High-multiple nutritional milk and preparation method thereof

Abstract

The present invention relates to the technical field of dairy products, and specifically provides a high-multiple nutritional milk and a preparation method thereof. The preparation method provided by the present invention comprises: separating raw milk fat to obtain skim milk and cream, subjecting the skim milk to three-stage freeze concentration to obtain concentrated milk, and subjecting the concentrated milk to INF sterilization; the INF sterilization temperature is 125-133°C to obtain the high-multiple nutritional milk; the protein content of the high-multiple nutritional milk is greater than 6%. The preparation method provided by the present invention can make the active nutrient retention rate in the product higher than 40%, which can not only increase the nutritional components of raw milk to a higher level, but also retain most of the active nutrients and fresh taste in the raw milk.

Description

Technical Field

[0001] The present invention relates to the technical field of dairy products, in particular to high-nutrient milk and a preparation method thereof. Background Art

[0002] Cow's and goat's milk, as a nutritionally complete food, is rich in various nutrients, including protein and fat, and is an important source of nutrition for humans. However, because raw milk is not only rich in nutrients and active proteins, but also contains certain microorganisms, it must undergo thermal sterilization for both human consumption safety and the storage, transportation, and shelf life of commercial liquid milk. Compared to ultra-high temperature (UHT) sterilization, pasteurization, with its relatively low sterilization intensity, can eliminate harmful microorganisms to a certain extent while retaining most of the immune-active nutrients in raw milk, such as immunoglobulins, lactoferrin, and peroxidase, thereby preserving the active nutrients and fresh flavor of liquid milk to the greatest extent possible.

[0003] At the same time, as people's living standards continue to improve, consumers' demands for nutritional quality are also increasing. The nutritional level of traditional raw milk can no longer fully meet consumers' nutritional needs. Therefore, the industry generally uses certain concentration methods to remove some water from the base raw milk to achieve the desired milk protein nutrition and mellow taste.

[0004] There are two main ways to concentrate cow milk: gas-liquid separation and liquid-liquid separation. Among them, gas-liquid separation is the most common and widely used method for milk processing and concentration. That is, the water in the raw milk is converted into steam by evaporation and then separated from the concentrated liquid phase; the liquid-liquid separation method uses a small molecule membrane to filter out some water and small molecule components to achieve the effect of concentrating the nutrients in the liquid milk.

[0005] Currently, INF sterilization can be used for milk or goat milk concentrated after gas-liquid separation or liquid-liquid separation. However, for liquid milk with a higher concentration ratio, such as liquid milk with a protein content greater than 5%, INF sterilization cannot play a good sterilization role, resulting in poor stability of the liquid milk. Summary of the Invention

[0006] In order to solve the problems of the prior art, the first aspect of the present invention provides a method for preparing high-multiple nutritional milk, comprising: separating raw milk fat to obtain skimmed milk and cream, freeze-concentrating the skimmed milk through a three-stage crystallizer to obtain concentrated milk, and sterilizing the concentrated milk; the sterilization temperature is 125~133℃ to obtain the high-multiple nutritional milk; the protein content in the high-multiple nutritional milk is greater than 6%.

[0007] In the preparation method provided by the present invention, the cream is backfilled into the concentrated milk and then homogenized and sterilized.

[0008] In the preparation method provided by the present invention, the sterilization temperature is 128-131° C., the sterilization time is 0.5-2 s, and preferably the sterilization time is 0.5-1 s.

[0009] Milk with a protein content greater than 5% obtained by concentrating raw milk uses a relatively low-intensity pasteurization process, resulting in poor shelf stability. However, other pasteurization methods also fail to produce stable, high-protein, and highly active milk. This study, for the first time, discovered that the stability, taste, and active nutrients of high-protein raw milk are not only influenced by the pasteurization method, but also by the method used to concentrate the raw milk.

[0010] As a specific embodiment of the present invention, a method for preparing high-nutrient milk comprises:

[0011] (1) Raw milk pretreatment: Purify and sterilize the raw milk, cool it to 4-6°C, and set aside;

[0012] (2) Preparation of skim milk: The raw milk prepared in step (1) is heated to 50-70°C and passed through a fat separator to obtain cream and skim milk. The skim milk is then cooled to 4-8°C and set aside.

