Tea saponin-based bacteriostatic nano-emulsion as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of nano-emulsions, and particularly relates to a tea saponin-based antibacterial nano-emulsion and a preparation method thereof.The preparation method comprises the following steps that 1, tea saponin is dissolved in water to form a water phase, plant essential oil serves as an oil phase, an emulsifier and the water phase are added into the oil phase, and the mixture is magnetically stirred to be uniform to form a coarse emulsion; wherein the purity of the tea saponin ranges from 30.15% to 99.50%, the rotating speed of magnetic stirring ranges from 140 r / min to 1000 r / min, and the stirring time ranges from 5 min to 120 min; and (2) preparing the crude emulsion into the tea saponin-based antibacterial nano-emulsion in a high-speed shearing or high-pressure homogenizing manner. According to the invention, the retention time and the stable durability of the bacteriostatic plant essential oil are improved through a nano-emulsion embedding technology, the bacteriostatic effect of the bacteriostatic plant essential oil is exerted to the greatest extent by utilizing the bacteriostatic synergistic effect of the tea saponin, meanwhile, the oxidative deterioration rate of the emulsion in different environments is slowed down, and the dosage of the bacteriostatic essential oil is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of nanoemulsions, and particularly relates to a tea saponin-based antibacterial nanoemulsion and a preparation method thereof. Background Art

[0002] Tea saponin, extracted from the residue left after processing camellia seeds, is a pentacyclic triterpenoid saponin compound with antibacterial and synergistic biological activity. It also possesses strong emulsifying, wettability, and dispersibility properties. It is often used as an antibacterial agent, antibacterial synergist, and surfactant in industries such as food, pesticides, aquaculture, chemicals, and construction. The antibacterial and emulsifying properties of tea saponin are positively correlated with its purity, giving it enormous research potential and economic value. Common antibacterial agents on the market, such as carboxin, dimethomorph, valinomycin, cyazofamid, metalaxyl, flupyraclostrobin, and penthiopyrad, often suffer from high toxicity, poor dispersibility, poor fluidity, and severe pollution due to their inherent properties and structures.

[0003] Nanoemulsion technology can effectively embed the oil phase in water and form an emulsion with a nanometer size distribution, which has good solubility, strong dispersibility and fluidity, thereby improving the bioavailability of oily components.

[0004] Numerous studies have reported that most commercially available antibacterial agents suffer from high toxicity, high residue levels, environmental pollution, phytotoxicity, and cost. For example, organophosphorus pesticides and carbamate pesticides are toxic to the nervous systems of humans and animals. While antibacterial products can effectively reduce the incidence of pests and diseases (such as peony rust, bauhinia dieback, rose powdery mildew, and rose black spot), most are derived from synthetic raw materials. No products utilize natural substances as both antibacterial enhancers and surfactants. Natural plant-derived antibacterial essential oils, due to their wide availability, broad-spectrum antibacterial activity, high safety, environmental friendliness, versatility, wide application, and diverse antibacterial mechanisms, have become ideal natural antibacterial agents with broad application prospects and development potential. High-purity tea saponin extracted from natural plants combines excellent antibacterial and synergistic properties with superior surface activity, making it a highly suitable antibacterial enhancer for nanoemulsions. Summary of the Invention

[0005] The present invention aims to prepare an O / W type plant-derived tea saponin-based antibacterial nanoemulsion by nanoemulsion embedding technology, thereby improving the stability, dispersibility and antibacterial property of oil-soluble antibacterial substances.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows: A method for preparing a tea saponin-based antibacterial nanoemulsion comprises the following steps: (1) Tea saponin is dissolved in water to form an aqueous phase, and plant essential oil is used as an oil phase. An emulsifier and an aqueous phase are added to the oil phase, and magnetic stirring is performed to form a crude emulsion; wherein the purity of tea saponin is 30.15% to 99.50%, the speed of magnetic stirring is 140 r / min to 1000 r / min, and the stirring time is 5 min to 120 min; (2) The crude emulsion is prepared into a tea saponin-based antibacterial nanoemulsion by high-speed shearing or high-pressure homogenization.

