A Pickering emulsion with high oxidation resistance and strong thermal stability and its preparation method and application

Abstract

The invention discloses a Pickering emulsion with high antioxidant and strong thermal stability, a preparation method and application thereof, and belongs to the technical field of Pickering emulsion. The invention uses zein and rosemary essential oil as raw materials, and prepares a Pickering emulsion with high antioxidant and strong thermal stability through high-speed homogenization and ultrasonic treatment. The Pickering emulsion prepared by the invention has the advantages of small particle size, high centrifugal stability, good temperature stability, high encapsulation rate and strong antioxidant capacity, and can be widely used in the fields of food, cosmetics, etc.

Description

Technical Field

[0001] The invention belongs to the technical field of Pickering emulsions, and more specifically relates to a Pickering emulsion with high oxidation resistance and strong thermal stability, and a preparation method and application thereof. Background Art

[0002] Traditional plastics have made significant contributions to the development of the food packaging industry due to their functions in sealing, protecting and distributing food. Most of the traditional plastics are non-biodegradable, disposable petroleum-based polymers, which bring certain harm to the environment and human health. In order to overcome the threats associated with petroleum-based plastic packaging materials, research and development of sustainable resources are being actively carried out to develop biodegradable and renewable packaging materials with eco-friendly properties. Essential oils, as natural bioactive compounds extracted from plants, have received extensive attention in food active packaging films due to their safe and effective blood-activating functions. Rosemary essential oil contains active ingredients such as α-pinene, β-pinene, camphor, caryophyllene, etc., and has excellent antioxidant and antibacterial activities. However, since essential oils are volatile, they are greatly affected by environmental factors and have poor biocompatibility with packaging films. Pickering emulsions, as a delivery system for bioactive compounds, have the protective and controlled release effects of bioactive compounds. Zein is a natural plant protein. As an encapsulation material for Pickering emulsions, it can achieve the effects of avoiding the use of organic surfactants, anti-evaporation, slow release, and reducing odor. Summary of the invention

[0003] In view of the above problems existing in the prior art, the technical problem to be solved by the present invention is to provide a method for preparing a Pickering emulsion with high oxidation resistance and strong thermal stability, which has the advantages of simple preparation process and easy industrial production. Another technical problem to be solved by the present invention is to provide a Pickering emulsion with high oxidation resistance and strong thermal stability prepared by the above method, and the prepared Pickering emulsion with high oxidation resistance and strong thermal stability has a small particle size, high centrifugal stability, good temperature stability, high encapsulation rate and strong antioxidant ability. Another technical problem to be solved by the present invention is to provide the application of the above Pickering emulsion with high oxidation resistance and strong thermal stability in encapsulation materials.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0005] The invention discloses a method for preparing a Pickering emulsion with high antioxidant and strong thermal stability. The method uses zein and rosemary essential oil as raw materials and carries out high-speed homogenization and ultrasonic treatment to prepare the Pickering emulsion with high antioxidant and strong thermal stability.

[0006] Preferably, the speed of the high-speed homogenization is 9000-21000 rpm, and the time is 2-10 min; the power of the ultrasonic treatment is 240-480 W, and the time is 2-10 min.

[0007] Preferably, the speed of the high-speed homogenization is 12600 rpm, and the time is 4 min; the power of the ultrasonic treatment is 300 w, and the time is 3 min.

[0008] The method for preparing the Pickering emulsion with high oxidation resistance and strong thermal stability comprises the following steps:

[0009] 1) dissolving zein in an acetic acid solution to obtain a zein stock solution;

[0010] 2) dropping the zein stock solution obtained in step 1) into distilled water, and homogenizing at high speed to obtain a zein nanoparticle solution;

[0011] 3) adding rosemary essential oil dropwise into the zein nanoparticle solution obtained in step 2), homogenizing at 9000-21000 rpm for 2-10 min, and then treating with ultrasonic power at 240-480 W for 2-10 min to prepare a Pickering emulsion.

[0012] Preferably, in step 2), the speed of high-speed homogenization is 12000 rpm and the homogenization time is 2 min.

