Tea residue protein high internal phase pickering emulsion, and preparation method and application thereof

Abstract

The application provides a tea residue protein high internal phase Pickering emulsion and a preparation method and application thereof, and belongs to the technical field of emulsion preparation. The application discloses a preparation method of a tea residue protein high internal phase Pickering emulsion, which comprises the following steps: mixing tea residue protein and water to obtain a tea residue protein suspension; mixing the tea residue protein suspension and a first vegetable oil, and performing ultrasonic crushing to obtain a primary emulsion; mixing the primary emulsion and a second vegetable oil, and performing shearing homogenization to obtain the tea residue protein high internal phase Pickering emulsion. The mass concentration of the tea residue protein in the tea residue protein high internal phase Pickering emulsion is 5-17.5 g / L, and the volume fraction of the oil phase in the emulsion is 75-88%. The high internal phase Pickering emulsion prepared by the application has high storage stability and thermal stability, has good viscoelasticity, can replace solid fat, hydrogenated oil and the like, and has a wide application prospect in novel food additives and food development.

Description

Technical Field

[0001] This invention belongs to the field of emulsion preparation technology, and specifically relates to a tea residue protein high internal phase Pickering emulsion, its preparation method and application. Background Technology

[0002] High internal phase Pickering emulsions (HIPEs) refer to emulsions with a dispersed phase volume fraction exceeding 74.05%. Their application in the food industry has been a research hotspot in recent years. They exhibit greater stability, a pronounced gel-like structure, and wider applicability than traditional Pickering emulsions. They can be used to prepare gels and porous materials, and can replace trans fatty acids as solid fats in food for the preparation of health foods. They also enhance the stability and antioxidant activity of food emulsions. Because oil droplets have lower flowability than water, HIPEs typically exhibit higher stability than ordinary emulsions, making them more resistant to sedimentation, flocculation, or aggregation. Microstructurally, HIPEs consist of compressed droplets with uneven particle sizes. The oil droplets are polydisperse or deformed into a polyhedral arrangement, while the continuous phase acts as a thin film, separating the dispersed phase and creating an overall liquid-liquid foam structure. If the droplet diameter is highly polydisperse, the smaller droplets fill the voids left by the larger droplets, reducing deformation. The high droplet volume fraction causes these systems to exhibit solid-fluid-like behavior, displaying high viscosity and suppressing instabilities such as precipitation or emulsification. High internal phase emulsions possess excellent long-term stability, making them an ideal functional food dosage form.

[0003] Currently, food-grade solid particles used to stabilize HIPEs typically include chitosan, cellulose, starch, polymer particles, inorganic particles, and soy protein. Among these, plant proteins are widely available, nutritious, and have low production costs, making them a viable alternative to animal proteins and possessing immense development potential and production value.

[0004] Existing technologies describe a one-step emulsification method for preparing HIPEs. For example, Wang Yongquan disclosed in "High internal phase emulsions stabilized solely by soy protein isolate" (Journal of Food Engineering, Vol. 318, 2021) that corn oil containing soy protein isolate dispersion was sheared at 13200 r / min for 1 minute to prepare HIPEs. The appearance of the emulsion after heating did not show significant differences, but phase separation occurred after freeze-thaw treatment. It can be seen that the high internal phase Pickering emulsion prepared by the above one-step emulsification method has the technical problem of poor stability. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a tea residue protein high internal phase Pickering emulsion, its preparation method and application. The high internal phase Pickering emulsion prepared by this invention using tea residue protein has higher stability.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] A method for preparing a tea residue protein high internal phase Pickering emulsion includes the following steps:

[0008] Tea residue protein and water are mixed to obtain a tea residue protein suspension;

[0009] The tea residue protein suspension was mixed with the first vegetable oil and ultrasonically pulverized to obtain the primary emulsion.

[0010] The primary emulsion and the second vegetable oil were mixed and sheared to obtain the tea residue protein high internal phase Pickering emulsion.

[0011] Preferably, the concentration of the tea residue protein suspension is 50–125 g / L; and the pH value of the tea residue protein suspension is 6–8.5.

[0012] Preferably, both the first and second vegetable oils include one or more of camellia oil, corn oil, and soybean oil.

[0013] Preferably, the volume ratio of the tea residue protein suspension to the first vegetable oil is 3:0.75-7.

