Starch-myricetin composite nanoparticle stabilized Pickering emulsion and preparation method thereof

Abstract

The invention discloses a Pickering emulsion with stable starch-myricetin composite nanoparticles and a preparation method of the Pickering emulsion, and belongs to the technical field of starch modification and emulsion delivery. Starch and myricetin are combined and compounded, a dynamic high-pressure microjet homogenization technology is introduced, the starch-myricetin composite nano-particles capable of stabilizing Pickering emulsion are obtained through a one-step method, and the application limitation that nano-starch is high in hydrophilicity, high in digestibility and the like is effectively solved; the prepared starch-myricetin composite nanoparticles have the characteristics of high stability and slow digestion function; the Pickering emulsion is prepared by further matching with a compound oil phase of coconut oil and cinnamon essential oil, so that the problem of coconut oil solidification can be effectively solved, and the Pickering emulsion has an antibacterial effect.

Description

Technical Field

[0001] This invention belongs to the field of starch modification and emulsion delivery technology, specifically relating to a starch-myricetin composite nanoparticle-stabilized Pickering emulsion and its preparation method. Background Technology

[0002] Coconut oil is a natural oil extracted from coconut meat. It has a long history of use in tropical regions and is primarily composed of medium-chain fatty acids, with lauric acid being the most abundant, exceeding 50%. In addition, coconut oil contains vitamins, polyphenols, phytosterols, and other active substances, exhibiting antioxidant, anti-inflammatory, and anti-thrombotic effects. However, coconut oil has a melting point of only 25–27°C, easily solidifies at room temperature, is not easily flowable, and has poor water solubility, greatly limiting its widespread application in the food industry.

[0003] Cinnamon essential oil is extracted from cinnamon bark, twigs, and leaves. It contains various active substances such as cinnamaldehyde and cinnamyl alcohol, and has excellent antibacterial properties, meeting the requirements for food preservation and functional products. However, cinnamon essential oil has a strong odor, is volatile, and has poor stability. Direct application in actual production can easily lead to its deterioration, and it is difficult to stably bind with oil-based carriers.

[0004] The core of pickering emulsion preparation lies in the selection and preparation of stabilizer particles, mainly including inorganic particles, organic particles, and synthetic particles. Among these, synthetic and inorganic particles may pose certain biosafety concerns; therefore, organic particles are more favored. Natural cassava starch, due to its wide availability, low cost, and good biocompatibility, is widely used in food processing. However, its large size, limited functional properties, and weak interfacial activity as a stabilizer restrict its application in functional food delivery and highly stable emulsion systems.

[0005] Nanotechnology can significantly refine the size of cassava starch, expose a large number of active hydroxyl groups, increase the specific surface area, and exhibit excellent physicochemical properties, overcoming the shortcomings of traditional starch. However, many studies have shown that while the promotion of nanotechnology improves the hydrophilicity and digestibility of starch, it limits its slow digestion and emulsification functions, resulting in some functional imbalances. Therefore, further optimization of the preparation process for nano-starch is still needed. Summary of the Invention

[0006] The purpose of this invention is to provide a starch-myricetin composite nanoparticle-stabilized Pickering emulsion and its preparation method. By modifying starch with myricetin and introducing dynamic high-pressure microfluidic homogenization technology, starch-myricetin composite nanoparticles capable of stabilizing the Pickering emulsion are obtained.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] One of the technical solutions of this invention is to provide a method for preparing a starch-myricetin composite nanoparticle-stabilized Pickering emulsion, comprising the following steps:

[0009] Starch is pulverized to obtain starch micro powder. The starch micro powder is made into a suspension and then dropped into an alcohol solution containing myricetin. The reaction is carried out in the dark and then subjected to dynamic high-pressure microfluidic homogenization. After that, it is freeze-dried to obtain starch-myricetin composite nanoparticles.

[0010] The starch-myricetin composite nanoparticles were made into a suspension, emulsified with a composite oil phase of coconut oil and cinnamon essential oil, and then subjected to dynamic high-pressure microfluidic homogenization to obtain a stable Pickering emulsion of the starch-myricetin composite nanoparticles.

[0011] Alternatively, the starch used may be tapioca starch.

[0012] Preferably, the particle size of the starch powder is 20–50 μm.

[0013] Preferably, the myricetin used accounts for 2% of the mass of the starch powder used.