[0013] Preferably, in step 2), the concentration of zein nanoparticles is 1-3% (g / mL).

[0014] Preferably, in step 3), the ratio of rosemary essential oil to oil in the zein nanoparticle solution is 20-60%.

[0015] Preferably, in step 3), the speed of high-speed homogenization is 9000-15000 rpm, and the time is 4 min; the power of ultrasonic treatment is 300 W, and the time is 2-6 min.

[0016] The method for preparing the Pickering emulsion with high oxidation resistance and strong thermal stability can prepare the Pickering emulsion with high oxidation resistance and strong thermal stability.

[0017] The Pickering emulsion with high oxidation resistance and strong thermal stability is used in encapsulation materials.

[0018] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0019] 1) The Pickering emulsion prepared by the present invention has the advantages of small particle size, high centrifugal stability and good temperature stability, and can be widely used in the fields of food, cosmetics, etc.;

[0020] 2) Compared with the Pickering emulsion prepared by the existing common process of high-speed homogenization, the Pickering emulsion prepared by the present invention has the advantages of high encapsulation rate and strong antioxidant capacity, and has good functional activity. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The appearance of the prepared Pickering emulsion; Figures AF are the appearance of the emulsion under different zein nanoparticle concentrations, oil ratios, homogenization time, homogenization speed, ultrasonic power, and ultrasonic time conditions, respectively;

[0022] Figure 2 Figure 1 is a particle size-PDI-ζ potential diagram of Pickering emulsions with different zein nanoparticle concentrations; Figure A is a particle size and PDI diagram, and Figure B is a ζ potential diagram;

[0023] Figure 3 The particle size-PDI-zeta potential diagrams of Pickering emulsions with different oil ratios; Figure A is the particle size-PDI diagram, and Figure B is the zeta potential diagram;

[0024] Figure 4 Figure 1 is a particle size-PDI-ζ potential diagram of Pickering emulsions at different homogenization times; Figure A is a particle size-PDI diagram, and Figure B is a ζ potential diagram;

[0025] Figure 5 Figure 1 is a particle size-PDI-ζ potential diagram of Pickering emulsions at different homogenization speeds; Figure A is a particle size-PDI diagram, and Figure B is a ζ potential diagram;

[0026] Figure 6 Figure 1 is a particle size-PDI-ζ potential diagram of Pickering emulsions with different ultrasonic powers; Figure A is a particle size-PDI diagram, and Figure B is a ζ potential diagram;

[0027] Figure 7 Figure 1 is a particle size-PDI-ζ potential diagram of Pickering emulsions at different ultrasonic times; Figure A is a particle size-PDI diagram, and Figure B is a ζ potential diagram;

[0028] Figure 8The interactive contour maps and 3D maps of protein concentration-homogenization speed-ultrasonic time are shown in Figure 1; Figure a1 is an interactive contour map of protein concentration-homogenization speed, Figure a2 is an interactive 3D map of protein concentration-homogenization speed, Figure b1 is an interactive contour map of protein concentration-ultrasonic time, Figure b2 is an interactive 3D map of protein concentration-homogenization speed, Figure c1 is an interactive contour map of homogenization speed-ultrasonic time, and Figure c2 is an interactive 3D map of homogenization speed-ultrasonic time;

[0029] Fig. 9 The appearance-particle size, PDI-ζ potential diagram of 1.7% (w / v) zein nanoparticles;

[0030] Fig.10 This is the appearance-particle size-PDI-zeta potential diagram of the preferred Pickering emulsion (prepared in Example 39);

[0031] Fig.11 The appearance-particle size-PDI-zeta potential diagram of the preferred Pickering emulsion (prepared in Example 39) before and after centrifugation;

[0032] Fig.12 The appearance of the preferred Pickering emulsion (prepared in Example 39) at room temperature for 0 to 16 days;

[0033] Fig.13 The appearance-particle size-zeta potential diagram of the preferred Pickering emulsion (prepared in Example 39) after being placed at 20-80°C for 30 minutes; wherein, Figure A is a particle size diagram, and Figure B is a zeta potential diagram;