[0013] (3) Freeze-concentrating skim milk: passing the skim milk obtained in step (2) through a three-stage crystallizer, filtering the obtained ice crystal mixture, and obtaining concentrated milk;

[0014] (4) INF sterilization: homogenize the concentrated milk obtained in step (3) and sterilize it with INF;

[0015] Or backfill the concentrated milk obtained in step (3) with cream for homogenization and INF sterilization;

[0016] The INF sterilization temperature is 125-133° C., and the INF sterilization time is 0.5-2 seconds. After INF sterilization, the feed liquid is cooled to 4-8° C. to obtain the high-multiple nutritional milk.

[0017] In the preparation method provided by the present invention, the homogenization conditions in step (4) are 220~250bar, the secondary homogenization pressure is 40~50bar, and the homogenization temperature is 55~65℃.

[0018] In the preparation method provided by the present invention, the skim milk obtained in step (2) is crystallized and washed in a first-stage crystallizer to obtain a skim milk concentrate; the skim milk concentrate is crystallized and washed in a second-stage crystallizer to obtain a skim milk concentrated liquid; the skim milk concentrated liquid is crystallized in a third-stage crystallizer and ice crystals are filtered to obtain concentrated milk.

[0019] In the preparation method provided by the present invention, the ice crystal mixture generated by the first-stage crystallizer is washed by a pressure washing column to obtain a lower layer concentrate; the ice crystal mixture generated by the second-stage crystallizer is dissolved and washed by a pressure-free secondary washing column to obtain a skim milk concentrate.

[0020] In the preparation method provided by the present invention, the size of the spherical crystals generated in the first-stage crystallizer is between 0.2 and 1 mm, the ice crystal void ratio is between 35 and 45%, and the ice crystal void ratio in the second-stage crystallizer is between 50 and 55%.

[0021] In a second aspect, the present invention provides a high-nutrient milk, which is prepared by the above-mentioned preparation method.

[0022] The beneficial effects of the present invention are:

[0023] (1) The present invention proposes for the first time a method for preparing high-protein nutritious milk with a protein content greater than 6%. Specifically, firstly, the present invention selects a freeze-concentration method with a solid-liquid separation method in the concentration of raw milk. Secondly, the present invention provides a sterilization method for concentrated milk that is most suitable for freeze-concentration.

[0024] Specifically, the present invention uses low-temperature, low-pressure conditions to freeze and condense water into solid ice crystals based on the different freezing points between water and other nutrients in raw milk. This solid-liquid separation increases the proportion of nutrients in the raw milk. Furthermore, the low-temperature, low-pressure treatment effectively preserves the active nutrients and fresh taste and flavor of the raw milk. Furthermore, the sterilization method provided by the present invention can improve the taste and stability of highly nutritious milk while preserving the active nutrients in the raw milk.

[0025] (2) The current traditional concentration method has a low concentration limit. If the concentration ratio is too high, the flavor of the raw milk will change too much, affecting the taste and flavor of the product. At the same time, it cannot guarantee the retention of active nutrients in the product. The present invention can concentrate high-nutrient milk protein to more than 6.0% through a three-stage crystallization elution concentration device, and then through an INF sterilization process, the active nutrient retention rate in the product can be higher than 40%. It can not only increase the nutritional content of high-nutrient milk to a higher level, but also retain most of the active nutrients and fresh taste in the raw milk. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1It is a flow chart of the process equipment provided by the present invention.

[0028] Figure 2 This is a freeze concentration flow chart provided by the present invention. DETAILED DESCRIPTION

[0029] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0030] Example 1 Whole milk

[0031] The flow chart of the multi-purpose process equipment for this implementation is shown in Figure 1 , the preparation method in this embodiment is as follows:

[0032] (1) Raw milk pretreatment: The raw milk is passed through a milk separator to purify and sterilize the raw milk, and then cooled to 4°C for later use;

[0033] (2) Preparation of skim milk: The raw milk prepared in step (1) is heated to 50°C and passed through a fat separator to obtain cream and skim milk. The skim milk is then cooled to 4-8°C and set aside.