[0014] Preferably, the stirring speed for the light-protected reaction is 500 r / min, and the time is 8 min.

[0015] Preferably, when preparing starch-myricetin composite nanoparticles, the pressure of the dynamic high-pressure microjet homogenization is 150 MPa, and the number of times is 1.

[0016] Preferably, the mass fraction of the starch-myricetin composite nanoparticle suspension is 1.0%.

[0017] Preferably, the mass ratio of coconut oil to cinnamon essential oil is 1:1.

[0018] Preferably, the volume ratio of the starch-myricetin composite nanoparticle suspension to the composite oil phase is 85:15.

[0019] Preferably, the emulsification shear rate is 10000 r / min, the shearing time is 3 min, and the shearing emulsification is performed 3 times.

[0020] Preferably, when homogenizing the emulsion product, the dynamic high-pressure microjet homogenization pressure is 150 MPa, and the number of times is 5.

[0021] The second technical solution of the present invention provides a starch-myricetin composite nanoparticle-stabilized Pickering emulsion prepared according to the above-mentioned method for preparing a starch-myricetin composite nanoparticle-stabilized Pickering emulsion.

[0022] The third technical solution of the present invention provides an application of the above-mentioned starch-myricetin composite nanoparticle-stabilized Pickering emulsion in food preservation.

[0023] The beneficial technical effects of the present invention are as follows:

[0024] This invention utilizes a combination of starch and myricetin, along with dynamic high-pressure microfluidic homogenization technology, to obtain starch-myricetin composite nanoparticles capable of stabilizing Pickering emulsions in a single step. This results in starch-myricetin composite nanoparticles exhibiting high stability and slow digestibility, effectively overcoming application limitations such as the strong hydrophilicity and high digestibility of nano-starch. The use of myricetin is crucial; it enhances the hydrophobicity and emulsion stability of the nano-starch particles. Under optimal dynamic high-pressure microfluidic homogenization parameters (150 MPa), the starch-myricetin composite nanoparticle emulsion maintains high stability throughout its storage period. The introduction of dynamic high-pressure microfluidic homogenization technology not only enables nano-sized composite particles (particle size 65.36–91.67 nm) but also promotes the binding force between starch and myricetin, resulting in a more compact structure for both.

[0025] This invention utilizes optimized starch-myricetin composite nanoparticles combined with a composite oil phase of coconut oil and cinnamon essential oil to prepare a Pickering emulsion that effectively solves the problem of coconut oil coagulation. During a 30-day storage period, the coconut oil in the prepared Pickering emulsion remains stably dispersed without coagulation or stratification. Furthermore, the introduction of cinnamon essential oil gives the Pickering emulsion significant antibacterial properties, exhibiting marked inhibitory effects against both pathogenic bacteria (e.g., Escherichia coli and Staphylococcus aureus) and putrefactive bacteria (e.g., Pseudomonas aeruginosa). Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 SEM images of the TS used in Example 1, the MTS prepared therefrom, and the cassava starch nanoparticles prepared under various homogenization pressures in Example 2.

[0028] Figure 2 The particle size measurement results of TS used in Example 1 are shown.

[0029] Figure 3 The particle size measurement results are for the MTS prepared in Example 1.

[0030] Figure 4 The particle size measurements are for the nanoparticles prepared under various homogeneous pressures in Examples 2(a) and 3(b).

[0031] Figure 5 The images show SEM images of the TS used in Example 1, the MTS prepared therefrom, the MY used in Example 3, and the cassava starch-myricetin composite nanoparticles prepared under various homogenization pressures in Example 3.

[0032] Figure 6 The results are the RDS, SDS, and RS test results for the digestibility of TS used in Example 1, the prepared MTS, and the cassava starch nanoparticles prepared under various homogenization pressures in Example 2.

[0033] Figure 7 The results of RDS, SDS, and RS tests are for the digestibility of TS used in Example 1, the prepared MTS, and the cassava starch-myricetin composite nanoparticles prepared under various homogenization pressures in Example 3.

[0034] Figure 8 The results show the starch digestibility test results of the TS used in Example 1, the MTS prepared therefrom, and the cassava starch nanoparticles prepared under various homogenization pressures in Example 2.

