Method for improving stability of fermented milk system

Abstract

The invention provides a method for improving the stability of a fermented milk system. Specifically, the method comprises the following steps: carrying out the following treatment on raw milk to obtain a fermented milk raw material: (1) carrying out ultrasonic treatment on the raw milk to obtain an ultrasonic treatment substance; (2) adding dietary fibers into the ultrasonic treatment material to obtain a mixed material; (3) performing microwave treatment on the mixed material to obtain a microwave treated material; and (4) adding an ionic stabilizer into the microwave treated material to obtain the fermented milk raw material. The method is beneficial to establishment of a good product texture, the yoghourt prepared on the basis is fine and smooth in taste, pleasant in flavor and good in texture, the requirements of consumers can be met, and the taste and stability of the product can be improved on the premise of maintaining nutrition.

Description

Technical Field

[0001] The invention relates to the field of fermented milk product production, and in particular to a method for improving the stability of a fermented milk system. Background Art

[0002] Current research has found that yogurt texture is affected by a variety of factors, among which heat treatment and bacterial species have a direct impact on the quality of texture. In actual industrial production, most companies usually use additives to make yogurt meet certain texture standards, mainly including gelatin, pectin, sodium carboxymethyl cellulose and diacetyl tartaric acid mono- and diglycerides, etc. However, with the improvement of consumers' health awareness, the use of additives has a negative impact on product sales. There is currently little research on improving product texture by combining the addition of dietary fiber with process optimization. Summary of the invention

[0003] One object of the present invention is to provide a method for improving the stability of a fermented milk system. The method is conducive to establishing a good product texture. The yogurt prepared on this basis has a delicate taste, pleasant flavor, good texture, can meet consumer needs, and can improve the taste and stability of the product while maintaining nutrition.

[0004] Specifically, in a first aspect, the present invention provides a method for improving the stability of a fermented milk system, comprising the steps of subjecting raw milk to the following treatment to obtain a fermented milk raw material:

[0005] (1) subjecting the raw milk to ultrasonic treatment to obtain an ultrasonically treated product;

[0006] (2) adding dietary fiber to the ultrasonically treated product to obtain a mixed material;

[0007] (3) subjecting the mixed material to microwave treatment to obtain a microwave-treated material;

[0008] (4) adding an ionic stabilizer to the microwave-treated product to obtain the fermented milk raw material.

[0009] In a second aspect, the present application provides a method for preparing fermented milk, comprising the following steps:

[0010] (I) subjecting raw milk to the following treatments to obtain fermented milk raw material:

[0011] (1) subjecting the raw milk to ultrasonic treatment to obtain an ultrasonically treated product;

[0012] (2) adding dietary fiber to the ultrasonically treated product to obtain a mixed material;

[0013] (3) subjecting the mixed material to microwave treatment to obtain a microwave-treated material;

[0014] (4) adding an ionic stabilizer to the microwave-treated product to obtain the fermented milk raw material;

[0015] (II) performing one or more of the following operations on the fermented milk raw material: degassing, homogenization, sterilization, fermentation, post-ripening and canning to obtain the fermented milk.

[0016] In the first aspect or the second aspect above, the method is characterized by one or more of the following:

[0017] 1) The power of the ultrasound is 400-600W, for example 400W, 450W, 500W, 550W or 600W;

[0018] 2) ultrasonically treating the raw milk for 1 min to 30 min, for example, 1 min, 5 min, 10 min, 15 min, 20 min, 25 min or 30 min;

[0019] 3) The dietary fiber is polydextrose or resistant dextrin;

[0020] 4) the dietary fiber is added in an amount of 5wt%-10wt%, such as 5wt%, 6wt%, 7wt%, 8wt%, 9wt% or 10wt%;

[0021] 5) The power of the microwave is 300-600 W, for example, 300 W, 350 W, 400 W, 450 W, 500 W, 550 W or 600 W;

[0022] 6) subjecting the mixture to microwave treatment for 1 min to 30 min, for example, 1 min, 5 min, 10 min, 15 min, 20 min, 25 min or 30 min;

[0023] 7) The ionic stabilizer is a cationic stabilizer, such as a sodium ion, potassium ion or magnesium ion stabilizer, and the ionic stabilizer is preferably sodium chloride or potassium chloride;

[0024] 8) Calculated according to the cation concentration, the amount of the ionic stabilizer added is 10mmol / L-20mmol / L, for example, 10mmol / L, 12mmol / L, 14mmol / L, 16mmol / L, 18mmol / L or 20mmol / L;

[0025] 9) After adding the ionic stabilizer, a hydration step is further included, for example, hydration at 50-80° C. for 10-60 min, and for example, hydration at 60-70° C. for 20-30 min.

