阅读说明：本技术 一种植物乳杆菌发酵乳及其制备方法 (Lactobacillus plantarum fermented milk and preparation method thereof ) 是由 韩瑨 吴正钧 王超越 王晓花 张欢畅 刘景玉 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,得到发酵乳。上述技术方案中的制备方法,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,制备得到植物乳杆菌发酵乳,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相比,本发明制备的植物乳杆菌发酵乳活菌数更高,并且口味更易于被消费者接受。(The invention discloses lactobacillus plantarum fermented milk and a preparation method thereof, wherein the lactobacillus plantarum fermented milk comprises the following steps: lactobacillus plantarum (Lactobacillus plantarum) CGMCC NO.0847 is inoculated into skim milk containing sorghum straw for fermentation to obtain the fermented milk. 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 for the first time, and lactobacillus plantarum fermented milk 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 milks which are also prepared by a single leavening agent, the lactobacillus plantarum fermented milks prepared by the method have higher viable count and are more acceptable to consumers in taste.)

1. The preparation method of the lactobacillus plantarum fermented milk is characterized by comprising the following steps of: lactobacillus plantarum (Lactobacillus plantarum) CGMCC NO.0847 is inoculated into skim milk containing sorghum straw for fermentation to obtain the fermented milk.

2. The method for preparing lactobacillus plantarum fermented milk 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 according to claim 1, wherein the sorghum straw component-containing skim milk comprises 3-12% of sorghum straw juice lyophilized powder, 1-8% of sorghum straw juice lyophilized 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 method for preparing lactobacillus plantarum fermented milk according to claim 1, wherein the skim milk comprises sucrose in a proportion of 1-7% by mass of each component in the total mass of the raw materials.

5. The method for producing fermented milk with lactobacillus plantarum according to claim 1, wherein the temperature of fermentation is 26 ℃ -42 ℃.

6. The method for producing fermented milk with lactobacillus plantarum according to claim 1, wherein the fermentation means is anaerobic culture.

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

8. A lactobacillus plantarum fermented milk produced by the method for producing a lactobacillus plantarum fermented milk according to any one of claims 1 to 7.

9. The lactobacillus plantarum fermented milk according to claim 8, wherein the viable count of lactobacillus plantarum CGMCC No.0847 in the lactobacillus plantarum fermented milk is > 5x10⁸ cfu/mL。

Technical Field

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

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.

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 taste of these fermented milk products is generally not acceptable to consumers. Therefore, the preparation of fermented milk which is fermented by lactobacillus plantarum as a single starter and has a taste acceptable to consumers 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 a preparation method of lactobacillus plantarum fermented milk, and a single lactobacillus plantarum fermented milk can be used by adopting the methodFermenting skim milk with Lactobacillus plantarum starter to obtain a fermented product with viable bacteria number greater than 5x10⁸cfu/mL, and a taste accepted by consumers.

Specifically, on one hand, the preparation method of the lactobacillus plantarum fermented milk is provided, and comprises the following steps: lactobacillus plantarum (Lactobacillus plantarum) CGMCC NO.0847 is inoculated into skim milk containing sorghum straw for fermentation to obtain the fermented milk.

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 skim milk powder, 1-8% of sorghum straw juice freeze-dried powder and the balance of water to 100%, 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.

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

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

Further, the fermentation time is 6-18 h.

In a second aspect, the lactobacillus plantarum fermented milk is provided, and is prepared by any one of the preparation methods.

Furthermore, the viable count of the lactobacillus plantarum CGMCC NO.0847 in the fermented milk is more than 5x10⁸cfu/mL。

Compared with the prior art, the preparation method in the technical scheme has the advantages that skim milk containing sorghum straw components is used as a culture medium to be inoculated with lactobacillus plantarum CGMCC NO.0847 for fermentation for the first time, and lactobacillus plantarum fermented milk 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 milks prepared by using a single leavening agent, the lactobacillus plantarum fermented milks prepared by the method have higher viable count, are good in flavor, have no peculiar smell, and are more acceptable to consumers.

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 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 the fermented milk.

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 for the first time, and lactobacillus plantarum fermented milk 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 milks which are also prepared by a single leavening agent, the lactobacillus plantarum fermented milks prepared by the method have higher viable count and are more acceptable to consumers in taste.

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

The optimized skim milk containing the sorghum straw 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 water. The preparation method can comprise the following steps: adding skimmed milk powder and jowar straw juice lyophilized powder into distilled water, mixing, dissolving, sterilizing at 95-125 deg.C for 5-20 min, and cooling.

The preferred proportion of sucrose in skim milk is 1-7% by mass; preferably 3-5%; more preferably 4%.

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

The preferable fermentation time is 6-18 h; preferably 9-15 h; 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 is higher. For example, when the inoculum size is too small, the propagation rate of the strain is slow, so that the number of viable bacteria in the finally obtained fermented milk is lower than the preferable range of the inoculum size. For another example, when the concentration of sorghum stalks is lower than the preferred range, the amount of substances stimulating the proliferation of the strains is less, and the number of viable bacteria in the fermented milk is also reduced.