[0034] (3) Skim milk is concentrated into freeze concentration, see the flow chart Figure 2 , specifically:

[0035] The skim milk obtained in step (2) is first crystallized by passing it through a freezing crystallization column in a first-stage crystallizer (freezing temperature set at -4°C ± 2°C). At this time, the gap between the ice crystal bed is about 40%, and the crystals are spherical crystals with a size between 0.2 and 1 mm. The mixture after crystallization is dissolved and washed by a pressure washing column (washing column pressure 1 to 2 bar). The ice crystal mixture is washed into an upper layer of pure crystals and a lower layer of concentrate. The upper layer of pure ice crystals is melted and washed away.

[0036] The remaining lower layer concentrate, i.e. skim milk concentrate, passes through primary filtration and enters the second-stage crystallizer (freezing temperature set at -3±1°C). At this time, the gap between the ice crystal bed reaches 50%. After dissolution and washing in a pressure-free secondary washing column (no pressure can reduce the ice crystals entering the final physical scraper filter), skim milk concentrate is obtained.

[0037] The skim milk concentrate enters the third-stage crystallizer (freezing temperature set at -3±1°C), and after crystallization in the third-stage crystallizer, the ice crystals are filtered through a physical scraper filter (filter pore size 0.05-0.15mm), and the concentrated milk enters the concentrated milk temporary storage tank;

[0038] (4) INF sterilization: The concentrated milk after volume adjustment is backfilled with the corresponding cream and then homogenized and sterilized;

[0039] Homogenization conditions are 220 bar, secondary homogenization pressure 40 bar, and homogenization temperature 55°C;

[0040] The sterilization temperature is 125℃ and the sterilization time is 2s. After sterilization, the liquid is cooled to 4~8℃ and put into sterile tank / ultra-clean tank.

[0041] The volume setting of the present invention does not use solution replenishment, and the function of the volume setting is only to determine the content of the concentrated milk.

[0042] (5) Filling: The sterile tank / ultra-clean tank is fed to the filling machine for filling.

[0043] The product prepared in this embodiment is whole milk, and the protein content in the whole milk is 6.2% and the fat content is 4.6%.

[0044] Example 2 Whole milk

[0045] The preparation method of whole milk in the present embodiment is as follows:

[0046] (1) Raw milk pretreatment: The raw milk is passed through a milk separator to purify and sterilize the raw milk, and then cooled to 6°C for later use;

[0047] (2) Preparation of skim milk: The raw milk prepared in step (1) is heated to 70°C and passed through a fat separator to obtain cream and skim milk. The skim milk is then cooled to 8°C and set aside.

[0048] (3) Skim milk concentration: The skim milk concentration method in this embodiment is the same as that in Example 1;

[0049] (4) INF sterilization: The concentrated milk after volume adjustment is backfilled with the corresponding light cream and then homogenized and sterilized. The homogenization conditions are 250 bar, the secondary homogenization pressure is 50 bar, and the homogenization temperature is 65 °C; the sterilization parameters are 133 °C, 0.5 s; after sterilization, the liquid is cooled to 4~8 °C and poured into aseptic tanks / ultra-clean tanks.

[0050] The volume setting of the present invention does not use solution replenishment, and the function of the volume setting is only to determine the content of the concentrated milk.

[0051] (5) Filling: The sterile tank / ultra-clean tank is fed to the filling machine for filling.

[0052] The product prepared in this embodiment is whole milk, and the protein content in the whole milk is 7.3% and the fat content is 4.6%.

[0053] Example 3 Skim milk

[0054] The preparation method of skim milk in the present embodiment is as follows:

[0055] (1) Raw milk pretreatment: The raw milk is passed through a milk separator to purify and sterilize the raw milk, and then cooled to 4°C for later use;

[0056] (2) Preparation of skim milk: The raw milk prepared in step (1) is heated to 50°C and passed through a fat separator to obtain cream and skim milk. The skim milk is then cooled to 4-8°C and set aside.

[0057] (3) Skim milk concentration: The skim milk concentration method in this embodiment is the same as that in Example 1;

[0058] (4) INF sterilization: homogenize the concentrated milk after volume adjustment at a homogenization condition of 235 bar, a secondary homogenization pressure of 45 bar, and a homogenization temperature of 60°C; sterilize after homogenization at a sterilization parameter of 128°C for 2 seconds; after sterilization, cool the liquid to 4-8°C and put it into an aseptic tank / ultra-clean tank;

[0059] (5) Filling: The sterile tank / ultra-clean tank is fed to the filling machine for filling.

