WO2023169393A1

WO2023169393A1 - Method for preparing fermented milk with live bacteria at normal temperature

Info

Publication number: WO2023169393A1
Application number: PCT/CN2023/079997
Authority: WO
Inventors: 金丽娜; 付永刚; 巴根纳; 樊启程; 罗俊溢
Original assignee: 内蒙古伊利实业集团股份有限公司
Priority date: 2022-03-07
Filing date: 2023-03-07
Publication date: 2023-09-14
Also published as: CN116762858A

Abstract

A method for preparing a fermented milk with live bacteria at normal temperature. The method comprises the following steps: fermenting a fermentation base material with lactose-negative bacteria other than Lactobacillus rhamnosus as fermenting bacteria, pasteurizing the obtained fermentation product, and then adding Lactobacillus rhamnosus to obtain the fermented milk with live bacteria at room temperature, wherein proliferative factors other than lactose are added to the fermentation base material; or inoculating the fermentation base material with lactose-negative bacteria other than Lactobacillus rhamnosus and Lactobacillus rhamnosus, and then performing fermentation to obtain the fermented milk with live bacteria at room temperature, wherein proliferative factors other than lactose are added to the fermentation base material.

Description

A method for preparing fermented milk with live bacteria at room temperature

This application claims priority to the Chinese patent application with application number 202210224369.5 filed with the State Intellectual Property Office of China on March 07, 2022, the entire content of which is incorporated into this application by reference.

Technical field

The invention relates to the technical field of dairy products, specifically a method for preparing fermented milk with live bacteria at room temperature.

Background technique

Fermented milk is a dairy product popular among consumers, with rich nutritional value and unique flavor. Low-temperature fermented milk refers to fermented milk that has a short shelf life and must be kept under refrigerated conditions during transportation and sales. Room-temperature fermented milk is fermented milk that is pasteurized again after fermentation. It has no viable bacteria and can therefore be stored at room temperature. ,transportation. Although room-temperature fermented milk can be stored at room temperature for a long time, there are no live bacteria in the product, and the benefits brought by fermented milk to the human body no longer exist.

The prior art discloses a variety of fermented milk beverages containing live bacteria. For example, Chinese patent CN101273736A discloses a method for preparing a fermented milk beverage that maintains a high number of viable bacteria at room temperature by adding rhamnose milk to the fermented milk beverage. Bacillus ATCC 53103 has prepared fermented milk beverages containing live bacteria. However, on the one hand, this method can only prepare fermented milk beverages containing live bacteria, and cannot prepare fermented milk containing live bacteria. On the other hand, the fermented milk beverages prepared by it During storage at room temperature, the number of active bacteria and the pH value of the product decrease rapidly.

Contents of the invention

In view of this, the object of the present invention is to provide a method for preparing fermented milk with live bacteria at room temperature. The method provided by the invention can prepare fermented milk at room temperature containing live bacteria, and when stored at room temperature for 6 months, the number of live bacteria in the product, There was no significant change in pH and acidity.

The invention provides a method for preparing fermented milk with live bacteria at room temperature, which includes the following steps:

The fermentation base material is fermented using lactose-negative bacteria other than Lactobacillus rhamnosus as fermentation bacteria, and Lactobacillus rhamnosus is added to the obtained fermentation product after pasteurization to obtain room-temperature live bacteria fermented milk;

Proliferation factors other than lactose are added to the fermentation base material.

The fermentation base material is inoculated with lactose-negative bacteria other than Lactobacillus rhamnosus and Lactobacillus rhamnosus and then fermented to obtain room-temperature viable bacteria fermented milk;

Chinese patent CN101273736A discloses a method for preparing fermented milk that maintains a high viable bacterial count at room temperature. It uses Lactobacillus rhamnosus ATCC 53103 as the fermenting bacteria, and at the same time adds lactose that can be utilized by the Lactobacillus rhamnosus. Monosaccharides or disaccharides are used as proliferation factors for fermentation. Lactobacillus rhamnosus ATCC 53103 does not ferment lactose and does not produce lactic acid. Therefore, the pH value at the end of fermentation can be controlled by controlling the amount of proliferation factors, thereby effectively controlling the post-acidification of fermented milk. The fermented milk can be stored at room temperature for a long time and maintain a high viable bacterial count. However, the fermentation speed of Lactobacillus rhamnosus ATCC 53103 is slow, and it generally requires more than 12 hours of fermentation to reach the fermentation end point, and its viable bacterial count is difficult to maintain. If stored at room temperature for about 28 days, the viable bacterial count will decrease by 2 orders of magnitude; in addition, , the fermented milk prepared with Lactobacillus rhamnosus ATCC53103 as the fermentation bacteria has poor flavor and taste.

