High-concentration phytosterol micro-nano powder capable of being uniformly distributed in an aqueous phase and a preparation method thereof

Abstract

The present application belongs to the technical field of phytosterol preparation, and particularly relates to a high-concentration phytosterol micro-nano powder capable of being uniformly distributed in an aqueous phase and a preparation method thereof. The preparation method comprises the following steps: first, dissolving phytosterol and lecithin in an organic solvent, dissolving whey protein isolate in water, and mixing the two by means of a high-speed shearing machine to obtain a mixed solution; removing the organic solvent by means of rotary evaporation, and performing spray drying to obtain the high-concentration phytosterol micro-nano powder product capable of being uniformly distributed in the aqueous phase. The phytosterol content of the phytosterol micro-nano powder product prepared by the present application can reach 70%, the preparation process is short in time consumption, high in efficiency, good in product reconstitution, simple in operation, and capable of being industrialized, and the product can be well applied to food and medicine, and the bioavailability and added value of phytosterol can be improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of phytosterol preparation, and particularly relates to a high-concentration phytosterol micro-nano powder capable of being uniformly distributed in an aqueous phase and a preparation method thereof. BACKGROUND

[0002] Phytosterol is an active compound containing 28 or 29 carbon alcohols, which is widely present in plants. It is recognized by the US Food and Drug Administration (FDA) as a new raw material of natural health food for "reducing blood lipids and preventing arteriosclerosis", and is also one of the top ten functional nutrients recommended by the International Nutrition Society. However, phytosterol is not soluble in water, and its solubility in oil is only about 1%, making it difficult to add to food substrates and difficult to be absorbed by the human body, which greatly limits its application in the food industry.

[0003] At present, the methods for improving the water solubility of phytosterol mainly include nanoemulsions prepared by using gum arabic, liposomes, cyclodextrin and protein as wall materials. However, although the current research methods improve the water solubility of phytosterol, the phytosterol content of the phytosterol nanoemulsion prepared by these methods is low. The phytosterol content of the nanoemulsion in patent CN109674053A, a weight-reducing and lipid-lowering phytosterol nanoemulsion and a preparation method thereof, is 0.5-4%, and the phytosterol content in dry weight is 1-10%. The phytosterol content of the nano-aqueous gel emulsion in patent CN110279123B, a preparation method of a water-soluble phytosterol nano-aqueous gel emulsion, is 1.7%, and the phytosterol content in dry weight is 1-5%. The phytosterol content of the emulsion in patent CN110946285B, a preparation method of a water-in-oil Pickering emulsion based on phytosterol stabilization, is 2%, and the phytosterol content in dry weight of the emulsion is less than 10%.

[0004] Through consulting relevant literature, it can be found that the water-soluble phytosterol powder has not been studied in terms of subsequent product development and taste. By consulting existing authorized patents (see Table 1 for related authorized patents of water-soluble phytosterol powder), it can be found that the sterol content of the existing water-soluble phytosterol powder is less than 20%, and the reconstitution of the powder has not been studied. Through market research, it can be found that only one product with 66% sterol is available on the market, and the solubility is general, which can form obvious aggregates and affect the sense of taste. Therefore, it is urgent to develop a method for preparing a water-soluble phytosterol powder with simple preparation, good water solubility and high content.

[0005] Table 1: Authorized patents of existing water-soluble phytosterol powder

[0006] SUMMARY

[0007] In view of the deficiencies of the prior art, the present application provides a high-concentration and uniformly distributed plant sterol micro-nano powder in an aqueous phase and a preparation method thereof, which is not only efficient, low in energy consumption, short in time consumption and simple in steps, but also high in plant sterol powder content, good in solubility and good in flavor.