[0014] Preferably, the ultrasonic pulverizing power is 285-500W, and the ultrasonic pulverizing time is 1-3 minutes.

[0015] Preferably, the volume ratio of the primary emulsion to the second vegetable oil is 1:0.5 to 3.

[0016] Preferably, the shear homogenization time is 1 to 3 minutes, and the shear homogenization rate is 8000 to 15000 r / min.

[0017] This invention provides a tea residue protein high internal phase Pickering emulsion prepared by the aforementioned method, wherein the tea residue protein high internal phase Pickering emulsion comprises: tea residue protein, vegetable oil, and water; the tea residue protein high internal phase Pickering emulsion is an O / W system; the volume fraction of the oil phase in the tea residue protein high internal phase Pickering emulsion is 75-88%; and the vegetable oil is one of the first vegetable oil or the second vegetable oil.

[0018] Preferably, the concentration of tea residue protein in the tea residue protein high internal phase Pickering emulsion is 5–17.5 g / L.

[0019] This invention also provides the application of the tea residue protein high internal phase Pickering emulsion described above in the food or cosmetic fields or in the preparation of pharmaceutical products.

[0020] This invention provides a method for preparing a high internal phase Pickering emulsion of tea residue protein, comprising the following steps: mixing the tea residue protein with water to obtain a tea residue protein suspension; mixing the tea residue protein suspension with a first vegetable oil and ultrasonically pulverizing it to obtain a primary emulsion; mixing the primary emulsion with a second vegetable oil and shearing homogenizing it to obtain the high internal phase Pickering emulsion of tea residue protein.

[0021] Beneficial effects:

[0022] On the one hand, the preparation method provided by this invention first prepares a primary emulsion with a low oil phase volume fraction using high-energy ultrasonic input, and then increases the oil phase volume fraction in the primary emulsion using low-energy shear homogenization. This solves the problem that natural tea residue protein often has poor emulsification properties due to its compact molecular structure, thus improving the emulsification properties and emulsion stability of tea residue protein, thereby preparing a high internal phase Pickering emulsion. The preparation method provided by this invention, through the stepwise addition of vegetable oil combined with ultrasonic pulverization and shear homogenization, yields a high internal phase Pickering emulsion of tea residue protein with high storage and thermal stability, solving the problem of poor emulsion stability in one-step emulsification methods.

[0023] Furthermore, the preparation method provided by this invention enables the tea residue protein in the tea residue protein high internal phase Pickering emulsion to be adsorbed onto the oil-water interface, resulting in a stronger gel network structure of the emulsion, thereby exhibiting good viscoelasticity and improving the stability of the emulsion. It can be used to replace solid fats and hydrogenated oils, and has broad application prospects in the fields of novel food additives or cosmetics, or in the preparation of pharmaceutical products.

[0024] This invention also provides the application of the tea residue protein high internal phase Pickering emulsion prepared by the above-mentioned technical solution in the food or cosmetic fields, or in the preparation of pharmaceutical products. Using the tea residue protein high internal phase Pickering emulsion prepared by this invention to replace trans fatty acids in food preparation results in greener and healthier foods, as well as foods with longer storage and thermal stability. The tea residue protein high internal phase Pickering emulsion prepared by this invention also has broad application prospects in the food or cosmetic fields, or in the preparation of pharmaceutical products. Attached Figure Description

[0025] Figure 1 This is a flowchart illustrating the preparation method of the tea residue protein high internal phase Pickering emulsion according to the present invention;

[0026] Figure 2 This is a photograph of the tea residue protein high internal phase Pickering emulsion prepared in Example 3;

[0027] Figure 3 The graph shows a comparison of centrifugal stability (a), particle size (b), and zeta potential (c) of the tea residue protein high internal phase Pickering emulsion prepared under different ultrasonic power conditions in Example 4.

[0028] Figure 4 Comparison of appearance (a), particle size distribution (b), static rheology (c), and dynamic rheology (d) of tea residue protein high internal phase Pickering emulsions prepared under different volume ratios of primary emulsion and second camellia oil in Examples 3 and 5;

[0029] Figure 5 Comparison of appearance (a), particle size distribution (b), static rheology (c), and dynamic rheology (d) of tea residue protein high internal phase Pickering emulsions prepared under different tea residue protein suspension concentrations in Example 6;

[0030] Figure 6 Comparative graphs show the appearance, centrifugal stability (a), particle size distribution (b), emulsifying activity (c), and dynamic rheology (d) of the tea residue protein high internal phase Pickering emulsions prepared in Comparative Example 1 and Example 7.