[0026] In the first aspect or the second aspect above, the method is characterized in that:

[0027] The fermented dairy product is yogurt or a fermented beverage; and / or

[0028] The raw milk is fresh animal milk, reconstituted animal milk or animal milk powder. Preferably, the animal is selected from cattle, sheep, camels, yaks and horses. Preferably, the animal milk raw material is fresh milk, reconstituted milk or milk powder.

[0029] In the first aspect, the method further comprises performing one or more of the following operations on the fermented milk raw material: degassing, homogenization, sterilization, fermentation, post-ripening and canning.

[0030] In the first aspect or the second aspect above, the method is characterized by one or more of the following:

[0031] i) The ultrasonic treatment conditions are: 400-600W, ultrasonic treatment for 5-10min;

[0032] ii) the microwave treatment conditions are: 300-500W, continuous treatment for 5-10min;

[0033] iii) the degassing pressure is 18-20 MPa, and the degassing temperature is 60-70° C.;

[0034] iv) the sterilization temperature is 93-95°C and the sterilization time is 280-300s;

[0035] v) the homogenization pressure is 200-220 bar;

[0036] vi) the mass of the fermentation agent used is 100U-200U / t;

[0037] vii) the fermentation temperature is 40-43°C, and the fermentation is carried out until the acidity reaches 78-82°T;

[0038] viii) The fermentation agent is one probiotic or a combination of multiple probiotics, and the probiotics are preferably one or a combination of two or more of Streptococcus thermophilus, Lactobacillus bulgaricus, Lactobacillus acidophilus, and Lactobacillus rhamnosus.

[0039] In some embodiments, the base temperature is cooled to 40-45°C before adding the leavening agent.

[0040] In the above preparation method, the raw milk refers to fresh milk that meets the fresh milk purchase standard GB6914 of my country, and can be a combination of one or more of skim milk or partially skim milk. In a specific embodiment, the milk can be fresh milk, or it can be a reduced product made by reducing milk powder, condensed milk or whey protein. The starter can adopt a combination of one probiotic or multiple probiotics, preferably a combination of one or more of thermophilic Streptococcus, Bulgarian Lactobacillus, Lactobacillus acidophilus, and Lactobacillus rhamnosus. The packaging form of the fermented milk product prepared by the method of the present invention can adopt the packaging form of yogurt commonly found on the market, such as glass bottle packaging, cup packaging, etc. The processes not specifically mentioned in the preparation method of the present invention, such as batching, degassing, homogenization, sterilization, and other more specific operations and the equipment used can all adopt conventional equipment in the field.

[0041] In a third aspect, the present application provides a fermented dairy product, which is prepared by the method described in any one of the second aspects.

[0042] In some embodiments, the fermented dairy product is yogurt or a fermented beverage.

[0043] In some embodiments, the fermented dairy product is yogurt. In some embodiments, the yogurt has a viscosity of >1000 mPa·s, such as >1050 mPa·s, such as >1100 mPa·s, such as >1150 mPa·s.

[0044] In some embodiments, the yogurt has a water holding capacity of >60%, such as >65%, such as >70%, such as >75%, such as >80%, such as >85%.

[0045] In some embodiments, the yogurt has a refrigerated viable count of >1×10 8 CFU / g, for example, >2×10 8 CFU / g,>3×10 8 CFU / g,>4×10 8 CFU / g,>5×10 8 CFU / g,>6×10 8 CFU / g,>7×10 8 CFU / g,>8×10 8 CFU / g or >9×10 8 CFU / g.