[0060] The product prepared in this embodiment is skim milk, and the protein content in the skim milk is 6.2% and the fat content is 3.5%.

[0061] Example 4 Skim milk

[0062] The preparation method of skim milk in the present embodiment is as follows:

[0063] (1) Raw milk pretreatment: The raw milk is passed through a milk separator to purify and sterilize the raw milk, and then cooled to 6°C for later use;

[0064] (2) Preparation of skim milk: The raw milk prepared in step (1) is heated to 70°C and passed through a fat separator to obtain cream and skim milk. The skim milk is then cooled to 4-8°C and set aside.

[0065] (3) Skim milk concentration: The skim milk concentration method in this embodiment is the same as that in Example 1;

[0066] (4) INF sterilization: homogenize and sterilize the concentrated milk after volume adjustment; the homogenization conditions are 220 bar, the secondary homogenization pressure is 45 bar, and the homogenization temperature is 60 ° C; the sterilization parameters are 131 ° C, 0.5 s; after sterilization, the liquid is cooled to 4~8 ° C and put into aseptic tanks / ultra-clean tanks;

[0067] (5) Filling: The sterile tank / ultra-clean tank is fed to the filling machine for filling.

[0068] The product prepared in this embodiment is skim milk, and the protein content in the skim milk is 7.3% and the fat content is 3.5%.

[0069] Example 5

[0070] The difference between this embodiment and embodiment 4 is that, in step (3) of skim milk freeze concentration, the ice crystal mixture is dissolved and washed using the same pressure washing column as that used in the first-stage crystallizer after crystallization in the second-stage crystallizer.

[0071] Comparative Example 1 Different freeze concentration methods

[0072] This comparative example differs from Example 4 in that, in step (3) of freeze-concentrating the skim milk, the first stage of crystallization and concentration is omitted, i.e., the third stage crystallizer is no longer used, and the concentrate after treatment in the second stage crystallizer is used as the concentrated milk. The resulting product is skim milk, which has a protein content of 6.2% and a fat content of 3.5%.

[0073] Comparative Example 2 Different Sterilization Methods

[0074] The difference between this comparative example and Example 4 is that the MF filtration sterilization method is used in step (4).

[0075] The primary filtration pore size of the ceramic membrane used for MF filtration and sterilization is 0.45μm, the high-efficiency filtration pore size is 0.02μm, and the pressure is 1~2bar.

[0076] The prepared product is skim milk, which has a protein content of 7.3% and a fat content of 3.5%.

[0077] Comparative Example 3 Different INF sterilization parameters

[0078] The difference between this comparative example and Example 4 is that the INF sterilization parameter used in step (4) is: 142°C for 0.5s. The product prepared is skim milk, which has a protein content of 7.3% and a fat content of 3.5%.

[0079] Comparative Example 4 Different Sterilization Methods

[0080] The difference between this comparative example and Example 4 is that step (4) uses low-temperature plate pasteurization at 85°C for 15 seconds. The product prepared is skim milk, which has a protein content of 6.2% and a fat content of 3.5%.

[0081] Comparative Example 5 Different Concentration Methods

[0082] The difference between this comparative example and Example 4 is that: step (3) uses a conventional RO membrane concentration method; during INF sterilization in step (4), the cream is backfilled into the concentrated milk and then homogenized.

[0083] During RO membrane concentration, the flow rate used is 15,000 L / h, the pressure is 10-20 bar, and the concentration ratio is 1:1.3.

[0084] The prepared product is whole milk, which has a protein content of 5.3% and a fat content of 4.6%.

[0085] Comparative Example 6 Different Concentration Methods

[0086] The difference between this comparative example and Example 4 is that the flash concentration method is used in step (3). During the INF sterilization in step (4), the cream is backfilled into the concentrated milk and homogenized.

[0087] The temperature of flash concentration is 60~70℃, and the vacuum degree is -0.5~0.8bar.

[0088] The prepared product is whole milk, which has a protein content of 5.3% and a fat content of 4.6%.

[0089] Comparative Example 7 Milk with different fat contents obtained by RO membrane concentration

[0090] This comparative example differs from comparative example 5 in that partial fat-skimming is performed. That is, during the INF sterilization step (4), the concentrated milk after volume adjustment and part of the cream are backfilled and homogenized. The resulting product is skim milk, which has a protein content of 5.3% and a fat content of 3.5%.

