A plant sterol ester microcapsule and its preparation method and application and solid beverage

Abstract

The present invention provides a plant sterol ester microcapsule and a preparation method and application thereof and a solid beverage. The method comprises the following steps: preparing an emulsifier solution, adding the plant sterol ester to the emulsifier solution, stirring, shearing, and high-pressure homogenization to obtain an intermediate emulsion of the plant sterol ester; preparing a stabilizer solution, mixing the stabilizer solution with the intermediate emulsion of the plant sterol ester, adding an acidity regulator to adjust the pH, stirring, and shearing to obtain a plant sterol ester emulsion; and drying the plant sterol ester emulsion to obtain a water-dispersible plant sterol ester microcapsule. The water-dispersible plant sterol ester microcapsule prepared by the method of the present invention has a large load, a high encapsulation rate, and good storage stability, and can be applied to the fields of food, cosmetics, medicine, and feed, especially to solid beverages, and has the advantages of good instant solubility, good dispersibility, and not easy to agglomerate.

Description

Technical Field

[0001] The invention belongs to the technical field of food, cosmetics, medicine and feed, and specifically relates to a plant sterol ester microcapsule, a preparation method and application thereof, and a solid beverage. Background Art

[0002] The "China Cardiovascular Health and Disease Report 2020" pointed out that cardiovascular disease deaths accounted for the first place in the total cause of death among urban and rural residents, 46.66% in rural areas and 43.81% in cities. Studies have shown that high blood lipids and high cholesterol are the main risk factors for cardiovascular disease. Although drugs such as statins, ezetimibe, and cholestyramine can lower plasma cholesterol, long-term use of these drugs often shows obvious side effects. In contrast, appropriate dietary intervention can effectively prevent the occurrence of cardiovascular disease and avoid the shortcomings of drug treatment.

[0003] Phytosterol esters are a class of natural active ingredients that exist naturally in foods such as grains, oils, cereals, beans, fruits and vegetables, edible fungi, and seaweed. The U.S. FDA has listed phytosterol esters as generally recognized as safe (GRAS); my country's National Health and Family Planning Commission (now renamed the National Health Commission) has approved phytosterol esters (2010) as new resource foods (now renamed new food ingredients). Studies have shown that phytosterol esters have good cholesterol-lowering, blood lipid-lowering, anti-oxidation, anti-cancer, anti-inflammatory and other biological activities, and have no toxic side effects, so they are known as the "key to life." Therefore, a series of foods can be developed using phytosterol esters as active ingredients.

[0004] However, the structure of phytosterols is composed of three six-membered rings, one five-membered ring and a hydrophobic side chain. These unique chemical structures determine its water-insoluble and poor oil-soluble characteristics, which greatly limits its application in the food, medicine, cosmetics and feed industries. In particular, solid beverages are favored by consumers because of their diverse varieties, unique flavor and easy storage. There are few solid beverages rich in phytosterol esters on the market. Usually, different food components can be directly compounded in a certain proportion to prepare solid beverages. However, phytosterol esters are semi-solid, insoluble in water, and have poor dispersibility. When directly applied to solid beverages, they will have poor solubility, caking, and inability to disperse, which seriously affects the quality of solid beverage products. Therefore, how to provide a phytosterol ester microcapsule that can be directly applied to solid beverage foods is a problem that needs to be solved urgently.

[0005] Although the existing technology can improve the dispersibility of plant sterol esters in water to a certain extent, it has the disadvantages of low loading capacity, poor storage stability, the need to introduce additional organic solvents, and cannot be directly applied to solid beverages. If the loading capacity and stability are to be improved, a lot of emulsifiers and stabilizers need to be added. Therefore, it is necessary to conduct further research to solve the above technical problems. Summary of the invention

[0006] In view of the above technical problems, the present invention provides a method for preparing phytosterol ester microcapsules to improve the dispersibility, loading capacity and stability of phytosterol esters in water.

[0007] The present invention also provides a water-dispersible plant sterol ester microcapsule prepared by the above method, which has the advantages of large loading capacity (>80%), high encapsulation rate (95%), good storage stability, etc., and can be directly applied to solid beverages.

[0008] The present invention also provides an application of the water-dispersible plant sterol ester microcapsule in the preparation of food, cosmetics, medicine and feed, especially in solid beverages, which has the advantages of good instant solubility, good dispersibility and not easy to agglomerate.

[0009] The present invention also provides a solid beverage, comprising the phytosterol ester microcapsules prepared by the preparation method of the phytosterol ester microcapsules, which has the advantages of good instant solubility, good dispersibility and not easy to agglomerate.

[0010] The auxiliary materials used in the present invention are all food-grade emulsifiers (proteins) and stabilizers (polysaccharides), which are of a single type, small amount and high safety. The two form a dense interface film on the outer layer of the plant sterol ester and have good stability.

[0011] The present invention achieves the above technical objectives through the following technical means.

[0012] A method for preparing phytosterol ester microcapsules comprises the following steps:

[0013] Step S1, preparing an emulsifier solution, wherein the emulsifier is soy protein isolate, gelatin or whey protein isolate, adding phytosterol ester to the emulsifier solution, stirring, shearing and high-pressure homogenization to obtain an intermediate emulsion of phytosterol ester, wherein the concentration of the emulsifier solution is 1 to 5% by mass volume; and the mass ratio of the emulsifier solution to the phytosterol ester is 70:30 to 95:5;

[0014] Step S2, preparing a stabilizer solution, wherein the stabilizer is sodium carboxymethyl cellulose, xanthan gum, high methoxy pectin, sodium alginate or carrageenan, mixing the stabilizer solution with the intermediate emulsion of phytosterol ester obtained in step S1, adding an acidity regulator to adjust the pH to 2-4, stirring and shearing to obtain a phytosterol ester emulsion, wherein the concentration of the stabilizer solution is 0.5-3% by mass volume; and the mass ratio of the stabilizer solution to the intermediate emulsion is 1:3-3:1;

[0015] Step S3, drying the phytosterol ester emulsion to obtain water-dispersible phytosterol ester microcapsules.

[0016] In the above scheme, the shearing condition is 5000-20000 rpm, and the shearing time is 1-4 min.

[0017] In the above scheme, the high-pressure homogenization pressure is 20 to 50 MPa, and the homogenization times are 2 to 4 times.

[0018] In the above scheme, the drying method is spray drying or freeze drying.

[0019] In the above scheme, the acidity regulator is hydrochloric acid, citric acid, malic acid, acetic acid or propionic acid.

[0020] A phytosterol ester microcapsule, prepared according to the preparation method of the phytosterol ester microcapsule;

[0021] The phytosterol ester microcapsules include phytosterol esters, emulsifiers, stabilizers and acidity regulators;

[0022] The emulsifier is soy protein isolate, gelatin or whey protein isolate, the emulsifier is prepared into a solution, the mass concentration of the emulsifier solution is 1-5%, and the mass ratio of the emulsifier solution to the plant sterol ester is 70:30-95:5;

[0023] The plant sterol ester is added to the emulsifier solution, and the plant sterol ester intermediate emulsion can be obtained through stirring, shearing and high-pressure homogenization;

[0024] The stabilizer is sodium carboxymethyl cellulose, xanthan gum, high methoxy pectin, sodium alginate or carrageenan, and the stabilizer is prepared into a stabilizer solution, the mass concentration of the stabilizer solution is 0.5-3%, and the mass ratio of the stabilizer solution to the intermediate emulsion is 1:3-3:1;

[0025] The acidity regulator is used to adjust the pH after the stabilizer solution and the intermediate emulsion are mixed, and the pH range is 2-4.

