabilizers through MPNs (i.e., pre-synthesizing MPN particles and then emulsifying), the method of the present invention does not require synergistic action with other surfactants or pre-synthesizing metal polyphenol particles, and thus maximizes the emulsification properties of the MPNs material itself. The present invention utilizes the affinity of polyphenols to first adsorb them on the surface of oil droplets for emulsification, and then adds a metal ion solution. The coordination and chelation between polyphenols and metal ions is used to construct an interfacial in situ assembled metal-polyphenol network, effectively avoiding the destruction of MPNs by shear forces during the emulsification process. The emulsion prepared by the present invention has uniform particle size, excellent storage stability and physical stability, and combines the antioxidant properties of polyphenols with the specific functional properties of metal ions.

[0033] Example 1

[0034] Tannic acid was dissolved in MOPS buffer (0.1 M, pH 7.4) to obtain a tannic acid solution (1.0%, w / v). The tannic acid solution was mixed with fish oil in a 10:1 volume ratio and ultrasonically emulsified at 200W for 1 minute to obtain a primary emulsion. After thorough emulsification, FeCl₃·6H₂O (0.2%, w / v) was added and rapidly shaken to mix thoroughly. The volume ratio of primary emulsion to FeCl₃·6H₂O (0.2%, w / v) was 2-3:1. MOPs buffer was then added to adjust the pH of the system to a slightly alkaline state.

[0035] Example 2

[0036] Compared with Example 1, the only difference is that tannic acid is dissolved in a MOPS buffer system (0.1 M, pH 7.4) to obtain tannic acid solutions with mass volume concentrations (w / v) of 0.5%, 1.5%, 2.0%, 3.0%, 4.0%, and 5.0%, respectively.

[0037] Figure 2 The figure shows the appearance and particle size comparison of the MPNs stabilized emulsion formed by tannic acid with different concentrations of 0.5%, 1.0%, 1.5% and 2.0% before and after 21 days of storage; Figure 2 As shown in (A), the MPNs stabilized emulsions formed by tannic acid at different concentrations of 0.5%, 1.0%, 1.5%, and 2.0% remained uniform and stable after 21 days of storage, without any destabilization phenomena such as oil precipitation and phase separation. Figure 2 As shown in (B), the MPNs-stabilized emulsion formed by tannic acid with a mass volume concentration of 2.0% has the smallest particle size before and after a storage period of 21 days. It is more stable than the MPNs emulsions formed by tannic acid with concentrations of 0.5%, 1.0%, and 1.5%, indicating that the MPNs-stabilized emulsion formed by high-concentration TA has better stability.

[0038] Example 3

[0039] Tannic acid was dissolved in MOPS buffer (0.1 M, pH 7.4) to obtain a tannic acid solution (2.0%, w / v). The tannic acid solution was mixed with fish oil in a 10:1 volume ratio and ultrasonically emulsified at 200W for 1 minute to obtain a primary emulsion. After thorough emulsification, CuCl2·2H2O (0.2%, w / v) was added and rapidly shaken to mix thoroughly. The volume ratio of primary emulsion to CuCl2·2H2O (0.2%, w / v) was 2-3:1. MOPs buffer was then added to adjust the pH of the system to a slightly alkaline state.

[0040] Example 4

[0041] Tannic acid was dissolved in MOPS buffer (0.1 M, pH 7.4) to obtain a tannic acid solution (2.0%, w / v). The tannic acid solution was mixed with fish oil in a 10:1 volume ratio and ultrasonically emulsified at 200W for 1 minute to obtain a primary emulsion. After thorough emulsification, AlCl₃·6H₂O (0.2%, w / v) was added and rapidly shaken to mix thoroughly. The volume ratio of the primary emulsion to AlCl₃·6H₂O (0.2%, w / v) was 2-3:1. MOPs buffer was then added to adjust the pH of the system to a slightly alkaline state.

[0042] Example 5

[0043] Tannic acid was dissolved in MOPS buffer (0.1 M, pH 7.4) to obtain a tannic acid solution (2.0%, w / v). The tannic acid solution was mixed with fish oil in a 10:1 volume ratio and ultrasonically emulsified at 200W for 1 minute to obtain a primary emulsion. After thorough emulsification, ZnCl2 (0.2%, w / v) was added and rapidly shaken to mix thoroughly. The volume ratio of primary emulsion to ZnCl2 (0.2%, w / v) was 2-3:1. MOPs buffer was then added to adjust the pH of the system to a slightly alkaline state.