[0091] Comparative Example 8 Milk with different fat contents obtained by flash evaporation and concentration

[0092] This comparative example differs from comparative example 6 in that it is partially skimmed, i.e., during the INF sterilization step (4), the condensed milk after volume adjustment and part of the cream are backfilled and homogenized. The resulting product is skimmed milk, which has a protein content of 5.3% and a fat content of 3.5%.

[0093] Experimental Example 1 Particle size, stability test, viscosity test

[0094] The particle size and stability of the products of the examples and comparative examples were tested respectively. The particle size was measured using a Beckman LS13320 laser diffraction particle size analyzer, the stability was measured using a LUM stability analyzer, and the viscosity was measured using an ANTON PAAR rheometer. The results are shown in Table 1.

[0095] Table 1 Particle size, stability and viscosity test results

[0096]

[0097] It can be seen from the test results in Table 1 that among Examples 1 to 4, the product of Example 4 has better particle size and stability clarity index, the lowest viscosity, and the best overall performance.

[0098] When tested on the 15th and 30th days under refrigerated conditions of 1-6°C and room temperature of 24-28°C, the products of Comparative Examples 1-8 all had varying degrees of fat floating.

[0099] Experimental Example 2 Consumer Taste Test

[0100] In this experimental example, a comprehensive score of 10 points was given to the frozen concentrated milk and the control ratio. 25 people were selected and the average score was taken. The results are shown in Table 2.

[0101] Table 2 Consumer taste test results

[0102]

[0103] As can be seen from Table 2, among Examples 1 to 5, Example 4 has the best performance in terms of frankincense, aftertaste and smoothness. From a comprehensive evaluation perspective, Example 4 has the highest comprehensive performance score.

[0104] Experimental Example 3: Nutritional Component Determination

[0105] In this experimental example, the immunoglobulin, lactoferrin, β-lactoglobulin, furosine and lactoperoxidase contents of the products obtained in the examples and comparative examples were determined. The results are shown in Table 3.

[0106] Table 3 Test results of active nutritional indicators

[0107]

[0108] As can be seen from Table 3, in Examples 1 to 5, the contents of immunoglobulin, lactoferrin, β-lactoglobulin, and lactoperoxidase are relatively high, and the level of glycine is relatively low.

[0109] The protein content of the milk products obtained in combination with the examples and comparative examples and the results in Tables 1 to 3 show that:

[0110] (1) From the perspective of concentration method: Concentrated milk obtained by other concentration methods cannot produce a high-nutrition milk product with good nutrition, taste and stability even if the INF sterilization method is used.

[0111] Specifically, when pasteurizing concentrated milk with a protein content exceeding 5% obtained through flash concentration or RO membrane concentration, the INF sterilization method was ineffective in producing either skim milk or whole milk. Compared with Example 4, the products obtained in Comparative Examples 5-8 exhibited low levels of active nutrient retention, including low levels of immunoglobulins, lactoferrin, β-lactoglobulin, and lactoperoxidase. This suggests, to some extent, that the processing techniques employed in Comparative Examples 5-8 resulted in partial denaturation of the nutrients in the milk after heat treatment.

[0112] In addition, the products of Comparative Examples 5 to 8 all have problems such as significantly increased particle size, high viscosity index, and poor stability. At the same time, the products of Comparative Examples 5 to 8 have insufficient frankincense, a strong cooking feeling, and insufficient aftertaste and smoothness.

[0113] (2) From the perspective of the sterilization method: Compared with the sterilization methods of Examples 1 to 5, the pasteurization method of Comparative Example 4 has the highest retention of active nutrients. In Comparative Example 4, sterilization at 85°C for 15 seconds well retains the nutritional components of the concentrated milk. However, the particle size of the product of Comparative Example 4 is significantly increased, and fat floats, indicating poor product stability. In addition, the milk flavor and aftertaste of the product obtained in Comparative Example 4 are insufficient. Therefore, traditional pasteurization methods are not suitable for sterilizing high-protein milk.