Based on this, the inventor of the present application creatively discovered that using lactose-negative bacteria other than Lactobacillus rhamnosus as fermentation bacteria and Lactobacillus rhamnosus as live bacteria can prepare room-temperature fermented milk containing live bacteria, which not only has a short fermentation time , the taste and flavor are good, and the fermented milk has no obvious changes in its pH value, acid value and viable bacterial count when stored at room temperature for 6 months.

In the present invention, lactose-negative bacteria refer to strains that do not ferment lactose but ferment other monosaccharides or disaccharides, such as Lactobacillus rhamnosus, Ch. Acidifix ^TM 1.0, Chr. Hansen's wait. The present invention uses lactose-negative bacteria other than Lactobacillus rhamnosus as fermentation bacteria, which can shorten the fermentation time, make the taste and flavor of the fermented milk good, and is conducive to controlling the pH value and viable bacteria of the fermented milk when it is stored at room temperature. There were no significant changes in parameters such as number and acidity. In one embodiment, the lactose-negative bacteria as fermentation bacteria are selected from Chr. Hansen's Acidifix ^™ 1.0.

Lactobacillus rhamnosus is a strain that maintains the number of active bacteria in fermenting milk. It is also a lactose-negative bacterium, that is, it does not ferment lactose. In one embodiment, the Lactobacillus rhamnosus is selected from Chr.

In the embodiment of the present application, Lactobacillus rhamnosus can be added to the fermented milk to maintain the number of viable bacteria after the fermentation is completed; it can also be added to the fermentation base material at the same time as the fermentation bacteria for fermentation. Due to the fermentation speed of Lactobacillus rhamnosus Slower, other lactose negative bacteria e.g. Acidifix ^TM 1.0 and other fermentation speeds are faster, Lactobacillus rhamnosus exists mainly as active bacteria rather than fermentative bacteria.

In one embodiment, when lactose-negative bacteria other than Lactobacillus rhamnosus and Lactobacillus rhamnosus are inoculated into the fermentation base material for fermentation, the fermentation speed of lactose-negative bacteria other than Lactobacillus rhamnosus is faster than that of Lactobacillus rhamnosus. Lactobacillus lanceosus.

The fermentation base material includes a proliferation factor, which is used to control the start and stop of fermentation by lactose-negative bacteria other than Lactobacillus rhamnosus. By adjusting the content of proliferation factors in the fermentation base material, lactose-negative bacteria other than Lactobacillus rhamnosus can complete fermentation. In one embodiment, the proliferation factor is selected from the group consisting of glucose, fructose, galactose, arabinose, ribose, mannose, rhamnose, fucose, tagatose, sucrose, maltose, cellobiose, trehalose, At least one of melezitose, gentiobiose, acetylglucosamine and white sugar. In one embodiment, the proliferation factor is selected from white sugar or glucose. In one embodiment, the added amount of the proliferation factor is 0.6wt% to 1.2wt%. In one embodiment, the added amount of the proliferation factor is 0.7wt% to 1.0wt%.

The fermentation base material also includes: milk raw materials; and optionally flavoring agents, stabilizers, protein ingredients and water. Among them, milk raw materials, as the main base material for fermentation, are rich in proteins, minerals, growth factors and other nutrients. On the one hand, they provide carbon sources, nitrogen sources and trace elements for the growth of microbial fermentation. On the other hand, they give yogurt silky smoothness. Taste and texture and provide various nutrients necessary for the human body. In one embodiment, the milk raw material includes at least one of animal-based milk raw material or plant-based milk raw material, wherein the animal-based milk raw material includes but is not limited to raw cow milk, raw goat milk, raw camel milk or corresponding milk powder preparation Reconstituted milk, etc.; plant-based milk raw materials include but are not limited to soy milk or oat milk, etc.