[0031] Figure 7 Comparison of appearance (a) and particle size (b) of the tea residue protein high internal phase Pickering emulsion freshly prepared in Example 6 and the tea residue protein high internal phase Pickering emulsion prepared in Example 6 after being stored at 4°C for 30 days;

[0032] Figure 8 Comparison of appearance (a), centrifugal stability (b), particle size (c), static rheology (d), and dynamic rheology (e) of the tea residue protein high internal phase Pickering emulsion prepared in Example 7 after treatment at different temperatures for 0.5 h;

[0033] Figure 9 Centrifugal stability (a) and emulsion activity (b) of different types of protein high-inner-phase Pickering emulsions prepared using Comparative Example 1. Detailed Implementation

[0034] This invention provides a method for preparing a high-internal-phase Pickering emulsion of tea residue protein, comprising the following steps:

[0035] Tea residue protein and water are mixed to obtain a tea residue protein suspension;

[0036] The tea residue protein suspension was mixed with the first vegetable oil and ultrasonically pulverized to obtain the primary emulsion.

[0037] The primary emulsion and the second vegetable oil were mixed and sheared to obtain the tea residue protein high internal phase Pickering emulsion.

[0038] Figure 1This is a flowchart of the preparation method of the tea residue protein high internal phase Pickering emulsion of the present invention, which is described below in conjunction with... Figure 1 The preparation method of tea residue protein high internal phase Pickering emulsion is described in detail.

[0039] Unless otherwise specified, all the substances mentioned in this invention are commercially available products well known to those skilled in the art.

[0040] This invention mixes tea residue protein with water to obtain a tea residue protein suspension.

[0041] In this invention, the tea residue protein is preferably prepared using an alkaline extraction method. The alkaline extraction method for preparing tea residue protein preferably includes the following steps: mixing tea residue powder with NaOH solution, performing alkaline extraction to obtain an alkaline extract; and decolorizing the alkaline extract to obtain the tea residue protein. This invention rationally and effectively utilizes tea residue, broadening its application areas.

[0042] In this invention, the method for preparing the tea residue powder preferably includes the following steps: drying the tea residue after steeping and extracting tea leaves with boiling water to a constant weight to obtain dried tea residue; pulverizing and sieving the dried tea residue to obtain tea residue powder. In this invention, the ratio of tea leaves to boiling water is preferably 1g:(25-35)mL. In this invention, the number of times the tea leaves are steeped and extracted with boiling water is preferably ≥4 times. In this invention, the drying temperature of the extracted tea residue is preferably 60-70℃. In this invention, the mesh size of the pulverized tea residue is preferably ≤90 mesh. In this invention, the concentration of the NaOH solution is preferably 0.2-0.4mol / L, and the ratio of tea residue powder to NaOH solution is preferably 1g:(20-40)mL. In this invention, the alkali extraction preferably includes sequential water bath alkali extraction and ultrasonic alkali extraction. In this invention, the temperature of the water bath alkali extraction is preferably 85-90℃, and the time is preferably 1-2h. In this invention, the ultrasonic alkaline extraction power is preferably 250-300W, and the extraction time is preferably 1-2 hours. After alkaline extraction, this invention preferably further includes centrifuging the obtained alkaline extract and taking the supernatant as the alkaline extract. In this invention, the centrifugation speed is preferably 4500-5500 r / min, and the centrifugation time is preferably 15-40 minutes. In this invention, the decolorizing reagent is preferably an aqueous solution of H2O2, and the concentration of the H2O2 aqueous solution is preferably 3-5 g / 100 mL. In this invention, the decolorization temperature is preferably room temperature, and the decolorization time is preferably 12-24 hours. After decolorization, this invention preferably further includes: adjusting the pH of the decolorized alkaline extract to 3-5 using dilute hydrochloric acid, centrifuging to obtain a precipitate, and freeze-drying the precipitate to obtain tea residue protein. In this invention, the concentration of the dilute hydrochloric acid is preferably 0.1-0.4 mol / L. In this invention, the centrifugation speed is preferably 4500-5500 r / min, and the centrifugation time is preferably 15-40 minutes. In this invention, the freeze-drying time is preferably 45 to 55 hours.