[0008] The present application provides a preparation method of a high-concentration and uniformly distributed plant sterol micro-nano powder in an aqueous phase, comprising the following preparation steps:

[0009] (1) Dissolve whey protein isolate in deionized water according to a mass ratio of (0.1-1):100, and magnetically stir until fully dissolved to obtain an aqueous solution;

[0010] (2) Prepare an organic solvent by mixing n-hexane, anhydrous ethanol and ethyl acetate according to a certain mass percentage;

[0011] (3) Dissolve plant sterol and lecithin in the organic solvent prepared in step (2) according to mass ratios of (0.1-1):100 and (0.125-1):100, respectively, and fully dissolve them by magnetic stirring and ultrasonic oscillation to obtain a plant sterol solution;

[0012] (4) Add the plant sterol solution obtained in step (3) to the aqueous solution obtained in step (1) according to a mass ratio of (0.01-1):1, and then perform high-speed shearing to obtain a mixed emulsion;

[0013] (5) Remove the organic solvent from the mixed emulsion obtained in step (4) by rotary evaporation, and perform spray drying to obtain a plant sterol micro-nano powder.

[0014] The present application uses whey protein isolate as a wall material, lecithin as an emulsifier, and plant sterol as a core material dissolved in an organic phase, and combines a high-speed shearing method to rapidly disperse the tiny plant sterol solution in the whey protein system, further removes the organic solvent by rotary evaporation, and the whey protein effectively wraps the tiny plant sterol during the process, plays a dispersing role, prevents the aggregation and precipitation of sterol, and finally obtains a plant sterol micro-capsule powder by spray drying.

[0015] Preferably, in step (1) of the above technical solution, the aqueous solution is configured by whey protein isolate, and the mass ratio of the whey protein isolate to deionized water is (0.1-0.5):10; the rotating speed of magnetic stirring is 400-1000 rpm, and the time is 10-30 min.

[0016] Preferably, in the step (2), the mass percentage of the n-hexane, the absolute ethyl alcohol and the ethyl acetate is 5-100%, 5-100% and 5-100% respectively.

[0017] Preferably, in the step (3), the stirring speed is 800-1000 rpm, the stirring time is 5-10 min; the ultrasonic is pulse ultrasonic, 1 s for each time, 1 s interval, the power is 500-800 w, and the ultrasonic time is 5-20 min.

[0018] Preferably, in the step (4), the mass ratio of the phytosterol solution to the aqueous solution is (0.05-1) : 1.

[0019] Preferably, in the step (4), the speed of the high-speed shearing machine is 10000-18000 rpm, and the shearing time is 3-5 min.

[0020] Preferably, in the step (4), the speed of the high-speed shearing machine is 12000 rpm, and the shearing time is 4 min.

[0021] Preferably, in the step (5), the rotary evaporation temperature is 40-50 DEG C, the vacuum degree is 0.08-0.1 Mpa, and the speed is 40-60 rpm; preferably, the rotary evaporation temperature is 45 DEG C, and the speed is 60 rpm.

[0022] Preferably, in the step (5), when the spray drying is performed, the inlet temperature is 140-180 DEG C, and the outlet temperature is 60-100 DEG C.

[0023] Another aspect of the present application also provides a high-concentration phytosterol micro-nano powder which can be uniformly distributed in an aqueous phase and is prepared by the above preparation method, and the phytosterol content is more than 70%.

[0024] The beneficial effects of the present application relative to the prior art are as follows:

[0025] 1. The whey protein isolate and lecithin used in the present application are food grade, widely used in the food industry, and have certain nutritional value, good functionality, non-toxicity and low cost.

[0026] 2. The organic solvent used in the present application can be reused by rotary evaporation, which reduces the production cost and meets the national policy of sustainable production.

[0027] 3. The high-concentration phytosterol micro-nano powder product prepared by the present application has good water solubility, high embedding rate, good re-dissolution in water and can be uniformly distributed in the aqueous phase, and can be used as a food base for the production of functional food.