Protein ingredients are nutritional food supplements that can increase the protein content in fermented base materials, making fermented milk have higher nutritional value and quality. In one embodiment, the protein ingredients include but are not limited to one or more of whey protein, milk protein, casein, soy protein isolate, soy protein concentrate, pea protein, peanut protein, walnut protein and coconut milk. kind.

The purpose of flavoring agents is to provide flavor, increase the soluble solid content of fermented milk, and achieve good palatability of fermented milk. The flavoring agents include, but are not limited to, sweeteners, flavors, etc. except for proliferation factors. In one embodiment, the flavoring agent is selected from sweetening sugar alcohols, including but not limited to isomaltulose, maltitol, erythritol, xylitol, galactitol, mannitol, sorbose Alcohol etc.

Stabilizers can evenly distribute fermented milk protein molecules in the fermented milk system, effectively improve protein flocculation, and achieve a thicker feel and stable state of the product. In one embodiment, stabilizers include, but are not limited to, pectin, agar, gellan gum, starch, carrageenan, gelatin, xanthan gum, diacetyl tartaric acid mono- and diglycerides, Mono- and diglyceryl fatty acid esters, acetylated distarch phosphate, hydroxypropyl distarch phosphate, citrus fiber, etc. In one embodiment, the combination of multiple stabilizers can improve the coagulation degree of fermented milk, such as the combination of agar, pectin, gellan gum and diacetyl tartaric acid mono- and diglycerides.

In the present invention, milk raw materials are first standardized, protein components, proliferation factors, stabilizers, flavors and other mixed materials are added, and the fermentation base material is obtained after homogenization, sterilization and cooling. Specifically, the present invention first adds protein components, a part of proliferation factors, stabilizers, flavors, etc. to a part of the standardized milk raw materials for processing, and then adds a second part of the standardized milk raw materials and the remaining part of the proliferation factors to continue the processing. ingredients, finally add the remaining milk ingredients and mix evenly. The uniformly mixed feed liquid is vacuum degassed, homogenized, sterilized and cooled to obtain the fermentation base material. In one embodiment, the vacuum degassing temperature is 50 to 65°C, and the degassing vacuum degree is -40 to -70 kpa. In one embodiment, the homogenization is two-stage homogenization. First, adjust the second level to make the pressure gauge indicate 30 bar, and then adjust the first level to make the pressure gauge indicate 160±5 bar. The homogenization temperature is 50-60°C. In one embodiment, the sterilization is 132±1°C/4s or 121±1°C/60s. In one embodiment, the cooling is cooling to 39-43°C.

In one embodiment, the fermentation base material includes:

80% to 99% milk raw materials;

0.6wt%～1.2wt% proliferation factor;

0~2% protein ingredients;

0 to 12% flavoring agent;

0~3% stabilizer;

remaining water.

In one embodiment, the fermentation base material includes:

80% to 99% milk raw materials;

0.8wt%～1.0wt% proliferation factor;

0~2% protein ingredients;

0 to 12% flavoring agent;

0~3% stabilizer;

remaining water.

After the fermentation base material is obtained, fermentation bacteria are inoculated into it. As mentioned above, the fermentation bacteria are lactose-negative bacteria other than Lactobacillus rhamnosus, preferably Acidifix ^™ 1.0. In one embodiment, the amount of lactose-negative bacteria added is 80 to 150 U/t. In one embodiment, the amount of lactose-negative bacteria added is 100~120U/t.

In one embodiment, the fermentation is carried out at 38-42°C until the pH is reduced to below 4.5, the acidity is titrated to 72°T and then demulsified, and after pasteurization, Lactobacillus rhamnosus is added under sterile conditions. , filling, you can get room temperature fermented milk with high viable bacteria count.

In one embodiment, the pasteurization temperature is 75°C to 80°C and the pasteurization time is 20 to 30 seconds. In one embodiment, the pasteurization temperature is 77°C and the pasteurization time is 25 seconds.

In one embodiment, Lactobacillus rhamnosus is selected from Chr. Hansen's In one embodiment, the added amount of Lactobacillus rhamnosus is 1.0×106CFU/g to 1.0×108CFU/g. In one embodiment, the added amount of Lactobacillus rhamnosus is 5.0×106CFU/g to 1.0×108CFU/g.