[0046] Advantageous Effects of the Invention

[0047] The present invention first physically modifies milk protein by ultrasonic treatment, and then uses microwaves to continue to treat pretreated milk containing dietary fiber, so that the dietary fiber is tightly filled in the network system of milk protein, and then cationic components are added to promote the protein network system filled with dietary fiber to be more stable, so that the protein pores tend to be dense and uniform. The method of the present invention is conducive to establishing a good product texture. The yogurt prepared on this basis has a delicate taste, pleasant flavor, good texture, can meet consumer needs, and can improve the taste and stability of the product while maintaining nutrition. DETAILED DESCRIPTION

[0048] The embodiments of the present invention will be described in detail below in conjunction with the examples, but those skilled in the art will appreciate that the following examples are only used to illustrate the present invention and should not be considered to limit the scope of the present invention. If no specific conditions are specified in the examples, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0049] Example 1

[0050] This embodiment provides a method for preparing fermented milk, which includes two processes: fermented milk base processing and fermented milk preparation, and specifically includes the following steps:

[0051] 1. Fermented milk-based treatment

[0052] (1) Ultrasonic treatment: The milk was treated continuously at an ultrasonic power of 600 W for 10 min (working time 1 s, rest time 1 s);

[0053] (2) Mixing: Add 10 g of resistant dextrin to the milk after ultrasonic treatment and mix well;

[0054] (3) Microwave modification treatment: The mixed milk was subjected to microwave modification treatment at 500 W for 10 min;

[0055] (4) Cationic strengthening treatment: Add 20 mmol / L sodium chloride to the microwave-modified milk and let it stand at 65°C for 30 min to hydrate.

[0056] 2. Fermented milk preparation

[0057] (1) Degassing, homogenization, and sterilization: degassing pressure 20 MPa, temperature 70°C, homogenization pressure 180 bar, homogenization temperature 95°C, time 300 s;

[0058] (2) Fermentation: Cool the milk base to 40-45°C, add 200U / t starter, stir evenly, and ferment at 43°C until the acidity reaches above 70°T;

[0059] (3) Post-ripening: The fermented product is placed at 4°C for 12 hours.

[0060] Example 2

[0061] This embodiment provides a method for preparing fermented milk, which includes two processes: fermented milk base processing and fermented milk preparation, and specifically includes the following steps:

[0062] 1. Fermented milk-based treatment

[0063] (1) Ultrasonic treatment: The milk was treated continuously at an ultrasonic power of 400 W for 10 min (working time 1 s, rest time 1 s);

[0064] (2) Mixing: Add 10 g of resistant dextrin to the milk after ultrasonic treatment and mix well;

[0065] (3) Microwave modification treatment: The mixed milk was subjected to microwave modification treatment at 500 W for 10 min;

[0066] (4) Cationic strengthening treatment: Add 20 mmol / L sodium chloride to the microwave-modified milk and let it stand at 65°C for 30 min to hydrate.

[0067] 2. Fermented milk preparation

[0068] Same as Example 1.

[0069] Example 3

[0070] 1. Fermented milk-based treatment

[0071] (1) Ultrasonic treatment: The milk was treated continuously at an ultrasonic power of 600 W for 10 min (working time 1 s, rest time 1 s);

[0072] (2) Mixing: Add 10 g of resistant dextrin to the milk after ultrasonic treatment and mix well;

[0073] (3) Microwave modification treatment: The mixed milk was subjected to microwave modification treatment at 300 W for 10 min;

[0074] (4) Cationic strengthening treatment: Add 20 mmol / L sodium chloride to the microwave-modified milk and let it stand at 65°C for 30 min to hydrate.

[0075] 2. Fermented milk preparation

[0076] Same as Example 1.

[0077] Example 4

[0078] 1. Fermented milk-based treatment

[0079] (1) Ultrasonic treatment: The milk was treated continuously at an ultrasonic power of 400 W for 10 min (working time 1 s, rest time 1 s);

[0080] (2) Mixing: Add 10 g of resistant dextrin to the milk after ultrasonic treatment and mix well;

[0081] (3) Microwave modification treatment: The mixed milk was subjected to microwave modification treatment at 300 W for 10 min;

[0082] (4) Cationic strengthening treatment: Add 20 mmol / L sodium chloride to the microwave-modified milk and let it stand at 65°C for 30 min to hydrate.

[0083] 2. Fermented milk preparation

[0084] Same as Example 1.