[0035] Figure 9 The results show the starch digestibility test results of the TS used in Example 1, the MTS prepared therefrom, and the cassava starch-myricetin composite nanoparticles prepared under various homogenization pressures in Example 3.

[0036] Figure 10 The results show the emulsification properties of the TS used in Example 1, the MTS prepared therefrom, and the cassava starch nanoparticles prepared under various homogenization pressures in Example 2.

[0037] Figure 11 The results show the emulsification properties of the cassava starch-myricetin composite nanoparticles prepared under various homogenization pressures in Example 3.

[0038] Figure 12 The results show the myricetin composite rate of the cassava starch-myricetin composite nanoparticles prepared under various homogeneous pressures in Example 3.

[0039] Figure 13 The results show the myricetin complexation rate of the cassava starch-myricetin composite nanoparticles prepared under various homogeneous pressures in Example 3.

[0040] Figure 14Optical microscope magnification of Pickering emulsions prepared with different mass fractions of starch solution, different proportions of composite oil phase, and different dynamic high-pressure microfluidic homogenization times.

[0041] Figure 15 Macroscopic diagrams of Pickering emulsions prepared with different mass fractions of starch solution, different proportions of composite oil phase, and different dynamic high-pressure microjets for homogenization.

[0042] Figure 16 The particle size (a) and zeta potential (d) of Pickering emulsions prepared with starch solutions of different mass fractions in Example 4, the particle size (b) and zeta potential (e) of Pickering emulsions prepared with different dynamic high-pressure microjet homogenization times, and the particle size (c) and zeta potential (f) of Pickering emulsions prepared with different composite oil phase ratios are shown.

[0043] Figure 17 The images are magnified by an optical microscope of the Pickering emulsion prepared under the optimal conditions in Example 4 and placed in the dark for different times.

[0044] Figure 18 The results of antibacterial culture of the Pickering emulsions prepared under the optimal preparation conditions of Example 4 and Comparative Examples 1-2 are shown. Detailed Implementation

[0045] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0046] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0047] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0048] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0049] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0050] Unless otherwise specified, room temperature in this invention refers to a temperature of 20±10℃.

[0051] The testing methods used in this invention are as follows:

[0052] 1. Particle size determination

[0053] Method for determining the particle size of nanoscale particles: The particles to be tested were diluted and mixed evenly with ultrapure water at a ratio of 1g:100mL. The diluted solution was then transferred to the particle size cell and the potential cell for detection. Each sample was tested three times. The temperature was set at 25℃, and the refractive index and viscosity of water were 1.3303 and 0.8903 mPa·s, respectively.

[0054] Methods for determining the particle size of micron-sized particles and emulsions: The particle size of emulsions and micron-sized particles (TS and MTS) was determined using a laser particle size analyzer, and the results are presented as particle size distribution diagrams and average particle size.

[0055] 2. Apparent structure

[0056] Methods: Starch granules were fixed onto a metal stage using conductive adhesive, excess powder was blown away, and the surface was coated with gold to make it conductive. The granules were then observed and analyzed under a scanning electron microscope at 30 kV. For the pickingering emulsion, 10 μL of the emulsion was dropped onto a glass slide, covered with a coverslip, and observed under 40x magnification using an optical microscope to assess droplet size and aggregation.

[0057] 3. Digestibility

[0058] Method: 300 mg of the test particles were placed in a 50 mL sample bottle, and 18 mL of sodium acetate buffer solution (0.2 M, pH=5.2) was added. The mixture was then incubated in a boiling water bath for 15 min. After cooling to room temperature, the mixture was equilibrated in a shaking water bath at 37 °C and 150 rpm for 10 min. Then, 0.5 mL of a mixed enzyme solution (0.1 g α-saccharifying enzyme and 0.05 g α-amylase dissolved in 20 mL of sodium acetate buffer solution) was added to begin digestion. At reaction times of 0, 20, 40, 60, 80, 100, 120, 160, and 180 min, 0.1 mL of the supernatant was collected and 0.9 mL of anhydrous ethanol was added to inactivate the enzyme. The release of glucose was quantified using the GOPOD kit. 10 μL of the enzyme-inactivating sample solution was placed in an ELISA plate, and then 170 μL of reagent one and 20 μL of reagent two were added. After mixing well, the absorbance was measured at 520 nm. Each sample was measured in triplicate and the average value was taken.

