A kind of modulated milk containing probiotics and preparation method thereof

Abstract

The present invention discloses a modulated milk containing probiotics and a preparation method thereof, and belongs to the field of microfluidic preparation. The preparation method comprises: 1) dissolving lac in ethanol; 2) adding probiotic powder to the lac / ethanol solution obtained in step 1); 3) dissolving chitosan in water; 4) rapidly mixing the lac / probiotic / ethanol solution obtained in step 2) and the chitosan aqueous solution obtained in step 3) through a microfluidic channel to obtain a dispersion of chitosan / lac / probiotic nanocapsules in water, and obtaining probiotic nanocapsules after drying; 5) mixing the probiotic nanocapsules with water to obtain a mixed solution A; 6) homogenizing the mixed solution A with microfluidics; 7) UHT ultra-high temperature instantaneous sterilization and cooling. The present invention effectively improves the stability of probiotics in modulated milk and the survival rate in the gastrointestinal tract by preparing probiotics into nanocapsules. Compared with traditional probiotic products, the present invention has simple ingredients and ensures the safety of modulated milk.

Description

Technical Field

[0001] The invention relates to the field of microfluidics technology and preparation of modulated milk, and in particular to a modulated milk containing composite probiotics and a preparation method thereof. Background Art

[0002] Formulated milk refers to a liquid product made with no less than 80% raw cow (sheep) milk or reconstituted milk as the main raw material, other raw materials or food additives or nutritional enhancers added, and appropriate sterilization or disinfection processes (GB25191-2010).

[0003] As an important means of regulating intestinal health, probiotics can promote human health by adjusting the composition and abundance of intestinal flora. Studies have shown that probiotics can enhance intestinal barrier function, regulate the immune system, and improve the intestinal microenvironment, thereby having a positive impact on gastrointestinal health. As modern people pay more attention to intestinal health, the application of probiotics in improving digestive system function and enhancing immunity has become increasingly widespread.

[0004] However, it is challenging for probiotics to exert their functions in the human body through oral administration. Strongly acidic gastric juice, various digestive enzymes and bile salts can cause a large number of probiotics to die, limiting the colonization and proliferation of probiotics in the gastrointestinal tract.

[0005] Studies have found that while people are concerned about intestinal health, they are also more concerned about side effects. It is hoped that the product can improve intestinal health without causing drug dependence. Currently, there are many health products and medicines on the market that improve the intestine. There are formulas that use ordinary foods as raw materials and add medicinal and edible ingredients or other nutritional enhancers or probiotic combinations to promote gastrointestinal health. However, the formula of this type of food is relatively complex, and the proportion of Chinese herbal medicine ingredients is relatively large, which affects the taste and flavor of the product. Therefore, there is an urgent need for a new probiotic product that can effectively improve the survival rate of probiotics in the intestine, while simplifying the formula, optimizing the taste and flavor, and providing a more consumer-acceptable intestinal health improvement solution. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a modulated milk containing probiotics and a preparation method thereof. The present invention not only enables the modulated milk to regulate gastrointestinal function by adding probiotic nanocapsules to the modulated milk, but also does not require the addition of other ingredients, has high safety, few side effects, and good taste and flavor.

[0007] According to a first aspect of the present invention, the present invention provides a method for preparing a modulated milk containing probiotics, comprising the following steps:

[0008] 1) dissolving shellac in ethanol to obtain a shellac / ethanol solution;

[0009] 2) adding the probiotic powder to the shellac / ethanol solution obtained in step 1) to obtain a shellac / probiotic / ethanol solution;

[0010] 3) dissolving chitosan in water to obtain a chitosan aqueous solution;

[0011] 4) the shellac / probiotics / ethanol solution obtained in step 2) and the chitosan aqueous solution obtained in step 3) are quickly mixed through a microfluidic channel to perform solvent exchange, thereby obtaining a dispersion of chitosan / shellac / probiotics nanocapsules in water, and drying to obtain probiotics nanocapsules;

[0012] 5) mixing the probiotic nanocapsules with water to obtain a mixed solution A;

[0013] 6) Mixing the mixed solution A with raw milk and homogenizing the mixture to obtain a mixed solution B;

[0014] 7) The mixed solution B is subjected to UHT ultra-high temperature instantaneous sterilization, and after cooling, a modulated milk containing probiotics is obtained.