[0007] The effect of the tea saponin-based compound antibacterial nanoemulsion is related to the particle size and dispersion degree of the antibacterial essential oil in the emulsion. The core component that exerts the antibacterial and synergistic effect in the nanoemulsion is composed of a compound of two substances, tea saponin and antibacterial essential oil. Tea saponin is easily soluble in water but difficult to dissolve in organic solvents, while most antibacterial essential oils are difficult to dissolve in water. If the antibacterial essential oil is directly added to the dispersion medium of the emulsion system, the two will be completely separated due to the difference in solubility, and the antibacterial and synergistic effect cannot be exerted. Therefore, the present invention utilizes a nanoemulsion embedding system with good dispersibility to increase the dispersion area and dispersibility of the antibacterial essential oil at the oil-water interface in the emulsion system, so as to improve the long-term durability and stable dispersibility of the tea saponin-based compound antibacterial nanoemulsion. In this process, the good surface activity and antibacterial and synergistic effect of tea saponin are utilized. Since tea saponin and plant essential oils are both derived from natural plant sources, the product is also guaranteed to be green and environmentally friendly.

[0008] In a preferred example, the ambient temperature of step (1) is 0°C to 50°C.

[0009] In a preferred example, the oil phase is selected from one or a mixture of antibacterial plant essential oils such as thyme essential oil, cinnamon essential oil, oregano essential oil, tea tree essential oil, clove essential oil and litsea cubeba essential oil, and the added amount of the oil phase is 0.05% to 10%.

[0010] In a preferred example, the oil phase is Litsea cubeba essential oil.

[0011] Wherein, in the tea saponin-based antibacterial nanoemulsion, the ratio of the tea saponin base to the antibacterial agent is 1:10 to 10:1.

[0012] In a preferred example, the emulsifier is one or a mixture of Triton X-100, Tween 20, Tween 40, Tween 60, Tween 80, Tween 81, NP-40, and OP-10, and the amount of the emulsifier added is 0% to 20%.

[0013] In a preferred example, in step (2), the rotation speed of the high-speed shearing is 1300 rpm to 12000 rpm, and the shearing time is 1 min to 10 min; the pressure of the high-pressure homogenization is 100 bar to 1200 bar, and the number of homogenization times is 1 to 5 times.

[0014] Based on a general inventive concept, another object of the present invention is to protect a tea saponin-based antibacterial nanoemulsion prepared by the above preparation method, which has an appearance that can be adjusted to be transparent, clear, milky white or light yellow, has an average particle size ranging from 24.57 nm to 858.66 nm, and a dispersion coefficient of 0.01 to 0.68.

[0015] The tea saponin-based antibacterial nanoemulsion has an EC of one or more fungi selected from the group consisting of tea anthracnose pathogen, rice sheath blight pathogen, aflatoxin, Staphylococcus aureus, and Escherichia coli. 50 The range is 0.002mg / L~30.739mg / L.

