阅读说明：本技术 一种植物乳杆菌发酵乳粉及其制备方法 (Lactobacillus plantarum fermented milk powder and preparation method thereof ) 是由 韩瑨 吴正钧 张欢畅 刘景玉 王晓花 于 2020-12-25 设计创作，主要内容包括：本发明公开了一种植物乳杆菌发酵乳粉及其制备方法,包括以下步骤：将植物乳杆菌(Lactobacillus plantarum)CGMCC NO.0847接种于含高粱秸秆成分的脱脂乳中进行发酵得发酵乳,再经冻干后得发酵乳粉。首次将含高粱秸秆成分的脱脂乳作为培养基接种植物乳杆菌CGMCC NO.0847进行发酵并冻干,制备得到植物乳杆菌发酵乳粉,披露了高粱秸秆汁具有促进植物乳杆菌在脱脂乳中增殖的功能。与其他同样以单一发酵剂制备的植物乳杆菌发酵乳粉相比,本发明制备的植物乳杆菌发酵乳粉活菌数更高,并且,口味更易于被消费者接受。与其他以后添加方式制备的植物乳杆菌发酵乳粉相比,安全性更高、操作更简易。(The invention discloses lactobacillus plantarum fermented milk powder and a preparation method thereof, wherein the lactobacillus plantarum fermented milk powder comprises the following steps: lactobacillus plantarum (Lactobacillus plantarum) CGMCC NO.0847 is inoculated into skim milk containing sorghum straw for fermentation to obtain fermented milk, and then the fermented milk powder is obtained after freeze-drying. The skim milk containing sorghum straw is used as a culture medium to be inoculated with lactobacillus plantarum CGMCC NO.0847 for the first time for fermentation and freeze-drying to prepare lactobacillus plantarum fermented milk powder, and the sorghum straw juice has the function of promoting the proliferation of lactobacillus plantarum in the skim milk. Compared with other lactobacillus plantarum fermented milk powder prepared by a single leaven, the lactobacillus plantarum fermented milk powder prepared by the invention has higher viable count and more easily accepted taste by consumers. Compared with lactobacillus plantarum fermented milk powder prepared in other later adding modes, the lactobacillus plantarum fermented milk powder is higher in safety and simpler to operate.)

1. A preparation method of lactobacillus plantarum fermented milk powder is characterized by comprising the following steps: lactobacillus plantarum (Lactobacillus plantarum) CGMCC NO.0847 is inoculated into skim milk containing sorghum straw for fermentation to obtain fermented milk, and then the fermented milk powder is obtained after freeze-drying.

2. The method for preparing lactobacillus plantarum fermented milk powder according to claim 1, wherein the lactobacillus plantarum CGMCC No.0847 is inoculated in an amount of 1x10⁷～5x10⁷ cfu/mL。

3. The preparation method of lactobacillus plantarum fermented milk powder according to claim 1, wherein the skim milk containing sorghum straw components comprises 3-12% of sorghum straw juice freeze-dried powder, 1-8% of skim milk powder and the balance of water to 100%, wherein the percentages are mass percentages of the components in the total mass of the raw materials.

4. The preparation method of the lactobacillus plantarum fermented milk powder according to claim 1, wherein the skim milk contains sucrose in a proportion of 1-7% by mass of each component in the total mass of the raw materials.

5. The method for preparing lactobacillus plantarum fermented milk powder according to claim 1, wherein the fermentation temperature is 26 ℃ to 42 ℃.

6. The method for preparing lactobacillus plantarum fermented milk powder according to claim 1, wherein the fermentation mode is anaerobic culture.

7. The method for preparing lactobacillus plantarum fermented milk powder according to claim 1, wherein the fermentation time is 6-18 hours.

8. A lactobacillus plantarum fermented milk powder characterized by being prepared by the preparation method of any one of claims 1 to 7.