[0015] The present invention adopts a nanometer coprecipitation method under rapid mixing as a preparation method, which is an effective method for obtaining biocompatible nanoparticles of the present invention. The method can obtain different particle carriers by controlling phase separation through interfacial tension. Since nanoparticles have a large specific surface area and surface energy, they are very easy to agglomerate during the preparation and storage process, and have poor stability. For this reason, the present invention introduces shellac and chitosan in the preparation process, and optimizes the concentration and mixing conditions of each solution involved in the preparation process to improve the dispersibility and stability of the nanoparticles in the liquid medium. Among them, shellac has the properties of being easily soluble in ethanol, insoluble in water, biocompatible, and negatively charged. Chitosan is positively charged and has high biocompatibility.

[0016] On the other hand, the present invention also provides a probiotics modulated milk prepared according to the above preparation method.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] Compared with the conventional nano-coprecipitation method for preparing particles, the present invention uses natural-source lac, which has a certain amphiphilicity and is soluble in a certain proportion of water-ethanol solution, and its solubility will drop sharply only when the water content is greater than 25%. The present invention uses this characteristic to prepare particles by nano-coprecipitation using lac / probiotics / ethanol solution and chitosan aqueous solution. During the mixing process of the two solutions, due to the amphiphilicity of lac, lac will grow and nucleate on the surface of the probiotics, and chitosan will be electrostatically adsorbed on the lac nanoparticles to form chitosan / lac / probiotic nanocapsules; at the same time, with the help of rapid mixing in the microfluidic channel, the growth process of lac nanoparticles is much faster than the adsorption time required for electrostatic adsorption of chitosan dissolved in the aqueous phase.

[0019] Chitosan is non-toxic, non-hemolytic, non-irritating, non-pyrogenic, non-mutagenic, and has good biocompatibility and biodegradability. In addition, chitosan has a positive charge, and the pH value of the intestinal cavity is weakly alkaline. Chitosan is easily adsorbed and absorbed by the intestine, thereby promoting the action of probiotics in the intestine to regulate the intestinal flora.

[0020] The present invention can effectively protect the probiotics from the adverse effects of the external environment (such as gastric acid, temperature changes, mechanical stirring, etc.) during the preparation, storage and consumption of the probiotics by encapsulating the probiotics in chitosan / lac nanocapsules. In an alkaline environment, the chitosan / lac / probiotic nanocapsules disintegrate and release the probiotics, achieving the effect of intestinal targeted release, thereby significantly improving the survival rate and bioavailability of the probiotics in the gastrointestinal tract. The probiotics can better reach the intestines to play a role and enhance intestinal health.

[0021] The present invention uses nanocapsule technology, which eliminates the need to add other auxiliary ingredients, such as preservatives, antistaling agents or other chemical additives commonly found in traditional probiotic products, thus ensuring the naturalness and safety of the product. This makes the product purer and avoids possible side effects or allergic reactions caused by additional ingredients. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a microscope image of probiotics dispersed in deionized water;

[0023] Figure 2 Microscope images of chitosan / shellac / probiotic nanocapsules in deionized water;

[0024] Figure 3 The images of chitosan / shellac / probiotic nanocapsules dispersed in hydrochloric acid solution at pH = 3 and sodium hydroxide aqueous solution at pH = 8;

[0025] Figure 4 The images are of probiotic powder dispersed in hydrochloric acid solution with pH=3 and sodium hydroxide aqueous solution with pH=8;