[0028] 4、The production method has the characteristics of simple production process, safety, low requirement, and is a green production technology, and is suitable for large-scale production. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 Comparison chart of the mixed emulsion prepared in Examples 1-5;

[0030] Figure 2 Comparison chart of the powder obtained by spray drying of Examples 1-5 and phytosterol;

[0031] Figure 3 Comparison chart of the phytosterol powder of Examples 1-5 and phytosterol reconstitution;

[0032] Figure 4 Comparison chart of the 70% sterol content of Example and the powder of the highest sterol content (66%) product on the market;

[0033] Figure 5 Comparison chart of the 70% sterol content of Example and the reconstitution of the highest sterol content (66%) product on the market. DETAILED DESCRIPTION

[0034] The above technical features of the present application and the technical features described in detail below (such as the examples) can be combined with each other to form new or preferred technical solutions, but the present application is not limited to these examples, and these examples do not limit the present application in any way.

[0035] The experimental methods in the following examples are all conventional methods unless otherwise specified. The preparations involved in the following examples are all ordinary commercially available products unless otherwise specified, and can be purchased on the market.

[0036] The present application will be further described in detail below in combination with the drawings and examples:

[0037] Example 1

[0038] A preparation method of a high-concentration and uniformly distributed phytosterol micro-nano powder in an aqueous phase, comprising the following preparation steps:

[0039] (1) Under the conditions of room temperature and magnetic stirring (speed 1000 rpm, time 30 min), whey protein isolate was dispersed and dissolved in deionized water according to the mass ratio (1:24) to obtain an aqueous solution;

[0040] (2) Prepare an organic solvent by mixing n-hexane, anhydrous ethanol and ethyl acetate according to the mass percentage (20%:30%:50%);

[0041] (3) Dissolve phytosterol and lecithin in the prepared organic solvent respectively according to the mass ratio (1:7) and (1:21), and make them fully dissolved by magnetic stirring and ultrasonic oscillation to obtain a phytosterol solution; wherein the magnetic stirring speed is 800 rpm, and the stirring time is 5 min;

[0042] (4) Add the phytosterol solution to the aqueous solution according to the mass ratio (1:4), and then perform high-speed shearing (12000 rpm, 4 min) to obtain a mixed emulsion;

[0043] (5) Remove the organic solvent from the obtained mixed emulsion by rotary evaporation (temperature 45°C, speed 60 rpm), and spray dry (inlet temperature 160°C, outlet temperature 80°C) to obtain a phytosterol micro-nano powder.

[0044] Test:

[0045] The particle size of the emulsion in step (4) is measured, and the particle size is 846.63±117.58 nm, the PDI is 0.81±0.03, and the Zeta potential is 16.83±6.53 mV.

[0046] The embedding rate and loading rate of the phytosterol powder in step (5) are determined, and the embedding rate of phytosterol is 93.47%, and the loading amount is 375 mg of phytosterol per gram of solid. Finally, a phytosterol micro-nano powder with a content of 37.5% is prepared.

[0047] Example 2

[0048] A method for preparing a high-concentration phytosterol micro-nano powder that can be uniformly distributed in an aqueous phase, comprising the following preparation steps:

[0049] (1) Under the conditions of room temperature and magnetic stirring (speed 1000 rpm, time 30 min), disperse and dissolve whey protein isolate in deionized water according to the mass ratio (1:32) to obtain an aqueous solution;

[0050] (2) Prepare an organic solvent by mixing n-hexane, anhydrous ethanol, and ethyl acetate according to the mass percentage (20%:30%:50%);

[0051] (3) Dissolve phytosterol and lecithin in the prepared organic solvent respectively according to the mass ratio (1:7) and (1:21), and make them fully dissolved by magnetic stirring and ultrasonic oscillation to obtain a phytosterol solution; wherein the magnetic stirring speed is 800 rpm, and the stirring time is 5 min;

[0052] (4) Add the phytosterol solution to the aqueous solution according to the mass ratio (1:4), and then perform high-speed shearing (12000 rpm, 4 min) to obtain a mixed emulsion;

[0053] (5) The obtained mixed emulsion was removed of organic solvent by rotary evaporation (temperature 45°C, rotation speed 60 rpm) and spray drying (inlet temperature 160°C, outlet temperature 80°C) to obtain phytosterol micro-nano powder.