[0085] Example 5

[0086] 1. Fermented milk-based treatment

[0087] (1) Ultrasonic treatment: The milk was treated continuously at an ultrasonic power of 600 W for 10 min (working time 1 s, rest time 1 s);

[0088] (2) Mixing: Add 5 g of resistant dextrin to the milk after ultrasonic treatment and mix well;

[0089] (3) Microwave modification treatment: The mixed milk was subjected to microwave modification treatment at 300 W for 50 min;

[0090] (4) Cationic strengthening treatment: Add 15 mmol / L sodium chloride to the microwave-modified milk and let it stand at 65°C for 30 min to hydrate.

[0091] 2. Fermented milk preparation

[0092] Same as Example 1.

[0093] Example 6

[0094] 1. Fermented milk-based treatment

[0095] (1) Ultrasonic treatment: The milk was treated continuously at an ultrasonic power of 600 W for 10 min (working time 1 s, rest time 1 s);

[0096] (2) Mixing: Add 10 g of resistant dextrin to the milk after ultrasonic treatment and mix well;

[0097] (3) Microwave modification treatment: The mixed milk was subjected to microwave modification treatment at 300 W for 50 min;

[0098] (4) Cationic strengthening treatment: Add 10 mmol / L sodium chloride to the microwave-modified milk and let it stand at 65°C for 30 min to hydrate.

[0099] 2. Fermented milk preparation

[0100] Same as Example 1.

[0101] Comparative Example 1

[0102] 1. Fermented milk-based treatment

[0103] (1) Ultrasonic treatment: The milk was treated continuously at an ultrasonic power of 300 W for 10 min (working time 1 s, rest time 1 s);

[0104] (2) Mixing: Add 10 g of resistant dextrin to the milk after ultrasonic treatment and mix well;

[0105] (3) Microwave modification treatment: The mixed milk was subjected to microwave modification treatment at 500 W for 50 min;

[0106] (4) Cationic strengthening treatment: Add 20 mmol / L sodium chloride to the microwave-modified milk and let it stand at 65°C for 30 min to hydrate.

[0107] 2. Fermented milk preparation

[0108] Same as Example 1.

[0109] Comparative Example 2

[0110] 1. Fermented milk-based treatment

[0111] (1) Ultrasonic treatment: The milk was treated continuously at an ultrasonic power of 700 W for 10 min (working time 1 s, rest time 1 s);

[0112] (2) Mixing: Add 10 g of resistant dextrin to the milk after ultrasonic treatment and mix well;

[0113] (3) Microwave modification treatment: The mixed milk was subjected to microwave modification treatment at 500 W for 50 min;

[0114] (4) Cationic strengthening treatment: Add 20 mmol / L sodium chloride to the microwave-modified milk and let it stand at 65°C for 30 min to hydrate.

[0115] 2. Fermented milk preparation

[0116] Same as Example 1.

[0117] Comparative Example 3

[0118] 1. Fermented milk-based treatment

[0119] (1) Ultrasonic treatment: The milk was treated continuously at an ultrasonic power of 600 W for 10 min (working time 1 s, rest time 1 s);

[0120] (2) Mixing: Add 10 g of resistant dextrin to the milk after ultrasonic treatment and mix well;

[0121] (3) Microwave modification treatment: The mixed milk was subjected to microwave modification treatment at 200 W for 50 min;

[0122] (4) Cationic strengthening treatment: Add 20 mmol / L sodium chloride to the microwave-modified milk and let it stand at 65°C for 30 min to hydrate.

[0123] 2. Fermented milk preparation

[0124] Same as Example 1.

[0125] Comparative Example 4

[0126] 1. Fermented milk-based treatment

[0127] (1) Ultrasonic treatment: The milk was treated continuously at an ultrasonic power of 600 W for 10 min (working time 1 s, rest time 1 s);

[0128] (2) Mixing: Add 10 g of resistant dextrin to the milk after ultrasonic treatment and mix well;

[0129] (3) Microwave modification treatment: The mixed milk was subjected to microwave modification treatment at 600 W for 50 min;

[0130] (4) Cationic strengthening treatment: Add 20 mmol / L sodium chloride to the microwave-modified milk and let it stand at 65°C for 30 min to hydrate.

[0131] 2. Fermented milk preparation

[0132] Same as Example 1.