[0059] Rapidly digestible starch RDS (%) = (G) 20 -G0)×0.9÷s×100%;

[0060] Slowly digestible starch SDS (%) = (G) 120 -G 20 ) × 0.9 ÷ s × 100%;

[0061] Resistant starch RS (%) = (1 - RDS - SDS) × 100%;

[0062] Glucose content (mg / mL) = ((A) 测定 -A 空白 ) / (A 标准 -A 空白 ))×D;

[0063] Where A is the absorbance value; D is the dilution factor, which is 10 in this experiment;

[0064] Starch digestibility (%) = (Glucose content released × 0.9 / s) × 100%; Glucose content released = G X -G0; where G0 is the free glucose content before enzymatic hydrolysis, in mg; G X σ represents the glucose content in the system after enzymatic hydrolysis for X min, in mg / mL; s represents the total starch content in the sample, in mg / mL; and 0.9 represents the ratio of the relative molecular masses of starch to glucose.

[0065] 4. Emulsifying properties

[0066] Methods: The test particles were prepared into a 2% (w / w) solution. Coconut oil was then added to the completely dissolved solution at an oil-to-water volume ratio of 1:4, and premixed for 5 min using a digital display booster mixer. After the reaction, a high-speed shear emulsifier was used to shear emulsify the emulsion at 10000 r / min for 3 min, repeated three times with a 1 min interval between each shear emulsification. The pre-emulsified emulsion was then homogenized using a dynamic high-pressure microfluidic jet at 150 MPa to obtain a Pickering emulsion, and its stability was then investigated.

[0067] 5. Composite rate

[0068] Methods: Samples processed by a dynamic high-pressure microfluidic homogenizer were centrifuged at 10,000 rpm for 20 min. The supernatant was collected, and the absorbance was immediately measured at 370 nm using a ELISA reader (SpectraMax M2). The absorbance was then substituted into a standard curve to calculate the concentration of free myricetin in the supernatant. The standard curve prepared using anhydrous ethanol-myricetin system (0, 10, 20, 30, 40, 50 μg / mL) was y = 0.0394x + 0.0413, R0. 2=0.9971. The compounding rate EE of myricetin is calculated using the following formula:

[0069] EE (%) = Free myricetin content ÷ Total myricetin added × 100%.

[0070] 6. Complexation rate

[0071] Method: Add 0.4 mL of sample to 9.6 mL of ultrapure water, add 40 μL of standard iodine solution (0.1 mol / L), shake thoroughly, and measure the absorbance at 620 nm. The complexation rate CI of myricetin is calculated using the following formula:

[0072] CI (%) = (A0-A1)÷A0×100%;

[0073] Where A0 is the absorbance of the pregelatinized starch and A1 is the absorbance of the complex.

[0074] 7. Antibacterial properties

[0075] Methods: Activated Staphylococcus aureus suspension, Escherichia coli suspension, and Pseudomonas aeruginosa suspension were evenly spread on the surface of LB agar medium. Holes were then punched using a hole puncher, and Pickering emulsion was added. After incubation in an incubator, the diameter of the inhibition zone was measured.

[0076] Example 1

[0077] Preparation of tapioca starch micron (MTS):

[0078] Take 500g of natural cassava starch (TS) and pour it into an ultrafine pulverizer. Start the cooling device to control the temperature at 0℃ and perform ultrafine pulverization on the sample for 60 minutes to obtain cassava starch powder.

[0079] Example 2

[0080] Preparation of cassava starch nanoparticles:

[0081] 5g of the cassava starch micropowder prepared in Example 1 was added to 100mL of ultrapure water to prepare a 5% starch suspension. The suspension was then processed once each in a high-pressure microfluidic homogenizer (NanoGenizer 30K) at pressures of 50MPa, 100MPa, 150MPa, and 200MPa. After cooling to room temperature, the suspension was frozen at -80℃ overnight and then freeze-dried at -40℃ for 48h using a freeze dryer (FDU-1100, Japan) to obtain cassava starch nanoparticles.

