Bifidobacterium longum fermented milk and method for preparing the same

Abstract

This invention relates to the field of dairy products, and in particular to a Bifidobacterium longum fermented milk and its preparation method. The invention provides a method for preparing Bifidobacterium longum fermented milk, comprising: providing a Bifidobacterium longum growth promoter, wherein the Bifidobacterium longum growth promoter comprises a slurry of cooked red beans and pineapple pulp; mixing the Bifidobacterium longum growth promoter with milk to provide a fermentation system; inoculating the fermentation system with Bifidobacterium longum; and fermenting. The method for preparing Bifidobacterium longum fermented milk provided by this invention, and the resulting Bifidobacterium longum fermented milk, have advantages over other similar products, including natural edibility, good taste, and low cost. Furthermore, it is a pure fermentation process, free from contamination by other microorganisms, and the resulting fermented milk has a long shelf life, thus effectively solving the problems existing in other similar products in the prior art, and has good industrialization prospects.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of dairy products, in particular to a Bifidobacterium longum fermented milk and a preparation method thereof. BACKGROUND

[0002] Bifidobacterium is the dominant bacteria in the intestinal tract of healthy human body, which has the functions of antagonizing pathogenic bacteria, regulating intestinal flora, synthesizing various vitamins, reducing cholesterol, preventing cancer, enhancing immunity and the like. At present, probiotic health care products containing Bifidobacterium have been widely used at home and abroad, and are deeply welcomed by consumers. However, Bifidobacterium is usually difficult to grow and reproduce in milk. Although Bifidobacterium fermented milk has been developed from different technical perspectives at home and abroad, some of these products have complex components and high cost, some are made of non-natural edible materials and have poor taste, some are mixed fermentation and non-pure Bifidobacterium products, some have poor survival activity, short shelf life and are difficult to be marketed. Moreover, most of the existing Bifidobacterium fermented milk ignores the detection of bacterial contamination, and the true content of Bifidobacterium is difficult to guarantee. SUMMARY

[0003] In view of the above-mentioned shortcomings of the prior art, the purpose of the present application is to provide a Bifidobacterium longum fermented milk and a preparation method thereof, which can solve the problems in the prior art.

[0004] To achieve the above-mentioned purposes and other related purposes, one aspect of the present application provides a preparation method of Bifidobacterium longum fermented milk, comprising:

[0005] 1) providing a Bifidobacterium longum proliferation agent, wherein the Bifidobacterium longum proliferation agent comprises a slurry of cooked red beans and pineapple flesh;

[0006] 2) mixing the Bifidobacterium longum proliferation agent provided in step 1) with milk to provide a fermentation system;

[0007] 3) inoculating Bifidobacterium longum into the fermentation system provided in step 2) and performing fermentation treatment.

[0008] In some embodiments of the present application, the Bifidobacterium longum proliferation agent comprises, based on 100 parts by weight:

[0009] 2-20 parts of red beans;

[0010] 5-30 parts of pineapple flesh.

[0011] In some embodiments of the present application, the preparation method of the Bifidobacterium longum proliferation agent comprises homogenizing and mixing cooked red beans and pineapple flesh, and preferably further comprises solid-liquid separation and / or sterilization.

[0012] In some embodiments of the present application, in step 2), the content of the Bifidobacterium longum proliferation agent in the fermentation system is 3-30 wt%.

[0013] In some embodiments of the present application, in step 2), the milk is selected from the group consisting of raw milk, liquid milk, reconstituted milk, one or more combinations thereof.

[0014] In some embodiments of the present application, in step 2), the fermentation system further comprises an additive selected from the group consisting of a flavoring agent, an acid-base stabilizer, a thickening agent, one or more combinations thereof.

[0015] In some embodiments of the present application, in step 3), the Bifidobacterium longum is Bifidobacterium longum BL-05.

[0016] In some embodiments of the present application, in step 3), the inoculation concentration of Bifidobacterium longum in the fermentation system is 0.1-200 x 10 6 CFU / g.

[0017] In some embodiments of the present application, in step 3), the fermentation temperature of the fermentation treatment is 36-38℃.

[0018] In some embodiments of the present application, in step 3), the fermentation time of the fermentation treatment is 10-20h.

[0019] In some embodiments of the present application, in step 3), the fermentation treatment is a static fermentation treatment.