[0026] An application of phytosterol ester microcapsules, wherein the phytosterol ester microcapsules are prepared according to the above preparation method, and the phytosterol ester microcapsules are used in the preparation of food, cosmetics, medicine and feed.

[0027] In the above scheme, the plant sterol ester microcapsules are used in solid beverages.

[0028] A solid beverage comprises the phytosterol ester microcapsules prepared by the preparation method of the phytosterol ester microcapsules.

[0029] In the above scheme, the solid beverage comprises the following components by weight: 5 to 6 parts of plant sterol ester microcapsules, 93.8 to 94.8 parts of beverage powder and 0.2 parts of antioxidant.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. The method of the present invention uses soy protein isolate, gelatin or whey protein isolate as an emulsifier, and sodium carboxymethyl cellulose, xanthan gum, high methoxy pectin, sodium alginate or carrageenan as a stabilizer, with a small amount of use and high safety. Based on the differences in their chemical structures and the charged characteristics under different environments, the plant sterol esters are fully emulsified through self-assembly technology, and freeze-drying or spray-drying is used to prepare water-dispersible plant sterol ester microcapsules with stable structure, large load capacity, high encapsulation rate and good storage stability.

[0032] 2. The present invention selects soy protein isolate, gelatin or whey protein isolate as an emulsifier, the concentration of the emulsifier solution is 1-5% by mass volume, and the mass ratio of the emulsifier solution to the plant sterol ester is 70:30-95:5; sodium carboxymethyl cellulose, xanthan gum, high methoxy pectin, sodium alginate or carrageenan is used as a stabilizer, the concentration of the stabilizer solution is 0.5-3% by mass volume, and the mass ratio of the stabilizer solution to the intermediate emulsion is 1:3-3:1; hydrochloric acid, citric acid, malic acid, acetic acid, propionic acid or sodium hydroxide is used as an acidity regulator, and the pH range is 2-4; the water-dispersible plant sterol ester microcapsules prepared by the above formula have good dispersibility in water, large loading capacity (>80%), high encapsulation rate (95%) and good stability.

[0033] 3. The plant sterol ester microcapsules prepared by the present invention can be directly applied to solid beverages and foods. When directly applied to solid beverages, they have the advantages of good solubility, good dispersibility, and not easy to agglomerate. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The figure is a flow chart for the preparation of plant sterol ester microcapsules.

[0035] Figure 2 The curves of charge of different stabilizers at different pH values ​​and the apparent viscosity of the stabilizer solution changing with shear rate are shown in Figure 2. Figure 2 (A) is the charge of different stabilizers at different pH values. Figure 2 (B) is a graph showing the change in apparent viscosity of different stabilizer solutions with shear rate.

[0036] Figure 3 Laser confocal microscopy images of plant sterol ester emulsions prepared with three different emulsifier-stabilizer combinations. SPI stands for soy protein isolate, CMC-Na stands for sodium carboxymethyl cellulose, WPI stands for whey protein isolate, Car stands for carrageenan, GEL stands for gelatin, and CTS stands for chitosan.

[0037] Figure 4The appearance of three phytosterol ester intermediate emulsions made with emulsifiers only and three phytosterol ester emulsions made with different emulsifier-stabilizer combinations (day 0 and day 5). Among them, SPI stands for soy protein isolate, CMC-Na is sodium carboxymethyl cellulose, GEL is gelatin, CTS is chitosan, WPI is whey protein isolate, and Car is carrageenan.

[0038] Figure 5 Inverted fluorescence micrographs of three phytosterol ester intermediate emulsions made with emulsifiers only and three phytosterol ester emulsions made with different emulsifier-stabilizer combinations (day 0 and day 5). SPI stands for soy protein isolate, CMC-Na stands for sodium carboxymethyl cellulose, GEL stands for gelatin, CTS stands for chitosan, WPI stands for whey protein isolate, and Car stands for carrageenan.

[0039] Figure 6 The viscosity of the phytosterol ester emulsion prepared with whey protein isolate as emulsifier and different stabilizers varies with shear rate, and the viscosity of the water-dispersible phytosterol ester emulsion varies with plate rotation frequency. Figure 6 (A) is the viscosity variation curve of the phytosterol ester emulsion prepared with whey protein isolate as emulsifier and different stabilizers as a function of shear rate; Figure 6 (B) Curves of water-dispersible plant sterol ester emulsions prepared with whey protein isolate as emulsifier and different stabilizers as the plate rotates at different frequencies. In the figure, WPI represents whey protein isolate, Car represents carrageenan, CTS represents chitosan, SA represents sodium alginate, HMP represents high methoxyl pectin, CMC-Na represents sodium carboxymethyl cellulose, and XG represents xanthan gum.

[0040] Figure 7 The storage appearance pictures of plant sterol ester emulsions made of soy protein isolate and different stabilizers. Among them, SPI stands for whey protein isolate, CMC-Na stands for sodium carboxymethyl cellulose, HMP stands for high methoxyl pectin, SA stands for sodium alginate, Car stands for carrageenan, XG stands for xanthan gum, and CTS stands for chitosan. DETAILED DESCRIPTION

[0041] The preferred embodiments of the present invention are described below. It should be understood that the embodiments are for better explanation of the present invention and are not intended to limit the present invention. The experimental methods used in the following embodiments are conventional methods unless otherwise specified; the materials, reagents, etc. used in the following embodiments are all commercially available unless otherwise specified.

[0042] Combination Figure 1 The method for preparing the phytosterol ester microcapsules of the present invention comprises the following steps:

[0043] Step S1, preparing an emulsifier solution, adding the phytosterol ester to the emulsifier solution, and obtaining an intermediate emulsion of the phytosterol ester by stirring, shearing, and high-pressure homogenization;

[0044] Step S2, preparing a stabilizer solution, mixing the stabilizer solution with the intermediate emulsion of phytosterol esters, adding an acidity regulator to adjust the pH, stirring and shearing to obtain a phytosterol ester emulsion;

[0045] Step S3, drying the phytosterol ester emulsion to obtain phytosterol ester microcapsules with good water dispersibility.

[0046] The emulsifier is one of soybean protein isolate, gelatin and whey egg isolate; the mass concentration of the emulsifier solution is 1-5%.

[0047] The mass ratio of the emulsifier solution to the phytosterol is 70:30 to 95:5.

[0048] The shearing condition is 5000-20000 rpm, and the shearing time is 1-4 min.

[0049] The high-pressure homogenization pressure is 20-50 MPa, and the homogenization times are 2-4 times.

[0050] The stabilizer is one of sodium carboxymethyl cellulose, xanthan gum, high methoxy pectin, sodium alginate and carrageenan; the mass concentration of the stabilizer solution is 0.5-3%.

[0051] The mass ratio of the stabilizer solution to the intermediate emulsion is 1:3 to 3:1.

[0052] The acidity regulator is hydrochloric acid, citric acid, malic acid, acetic acid, propionic acid and sodium hydroxide; and the pH range is 2-4.

[0053] The drying method is spray drying or freeze drying.

[0054] A plant sterol ester microcapsule is obtained according to the plant sterol microcapsule preparation method.

[0055] The invention discloses an application of plant sterol ester microcapsules in the preparation of food, cosmetics, medicine and feed, especially in solid beverages.