[0043] In this invention, the water is preferably pure water or deionized water.

[0044] In this invention, the concentration of the tea residue protein suspension is 50–125 g / L, more preferably 100–120 g / L. In this invention, the mixing of the tea residue protein with water is preferably carried out at room temperature with stirring. The stirring time is preferably 2–6 h, and the stirring rate is preferably 100–500 r / min. In this invention, the pH value of the tea residue protein suspension is preferably 6–8.5, more preferably 6–8. In this invention, the pH value of the tea residue protein suspension is preferably adjusted using dilute hydrochloric acid or NaOH solution; the concentration of the dilute hydrochloric acid is preferably 0.2–0.4 mol / L, and the concentration of the NaOH solution is preferably 0.2–0.4 mol / L. This invention preferably also includes placing the tea residue protein suspension in a refrigerator at 0–4°C for 12–24 h to allow the tea residue protein to fully mix with the water.

[0045] After obtaining the tea residue protein suspension, the present invention mixes the tea residue protein suspension with a first vegetable oil and performs ultrasonic pulverization to obtain a primary emulsion.

[0046] In this invention, the first vegetable oil preferably includes one or more of camellia oil, corn oil and soybean oil, and more preferably camellia oil.

[0047] In this invention, the volume ratio of the tea residue protein suspension to the first vegetable oil is preferably 3:0.75-7, more preferably 3:4.5. In this invention, the power of the ultrasonic pulverization is preferably 285-500W, more preferably 325-425W. In this invention, the ultrasonic pulverization time is preferably 1-3 minutes, more preferably 2 minutes. In this invention, the ultrasonic pulverization is preferably performed using an ultrasonic cell disruptor.

[0048] After obtaining the primary emulsion, the present invention mixes the primary emulsion with the second vegetable oil and shears and homogenizes it to obtain the tea residue protein high internal phase Pickering emulsion.

[0049] In this invention, the first vegetable oil is preferably of the same type as the second vegetable oil, which will not be described in detail here.

[0050] In this invention, the volume ratio of the primary emulsion to the second vegetable oil is preferably 1:0.5 to 3, more preferably 1:1.5 to 2.5. In this invention, the shear homogenization time is preferably 1 to 3 minutes, more preferably 1 to 2 minutes. In this invention, the shear homogenization rate is preferably 8000 to 15000 r / min, more preferably 10000 to 14000 r / min. In this invention, the shear homogenization is preferably performed using a high-speed disperser.

[0051] This invention provides a high-internal-phase Pickering emulsion of tea residue protein prepared by the above-described method. In this invention, the high-internal-phase Pickering emulsion of tea residue protein comprises tea residue protein, vegetable oil, and water. In this invention, the high-internal-phase Pickering emulsion of tea residue protein is an O / W system. In this invention, the vegetable oil is one of the first vegetable oil or the second vegetable oil. In this invention, the volume fraction of the oil phase in the high-internal-phase Pickering emulsion of tea residue protein is preferably 75-88%, more preferably 85-88%; the concentration of tea residue protein in the high-internal-phase Pickering emulsion of tea residue protein is preferably 5-17.5 g / L, more preferably 12.5-17.5 g / L.

[0052] This invention also provides the application of the tea residue protein high internal phase Pickering emulsion described above in the food or cosmetic fields or in the preparation of pharmaceutical products.

[0053] In this invention, there are no special requirements for the application of the tea residue protein high internal phase Pickering emulsion in the food or cosmetic fields or in the preparation of pharmaceutical products; it can be done in accordance with the methods commonly used by those skilled in the art.

