Vitamin D and tea polyphenol co-delivery microcapsule for whole grain solid food and preparation method thereof

Abstract

The invention discloses a vitamin D and tea polyphenol co-delivery microcapsule for whole grain solid food and a preparation method thereof. The method comprises the following steps: (1) adding NaCl and tea polyphenol into water for dissolving to obtain a water phase A; adding polyglycerol poly-grate alkyd ester into grease, and then adding vitamin D to obtain an oil phase B; adding protein into water for dissolving, and hydrating overnight to obtain a water phase C; pectin and maltodextrin are added into water to be dissolved, and a water phase D is obtained; (2) dropwise adding the water phase A into the oil phase B while stirring, and then performing ultrasonic treatment to obtain W / O emulsion; (3) mixing the W / O emulsion with the water phase C, performing ultrasonic treatment, and dropwise adding the water phase D into the mixture to obtain W / O / W emulsion; and (4) drying the W / O / W emulsion to obtain the microcapsule. The microcapsule disclosed by the invention can realize nutrient enrichment of whole grain food, is good in storage stability and long in shelf life, and can be popularized and applied to the field of food and medicine preparation.

Description

Technical Field

[0001] The present invention belongs to the technical fields of functional foods and pharmaceutical processing, and particularly relates to a microcapsule for co-delivering vitamin D and tea polyphenols in whole grain solid foods and a preparation method thereof. Background Art

[0002] With the promotion of the construction of Healthy China, the country advocates the implementation of the whole grain action, and whole grains are becoming increasingly popular in the consumer market. More and more people choose whole grains as their staple food. It is reported that whole grains can play a positive role in reducing the risks of obesity, type II diabetes, cardiovascular diseases and cancer, which is mainly attributed to dietary fiber and various micronutrients present in bran and germ. However, whole grains are naturally deficient in fat-soluble vitamin D. Long-term consumption of whole grain foods as the staple food may lead to vitamin D deficiency due to insufficient intake of fat-soluble vitamin D. In addition, due to its high dietary fiber content, it may lead to excessive intake of dietary fiber, which in turn causes some adverse reactions such as flatulence and abdominal pain, and a high dietary fiber diet is not very friendly to patients with functional gastrointestinal diseases.

[0003] Dietary polyphenols, as a class of secondary metabolites with polyphenol structures widely present in plants, have a wide range of biological functions, including antioxidant, anti-inflammatory and anti-cancer effects, and have important prospects in the prevention and treatment of various chronic diseases. In whole grains, polyphenols often exist in the form of bound polyphenols, and their bioavailability is relatively low compared to free polyphenols. Therefore, adding exogenous polyphenols to whole grain foods helps to exert their functional activities. As one of the most common water-soluble polyphenols, tea polyphenols can prevent or relieve functional gastrointestinal diseases through antioxidant, immunomodulatory, intestinal flora regulation and other pathways. Therefore, for the problem that the above-mentioned whole grain diet is not friendly to patients with functional gastrointestinal diseases, tea polyphenols can be used for prevention. However, the stability of vitamin D and tea polyphenols is poor, they are sensitive to some environmental factors, and may also be degraded in large amounts in the gastrointestinal tract, resulting in low oral bioavailability. Among them, microcapsules are semi-permeable or sealed micro "containers" or "packaging materials" with polymer wall shells that can encapsulate and protect certain substances, which can encapsulate active ingredients in tiny sealed capsules to achieve controlled release of bioactive substances under special conditions.

[0004] In summary, microcapsules can achieve co-delivery of vitamin D and tea polyphenols and be applied to whole grain solid foods, thereby realizing nutritional fortification of whole grain foods. Summary of the Invention

[0005] In order to overcome the nutritional limitations of the above-mentioned whole grain foods, the primary object of the present invention is to propose a preparation method of a microcapsule for co-delivering vitamin D and tea polyphenols in whole grain solid foods.

[0006] Another object of the present invention is to provide a microcapsule for co-delivering vitamin D and tea polyphenols prepared by the above method. The microcapsule has good storage stability, a long shelf life, and can achieve sustained release and programmed release of active ingredients during the intestinal digestion stage.

[0007] Another object of the present invention is to provide the application of the above microcapsule for co-delivering vitamin D and tea polyphenols in the fields of food and drug preparation.

[0008] The object of the present invention is achieved by the following solutions.

[0009] A preparation method of a microcapsule for co-delivering vitamin D and tea polyphenols for whole grain solid foods, comprising the following steps:

[0010] (1) Dissolve NaCl and tea polyphenols in water to obtain aqueous phase A; add polyglyceryl polyricinoleate to oil, dissolve it by water bath heating, cool it, add vitamin D, and stir to dissolve to obtain oil phase B; add protein to water, stir to dissolve, and hydrate overnight to obtain aqueous phase C; dissolve pectin and maltodextrin in water to obtain aqueous phase D;

[0011] (2) While dropping aqueous phase A into oil phase B, stir, and then subject the oil-water mixture to high-speed shear emulsification and ultrasonic treatment to obtain a W / O emulsion;