[0056] Determination of particle size, potential, and PDI: dilute the plant sterol ester emulsion 500 times and place the dilution in an EP tube; use a Litesizer TM 500 laser particle size analyzer was used to measure the particle size, Zeta potential and PDI. The particle size and PDI were measured using a disposable sample cell at a temperature of 25°C, a measuring angle of 175° backscattering, and a sample volume of 1 mL. The Zeta potential was measured using an Ω sample cell II at a temperature of 25°C and a sample volume of 0.7 mL.

[0057] Inverted fluorescence microscopy observation: 1 mL of phytosterol ester emulsion was put into an EP tube, and 10 μL of Nile red was added to stain the phytosterol ester in the emulsion. The staining lasted for 20 min, and then 10 μL was put on a glass slide, covered with a coverslip, and allowed to stand for 15 min. The microstructure was observed using a CTR4000B inverted fluorescence microscope (Leica Instruments, Germany) with an eyepiece of 10× and an objective of 40×.

[0058] Laser confocal microscopy observation: Phytosterol esters can be stained with Nile red to emit green light, stabilizers can be stained with fast green to emit red light, and stabilizers can be stained with fluorescent whitening dye to emit blue light. Prepare 1 mg / mL Nile red, fast green and fluorescent whitening dye solutions respectively, take 1 mL of phytosterol ester emulsion in an EP tube, add 20 μL of Nile red, fast green and fluorescent whitening dye solutions in sequence, and dye the phytosterol ester, emulsifier and stabilizer respectively; after staining for 15 minutes, take 10 μL of phytosterol ester emulsion on a slide, then cover it lightly with a coverslip, let it stand for 15 minutes, and use a Leica TCSSP5 laser confocal microscope (Leica Instrument Co., Ltd., Germany) at excitation wavelengths of 488, 633 and 405 nm, using a 10× eyepiece and a 40× objective lens to observe the distribution of phytosterol esters, emulsifiers and stabilizers.

[0059] The loading rate and encapsulation efficiency of phytosterol esters were calculated according to formula (1) and formula (2), respectively:

[0060] Loading amount (%) = mass of phytosterol esters in sample / total mass of sample × 100 Formula (1)

[0061] Encapsulation rate (%) = (total mass of phytosterol esters in the sample - mass of unencapsulated phytosterol esters) / total mass of phytosterol esters in the sample × 100 Formula (2)

[0062] Screening of emulsifier types:

[0063] Prepare the plant sterol ester intermediate emulsion according to the following 7 conditions respectively

[0064] 1) Prepare a 1% soy protein isolate solution, mix the soy protein isolate solution with phytosterol esters (purchased from Xi'an Haisifu Biotechnology Co., Ltd., LowChol TM -S plant sterol esters) were mixed in a mass ratio of 90:10, sheared for 2 min using a high-speed shearing machine at a speed of 10000 rpm, and then homogenized three times at 30 MPa using an AH-BASIC high-pressure homogenizer (ATS Industries, Ltd.) to obtain a plant sterol ester intermediate emulsion.

[0065] 2) A pea protein solution with a mass concentration of 1% was prepared, and the pea protein solution was mixed with phytosterol ester in a mass ratio of 90:10, sheared at 10000 rpm for 2 min, and then homogenized three times at 30 MPa using an AH-BASIC high-pressure homogenizer (ATS Industries, Ltd.) to obtain a phytosterol ester intermediate emulsion.

[0066] 3) preparing a gelatin solution with a mass concentration of 1%, mixing the gelatin solution with the phytosterol ester in a mass ratio of 90:10, shearing at 10,000 rpm for 2 min, and then homogenizing three times at 30 MPa using an AH-BASIC high-pressure homogenizer (ATS Industries, Ltd.) to obtain a phytosterol ester intermediate emulsion.

[0067] 4) A whey protein solution with a mass concentration of 1% was prepared, and the whey protein solution was mixed with the plant sterol ester in a mass ratio of 90:10, sheared at 10000 rpm for 2 min, and then homogenized three times at 30 MPa using an AH-BASIC high-pressure homogenizer (ATS Industries, Ltd.) to obtain a plant sterol ester intermediate emulsion.

[0068] 5) A whey protein isolate solution with a concentration of 1% was prepared, and the whey protein isolate solution was mixed with the plant sterol ester in a mass ratio of 90:10, sheared at 10000rpm for 2min, and then homogenized 3 times at 30MPa using an AH-BASIC high pressure homogenizer (ATS Industrial Co., Ltd.) to obtain a plant sterol ester intermediate emulsion. The particle size, potential and PDI of the plant sterol ester intermediate emulsion prepared in this example are shown in Table 1.

[0069] Table 1 Particle size, potential and PDI of phytosterol ester intermediate emulsion

[0070]

[0071] Note: Data marked with different letters (a, b, c, d, e) in the same column are significantly different (p<0.05)

[0072] Particle size, particle size distribution index (PDI) and Zeta potential are important characterization methods for emulsions. The smaller the droplet size, the weaker the Brownian motion and the better the stability of the emulsion. The smaller the PDI, the more uniform the distribution of the emulsion droplets, and vice versa. When the absolute value of the Zeta potential is greater than 20mV, it is generally believed that the emulsion has sufficient electrostatic repulsion and is not easy to form large droplets.

[0073] As can be seen from Table 1, among the five emulsifiers, the particle size of soy protein isolate, gelatin, and whey protein isolate groups is relatively small (less than 3000nm), while the particle size of pea protein and whey protein is relatively large. This may be related to their low emulsification activity, and some plant sterol esters cannot be emulsified, resulting in larger particle size. The absolute value of the intermediate emulsion potential is greater than 20mV, and there is sufficient electrostatic repulsion to prevent droplet flocculation, which is conducive to the stability of the emulsion. The PDI of the pea protein and whey protein groups is greater than 30%, and the droplet distribution is uneven. This may be due to the weak emulsification of the two proteins, and the plant sterol esters are not completely and evenly dispersed. At the same time, droplets of different sizes appear, resulting in an increase in PDI. Based on the comprehensive particle size, absolute value of potential and PDI data, soy protein isolate, gelatin and whey protein isolate were selected as emulsifiers for the subsequent preparation of water-dispersible plant sterol esters.

[0074] Screening of stabilizer types:

[0075] Prepare stabilizer solutions according to the following 7 conditions respectively and screen the appropriate stabilizer types.

[0076] 1) Prepare a 0.5% sodium carboxymethyl cellulose solution. Using a DHR-1 rheometer (Waters, USA), select a 40 mm plate, set the temperature at 25°C, take 1.3 mL of sodium carboxymethyl cellulose solution and drop it on the lower plate, the shear rate is 0.1-100 rad / s, and measure the apparent viscosity of the sodium carboxymethyl cellulose solution at different shear rates; then dilute it 50 times to obtain a 0.01% sodium carboxymethyl cellulose solution, adjust its pH to 2-8 using 1M HCl and 1M NaOH, and measure the Zeta potential of the sodium carboxymethyl cellulose solution at different pH values.

[0077] 2) Prepare a xanthan gum solution with a mass concentration of 0.5%. Using a DHR-1 rheometer (Waters, USA), select a 40 mm plate, the temperature is 25°C, take 1.3 mL of xanthan gum solution and drop it on the lower plate, the shear rate is 0.1-100 rad / s, and the apparent viscosity of the 1% xanthan gum solution at different shear rates is measured; dilute it 50 times to obtain a xanthan gum solution with a concentration of 0.01%, use 1M HCl and 1M NaOH to adjust its pH to 2-8, and measure the Zeta potential of the xanthan gum solution at different pH.