[0114] The present invention also provides an INF sterilization method with a sterilization temperature of 142°C and a sterilization time of 0.2-0.5 seconds. As shown in Comparative Example 3, the product obtained in Comparative Example 3 exhibits low nutrient retention and a significantly increased particle size. Furthermore, the product exhibits high viscosity, insufficient frankincense, a slightly stronger cooking sensation, and insufficient aftertaste and smoothness. In other words, even with freeze-concentration, the resulting concentrated milk, under the unsuitable INF sterilization method, still fails to achieve the desired taste and nutritional value of high-quality nutritious milk.

[0115] (3) From the perspective of freeze concentration methods: Different freeze concentration methods are suitable for different sterilization methods. The most suitable sterilization method for the concentrated milk obtained by the three-stage freeze crystallization provided by the present invention is INF sterilization, with a sterilization temperature of 125-133°C and a sterilization time of 0.5-2 seconds.

[0116] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for preparing high-nutrient milk, characterized in that: include: The raw milk and milk fat are separated to obtain skim milk and cream, the skim milk is freeze-concentrated by a three-stage crystallizer to obtain concentrated milk, and the concentrated milk is homogenized and sterilized by INF; The sterilization temperature is 125-133°C, and the sterilization time is 0.5-2s, to obtain the high-multiple nutritional milk; the protein content of the high-multiple nutritional milk is greater than 6%; in the freeze concentration, the ice crystal mixture generated by the first-stage crystallizer is washed by a pressure washing column to obtain a lower layer concentrate; the ice crystal mixture generated by the second-stage crystallizer is washed by a solution through a pressure-free secondary washing column to obtain a skim milk concentrate; The skim milk concentrate is crystallized in a third-stage crystallizer and ice crystals are filtered to obtain concentrated milk.

2. The preparation method according to claim 1, characterized in that: The method of homogenizing and sterilizing the concentrated milk in INF is replaced by backfilling the concentrated milk with the cream and then homogenizing and sterilizing it in INF.

3. The preparation method according to claim 1, characterized in that: The INF sterilization temperature is 128~131℃ and the sterilization time is 0.5~2s.

4. The preparation method according to claim 1 or 3, characterized in that: include: (1) Raw milk pretreatment: Purify and sterilize the raw milk, cool it to 4-6°C and set it aside; (2) Preparation of skim milk: The raw milk prepared in step (1) is heated to 50-70°C and passed through a fat separator to obtain cream and skim milk. The skim milk is cooled to 4-8°C and set aside. (3) Freeze-concentrating skim milk: passing the skim milk obtained in step (2) through a three-stage crystallizer, filtering the obtained ice crystal mixture, and obtaining concentrated milk; (4) INF sterilization: the concentrated milk obtained in step (3) is homogenized and sterilized by INF; The sterilized liquid is cooled to 4-8° C. to obtain the high-multiple nutritious milk.

5. The preparation method according to claim 2, characterized in that: include: (1) Raw milk pretreatment: Purify and sterilize the raw milk, cool it to 4-6°C and set it aside; (2) Preparation of skim milk: The raw milk prepared in step (1) is heated to 50-70°C and passed through a fat separator to obtain cream and skim milk. The skim milk is cooled to 4-8°C and set aside. (3) Freeze-concentrating skim milk: passing the skim milk obtained in step (2) through a three-stage crystallizer, filtering the obtained ice crystal mixture, and obtaining concentrated milk; (4) INF sterilization: backfilling the concentrated milk obtained in step (3) with cream for homogenization and INF sterilization; The sterilized liquid is cooled to 4-8° C. to obtain the high-multiple nutritious milk.

6. The preparation method according to claim 1, characterized in that: The homogenization conditions are 220-250 bar, the secondary homogenization pressure is 40-50 bar, and the homogenization temperature is 55-65°C.

7. The preparation method according to claim 6, characterized in that: The pressure of the pressure washing column used after crystallization in the first stage crystallizer is 1~2 bar.

8. The preparation method according to claim 7, characterized in that: The size of the spherical crystals generated in the crystallizer is between 0.2 and 1 mm; in the first-stage crystallizer, the gap between the ice crystal beds is 35 to 45%; in the second-stage crystallizer, the gap between the ice crystal beds is 50 to 55%.

9. A high-nutrient milk, characterized in that: The high-nutrient milk is prepared by the preparation method according to any one of claims 1 to 8.

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