[0026] Figure 5 Images of the shellac / probiotic nanocapsules prepared in Comparative Example 3 dissolved in a hydrochloric acid solution with a pH value of 3 and a sodium hydroxide aqueous solution with a pH value of 8;

[0027] Figure 6 The particle size distribution of chitosan / shellac / probiotics nanocapsules prepared in Comparative Example 2 and the particle size distribution of chitosan / shellac / probiotics nanocapsules prepared in Example 2. DETAILED DESCRIPTION

[0028] The present invention is further described and illustrated below in conjunction with specific embodiments. The embodiments are merely exemplary of the present disclosure and do not define the scope of limitation. The technical features of each embodiment of the present invention may be combined accordingly without conflicting with each other.

[0029] The core idea of ​​the present invention is to innovate the preparation method, and use the nano-coprecipitation method under rapid mixing to prepare a nano-scale, stably dispersed, intestinal-targeted modulated milk containing probiotics. The embodiment of the present invention provides a method for preparing a modulated milk containing probiotics, comprising the following steps:

[0030] 1) dissolving shellac in ethanol to obtain a shellac / ethanol solution;

[0031] 2) adding the probiotic powder to the shellac / ethanol solution obtained in step 1) to obtain a shellac / probiotic / ethanol solution;

[0032] 3) dissolving chitosan in water to obtain a chitosan aqueous solution;

[0033] 4) the shellac / probiotics / ethanol solution obtained in step 2) and the chitosan aqueous solution obtained in step 3) are quickly mixed through a microfluidic channel to perform solvent exchange, thereby obtaining a dispersion of chitosan / shellac / probiotics nanocapsules in water, and drying to obtain probiotics nanocapsules;

[0034] 5) mixing the probiotic nanocapsules with water to obtain a mixed solution A;

[0035] 6) Mixing the mixed solution A with raw milk and homogenizing the mixture to obtain a mixed solution B;

[0036] 7) The mixed solution B is subjected to UHT ultra-high temperature instantaneous sterilization, and after cooling, a modulated milk containing probiotics is obtained.

[0037] Since the solubility of lac drops sharply when the water content is greater than 25%, and the growth process of lac nanoparticles is much faster than the adsorption time required for the electrostatic adsorption of chitosan dissolved in the aqueous phase, the present invention uses lac / probiotics / ethanol solution and chitosan aqueous solution to prepare particles by nano coprecipitation. According to a preferred embodiment of the present invention, in step 1), the concentration of lac in ethanol is 1mg / mL-150mg / mL. Preferably, in step 3), the concentration of chitosan in water is 0.1-0.2mg / ml. Preferably, in step 4), the volume flow rate of the probiotics / lac / ethanol solution when injected into the microchannel water is 0.1mL / h-15mL / h, the volume flow rate of the chitosan aqueous solution when injected is 1.5mL / h-40mL / h, and the volume ratio of the probiotics / lac / ethanol solution to the chitosan aqueous solution water is 1:15-1:300.

[0038] According to a preferred embodiment of the present invention, in step 2), the concentration of the probiotics in the shellac / ethanol solution is 1 mg / mL-5 mg / mL, and the probiotics may be one or more of Lactobacillus acidophilus, Lactobacillus crispatus, Lactobacillus delbrueckii subsp. bulgaricus, Lactobacillus delbrueckii subsp. lactis, Lactobacillus paracasei, Lactobacillus rhamnosus, Streptococcus salivarius subsp. thermophilus, and the like.

[0039] The microfluidic channel is a place for implementing solution mixing and nano-coprecipitation. In a specific embodiment of the present invention, the diameter of the microfluidic channel is 0.08mm-2mm, and the same end of the microfluidic channel has two inlets for injecting two solutions respectively, and the other end of the microfluidic channel obtains the dispersion of the chitosan / lac / probiotic nanocapsules in water. The present invention does not limit the specific form of the microfluidic channel, and it can adopt various channel structures well known in the art, for example, a combination of one or more of a herringbone channel, a butterfly channel, a serpentine channel, and a Tesla channel can be adopted; in the subsequent embodiments of the present invention, a herringbone channel with a diameter of 0.1mm is adopted.