[0078] 3) Prepare a 0.5% high methoxy pectin solution. Use a DHR-1 rheometer (Waters, USA), select a 40 mm plate, set the temperature at 25°C, take 1.3 mL of the high methoxy pectin solution and drop it on the lower plate, the shear rate is 0.1-100 rad / s, and measure the apparent viscosity of the 0.5% high methoxy pectin solution at different shear rates; dilute it 50 times to obtain a 0.01% high methoxy pectin solution, adjust its pH to 2-8 using 1M HCl and 1M NaOH, and measure the Zeta potential of the high methoxy pectin solution at different pH values.

[0079] 4) Prepare a sodium alginate solution with a mass concentration of 0.5%. Use a DHR-1 rheometer (Waters, USA), select a 40 mm plate, set the temperature at 25°C, take 1.3 mL of sodium alginate solution and drop it on the lower plate, the shear rate is 0.1-100 rad / s, and measure the apparent viscosity of the 1% sodium alginate solution at different shear rates; dilute it 50 times to obtain a sodium alginate solution with a concentration of 0.01%, adjust its pH to 2-8 using 1M HCl and 1M NaOH, and measure the Zeta potential of the sodium alginate solution at different pH values.

[0080] 5) Prepare a carrageenan solution with a mass concentration of 0.5%. Use a DHR-1 rheometer (Waters, USA), select a 40 mm plate, set the temperature at 25°C, take 1.3 mL of carrageenan solution and drop it on the lower plate, the shear rate is 0.1-100 rad / s, and measure the apparent viscosity of the 1% carrageenan solution at different shear rates; dilute it 50 times to obtain a carrageenan solution with a concentration of 0.01%, adjust its pH to 2-8 using 1M HCl and 1M NaOH, and measure the Zeta potential of the carrageenan solution at different pH values.

[0081] 6) Prepare a 0.5% gum arabic solution. Use a DHR-1 rheometer (Waters, USA) with a 40 mm plate at 25°C, drop 1.3 mL of gum arabic solution onto the lower plate, and measure the apparent viscosity of the 1% gum arabic solution at different shear rates at a shear rate of 0.1 to 100 rad / s; dilute it 50 times to obtain a 0.01% gum arabic solution, adjust its pH to 2 to 8 using 1 M HCl and 1 M NaOH, and measure the Zeta potential of the gum arabic solution at different pH values.

[0082] 7) Prepare chitosan solution with a mass concentration of 0.5%. Use DHR-1 rheometer (Waters, USA), select 40mm plate, temperature at 25°C, take 1.3mL chitosan solution and drop it on the lower plate, the shear rate is 0.1-100rad / s, and measure the apparent viscosity of 1% chitosan solution at different shear rates; then dilute it 50 times to obtain a chitosan solution with a concentration of 0.01%, adjust its pH to 2-8 using 1MHCl and 1MNaOH, and measure the Zeta potential of chitosan solution at different pH.

[0083] Different stabilizers have different charges (electric potentials of different positive and negative magnitudes) at different pH. Figure 2 (A) shows the charge of 7 different stabilizers at different pH values. As shown in the figure, chitosan is a cationic polysaccharide, which is positively charged in the entire pH range and can interact electrostatically with negatively charged proteins in the pH range of 2 to 8. The other 6 stabilizers are all anionic polysaccharides, which are negatively charged in the entire pH range and can interact electrostatically with positively charged proteins. In addition, polysaccharides have hydrophilic segments that can bind a large amount of water, thereby increasing the viscosity of the continuous water phase to maintain the stability of the emulsion system. Figure 2 (B) is a graph showing the change in apparent viscosity of seven different stabilizers as the shear rate increases. As can be seen from the figure, as the shear rate increases, the viscosity gradually decreases, showing a shear thinning phenomenon. When the shear rate is 0.1rad / s, the viscosity of sodium carboxymethyl cellulose is the highest at about 0.4Pa·s, followed by xanthan gum, sodium alginate and carrageenan with an initial viscosity of 0.2Pa·s, and gum arabic has the lowest viscosity. Gum arabic has the property of having a low viscosity at high concentrations and a low charge. Based on the above reasons, sodium carboxymethyl cellulose, sodium alginate, carrageenan, xanthan gum and high methoxy pectin were selected as stabilizers for the subsequent preparation of plant sterol ester emulsions.

[0084] Physical and chemical properties and structure:

[0085] (1) Prepare a 1% soy protein isolate solution and a 0.5% sodium carboxymethyl cellulose solution, mix the soy protein isolate solution with phytosterol esters (purchased from Xi'an Haisifu Biotechnology Co., Ltd., LowChol TM -S plant sterol ester) were mixed at a mass ratio of 95:5, sheared at 5000rpm for 1min, and homogenized 4 times at 20MPa to obtain an intermediate emulsion; sodium carboxymethyl cellulose solution was mixed with the intermediate emulsion at a mass ratio of 1:3, the pH was adjusted to 4 with 1M citric acid, and sheared at 5000rpm for 1min to obtain a plant sterol ester emulsion. The particle size, potential and PDI of the intermediate emulsion and plant sterol ester emulsion were measured, microscopic images were taken using an inverted fluorescence microscope, and the distribution of plant sterol esters, soy protein isolate and sodium carboxymethyl cellulose was observed using laser confocal microscopy.

[0086] Table 2 Particle size, potential and PDI of phytosterol ester emulsion

[0087]

[0088] Note: Data marked with different letters (a, b) in the same column are significantly different (p<0.05); SPI: soy protein isolate; CMC-Na: sodium carboxymethyl cellulose

[0089] As shown in Table 2, the particle size of the intermediate emulsion of phytosterol esters prepared by using soy protein isolate as an emulsifier is 2466nm, the absolute value of the potential is greater than 30mV, there is sufficient electrostatic repulsion, and the PDI is small. After adding the stabilizer, the particle size of the emulsion increases by 40%, which is because the stabilizer is adsorbed on the surface of the emulsifier, the thickness of the interface film increases, and the particle size increases. Figure 3 The laser confocal results show that phytosterol esters are dyed green by Nile red, soy protein isolate is dyed red by Fast Green, and sodium carboxymethyl cellulose is dyed blue by fluorescent whitening dye. Soy protein isolate and sodium carboxymethyl cellulose are both hollow spheres, and the emulsions are phytosterol esters, soy protein isolate and sodium carboxymethyl cellulose from the inside to the outside, indicating that the wall material is successfully wrapped on the surface of phytosterol esters. Figure 4 Appearance image and Figure 5 From the microscopic images, it can be seen that the intermediate emulsion made with only soy protein isolate as an emulsifier and the emulsion made with carboxymethyl cellulose as a stabilizer had uniform droplet distribution on the 0th day, and no instability occurred. After 5 days of storage, the droplets of the intermediate emulsion flocculated significantly, and an emulsified layer was formed above the emulsion, while the emulsion with the stabilizer had good stability. This is because the intermediate emulsion stabilized only by soy protein isolate has a low viscosity, the Brownian motion between droplets is fast, and the interfacial film is thin, which is very easy to flocculate and demulsify, and has poor stability. Although the particle size of the emulsion stabilized by the emulsifier and stabilizer increases, the droplet interfacial film is thicker, it is not easy to demulsify, the droplet fluidity is reduced, and the stability is good.