[0082] Example 3

[0083] Preparation of cassava starch-myricetin composite nanoparticles:

[0084] 5g of the cassava starch micropowder prepared in Example 1 was added to 100mL of ultrapure water to prepare a 5% starch suspension. 2% (by weight) of myricetin (MY) from the cassava starch micropowder was dissolved in 10mL of ethanol and added dropwise to the starch suspension. The mixture was stirred at 500 rpm in the dark for 8 min. Subsequently, the mixture was treated once each at pressures of 0 MPa (no homogenization), 50 MPa, 100 MPa, 150 MPa, and 200 MPa in a high-pressure microfluidic homogenizer (NanoGenizer 30K). After cooling to room temperature, the suspension was frozen at -80°C overnight and then freeze-dried at -40°C for 48 h using a freeze dryer (FDU-1100, Japan) to obtain cassava starch-myricetin composite nanoparticles.

[0085] SEM images of the TS used in Example 1, the MTS obtained, and the cassava starch nanoparticles obtained under various homogenization pressures in Example 2 are shown below. Figure 1 .

[0086] The particle size determination results of TS used in Example 1 are shown in the figure. Figure 2 The particle size determination results of the MTS prepared in Example 1 are shown in the figure. Figure 3 The particle size determination results of the nanoparticles prepared under various homogeneous pressures in Examples 2(a) and 3(b) are shown in the figure. Figure 4 .

[0087] SEM images of the TS and MTS used in Example 1, the MY used in Example 3, and the cassava starch-myricetin composite nanoparticles prepared under various homogenization pressures in Example 3 are shown below. Figure 5 .

[0088] Figures 1-5 The results showed that the particle size of the cassava starch-myricetin composite nanoparticles was negatively correlated with the pressure value of high-pressure microfluidic homogenization, gradually decreasing with increasing pressure, reaching a minimum value (approximately 65 nm) at 200 MPa. After high-pressure microfluidic homogenization, the composite particles all reached the nanoscale, with PDI values ​​all less than 0.3. The potential values ​​of the composite particles ranged from -7.03 mV to -11 mV, falling between the MTS and MY values. The absolute value of the composite particles gradually increased with increasing pressure, indirectly reflecting that high-pressure microfluidic homogenization facilitates the reaction between cassava starch and myricetin, improving the encapsulation efficiency of the composite particles.

[0089] TS particles have a smooth surface and dense structure, mainly exhibiting a regular circular or near-circular structure, with a particle size of approximately 10 μm. MTS particles have a rough surface and loose structure, exhibiting a plate-like, gelatinized, agglomerated structure, with a particle size of approximately 46 μm. Figure 3The particle size of the composite particles is slightly larger than that of the TS, mainly because the thermal and mechanical energy causes the TS to gelatinize and expand during the ultrafine grinding pretreatment. MY mainly exhibits a rod-like structure. After physically mixing MTS and MY, it can be observed that MTS mainly adheres to the surface of MY, and the composite is aggregated. After high-pressure microfluidic homogenization, the composite particles are spherical and uniformly dispersed within the field of view. With increasing pressure, the particle size of the composite particles gradually decreases, and the amount of MY encapsulated increases, which is consistent with the results for particle size and composite rate.

[0090] The RDS, SDS, and RS test results for the digestibility of TS used in Example 1, the MTS prepared therefrom, and the cassava starch nanoparticles prepared under various homogenization pressures in Example 2 are shown below. Figure 6 .

[0091] The RDS, SDS, and RS test results for the digestibility of the TS used in Example 1, the MTS prepared therefrom, and the cassava starch-myricetin composite nanoparticles prepared under various homogenization pressures in Example 3 are shown below. Figure 7 .

[0092] The starch digestibility test results for the TS used in Example 1, the MTS prepared therefrom, and the cassava starch nanoparticles prepared under various homogenization pressures in Example 2 are shown below. Figure 8 .

[0093] The starch digestibility test results for the TS used in Example 1, the MTS prepared therefrom, and the cassava starch-myricetin composite nanoparticles prepared under various homogenization pressures in Example 3 are shown below. Figure 9 .

[0094] Figures 6-9 The results showed that with increasing mechanical processing, the digestibility and rapidly digestible starch content of pure cassava starch gradually increased, while the resistant starch content gradually decreased. However, when MTS and MY were simply mixed, the digestibility and rapidly digestible starch content decreased compared to MTS. With increasing pressure, the rapidly digestible starch content of the composite granules gradually increased, but the resistant starch content reached its maximum at 150 MPa, and then decreased again at 200 MPa.