[0040] The purpose of drying in step 4) is to remove water and ethanol to obtain probiotic nanocapsules. Preferably, the size of the probiotic nanocapsules is 80nm-600nm.

[0041] In a preferred embodiment of the present invention, in step 5), the weight ratio of probiotic nanocapsules to water is 1:(1-20). Preferably, in step 6), the weight ratio of mixed solution A to raw milk is 1:(4-99).

[0042] In a preferred embodiment of the present invention, in step 6), the homogenization pressure is 15-25 MPa, more preferably 20-25 MPa, and most preferably 20 MPa; the temperature during homogenization is 50°C-75°C, more preferably 60-65°C, and most preferably 62°C.

[0043] In a preferred embodiment of the present invention, in step 7), the UHT sterilization temperature is 135°C-150°C, more preferably 135-140°C, and most preferably 137°C; the sterilization time is 2-8s, more preferably 3-5s, and most preferably 2s.

[0044] The reagents and raw materials used in the present invention are commercially available.

[0045] Example 1

[0046] 1. Raw material formula (see Table 1):

[0047] Table 1 Raw material formula of Example 1

[0048] raw material Addition amount (wt.%) Raw buffalo milk 90 Probiotic Nanocapsules 1 water 9

[0049] Production steps:

[0050] 1) Dissolve 500 g of shellac in 10 L of ethanol to obtain a 50 mg / mL shellac / ethanol solution;

[0051] 2) adding 10 g of probiotic powder to the shellac / ethanol solution obtained in step 1) to obtain a probiotic / shellac / ethanol solution, wherein the probiotic concentration is 1 mg / mL;

[0052] 3) dissolving 20 g of chitosan in 200 L of deionized water to obtain a 0.1 mg / ml chitosan aqueous solution;

[0053] 4) mixing the shellac / probiotics / ethanol solution obtained in step 2) and the chitosan aqueous solution obtained in step 3) through a herringbone microfluidic channel with a diameter of 0.1 mm, wherein the volume flow rate of the shellac / probiotics / ethanol solution injected into the microfluidic channel is 0.1 mL / h, and the volume flow rate of the chitosan aqueous solution injected into the microfluidic channel is 2 mL / h, to obtain a uniformly mixed dispersion of chitosan / shellac / probiotics nanocapsules in water, and after drying, obtain probiotic nanocapsules with a diameter of 200-400 nm;

[0054] 5) 10 g of probiotic nanocapsules were mixed with 90 g of water to obtain a mixed solution A;

[0055] 6) 100 g of mixed solution A was mixed with 900 g of raw milk and then homogenized to obtain mixed solution B at a homogenization pressure of 22 MPa and a temperature of 50° C.;

[0056] 7) 1 kg of mixed solution B is subjected to UHT ultra-high temperature instantaneous sterilization. In this embodiment, the sterilization temperature is 135° C. and the sterilization time is 3 s;

[0057] 8) Cooling the mixed solution obtained in step 6) to 29° C. and then aseptically filling;

[0058] 9) Packing, inspection and shipment after passing the inspection.

[0059] Example 2

[0060] 1. Raw material formula (see Table 2):

[0061] Table 2 Raw material formula of Example 2

[0062] raw material Addition amount (wt.%) Raw buffalo milk 95 Probiotic Nanocapsules 1 water 4

[0063] Production steps:

[0064] 1) Dissolve 300 g of shellac in 10 L of ethanol to obtain a 30 mg / mL shellac / ethanol solution;

[0065] 2) adding 10 g of probiotic powder to the shellac / ethanol solution obtained in step 1) to obtain a probiotic / shellac / ethanol solution;

[0066] 3) Dissolve 25 g of chitosan in 170 L of deionized water;