[0012] (3) Mix the W / O emulsion with aqueous phase C, perform high-speed shear emulsification and ultrasonic treatment to obtain a W / O / W emulsion stabilized by protein, and drop aqueous phase D into it and stir to obtain a W / O / W emulsion stabilized by protein and polysaccharide;

[0013] (4) Perform vacuum freeze-drying or spray-drying on the W / O / W emulsion to obtain the microcapsule;

[0014] In the aqueous phase A, the concentration of NaCl is 1-4 wt%, and the concentration of tea polyphenols is 0.1-4 wt%;

[0015] In the oil phase B, the concentration of polyglyceryl polyricinoleate is 3-5 wt%, and the concentration of vitamin D is 0.1-1 wt%;

[0016] In the aqueous phase C, the concentration of protein is 1-3 wt%;

[0017] In the aqueous phase D, the concentration of pectin is 1-3 wt%, and the concentration of maltodextrin is 1-3 wt%;

[0018] In step (2), the volume ratio of the used aqueous phase A to the oil phase B is 10:90-40:60;

[0019] In step (3), the volume ratio of the used W / O emulsion to the aqueous phase C is 20:80 to 40:60, preferably 30:70; the volume ratio of the used aqueous phase D to the W / O / W emulsion stabilized by protein is 2:1 to 1:2.

[0020] Preferably, the oil and fat is at least one of rapeseed oil, soybean oil and olive oil.

[0021] Preferably, the protein is at least one of whey protein and whey protein fiber.

[0022] Preferably, in step (1), the protein is added to water and stirred to dissolve, the pH is adjusted to 2.0 with hydrochloric acid, and then hydrated overnight to obtain the aqueous phase C; or the protein is added to water and stirred evenly, the pH is adjusted to 2.0 with hydrochloric acid, then hydrated overnight, centrifuged, and the supernatant is taken and heated in a water bath at 80 - 95 °C for 12 - 24 h to obtain the aqueous phase C.

[0023] Preferably, in step (2), the shearing speed of the high-speed shearing is 8000 - 15000 r / min and the time is 2 - 5 min; the ultrasonic power of the ultrasonic treatment is 200 - 500 W and the time is 7 - 14 min.

[0024] Preferably, in step (3), the shearing speed of the high-speed shearing is 5000 - 10000 r / min and the time is 2 - 3 min; the ultrasonic power of the ultrasonic treatment is 200 - 300 W and the time is 5 - 7 min; the stirring speed is 700 - 1500 r / min and the time is 8 - 24 h.

[0025] Preferably, in step (4), the pre-freezing temperature of the vacuum freeze-drying is -80 °C and the time is 8 - 12 h; the vacuum freeze-drying temperature is -80 °C and the time is 72 - 96 h; the inlet air temperature of the spray drying is 140 - 170 °C and the pressure is 0.1 - 0.3 MPa.

[0026] A microcapsule for co-delivering vitamin D and tea polyphenols for whole grain solid foods is prepared by the preparation method described in any one of the above.

[0027] Application of the microcapsule for co-delivering vitamin D and tea polyphenols for whole grain solid foods described above in the fields of food and medicine preparation.

[0028] The method of the present invention uses a two-step method to prepare an emulsion, and utilizes the characteristic that whey protein or whey protein fiber and pectin have different charges under low pH conditions, and through electrostatic interaction, a stable and firm double-layer interfacial film structure is formed on the surface of the droplets. The microcapsules are prepared by freeze-drying and spray-drying methods respectively, and the microcapsules have a sustained release effect in the simulated intestinal digestion stage.

[0029] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0030] (1) The method for preparing microcapsules provided by the present invention is based on double emulsion, and microcapsules are prepared by spray drying or freeze drying, realizing the co-delivery of fat-soluble vitamin D and water-soluble tea polyphenols, and significantly improving the processing stability and storage stability of vitamin D and tea polyphenols.

[0031] (2) The microcapsules provided by the method of the present invention involve proteins, polysaccharides and oils with wide sources, affordable prices, good nutritional properties, and can be biodegradable.

[0032] (3) The microcapsules provided by the present invention have good storage stability and a long shelf life. After 60 days of storage, the retention rate of active ingredients is still relatively high.

[0033] (4) The microcapsules provided by the present invention can achieve the nutritional fortification of whole grains and can be applied to the small intestine-targeted sustained and controlled release delivery system. Description of the Drawings

[0034] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation to the present invention.

[0035] Figure 1 It is the scanning electron microscope image of the microcapsules prepared in Examples 1 to 4 of the present invention.

[0036] Figure 2 It is the standard curve graph of tea polyphenols required for the performance test of the examples of the present invention.

[0037] Figure 3 It is the standard curve graph of vitamin D required for the performance test of the examples of the present invention.

[0038] Figure 4 It is the infrared spectrum graph of the microcapsules prepared in Examples 1 to 4 of the present invention, tea polyphenols and vitamin D.

[0039] Figure 5 It is the microscopic structure graph of the emulsion formed after the microcapsules prepared in Examples 1 to 4 of the present invention are redissolved.

[0040] Figure 6 It is the retention rate graph of tea polyphenols of the microcapsules prepared in Examples 1 to 4 of the present invention at different pH values.

[0041] Figure 7 It is the retention rate graph of vitamin D of the microcapsules prepared in Examples 1 to 4 of the present invention at different pH values.