9. The lactobacillus plantarum fermented milk powder according to claim 8, wherein the viable count of lactobacillus plantarum CGMCC NO.0847 in the lactobacillus plantarum fermented milk powder is more than 5x10⁹ cfu/g。

Technical Field

The invention belongs to the field of fermented milk powder, and particularly relates to a preparation method of lactobacillus plantarum fermented milk powder. In addition, the invention also relates to lactobacillus plantarum fermented milk powder.

Background

The species and quantity of probiotics are important factors influencing the probiotic function and health care function of the product, however, most of the traditional lactobacillus for fermentation, such as lactobacillus bulgaricus, streptococcus thermophilus and the like, cannot tolerate high-acidity and high-osmotic-pressure gastrointestinal fluid, and as a result, most of the lactobacillus for fermentation pass through the human digestive tract to be killed, and only a small amount of strains enter the intestinal tract, so that great obstacles are formed to the probiotic function, such as the exertion of the lactobacillus bulgaricus and the like.

Compared with the traditional lactobacillus fermentation strain, the lactobacillus plantarum has more excellent digestive juice tolerance, and researches show that the lactobacillus plantarum can effectively survive in bile of various digestive enzymes, low-pH gastric juice and high osmotic pressure, and in addition, the lactobacillus plantarum has quite excellent colonization capacity in intestinal tracts. More importantly, the lactobacillus plantarum has multiple beneficial human body functions of reducing cholesterol, regulating blood fat, regulating intestinal flora balance, promoting digestion and absorption and the like.

The fermented milk powder is a novel probiotic microbial inoculum obtained by multiplying probiotics in milk and then freeze-drying the probiotics, and can provide sufficient probiotics and nutrient substances for eaters. However, lactobacillus plantarum hardly grows and proliferates in cow's milk, and even in foreign countries where fermented milk products are more highly promoted, there are few reports on the production of fermented milk using lactobacillus plantarum. In addition, it has been reported that the growth of lactobacillus plantarum in skim milk is promoted by adding various proliferation factors (such as soybean peptide, amino acid, etc.) to skim milk, but the flavor of these fermented milk products is generally not acceptable to consumers. Therefore, the current probiotic fermented milk powder containing non-proliferation probiotics in milk such as lactobacillus plantarum can only be prepared by adding bacteria powder after, but the complexity of the process and the potential food safety are increased. Therefore, the preparation of fermented milk powder which is fermented by using lactobacillus plantarum as a single leavening agent, has a taste accepted by consumers, and is simple and safe in process is a problem to be solved by those skilled in the art.

Lactobacillus plantarum ST-III CGMCC NO.0847 reported in Chinese invention patents ZL03116377.7 and ZL200410066891.7 has the functions of resisting hyperglycemia, reducing blood fat, reducing cholesterol, adhering epithelial cells of intestinal tracts and the like, and has obvious probiotic effect. Meanwhile, the lactobacillus plantarum ST-III is also the first strain which is publicly reported and industrialized in China, the application value of the lactobacillus plantarum ST-III is expanded, and the lactobacillus plantarum ST-III has important significance for the development of the dairy industry in China.

Disclosure of Invention

Based on the technical problems, the invention provides lactobacillus plantarum fermented milk powder and a preparation method thereof, and the method can be used for carrying out skim milk fermentation by using a single lactobacillus plantarum starter to prepare the lactobacillus plantarum fermented milk powder with the number of viable bacteria being more than 5x10⁹cfu/g, the taste is accepted by consumers, and the process is simple and safe.

Specifically, the invention provides a preparation method of lactobacillus plantarum fermented milk powder on one hand, which comprises the following steps: lactobacillus plantarum (Lactobacillus plantarum) CGMCC NO.0847 is inoculated into skim milk containing sorghum straw for fermentation to obtain fermented milk, and then the fermented milk powder is obtained after freeze-drying.

Further, the inoculation amount of the lactobacillus plantarum CGMCC NO.0847 is 1x10⁷～5x10⁷cfu/mL。

Further, the skim milk containing the sorghum straw comprises 3-12% of sorghum straw juice freeze-dried powder, 1-8% of sorghum straw juice freeze-dried powder and water, wherein the percentage is the mass percentage of each component in the total mass of the raw materials.