[0067] 4) The shellac / probiotics / ethanol solution obtained in step 2) and the chitosan aqueous solution obtained in step 3) are mixed through a herringbone microfluidic channel with a diameter of 0.15 mm, the volume flow rate of the shellac / probiotics / ethanol solution when injected into the microfluidic channel is 0.2 mL / h, and the volume flow rate of the chitosan aqueous solution when injected is 3.4 mL / h, to obtain a uniformly mixed dispersion of chitosan / shellac / probiotics nanocapsules in water, such as Figure 1 As shown, probiotic nanocapsules are obtained after drying;

[0068] 5) 10 g of probiotic nanocapsules were mixed with 40 g of water to obtain a mixed solution A;

[0069] 6) 50 g of mixed solution A was mixed with 950 g of raw milk and homogenized to obtain mixed solution B at a pressure of 16 MPa and a temperature of 52° C.;

[0070] 7) 1 kg of mixed solution B is subjected to UHT ultra-high temperature instantaneous sterilization. In this embodiment, the sterilization temperature is 136° C. and the sterilization time is 3 s;

[0071] 8) Cooling the mixed solution obtained in step 6) to 28° C. and then aseptically filling;

[0072] 9) Packing, inspection and shipment after passing the inspection.

[0073] Example 3

[0074] 1. Raw material formula (see Table 3):

[0075] Table 3 Raw material formula of Example 3

[0076] raw material Addition amount (wt.%) Raw buffalo milk 92 Probiotic Nanocapsules 2 water 6

[0077] Production steps:

[0078] 1) dissolving 400 g of shellac in 10 L of ethanol to obtain a 40 mg / mL shellac / ethanol solution;

[0079] 2) adding 20 g of probiotic powder to the shellac / ethanol solution obtained in step 1) to obtain a probiotic / shellac / ethanol solution;

[0080] 3) Dissolve 21.6 g of chitosan in 180 L of deionized water;

[0081] 4) mixing the shellac / probiotics / ethanol solution obtained in step 2) and the chitosan aqueous solution obtained in step 3) through a herringbone microfluidic channel with a diameter of 0.12 mm, wherein the volume flow rate of the shellac / probiotics / ethanol solution injected into the microfluidic channel is 0.12 mL / h, and the volume flow rate of the chitosan aqueous solution injected into the microfluidic channel is 2.16 mL / h, to obtain a uniformly mixed dispersion of chitosan / shellac / probiotics nanocapsules in water, and drying to obtain probiotic nanocapsules;

[0082] 5) Mix 20 g of probiotic nanocapsules with 60 g of water to obtain a mixed solution A;

[0083] 6) 80 g of mixed solution A and 920 g of raw milk were mixed and homogenized to obtain mixed solution B at a pressure of 15 MPa and a temperature of 50° C.;

[0084] 7) 1 kg of mixed solution B is subjected to UHT ultra-high temperature instantaneous sterilization. In this embodiment, the sterilization temperature is 135° C. and the sterilization time is 3 s;

[0085] 8) Cooling the mixed solution obtained in step 6) to 29° C. and then aseptically filling;

[0086] 9) Packing, inspection and shipment after passing the inspection.

[0087] Comparative Example 1

[0088] Comparative Example 1 Compared with Example 1, the preparation of probiotic nanocapsules from step 1) to step 4) is not performed. In step 5) of Comparative Example 1, 10 g of probiotic powder is used to replace 10 g of probiotic nanocapsules in Example 1 to prepare mixed solution A, and steps 6) to 9) are the same as those in Example 1. The dispersion of probiotic powder in water in Comparative Example 1 is as follows: Figure 2 shown.

[0089] Comparative Example 2

[0090] Comparative Example 2 is compared with Example 1, except that step 4) of Example 1 is changed to: pour the obtained lac / probiotic / ethanol solution into the chitosan aqueous solution and stir and mix (without using the microfluidic channel of Example 1), the speed of adding the lac / probiotic / ethanol solution to the chitosan aqueous solution is 0.1 mL / h, and the stirring speed is 200 r / min, to obtain a dispersion of chitosan / lac / probiotic nanocapsules in water, and to obtain probiotic nanocapsules after drying. The other steps are the same as in Example 1.