[0090] (2) preparing a whey protein isolate solution with a mass concentration of 5% and a carrageenan solution with a mass concentration of 3%; mixing the whey protein isolate solution with plant sterol esters (purchased from Xi'an Haisifu Biotechnology Co., Ltd., LowChol TM-S plant sterol ester) were mixed at a mass ratio of 70:30, sheared at 20000rpm for 4min, and homogenized twice at 50MPa to obtain an intermediate emulsion; the carrageenan solution and the intermediate emulsion were mixed at a mass ratio of 3:1, the pH was adjusted to 3 with citric acid, and sheared at 20000rpm for 4min to obtain a plant sterol ester emulsion. The particle size, potential, and PDI of the intermediate emulsion and the plant sterol ester emulsion were measured; microscopic images were taken using inverted fluorescence, and the distribution of plant sterol esters, whey protein isolate, and carrageenan was observed by laser confocal microscopy; the intermediate emulsion and plant sterol ester emulsion were respectively divided into two 15mL glass vials, and their appearance changes were observed, and appearance images were taken at regular intervals.

[0091] Table 3 Particle size, potential and PDI of phytosterol ester emulsion

[0092]

[0093] Note: Data marked with different letters (a, b) in the same column are significantly different (p<0.05); WPI: whey protein isolate; Car: carrageenan

[0094] As shown in Table 3, the particle size of the plant sterol ester intermediate emulsion prepared with whey protein isolate as an emulsifier is 2562nm, the absolute value of the potential is greater than 30mV, there is sufficient electrostatic repulsion, and the PDI is small. After adding the stabilizer, the solution particle size increased by 41%, which is because the stabilizer is adsorbed on the surface of the emulsifier, the thickness of the interface film increases, and the particle size increases. Figure 3 The laser confocal microscope results show that phytosterol esters are dyed green by Nile red, whey protein isolate is dyed red by Fast Green, and carrageenan is dyed blue by fluorescent whitening dye. Both whey protein isolate and carrageenan are hollow spheres. The droplets are phytosterol esters, whey protein isolate and carrageenan from the inside to the outside, respectively. The wall material is successfully wrapped on the surface of phytosterol esters. Figure 4 Appearance image and Figure 5 From the microscopic images, we can see that the intermediate emulsion made with whey protein isolate as emulsifier and the solution made with carrageenan as stabilizer had uniform droplet distribution on the 0th day, and no instability occurred. However, after 5 days of storage, the intermediate emulsion droplets flocculated significantly, forming an emulsified layer above the solution, and the emulsion with stabilizer had good stability. This is because the intermediate emulsion stabilized by whey protein isolate has a lower viscosity, faster Brownian motion between droplets, and a thin interface film, which is prone to flocculation and demulsification, and poor stability; although the particle size of the emulsion stabilized by emulsifier and stabilizer increases, the droplet interface film is thicker, not easy to demulsify, the droplet fluidity is reduced, and the stability is good.

[0095] (3) Prepare a gelatin solution with a mass concentration of 2.5% and a chitosan solution with a mass concentration of 2%; mix the gelatin solution with plant sterol esters (purchased from Xi'an Haisifu Biotechnology Co., Ltd., LowChol TM -S plant sterol ester) were mixed at a mass ratio of 85:15, sheared at 10000rpm for 2min, and homogenized at 30MPa for 3 times to obtain an intermediate emulsion; chitosan solution and intermediate emulsion were mixed at a mass ratio of 2:1, the pH was adjusted to 2 with hydrochloric acid, and sheared at 10000rpm for 2min to obtain a plant sterol ester emulsion. The particle size, potential, and PDI of the intermediate emulsion and plant sterol ester emulsion were measured; microscopic images were taken using inverted fluorescence; and the distribution of plant sterol esters, gelatin, and chitosan was observed using laser confocal microscopy.

[0096] Table 4 Particle size, potential and PDI of phytosterol ester emulsion

[0097]

[0098] Note: Data marked with different letters (a, b) in the same column are significantly different (p<0.05); GEL: gelatin; CTS: chitosan

[0099] As shown in Table 4, the particle size of the intermediate emulsion of plant sterol esters prepared with gelatin as an emulsifier is 2384nm, the absolute value of the potential is greater than 20mV, and the PDI is small. After adding the stabilizer, the particle size of the emulsion increased by 49%. This is because the stabilizer is adsorbed on the surface of the emulsifier, the thickness of the interface film increases, and the particle size increases. Chitosan is a cationic stabilizer, so the prepared emulsion is positively charged. Figure 3 Laser confocal microscopy results show that phytosterol esters are dyed green by Nile red, gelatin is dyed red by Fast Green, and chitosan is dyed blue by fluorescent whitening dye. Both gelatin and chitosan are hollow spheres. The droplets are phytosterol esters, gelatin, and chitosan from the inside to the outside, respectively. The wall material is successfully wrapped on the surface of phytosterol esters. Figure 4 Appearance image and Figure 5 From the microscopic images, it can be seen that the intermediate emulsion made with gelatin as an emulsifier and the emulsion made with chitosan as a stabilizer had uniform droplet distribution on day 0, and no instability occurred. After 5 days of storage, the droplets of the intermediate emulsion flocculated significantly, and an emulsified layer was formed above the emulsion, while the emulsion with stabilizer had good stability. This is because the intermediate emulsion stabilized by gelatin alone has a lower viscosity, faster Brownian motion between droplets, and a thin interface film, which is very easy to flocculate and demulsify, and has poor stability. Although the particle size of the emulsion stabilized by the emulsifier and stabilizer increases, the droplet interface film is thicker, not easy to demulsify, the droplet fluidity is reduced, and the stability is good.

[0100] In summary, although the phytosterol emulsion stabilized only by emulsifiers has a large particle size and strong fluidity, the interfacial film formed is thin and very easy to flocculate, aggregate, and demulsify, and the prepared phytosterol emulsion has poor storage stability. After adding stabilizers, although the emulsion particle size increases, the interfacial film thickness increases, the fluidity decreases, and the stability is better.

[0101] Rheological properties:

[0102] A 1% soy protein isolate solution was mixed with plant sterol esters (purchased from Xi'an Haisifu Biotechnology Co., Ltd., LowChol TM -S plant sterol ester) was mixed at a mass ratio of 90:10, sheared for 2 minutes using a high-speed shearing machine at a speed of 10000rpm, and then homogenized twice at 40MPa using an AH-BASIC high-pressure homogenizer (ATS Industrial Co., Ltd.) to obtain a plant sterol ester intermediate emulsion. Carrageenan, chitosan, sodium alginate, high methoxy pectin, sodium carboxymethyl cellulose and xanthan gum solution with a mass concentration of 2% were mixed with the intermediate emulsion at a mass ratio of 2:1, and the pH was adjusted using NaOH and malic acid. The pH of the chitosan group was 7, and the pH of the others was 4. The emulsion was homogenized at 15000rpm for 2 minutes to obtain a water-dispersible plant sterol ester emulsion.

[0103] Using a DHR-1 rheometer (Waters, USA), a 40 mm plate was selected and the temperature was 25°C. 1.3 mL of the phytosterol ester emulsion prepared in the above steps was dropped onto the lower plate at a shear rate of 0.1 to 100 rad / s to measure the static shear rheological properties of the phytosterol ester emulsion. The strain value was set to 1%, the plate rotation frequency was 0.1 to 10 Hz, and the elastic modulus (G') and loss modulus (G") were measured.