Further, the skim milk comprises sucrose, wherein the sucrose accounts for 1-7%, and the percentage is the mass percentage of each component in the total mass of the raw materials. The sucrose is well weighed together with the sorghum straw juice freeze-dried powder and the skim milk powder, and the mixture is mixed together and added with water to be dissolved, so that the skim milk containing the sorghum straw components is obtained.

Further, the temperature of the fermentation is 26 ℃ to 42 ℃.

Further, the above-mentioned fermentation method is anaerobic culture.

Further, the fermentation time is 6-18 h.

In a second aspect, the invention also provides lactobacillus plantarum fermented milk powder prepared by any one of the preparation methods.

Furthermore, the viable count of the lactobacillus plantarum CGMCC NO.0847 in the fermented milk powder is more than 5x10⁹ cfu/g。

Compared with the prior art, the preparation method in the technical scheme comprises the steps of inoculating the skim milk containing sorghum straw components as a culture medium to lactobacillus plantarum CGMCC NO.0847 for fermentation and freeze-drying for the first time to prepare lactobacillus plantarum fermented milk powder, and discloses that sorghum straw juice has the function of promoting lactobacillus plantarum to proliferate in the skim milk, and the viable count of the lactobacillus plantarum CGMCC NO.0847 in the finally obtained fermented milk powder is more than 5x10⁹cfu/g. Compared with other lactobacillus plantarum fermented milk powder prepared by a single leaven, the lactobacillus plantarum fermented milk powder prepared by the method has higher viable count and is more acceptable to consumers in taste. Compared with lactobacillus plantarum fermented milk powder prepared in other later adding modes, the lactobacillus plantarum fermented milk powder is higher in safety and simpler to operate.

Detailed Description

In order to more clearly illustrate the technical solution of the present invention, the technical solution of the present invention will be further illustrated with reference to the following specific embodiments:

in a specific embodiment, a method for preparing lactobacillus plantarum fermented milk powder is provided, which comprises the following steps: lactobacillus plantarum (Lactobacillus plantarum) CGMCC NO.0847 is inoculated into skim milk containing sorghum straw for fermentation to obtain fermented milk, and then the fermented milk powder is obtained after freeze-drying.

According to the preparation method in the technical scheme, skim milk containing sorghum straw is used as a culture medium to be inoculated with lactobacillus plantarum CGMCC NO.0847 for fermentation and freeze-drying for the first time, and lactobacillus plantarum fermented milk powder is prepared, so that sorghum straw juice has the function of promoting lactobacillus plantarum to proliferate in the skim milk. Compared with other lactobacillus plantarum fermented milk powder prepared by a single leaven, the lactobacillus plantarum fermented milk powder prepared by the invention has higher viable count and more easily accepted taste by consumers. Compared with lactobacillus plantarum fermented milk powder prepared in other later adding modes, the lactobacillus plantarum fermented milk powder is higher in safety and simpler to operate.

Further onThe inoculation amount of the lactobacillus plantarum CGMCC NO.0847 is 1x10⁷～5x10⁷cfu/mL; preferably 2x10⁷～4x10⁷cfu/mL, more preferably 3X10⁷cfu/mL。

The preferable skim milk containing the sorghum straw components is prepared manually, the prepared skim milk comprises 3-12% by mass of sorghum straw juice freeze-dried powder, 1-8% by mass of sorghum straw juice freeze-dried powder and the balance of water, and the mass of the skim milk accounts for the total mass of the raw materials. The preparation method can comprise the following steps: adding the defatted milk powder and the sorghum straw juice freeze-dried powder into distilled water, uniformly mixing and fully dissolving, sterilizing at 95-125 ℃ for 5-20 minutes, and cooling to obtain the sorghum straw juice freeze-dried powder.

The preferable skim milk comprises sucrose, and the mass percentage of the sucrose in the total mass of the raw materials is 1-7%; preferably 3 to 5%; more preferably 4%.