[0091] Comparative Example 3

[0092] Comparative Example 3 is compared with Example 1, except that step 3) of Example 1 is removed, and step 4) of Example 1 is changed to: the probiotics / lac / ethanol solution obtained in step 2) and deionized water are mixed through a microfluidic channel with a diameter of 0.1 mm, the volume flow rate of the lac / probiotics / ethanol solution when injected into the microfluidic channel is 0.1 mL / h, and the volume flow rate of the deionized water when injected is 2 mL / h, and a uniformly mixed dispersion of lac / probiotic nanocapsules in water is obtained, and the probiotic nanocapsules are obtained after drying. The other steps are the same as in Example 1.

[0093] Effect Example 1

[0094] In order to evaluate the intestinal release characteristics of the examples, the chitosan / lac / probiotic nanocapsules prepared in Example 2 and the probiotic nanocapsules prepared in Comparative Examples 1 and 3 were subjected to in vitro release studies, wherein the probiotic powder was directly used in Comparative Example 1 for in vitro release studies. The probiotic nanocapsules were dissolved in acidic (hydrochloric acid solution, pH=3) and alkaline conditions (NaOH solution, pH=8), respectively. The results of the chitosan / lac / probiotic nanocapsules prepared in Example 2 are shown in FIG. Figure 3 As shown in the results, the solubility of chitosan / lac / probiotic nanocapsules at pH = 8 is greater than that at pH = 3, indicating the release characteristics of chitosan / lac / probiotic nanocapsules prepared in Example 2 under alkaline conditions. Figure 4 As shown in the figure, probiotic powder aggregates and loses its activity under acidic conditions and cannot further play a role in the intestine, while probiotics die and rupture under alkaline conditions. Therefore, nano-encapsulation is needed to slowly release the corresponding active substances to improve the intestinal microenvironment.

[0095] The shellac / probiotic nanocapsules prepared in Comparative Example 3 were dissolved in acidic (hydrochloric acid solution, pH=3) and alkaline conditions (NaOH solution, pH=8), and the results were as follows: Figure 5 As shown, it indicates that the shellac / probiotic nanocapsules are well stored under acidic conditions and released under alkaline conditions, verifying the protective effect of shellac on probiotics.

[0096] The charge of the chitosan / shellac / probiotic nanocapsules prepared in Comparative Example 3 and Example 2 was measured, and the results are shown in Table 4, indicating that chitosan was successfully coated on the surface of the shellac / probiotic particles, which not only protected the probiotics but also facilitated their adsorption in the intestine.

[0097] The particle size distribution of the chitosan / lac / probiotics nanocapsules prepared in Comparative Example 2 and the chitosan / lac / probiotics nanocapsules prepared in Example 2 is as follows: Figure 6As shown, the nanocapsules prepared by the microfluidic method have uniform particle size distribution and smaller particle size, which is conducive to the stable storage of its dispersion and less prone to sedimentation. In addition, this phenomenon indirectly verifies that the growth process of shellac nanoparticles in the microfluidic channel is much faster than the adsorption time required for electrostatic adsorption of chitosan dissolved in the aqueous phase, so a single peak appears.

[0098] Table 4

[0099]

[0100] Effect Example 2

[0101] In order to further evaluate the difference between the examples and the comparative examples, the flavor, taste, color and state of the modulated milk prepared in Examples 1-3 and Comparative Examples 1-3 were evaluated three months later, and the evaluation method was in accordance with GB 25191-2010 and GB / T12315-2008. The flavor evaluation was performed with normal milk as a reference. The relevant evaluation results are shown in Table 5.