In the plan of adding fermentation bacteria and Lactobacillus rhamnosus at the same time, lactose-negative bacteria other than Lactobacillus rhamnosus and Lactobacillus rhamnosus as fermentation bacteria are added to the fermentation base material at the same time to ferment until the pH decreases. When the acidity is lower than 4.5, titrate the acidity to 72°T and then perform emulsification and filling to obtain room-temperature fermented milk with a high number of viable bacteria.

The inventor of the present application creatively discovered that using lactose-negative bacteria other than Lactobacillus rhamnosus as fermentation bacteria and Lactobacillus rhamnosus as live bacteria to prepare room-temperature fermented milk containing live bacteria, whether fermentation is performed first and then rhamnosus is added Lactobacillus saccharus, or adding fermentation bacteria and Lactobacillus rhamnosus at the same time, can shorten the fermentation time and complete the fermentation within 7 to 8 hours; and can obtain fermented milk with good taste and flavor. The most important thing is that by adding proliferation factors to the fermentation base material and controlling the fermentation end point, the fermented milk can be stored at room temperature for 6 months without significant changes in pH value, acidity and viable bacterial count.

In the method provided by this application, lactose-negative bacteria other than Lactobacillus rhamnosus are used as fermentation bacteria to ferment the milk raw materials, without consuming lactose and without producing carbon sources available for Lactobacillus rhamnosus, thereby controlling rhamnose. Lactobacillus fermentation produces acid, which stabilizes the post-acidity of Lactobacillus rhamnosus at room temperature and has a long shelf life, effectively controls the post-acidity, and obtains fermented milk with a stable taste.

Detailed ways

The preparation method of the room-temperature live bacterial fermented milk provided by the present invention will be described in detail below with reference to the examples.

Example 1

Fermented milk was prepared according to the formula shown in Table 1. Table 1 is the formula for preparing fermented milk in Example 1 and Comparative Example 1 of the present invention.

Table 1 Formulas for preparing fermented milk in Example 1 and Comparative Example 1 of the present invention

Among them, add The amount is 0.02% of the fermentation base material. After addition, the number of LGG viable bacteria in the fermentation base material is 5.0×10 ⁶ CFU/g.

The preparation method is as follows:

Standardized milk preparation: Separate raw milk at 60°C, remove mechanical impurities and standardize the fat; homogenize the fat-standardized milk at 60°C, 100±5bar, and then pre-sterilize at 75°C 15s, get standardized milk;

Preparation of fermentation base material: Heat standardized milk accounting for 50% of the ingredients to 55°C, first add whey protein powder to the standardized milk, and use chemical equipment with mixing, dispersing, shearing, and emulsifying effects to chemicalize the material liquid. Material, make the material liquid become a uniform and dispersed mixture, the temperature of the material is maintained at 55°C, and the time of the material is 10 minutes; then, at 55°C, erythritol, agar, pectin, diacetyl tartaric acid mono- and diglycerides, Add gellan gum, white sugar and glucose into the mixing system. Keep the mixing temperature at 55°C and the mixing time at 20 minutes. After cooling, pour the liquid into another batching tank, and then pour the remaining ingredients into the above with milk. Mix evenly in the feed liquid, then perform degassing (degassing temperature 55°C, degassing vacuum degree 10kpa), homogenization (220bar), base material sterilization (115°C, 120s), and pump into the fermentation tank to prepare for fermentation.

Fermentation: The fermentation temperature is maintained at 40°C. When the remaining material liquid in the batching tank is 40%, turn on the stirring at full speed. Hansen purchased from Chr. Hansen was added through a laminar flow hood. Acidifix ^TM 1.0, start timing from the end of base material feeding, stop stirring after 10 minutes, the mixing effect is subject to the absence of large pieces of bacteria powder gathering in the fermentation tank, let it ferment quietly, start to detect the pH after 7 hours of fermentation, and wait until the pH of the yogurt drops. to below 4.5, titrate the acidity to 72°T, start stirring to break the emulsification, stir at a speed of 25 rpm, and stir for 2 minutes;

Yogurt pasteurization: Yogurt feeding temperature is 30°C, and yogurt pasteurization conditions are 77°C/25s. The outlet temperature is 40℃ and stored in sterile tanks;

Sterile addition of Lactobacillus rhamnosus (Purchased from Chr. Hansen);

Filling: filling temperature is 20~25℃.