[0020] Another aspect of the present application provides a Bifidobacterium longum fermented milk prepared by the above-mentioned method for preparing a Bifidobacterium longum fermented milk. DETAILED DESCRIPTION

[0021] In order to make the purposes, technical solutions and beneficial technical effects of the present application clearer, the present application will be further described in detail below in combination with embodiments, and other advantages and effects of the present application can be easily understood by those skilled in the art from the contents disclosed in the present specification.

[0022] The present inventors have found a Bifidobacterium longum proliferation agent and further prepared a Bifidobacterium longum fermented milk by the Bifidobacterium longum proliferation agent through a large amount of practice research. The Bifidobacterium longum fermented milk prepared by the above-mentioned Bifidobacterium longum proliferation agent has the advantages of being naturally edible, having a good taste, having a low cost, being pure-strain fermented, being free of contamination by miscellaneous bacteria, and having a long survival time during storage, thereby greatly improving the product quality of the Bifidobacterium longum fermented milk. On this basis, the present application is completed.

[0023] The application provides a preparation method of Bifidobacterium longum fermented milk, which comprises the following steps: 1) providing a Bifidobacterium longum proliferant, wherein the Bifidobacterium longum proliferant comprises a slurry of cooked red beans and pineapple flesh; 2) mixing the Bifidobacterium longum proliferant provided in step 1) with milk to provide a fermentation system; and 3) inoculating the fermentation system provided in step 2) with Bifidobacterium longum and performing fermentation treatment. In the preparation method, the Bifidobacterium longum proliferant used can comprise a slurry of cooked red beans and pineapple flesh, and the growth of Bifidobacterium longum in the fermentation system can be effectively promoted in the fermentation process by introducing the Bifidobacterium longum proliferant into the fermentation system comprising milk and inoculating Bifidobacterium longum, and the contamination of miscellaneous bacteria (for example, aerobic contaminant bacteria, and more specifically, Bacillus subtilis, Escherichia coli and Bacillus licheniformis) in the prepared Bifidobacterium longum fermented milk can be effectively avoided.

[0024] In the preparation method of Bifidobacterium longum fermented milk, the Bifidobacterium longum proliferant comprising a slurry of cooked red beans and pineapple flesh can be provided. Generally, the Bifidobacterium longum proliferant needs to be prepared completely and separately first, and then the prepared Bifidobacterium longum proliferant is mixed with milk to construct a fermentation system, so that the growth of Bifidobacterium longum in the fermentation system can be effectively promoted in the fermentation process.

[0025] In the preparation method, the red beans generally refer to mature seeds of Vigna angularis, an annual semi-twining herbaceous plant of Leguminosae, which is usually mixed with an appropriate amount of water and cooked to provide cooked red beans, and then mixed with other raw materials to provide a homogenate. The pineapple flesh generally refers to the flesh of mature fruits of Ananas comosus (Linn.) Merr., a monocotyledonous plant of the genus Ananas of the family Bromeliaceae, which is usually fresh. In the Bifidobacterium longum proliferant, the total weight of 100 parts by weight can comprise 2-20 parts, 2-4 parts, 4-6 parts, 6-8 parts, 8-10 parts, 10-12 parts, 12-14 parts, 14-16 parts, 16-18 parts, 18-20 parts of red beans (calculated by dry weight, i.e., the weight of raw red beans before cooking). In the Bifidobacterium longum proliferant, the total weight of 100 parts by weight can comprise 5-30 parts, 5-10 parts, 10-15 parts, 15-20 parts, 20-25 parts, or 25-30 parts of pineapple flesh (calculated by wet weight).

[0026] In the above preparation method, the B. longum proliferation agent can comprise a slurry of cooked red beans and pineapple flesh. In the preparation of the B. longum proliferation agent, the cooked red beans and pineapple flesh can be homogenized and mixed to provide the B. longum proliferation agent. The B. longum proliferation agent can further comprise water, which can be present in an appropriate amount. Generally, an appropriate amount of water can be added during the cooking of the red beans and during the homogenization and mixing of the cooked red beans and pineapple flesh to facilitate the preparation of the B. longum proliferation agent. For example, the red beans can be cooked with an appropriate amount of water to provide the cooked red beans. For another example, an appropriate amount of water can be used to form the slurry of the cooked red beans and pineapple flesh. For yet another example, the homogenized mixture can be subjected to solid-liquid separation and / or sterilization to remove the solid materials from the homogenized mixture to provide a uniform slurry suitable for pure culture fermentation.

[0027] In the above preparation method of the fermented milk of B. longum, the B. longum proliferation agent provided in step 1) can be mixed with milk to provide a fermentation system. The B. longum proliferation agent obtained can be mixed with an appropriate amount of milk and other ingredients to form a suitable fermentation system for subsequent fermentation.