The preferable fermentation temperature is 26-42 ℃; preferably 30-40 ℃; more preferably 37 deg.c.

The preferable fermentation time is 6-18 h; preferably 9 to 15 hours; more preferably 12 h.

The preferred mode of fermentation is anaerobic culture.

It can also be seen from the combination of the example and the comparative example 2 that the proliferation effect of Lactobacillus plantarum CGMCC NO.0847 in skim milk is significantly reduced when the fermentation parameters are outside the range of the preferred fermentation parameters. In the preferred range, the inoculation amount, the skim milk concentration, the sorghum straw concentration, the fermentation temperature and the fermentation time are mutually influenced, so that the viable bacteria number in the lactobacillus plantarum CGMCC NO.0847 fermented milk powder is higher. For example, when the inoculation amount is too small, the propagation rate of the strain is slow, so that the number of viable bacteria in the finally obtained fermented milk powder is lower than the preferable inoculation amount range. For another example, when the concentration of sorghum stalks is lower than the preferred range, the amount of substances stimulating the proliferation of strains is less, and the number of viable bacteria in the fermented milk powder is also reduced.

In another embodiment, there is provided a lactobacillus plantarum fermented milk powder produced by any of the above-described methods for producing a fermented milk powder.

Furthermore, the viable count of the lactobacillus plantarum CGMCC NO.0847 in the fermented milk powder is more than 5x10⁹ cfu/g。

Furthermore, the fermented milk powder has good flavor and no peculiar smell. The fermented milk powder has better taste than other lactobacillus plantarum fermented milk powder prepared by a single leavening agent.

The following examples further illustrate the above embodiments, but do not therefore limit the invention within the scope of the examples described. The experimental methods without specifying specific conditions in the following examples were selected according to the conventional methods and conditions, or according to the commercial instructions.

In the examples below, all the starting materials are commercially available and meet the relevant national standards.

Example 1

1. Materials and methods

(a) Preparation of seeds (fermentation strain):

lactobacillus plantarum CGMCC NO. 0847: dissolving Lactobacillus plantarum CGMCC NO.0847 lyophilized powder with a small amount of sterile distilled water, taking a loop by using an inoculating loop, streaking the loop on an MRS solid culture medium (purchased from Merck Co., USA), carrying out anaerobic culture at 37 ℃ for 24h, taking out a single colony by using the inoculating loop, putting the single colony into a 10mL MRS liquid culture medium (purchased from Merck Co., USA), uniformly dispersing the colony in the liquid culture medium by using a vortex oscillator, carrying out anaerobic culture at 37 ℃ for 24h, taking out the single colony, inoculating the single colony on the MRS liquid culture medium (purchased from Merck Co., USA) in an inoculation amount of 2% (v/v), carrying out anaerobic culture at 37 ℃ for 24h, centrifuging the culture at 15000rpm for 10min, discarding the supernatant, washing thalli for 2 times by using sterile distilled water, suspending the thalli by using sterile distilled water with the original culture volume to obtain a seed solution for fermentation, wherein the bacterial concentration of the seed solution is 1x 35⁹cfu/mL。

(b) Preparing sorghum straw juice freeze-dried powder: peeling sorghum straws, juicing, centrifuging at 15000rpm for 10min, collecting supernatant, and freeze drying.

(c) Preparation of skim milk: uniformly mixing 8% of skimmed milk powder and 4% of sorghum straw juice freeze-dried powder with distilled water, fully dissolving, adding 4% of sucrose by mass, fully dissolving, sterilizing at 125 deg.C for 5min, and cooling to room temperature to obtain the desired skimmed milk.

2. Preparation of lactobacillus plantarum fermented milk powder

Inoculating Lactobacillus plantarum CGMCC NO.0847 seed liquid with the inoculation amount of 3% (v/v, the seed liquid accounts for the volume percent of skim milk, the same below) in sterile milk containing 4% (w/w, mass percent, the same below) of sucrose, 4% (w/w, mass percent, the same below) of sorghum straw components and 8% (w/w, mass percent, the same below) of skim milk powder, carrying out anaerobic culture at 37 ℃ for 12h to obtain fermented milk, and freeze-drying to obtain the fermented milk powder A.