The difference in the preparation method of Comparative Example 1 is that fermentation bacteria use The pH will be tested after 18 hours of fermentation, and the yogurt will be filled directly without pasteurization.

The results show that after 7 to 8 hours of fermentation in Example 1, the pH of the fermented milk reaches 4.4-4.5 and the acidity reaches 70-75°T; while in Comparative Example 1, it takes 18 to 22 hours to ferment the pH of the fermented milk to 4.4-4.5 and the acidity to 70-70. 75°T.

Sensory evaluation was performed on the yogurt prepared in Example 1 and Comparative Example 1. The results are shown in Table 2. Table 2 is the sensory evaluation results of the yogurt prepared in Example 1 and Comparative Example 1 of the present invention. The sensory evaluation method is as follows:

Evaluation process: An evaluation team of more than or equal to 50 people will score the degree of curdling, fluidity, fineness and oral retention on a 10-point scale. 1 means I don’t like it very much, 10 means I like it very much, and the final score is The average output result of 50 people's ratings.

Degree of curdling: The protein in milk gradually approaches the isoelectric point of the protein during the process of lowering the pH. The spatial configuration of the protein (mainly the tertiary structure and quaternary structure) changes, and hydrogen bonds associate to form cross-linked structures. Spatial network structure, proteins aggregate with each other. The macroscopic manifestation is curdled milk.

Fluidity: the flow characteristics of yogurt;

Delicacy: Yogurt is fermented for a long time, with repeated curdling and bumping to break the emulsification, resulting in water separation and agglomeration, resulting in an unsmooth feeling when tasting.

Oral retention: How long yogurt stays in the mouth.

Table 2 Sensory evaluation results of yogurt prepared in Example 1 and Comparative Example 1 of the present invention

It can be seen from Table 2 that the fermented milk obtained by fermentation in the examples of the present application has higher scores than the yogurt prepared in Comparative Example 1 in terms of degree of curdling, fineness and retention in the mouth.

The yogurt obtained in Example 1 was stored at room temperature, 30°C, 37°C and 45°C for 6 months respectively, at the initial stage of storage (W0, the detection time was actually the third day after sample preparation), one week (W1), two Week (W2), three weeks (W3), four weeks (W4), five weeks (W5), six weeks (W6), seven weeks (W7), eight weeks (W8), eleven weeks (W11), sixteen weeks The pH value of the yogurt was tested at (W16), seventeen weeks (W17), twenty weeks (W20), twenty-two weeks (W22) and twenty-eight weeks (W28). The results are shown in Table 3. Table 3 is the basis. The pH value detection results of yogurt provided in Example 1 of the invention.

Table 3 pH value detection results of the yogurt provided in Example 1 of the present invention

It can be seen from Table 3 that the pH value of the normal temperature yogurt prepared by the present invention does not decrease significantly when stored at normal temperature, 30°C, 37°C and 45°C for 6 months.

The yogurt obtained in Example 1 was stored at 4°C and normal temperature for 6 months respectively, at the initial stage of storage (D3), five days (D5), nine days (D9), sixteen days (D16), and twenty-two days (D16). The pH value of the yogurt was tested at D22), two months (M2), three months (M3), four months (M4), five months (M5) and six months (M6). The results are shown in Table 4. Table 4 shows the pH value detection results of the yogurt provided in Comparative Example 1 of the present invention.

Table 4 pH value detection results of the yogurt provided in Comparative Example 1 of the present invention

It can be seen from Table 4 that the pH value of the yogurt prepared in Comparative Example 1 dropped rapidly at room temperature.

The yogurt obtained in Example 1 and Comparative Example 1 was stored at room temperature for 6 months respectively, at the initial stage of storage (M0, the detection time was actually the third day after sample preparation), one month (M1), and two months (M2). ), three months (M3), four months (M4), five months (M5) and six months (M6) to detect the number of viable bacteria and acidity of the yogurt. The results are shown in Table 5 and Table 6, Table 5 Table 6 is the test result of the viable bacterial count of the yogurt provided in Example 1 and Comparative Example 1 of the present invention. Table 6 is the acidity test result of the yogurt provided in Example 1 and Comparative Example 1 of the present invention.