[0042] Figure 8Release rate curves of tea polyphenols in the in vitro digestion of the microcapsules prepared in Examples 1-4 of the present invention.

[0043] Figure 9 Release rate curves of vitamin D in the in vitro digestion of the microcapsules prepared in Examples 1-4 of the present invention. Detailed implementation manners

[0044] The present invention will be further described in detail below with reference to the accompanying drawings. The embodiments cannot be enumerated one by one here, but the implementation manners of the present invention are not limited to the following embodiments.

[0045] Example 1

[0046] This example provides a microcapsule for co-delivering tea polyphenols and vitamin D that can be used in whole grain solid foods. The specific preparation process is as follows:

[0047] (1) Dissolve 3 wt% NaCl and 4 wt% tea polyphenols in water to obtain aqueous phase A. Add 4 wt% polyglycerol polyricinoleate to rapeseed oil, dissolve it by heating in a water bath at 55 °C with magnetic stirring, and after cooling, add 0.5 wt% vitamin D and dissolve it with magnetic stirring to obtain oil phase B. Add 2 wt% whey protein to water and stir magnetically, adjust the pH to 2.0, hydrate overnight, centrifuge, and take the supernatant to obtain aqueous phase C. Dissolve 1 wt% pectin and 2 wt% maltodextrin in water to obtain aqueous phase D;

[0048] (2) While dripping aqueous phase A into oil phase B, stir magnetically. The volume ratio of aqueous phase A to oil phase B is 20:80. Subsequently, subject the oil-water mixture to high-speed shear emulsification at 12500 rpm for 3 min and ultrasonic treatment at 300 W for 14 min (3 s on, 3 s off) to obtain a W / O emulsion;

[0049] (3) Mix the W / O emulsion and aqueous phase C according to a volume ratio of 30:70, perform high-speed shear emulsification at 8000 rpm for 2 min, and ultrasonic treatment at 300 W for 7 min (3 s on, 3 s off) to obtain a protein-stabilized W / O / W emulsion. Drop aqueous phase D into the emulsion, where the volume ratio of aqueous phase D to the emulsion is 1:1, and stir magnetically at 1000 r / min for 12 h to obtain a protein- and polysaccharide-stabilized W / O / W emulsion;

[0050] (4) Set the inlet air temperature to 160 °C and the pressure to 0.1 MPa, and perform spray drying on the above emulsion to obtain the microcapsule.

[0051] Example 2

[0052] (1) Dissolve 3 wt% NaCl and 4 wt% tea polyphenols in water to obtain aqueous phase A. Add 4 wt% polyglycerol polyricinoleate to rapeseed oil, dissolve it by heating in a water bath at 55 °C with magnetic stirring, add 0.5 wt% vitamin D after cooling, and dissolve it with magnetic stirring to obtain oil phase B. Add 2 wt% whey protein to water, stir magnetically, adjust the pH to 2.0, hydrate overnight, centrifuge, take the supernatant, and heat it in a water bath at 85 °C for 12 h to obtain aqueous phase C. Dissolve 1 wt% pectin and 2 wt% maltodextrin in water to obtain aqueous phase D;

[0053] (2) While dropping aqueous phase A into oil phase B, stir magnetically. Among them, the volume ratio of aqueous phase A to oil phase B is 20:80. Subsequently, high-speed shear emulsify the oil-water mixture at 12500 rpm for 3 min, and perform ultrasonic treatment at 300 W for 14 min (3 s on, 3 s off) to obtain a W / O emulsion;

[0054] (3) Mix the W / O emulsion and aqueous phase C according to a volume ratio of 30:70, high-speed shear emulsify at 8000 rpm for 2 min, and perform ultrasonic treatment at 300 W for 7 min (3 s on, 3 s off) to obtain a protein-stabilized W / O / W emulsion. Drop aqueous phase D into the emulsion, where the volume ratio of aqueous phase D to the emulsion is 1:1, and stir magnetically at 1000 r / min for 12 h to obtain a protein- and pectin-stabilized W / O / W emulsion;

[0055] (4) Set the inlet air temperature to 160 °C and the pressure to 0.1 MPa, and spray-dry the above emulsion to obtain microcapsules.

[0056] Example 3

[0057] (1) Dissolve 3 wt% NaCl and 4 wt% tea polyphenols in water to obtain aqueous phase A. Add 4 wt% polyglycerol polyricinoleate to rapeseed oil, dissolve it by heating in a water bath at 55 °C with magnetic stirring, add 0.5 wt% vitamin D after cooling, and dissolve it with magnetic stirring to obtain oil phase B. Add 2 wt% whey protein to water, stir magnetically, adjust the pH to 2.0, hydrate overnight, centrifuge, and take the supernatant to obtain aqueous phase C. Dissolve 1 wt% pectin and 2 wt% maltodextrin in water to obtain aqueous phase D;

[0058] (2) While dropping aqueous phase A into oil phase B, stir magnetically. Among them, the volume ratio of aqueous phase A to oil phase B is 20:80. Subsequently, high-speed shear emulsify the oil-water mixture at 12500 rpm for 3 min, and perform ultrasonic treatment at 300 W for 14 min (3 s on, 3 s off) to obtain a W / O emulsion;