[0133] Comparative Example 5

[0134] 1. Fermented milk-based treatment

[0135] (1) Ultrasonic treatment: The milk was treated continuously at an ultrasonic power of 600 W for 10 min (working time 1 s, rest time 1 s);

[0136] (2) Mixing: Add 4 g of resistant dextrin to the milk after ultrasonic treatment and mix well;

[0137] (3) Microwave modification treatment: The mixed milk was subjected to microwave modification treatment at 500 W for 50 min;

[0138] (4) Cationic strengthening treatment: Add 20 mmol / L sodium chloride to the microwave-modified milk and let it stand at 65°C for 30 min to hydrate.

[0139] 2. Fermented milk preparation

[0140] Same as Example 1.

[0141] Comparative Example 6

[0142] 1. Fermented milk-based treatment

[0143] (1) Ultrasonic treatment: The milk was treated continuously at an ultrasonic power of 600 W for 10 min (working time 1 s, rest time 1 s);

[0144] (2) Mixing: Add 12 g of resistant dextrin to the milk after ultrasonic treatment and mix well;

[0145] (3) Microwave modification treatment: The mixed milk was subjected to microwave modification treatment at 500 W for 50 min;

[0146] (4) Cationic strengthening treatment: Add 20 mmol / L sodium chloride to the microwave-modified milk and let it stand at 65°C for 30 min to hydrate.

[0147] 2. Fermented milk preparation

[0148] Same as Example 1.

[0149] Comparative Example 7

[0150] 1. Fermented milk-based treatment

[0151] (1) Ultrasonic treatment: The milk was treated continuously at an ultrasonic power of 600 W for 10 min (working time 1 s, rest time 1 s);

[0152] (2) Mixing: Add 10 g of resistant dextrin to the milk after ultrasonic treatment and mix well;

[0153] (3) Microwave modification treatment: The mixed milk was subjected to microwave modification treatment at 500 W for 50 min;

[0154] (4) Cationic strengthening treatment: Add 8 mmol / L sodium chloride to the microwave-modified milk and let it stand at 65°C for 30 min for hydration.

[0155] 2. Fermented milk preparation

[0156] Same as Example 1.

[0157] Comparative Example 8

[0158] 1. Fermented milk-based treatment

[0159] (1) Ultrasonic treatment: The milk was treated continuously at an ultrasonic power of 600 W for 10 min (working time 1 s, rest time 1 s);

[0160] (2) Mixing: Add 10 g of resistant dextrin to the milk after ultrasonic treatment and mix well;

[0161] (3) Microwave modification treatment: The mixed milk was subjected to microwave modification treatment at 500 W for 50 min;

[0162] (4) Cationic strengthening treatment: Add 12 mmol / L sodium chloride to the microwave-modified milk and let it stand at 65°C for 30 min to hydrate.

[0163] 2. Fermented milk preparation

[0164] Same as Example 1.

[0165] Test Example 1

[0166] The fermented milks prepared in Examples 1-6 and Comparative Examples 1-8 were subjected to sensory evaluation in terms of taste and flavor. The main evaluation items included: tissue state (whey separation, fat floating, viscosity, fineness, texture, etc.), color, flavor (including fat taste), mouthfeel, etc. A total of 30 people participated in the experiment, and sensory evaluation was performed on the yogurt products of Examples 1-6 and Comparative Examples 1-8.

[0167] The sensory scoring criteria are shown in Table 1, and the experimental record results are summarized in Table 2.

[0168]

[0169]

[0170] From the results in Table 2, it can be seen that the flavored fermented milk of Examples 1-6 has good texture, taste and flavor, no whey precipitation, rich characteristic flavor, harmonious aroma, strong taste, delicate taste, moderate sourness and sweetness, and uniform taste.

[0171] Comparing all the examples with the comparative examples, it can be seen that the following factors may affect the sensory evaluation of the product:

[0172] 1. Ultrasonic power: Through the analysis of Examples 1 and 2 and Comparative Examples 1 and 2, it was found that when the ultrasonic power was too low (<400 W), whey still precipitated from the product and the fermentation texture had obvious granularity. In addition, too high ultrasonic power would affect the product texture.

[0173] 2. Microwave treatment power: Through the analysis of Examples 1 and 3 and Comparative Examples 6 and 7, it was found that when the microwave power was too low (<300 W), whey still precipitated from the product and there was a slight granular feel, while when the microwave power was too high (>500 W), the flavor was not harmonious.