[0028] In the above preparation method, an appropriate amount of the B. longum proliferation agent is generally added to the fermentation system. Generally, a higher amount of the B. longum proliferation agent can effectively increase the number of viable B. longum, but when the amount is too high, it can affect the taste and flavor of the fermented milk. For example, the B. longum proliferation agent can be present in the fermentation system in an amount of 3-30 wt%, 3-4 wt%, 4-5 wt%, 5-6 wt%, 6-8 wt%, 8-10 wt%, 10-12 wt%, 12-15 wt%, 15-20 wt%, 20-25 wt%, or 25-30 wt%. The B. longum proliferation agent can be uniformly mixed in the fermentation system.

[0029] In the above preparation method, the fermentation system generally contains an appropriate amount of milk. The milk contained in the fermentation system can be raw milk or various dairy products prepared from raw milk and suitable for fermentation of B. longum dairy products. For example, the milk that can be used can be raw milk, liquid milk, reconstituted milk, etc. The amount of milk in the fermentation system can be appropriately adjusted by those skilled in the art. For example, the amount of milk in the fermentation system can be ≥5 wt%, 5-10 wt%, 10-20 wt%, 20-30 wt%, 30-40 wt%, 40-50 wt%, 50-60 wt%, 60-70 wt%, 70-80 wt%, 80-90 wt%, or higher.

[0030] In the above preparation method, the fermentation system can further comprise an additive. The type and amount of suitable additive for preparing the fermented milk should be adjustable by those skilled in the art. For example, the additive can be selected from the group consisting of one or more of a flavoring agent (e.g., sucrose, etc.), an acid-base stabilizer (e.g., sodium citrate, etc.), a thickening agent (e.g., pectin, starch, etc.), and the like. For another example, the amount of the flavoring agent added to the fermentation system can be 2.5-7.5 wt%, 2.5-3.5 wt%, 3.5-4.5 wt%, 4.5-5.5 wt%, 5.5-6.5 wt%, or 6.5-7.5 wt%. For yet another example, the amount of the acid-base stabilizer added to the fermentation system can be 0.1-1 wt%, 0.1-0.2 wt%, 0.2-0.4 wt%, 0.4-0.6 wt%, 0.6-0.8 wt%, or 0.8-1 wt%. For yet another example, the amount of the thickening agent added to the fermentation system can be 0.1-1 wt%, 0.1-0.2 wt%, 0.2-0.4 wt%, 0.4-0.6 wt%, 0.6-0.8 wt%, or 0.8-1 wt%.

[0031] In the above preparation method of the Bifidobacterium longum fermented milk, the fermentation system provided in step 2) can be inoculated with Bifidobacterium longum for fermentation treatment. After the Bifidobacterium longum proliferator is mixed with the appropriate proportion of milk and other ingredients to form a suitable fermentation system, the fermentation system can be subjected to fermentation treatment to provide the above-mentioned Bifidobacterium longum fermented milk.

[0032] In the above preparation method, Bifidobacterium longum is a kind of anaerobic gram-positive bacillus, belonging to the genus Bifidobacterium. In a specific embodiment of the present application, Bifidobacterium longum can be Bifidobacterium longum BL-05 or the like.

[0033] In the above preparation method, the fermentation system usually needs to be inoculated with an appropriate amount of Bifidobacterium longum. Before inoculating Bifidobacterium longum, the fermentation system or each component thereof (e.g., milk, water, etc.) can usually be subjected to sterilization treatment to ensure the pure strain fermentation effect in the fermentation treatment. The appropriate inoculation amount should be adjustable by those skilled in the art, for example, the inoculation concentration of Bifidobacterium longum in the fermentation system (calculated as the final concentration in the fermentation broth to be fermented) can be 0.1-200×10 6 CFU / g, 0.1-0.5×10 6 CFU / g, 0.5-1×10 6 CFU / g, 1-5×10 6 CFU / g, 5-10×10 6 CFU / g, 10-20×106 CFU / g, 20-40 x 10 6 CFU / g, 20-40 x 10 6 CFU / g, 40-60 x 10 6 CFU / g, 60-80 x 10 6 CFU / g, 80-100 x 10 6 CFU / g, 100-120 x 10 6 CFU / g, 120-140 x 10 6 CFU / g, 140-160 x 10 6 CFU / g, 160-180 x 10 6 CFU / g, or 180-200 x 10 6 CFU / g.