[0034] Fig.14 The appearance of the preferred Pickering emulsion (prepared in Example 39) after being placed at 20-80°C for 30 minutes and then at room temperature for 0-12 days;

[0035] Fig.15 is a graph showing the essential oil encapsulation efficiency of a preferred Pickering emulsion (prepared in Example 39);

[0036] Fig.16 The antioxidant activity of the preferred Pickering emulsion (prepared in Example 39) is shown in FIG. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described below in conjunction with specific embodiments. In the following examples, unless otherwise specified, the technical means used are conventional means well known to those skilled in the art. If specific conditions are not specified in the examples, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0038] The rosemary essential oil used in the following examples was purchased from Maclean, and the zein was purchased from Sigma-Aldrich.

[0039] The performance testing method adopted by the present invention is as follows:

[0040] 1. Determination of zeta potential, PDI and particle size: The particle size, PDI and zeta potential of Pickering emulsion were determined by Zeta potential meter. Before measurement, the sample was diluted 1:100 with distilled water to eliminate the multiple scattering effect.

[0041] 2. Response surface Box-Behnken test: Based on the single factor experiment, a response surface experiment with three factors and three levels of protein concentration, homogenization speed and ultrasonic time was designed, and a model was established. The experimental results were predicted and verified based on the regression model.

[0042] Example 1

[0043] A method for preparing a Pickering emulsion with high oxidation resistance and strong thermal stability comprises the following steps:

[0044] 1) dissolving zein in 90% acetic acid solution to obtain a zein stock solution;

[0045] 2) dropping the zein stock solution obtained in step 1) into distilled water, and homogenizing at 12000 rpm for 2 min to prepare 1-3% (g / mL, the solvent is the volume of distilled water, the same below) zein nanoparticles;

[0046] 3) adding 1-3% (g / mL) zein nanoparticle solution to 20-60% rosemary essential oil by volume, homogenizing at 9000-21000 rpm for 2-10 min, and then treating at 240-480 w ultrasonic power for 2-10 min to prepare zein-based rosemary essential oil Pickering emulsion.

[0047] Example 2

[0048] A method for preparing a Pickering emulsion with high oxidation resistance and strong thermal stability comprises the following steps:

[0049] 1) dissolving zein in 90% acetic acid solution to obtain a zein stock solution;

[0050] 2) dropping the zein stock solution obtained in step 1) into distilled water, and homogenizing at 12000 rpm for 2 min to prepare a 2% (g / mL) zein nanoparticle solution;

[0051] 3) Rosemary essential oil was dripped into the 2% (g / mL) zein nanoparticles prepared in step 2) to make the oil phase ratio 50%, and the mixture was homogenized at 12000 rpm for 4 min, and then treated at 300 W ultrasonic power for 4 min to prepare a zein-based rosemary essential oil Pickering emulsion.

[0052] Example 3

[0053] When preparing the Pickering emulsion, the concentration of the zein nanoparticle solution was 1% (g / mL), and the remaining preparation methods and parameters were the same as those in Example 2.

[0054] Example 4

[0055] When preparing the Pickering emulsion, the concentration of the zein nanoparticle solution was 1.5% (g / mL), and the remaining preparation methods and parameters were the same as those in Example 2.

[0056] Example 5

[0057] When preparing the Pickering emulsion, the concentration of the zein nanoparticle solution was 2.5% (g / mL), and the remaining preparation methods and parameters were the same as those in Example 2.

[0058] Example 6

[0059] When preparing the Pickering emulsion, the concentration of the zein nanoparticle solution was 3% (g / mL), and the remaining preparation methods and parameters were the same as those in Example 2.

[0060] Example 7

[0061] When preparing the Pickering emulsion, the ratio of rosemary essential oil to the oil of the zein nanoparticle solution was 20%, and the remaining preparation methods and parameters were the same as those in Example 2.

[0062] Example 8

[0063] When preparing the Pickering emulsion, the ratio of rosemary essential oil to the oil of the zein nanoparticle solution was 30%, and the remaining preparation methods and parameters were the same as those in Example 2.

[0064] Example 9

[0065] When preparing the Pickering emulsion, the ratio of rosemary essential oil to the oil of the zein nanoparticle solution was 40%. The remaining preparation methods and parameters were the same as those in Example 2.