[0054] To further illustrate the present invention, the preparation method and application of the tea residue protein high internal phase Pickering emulsion provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0055] Example 1

[0056] Preparation of tea residue protein

[0057] Tea leaves were dispersed in boiling water at a ratio of 1g:30ml and extracted for 15 minutes. The extract was collected using a filter cloth. The extraction process was repeated 5 times, and the tea residue after the last extraction was collected. The tea residue was dried at 65℃ to constant weight, then pulverized and passed through an 80-mesh sieve to obtain tea residue powder. The tea residue powder was mixed with 0.3mol / L NaOH solution at a ratio of 1g:30mL and heated in a 90℃ water bath for 1.5 hours for water bath alkali extraction. Subsequently, ultrasonic alkali extraction was performed at 285W ultrasonic power for 1 hour. The ultrasonically extracted alkali extract was then centrifuged at 5000r / min for 20 minutes, and the supernatant was collected as the alkali extract. 4g / 100mL of H2O2 aqueous solution was added to the alkali extract, and the mixture was left to stand for 24 hours for decolorization. The pH of the decolorized alkali extract was adjusted to 3.5 using dilute hydrochloric acid. The pH-adjusted alkaline extract was then placed back into a centrifuge and centrifuged at 5000 rpm for 20 minutes to obtain a precipitate. The precipitate was freeze-dried for 48 hours to obtain tea residue protein, which was then sealed and stored at 4°C for later use.

[0058] Example 2

[0059] Preparation of tea residue protein suspension

[0060] Weigh the tea residue protein obtained in Example 1, and magnetically stir the tea residue protein suspension with a mass concentration of 60 g / L at 300 r / min for 4 h at room temperature to obtain a tea residue protein suspension. Adjust the pH of the tea residue protein suspension to 7 using 0.2 mol / L NaOH solution. Then place the tea residue protein suspension in a refrigerator at 4°C for 24 h to allow the tea residue protein to fully mix with water for later use.

[0061] Example 3

[0062] Preparation of tea residue protein high internal phase Pickering emulsion

[0063] The tea residue protein suspension from Example 2 and the first camellia oil were mixed at a volume ratio of 3:4.5. The ultrasonic power of the ultrasonic cell disruptor was adjusted to 380W, and the mixture was ultrasonically disrupted for 2 minutes to obtain the primary emulsion.

[0064] The primary emulsion and the second camellia oil were mixed at a volume ratio of 1:0.6, and homogenized using a high-speed disperser at a rate of 13600 r / min for 2 min to obtain a high-internal-phase Pickering emulsion of tea residue protein with an oil phase volume fraction of 75%. Figure 2 As shown, Figure 2 This is a photograph of the tea residue protein high internal phase Pickering emulsion prepared in Example 3. From... Figure 2 It can be seen that the tea residue protein high internal phase emulsion prepared under these conditions is milky white in color, with no emulsification or oil separation, and has good stability but strong fluidity.

[0065] Example 4

[0066] Tea residue protein high internal phase Pickering emulsion prepared under different ultrasonic power conditions

[0067] The preparation method of the tea residue protein high internal phase Pickering emulsion is the same as in Example 3, the only difference being that the ultrasonic power was adjusted to 285W, 332.5W, 380W, 427.5W, and 475W respectively, resulting in tea residue protein high internal phase Pickering emulsions as shown in Example 3. Figure 3 As shown. Figure 3 This is a comparison of the centrifugal stability (a), particle size (b), and zeta potential (c) of the tea residue protein high internal phase Pickering emulsion prepared under different ultrasonic power conditions in Example 4. Figure 3 It can be seen that when the ultrasonic power is 380W, the emulsion does not separate into layers after centrifugation, the emulsion particle size reaches its minimum, and the absolute value of the Zeta potential is the highest. This indicates that the tea residue protein high internal phase Pickering emulsion prepared under this ultrasonic power has the best stability. Therefore, 380W is the optimal ultrasonic power.

[0068] Example 5

[0069] Tea residue protein high-inner-phase Pickering emulsion prepared under different volume ratios of colostrum and second camellia oil