[0054] Test:

[0055] The particle size of the emulsion in step (4) was measured, and the particle size was 878.67 ± 138.4 nm, the PDI was 0.82 ± 0.11, and the Zeta potential was 19.1 ± 1.65 mV.

[0056] The embedding rate and loading rate of the phytosterol powder in step (5) were determined, and the embedding rate of phytosterol was 93.01%, and the loading amount was 428 mg of phytosterol per gram of solid. The final content of the phytosterol powder was 42.8%.

[0057] Example 3

[0058] A method for preparing a high-concentration and uniformly distributed phytosterol micro-nano powder in an aqueous phase, comprising the following preparation steps:

[0059] (1) Under the conditions of room temperature and magnetic stirring (rotation speed 1000 rpm, time 30 min), whey protein isolate was dispersed and dissolved in deionized water according to the mass ratio (1:49) to obtain an aqueous solution;

[0060] (2) Prepare an organic solvent by mixing n-hexane, anhydrous ethanol, and ethyl acetate according to the mass percentage (20%:30%:50%);

[0061] (3) Dissolve phytosterol and lecithin in the prepared organic solvent according to the mass ratio (1:7) and (1:21), respectively, and fully dissolve them by magnetic stirring and ultrasonic oscillation to obtain a phytosterol solution; wherein the magnetic stirring speed is 800 rpm, and the stirring time is 5 min;

[0062] (4) Add the phytosterol solution to the aqueous solution according to the mass ratio (1:4), and then pass through high-speed shearing (12000 rpm, 4 min) to obtain a mixed emulsion;

[0063] (5) The obtained mixed emulsion was removed of organic solvent by rotary evaporation (temperature 45°C, rotation speed 60 rpm) and spray drying (inlet temperature 160°C, outlet temperature 80°C) to obtain phytosterol micro-nano powder.

[0064] Test:

[0065] The particle size of the emulsion in step (4) was measured, and the particle size was 862.13±176.26 nm, the PDI was 0.9±0.09, and the Zeta potential was 37.53±2.97 mV. In the aqueous phase, when the absolute value of the Zeta potential is greater than 30 mV, it is considered that the dispersion system is relatively stable, so the dispersion system prepared in this example is in a stable state.

[0066] The embedding rate and loading rate of the phytosterol powder in step (5) were measured, and the embedding rate of phytosterol was 92.26%, and the loading amount was 500 mg of phytosterol per gram of solid. Finally, a phytosterol powder with a content of 50% was prepared.

[0067] Example 4

[0068] A method for preparing a high-concentration and uniformly distributed phytosterol micro-nano powder in an aqueous phase, comprising the following preparation steps:

[0069] (1) Under the conditions of room temperature and magnetic stirring (speed 1000 rpm, time 30 min), whey protein isolate was dispersed and dissolved in deionized water according to the mass ratio (1:99) to obtain an aqueous solution;

[0070] (2) Prepare an organic solvent by mixing n-hexane, anhydrous ethanol, and ethyl acetate according to the mass percentage (20%:30%:50%);

[0071] (3) Dissolve phytosterol and lecithin in the prepared organic solvent according to the mass ratio (1:7) and (1:21), respectively, and fully dissolve them by magnetic stirring and ultrasonic oscillation to obtain a phytosterol solution; wherein the magnetic stirring speed is 800 rpm, and the stirring time is 5 min;

[0072] (4) Add the phytosterol solution to the aqueous solution according to the mass ratio (1:4), and then perform high-speed shearing (12000 rpm, 4 min) to obtain a mixed emulsion;

[0073] (5) Remove the organic solvent from the obtained mixed emulsion by rotary evaporation (temperature 45°C, speed 60 rpm), and spray dry (inlet temperature 160°C, outlet temperature 80°C) to obtain a phytosterol micro-nano powder.