[0066] Example 10

[0067] When preparing the Pickering emulsion, the ratio of rosemary essential oil to the oil of the zein nanoparticle solution was 60%, and the remaining preparation methods and parameters were the same as those in Example 2.

[0068] Embodiment 11

[0069] When preparing the Pickering emulsion, the high-speed homogenization time of the rosemary essential oil and the zein nanoparticle solution was 2 min, and the other preparation methods and parameters were the same as those in Example 2.

[0070] Example 12

[0071] When preparing the Pickering emulsion, the high-speed homogenization time of the rosemary essential oil and the zein nanoparticle solution was 6 minutes, and the other preparation methods and parameters were the same as those in Example 2.

[0072] Example 13

[0073] When preparing the Pickering emulsion, the high-speed homogenization time of the rosemary essential oil and the zein nanoparticle solution was 8 minutes, and the other preparation methods and parameters were the same as those in Example 2.

[0074] Embodiment 14

[0075] When preparing the Pickering emulsion, the high-speed homogenization time of the rosemary essential oil and the zein nanoparticle solution was 10 min, and the other preparation methods and parameters were the same as those in Example 2.

[0076] Embodiment 15

[0077] When preparing the Pickering emulsion, the rotation speed of the high-speed homogenization of rosemary essential oil and zein nanoparticle solution was 9000 rpm, and the remaining preparation methods and parameters were the same as those in Example 2.

[0078] Example 16

[0079] When preparing the Pickering emulsion, the rotation speed of the high-speed homogenization of rosemary essential oil and zein nanoparticle solution was 15000 rpm, and the other preparation methods and parameters were the same as those in Example 2.

[0080] Embodiment 17

[0081] When preparing the Pickering emulsion, the rotation speed of the high-speed homogenization of rosemary essential oil and zein nanoparticle solution was 18000 rpm, and the remaining preparation methods and parameters were the same as those in Example 2.

[0082] Embodiment 18

[0083] When preparing the Pickering emulsion, the rotation speed of the high-speed homogenization of rosemary essential oil and zein nanoparticle solution was 21000 rpm, and the other preparation methods and parameters were the same as those in Example 2.

[0084] Embodiment 19

[0085] When preparing the Pickering emulsion, the ultrasonic power of the rosemary essential oil and zein nanoparticle solution was 240 W, and the remaining preparation methods and parameters were the same as those in Example 2.

[0086] Embodiment 20

[0087] When preparing the Pickering emulsion, the ultrasonic power of the rosemary essential oil and zein nanoparticle solution was 360 w, and the remaining preparation methods and parameters were the same as those in Example 2.

[0088] Embodiment 21

[0089] When preparing the Pickering emulsion, the ultrasonic power of the rosemary essential oil and zein nanoparticle solution was 420 w, and the remaining preparation methods and parameters were the same as those in Example 2.

[0090] Embodiment 22

[0091] When preparing the Pickering emulsion, the ultrasonic power of the rosemary essential oil and zein nanoparticle solution was 480 w, and the remaining preparation methods and parameters were the same as those in Example 2.

[0092] Embodiment 23

[0093] When preparing the Pickering emulsion, the ultrasonic time of the rosemary essential oil and the zein nanoparticle solution was 2 min, and the other preparation methods and parameters were the same as those in Example 2.

[0094] Embodiment 24

[0095] When preparing the Pickering emulsion, the ultrasonic time of the rosemary essential oil and the zein nanoparticle solution was 6 minutes, and the other preparation methods and parameters were the same as those in Example 2.

[0096] Embodiment 25

[0097] When preparing the Pickering emulsion, the ultrasonic time of the rosemary essential oil and the zein nanoparticle solution was 8 min, and the other preparation methods and parameters were the same as those in Example 2.

[0098] Embodiment 26

[0099] When preparing the Pickering emulsion, the ultrasonic time of the rosemary essential oil and the zein nanoparticle solution was 10 min, and the other preparation methods and parameters were the same as those in Example 2.