[0070] The preparation method of the tea residue protein high internal phase Pickering emulsion is the same as in Example 3, the only difference being that the volume ratio of the primary emulsion and the second camellia oil is adjusted to 1:1, 3:4, 3:5, and 3:7, respectively, resulting in oil phase volumes of 80%, 83%, 85%, and 88% for the obtained tea residue protein high internal phase Pickering emulsions. The obtained tea residue protein high internal phase Pickering emulsion is as follows... Figure 4 As shown. Figure 4 The images show a comparison of the appearance (a), particle size distribution (b), static rheology (c), and dynamic rheology (d) of the high internal phase Pickering emulsions of tea residue protein prepared in Examples 3 (75%) and 5 under different volume ratios of primary emulsion to second camellia oil. Figure 4 It can be seen that: Figure 4 As can be seen in (a), when the oil phase volume of the tea residue protein high internal phase Pickering emulsion is ≥85%, no flow occurs after inversion. Figure 4 (c) and Figure 4 (d) shows that when the oil phase volume is ≥80%, the elastic modulus G' > the viscous modulus G, indicating that at this time, the tea residue protein high internal phase Pickering emulsion forms a gel-like structure dominated by the elastic modulus. Figure 4 (b) shows that when the oil phase volume is 88%, a peak appears in the particle size of the tea residue protein high internal phase Pickering emulsion between 20 and 100 μm, indicating the presence of large oil droplets in the tea residue protein high internal phase Pickering emulsion. The tea residue protein high internal phase Pickering emulsion has undergone demulsification, resulting in emulsion instability. Therefore, an oil phase volume fraction of 85% is adopted as the optimal oil phase volume fraction.

[0071] Example 6

[0072] Tea residue protein high internal phase Pickering emulsion prepared under different tea residue protein suspension concentrations

[0073] Tea residue protein suspensions were prepared according to the preparation method in Example 2, with the following differences: the concentrations of the tea residue protein suspensions were 50 g / L, 66.7 g / L, 83.3 g / L, 100 g / L and 116.7 g / L, respectively.

[0074] The preparation method of the tea residue protein high internal phase Pickering emulsion is the same as in Example 3, the difference being that the volume ratio of the primary emulsion to the second camellia oil is 3:5, and the oil phase volume of the resulting tea residue protein high internal phase Pickering emulsion is 85%. Tea residue protein high internal phase Pickering emulsions were prepared using tea residue protein suspensions of different concentrations, as follows: Figure 5 As shown, Figure 5The images show a comparison of the appearance (a), particle size distribution (b), static rheological diagram (c), and dynamic rheological diagram (d) of the high internal phase Pickering emulsions of tea residue protein prepared under different tea residue protein suspension concentrations in Example 6. Figure 5 It can be seen that: Figure 5 As can be seen from (a) above, when the concentration of the tea residue protein suspension is ≥100 g / L, the tea residue protein high internal phase Pickering emulsion does not flow after inversion. Figure 5 (b) shows that when the concentration of the tea residue protein suspension is ≥100 g / L, the particle size of the tea residue protein high internal phase Pickering emulsion is significantly reduced. Figure 5 (c) shows that the viscosity of the tea residue protein high internal phase Pickering emulsion decreases with increasing shear rate at different tea residue protein suspension concentrations, indicating that the prepared tea residue protein high internal phase Pickering emulsion is a non-Newtonian fluid exhibiting shear thinning. Figure 5 (d) shows that when the concentration of the tea residue protein suspension is ≥66.7 g / L, the tea residue protein high internal phase Pickering emulsion has a gel-like structure with elasticity as the main component. As the ratio of tea residue protein to deionized water increases, the viscosity of the tea residue protein high internal phase Pickering emulsion increases. When the concentration of the tea residue protein suspension is 100 g / L and 116.7 g / L, the viscosity of the tea residue protein high internal phase Pickering emulsion does not differ significantly. Considering the need to save raw materials, a tea residue protein suspension concentration of 100 g / L is selected as the optimal ratio.

[0075] Based on the results obtained in Examples 1 to 6, the final preferred results are: ultrasonic power of 380W, oil phase volume fraction of 85%, and tea residue protein suspension concentration of 100g / L.

[0076] Example 7

[0077] The preparation method of the tea residue protein suspension is the same as in Example 2, except that the concentration of the tea residue protein suspension is 100 g / L; the preparation method of the tea residue protein high internal phase Pickering emulsion is the same as in Example 3, except that the volume ratio of the primary emulsion to the second camellia oil is 3:5.

[0078] The resulting tea residue protein high internal phase Pickering emulsion had an oil phase volume fraction of 85% and a tea residue protein concentration of 15 g / L.