[0074] Test:

[0075] The particle size of the emulsion in step (4) was measured, and the particle size was 509.17±139.42 nm, the PDI was 0.54±0.07, and the Zeta potential was 40.03±1.96 mV. In the aqueous phase, when the absolute value of the Zeta potential is greater than 30 mV, it is considered that the dispersion system is relatively stable, so the dispersion system prepared in this example is in a stable state.

[0076] The plant sterol powder in step (5) was subjected to embedding rate and loading rate determination, and the embedding rate of the plant sterol was 91.13%, and the loading amount was 600 milligrams of plant sterol per gram of solid. A plant sterol powder with a content of 60% was finally prepared.

[0077] Example 5

[0078] A method for preparing a plant sterol micro-nano powder with high concentration and uniform distribution in an aqueous phase, comprising the following preparation steps:

[0079] (1) Under the conditions of room temperature and magnetic stirring (speed 1000 rpm, time 30 min), whey protein isolate was dispersed and dissolved in deionized water according to the mass ratio (1:99) to obtain an aqueous solution;

[0080] (2) The organic solvent was prepared by mixing n-hexane, anhydrous ethanol and ethyl acetate according to the mass percentage (20%:30%:50%);

[0081] (3) The plant sterol and lecithin were dissolved in the prepared organic solvent according to the mass ratio (1:7.3) and (1:34.3) respectively, and were fully dissolved by magnetic stirring and ultrasonic oscillation, to obtain a plant sterol solution; wherein the magnetic stirring speed was 800 rpm, and the stirring time was 5 min;

[0082] (4) The plant sterol solution was added to the aqueous solution according to the mass ratio (1:3.2), and then high-speed shearing (12000 rpm, 4 min) was performed to obtain a mixed emulsion;

[0083] (5) The obtained mixed emulsion was subjected to rotary evaporation (temperature 45℃, speed 60 rpm) to remove the organic solvent, and spray drying (inlet temperature 160℃, outlet temperature 80℃) to obtain a plant sterol micro-nano powder.

[0084] Test:

[0085] The particle size of the emulsion in step (4) was determined, and the particle size was 476.17±174.52 nm, the PDI was 0.47±0.13, and the Zeta potential was 42.13±2.54 mV. When the absolute value of the Zeta potential in the aqueous phase is greater than 30 mV, it is considered that the dispersion system is relatively stable, so the dispersion system prepared in this example is in a stable state.

[0086] The plant sterol powder in step (5) was subjected to embedding rate and loading rate determination, and the embedding rate of the plant sterol was 88.24%, and the loading amount was 700 milligrams of plant sterol per gram of solid. A plant sterol powder with a content of 70% was finally prepared.

[0087] Comparative Example 1

[0088] A preparation method of a phytosterol micro-nano powder, comprising the following preparation steps:

[0089] (1) Under the conditions of normal temperature and magnetic stirring (rotation speed 1000 rpm, time 30 min), malt dextrin, whey protein isolate, sodium caseinate or gum arabic were dispersed and dissolved in deionized water according to the mass ratio (1:24) to obtain an aqueous solution;

[0090] (2) Phytosterol and lecithin were dissolved in the prepared aqueous solution according to the mass ratios (1:21) and (1:82), respectively, and a phytosterol solution was obtained by high-speed shearing.

[0091] Test:

[0092] Phytosterol cannot be dissolved in an aqueous solution, and a mixed emulsion cannot be obtained by embedding.