Table 5 Test results of viable bacteria count of the yogurt provided in Example 1 and Comparative Example 1 of the present invention

Table 6 Acidity test results of the yogurt provided by Example 1 and Comparative Example 1 of the present invention

It can be seen from Table 5 and Table 6 that the number of viable bacteria and acidity of the yogurt prepared by the method provided in the embodiments of the present application are maintained well at room temperature, and neither changes significantly.

Example 2

Fermented milk was prepared according to the formula shown in Table 7. Table 7 is the formula for preparing fermented milk in Example 2 of the present invention.

Table 7 Formula for preparing fermented milk in Example 2 of the present invention

The preparation method is as follows:

Preparation of fermentation base material: Heat the fresh milk accounting for 50% of the ingredients to 55°C, first add whey protein to the fresh milk, and use chemical equipment with mixing, dispersing, shearing, and emulsifying effects to dissolve the material liquid. , so that the material liquid becomes a uniform and dispersed mixture, the temperature of the material is maintained at 55°C, and the time of the material is 10 minutes; then white sugar, isomaltulose, erythritol and modified starch are added to the material system at 55°C. The temperature of the material is maintained at 55°C, and the time of the material is maintained at 20 minutes. After cooling, the material liquid is poured into another ingredient tank, and then the remaining ingredients are poured into the above material liquid with milk and mixed evenly, and then degassed (degassing) Temperature 55℃, degassing vacuum degree 10kpa), homogenization (220bar), base material sterilization (115℃, 120s), pumped into the fermentation tank to prepare for fermentation.

Fermentation: The fermentation temperature is maintained at 40°C. When 40% of the remaining material liquid in the batching tank is 40%, stir is turned on at full speed and the mixture purchased from Chr. Hansen is added through the laminar flow hood. Acidifix ^TM 1.0 and Start timing after the base material is fed. Stop stirring after 10 minutes. The mixing effect is subject to the absence of large accumulation of bacterial powder in the fermentation tank. Let it ferment quietly. Start testing the pH after 7 hours of fermentation. When the pH of the yogurt drops below 4.5, Titrate the acidity to 72°T, start stirring to break the emulsification, stir at a speed of 25 rpm, and stir for 2 minutes;

Filling: filling temperature is 20~25℃.

Comparative example 2

The difference from Example 2 is that the fermentation strain is Chr. Hansen F-DVS G089 (including Lactobacillus bulgaricus and Streptococcus thermophilus), and the addition amount is 150U/t. After the fermentation is completed, the obtained yogurt is pasteurized. Yogurt was pasteurized at 77°C/25s, and then Chr. Hansen was added aseptically. Filling is carried out at 20~25℃.

The yogurt obtained in Example 2 was stored at 4°C, 25°C, 37°C and 45°C for 1 to 8 months respectively, at the initial stage of storage (D3), one week (W1), two weeks (W2), and three weeks ( W3), four weeks (W4), five weeks (W5), six weeks (W6), eight weeks (M2), ten weeks (W10), twelve weeks (W12), four months (M4), five months ( M5), six months (M6) and thirty-two weeks (W32), the viable bacterial count, pH value and titratable acidity (TA) of the yogurt were tested. The results are shown in Table 8, Table 9, Table 10 and Table 11. Table 8 is the test result of the yogurt provided in Embodiment 2 of the present invention at 4°C. Table 9 is the test result of the yogurt provided in Embodiment 2 of the present invention at 25°C. Table 10 is the test result of the yogurt provided in Embodiment 2 of the present invention at 25°C. Test results at 37°C. Table 11 shows the test results of the yogurt provided in Example 2 of the present invention at 45°C.