[0059] (3) Mix the W / O emulsion and aqueous phase C at a volume ratio of 30:70, and perform high-speed shearing emulsification at 8000 rpm for 2 min, followed by ultrasonic treatment at 300 W for 7 min (3 s on, 3 s off) to obtain a protein-stabilized W / O / W emulsion. Then, add aqueous phase D dropwise into the emulsion, where the volume ratio of aqueous phase D to the emulsion is 1:1, and stir magnetically at 1000 r / min for 12 h to obtain a protein- and pectin-stabilized W / O / W emulsion;

[0060] (4) Place the above emulsion in a -80 °C refrigerator for pre-freezing for 12 h, and then perform vacuum freeze-drying at -80 °C for 96 h to obtain the microcapsules.

[0061] Example 4

[0062] (1) Dissolve 3 wt% NaCl and 4 wt% tea polyphenols in water to obtain aqueous phase A. Add 4 wt% polyglyceryl polyricinoleate to rapeseed oil, heat in a water bath at 55 °C with magnetic stirring to dissolve, cool, and then add 0.5 wt% vitamin D and stir magnetically to dissolve to obtain oil phase B. Add 2 wt% whey protein to water and stir magnetically, adjust the pH to 2.0, hydrate overnight, centrifuge, take the supernatant, and heat in a water bath at 85 °C for 12 h to obtain aqueous phase C. Dissolve 1 wt% pectin and 2 wt% maltodextrin in water to obtain aqueous phase D;

[0063] (2) While dropping aqueous phase A into oil phase B, stir magnetically. The volume ratio of aqueous phase A to oil phase B is 20:80. Subsequently, perform high-speed shearing emulsification on the oil-water mixture at 12500 rpm for 3 min, followed by ultrasonic treatment at 300 W for 14 min (3 s on, 3 s off) to obtain a W / O emulsion;

[0064] (3) Mix the W / O emulsion and aqueous phase C at a volume ratio of 30:70, and perform high-speed shearing emulsification at 8000 rpm for 2 min, followed by ultrasonic treatment at 300 W for 7 min (3 s on, 3 s off) to obtain a protein-stabilized W / O / W emulsion. Then, add aqueous phase D dropwise into the emulsion, where the volume ratio of aqueous phase D to the emulsion is 1:1, and stir magnetically at 1000 r / min for 12 h to obtain a protein- and pectin-stabilized W / O / W emulsion;

[0065] (4) Place the above emulsion in a -80 °C refrigerator for pre-freezing for 12 h, and then perform vacuum freeze-drying at -80 °C for 96 h to obtain the microcapsules.

[0066] Comparative Example 1

[0067] (1) Dissolve 3 wt% NaCl and 4 wt% tea polyphenols in water to obtain aqueous phase A. Add 4 wt% polyglycerol polyricinoleate to rapeseed oil, dissolve it by heating in a water bath at 55 °C with magnetic stirring, add 0.5 wt% vitamin D after cooling, and dissolve it with magnetic stirring to obtain oil phase B. Add 2 wt% whey protein to water, stir magnetically, adjust the pH to 2.0, hydrate overnight, centrifuge, and take the supernatant to obtain aqueous phase C. Dissolve 1 wt% pectin in water to obtain aqueous phase D.

[0068] (2) While dropping aqueous phase A into oil phase B, stir magnetically. The volume ratio of aqueous phase A to oil phase B is 20:80. Subsequently, subject the oil-water mixture to high-speed shear emulsification at 12500 rpm for 3 min and ultrasonic treatment at 300 W for 14 min (3 s on, 3 s off) to obtain a W / O emulsion.

[0069] (3) Mix the W / O emulsion and aqueous phase C at a volume ratio of 30:70, subject it to high-speed shear emulsification at 8000 rpm for 2 min and ultrasonic treatment at 300 W for 7 min (3 s on, 3 s off) to obtain a protein-stabilized W / O / W emulsion. Drop aqueous phase D into the emulsion, where the volume ratio of aqueous phase D to the emulsion is 1:1, and stir magnetically at 1000 r / min for 12 h to obtain a protein- and pectin-stabilized W / O / W emulsion.

[0070] (4) Set the inlet air temperature to 160 °C and the pressure to 0.1 MPa, and spray-dry the above emulsion.

[0071] It was found that the protein- and pectin-stabilized W / O / W emulsion provided in Comparative Example 1 failed to achieve microencapsulation of the emulsion.

[0072] Comparative Example 2

[0073] (1) Dissolve 3 wt% NaCl and 4 wt% tea polyphenols in water to obtain aqueous phase A. Add 4 wt% polyglycerol polyricinoleate to rapeseed oil, dissolve it by heating in a water bath at 55 °C with magnetic stirring, add 0.5 wt% vitamin D after cooling, and dissolve it with magnetic stirring to obtain oil phase B. Add 2 wt% whey protein to water, stir magnetically, adjust the pH to 2.0, hydrate overnight, centrifuge, and take the supernatant to obtain aqueous phase C.