[0016] The present method improves the stability, dispersibility, and antibacterial properties of antibacterial essential oils by encapsulating them in a tea saponin-based composite antibacterial nanoemulsion. Encapsulating the antibacterial essential oil in the nanoemulsion effectively isolates it from contact with different media in various environments, preventing oxidation and deterioration of the antibacterial essential oil and enhancing its applicability in diverse environments. Furthermore, the use of tea saponin, which functions as both a surfactant and an antibacterial synergist, fully leverages its dual functional properties. Furthermore, varying process conditions and the amount of antibacterial essential oil loaded can adjust the nanoemulsion's appearance, such as color, transparency, average particle size, interfacial tension, and rheological properties. The synergistic effect of the nanoemulsion encapsulation technique and the amount of antibacterial essential oil loaded not only improves the dispersibility and fluidity of the solution system but also increases the contact area between the antibacterial essential oil and the oil-water interface, further enhancing the stability and dispersibility of the system. Ultimately, the prepared tea saponin-based composite antibacterial nanoemulsion significantly increases its retention rate under various environmental conditions, including those in the presence of oxygen, demonstrating excellent stability and tolerance to adverse environments. The tea saponin and antibacterial essential oils used in the present invention are both environmentally friendly, safe, non-toxic, and harmless to the human body. They also self-degrade over time, without polluting the environment. The resulting tea saponin-based antibacterial nanoemulsion can be used in a variety of applications, including food, daily chemical products, cosmetics, and pesticides. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in conjunction with specific embodiments, but the present invention is not limited to these embodiments. It should be noted that, under the premise of not conflicting, the various embodiments described below or the various technical features can be arbitrarily combined to form new embodiments. In the present invention, unless otherwise specified, all parts and percentages are mass units, and the equipment and raw materials used can be purchased from the market or are commonly used in this area. The methods in the following embodiments, if not otherwise specified, are conventional methods in this area.

[0018] As used herein, the terms "comprises," "includes," "contains," or any other variations thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0019] When amount, concentration or other value or parameter is expressed as range, preferred range, or a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when disclosing a range of "1 to 5", the described range should be interpreted as including ranges of "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5" etc. When a numerical range is described in this article, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range.

[0020] Example 1

[0021] A method for preparing a tea saponin-based antibacterial nanoemulsion comprises the following steps: (1) Under the condition of ambient temperature of 25°C, tea saponin was dissolved in water to form an aqueous phase, plant essential oil was used as the oil phase, and Triton X-100 was added to the essential oil of Litsea cubeba. After the aqueous phase and the oil phase were mixed, magnetic stirring was performed to form a crude emulsion. The purity of tea saponin was 99.50%, the speed of magnetic stirring was 600 r / min, and the stirring time was 30 min. Among them, the addition amount of Litsea cubeba essential oil is 3%, the addition amount of Triton X-100 is 10%, and the addition amount of water is 87%; The ratio of tea saponin to Litsea cubeba essential oil is 1:6, and the amount of tea saponin added is 0.5%; (2) The crude emulsion is prepared into a tea saponin-based antibacterial nanoemulsion by high-pressure homogenization; Among them, the pressure of high-pressure homogenization is 520 bar, and the number of homogenization times is 4; The tea saponin-based antibacterial nanoemulsion was clear and transparent in appearance, with an average particle size of 30.45 nm and a dispersion coefficient of 0.09. 50 It is 0.007mg / L.

[0022] Example 2

[0023] A method for preparing a tea saponin-based antibacterial nanoemulsion comprises the following steps: (1) Under the condition of ambient temperature of 25°C, tea saponin was dissolved in water to form an aqueous phase, plant essential oil was used as the oil phase, Triton X-100 was added to oregano essential oil, the aqueous phase and the oil phase were mixed, and then magnetic stirring was performed to form a crude emulsion; wherein, the purity of tea saponin was 72.16%, the speed of magnetic stirring was 680 r / min, and the stirring time was 75 min; Among them, the addition amount of oregano essential oil is 2%, the addition amount of Triton X-100 is 20%, and the addition amount of water is 78%; The ratio of tea saponin to oregano essential oil was 1:10, and the amount of tea saponin added was 0.2%; (2) The crude emulsion is prepared into a tea saponin-based antibacterial nanoemulsion by high-speed shearing; Among them, the high-speed shearing speed is 6000 rpm and the shearing time is 5 min; The tea saponin-based antibacterial nanoemulsion was clear and transparent in appearance, with an average particle size of 75.03 nm and a dispersion coefficient of 0.12. 50 It is 22.445 mg / L.