Example 2

1. Materials and methods

(a) Preparation of seeds (fermentation strain): the same as in example 1.

(b) Preparing sorghum straw juice freeze-dried powder: the same as in example 1.

(c) Preparation of skim milk: uniformly mixing 12% of skimmed milk powder and 1% of sorghum straw juice freeze-dried powder with distilled water, fully dissolving, adding 7% of sucrose by mass, fully dissolving, sterilizing at 95 ℃ for 20min, and cooling to room temperature to obtain the skimmed milk.

2. Preparation of lactobacillus plantarum fermented milk powder

The lactobacillus plantarum CGMCC NO.0847 seeds are aseptically inoculated to 12% (w/w) skim milk containing 7% (w/w) of sucrose and 1% (w/w) of sorghum straw by the inoculation amount of 1% (v/v), and are anaerobically cultured for 18h at 42 ℃ to obtain fermented milk, and then the fermented milk powder B is obtained after freeze-drying.

Example 3

1. Materials and methods

(a) Preparation of seeds (fermentation strain): the same as in example 1.

(b) Preparing sorghum straw juice freeze-dried powder: the same as in example 1.

(c) Preparation of skim milk: uniformly mixing 3% of skimmed milk powder and 8% of sorghum straw juice freeze-dried powder with distilled water, fully dissolving, adding 1% of sucrose by mass, fully dissolving, sterilizing at 100 ℃ for 15min, and cooling to room temperature to obtain skimmed milk.

2. Preparation of lactobacillus plantarum fermented milk powder

The lactobacillus plantarum CGMCC NO.0847 seeds are aseptically inoculated to 3% (w/w) skim milk containing 1% (w/w) of sucrose and 8% (w/w) of sorghum straw by an inoculation amount of 5% (v/v), and are anaerobically cultured for 6h at 26 ℃ to obtain fermented milk, and then the fermented milk powder C is obtained after freeze-drying.

Example 4

1. Materials and methods

(a) Preparation of seeds (fermentation strain): the same as in example 1.

(b) Preparing sorghum straw juice freeze-dried powder: the same as in example 1.

(c) Preparation of skim milk: uniformly mixing 10% of skimmed milk powder and 6% of sorghum straw juice freeze-dried powder with distilled water, fully dissolving, adding 5% of sucrose by mass, fully dissolving, sterilizing at 120 ℃ for 10min, and cooling to room temperature to obtain the skimmed milk.

2. Preparation of lactobacillus plantarum fermented milk powder

Inoculating Lactobacillus plantarum CGMCC NO.0847 seed with an inoculation amount of 4% (v/v) aseptically into skim milk containing 5% (w/w) of sucrose, 6% (w/w) of sorghum straw and 10% (w/w) of skim milk powder, carrying out anaerobic culture at 40 ℃ for 15h to obtain fermented milk, and freeze-drying to obtain fermented milk powder D.

Example 5

1. Materials and methods

(a) Preparation of seeds (fermentation strain): the same as in example 1.

(b) Preparing sorghum straw juice freeze-dried powder: the same as in example 1.

(c) Preparation of skim milk: uniformly mixing 5% of skimmed milk powder and 2% of sorghum straw juice freeze-dried powder with distilled water, fully dissolving, adding 3% of sucrose by mass, fully dissolving, sterilizing at 115 ℃ for 12min, and cooling to room temperature to obtain skimmed milk.

2. Preparation of lactobacillus plantarum fermented milk powder

Inoculating Lactobacillus plantarum CGMCC NO.0847 seed with an inoculation amount of 2% (v/v) aseptically into skim milk containing 3% (w/w) of sucrose, 2% (w/w) of sorghum straw and 5% (w/w) of skim milk powder, anaerobically culturing at 30 ℃ for 9h to obtain fermented milk, and freeze-drying to obtain fermented milk powder E.