[0100] Embodiment 27

[0101] When preparing the Pickering emulsion, the concentration of the zein nanoparticle solution was 1.5% (g / mL), the speed of high-speed homogenization of rosemary essential oil and zein nanoparticle solution was 9000 rpm, the ultrasonic time was 4 min, and the remaining preparation methods and parameters were the same as those in Example 2.

[0102] Embodiment 28

[0103] When preparing the Pickering emulsion, the concentration of the zein nanoparticle solution was 2.5% (g / mL), the speed of high-speed homogenization of rosemary essential oil and zein nanoparticle solution was 9000 rpm, the ultrasonic time was 4 min, and the remaining preparation methods and parameters were the same as those in Example 2.

[0104] Embodiment 29

[0105] When preparing the Pickering emulsion, the concentration of the zein nanoparticle solution was 1.5% (g / mL), the speed of high-speed homogenization of rosemary essential oil and zein nanoparticle solution was 15000 rpm, the ultrasonic time was 4 min, and the remaining preparation methods and parameters were the same as those in Example 2.

[0106] Embodiment 30

[0107] When preparing the Pickering emulsion, the concentration of the zein nanoparticle solution was 2.5% (g / mL), the speed of high-speed homogenization of rosemary essential oil and zein nanoparticle solution was 15000 rpm, the ultrasonic time was 4 min, and the remaining preparation methods and parameters were the same as those in Example 2.

[0108] Embodiment 31

[0109] When preparing the Pickering emulsion, the concentration of the zein nanoparticle solution was 1.5% (g / mL), the speed of high-speed homogenization of rosemary essential oil and zein nanoparticle solution was 12000 rpm, the ultrasonic time was 4 min, and the remaining preparation methods and parameters were the same as those in Example 2.

[0110] Embodiment 32

[0111] When preparing the Pickering emulsion, the concentration of the zein nanoparticle solution was 2.5% (g / mL), the speed of high-speed homogenization of rosemary essential oil and zein nanoparticle solution was 12000 rpm, the ultrasonic time was 4 min, and the remaining preparation methods and parameters were the same as those in Example 2.

[0112] Embodiment 33

[0113] When preparing the Pickering emulsion, the concentration of the zein nanoparticle solution was 1.5% (g / mL), the speed of high-speed homogenization of rosemary essential oil and zein nanoparticle solution was 12000 rpm, the ultrasonic time was 6 min, and the remaining preparation methods and parameters were the same as those in Example 2.

[0114] Embodiment 34

[0115] When preparing the Pickering emulsion, the concentration of the zein nanoparticle solution was 2.5% (g / mL), the speed of high-speed homogenization of rosemary essential oil and zein nanoparticle solution was 12000 rpm, the ultrasonic time was 6 min, and the remaining preparation methods and parameters were the same as those in Example 2.

[0116] Embodiment 35

[0117] When preparing the Pickering emulsion, the speed of high-speed homogenization of rosemary essential oil and zein nanoparticle solution was 9000 rpm, the ultrasonic time was 2 min, and the other preparation methods and parameters were the same as those in Example 2.

[0118] Embodiment 36

[0119] When preparing the Pickering emulsion, the speed of high-speed homogenization of rosemary essential oil and zein nanoparticle solution was 15000 rpm, the ultrasonic time was 2 min, and the other preparation methods and parameters were the same as those in Example 2.

[0120] Embodiment 37

[0121] When preparing the Pickering emulsion, the speed of high-speed homogenization of rosemary essential oil and zein nanoparticle solution was 9000 rpm, the ultrasonic time was 6 min, and the other preparation methods and parameters were the same as those in Example 2.

[0122] Embodiment 38

[0123] When preparing the Pickering emulsion, the speed of high-speed homogenization of rosemary essential oil and zein nanoparticle solution was 15000 rpm, the ultrasonic time was 6 min, and the other preparation methods and parameters were the same as those in Example 2.

[0124] Embodiment 39

[0125] When preparing the Pickering emulsion, the concentration of the zein nanoparticle solution was 1.7% (g / mL), the speed of high-speed homogenization of rosemary essential oil and zein nanoparticle solution was 12600 rpm, the ultrasonic time was 3 min, and the remaining preparation methods and parameters were the same as those in Example 2.