[0024] Example 3

[0025] A method for preparing a tea saponin-based antibacterial nanoemulsion comprises the following steps: (1) Under the condition of ambient temperature of 5°C, tea saponin was dissolved in water to form an aqueous phase, plant essential oil was used as the oil phase, Tween 80 was added to cinnamon essential oil, the aqueous phase and the oil phase were mixed, and then magnetic stirring was performed to form a crude emulsion; wherein, the purity of tea saponin was 30.15%, the speed of magnetic stirring was 720 r / min, and the stirring time was 25 min; Among them, the addition amount of cinnamon essential oil is 10%, the addition amount of Tween 80 is 8%, and the addition amount of water is 82%; The ratio of tea saponin to cinnamon essential oil is 1:5, and the amount of tea saponin added is 2%; (2) The crude emulsion is prepared into a tea saponin-based antibacterial nanoemulsion by high-pressure homogenization; Among them, the pressure of high-pressure homogenization is 820 bar, and the number of homogenization times is 3; The tea saponin-based antibacterial nanoemulsion was light yellow and translucent in appearance, with an average particle size of 490.7 nm and a dispersion coefficient of 0.46. 50 It is 29.374 mg / L.

[0026] Example 4

[0027] A method for preparing a tea saponin-based antibacterial nanoemulsion comprises the following steps: (1) Under the condition of an ambient temperature of 0°C, tea saponin was dissolved in water to form an aqueous phase, and thyme essential oil was used as the oil phase. After the aqueous phase and the oil phase were mixed, they were evenly stirred by magnetic stirring. The emulsifying property of tea saponin was utilized without adding any additional emulsifier to form a crude emulsion. The purity of tea saponin was 97.44%, the speed of magnetic stirring was 460 r / min, and the stirring time was 30 min. Among them, the addition amount of thyme essential oil is 0.05%, and the addition amount of water is 99.95%; The ratio of tea saponin to thyme essential oil is 10:1, and the amount of tea saponin added is 0.5%; (2) The crude emulsion is prepared into a tea saponin-based antibacterial nanoemulsion by high-pressure homogenization; Among them, the pressure of high-pressure homogenization is 460bar, and the number of homogenization times is 4; The tea saponin-based antibacterial nanoemulsion was clear and translucent in appearance, with an average particle size of 484.57 nm and a dispersion coefficient of 0.44. 50 It is 28.563 mg / L.

[0028] Example 5

[0029] A method for preparing a tea saponin-based antibacterial nanoemulsion comprises the following steps: (1) Under the condition of ambient temperature of 50°C, tea saponin was dissolved in water to form an aqueous phase, plant essential oil was used as the oil phase, emulsifiers OP-10 and Tween 81 were added to the mixture of tea tree essential oil and clove essential oil, the aqueous phase and the compound oil phase were mixed, and then magnetic stirring was performed to form a crude emulsion; wherein, the purity of tea saponin was 82.17%, the speed of magnetic stirring was 150 r / min, and the stirring time was 10 min; Among them, the addition amount of tea tree essential oil is 0.5%, the addition amount of clove essential oil is 1%, the addition amount of OP-10 is 6%, the addition amount of Tween 81 is 4%, and the addition amount of water is 88.5%; The ratio of tea saponin to mixed essential oil is 2:1, and the amount of tea saponin added is 3%; (2) The crude emulsion is prepared into a tea saponin-based antibacterial nanoemulsion by high-speed shearing; Among them, the high-speed shearing speed is 1300 rpm and the shearing time is 5 min; The tea saponin-based antibacterial nanoemulsion was milky white and translucent in appearance, with an average particle size of 706.23 nm and a dispersion coefficient of 0.58. 50 It is 24.714 mg / L.