[0034] In the above preparation method, the fermentation treatment is usually a static fermentation treatment. A person skilled in the art can select appropriate fermentation treatment conditions according to the type of the bacterial strain. For example, the fermentation temperature of the fermentation treatment can be 36-38℃, 36-36.5℃, 36.5-37℃, 37-37.5℃, or 37.5-38℃. For another example, the fermentation time of the fermentation treatment can be 10-20h, 10-12h, 12-14h, 14-16h, 16-18h, or 18-20h.

[0035] The second aspect of the present application provides a B. longum fermented milk, which is prepared by the preparation method of the B. longum fermented milk provided by the first aspect of the present application. The B. longum fermented milk prepared by the above preparation method of the B. longum fermented milk has little contamination of miscellaneous bacteria (for example, aerobic contaminant bacteria, and more specifically, B. subtilis, E. coli, B. licheniformis, etc.) and has a good bacteria increasing effect. For example, in the aerobic contaminant bacteria counting experiment in the culture medium (for example, LB culture medium), the total number of aerobic bacterial colonies of the fermented milk can be <1 x 10 1 CFU / g. For another example, in the B. longum counting experiment in the culture medium (for example, TPY culture medium), the total number of B. longum colonies of the fermented milk can be ≥4 x 10 8 CFU / g, ≥6 x 10 8 CFU / g, ≥8 x 10 8 CFU / g, ≥1 x 10 9 CFU / g, ≥1.5 x 10 9 CFU / g, or ≥2 x 10 9CFU / g. In addition, the long bifidobacterium fermented milk prepared by the preparation method of long bifidobacterium fermented milk has a longer storage period. After one month of cold storage (under the condition of 10℃), the proportion of viable bacteria count can still be ≥10%, ≥15%, or ≥20%. In the experiment of counting long bifidobacterium in the fermentation medium (for example, TPY medium), the total number of long bifidobacterium colonies can still be ≥1.0×10 8 CFU / g, ≥1.5×10 8 CFU / g, or ≥2×10 8 CFU / g.

[0036] The preparation method of long bifidobacterium fermented milk and the long bifidobacterium fermented milk prepared by the preparation method have the advantages of natural edible, good taste, low cost, and the like, and belong to pure breed fermentation and have no contamination of miscellaneous bacteria. The prepared fermented milk has a long shelf life, thereby effectively solving the problems of other similar products in the prior art and having a good industrialization prospect.

[0037] The application will be further described below by examples, but the scope of the application is not limited by the examples.

[0038] Example 1

[0039] Preparation of long bifidobacterium proliferation agent:

[0040] Long bifidobacterium proliferation agent 1: 1 part by weight of red beans is soaked in water for 6 hours, and water is supplemented to 9 parts by weight. After being boiled (100℃ for 1-2 hours) and cooled, 2 parts by weight of fresh pineapple and 8 parts by weight of water are added and uniformly mixed. After being incubated at 55℃ for 4 hours, the residue is removed by filtration and sterilized, serving as a long bifidobacterium proliferation agent.

[0041] Long bifidobacterium proliferation agent 2: 1 part by weight of red beans is soaked in water for 10 hours, and water is supplemented to 9 parts by weight. After being boiled and cooled, 4 parts by weight of fresh pineapple and 6 parts by weight of water are added and uniformly mixed. After being incubated at 55℃ for 4 hours, the residue is removed by filtration and sterilized, serving as a long bifidobacterium proliferation agent.

[0042] Long bifidobacterium proliferation agent 3: 2 parts by weight of red beans are soaked in water for 16 hours, and water is supplemented to 8 parts by weight. After being boiled and cooled, 5 parts by weight of fresh pineapple and 5 parts by weight of water are added and uniformly mixed. After being incubated at 55℃ for 4 hours, the residue is removed by filtration and sterilized, serving as a long bifidobacterium proliferation agent.

[0043] Blank control: 1 part by weight of red beans is soaked in water for 16 hours, and water is supplemented to 9 parts by weight. After being boiled and cooled, 10 parts by weight of water is added and uniformly mixed. After being incubated at 55℃ for 4 hours, the residue is removed by filtration and sterilized, serving as a blank control of long bifidobacterium proliferation agent.