[0174] 3. Dietary fiber addition amount: Through the analysis of Example 1 and Comparative Examples 5 and 6, too low an addition amount has no obvious effect on improving the product texture, while too high an addition amount (≥10g / 100g) has a certain negative impact on the aroma and taste of the product.

[0175] 4. Adding cations to improve product texture: According to the analysis of Example 1 and Comparative Examples 7 and 8, excessively high cation concentration (≥20 mmoL / L) may inhibit fermentation efficiency and lead to poor product quality.

[0176] Test Example 2

[0177] For the carbonated fermented milk prepared in Examples 3 and 4 and Comparative Examples 5 and 6, the water holding capacity was measured by centrifugation, and the viscosity of the product was measured. Specific test results are shown in Table 3.

[0178] Table 3 Viscosity test results

[0179]

[0180]

[0181] From the results in Table 3, it can be seen that the water holding capacity of all the embodiments is significantly higher than that of all the comparative examples. On the one hand, it shows that appropriate ultrasonic treatment and microwave treatment are helpful to improve the product texture, and on the other hand, it shows that adding a certain amount of dietary fiber and sodium and potassium cations can significantly improve the product texture.

[0182] Test Example 3

[0183] Live bacteria counts were performed on the embodiments and comparative examples during the refrigerated shelf life to verify the impact of the method on product quality.

[0184] Table 4 Live bacteria counts during refrigerated shelf life

[0185] Sample code Viable bacteria count at 28 days (CFU / g) Example 1 5.8×10^8 Example 2 7.8×10^8 Example 3 6.9×10^8 Example 4 6.2×10^8 Example 5 7.6×10^8 Example 6 5.8×10^8 Comparative Example 1 6.7×10^8 Comparative Example 2 7.7×10^8 Comparative Example 3 5.2×10^8 Comparative Example 4 8.9×10^6 Comparative Example 5 7.9×10^8 Comparative Example 6 4.4×10^8 Comparative Example 7 3.2×10^8 Comparative Example 8 8.9×10^5

[0186] From the results in Table 4, it can be seen that except for Comparative Examples 4 and 8, the viable counts of the products in the other embodiments and comparative examples are all above 10 8 The above reasons are considered to be due to excessive addition of cations and excessively strong microwave modification treatment, which will affect the fermentation of live bacteria in the product.

[0187] Although the specific embodiments of the present invention have been described in detail, it will be understood by those skilled in the art that various modifications and substitutions may be made to those details based on all the teachings disclosed, and these changes are within the scope of protection of the present invention. The full scope of the present invention is given by the attached claims and any equivalents thereof.

Claims

1. A method for improving the stability of a fermented milk system, comprising the step of obtaining a fermented milk raw material by subjecting raw milk to the following treatments: (1) Ultrasonically treating the raw milk to obtain an ultrasonically treated product; (2) Adding dietary fiber to the ultrasonically treated product to obtain a mixture; (3) Microwaving the mixture to obtain a microwave-treated product; (4) Adding an ionic stabilizer to the microwave-treated product to obtain the fermented milk raw material.

2. The method according to claim 1, characterized in that one or more of the following: 1) The power of the ultrasound is 400 - 600 W, such as 400 W, 450 W, 500 W, 550 W or 600 W; 2) Ultrasonically treating the raw milk for 1 min - 30 min, such as 1 min, 5 min, 10 min, 15 min, 20 min, 25 min or 30 min; 3) The dietary fiber is polydextrose or resistant dextrin; 4) The addition amount of the dietary fiber is 5 wt% - 10 wt%, such as 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt% or 10 wt%; 5) The power of the microwave is 300 - 600 W, such as 300 W, 350 W, 400 W, 450 W, 500 W, 550 W or 600 W; 6) Microwaving the mixture for 1 min - 30 min, such as 1 min, 5 min, 10 min, 15 min, 20 min, 25 min or 30 min; 7) The ionic stabilizer is a cationic stabilizer, such as a sodium ion, potassium ion or magnesium ion stabilizer, and the ionic stabilizer is preferably sodium chloride or potassium chloride; 8) Calculated by cation concentration, the addition amount of the ionic stabilizer is 10 mmol / L - 20 mmol / L, such as 10 mmol / L, 12 mmol / L, 14 mmol / L, 16 mmol / L, 18 mmol / L or 20 mmol / L; 9) After adding the ionic stabilizer, it further includes a hydration step, such as hydrating at 50 - 80 °C for 10 - 60 min, or hydrating at 60 - 70 °C for 20 - 30 min.