[0093] Comparative Example 2

[0094] A preparation method of a phytosterol micro-nano powder, comprising the following preparation steps:

[0095] (1) Under the conditions of normal temperature and magnetic stirring (rotation speed 1000 rpm, time 30 min), malt dextrin was dispersed and dissolved in deionized water according to the mass ratio (1:24) to obtain a malt dextrin solution;

[0096] (2) n-hexane, anhydrous ethanol and ethyl acetate were selected and configured into an organic solvent according to the mass percentage (20%:30%:50%);

[0097] (3) Phytosterol and lecithin were dissolved in the prepared organic solvent according to the mass ratios (1:7) and (1:21), respectively, and a phytosterol solution was obtained by stirring and ultrasonic oscillation to fully dissolve; wherein the magnetic stirring speed was 800 rpm, and the stirring time was 5 min;

[0098] (4) The phytosterol solution was added to the malt dextrin solution according to the mass ratio (1:4), and a mixed emulsion was obtained by high-speed shearing (12000 rpm, 4 min).

[0099] Test:

[0100] The mixed emulsion cannot form a uniform emulsion after standing and layering, so the subsequent spray drying is not performed.

[0101] Comparative Example 3

[0102] A preparation method of a phytosterol micro-nano powder, comprising the following preparation steps:

[0103] (1) Under the condition of normal temperature and magnetic stirring (speed 1000 rpm, time 30 min), sodium caseinate is dispersed and dissolved in deionized water according to the mass ratio (1:24) to obtain a sodium caseinate solution;

[0104] (2) Select n-hexane, anhydrous ethanol and ethyl acetate to configure an organic solvent according to the mass percentage (20%:30%:50%);

[0105] (3) Plant sterols and lecithin are respectively dissolved in the prepared organic solvent according to the mass ratio (1:7) and (1:21), and are fully dissolved by stirring and ultrasonic oscillation, so as to obtain a plant sterol solution; wherein the magnetic stirring speed is 800 rpm, and the stirring time is 5 min;

[0106] (4) The plant sterol solution is added to the sodium caseinate solution according to the mass ratio (1:4), and a mixed emulsion is obtained by high-speed shearing (12000 rpm, 4 min).

[0107] Test:

[0108] The mixed emulsion cannot form a uniform emulsion after standing and layering, so the subsequent spray drying is not performed.

[0109] Comparative Example 4

[0110] A preparation method of a plant sterol micro-nano powder, comprising the following preparation steps:

[0111] (1) Under the condition of normal temperature and magnetic stirring (speed 1000 rpm, time 30 min), gum arabic is dispersed and dissolved in deionized water according to the mass ratio (1:24) to obtain a gum arabic solution;

[0112] (2) Select n-hexane, anhydrous ethanol and ethyl acetate to configure an organic solvent according to the mass percentage (20%:30%:50%);

[0113] (3) Plant sterols and lecithin are respectively dissolved in the prepared organic solvent (12000 rpm, 4 min) according to the mass ratio (1:7) and (1:21), and are fully dissolved by stirring and ultrasonic oscillation, so as to obtain a plant sterol solution; wherein the magnetic stirring speed is 800 rpm, and the stirring time is 5 min;

[0114] (4) The plant sterol solution is added to the gum arabic solution according to the mass ratio (1:4), and a mixed emulsion is obtained by high-speed shearing.

[0115] Test:

[0116] The mixed emulsion cannot form a uniform emulsion after standing and layering, so the subsequent spray drying is not performed.

[0117] in conclusion:

[0118] Comparative Examples 1-5 Figures 1-5 It can be seen that the phytosterol micro-nano powder prepared in Example 5 contains up to 70% phytosterol and has an encapsulation rate of up to 88.24%. The emulsion in Example 5 has a minimum particle size of 476.17±174.52 nm, a minimum PDI of 0.47±0.13, and a maximum absolute potential of 42.13±2.54 mV, indicating that the system is in the most stable state.

[0119] The phytosterol micro / nano-sized powders obtained in Examples 1-5 were subjected to reconstitution experiments and their particle sizes were measured. The measured particle sizes were 870.64±121.14 nm, 901.12±112.37 nm, 881.47±104.25 nm, 541.75±135.15 nm, and 505.78±87.15 nm, respectively. When the emulsion particle size was less than 1 micrometer, a homogeneous emulsion could be obtained. The emulsion was most stable when the particle size range was 400–500 nm. The emulsion exhibited the best reconstitution properties and stability after spray drying into powder when the emulsion particle size range was 400–500 nm. The particle size after reconstitution was positively correlated with the emulsion particle size.