[0074] (2) While dropping aqueous phase A into oil phase B, stir magnetically. The volume ratio of aqueous phase A to oil phase B is 20:80. Subsequently, subject the oil-water mixture to high-speed shear emulsification at 12500 rpm for 3 min and ultrasonic treatment at 300 W for 14 min (3 s on, 3 s off) to obtain a W / O emulsion.

[0075] (3) Mix the W / O emulsion and aqueous phase C in a volume ratio of 10:90, and perform high-speed shear emulsification at 8000 rpm for 2 min, followed by ultrasonic treatment at 300 W for 7 min (3 s on, 3 s off) to obtain a protein-stabilized W / O / W emulsion.

[0076] It was found that for the W / O / W emulsion stabilized by protein provided in Comparative Example 2, the volume ratio of the W / O emulsion to aqueous phase C was 10:90, and its encapsulation effect on tea polyphenols and vitamin D was worse than that of the protein-stabilized emulsion prepared in Example 1.

[0077] Comparative Example 3

[0078] (1) Dissolve 3 wt% NaCl and 4 wt% tea polyphenols in water to obtain aqueous phase A. Add 4 wt% polyglycerol polyricinoleate to rapeseed oil, dissolve it by heating in a water bath at 55 °C with magnetic stirring, and then add 0.5 wt% vitamin D after cooling and dissolve it with magnetic stirring to obtain oil phase B; add 2 wt% whey protein to water and stir magnetically, adjust the pH to 2.0, hydrate overnight, centrifuge, take the supernatant, and heat it in a water bath at 85 °C for 12 h to obtain aqueous phase C;

[0079] (2) While dripping aqueous phase A into oil phase B, stir magnetically. The volume ratio of aqueous phase A to oil phase B is 20:80. Subsequently, perform high-speed shear emulsification on the oil-water mixture at 12500 rpm for 3 min, followed by ultrasonic treatment at 300 W for 14 min (3 s on, 3 s off) to obtain a W / O emulsion;

[0080] (3) Mix the W / O emulsion and aqueous phase C in a volume ratio of 10:90, and perform high-speed shear emulsification at 8000 rpm for 2 min, followed by ultrasonic treatment at 300 W for 7 min (3 s on, 3 s off) to obtain a protein-stabilized W / O / W emulsion.

[0081] It was found that for the W / O / W emulsion stabilized by whey protein fibers provided in Comparative Example 3, the volume ratio of the W / O emulsion to aqueous phase C was 10:90, and its encapsulation effect on tea polyphenols and vitamin D was worse than that of the emulsion stabilized by whey protein fibers prepared in Example 2.

[0082] Testing method

[0083] Determination of the powder flowability and microscopic morphology of microcapsules for co-delivering tea polyphenols and vitamin D in whole grain solid foods, including the following steps:

[0084] (1) Take 2 g of the sample and place it in a graduated cylinder, and accurately read the loose volume and the tapped volume. Among them, the bulk density is the ratio of the sample mass to the loose volume, and the tapped density is the ratio of the sample mass to the tapped volume.

[0085] (2) Calculate the Carr index and Hausner ratio based on their bulk density and tapped density. Among them, the Carr index is the ratio of the difference between the tapped density and the bulk density to the tapped density multiplied by 100, and the Hausner ratio is the ratio of the tapped density to the bulk density.

[0086] (3) Take a small amount of microcapsules respectively, stick them on the stage of the scanning electron microscope with conductive glue, and observe them under an accelerating voltage of 3 kV and 10,000 mag after sputtering with gold.

[0087] Measure the bulk density, tapped density, Carr index, and Hausner ratio of the microcapsules prepared in the above Examples 1 to 4. The results are shown in Table 1.

[0088] Table 1

[0089]

[0090]

[0091] Table 1 shows the powder flowability results of the microcapsules for co-delivering tea polyphenols and vitamin D in whole grain solid foods. It can be seen from Table 1 that the microcapsules provided in Examples 1 and 2 using spray drying have larger bulk density and tapped density than the microcapsules provided in Examples 3 and 4 using freeze drying, and their Carr index and Hausner ratio are smaller than those of the microcapsules provided in Examples 3 and 4. Therefore, the microcapsules provided in Examples 1 and 2 have better fluidity and lower adhesiveness.

[0092] The determination of the encapsulation effect of the microcapsules for co-delivering tea polyphenols and vitamin D in whole grain solid foods includes the following steps:

[0093] (1) Weigh 0.5 g of microcapsules, redissolve them in 4.5 mL of water, take 0.5 mL of the redissolved emulsion and mix it with 4.5 mL of absolute ethanol, ultrasonically treat for 20 min, centrifuge at 3000 rpm for 3 min, take 0.5 mL of the supernatant, add 1 mL of 10% Folin-Ciocalteu reagent, react for 3 - 8 min. Add 2 mL of 12.5% sodium carbonate, and let it stand for 1 h. Measure its absorbance value at 765 nm using a microplate reader, and calculate the encapsulation efficiency of tea polyphenols in the microcapsules according to the gallic acid standard curve (as Figure 1 shown);

[0094] (2) Weigh 0.5 g of microcapsules, redissolve them in 4.5 mL of water, take 0.5 mL of the redissolved emulsion and mix it with 4.5 mL of absolute ethanol, ultrasonically treat for 20 min, centrifuge at 3000 rpm for 3 min. Take 0.5 mL of the supernatant, measure its absorbance value at 265 nm using a microplate reader, and calculate the encapsulation efficiency of vitamin D in the microcapsules according to the vitamin D standard curve (as Figure 2 shown);

[0095] (3) Weigh a small amount of tea polyphenols, vitamin D, and microcapsules, mix and grind them with potassium bromide in a ratio of 1:100, press them into tablets, and under the condition that the ambient temperature is 25 °C, scan 64 times in the range of 4000 - 400 cm -1 with a resolution of 4 cm -1 to collect the infrared spectrum of the sample.