[0126] Embodiment 40

[0127] The properties of the zein-based rosemary essential oil Pickering emulsions prepared in Examples 2 to 39 were measured.

[0128] 1. Determination of emulsion particle size, PDI and zeta potential

[0129] The particle size and PDI of the Pickering emulsion were measured by DLS and the zeta potential was measured by PALS using a zeta potential meter. The particle size, PDI and zeta potential of the Pickering emulsions of Experimental Examples 2 to 26 are shown in Table 1. Figures 2 to 7 As shown. Figure 1 It can be seen that the Pickering emulsion with an oil phase of 60% has a phase transition.

[0130] Depend on Figure 2 It can be seen that the particle size of the Pickering emulsions prepared in Examples 2 to 6 first decreases and then increases, the PDI is less than 0.4, the zeta potential is greater than 30 mV, and more preferably, the concentration of zein nanoparticles is 1.5 to 2.5% (g / mL).

[0131] Depend on Figure 3 It can be seen that the particle size of the Pickering emulsions prepared in Examples 2 and 7 to 10 is the minimum when the oil phase ratio is 50%, the PDI is less than 0.4, and the zeta potential is greater than 30 mV. More preferably, the oil phase ratio is 50%.

[0132] Depend on Figure 4 It can be seen that the particle size of the Pickering emulsions prepared in Examples 2 and 11 to 14 gradually increases, the PDI is less than 0.4, the zeta potential increases first and then decreases, and more preferably, the homogenization time is 4 minutes.

[0133] Depend on Figure 5 It can be seen that the particle size of the Pickering emulsions prepared in Examples 2 and 15 to 18 first decreases and then increases, the PDI is less than 0.4, the zeta potential is greater than 30 mV, and more preferably, the homogenization speed is 9000 to 15000 rpm.

[0134] Depend on Figure 6It can be seen that the particle size of the Pickering emulsions prepared in Examples 2 and 19 to 22 first decreases and then increases, the PDI is less than 0.4, the zeta potential is greater than 30 mV, and more preferably, the ultrasonic power is 300 w.

[0135] Depend on Figure 7 It can be seen that the particle size of the Pickering emulsions prepared in Examples 2 and 23 to 26 first decreases and then increases, the PDI is less than 0.4, the zeta potential is greater than 30 mV, and more preferably, the ultrasonic time is 2 to 6 min.

[0136] Examples 27 to 38 were subjected to response surface Box-Behnken experiments to establish a regression model to predict and verify the experimental results. Figure 8 As shown in Figure , the optimal zein nanoparticle concentration and Pickering emulsion were screened out, such as Figures 9-10 As shown, the optimal 1.7% (w / v) zein nanoparticles have a particle size of 203.0±7.253 nm, a PDI of 0.281±0.012, and a zeta potential of 54.3±2.833 mV. The optimal Pickering emulsion (Example 39) has a particle size of 938.8±33.41 nm, a PDI of 0.074±0.06, and a zeta potential of 49.03±1.763 mV.

[0137] (2) Centrifugal stability measurement

[0138] The optimal Pickering emulsion prepared in Example 39 was centrifuged at 6000 rpm for 15 min and then shaken to measure the particle size, PDI and zeta potential of the emulsion. Fig.11 As shown. Fig.11 It can be seen that after centrifugation and shaking, the Pickering emulsion particle size is 994.9±57.28nm, the PDI is 0.200±0.065, and the ζ potential is 47.28±3.536mV; the emulsion particle size and ζ potential change little before and after centrifugation, and the PDI is less than 0.4, indicating that the prepared Pickering emulsion has good centrifugal stability.

[0139] (3) Storage stability

[0140] The optimal Pickering emulsion prepared in Example 39 was placed at room temperature for 0 to 16 days. Fig.12 shown.

[0141] Depend on Fig.12 It can be seen that after 16 days of storage, the emulsion still has no obvious stratification, which shows that the Pickering emulsion has good storage stability.