[0079] Comparative Example 1

[0080] One-step emulsion method

[0081] The tea residue protein suspension prepared in Example 2 was mixed with camellia oil at a volume ratio of 3:17 and homogenized by shearing at a rate of 13600 r / min for 2 min using a high-speed disperser to obtain a tea residue protein high internal phase Pickering emulsion with an oil phase volume fraction of 85%. Figure 6 As shown, Figure 6 The images show a comparison of the appearance, centrifugal stability (a), particle size distribution (b), emulsifying activity (c), and dynamic rheology (d) of the tea residue protein high internal phase Pickering emulsions prepared in Comparative Example 1 (one-step) and Example 7 (two-step). Figure 6 It can be seen that: Figure 6 (a) shows that the color of the tea residue protein high internal phase Pickering emulsion prepared by the two-step emulsification method of ultrasonic disruption and shear homogenization in Example 7 is significantly lighter than that of the tea residue protein high internal phase Pickering emulsion obtained by the one-step emulsification method in Comparative Example 1, indicating that the tea residue protein is emulsified more thoroughly. Figure 6 The centrifugal stability of (a) in Example 7 shows that the emulsion prepared by the two-step emulsification method is more stable and no water is separated after centrifugation, while the emulsion prepared by the one-step emulsification method in Comparative Example 1 not only has water separated, but also shows stratification. This indicates that the preparation method provided by the present invention improves the emulsification stability of the emulsion. Figure 6 (b) shows that the particle size of the emulsion prepared by the two-step emulsification method in Example 7 is significantly reduced compared to the one-step emulsification method in Comparative Example 1. Figure 6 (c) indicates that Example 7 uses a two-step emulsification method to improve the emulsifying activity of tea residue protein, demonstrating that the preparation method provided by the present invention can effectively improve the emulsifying performance of tea residue protein. Figure 6 (d) indicates that the elastic modulus G' of the emulsion prepared by the one-step emulsification method in Comparative Example 1 is less than the viscous modulus G", indicating that the emulsion formed is mainly viscous, with strong fluidity and reduced emulsion stability. In contrast, the elastic modulus G' of the emulsion prepared by the two-step emulsification method in Example 7 is significantly higher than the viscous modulus G", indicating that a gel-like structure with elasticity as the main component is formed. The preparation method provided by this invention can improve the viscoelasticity of the tea residue protein high internal phase Pickering emulsion, thereby obtaining a tea residue protein high internal phase Pickering emulsion with higher storage stability and thermal stability.

[0082] Application Example 1

[0083] Storage stability of tea residue protein high internal phase Pickering emulsion

[0084] The tea residue protein high internal phase Pickering emulsion sample prepared in Example 6 was placed in a 4°C refrigerator for 30 days. The appearance and particle size changes of the sample before and after 30 days of storage were measured. Each sample was tested three times, and the results are as follows: Figure 7 As shown. Figure 7 This is a comparison of the appearance (a) and particle size (b) of the tea residue protein high internal phase Pickering emulsion prepared in Example 6 and the tea residue protein high internal phase Pickering emulsion prepared in Example 6 after storage at 4°C for 30 days. Figure 7 It can be seen that: Figure 7(a) shows that the appearance of the tea residue protein high internal phase Pickering emulsion prepared in Example 6 after 30 days of storage was not significantly different from that of the freshly prepared emulsion, and no emulsion separation or oil separation occurred. Figure 7 (b) shows that, except for the tea residue protein suspension with a concentration of 50 g / L, which showed an increase in particle size after 30 days, the particle size of the other tea residue protein high internal phase Pickering emulsions did not change much, indicating that the tea residue protein high internal phase Pickering emulsion prepared in this invention has good storage stability.

[0085] Application Example 2

[0086] Thermal stability of tea residue protein high internal phase Pickering emulsion

[0087] The tea residue protein high internal phase Pickering emulsion samples prepared in Example 7 were placed in water baths at 25°C, 55°C, 70°C, 85°C, and 100°C and heated for 30 min each. After cooling, they were placed at room temperature for 24 h. The appearance, particle size, and rheological properties of each sample before and after heat treatment were recorded. Each sample was tested three times, and the results are shown below. Figure 8 As shown. Figure 8 The images show a comparison of the appearance (a), centrifugal stability (b), particle size (c), static rheology (d), and dynamic rheology (e) of the tea residue protein high internal phase Pickering emulsion prepared in Example 7 after treatment at different temperatures for 0.5 h. Figure 8 It can be seen that: Figure 8 (a), (b), and (c) show that the appearance, centrifugal stability, and particle size of the tea residue protein high internal phase Pickering emulsion did not change significantly after treatment at different temperatures. Figure 8 (d) and (e) in the figure show that the increase in temperature improves the viscoelasticity of the tea residue protein high internal phase Pickering emulsion, indicating that the tea residue protein high internal phase Pickering emulsion prepared by the present invention has good thermal stability.