[0095] The emulsification properties of the TS used in Example 1, the MTS prepared therefrom, and the cassava starch nanoparticles prepared under various homogenization pressures in Example 2 are shown in the test results. Figure 10 .

[0096] Example 3: The emulsification properties of the cassava starch-myricetin composite nanoparticles prepared under various homogenization pressures are shown in the figure. Figure 11 .

[0097] Figure 10 and Figure 11The results showed that TS and MTS had no emulsifying effect. Compared with TS and MTS, the emulsifying effect of the cassava starch-myricetin composite nanoparticles was improved, but stratification of varying degrees occurred on the second day. Throughout the storage period, the stratification gradually intensified with the increase of days. Under the same pressure treatment conditions, the emulsifying effect of the composite particles was significantly improved compared with pure cassava starch, with the composite nanoparticles homogenized at 150 MPa showing relatively superior performance. The composite nanoparticles will be used to further prepare Pickering emulsions.

[0098] The myricetin composite rate test results of the cassava starch-myricetin composite nanoparticles prepared under various homogenization pressures in Example 3 are shown below. Figure 12 .

[0099] Figure 12 The results show that as the homogenization pressure level increases from 0 MPa to 200 MPa, the composite rate (encapsulation rate) increases from the initial 93% to 97%.

[0100] The myricetin complexation rate of the cassava starch-myricetin composite nanoparticles prepared under various homogenization pressures in Example 3 is shown in the figure below. Figure 13 .

[0101] Figure 13 The results showed that the myricetin complexation rate of the cassava starch-myricetin composite nanoparticles was positively correlated with pressure in the range of 0–150 MPa, but decreased when the pressure reached 200 MPa. This may be because appropriate pressure can improve the binding degree between cassava starch powder and myricetin, while excessive pressure will cause the tightly bound structure to loosen, which is the main reason why the composite rate increases and the complexation rate decreases at 200 MPa.

[0102] Example 4

[0103] Preparation of Pickering emulsion of coconut oil-cinnamon essential oil stabilized by cassava starch-myricetin composite nanoparticles:

[0104] Tapioca starch-myricetin composite nanoparticles were prepared into starch solutions with appropriate mass fractions (0.5%, 1.0%, 1.5%, 2.0%, 2.5%). Then, a composite oil phase (5%, 10%, 15%, 20%, 25% of total volume) of equal mass of coconut oil and cinnamon essential oil was added to the completely dissolved starch solution and premixed for 5 min using a digital display power mixer. After the reaction, a high-speed shear emulsifier was used for shear emulsification at 10000 r / min for 3 min, repeated three times with a 1 min interval between each shear emulsification. The pre-emulsified emulsion was then homogenized at 150 MPa (1–9 times) using a dynamic high-pressure microfluidic homogenizer to obtain Pickering emulsions.

[0105] The composite oil phase ratio for different mass fractions of starch solutions was selected to be 20%, and the dynamic high-pressure microfluidic homogenization was performed 5 times. It was found that the optimal starch solution mass fraction was 1.0%, and this concentration was subsequently used for the next screening condition.

[0106] The starch solution mass fraction selected for different composite oil phase ratios was 1.0%, and the dynamic high-pressure microfluidic homogenization was performed 5 times. It was found that the optimal composite oil phase ratio was 15%, and this ratio will be used for the next screening condition.

[0107] The starch solution mass fraction selected for different dynamic high-pressure microjet homogenization times was 1.0%, and the composite oil phase ratio was 15%. It was found that the composite oil phase ratio of 15% was optimal.

[0108] Optical microscope magnified images of Pickering emulsions prepared with starch solutions of different mass fractions, starches with different proportions of composite oil phases, and different dynamic high-pressure microfluidic homogenization times are shown below. Figure 14 See macro chart Figure 15 .

[0109] The particle size (a) and zeta potential (d) of Pickering emulsions prepared with starch solutions of different mass fractions, the particle size (b) and zeta potential (e) of Pickering emulsions prepared with different dynamic high-pressure microfluidic homogenization times, and the particle size (c) and zeta potential (f) of Pickering emulsions prepared with different composite oil phase ratios are shown in [reference needed]. Figure 16 .

[0110] Figures 14-16 The optimal preparation conditions for Pickering emulsion are: starch solution mass fraction 1.0%, composite oil phase 15%, and dynamic high-pressure microfluidic homogenization 5 times.