[0104] Rheological properties are an important property of emulsions. The higher the viscosity of the emulsion, the less likely the droplets will settle or float, and the more stable it is. Figure 6 (A) It can be seen that the viscosity of all emulsions decreases with increasing shear rate. They are shear-thinning fluids with an apparent viscosity of 50-100S -1 It is almost unchanged within the shear rate range, showing ideal fluid properties. The storage modulus (G') represents the elastic behavior of the emulsion, which is the energy that can be recovered in each shear deformation cycle; the loss modulus (G") represents the viscous behavior of the emulsion, which is the energy consumed in each shear behavior. A dynamic frequency sweep test is performed within the linear viscoelastic range to determine the frequency dependence of the storage modulus and loss modulus. According to Figure 6 (B) The results show that for the plant sterol ester emulsion, G' and G" increase with increasing frequency over the entire frequency range, indicating that the emulsion forms a gel network structure dominated by elasticity.

[0105] Storage stability:

[0106] A 2% soy protein isolate solution was prepared, and 1% sodium carboxymethyl cellulose, xanthan gum, high methoxy pectin, sodium alginate, carrageenan, and chitosan solutions were prepared. The soy protein isolate solution was mixed with plant sterol esters (purchased from Xi'an Haisifu Biotechnology Co., Ltd., LowChol TM -S plant sterol ester) was mixed at a mass ratio of 80:20, sheared at 20000rpm for 2min, and homogenized 3 times at 30MPa to obtain an intermediate emulsion; the stabilizer solution and the intermediate emulsion were mixed at a mass ratio of 1:1, and the pH was adjusted using 1MNaOH and 1M acetic acid. The pH of the chitosan group emulsion was adjusted to 8, and the rest were 3. Sheared at 10000rpm for 2min to obtain a plant sterol ester emulsion. The plant sterol ester emulsions prepared with soy protein isolate and different stabilizers were divided into 15mL glass vials, 2 vials per group, and placed in a 25℃ constant temperature box. The appearance pictures were observed at 0, 14, 28, 42, 56, and 70d, respectively.

[0107] Depend on Figure 7 It is known that among the plant sterol ester emulsions made from soy protein isolate and different stabilizers, the emulsions stabilized by sodium carboxymethyl cellulose, high methoxy pectin, and sodium alginate were stored for 70 days without significant changes in appearance. This is related to the high viscosity of the three emulsions, poor droplet fluidity, and thus difficulty in flocculation and agglomeration. The carrageenan and xanthan gum groups were stored for 42 days, and there was a slight emulsification phenomenon in the upper layer, which may be related to the lower charge of the emulsion than the previous three groups and the smaller electrostatic repulsion. The plant sterol ester emulsion stabilized by chitosan has poor stability, which may be related to the low charge of its emulsion and the lack of sufficient electrostatic repulsion to prevent droplet flocculation. In summary, the plant sterol ester emulsion has good storage stability.

[0108] Embodiment 1:

[0109] A whey protein isolate solution with a mass concentration of 1.5% was prepared, and at the same time, sodium carboxymethyl cellulose, xanthan gum, high methoxy pectin, sodium alginate, carrageenan, and chitosan solutions with a mass concentration of 0.5% were prepared. The whey protein isolate solution was mixed with plant sterol esters (purchased from Xi'an Haisifu Biotechnology Co., Ltd., LowChol TM -S plant sterol ester) were mixed at a mass ratio of 85:15, sheared at 15000rpm for 2min, and homogenized 3 times at 40MPa to obtain an intermediate emulsion; the stabilizer solution and the intermediate emulsion were mixed at a mass ratio of 2:1, and the pH was adjusted using 1MNaOH and 1M propionic acid. Among them, the pH of the chitosan group emulsion was adjusted to 8, and the others were all 3. Sheared at 15000rpm for 2min to obtain five plant sterol ester emulsions with different emulsifiers and stabilizers.

[0110] A gelatin solution with a mass concentration of 1.5% was prepared, and at the same time, sodium carboxymethyl cellulose, xanthan gum, high methoxy pectin, sodium alginate, carrageenan, and chitosan solutions with a mass concentration of 0.5% were prepared respectively. The gelatin solution and the plant sterol ester were mixed in a mass ratio of 90:10, sheared at 15000rpm for 2min, and homogenized 3 times at 40MPa to obtain an intermediate emulsion; the stabilizer solution and the intermediate emulsion were mixed in a mass ratio of 2:1, and the pH was adjusted using 1MNaOH and 1MHCl. Among them, the pH of the chitosan group emulsion was adjusted to 8, and the rest were 3.5. Sheared at 15000rpm for 2min to obtain five different combinations of plant sterol ester emulsions. Subsequently, the prepared plant sterol ester emulsion and the intermediate emulsion were spray-dried using a Ymnl-015P spray dryer (Nanjing Emmanuel Instrument Equipment Co., Ltd.), and finally water-dispersible plant sterol ester microcapsules with uniform particles were obtained ( Figure 1 Microcapsules A). Spray drying parameters are as follows: inlet air temperature 180°C, outlet air temperature 90°C, average feed rate 7 mL / min.

[0111] Accurately weigh 20g of phytosterol ester emulsion and the corresponding intermediate emulsion, add 20mL petroleum ether (boiling point 60-90°C), stir at 100rpm for 5min; then place the petroleum ether and emulsion mixture in a 50ml centrifuge tube and centrifuge at 5000rpm for 10min. Take 10mL of the upper petroleum ether solution after centrifugation in a round-bottomed biscuit, rotary evaporate at 40°C, and keep constant weight in a 120°C oven, record the mass of the collected phytosterol ester (i.e. the mass of the unencapsulated phytosterol ester), and calculate the loading amount and encapsulation rate of the phytosterol ester in the water-dispersible phytosterol ester emulsion and the corresponding intermediate emulsion.

[0112] Accurately weigh 10g of the phytosterol ester microcapsules obtained by spray drying, add 100mL of petroleum ether (boiling point 60-90°C), stir at 100rpm for 2 minutes; filter, collect petroleum ether (boiling point 60-90°C) and insoluble matter respectively, and the collected insoluble matter is treated twice in the same way. Mix the petroleum ether (boiling point 60-90°C) layers collected three times, rotary evaporate at 40°C, and keep constant weight in an oven at 120°C, record the mass of the collected phytosterol ester (i.e., the mass of the unencapsulated phytosterol ester), and calculate the loading amount and encapsulation rate of the phytosterol ester in the water-dispersible phytosterol ester microcapsules obtained by spray drying.

[0113] Weigh 20g of the spray-dried plant sterol ester microcapsule product and place it in a 50mL vial, which is then placed in a 25°C constant temperature incubator for storage. The peroxide values ​​of these microcapsule samples were measured according to GB5009.227-2016 at 0 and 180 days of storage, and the storage stability was calculated according to formula (3). The results <120% were defined as good storage stability, the results between 120% and 150% were defined as medium storage stability, and the results >150% were defined as poor storage stability. The storage stability results of different microcapsules are shown in Table 5.