[0030] Example 6

[0031] A method for preparing a tea saponin-based antibacterial nanoemulsion comprises the following steps: (1) Under the condition of ambient temperature of 15°C, tea saponin was dissolved in water to form an aqueous phase, plant essential oil was used as the oil phase, and emulsifier OP-10 was added to the essential oil of Litsea cubeba. After the aqueous phase and the oil phase were mixed, magnetic stirring was performed to form a crude emulsion. The purity of tea saponin was 92.17%, the speed of magnetic stirring was 150 r / min, and the stirring time was 12 min. Among them, the addition amount of Litsea cubeba essential oil is 5%, the addition amount of OP-10 is 16%, and the addition amount of water is 79%; The ratio of tea saponin to Litsea cubeba essential oil is 1:2, and the amount of tea saponin added is 2.5%; (2) The crude emulsion is prepared into a tea saponin-based antibacterial nanoemulsion by high-speed shearing; Among them, the high-speed shearing speed is 1300 rpm and the shearing time is 5 min; The tea saponin-based antibacterial nanoemulsion was clear and transparent in appearance, with an average particle size of 160.71 nm and a dispersion coefficient of 0.19. 50 It is 8.436 mg / L.

[0032] Comparative Example 1

[0033] The purity of tea saponin was 30.10%. Other conditions and preparation methods were the same as those in Example 1.

[0034] The tea saponin-based antibacterial nanoemulsion was light yellow in appearance, with an average particle size of 454.52 nm and a dispersion coefficient of 0.54. 50 It is 34.126 mg / L.

[0035] Comparative Example 2

[0036] The purity of tea saponin was 95.50%. Other conditions and preparation methods were the same as those in Example 1.

[0037] The tea saponin-based antibacterial nanoemulsion was clear and transparent in appearance, with an average particle size of 33.45 nm and a dispersion coefficient of 0.10. 50 It is 0.314 mg / L.

[0038] Comparative Example 3

[0039] The ambient temperature of step (1) is -2°C, and other conditions and preparation methods are the same as those in Example 1.

[0040] The tea saponin-based antibacterial nanoemulsion had obvious ice residue on the surface. The average particle size was 1814.62 nm and the dispersion coefficient was 2.41. The EC 50 It is 63.935 mg / L.

[0041] Comparative Example 4

[0042] The ambient temperature of step (1) is 52° C., and other conditions and preparation methods are the same as those in Example 1.

[0043] The tea saponin-based antibacterial nanoemulsion was clear and transparent in appearance, with an average particle size of 238.91 nm and a dispersion coefficient of 0.28. 50 It is 37.511 mg / L.

[0044] Comparative Example 5

[0045] The addition amount of the oil phase was 0.04%, and other conditions and preparation methods were the same as those in Example 1.

[0046] The tea saponin-based compound antibacterial emulsion was clear and transparent in appearance, with an average particle size of 39.51 nm and a dispersion coefficient of 0.15. 50 It is 77.813 mg / L.

[0047] Comparative Example 6

[0048] The addition amount of the oil phase was 11%, and other conditions and preparation methods were the same as those in Example 1.

[0049] The tea saponin-based antibacterial nanoemulsion was light yellow and opaque in appearance, with an average particle size of 1138.02 nm and a dispersion coefficient of 1.75. 50 It is 51.474 mg / L.

[0050] Comparative Example 7

[0051] In the tea saponin-based antibacterial nanoemulsion, the ratio of tea saponin to antibacterial essential oil is 0.75:10. Other conditions and preparation methods are the same as those in Example 1.

[0052] The tea saponin-based antibacterial nanoemulsion was clear and transparent in appearance, with an average particle size of 65.99 nm and a dispersion coefficient of 0.19. 50 It is 65.751 mg / L.

[0053] Comparative Example 8

[0054] In the tea saponin-based antibacterial nanoemulsion, the ratio of tea saponin to antibacterial essential oil is 10.5:1. Other conditions and preparation methods are the same as those in Example 1.

[0055] The tea saponin-based compound antibacterial emulsion prepared was a suspension with an average particle size of 2438.35 nm and a dispersion coefficient of 3.31. 50 It is 56.359 mg / L.