[0111] Magnified optical microscope images of the Pickering emulsion prepared under optimal conditions and stored in the dark for different times are shown below. Figure 17 .

[0112] from Figure 17 As can be seen, the stability of the composite emulsion remained good throughout the entire storage period.

[0113] Comparative Example 1

[0114] Preparation of cinnamon oil Pickering emulsion stabilized by cassava starch-myricetin composite nanoparticles:

[0115] Prepared under the optimized conditions of Example 4, the difference being that the composite oil phase was replaced with an equal volume of cinnamon essential oil.

[0116] Comparative Example 2

[0117] Preparation of coconut oil Pickering emulsion stabilized by cassava starch-myricetin composite nanoparticles:

[0118] Prepared under the optimized conditions of Example 4, the difference being that the composite oil phase was replaced with an equal volume of coconut oil.

[0119] The antibacterial properties of the Pickering emulsions prepared under the optimal preparation conditions of Example 4 and those prepared under Comparative Examples 1 and 2 are shown in the antibacterial culture results. Figure 18 The size of the inhibition zone is shown in Table 1.

[0120] Table 1

[0121]

[0122] As can be seen from the data in Table 1, the antibacterial effect of the composite oil-phase Pickering emulsion is comparable to that of the cinnamon essential oil-phase Pickering emulsion, exhibiting significant antibacterial activity, regardless of whether it is pathogenic or putrefactive bacteria. The coconut oil-phase Pickering emulsion did not show a significant antibacterial effect, indicating that the antibacterial function of the composite oil-phase Pickering emulsion is primarily attributable to the cinnamon essential oil.

[0123] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for the preparation of starch-myricetin complex nanoparticle stabilized Pickering emulsions, characterized in that, The method comprises the following steps: The starch is crushed to obtain starch powder, and the starch powder is made into a suspension, then dropped into an alcohol solution containing myricetin, and reacted in the dark, followed by dynamic high-pressure microfluidization homogenization, and then freeze-drying to obtain starch-myricetin composite nanoparticles. The starch-myricetin composite nanoparticles are made into a suspension, emulsified with a composite oil phase mixed with coconut oil and cinnamon essential oil, and then subjected to dynamic high-pressure microfluidization homogenization to obtain the stable Pickering emulsion of the starch-myricetin composite nanoparticles.

2. The process for the preparation of starch-myricetin complex nanoparticle stabilized Pickering emulsions according to claim 1, characterized in that, The particle size of the starch powder is 20-50 μm.

3. The method for preparing starch-myricetin complex nanoparticle stabilized Pickering emulsion according to claim 1, characterized in that, The amount of myricetin used is 2% of the mass of the starch powder used; and / or the stirring speed of the light-avoiding reaction is 500 r / min, and the time is 8 min.

4. The process for the preparation of starch-myricetin complex nanoparticle stabilized Pickering emulsion according to claim 1, characterized in that, In the preparation of the starch-myricetin composite nanoparticles, the pressure of the dynamic high-pressure microfluidization homogenization is 150 MPa, and the number of times is 1.

5. The method for preparing starch-myricetin complex nanoparticle stabilized Pickering emulsion according to claim 1, characterized in that, The mass fraction of the starch-myricetin composite nanoparticle suspension is 1.0%.

6. The method for preparing starch-myricetin complex nanoparticle stabilized Pickering emulsion according to claim 1, characterized in that, The mass ratio of the coconut oil and the cinnamon essential oil is 1:

1.

7. The method for preparing starch-myricetin complex nanoparticle stabilized Pickering emulsion according to claim 1, characterized in that, The volume ratio of the starch-myricetin composite nanoparticle suspension to the composite oil phase is 85:

15.

8. The method for preparing starch-myricetin complex nanoparticle stabilized Pickering emulsion according to claim 1, characterized in that, The shear rate of the emulsification is 10,000 r / min, the shear time is 3 min, and the number of times of shear emulsification is 3; and / or in the homogenization of the emulsified product, the pressure of the dynamic high-pressure microfluidization homogenization is 150 MPa, and the number of times is 5.

9. A stable Pickering emulsion of starch-myricetin composite nanoparticles prepared by the method according to any one of claims 1-8.

10. The use of the stable Pickering emulsion of starch-myricetin composite nanoparticles according to claim 9 in food preservation.

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