[0088] Application Comparative Example 1

[0089] High-internal-phase Pickering emulsions were prepared according to the preparation method of Example 7, the difference being that the proteins used were bovine serum albumin, whey protein, tea residue protein, soy protein isolate, and pea protein, respectively. The high-internal-phase Pickering emulsions obtained from different types of proteins are shown below. Figure 9 . Figure 9 Centrifugal stability (a) and emulsion activity (b) of different types of protein high-inner-phase Pickering emulsions prepared using Comparative Example 1.

[0090] from Figure 9As shown in (a), the high internal phase Pickering emulsion prepared using soy protein isolate and pea protein exhibited water separation and stratification, while the high internal phase Pickering emulsion prepared using tea residue protein, whey protein, and bovine serum albumin did not show water separation. This indicates that the stability of the tea residue protein high internal phase Pickering emulsion is similar to that of the animal protein high internal phase Pickering emulsion, and significantly higher than that of the high internal phase Pickering emulsion prepared using other plant proteins. Figure 9 As shown in (b), the emulsifying activity of the high-internal-phase Pickering emulsion made from tea residue protein is significantly higher than that made from soybean protein isolate and pea protein, and even higher than that made from whey protein and bovine serum albumin. Higher emulsifying activity indicates more thorough emulsification, suggesting better emulsification by the protein used, and thus higher stability in the high-internal-phase Pickering emulsion prepared using this protein as an emulsifier. Therefore, the emulsifying activity of the tea residue protein high-internal-phase Pickering emulsion is comparable to that of animal protein high-internal-phase Pickering emulsions, and the resulting tea residue protein high-internal-phase Pickering emulsion exhibits superior stability.

[0091] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a tea residue protein high internal phase Pickering emulsion, characterized in that, Includes the following steps: Tea residue protein is mixed with water to obtain a tea residue protein suspension; the concentration of the tea residue protein suspension is 100~120g / L. The tea residue protein suspension and the first vegetable oil are mixed and ultrasonically pulverized to obtain a primary emulsion; the volume ratio of the tea residue protein suspension to the first vegetable oil is 3:4.5; the ultrasonic pulverization power is 325~425W. The primary emulsion and the second vegetable oil are mixed and sheared to obtain the tea residue protein high internal phase Pickering emulsion; the volume ratio of the primary emulsion to the second vegetable oil is 1:1.5~2.

5. The volume fraction of the oil phase in the tea residue protein high internal phase Pickering emulsion is 85-88%.

2. The preparation method according to claim 1, characterized in that, The pH value of the tea residue protein suspension is 6~8.

5.

3. The preparation method according to claim 1, characterized in that, The first and second vegetable oils each include one or more of camellia oil, corn oil, and soybean oil.

4. The preparation method according to claim 1, characterized in that, The ultrasonic pulverization time is 1-3 minutes.

5. The preparation method according to claim 1, characterized in that, The shear homogenization time is 1-3 min, and the shear homogenization rate is 8000-15000 r / min.

6. The tea residue protein high internal phase Pickering emulsion prepared by the preparation method according to any one of claims 1 to 5, characterized in that, The tea residue protein high internal phase Pickering emulsion comprises: tea residue protein, vegetable oil and water; the tea residue protein high internal phase Pickering emulsion is an O / W system; the volume fraction of the oil phase in the tea residue protein high internal phase Pickering emulsion is 85-88%; the vegetable oil is the first vegetable oil and the second vegetable oil.

7. The tea residue protein high internal phase Pickering emulsion according to claim 6, characterized in that, The concentration of tea residue protein in the high internal phase Pickering emulsion is 5~17.5 g / L.

8. The tea residue protein high internal phase Pickering emulsion prepared by the preparation method according to any one of claims 1 to 5, or the tea residue protein high internal phase Pickering emulsion according to any one of claims 6 to 7, in the food or cosmetic field or in the preparation of pharmaceutical products.

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