[0044] To determine the proliferation effect of Bifidobacterium longum, each of the above-prepared Bifidobacterium longum proliferation agents was added to milk (fresh milk, produced by Guangming Dairy Co., Ltd.) at a mass ratio of 10%, sterilized at 105°C for 10 min, and inoculated to obtain a final concentration of about 1.0 x 10 6 CFU / g (Bifidobacterium longum BL-05, DuPont Nutrition & Health). After 12 h of fermentation, samples were gradient-diluted, aerobic contaminant bacteria were counted using LB medium (counted after aerobic culture at 37°C for 48 h using LB agar medium), and Bifidobacterium was counted using TPY medium (counted after anaerobic culture at 37°C for 72 h using TPY agar medium), and the experimental results are shown in Table 1. As can be seen from the viable Bifidobacterium count results in Table 1, the prepared proliferation agents can all promote the growth of Bifidobacterium longum in milk, and the proliferation agent added with pineapple has a better bacteria-promoting effect, and the bacteria-promoting effect is further improved as the amount of added pineapple increases, while the bacteria-promoting effect of the proliferation agent without added pineapple is relatively poor. As can be seen from the total aerobic bacterial colony count results in Table 1, during the fermentation of pure Bifidobacterium, there is basically no contamination of miscellaneous bacteria, and the bacteria-promoting effect is reliable.

[0045] Table 1

[0046] Total aerobic plate count (CFU / g) TPY viable count (CFU / g) Method of manufacture 1 <1 x 10 1 ]]> 4.0 x 10 8 ]]> Method of manufacture 2 <1 x 10 1 ]]> 9.2 x 10 8 ]]> Method of manufacture 3 <1 x 10 1 ]]> 1.3 x 10 9 ]]> Blank control <1 x 10 1 ]]> 1.5 x 10 6 ]]>

[0047] Example 2

[0048] Preparation of Bifidobacterium longum fermented milk with added sodium citrate:

[0049] Bifidobacterium longum fermented milk formula: 50 parts by weight of raw milk, 10 parts by weight of sucrose, 1 part by weight of sodium citrate, and 0.2 parts of thickening agent (pectin (Zhengzhou Tianshun, food grade), same below). The proliferation agent was prepared according to the method in Example 1, Bifidobacterium longum proliferation agent 2, and the added amount of Bifidobacterium longum proliferation agent was 5 parts by weight, 10 parts by weight, 15 parts by weight, and 20 parts by weight, respectively, and the rest was adjusted to 100 parts by weight with water.

[0050] Preparation method: The above mixture was preheated and warmed, homogenized at 65°C and 20 MPa, sterilized at 105°C for 10 min, and cooled to 37°C. Bifidobacterium longum (same as in Example 1, final concentration about 1.0 x 10 6Fermentation was carried out for 8 hours (CFU / g). Samples were serially diluted, and aerobic contaminants were counted on LB medium, while Bifidobacteria were counted on TPY medium. The results are shown in Table 2. For sensory evaluation, five professionals tasted the fermented product and provided their evaluations. If the evaluations were inconsistent, the majority opinion prevailed. The evaluation results included acidity and taste. Acidity was categorized into four levels: sweet and sour, slightly sour, quite sour, and sour. Taste was categorized into three levels: palatable, bitter, and bitter. Table 2 shows that the number of viable Bifidobacteria increased with the addition of the growth promoter. When the addition was below 10%, the fermented milk was sweet and palatable, but when the addition was above 15%, the sensory characteristics leaned towards sourness and bitterness, resulting in a poor flavor. Table 2 shows that the total aerobic colony count indicated that there was virtually no contamination during the pure Bifidobacteria fermentation process, indicating pure culture fermentation.

[0051] Table 2

[0052]

[0053]

[0054] Example 3

[0055] Bifidobacterium longum survival rate in fermented milk during storage:

[0056] Fermented milk containing *Bifidobacterium longum* was prepared using the formula in Example 2 (with a 10% growth promoter). After packaging, it was stored at 10°C for 30 days, serially diluted, and aerobic contaminants were counted using LB medium, while *Bifidobacterium* was counted using TPY medium. The experimental results are shown in Table 3. As can be seen from the TPY viable count results in Table 3, the viable count in the sample did not decrease significantly within the 30-day shelf life, still reaching 2.2 × 10⁻⁶. 8 The CFU / g level is far higher than the minimum limit for live lactic acid bacteria count specified in the Hygienic Standard for Lactic Acid Bacteria Beverages (GB 16321-2003): 1.0 × 10⁻⁶. 6 According to the relevant regulations regarding "CFU / g", the *Bifidobacterium longum* in the sample had a high survival rate. As shown in Table 3, the total aerobic colony count results indicate that the sample remained essentially free of contamination during storage. Furthermore, the sample remained sweet and sour and remained stable after storage.