[0096] Test the encapsulation efficiency of the microencapsulated tea polyphenols and vitamin D prepared in Examples 1 - 4 above. The results are shown in Table 2.

[0097] Table 2

[0098]

[0099] Table 2 shows the encapsulation efficiency results of a microcapsule for co - delivering tea polyphenols and vitamin D in whole - grain solid foods. It can be seen from Table 2 that the tea polyphenol encapsulation efficiencies of the microcapsules provided in Examples 1 - 4 are not very different, and the encapsulation efficiencies of vitamin D are all higher than 80%. The vitamin D encapsulation efficiency of the microcapsule provided in Example 2 is as high as 93.98 ± 0.38.

[0100] The stability determination of a microcapsule for co - delivering tea polyphenols and vitamin D in whole - grain solid foods includes the following steps:

[0101] (1) Accurately weigh 2 g of the sample, dry it to a constant weight in a vacuum drying oven at 60 °C and then weigh it. The moisture content is the ratio of the lost mass to the original mass of the sample.

[0102] (2) Weigh 0.5 g of the microcapsules, redissolve them in 4.5 mL of water, dilute them 200 times with deionized water, and measure their average particle size and zeta potential at 25 °C using a nanoparticle size analyzer.

[0103] (3) Weigh 0.5 g of the microcapsules, redissolve them in 4.5 mL of water, take a small amount and place it on a glass slide, cover it with a coverslip, and observe it under an optical microscope. Prepare 0.2% nile red staining solution and nile blue staining solution. Take 1 mL of the emulsion, add 50 μL of nile red staining solution and nile blue staining solution respectively to stain the oil phase and protein. Subsequently, take 3 μL of the emulsion sample and place it on a glass slide, cover it with a coverslip, and observe it under a laser confocal microscope under the excitation wavelength conditions of 488 nm and 630 nm.

[0104] (4) Store the microcapsules under normal - temperature and dry conditions for 60 days. Take a small amount of the microcapsules and measure the retention rate of their active ingredients.

[0105] (5) Dissolve the microcapsules in water (0.1 g / mL), adjust the pH to 1, 2, 3, 4, 5, 6, 7, 8 respectively, store them in a 4 °C refrigerator for 6 h, and measure the retention rate of their active ingredients.

[0106] The water content, average particle size, zeta potential of the microcapsules prepared in the above Examples 1 to 4, and the retention rate of the active ingredient after 60 days were tested, and the results are shown in Table 3.

[0107] Table 3

[0108]

[0109] Table 3 shows the stability results of the microcapsules for co-delivering tea polyphenols and vitamin D in whole grain solid foods. It can be seen from Table 3 that the water content of the microcapsules provided in Examples 1 to 4 remained at 2.4 - 3.0%. The microcapsules provided in Examples 1 and 2 were prepared by spray drying. Although their particle size was larger, after 60 days of storage, the retention rate of vitamin D could still be maintained at a higher level. In particular, the microcapsules prepared from whey protein fibers provided in Example 2 (86.66 ± 0.01%). The microcapsules provided in Examples 3 and 4 were prepared by freeze drying, with smaller particle size and better stability.

[0110] The determination of the release rate of the active ingredient in the in vitro digestion behavior of the microcapsules for co-delivering tea polyphenols and vitamin D in whole grain solid foods includes the following steps:

[0111] (1) Prepare simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) according to Table 4. Take 10 mL of the reconstituted emulsion of microcapsules (0.2 g / mL) and mix it thoroughly with 7.5 mL of SGF, and adjust the pH to 3.00 ± 0.05. Add 1.6 mL of pepsin (2000 U / mL), 5 μL of CaCl2, and 895 μL of water. Use a shaker for constant temperature heating and react at 37 °C and 200 rpm for 2 h.

[0112] (2) Add 5.5 mL of simulated intestinal fluid and 1.25 mL of bile salt extract (160 mg / mL) to the 10 mL sample of gastric digestive fluid in sequence, and adjust the pH to 7.00 ± 0.05. Subsequently, add 2.5 mL of lipase (1600 U / mL) and trypsin solution (800 U / mL), 20 μL of calcium chloride and water. The prepared SIF will decompose free fatty acids during digestion, so NaOH solution (0.1 mol / L) is used to neutralize the free fatty acids during this process to maintain the system pH at about 7.0, and stir in a 37 °C water bath at 200 rpm for 6 h. Samples are taken immediately after 0, 1, 2, 3, 4, 5, and 6 h of digestion in the simulated intestinal fluid to measure the release rates of tea polyphenols and vitamin D.