[0142] (4) Temperature stability

[0143] The optimal Pickering emulsion prepared in Example 39 was placed at 20-80°C for 30 minutes, cooled to room temperature, and the particle size and zeta potential of the emulsion were measured. Fig.13 As shown. Fig.13 It can be seen that after heating, the appearance of the Pickering emulsion has no obvious change. After being placed at 80°C, the particle size and ζ potential of the emulsion increase significantly.

[0144] The Pickering emulsion cooled to room temperature was allowed to stand for 12 days. Fig.14 As shown. Fig.14 It can be seen that the Pickering emulsion began to stratify on the 8th day and obvious stratification appeared on the 12th day, indicating that the Pickering emulsion has good temperature stability.

[0145] (5) Pickering emulsion essential oil encapsulation efficiency

[0146] Preparation of rosemary essential oil standard curve: Prepare rosemary essential oil-n-hexane standard solutions with concentrations of 0.01, 0.02, 0.03, 0.04, 0.05, and 0.06 mL / L, respectively, and use n-hexane as a blank control. Measure the absorbance value at a wavelength of 296 nm. Draw a standard curve with rosemary essential oil concentration as the horizontal coordinate (mL / L) and absorbance value as the vertical coordinate. The rosemary essential oil standard curve is measured to be y=4.1019x+0.7387R2=0.9915.

[0147] Encapsulation efficiency determination: 0.5 mL Pickering emulsion was mixed with 4.5 mL normal hexane, centrifuged at 5000 rpm for 10 min, the supernatant was collected, diluted 1000 times, and the absorbance was measured at 296 nm. According to the rosemary essential oil standard curve and the corresponding dilution multiple, the free essential oil content in the emulsion can be measured, encapsulation efficiency (%) = (1-free essential oil content / essential oil addition amount) × 100.

[0148] The essential oil encapsulation efficiency of the Pickering emulsion prepared in Example 39 is as follows: Fig.15 shown.

[0149] Depend on Fig.15 It can be seen that the encapsulation efficiency of the Pickering emulsion treated with homogenization and ultrasound is 93.96%, and the encapsulation efficiency of the Pickering emulsion without homogenization and ultrasound treatment is 82.21%. The encapsulation efficiency of the sample group is significantly higher than that of the control group, indicating that high-speed homogenization combined with ultrasound treatment is an effective auxiliary method for preparing zein-based rosemary essential oil Pickering emulsion.

[0150] (6) Determination of DPPH free radical scavenging rate of Pickering emulsion

[0151] 0.5 mL of the Pickering emulsion prepared in Example 39 was mixed with 0.5 mL of 0.1 mmol / L DPPH ethanol solution, placed in the dark for 30 min, and the absorbance was measured at 517 nm. Anhydrous ethanol was substituted for the DPPH ethanol solution as the blank group, and distilled water was substituted for the Pickering emulsion as the control group.

[0152] Clearance rate = (1-(sample-blank) / control) × 100

[0153] The DPPH radical scavenging rate of the Pickering emulsion prepared in Example 39 is as follows: Fig.16 As shown. Fig.16 It can be seen that the removal rate of Pickering emulsion after homogenization and ultrasonic treatment is 89.50%, and the removal rate of Pickering emulsion without homogenization and ultrasonic treatment is 59.17%; the removal rate of the sample group is significantly higher than that of the control group, indicating that high-speed homogenization combined with ultrasonic treatment significantly improves the DPPH free radical removal rate of Pickering emulsion.

[0154] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. Application of a Pickering emulsion with high oxidation resistance and strong thermal stability in encapsulation materials, wherein the Pickering emulsion with high oxidation resistance and strong thermal stability is prepared by the following steps: 1) dissolving zein in 90% acetic acid solution to prepare zein stock solution; 2) dropping the zein stock solution obtained in step 1) into distilled water, and homogenizing at 12000 rpm for 2 min to obtain a zein nanoparticle solution with a concentration of 1.7% g / mL; 3) Rosemary essential oil was dripped into the zein nanoparticle solution obtained in step 2) to make the oil phase ratio 50%, and the mixture was homogenized at 12600 rpm for 4 min, and then treated at 300 W ultrasonic power for 3 min to prepare a Pickering emulsion.

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