Table 8 Test results of the yogurt provided in Example 2 of the present invention at 4°C

Table 9 Test results of the yogurt provided in Example 2 of the present invention at 25°C

Table 10 Test results of the yogurt provided in Example 2 of the present invention at 37°C

Table 11 Test results of the yogurt provided in Example 2 of the present invention at 45°C

The yogurt obtained in Example 2 was stored at 25°C for 6 months, respectively at four weeks (W4), five weeks (W5), eight weeks (M2), 12 weeks (W12), four months (M4), and five weeks. The number of viable bacteria, pH value and acidity of the yogurt were tested at one month (M5) and six months (M6). The results are shown in Table 12 and Table 13. Table 12 is the yogurt provided in Comparative Example 2 of the present invention at 25°C. Test results, Table 13 shows the test results of the yogurt provided in Comparative Example 2 of the present invention at 37°C.

Table 12 Test results of the yogurt provided in Comparative Example 2 of the present invention at 25°C

Table 13 Test results of the yogurt provided in Comparative Example 2 of the present invention at 37°C

It can be seen from Tables 8 to 13 that the yogurt fermented by the method provided in this application has little change in the number of viable bacteria, pH value and acidity when stored at room temperature for 6 months.

Sensory evaluation was performed on the yogurt prepared in Example 2 and Comparative Example 2. The results are shown in Table 14. Table 14 is the sensory evaluation results of the yogurt prepared in Example 2 and Comparative Example 2 of the present invention. The sensory evaluation method is as follows:

Evaluation process: An evaluation team of more than or equal to 50 people will evaluate the sweetness and sourness and organizational status according to a 10-point scale. 1 means I don't like it very much, and 10 means I like it very much. Finally, the average of the ratings of 50 people is used to output the result.

Sweet and sour feeling: Whether the sweet and sour ratio of yogurt is harmonious;

Organization status: visual experience of seeing yogurt and output preference;

Evaluation: the most frequently occurring adjective;

Table 14 Sensory evaluation results of yogurt prepared in Example 2 and Comparative Example 2 of the present invention

Example 3

Fermented milk was prepared according to the formula shown in Table 15. Table 15 is the formula for preparing fermented milk in Example 3 of the present invention.

Table 15 Formula for preparing fermented milk in Example 3 of the present invention

Among them, add The amount is 0.02% of the fermentation base material. After addition, the number of LGG viable bacteria in the fermentation base material is 5.0×10 ⁶ CFU/g;

The preparation process is as follows:

1. Separate pre-sterilized milk through RO membrane filtration equipment to obtain RO retentate and RO permeate.

Recommended value of protein content in RO retentate (%): 5.0≤protein≤5.2

Recommended value of fat content in RO retentate (%): 5.7≤fat≤6.4

2. Heat the membrane filtration RO retentate that accounts for 50 to 55% of the fermented milk ingredients to 60 to 65°C, add whey protein powder and stabilizers except pectin and agar powder under stirring conditions, and mix the materials. The temperature is maintained at 60~65℃, the mixing time is kept at 15~20 minutes, the mixing time is uniform and the volume is constant.

3. The base material is homogenized at 30/160bar, sterilized at 132℃/4s, and placed in a fermentation tank for constant temperature fermentation at 40℃. Use of fermentation strains Acidifix ^TM 1.0, fermented to pH below 4.5, acidity Fermentation is completed when the temperature is above 95°T and stored.

4. Prepare B2 glue: Heat the RO permeate, which accounts for 91 to 92% of the ingredients of B2 glue, to 70-75°C, add pectin to obtain B2 glue, and use a chemical with mixing, dispersing, shearing, and emulsifying effects. Feeding equipment, the mixing time is 15-20 minutes, so that the feed liquid becomes a mixture that is evenly dispersed and has no visible particles. After sterilization at 115-121℃/40-45s, it is cooled to 40-45℃ and mixed with fermented milk. The mixing ratio is 5.5 :1.

5. Prepare B3 glue: Heat the RO permeate, which accounts for 83~84% of the B3 glue ingredients, to 70~75°C, add agar and mix well to obtain B3 glue. After sterilization at 115~121°C/40~45s Sterile and temporarily store at 35-40°C, mix with prepared fermented milk and B2 glue in a ratio of 9:1.