[0057] Table 3

[0058]

[0059] Example 4

[0060] Add a control experiment directly:

[0061] Method 1:

[0062] Soak 1 part red beans in water for 6 hours, then add water to bring the total weight to 9 parts. Cook until done and cool. Add 2 parts fresh pineapple and 8 parts water, and mix well. Keep warm at 50℃ for 3 hours, filter to remove residue, and sterilize. Use as a growth promoter for Bifidobacterium longum.

[0063] Ingredients: 50 parts by weight of raw milk, 10 parts by weight of sucrose, 1 part by weight of sodium citrate, 0.1 parts by weight of thickener, 10 parts by weight of Bifidobacterium longum growth promoter, and the remainder adjusted to 100 parts by weight with water. The mixture was preheated, homogenized at 65°C and 20 MPa, sterilized at 105°C for 10 minutes, and then cooled to 37°C. Bifidobacterium longum was inoculated (strain same as in Example 1, final concentration approximately 3.0 × 10⁻⁶). 6 Fermentation was carried out for 12 hours (CFU / g). Samples were serially diluted, and aerobic contaminants were counted on LB medium, while Bifidobacteria were counted on TPY medium.

[0064] Method 2:

[0065] Soak 1 part by weight of red beans in water for 6 hours, then add water to make 9 parts by weight. Cook until done, then cool to make red bean milk. Ingredients: 50 parts by weight of raw milk, 10 parts by weight of sucrose, 1 part by weight of sodium citrate, 0.1 part by weight of thickener, 5 parts by weight of red bean milk, 1 part by weight of fresh pineapple, and adjust the weight with water to make 100 parts by weight. Other operations are the same as in Example 1 of this embodiment.

[0066] The experimental results are shown in Table 4. Method 1 first prepared the Bifidobacterium longum growth agent separately and completely, and then mixed the prepared Bifidobacterium longum growth agent with milk to construct the fermentation system, which had a better growth effect. Method 2 had the same content of each substance in the formula as Method 1, but in Method 2, red beans and pineapple were directly mixed with other components of the fermentation system, so the growth effect was not good.

[0067] Table 4

[0068]

[0069] In summary, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0070] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for preparing a fermented milk containing Bifidobacterium longum, comprising: 1) Provide a Bifidobacterium longum growth agent, wherein the Bifidobacterium longum growth agent comprises a slurry of cooked red beans and pineapple pulp, and the preparation method of the Bifidobacterium longum growth agent comprises: homogenizing and mixing cooked red beans and pineapple pulp, and incubating at 55°C for 4 hours or at 50°C for 3 hours, wherein the total weight of the Bifidobacterium longum growth agent, based on 100 parts by weight, comprises: 4-12 servings of red beans; 10-30 servings of pineapple pulp; 2) Mix the Bifidobacterium longum growth promoter provided in step 1) with milk to provide a fermentation system, wherein the content of the Bifidobacterium longum growth promoter in the fermentation system is 5-10 wt%; 3) Inoculate the fermentation system provided in step 2) with Bifidobacterium longum and ferment it.

2. The method for preparing Bifidobacterium longum fermented milk as described in claim 1, characterized in that, Step 1) further includes: solid-liquid separation and / or sterilization.

3. The method for preparing Bifidobacterium longum fermented milk as described in claim 1, characterized in that, In step 2), the milk is selected from one or more combinations of raw milk, liquid milk, and reconstituted milk.

4. The method for preparing Bifidobacterium longum fermented milk as described in claim 1, characterized in that, In step 2), the fermentation system further includes additives, which are selected from one or more combinations of flavoring agents, acid-base stabilizers, and thickeners.

5. The method for preparing Bifidobacterium longum fermented milk as described in claim 1, characterized in that, In step 3), the Bifidobacterium longum is Bifidobacterium longum BL-05.

6. The method for preparing Bifidobacterium longum fermented milk as described in claim 1, characterized in that, In step 3), the inoculation concentration of Bifidobacterium longum in the fermentation system is 0.1~200×10⁻⁶. 6 CFU / g.

7. The method for preparing Bifidobacterium longum fermented milk as described in claim 1, characterized in that, In step 3), the fermentation temperature of the fermentation treatment is 36~38℃; And / or, the fermentation time of the fermentation treatment is 10~20h; And / or, the fermentation treatment is a static fermentation treatment.

8. A Bifidobacterium longum fermented milk, prepared by the method for preparing Bifidobacterium longum fermented milk according to any one of claims 1 to 7.

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