3. The method according to claim 1 or 2, characterized in that: The fermented dairy product is yogurt or a fermented beverage; and / or The raw milk is fresh animal milk, reconstituted animal milk or animal milk powder. Preferably, the animal is selected from cows, sheep, camels, yaks and horses. Preferably, the animal milk raw material is fresh milk, reconstituted milk or milk powder.

4. The method according to any one of claims 1 - 3, further comprising performing one or more of the following operations on the fermented milk raw material: degassing, homogenization, sterilization, fermentation, post-ripening and canning.

5. A method for preparing fermented milk, comprising the following steps: (I) Obtaining a fermented milk raw material by subjecting raw milk to the following treatments: (1) Ultrasonically treating the raw milk to obtain an ultrasonically treated product; (2) Adding dietary fiber to the ultrasonically treated product to obtain a mixture; (3) Microwaving the mixture to obtain a microwave-treated product; (4) Adding an ionic stabilizer to the microwave-treated product to obtain the fermented milk raw material; (II) Perform one or more of the following operations on the fermented milk raw material: degassing, homogenization, sterilization, fermentation, ripening, and canning to obtain the fermented milk.

6. The method according to claim 5, characterized in that one or more of the following: 1) The power of the ultrasound is 400 - 600 W, such as 400 W, 450 W, 500 W, 550 W, or 600 W; 2) The raw milk is ultrasonically treated for 1 min - 30 min, such as 1 min, 5 min, 10 min, 15 min, 20 min, 25 min, or 30 min; 3) The dietary fiber is polydextrose or resistant dextrin; 4) The addition amount of the dietary fiber is 5 wt% - 10 wt%, such as 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, or 10 wt%; 5) The power of the microwave is 300 - 600 W, such as 300 W, 350 W, 400 W, 450 W, 500 W, 550 W, or 600 W; 6) The mixture is microwave-treated for 1 min - 30 min, such as 1 min, 5 min, 10 min, 15 min, 20 min, 25 min, or 30 min; 7) The ionic stabilizer is a cationic stabilizer, such as a sodium ion, potassium ion, or magnesium ion stabilizer, and the ionic stabilizer is preferably sodium chloride or potassium chloride; 8) Calculated by cation concentration, the addition amount of the ionic stabilizer is 10 mmol / L - 20 mmol / L, such as 10 mmol / L, 12 mmol / L, 14 mmol / L, 16 mmol / L, 18 mmol / L, or 20 mmol / L; 9) After adding the ionic stabilizer, a hydration step is further included, such as hydrating at 50 - 80 °C for 10 - 60 min, or further such as hydrating at 60 - 70 °C for 20 - 30 min.

7. The method according to claim 5 or 6, characterized in that: The fermented dairy product is yogurt or a fermented beverage; and / or The raw milk is fresh animal milk, reconstituted animal milk, or animal milk powder. Preferably, the animal is selected from cows, sheep, camels, yaks, and horses. Preferably, the animal milk raw material is fresh milk, reconstituted milk, or milk powder.

8. A fermented dairy product prepared by the method according to any one of claims 5 - 7; Preferably, the fermented dairy product is yogurt or a fermented beverage.

9. The fermented dairy product according to claim 8, which is yogurt; Preferably, the viscosity of the yogurt > 1000 mPa·s, such as > 1050 mPa·s, such as > 1100 mPa·s, such as > 1150 mPa·s; Preferably, the water holding capacity of the yogurt > 60%, such as > 65%, such as > 70%, such as > 75%, such as > 80%, such as > 85%; Preferably, the viable count of live bacteria in the refrigerated yogurt during the shelf life (e.g., within 7 days, within 14 days, or within 28 days) > 1×10 8 CFU / g, for example > 2×10 8 CFU / g, > 3×10 8 CFU / g, > 4×10 8 CFU / g, > 5×10 8 CFU / g, > 6×10 8 CFU / g, > 7×10 8 CFU / g, > 8×10 8 CFU / g or > 9×10 8 CFU / g.

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