[0113] Table 4 Formulations of SGF and SIF

[0114]

[0115] Determination of the particle size, zeta potential and encapsulation efficiency of active ingredients of a W / O / W emulsion co-loaded with tea polyphenols and vitamin D, comprising the following steps:

[0116] (1) Take 0.5 mL of the emulsion and mix it with 4.5 mL of absolute ethanol, ultrasonically treat for 20 min, and centrifuge at 3000 rpm for 3 min. Take 0.5 mL of the supernatant, add 1 mL of 10% Folin-Ciocalteu reagent, react for 3 - 8 min. Add 2 mL of 12.5% sodium carbonate, and let stand for 1 h. Measure the absorbance value at 765 nm using a microplate reader, and calculate the encapsulation efficiency of tea polyphenols in the microcapsules according to the gallic acid standard curve (as Figure 1 shown);

[0117] (2) Take 0.5 mL of the reconstituted emulsion and mix it with 4.5 mL of absolute ethanol, ultrasonically treat for 20 min, and centrifuge at 3000 rpm for 3 min. Take 0.5 mL of the supernatant, measure the absorbance value at 265 nm using a microplate reader, and calculate the encapsulation efficiency of vitamin D in the microcapsules according to the vitamin D standard curve (as Figure 2 shown).

[0118] The encapsulation efficiency of active ingredients of the W / O / W emulsions stabilized only by protein prepared in Examples 1 - 2 and the W / O / W emulsions prepared in Comparative Examples 2 - 3 was tested, and the results are shown in Table 5.

[0119] Table 5

[0120]

[0121] Table 5 shows the results of the encapsulation efficiency of active ingredients of a W / O / W emulsion co-loaded with tea polyphenols and vitamin D stabilized only by protein. As can be seen from Table 5, compared with the emulsions provided in Comparative Examples 2 and 3, the W / O / W emulsions stabilized only by protein prepared in Examples 1 - 2 have a better encapsulation effect on active ingredients, and the encapsulation efficiencies of tea polyphenols and vitamin D are both above 80%.

[0122] Figure 1 Scanning electron micrographs of microcapsules for co-delivering tea polyphenols and vitamin D in whole grain solid foods provided in Examples 1 - 4 of the present invention. As Figure 1 can be seen, the microcapsules provided in Examples 1 and 2 were prepared by spray drying, presenting an uneven surface morphology with small indentations and wrinkles on the surface; the microcapsules provided in Examples 3 and 4 were prepared by vacuum freeze drying, and both showed an irregular flaky structure with internal pores, which is usually related to the sublimation of ice crystals during the freeze drying process.

[0123] Figure 2 andFigure 3 The standard curves of gallic acid and vitamin D required for the performance test of the embodiments of the present invention are as follows. From Figure 2 and 3 it can be seen that the relationship between the gallic acid concentration (x1) and the absorbance (y1) is y1 = 20.824x1 + 0.1039, and the relationship between the vitamin D concentration (x2) and the absorbance (y2) is y2 = 20.824x2 + 0.1039.

[0124] Figure 4 The infrared spectra of the microcapsules provided in Examples 1-4 of the present invention and vitamin D and tea polyphenols are as follows. From Figure 4 it can be seen that with the introduction of tea polyphenols and vitamin D, the intensities of the characteristic absorption peaks near 3600-3000 cm -1 , 3000-2800 cm -1 and 1465 cm -1 increase. Therefore, the microcapsules provided in Examples 1 to 4 have a good encapsulation effect on vitamin D and tea polyphenols.

[0125] Figure 5 The microscopic structures of the emulsions formed after re-dissolving the microcapsules provided in Examples 1 to 4 of the present invention are as follows. From Figure 5 it can be seen that the microcapsules provided in Examples 1 and 2 are prepared by spray drying. After re-dissolution, they still show an obvious "three-compartment two-phase" structure. However, due to the rapid evaporation of water during the drying process, the solids in the emulsion can form particle structures and aggregate in a short time. After the microcapsules provided in Examples 3 and 4 are re-dissolved, since the internal and external aqueous phases polymerize during the freeze-drying process of the original emulsion, the number of droplets with a "three-compartment two-phase" structure is small, and there are a large number of droplets with smaller sizes.

[0126] Figure 6 and Figure 7 respectively show the retention rates of tea polyphenols and vitamin D in the microcapsules provided in Examples 1 to 4 of the present invention at different pH values. It can be seen from the figure that as the pH increases from 1 to 8, the retention rate of tea polyphenols in the microcapsules provided in Examples 1 to 4 changes little, and the retention rate of vitamin D first increases and then decreases. Near pH 3, the retention rate reaches the highest. Therefore, under the conditions of pH 1-4, the microcapsules have good stability and can effectively encapsulate the active ingredients; under the conditions of pH 5-8, the release of the active ingredients can be achieved. It is thus speculated that the microcapsules provided in Examples 1 to 4 can remain stable in the gastric environment and can achieve the programmed release of the active ingredients in the small intestine.