Effect example 1Detection of viable bacteria in fermented milk powder

Viable bacteria count was performed on the lactobacillus plantarum fermented milk powder products A, B, C, D and E prepared in the above examples 1-5, and the results are shown in table 1.

TABLE 1 viable count results of Lactobacillus plantarum fermented milk powder

As shown in Table 1, the viable count of the lactobacillus plantarum fermented milk powder prepared by the method in the technical scheme of the invention is stably maintained at 5x10⁹CFU/g is higher than the standard.

Comparative example 1

Comparing the fermentation conditions of the lactobacillus plantarum CGMCC NO.0847 in sorghum straw juice, skim milk and skim milk prepared from sorghum straws, the specific operation is as follows:

1. materials and methods

(a) Preparation of seeds (fermentation strain): the same as in example 1.

(b) Preparing sorghum straw juice freeze-dried powder: the same as in example 1.

(c) Preparation of culture medium:

(1) preparing sorghum straw juice: uniformly mixing 4% sorghum straw juice freeze-dried powder with distilled water, fully dissolving, then adding 4% sucrose by mass, fully dissolving, sterilizing at 125 ℃ for 5min, and cooling to room temperature to obtain the sorghum straw juice.

(2) Preparation of skim milk: uniformly mixing 8% of skimmed milk powder with distilled water, dissolving completely, adding 4% of sucrose, dissolving completely, sterilizing at 125 deg.C for 5min, and cooling to room temperature to obtain the desired skimmed milk.

(3) Preparing skim milk containing sorghum straw components: the same as in example 1.

2. Fermentation of Lactobacillus plantarum in different culture media.

The lactobacillus plantarum CGMCC NO.0847 seed is aseptically inoculated in the three culture media according to the inoculum size of 3% (v/v), anaerobically cultured for 12h at 37 ℃, taken out and counted by viable bacteria, and the results are shown in Table 2.

TABLE 2 fermentation of Lactobacillus plantarum in different culture media

As shown in Table 2, when Lactobacillus plantarum CGMCC NO.0847 seed was inoculated in 3% (v/v) of the inoculum size to the fermentation system, the number of initial fermentation broth was 3X10⁷CFU/mL, and the number of viable bacteria at the end of fermentation in skim milk is 3.12X 10⁷CFU/mL, the Lactobacillus plantarum CGMCC NO.0847 shows almost no growth and proliferation in skim milk. Secondly, when lactobacillus plantarum CGMCC NO.0847 is inoculated in sorghum straw juice for fermentation, lactobacillus plantarum CGMCC NO.0847 has a certain growth effect (the multiplication rate is 3.9 times), but the multiplication effect is most remarkable in skim milk containing sorghum straw components (the multiplication rate is 28.7 times), and the capability of promoting lactobacillus plantarum to multiply in skim milk of sorghum straw juice is unpredictable.

Comparative example 2

The inoculation amount, skim milk concentration, sorghum straw concentration, culture temperature and fermentation time in example 1 were adjusted one by one to obtain a set of lactobacillus plantarum fermented milk powders prepared by different methods, and the viable count of the fermented milk powders obtained from each set is shown in table 3.

TABLE 3 viable count of Lactobacillus plantarum fermented milk powder prepared by different methods

From the results shown in table 3, it can be seen that when the inoculation amount, skim milk concentration, sorghum straw concentration, culture temperature and fermentation time in the preparation method of the fermented milk powder are adjusted to be outside the preferred range, lactobacillus plantarum CGMCC No.0847 can still obtain partial proliferation growth in skim milk, but the proliferation effect is obviously reduced, so that the number of viable bacteria in the prepared fermented milk powder is far lower than that of the fermented milk powder prepared in the preferred range.