[0102] Table 5 Evaluation table of Examples 1-3 and Comparative Examples 1-3

[0103]

[0104]

[0105] The following conclusions can be drawn from Table 5: The modulated milk obtained in Examples 1-3 is a uniform liquid without precipitate, indicating that the nano-microcapsules in the obtained modulated milk are not easy to agglomerate and are in a stable state. Compared with Comparative Examples 1-3, the modulated milk obtained in Examples 1-3 has obvious advantages, the product has a pure and uniform color, moderate sweetness, a rich and coordinated milk flavor, and the modulation process is green and efficient. In summary, the present invention has positive and effective significance.

[0106] The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. For ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for preparing a modulated milk containing probiotics, characterized in that: The steps include: 1) dissolving shellac in ethanol to obtain a shellac / ethanol solution; 2) adding the probiotic powder to the shellac / ethanol solution obtained in step 1) to obtain a shellac / probiotic / ethanol solution; 3) dissolving chitosan in water to obtain a chitosan aqueous solution; 4) the shellac / probiotics / ethanol solution obtained in step 2) and the chitosan aqueous solution obtained in step 3) are quickly mixed through a microfluidic channel to perform solvent exchange, thereby obtaining a dispersion of chitosan / shellac / probiotics nanocapsules in water, and drying to obtain probiotics nanocapsules; 5) mixing the probiotic nanocapsules with water to obtain a mixed solution A; 6) Mixing the mixed solution A with raw milk and homogenizing the mixture to obtain a mixed solution B; 7) The mixed solution B is subjected to UHT ultra-high temperature instantaneous sterilization, and after cooling, a modulated milk containing probiotics is obtained.

2. The preparation method according to claim 1, characterized in that: The concentration of shellac in ethanol in step 1) is 1 mg / mL-150 mg / mL.

3. The preparation method according to claim 1, characterized in that: In the step 2), the concentration of the probiotics in the shellac / ethanol solution is 1 mg / mL-5 mg / mL, and the probiotics can be one or more of Lactobacillus acidophilus, Lactobacillus crispatus, Lactobacillus delbrueckii subsp. bulgaricus, Lactobacillus delbrueckii subsp. lactis, Lactobacillus paracasei, Lactobacillus rhamnosus, Streptococcus salivarius subsp. thermophilus, etc.

4. The preparation method according to claim 1, characterized in that: The concentration of chitosan in water in step 3) is 0.1-0.2 mg / ml.

5. The preparation method according to claim 1, characterized in that: In step 4), the diameter of the microfluidic channel is 0.08 mm-2 mm, and the same end of the microfluidic channel has two inlets for injecting two solutions respectively, and the other end of the microfluidic channel obtains the dispersion of the chitosan / lac / probiotic nanocapsules in water.

6. The preparation method according to claim 1, characterized in that: In the step 4), the volume flow rate of the probiotics / shellac / ethanol solution when injected into the microchannel is 0.1 mL / h-1 mL / h, the volume flow rate of the chitosan aqueous solution when injected is 1.5 mL / h-40 mL / h, and the volume ratio of the probiotics / shellac / ethanol solution to the chitosan aqueous solution is 1:15-1:

300.

7. The preparation method according to claim 1, characterized in that: In the step 4), the size of the probiotic nanocapsules is 80nm-600nm.

8. The preparation method according to claim 1, characterized in that: In the step 5), the weight ratio of the probiotic nanocapsules to water is 1:(1-20).

9. The preparation method according to claim 1, characterized in that: In the step 6), the weight ratio of the mixed solution A to the raw milk is 1:(4-99); the homogenization pressure is 15-25 MPa, and the temperature during homogenization is 50° C.-75° C.

10. The preparation method according to claim 1, characterized in that: In the step 7), the UHT ultra-high temperature instantaneous sterilization temperature is 135° C.-150° C., and the sterilization time is 2-8 seconds.

11. A modulated milk containing probiotics prepared by the method according to any one of claims 1 to 10.

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