[0120] Example 5 is readily soluble in water. Compared with commercially available products, after being poured into an aqueous solution, the commercially available product failed to diffuse, while the Example 5 product slowly dissolved in the water. After three gentle shakes, Example 5 dispersed in the water, while the commercially available product showed only slight changes. Shaking and allowing it to stand revealed that the 70% sterol powder of Example 5 readily dissolved in water and was evenly distributed, while the commercially available product could not be evenly distributed and formed noticeable particles in the system. The maximum water saturation of Example 5 was 0.05 g / mL.

[0121] The above data shows that the phytosterol micro-nano powder of the present invention can effectively improve the water solubility of phytosterols, and the phytosterol powder produced can be uniformly distributed in the aqueous phase. The method has the prospect of industrial production and greatly expands the utilization rate of phytosterols.

[0122] Finally, it should be emphasized that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a phytosterol micro- or nano-sized powder having a high concentration and being uniformly distributed in an aqueous phase, characterized in that, The preparation method comprises the following steps: (1) stirring for 30 min under the condition of room temperature and magnetic stirring speed of 1000 rpm, dispersing and dissolving whey protein isolate in deionized water at a mass ratio of 1:99 to obtain an aqueous solution; (2) preparing an organic solvent by mixing n-hexane, anhydrous ethanol and ethyl acetate at a mass percentage ratio of 20:30:50; (3) dissolving phytosterol and lecithin in the prepared organic solvent at a mass ratio of 1:7.3 and 1:34.3 respectively, fully dissolving them by magnetic stirring and ultrasonic oscillation, and obtaining a phytosterol solution; wherein the magnetic stirring speed is 800 rpm, and the stirring time is 5 min; (4) adding the phytosterol solution to the aqueous solution at a mass ratio of 1:3.2, then shearing at a high speed for 4 min at 12000 rpm to obtain a mixed emulsion; (5) removing the organic solvent from the obtained mixed emulsion by rotary evaporation, wherein the rotary evaporation temperature is 45 DEG C, the rotation speed is 60 rpm, the inlet temperature is 160 DEG C, and the outlet temperature is 80 DEG C, to obtain a phytosterol micro-nano powder.

2. A method for preparing a phytosterol micro- or nano-sized powder having a high concentration and being uniformly distributed in an aqueous phase, characterized in that, The preparation method comprises the following steps: (1) stirring for 30 min under the condition of room temperature and magnetic stirring speed of 1000 rpm, dispersing and dissolving whey protein isolate in deionized water at a mass ratio of 1:99 to obtain an aqueous solution; (2) preparing an organic solvent by mixing n-hexane, anhydrous ethanol and ethyl acetate at a mass percentage ratio of 20:30:50; (3) dissolving phytosterol and lecithin in the prepared organic solvent at a mass ratio of 1:7 and 1:21 respectively, fully dissolving them by magnetic stirring and ultrasonic oscillation, and obtaining a phytosterol solution; wherein the magnetic stirring speed is 800 rpm, and the stirring time is 5 min; (4) adding the phytosterol solution to the aqueous solution at a mass ratio of 1:4, then shearing at a high speed for 4 min at 12000 rpm to obtain a mixed emulsion; (5) removing the organic solvent from the obtained mixed emulsion by rotary evaporation, wherein the rotary evaporation temperature is 45 DEG C, the rotation speed is 60 rpm, the inlet temperature is 160 DEG C, and the outlet temperature is 80 DEG C, to obtain a phytosterol micro-nano powder.

3. A high-concentration phytosterol micro-nano powder uniformly distributed in an aqueous phase, which is prepared by the preparation method of claim 1 or 2.

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