6. Sterile addition

7. Filling: Fill into sterile cups at 35-40°C to prepare sterile cup stirred yogurt.

The yogurt obtained in Example 3 was stored at 25°C for 6 months, respectively after preparation (D0), the third day (D3), the second month (M2), four months (M4) and six months. (M6) Detect the number of viable bacteria and pH value of the yogurt. For the results, see Table 16 and Table 17. Table 16 is the detection result of the number of viable bacteria at 25°C for the yogurt provided in Example 3 of the present invention. Table 17 is the test result of the number of viable bacteria of the yogurt. Example 3 provides the pH value detection results of yogurt at 25°C.

Table 16 Test results of viable bacterial count of the yogurt provided in Example 3 of the present invention at 25°C

Table 17 pH value detection results of the yogurt provided in Example 3 of the present invention at 25°C

Among them, the commercially available yogurt is commercially available cup-packed low-temperature yogurt.

After comparison, Example 3 compares the number of lactic acid bacteria in commercially available cup yogurt. At normal temperature (25°C), the number of viable bacteria in the yogurt prepared in Example 3 is effectively maintained, while the number of viable bacteria in commercially available yogurt drops sharply after two months. There is basically no detection at the end; from a pH value point of view, the commercially available yogurt is severely sour, and the pH of 3.65 is severely acidic and unacceptable. The pH of the yogurt prepared in Example 3 dropped by 0.2 from the bottom line, and the decrease is acceptable.

The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person familiar with the technical field can, within the technical scope disclosed in the present invention, implement the technical solutions of the present invention. Equivalent substitutions or changes of the inventive concept thereof shall be included in the protection scope of the present invention.

Claims

A method for preparing fermented milk with live bacteria at room temperature, including the following steps:

The fermentation base material is fermented using lactose-negative bacteria other than Lactobacillus rhamnosus as fermentation bacteria, and Lactobacillus rhamnosus is added to the obtained fermentation product after pasteurization to obtain room-temperature live bacteria fermented milk;

Proliferation factors other than lactose are added to the fermentation base material.
A method for preparing fermented milk with live bacteria at room temperature, including the following steps:

The fermentation base material is inoculated with lactose-negative bacteria other than Lactobacillus rhamnosus and Lactobacillus rhamnosus and then fermented to obtain room-temperature viable bacteria fermented milk;

Proliferation factors other than lactose are added to the fermentation base material.
The preparation method according to claim 1 or 2, characterized in that the proliferation factor is selected from the group consisting of glucose, fructose, galactose, arabinose, ribose, mannose, rhamnose, fucose, tagatose, and sucrose. , at least one of maltose, cellobiose, trehalose, melezitose, gentiobiose, acetylglucosamine and white sugar, preferably white sugar.
The preparation method according to claim 3, characterized in that the added amount of the proliferation factor is 0.6wt% to 1.2wt%.
The preparation method according to claim 1 or 2, characterized in that the lactose-negative bacteria are selected from AcidifixTM 1.0;

The Lactobacillus rhamnosus is selected from
The preparation method according to claim 5, characterized in that the added amount of the lactose-negative bacteria is 80 to 150 U/t;

The added amount of Lactobacillus rhamnosus is 1.0×106CFU/g to 1.0×108CFU/g.
The preparation method according to claim 1 or 2, characterized in that the fermentation base material further includes: milk raw materials; and optionally flavoring agents, stabilizers, protein ingredients and water.
The preparation method according to claim 7, characterized in that the fermentation base material includes:

80% to 99% milk raw materials;

0 to 2% protein ingredients;

0 to 12% flavoring agent;

0~3% stabilizer;

remaining water.
The preparation method according to claim 8, wherein the milk raw material is selected from at least one of animal-based milk raw materials or plant-based milk raw materials;

The protein component is selected from one or more of whey protein, milk protein, casein, soy protein isolate, soy protein concentrate, pea protein, peanut protein, walnut protein and coconut milk;

The flavoring agent is selected from one or more types of isomaltulose, maltitol, erythritol, xylitol, galactitol, mannitol, sorbitol and flavors;

The stabilizer is selected from pectin, agar, gellan gum, starch, carrageenan, gelatin, diacetyl tartaric acid mono and diglycerides, mono and diglyceryl fatty acid esters, acetylated distarch phosphate, hydroxypropyl distarch phosphate One or more of ester, citrus fiber and xanthan gum.
Room-temperature live bacteria fermented milk prepared by the method according to any one of claims 1 to 9.