[0056] Comparative Example 9

[0057] The addition amount of the emulsifier was 25.5%, and other conditions and preparation methods were the same as those in Example 1.

[0058] The tea saponin-based antibacterial nanoemulsion was milky white in appearance, with an average particle size of 1224.31 nm and a dispersion coefficient of 1.91. 50 It is 38.882 mg / L.

[0059] The present invention improves the retention time, stability and durability of the antibacterial essential oil through nanoemulsion embedding technology. At the same time, tea saponin, which is an antibacterial synergist and surfactant, is loaded to maximize the antibacterial synergistic effect and surface activity of the antibacterial essential oil, and reduces the dosage of the antibacterial essential oil, thereby broadening its application range in the fields of food, medicine, daily chemical products, agriculture, forestry, fishery, animal husbandry, etc., thereby providing a reference for expanding the application of nanoemulsion technology and antibacterial synergistic technology.

[0060] The above embodiments are merely preferred implementations of the present invention. Any simple modifications, amendments, and substitutions made to the above embodiments based on the technical essence of the present invention fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a tea saponin-based antibacterial nanoemulsion, characterized in that: The steps include: (1) Tea saponin is dissolved in water to form an aqueous phase, and plant essential oil is used as an oil phase. An emulsifier and an aqueous phase are added to the oil phase, and magnetic stirring is performed to form a crude emulsion; wherein the purity of tea saponin is 30.15% to 99.50%, the speed of magnetic stirring is 140 r / min to 1000 r / min, and the stirring time is 5 min to 120 min; (2) The crude emulsion is prepared into a tea saponin-based antibacterial nanoemulsion by high-speed shearing or high-pressure homogenization.

2. The method for preparing a tea saponin-based antibacterial nanoemulsion according to claim 1, characterized in that: The ambient temperature of step (1) is 0°C to 50°C.

3. The method for preparing a tea saponin-based antibacterial nanoemulsion according to claim 1, characterized in that: The oil phase is selected from one or a mixture of antibacterial plant essential oils such as thyme essential oil, cinnamon essential oil, oregano essential oil, tea tree essential oil, clove essential oil and litsea cubeba essential oil, and the addition amount of the oil phase is 0.05% to 10%.

4. The method for preparing a tea saponin-based antibacterial nanoemulsion according to claim 1, characterized in that In the tea saponin-based antibacterial nanoemulsion, the ratio of tea saponin to antibacterial essential oil is 1:10 to 10:

1.

5. The method for preparing a tea saponin-based antibacterial nanoemulsion according to claim 1, characterized in that: The emulsifier is one or a mixture of Triton X-100, Tween 20, Tween 40, Tween 60, Tween 80, Tween 81, NP-40, and OP-10, and the added amount of the emulsifier is 0% to 20%.

6. The method for preparing a tea saponin-based antibacterial nanoemulsion according to claim 1, characterized in that: In step (2), the rotation speed of the high-speed shearing is 1300 rpm to 12000 rpm, and the shearing time is 1 min to 10 min; the pressure of the high-pressure homogenization is 100 bar to 1200 bar, and the number of homogenizations is 1 to 5 times.

7. A tea saponin-based antibacterial nanoemulsion prepared by the preparation method according to any one of claims 1 to 6, characterized in that: The appearance can be controlled to be transparent, milky white or light yellow, the average particle size ranges from 24.57nm to 858.66nm, and the dispersion coefficient is 0.01 to 0.

68.

8. An application of a tea saponin-based antibacterial nanoemulsion prepared by the preparation method according to any one of claims 1 to 6, characterized in that: EC for one or more of the following fungi: Colletotrichum oleifera, Rhizoctonia solani, Aspergillus flavus, Staphylococcus aureus, and Escherichia coli 50 The range is 0.002mg / L~30.739mg / L.