[0114] Storage stability (%) = (peroxide value of microcapsules at 180 days - peroxide value of microcapsules at 0 days) / peroxide value of microcapsules at 0 days × 100 Formula (3)

[0115] Table 5 Loading capacity, encapsulation efficiency and storage stability of microcapsules A prepared by water-dispersible phytosterol ester emulsion and spray drying

[0116]

[0117] Note: Data marked with different letters (a, b, c, d) in the same column are significantly different (p<0.05); WPI: whey protein isolate; GEL: gelatin; CMC-Na: sodium carboxymethyl cellulose; Car: carrageenan; SA: sodium alginate; HMP: high methoxyl pectin; CTS: chitosan; XG: xanthan gum

[0118] Table 5 shows the loading and encapsulation efficiency of the water-dispersible phytosterol ester emulsions prepared by whey protein isolate and gelatin as emulsifiers and different stabilizers, and the phytosterol esters in the microcapsules prepared by spray drying. As shown in Table 5, the loading of the intermediate emulsion stabilized by the emulsifier alone can reach 88.1%, and the encapsulation efficiency is greater than 95%. After spray drying, the encapsulation efficiency decreases (all less than 35%). This is because the interface layer of the intermediate emulsion is thin and has poor stability. After spray drying, the interface layer is destroyed, the phytosterol esters are exposed, and the encapsulation efficiency is low. The loading of phytosterol esters in the samples prepared by different emulsifier-stabilizer combinations can reach 81%, and the encapsulation efficiency is greater than 95%. The microcapsules A obtained by spray drying have an encapsulation efficiency greater than 60%. Among them, the highest encapsulation efficiency is greater than 90% when sodium carboxymethyl cellulose is used as a stabilizer. In terms of storage stability, the microcapsules prepared only by WPI or GEI are severely oxidized and have poor storage stability. Microcapsules prepared with WPI-HMP, WPI-CTS, GEL-HMP, and GEL-CTS combinations showed moderate oxidation after 180 days of storage, while the other combinations showed good storage stability. These results indicate that water-dispersible phytosterol ester microcapsules prepared with selected emulsifier-stabilizer combinations have high loading, encapsulation efficiency, and oxidative stability.

[0119] Embodiment 2:

[0120] A whey protein isolate solution with a mass concentration of 1% was prepared, and 0.5% sodium carboxymethyl cellulose, xanthan gum, high methoxy pectin, sodium alginate, carrageenan, and chitosan solutions were prepared respectively. The whey protein isolate solution was then mixed with plant sterol esters (purchased from Xi'an Haisifu Biotechnology Co., Ltd., LowChol TM -S plant sterol ester) in a mass ratio of 90:10, sheared at 10000rpm for 2min, and homogenized 3 times at 30MPa to obtain an intermediate emulsion; mixed with the stabilizer solution and the intermediate emulsion in a mass ratio of 2:1, and adjusted the pH using 1MNaOH and 1MHCl. The pH of the chitosan group emulsion was adjusted to 8, and the pH of the others was 2.5. Sheared at 10000rpm for 2min to obtain five plant sterol ester emulsions with different emulsifier and stabilizer combinations.

[0121] A 1% soy protein isolate solution was prepared, and 1% sodium carboxymethyl cellulose, xanthan gum, high methoxy pectin, sodium alginate, carrageenan, and chitosan solutions were prepared. Then, the soy protein isolate solution was mixed with plant sterol esters (purchased from Xi'an Haisifu Biotechnology Co., Ltd., LowChol TM -S plant sterol ester) were mixed at a mass ratio of 85:15, sheared at 10000rpm for 2min, and homogenized 3 times at 30MPa to obtain an intermediate emulsion; the stabilizer solution and the intermediate emulsion were mixed at a mass ratio of 2:1, and the pH was adjusted using 1MNaOH and 1MHCl. The pH of the chitosan group emulsion was adjusted to 8, and the pH of the others was adjusted to 2.5. Sheared at 10000rpm for 2min to obtain five plant sterol ester emulsions with different emulsifier and stabilizer combinations.

[0122] The freshly prepared phytosterol ester emulsion and the intermediate emulsion were then pre-frozen at -20 °C for 12 h and then freeze-dried in a FD-1A-50 vacuum freezer (Beijing Boyikang Experimental Instrument Co., Ltd.) to obtain water-dispersible phytosterol ester microcapsules ( Figure 1 Microcapsule B). Freeze drying related parameters: temperature is -55°C, pressure is 40MPa, and time is 12h.

[0123] Accurately weigh 20g of phytosterol ester emulsion and the corresponding intermediate emulsion, add 20mL petroleum ether (boiling point 60-90°C), stir at 100rpm for 5 minutes; then place the petroleum ether and emulsion mixture in a 50ml centrifuge tube and centrifuge at 5000rpm for 10min. Take 10mL of the upper petroleum ether solution after centrifugation in a round-bottomed biscuit, rotary evaporate at 40°C, and keep constant weight in a 120°C oven, record the mass of the collected phytosterol ester (i.e. the mass of the unencapsulated phytosterol ester), and calculate the loading amount and encapsulation rate of the water-dispersible phytosterol ester emulsion and the corresponding intermediate emulsion.

[0124] Accurately weigh 10g of the phytosterol ester obtained by freeze drying, add 100mL of petroleum ether (boiling point 60-90°C), stir at 100rpm for 2 minutes; filter, collect petroleum ether (boiling point 60-90°C) and insoluble matter respectively, and the collected insoluble matter is treated twice in the same way. Mix the petroleum ether (boiling point 60-90°C) layers collected three times, rotary evaporate at 40°C, and keep constant weight in a 120°C oven, record the mass of the collected phytosterol ester (i.e., the mass of the unencapsulated phytosterol ester), and calculate the loading amount and encapsulation rate of the phytosterol ester in the water-dispersible phytosterol ester microcapsules obtained by freeze drying.

[0125] Weigh 20g of the freeze-dried plant sterol ester microcapsule product and place it in a 50mL vial, which is then placed in a 25°C constant temperature incubator for storage. The peroxide values ​​of these microcapsule samples were measured according to GB5009.227-2016 at 0 and 180 days of storage, and the storage stability was calculated according to formula (3). The results <120% were defined as good storage stability, the results between 120% and 150% were defined as medium storage stability, and the results >150% were defined as poor storage stability. The storage stability results of different microcapsules are shown in Table 6.

[0126] Table 6 Loading capacity, encapsulation efficiency and storage stability of microcapsules B prepared by water-dispersible phytosterol ester emulsion and freeze-drying

[0127]

[0128] Note: Data marked with different letters (a, b, c, d, e) in the same column are significantly different (p<0.05); WPI: whey protein isolate; SPI: soy protein isolate; CMC-Na: sodium carboxymethyl cellulose; Car: carrageenan; SA: sodium alginate; HMP: high methoxyl pectin; CTS: chitosan; XG: xanthan gum

[0129] Table 6 shows the loading and encapsulation efficiency of the water-dispersible phytosterol ester emulsions prepared by using whey protein isolate and soy protein isolate as emulsifiers and different stabilizers, and the phytosterol esters in the microcapsules obtained by freeze drying. As shown in Table 6, the loading of phytosterol esters in the intermediate emulsion stabilized by emulsifiers alone can reach 91.7%, and the encapsulation efficiency is greater than 95%. After freeze drying, the encapsulation efficiency is low (less than 30%). This is because the interface layer of the intermediate emulsion is thin and has poor stability. The ice crystals in the freeze drying process destroy the interface layer, and some phytosterol esters are exposed, resulting in a low encapsulation efficiency. The loading of the phytosterol ester emulsion prepared by different emulsifier-stabilizer combinations can reach 84%, and the encapsulation efficiency is greater than 95%. The encapsulation efficiency of the microcapsules B obtained by freeze drying the emulsion is greater than 60%. Among them, when sodium carboxymethyl cellulose and carrageenan are used as stabilizers, the encapsulation efficiency is greater than 90%. In terms of storage stability, the microcapsules prepared by WPI or SPI alone are severely oxidized and have poor storage stability. The microcapsules prepared with the combinations of WPI-HMP, WPI-CTS, SPI-HMP, and SPI-CTS showed moderate oxidation after 180 days of storage, while the other combinations showed good storage stability. These results indicate that the water-dispersible phytosterol ester microcapsules prepared with the selected emulsifier-stabilizer combinations have high loading capacity, encapsulation efficiency, and good storage stability.