[0127] Figure 8 and Figure 9It is a graph showing the release rates of tea polyphenols and vitamin D of the microcapsules provided in Embodiments 1 to 4 of the present invention during in vitro digestion. As can be seen from the graph, during the entire digestion process, the release rates of tea polyphenols of the four microcapsules remained within the range of 6-14%, with little variation. The release rates of vitamin D of the microcapsules provided in Embodiments 1 to 4 began to increase significantly after 2-3 hours of digestion, and after 6 hours of digestion, their release rates reached 57.67±3.47%, 45.14±0.87%, 49.20±1.50%, and 39.61±1.49% respectively. Therefore, the microcapsules provided in Embodiments 1 to 4 can achieve sustained release of vitamin D in the small intestine.

[0128] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, making equivalent substitutions or changes, should be covered by the protection scope of the present invention.

Claims

1. A method for preparing microcapsules for co - delivering vitamin D and tea polyphenols for whole - grain solid foods, characterized in that, It includes the following steps: (1) Dissolve NaCl and tea polyphenols in water to obtain aqueous phase A; add polyglyceryl polyricinoleate to oil, dissolve it by heating in a water bath, add vitamin D after cooling, and stir to dissolve to obtain oil phase B; add protein to water, stir to dissolve, hydrate overnight to obtain aqueous phase C; add pectin and maltodextrin to water, dissolve to obtain aqueous phase D; (2) While dropping aqueous phase A into oil phase B, stir, then subject the oil-water mixture to high-speed shear emulsification and ultrasonic treatment to obtain a W / O emulsion; (3) Mix the W / O emulsion with aqueous phase C, perform high-speed shear emulsification and ultrasonic treatment to obtain a protein-stabilized W / O / W emulsion, drop aqueous phase D into it, and stir to obtain a protein- and polysaccharide-stabilized W / O / W emulsion; (4) Perform vacuum freeze-drying or spray-drying on the W / O / W emulsion to obtain microcapsules. In the aqueous phase A, the NaCl concentration is 1-4 wt%, and the tea polyphenol concentration is 0.1-4 wt%; In the oil phase B, the polyglyceryl polyricinoleate concentration is 3-5 wt%, and the vitamin D concentration is 0.1-1 wt%; In the aqueous phase C, the protein concentration is 1-3 wt%; In the aqueous phase D, the pectin concentration is 1-3 wt%, and the maltodextrin concentration is 1-3 wt%; In step (2), the volume ratio of the used aqueous phase A to oil phase B is 10:90-40:60; In step (3), the volume ratio of the used W / O emulsion to aqueous phase C is 20:80-40:60; the volume ratio of the used aqueous phase D to the protein-stabilized W / O / W emulsion is 2:1-1:

2.

2. The preparation method of a microcapsule for co-delivering vitamin D and tea polyphenols for whole grain solid foods according to claim 1, characterized in that, The oil is at least one of rapeseed oil, soybean oil, and olive oil.

3. The preparation method of a microcapsule for co-delivering vitamin D and tea polyphenols for whole grain solid foods according to claim 1, wherein, The protein is at least one of whey protein and whey protein fiber.

4. The preparation method of a microcapsule for co-delivering vitamin D and tea polyphenols for whole grain solid foods according to claim 1, wherein, In step (1), add protein to water, stir to dissolve, adjust the pH to 2.0 with hydrochloric acid, then hydrate overnight, centrifuge, and take the supernatant to obtain aqueous phase C; Or add protein to water, stir to dissolve, adjust the pH to 2.0 with hydrochloric acid, then hydrate overnight, centrifuge, take the supernatant, and heat it in a water bath at 80-95 °C for 12-24 h to obtain aqueous phase C.

5. The preparation method of a microcapsule for co-delivering vitamin D and tea polyphenols for whole grain solid foods according to claim 1, characterized in that, In step (2), the shear speed of the high-speed shear is 8000-15000 r / min, and the time is 2-5 min; the ultrasonic power of the ultrasonic treatment is 200-500 W, and the time is 7-14 min.

6. The preparation method of a microcapsule for co-delivering vitamin D and tea polyphenols for whole grain solid foods according to claim 1, wherein, In step (3), the shear speed of the high-speed shear is 5000-10000 r / min, and the time is 2-3 min; the ultrasonic power of the ultrasonic treatment is 200-300 W, and the time is 5-7 min; the stirring speed is 700-1500 r / min, and the time is 8-24 h.

7. The preparation method of a microcapsule for co-delivering vitamin D and tea polyphenols for whole grain solid foods according to claim 1, characterized in that, In step (4), the pre-freezing temperature of the vacuum freeze-drying is -80 °C, and the time is 8-12 h; the vacuum freeze-drying temperature is -80 °C, and the time is 72-96 h.

8. The preparation method of a microcapsule for co-delivering vitamin D and tea polyphenols for whole grain solid foods according to claim 1, characterized in that, In step (4), the inlet air temperature of the spray-drying is 140-170 °C, and the pressure is 0.1-0.3 MPa.

9. A microcapsule for co-delivering vitamin D and tea polyphenols for whole grain solid foods, characterized in that, Prepared by the preparation method according to any one of claims 1-8.

10. Use of the microcapsule for co-delivering vitamin D and tea polyphenols for whole grain solid foods according to claim 9 in the fields of food and medicine preparation.

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