[0044] Figure 3 The present invention provides the same concentration of tannic acid (2.0%, w / v), different types of metal ions (Fe 3+ , Cu 2+ , Al 3+ , Zn 2+ ) participate in forming the MPNs stabilized emulsion before and after 21 days of storage and the appearance and particle size comparison diagram; Figure 3 From (A) in the figure, we can see that different types of metal ions (Fe 3+ , Cu 2+ , Al 3+ , Zn 2+ ) participated in the formation of MPNs stabilized emulsions were uniform and stable before and after the 21-day storage period, and no stratification occurred. Figure 3 From (B) in the figure, we can see that Al 3+ 、Zn 2+ The particle size change of the MPNs-stabilized emulsion before and after 21 days of storage was relatively small, indicating that Al 3+ 、Zn 2+ Compared with Fe 3+ 、Cu 2+ The emulsion stabilized by MPNs is more stable, indicating that the stability of the emulsion can be improved by changing the type of metal ions.

[0045] Figure 4 Cryo-electron microscopy images of TA / Fe and TA / Zn stabilized emulsions provided in the embodiments of the present invention. Figure 4 As shown, a dense interface layer formed by close stacking can be observed on the droplet surface with high coverage. The image intuitively confirms the adsorption of the MPNs structure on the droplet surface, indicating that the metal polyphenol network structure can effectively stabilize the emulsion.

[0046] Example 6

[0047] Compared with Example 1, the only difference is that the polyphenol is gallic acid, the oil phase is soybean oil, and the buffer is Tris-HCl buffer.

[0048] Example 7

[0049] Compared with Example 1, the only differences are that the polyphenol is catechin, the oil phase is corn oil, and the buffer is phosphate buffer.

[0050] Example 8

[0051] Compared with Example 1, the only difference is that the polyphenol is epigallocatechin gallate, and the oil phase is peanut oil.

[0052] Example 9

[0053] Compared with Example 1, the only difference is that the polyphenol is tea polyphenol and the oil phase is rapeseed oil.

[0054] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the contents disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only.

[0055] It will be understood that the present application is not limited to the exact construction that has been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof.

Claims

1. A method for preparing an interfacial in-situ assembled metal-polyphenol network stabilized emulsion, characterized in that: The method comprises the following steps: The polyphenols are dissolved in a buffer solution to obtain a dispersed phase; adding the oil phase to the dispersed phase and emulsifying the phase to obtain a primary emulsion; Add the metal ion solution to the primary emulsion and mix thoroughly, and add the buffer solution to adjust the emulsion to be weakly alkaline.

2. The method for preparing an interfacial in-situ assembled metal-polyphenol network stabilized emulsion according to claim 1, characterized in that: The polyphenols are selected from one or more of tannic acid, gallic acid, catechin, epigallocatechin gallate, and tea polyphenols in any proportion.

3. The method for preparing an interfacial in-situ assembled metal-polyphenol network stabilized emulsion according to claim 1, characterized in that: The oil phase is selected from fish oil, corn oil, rapeseed oil, peanut oil, and soybean oil.

4. The method for preparing an interfacial in-situ assembled metal-polyphenol network stabilized emulsion according to claim 1, characterized in that: The metal ion solution is selected from iron salt, copper salt, zinc salt, manganese salt, aluminum salt or calcium salt solution with a mass volume concentration of 0.1-0.5%.

5. The method for preparing an interfacial in-situ assembled metal-polyphenol network stabilized emulsion according to claim 4, characterized in that: The metal ion solution is preferably an aluminum salt or zinc salt solution.

6. The method for preparing an interfacial in-situ assembled metal-polyphenol network stabilized emulsion according to claim 1, characterized in that: The buffer is selected from MOPS buffer, Tris-HCl buffer or phosphate buffer.

7. The method for preparing an interfacial in-situ assembled metal-polyphenol network stabilized emulsion according to claim 1, characterized in that: The dispersed phase is a polyphenol solution, and the mass volume concentration of the polyphenol solution is 0.5-5.0%.

8. The method for preparing an interfacial in-situ assembled metal-polyphenol network stabilized emulsion according to claim 1, characterized in that: The emulsification process includes: setting the ultrasonic emulsification power to 100-300W and the ultrasonic emulsification time to 1-5 minutes.

9. An interfacial in-situ assembled metal-polyphenol network stabilized emulsion, characterized in that: The emulsion is prepared by the method for preparing the interfacial in-situ assembled metal-polyphenol network stabilized emulsion according to any one of claims 1 to 8.

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