[0130] Redissolution stability of water-dispersible phytosterol ester microcapsules:

[0131] Take 4g of the water-dispersible plant sterol ester microcapsules prepared by spray drying in Example 1, add 96mL of water, mix evenly, and obtain a reconstituted plant sterol ester emulsion. Take 10.9g of the dried intermediate emulsion, add 89mL of water, mix evenly, and obtain a reconstituted plant sterol ester intermediate emulsion to measure its particle size. At the same time, the reconstituted plant sterol ester emulsion is divided into 15mL glass vials, two vials per group, placed at 25°C, and its appearance picture is observed.

[0132] Table 7 Redissolution stability of phytosterol ester microcapsules A prepared by spray drying

[0133]

[0134] Note: Data marked with different letters (a, b, c, d) in the same column are significantly different (p<0.05) WPI: whey protein isolate; GEL: gelatin; CMC-Na: sodium carboxymethyl cellulose; Car: carrageenan; SA: sodium alginate; HMP: high methoxyl pectin; CTS: chitosan; XG: xanthan gum

[0135] As shown in Table 7, the plant sterol ester intermediate emulsions prepared by spray drying and re-dissolving with whey protein isolate and gelatin as emulsifiers have large particle size and poor stability. Compared with before drying, the particle size increased by 400% to 500% after re-dissolution, and the storage days were less than 15 days. The water-dispersible plant sterol ester microcapsules prepared by whey protein isolate and gelatin as emulsifiers and different stabilizers still have good stability after re-dissolution. Compared with before drying, the particle size increased by about 6% after re-dissolution. The storage days after re-dissolution are all greater than 30 days. The water-dispersible plant sterol ester microcapsules prepared by soy protein isolate and xanthan gum group can be stored for 50 days after re-dissolution without any instability such as flocculation and aggregation. The above results show that the water-dispersible plant sterol ester microcapsules prepared by the selected emulsifier-stabilizer combination have good re-dissolution stability.

[0136] Example 3: Preparation of water-dispersible phytosterol ester microcapsule solid beverage

[0137] The water-dispersible plant sterol ester microcapsules prepared by the GEL-SA combination and the SPI-CMC-Na combination in Example 2 were selected as representatives and mixed with orange juice powder, milk tea powder, green tea powder, soy milk powder, probiotic powder, coconut powder, strawberry powder, germ powder and antioxidants (see Table 8 for the proportions). Among them, the water-dispersible plant sterol ester microcapsules are 5 to 6 parts, the orange juice powder, milk tea powder, green tea powder, soy milk powder, probiotic powder, coconut powder, strawberry powder, and germ powder are 93.8 to 94.8 parts, and the antioxidant is 0.2 parts. After mixing with a BPV5-V mixer (Baopai Technology Co., Ltd.), different water-dispersible plant sterol ester microcapsule solid beverages are obtained. Take 25g of sample respectively, add 200mL70℃ warm water, stir at 400rpm for 5 minutes, and observe the dissolution, dispersion and agglomeration of various solid beverages in water. It can be seen from Table 8 that the water-dispersible plant sterol ester microcapsules and the corresponding solid beverages prepared therefrom have the advantages of good solubility, good dispersibility and low agglomeration.

[0138] Table 8 Main formula and preparation performance of water-dispersible plant sterol ester microcapsule solid beverage

[0139]

[0140] It should be understood that although this specification is described according to various embodiments, not every embodiment contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0141] The series of detailed descriptions listed above are only specific descriptions of feasible embodiments of the present invention. They are not intended to limit the scope of protection of the present invention. All equivalent embodiments or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing phytosterol ester microcapsules, characterized in that: The following steps are involved: Step S1, preparing an emulsifier solution, wherein the emulsifier is soy protein isolate, gelatin or whey protein isolate, adding phytosterol ester to the emulsifier solution, stirring, shearing and high-pressure homogenization to obtain a phytosterol ester intermediate emulsion, wherein the mass concentration of the emulsifier solution is 1-5%; the mass ratio of the emulsifier solution to the phytosterol ester is 70:30-95:5; the shearing condition is 5000-20000 rpm, the shearing time is 1-4 min; the high-pressure homogenization pressure is 20-50 MPa, and the number of homogenization times is 2-4 times; Step S2, preparing a stabilizer solution, wherein the stabilizer is sodium carboxymethyl cellulose, xanthan gum, high methoxy pectin, sodium alginate or carrageenan, mixing the stabilizer solution with the intermediate emulsion of phytosterol ester obtained in step S1, adding an acidity regulator to adjust the pH to 2-4, stirring and shearing to obtain a phytosterol ester emulsion, wherein the mass concentration of the stabilizer solution is 0.5-3%; and the mass ratio of the stabilizer solution to the intermediate emulsion is 1:3-3:1; Step S3, drying the phytosterol ester emulsion to obtain water-dispersible phytosterol ester microcapsules.

2. The method for preparing phytosterol ester microcapsules according to claim 1, characterized in that: The drying method is spray drying or freeze drying.

3. The method for preparing phytosterol ester microcapsules according to claim 1, characterized in that: The acidity regulator is hydrochloric acid, citric acid, malic acid or acetic acid.

4. A plant sterol ester microcapsule, characterized in that: Prepared according to the method for preparing phytosterol ester microcapsules according to any one of claims 1 to 3; The phytosterol ester microcapsules include phytosterol esters, emulsifiers, stabilizers and acidity regulators; The emulsifier is soy protein isolate, gelatin or whey protein isolate, the emulsifier is prepared into a solution, the mass concentration of the emulsifier solution is 1-5%, and the mass ratio of the emulsifier solution to the phytosterol ester is 70:30-95:5; The plant sterol ester is added to the emulsifier solution, and the plant sterol ester intermediate emulsion can be obtained through stirring, shearing and high-pressure homogenization; The stabilizer is sodium carboxymethyl cellulose, xanthan gum, high methoxy pectin, sodium alginate or carrageenan, and the stabilizer is prepared into a stabilizer solution, the mass concentration of the stabilizer solution is 0.5-3%, and the mass ratio of the stabilizer solution to the intermediate emulsion is 1:3-3:1; The acidity regulator is used to adjust the pH after the stabilizer solution and the intermediate emulsion are mixed, and the pH range is 2-4.

5. An application of phytosterol ester microcapsules, characterized in that: The phytosterol ester microcapsules are prepared according to the method for preparing phytosterol ester microcapsules according to any one of claims 1 to 3, and the phytosterol ester microcapsules are used in the preparation of food, cosmetics, medicine, and feed.

6. The use of the phytosterol ester microcapsules according to claim 5, characterized in that: Application of the plant sterol ester microcapsules in solid beverages.

7. A solid beverage, characterized in that: The phytosterol ester microcapsules are prepared by the preparation method of the phytosterol ester microcapsules according to any one of claims 1 to 3.

8. The solid beverage according to claim 7, characterized in that The invention comprises the following components by weight: 5-6 parts of plant sterol ester microcapsules, 93.8-94.8 parts of beverage powder and 0.2 parts of antioxidant.

Images