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

Furthermore, the viable count of the lactobacillus plantarum CGMCC NO.0847 in the fermented milk is more than 5x10⁸cfu/mL。

Furthermore, the fermented milk has good flavor and no peculiar smell. The taste of the fermented milk is better than that of other lactobacillus plantarum fermented milks which are also 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: mixing plant milkDissolving lyophilized powder of Bacillus CGMCC NO.0847 in small amount of sterile distilled water, taking out a loop by using an inoculating loop, streaking on MRS solid culture medium (purchased from Merck Co., USA), performing anaerobic culture at 37 ℃ for 24h, taking out a single colony by using the inoculating loop, putting the single colony into 10mL MRS liquid culture medium (purchased from Merck Co., USA), uniformly dispersing the colony in the liquid culture medium by using a vortex oscillator, performing anaerobic culture at 37 ℃ for 24h, taking out the colony, inoculating the single colony into the MRS liquid culture medium (purchased from Merck Co., USA) in an inoculation amount of 2% (v/v), performing anaerobic culture at 37 ℃ for 24h, centrifuging the culture at 15,000rpm for 10min, discarding supernatant, washing thallus with sterile distilled water for 2 times, suspending with sterile distilled water of the original culture volume to obtain seed for fermentation, wherein the bacterial concentration of the seed liquid is 1x10⁹cfu/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

Lactobacillus plantarum CGMCC NO.0847 seeds are aseptically inoculated into skim milk containing 4% (w/w, mass percent, the same below) of sucrose, 4% (w/w, mass percent, the same below) of sorghum straw and 8% (w/w, mass percent, the same below) of skim milk powder in an inoculation amount of 3% (v/v, the volume percent of the seed liquid accounts for the fermentation broth, and the same below), and the skim milk A is obtained after anaerobic culture at 37 ℃ for 12 hours.

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

The lactobacillus plantarum CGMCC NO.0847 seed is aseptically inoculated into skim milk containing 7 percent (w/w) of sucrose, 1 percent (w/w) of sorghum straw and 12 percent (w/w) of skim milk powder according to the inoculation amount of 1 percent (v/v), and is anaerobically cultured at 42 ℃ for 18h to obtain the fermented milk B.

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

The lactobacillus plantarum CGMCC NO.0847 seed is aseptically inoculated into skim milk containing 1% (w/w) of sucrose, 8% (w/w) of sorghum straw and 3% (w/w) of skim milk powder in an inoculation amount of 5% (v/v), and is anaerobically cultured for 6 hours at 26 ℃ to obtain the fermented milk C.

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

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, and carrying out anaerobic culture at 40 ℃ for 15h to obtain fermented milk 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

Inoculating Lactobacillus plantarum CGMCC NO.0847 seed with the 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, and anaerobically culturing at 30 ℃ for 9h to obtain fermented milk E.

Effect example 1Fermented milk viable bacteria detection

Viable bacteria counts were made for the lactobacillus plantarum fermented milk products A, B, C, D and E prepared in examples 1-5 above, and the results are shown in table 1.

TABLE 1 Lactobacillus plantarum fermented Lactobacillus count results

As shown in Table 1, the viable count of the lactobacillus plantarum fermented milk prepared by the method in the technical scheme of the invention is stably maintained at 5X10⁸CFU/mL or more.

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 3.1X 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 to sorghum straw juice for fermentation, lactobacillus plantarum CGMCC NO.0847 has certain growth effect (the multiplication rate is 4 times), but the multiplication effect is that sorghum straw is containedThe component skim milk is most remarkable (the proliferation rate is 26.7 times), and the ability of the sorghum straw juice to promote the proliferation of lactobacillus plantarum in the skim milk 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 the following lactobacillus plantarum fermented milks prepared by different methods, and the viable count in the fermented milks obtained from each group is shown in table 3.

TABLE 3 viable count of Lactobacillus plantarum fermented milks 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 are adjusted to be out of the preferable ranges, lactobacillus plantarum CGMCC No.0847 can still obtain partial proliferation growth in skim milk, but the proliferation effect is obviously reduced.

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 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 operations are 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

Inoculating Lactobacillus plantarum CGMCC NO.0847 seed 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 component (or soybean milk component), and performing anaerobic culture at 37 ℃ for 12h to obtain corresponding Lactobacillus plantarum fermented milk.

3. Viable count comparison

The lactobacillus plantarum fermented milks prepared in the above-described manner were counted, and the results are shown in table 4.

TABLE 4 viable count results for Lactobacillus plantarum fermented milks

As can be seen from table 4, the viable count of the fermented milk containing the sorghum straw component was higher than that of the fermented milk containing the soybean milk component at the same addition amount (4%), indicating that the sorghum straw juice had a better ability to promote the proliferation of lactobacillus plantarum in skim milk than soybean milk.

4. Comparison of product taste with preference

Taking the lactobacillus plantarum fermented milk 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 nutritional items of the fermented milk products were individually scored, each full score was 25, the average score and the total score thereof were calculated, and the statistical results were 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 containing sorghum straw component has a much higher score than the fermented milk containing soybean milk component because the former has a good flavor and no off-flavor, while the latter soybean milk component has a significant "fishy smell" after being fermented by microorganisms, so the former is more favored. The above-mentioned difference in product flavor directly resulted in a great difference in the preference of the product, as most of the testers (34 persons) showed that the fermented milk containing the sorghum stalk component was preferred, while none of them preferred the fermented milk containing the soymilk component, and on the contrary, more persons (38 persons) did not prefer the fermented milk containing the soymilk component.

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

The lactobacillus plantarum fermented milk provided by the invention and the preparation method thereof 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.