Comparative example 3

Soybean is the most reported natural culture medium capable of promoting proliferation of lactobacillus plantarum at present, and compounding soybean milk and milk is studied for proliferation and fermentation of lactobacillus plantarum, so in this comparative example, soybean milk is used as a comparative object, lactobacillus plantarum fermented milk powder is prepared by the method in example 1, and the proliferation effect, the product taste and the preference degree of the two are compared, and the specific operation is as follows:

1. materials and methods

(a) Preparation of seeds (fermentation strain): the same as in example 1.

(b) Preparing sorghum straw juice freeze-dried powder: the same as in example 1.

Preparing soybean milk freeze-dried powder: weighing 50g soybean, adding appropriate amount of water, soaking at 37 deg.C for 4h, adding appropriate amount of water, pulping with a homogenizer, filtering the obtained pulp with gauze to remove residue, centrifuging (15000rpm for 10 min) to remove precipitate, and freeze drying the supernatant to obtain soybean milk lyophilized powder.

(c) Preparation of skim milk: uniformly mixing 8% of skimmed milk powder and 4% of sorghum straw juice freeze-dried powder (or soybean milk freeze-dried powder) with distilled water, adding 4% of sucrose by mass, fully dissolving, sterilizing at 125 deg.C for 5min, and cooling to room temperature to obtain the desired skimmed milk.

2. Preparation of lactobacillus plantarum fermented milk powder

Inoculating Lactobacillus plantarum CGMCC NO.0847 seeds with 3% (v/v) of inoculation amount to 8% (w/w) skim milk containing 4% (w/w) of sucrose and 4% (w/w) of sorghum straw (or soybean milk), carrying out anaerobic culture at 37 ℃ for 12h to obtain fermented milk, and freeze-drying to obtain the corresponding Lactobacillus plantarum fermented milk powder.

3. Viable count comparison

The lactobacillus plantarum fermented milk powder prepared by the above method was counted, and the results are shown in table 4.

TABLE 4 viable count results of Lactobacillus plantarum fermented milk powder

As can be seen from table 4, the number of viable bacteria in the fermented milk powder containing the sorghum straw component is higher than that of the fermented milk powder containing the soybean milk component under the condition of the same addition amount (4%), which indicates that the sorghum straw juice has better capability of promoting the proliferation of lactobacillus plantarum in skim milk than the soybean milk.

4. Comparison of product taste with preference

Taking the lactobacillus plantarum fermented milk powder prepared by the method as an experimental object, and carrying out taste test on the product. The number of test persons was 50. Tasting mode: tasting in a mode of unmarked scoring; the color, flavor, taste and nutrition of the fermented milk powder product are respectively and independently scored, each full score is 25, the average score and the total score thereof are calculated, and the statistical results are recorded in table 5. Meanwhile, the number of people who like each individual product is counted according to the opinion given to the overall like degree of the product, and the counting result is recorded in table 6.

TABLE 5 statistical table of taste test result data of products

Table 6 product preference test result data statistical table

In terms of product taste, the fermented milk powder containing sorghum straw is much higher in score than the fermented milk powder containing soybean milk because the fermented milk powder is good in flavor and free from peculiar smell, and the soybean milk component of the soybean milk has obvious fishy smell after being fermented by microorganisms, so that the fermented milk powder is more favored. The above-mentioned difference in flavor of the product directly causes a great difference in the degree of preference of the product, as most of the testers (37 persons) showed that the fermented milk powder containing the sorghum stalk ingredient was preferred, while none of them preferred the fermented milk powder containing the soymilk ingredient, and on the contrary, more persons (41 persons) did not prefer the fermented milk powder containing the soymilk ingredient.

According to the taste and the preference degree of the product, the lactobacillus plantarum fermented milk powder prepared by the method in the technical scheme of the invention is superior to the lactobacillus plantarum fermented milk powder containing soybean milk in aspects of product flavor, taste, nutrition and the like, and the lactobacillus plantarum fermented milk powder can be accepted by most consumers.

The lactobacillus plantarum fermented milk powder and the preparation method thereof provided by the invention are described in detail above. The principles and embodiments of the present invention are explained herein using specific examples, which are presented only to assist in understanding the method and its core concepts. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.