A preparation method of room-temperature live bacteria fermented milk

Abstract

The present invention provides a method for preparing room-temperature live bacteria fermented milk, comprising the following steps: inoculating lactose-negative bacteria other than Lactobacillus rhamnosus and Lactobacillus rhamnosus into a fermentation base, then filling the base, and obtaining room-temperature live bacteria fermented milk after fermentation; proliferation factors other than lactose are added to the fermentation base. The inventors of the present application creatively discovered that by 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, the fermentation time can be shortened, and fermented milk with good taste and flavor can be obtained. At the same time, by adding proliferation factors to the fermentation base and controlling the fermentation end point, the obtained fermented milk can be stored at room temperature for 6 months without significant changes in its pH value, acidity and live bacteria count.

Description

Technical Field

[0001] The invention relates to the technical field of dairy products, in particular to a method for preparing room-temperature live bacteria fermented milk. Background Art

[0002] Fermented milk is a popular dairy product with rich nutritional value and a unique flavor. Low-temperature fermented milk has a short shelf life and must be refrigerated throughout transportation and sales. Room-temperature fermented milk, on the other hand, is fermented and then pasteurized. It contains no live bacteria and can therefore be stored and transported at room temperature. While room-temperature fermented milk can be stored for extended periods at room temperature, the absence of live bacteria negates the benefits it provides.

[0003] 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 live bacteria count at room temperature. The method prepares a fermented milk beverage containing live bacteria by adding Lactobacillus rhamnosus ATCC 53103 to a fermented milk beverage. However, this method can only prepare a fermented milk beverage containing live bacteria, but cannot prepare fermented milk containing live bacteria. Furthermore, during storage at room temperature, the number of active bacteria and the pH value of the fermented milk beverage prepared by the method decrease rapidly. Summary of the Invention

[0004] In view of this, the object of the present invention is to provide a method for preparing room-temperature fermented milk containing live bacteria. The method provided by the present invention can prepare room-temperature fermented milk containing live bacteria, and the number of live bacteria, pH value and acid value in the product do not decrease significantly after being stored at room temperature for 6 months.

[0005] The present invention provides a method for preparing room-temperature live bacteria fermented milk, comprising the following steps:

[0006] Inoculating lactose-negative bacteria other than Lactobacillus rhamnosus and Lactobacillus rhamnosus into the fermentation base material and then filling the fermentation base material to obtain room-temperature live bacteria fermented milk after fermentation;

[0007] Proliferation factors other than lactose are added into the fermentation base.

[0008] Chinese patent CN101273736A discloses a method for preparing fermented milk that maintains a high viable cell count at room temperature. The method uses Lactobacillus rhamnosus ATCC 53103 as a fermenting bacterium and simultaneously adds a monosaccharide or disaccharide that can be utilized by Lactobacillus rhamnosus 53103, other than lactose, as a proliferation factor for fermentation. Lactobacillus rhamnosus ATCC 53103 does not ferment lactose and does not produce lactic acid. Therefore, by controlling the amount of proliferation factor to initiate fermentation and controlling the pH value at the fermentation endpoint, the post-acidification of the fermented milk can be effectively controlled, allowing the fermented milk to be stored at room temperature for a long time while maintaining a high viable cell count. However, Lactobacillus rhamnosus ATCC 53103 has a slow fermentation rate, generally requiring more than 12 hours to reach the fermentation endpoint, and its viable cell count is difficult to maintain. After about 28 days of storage at room temperature, the viable cell count decreases by two orders of magnitude. In addition, fermented milk prepared using Lactobacillus rhamnosus ATCC 53103 as a fermenting bacterium has a poor flavor and taste. Based on this, the inventors of the present application creatively discovered that room-temperature fermented milk containing live bacteria is prepared by using lactose-negative bacteria other than Lactobacillus rhamnosus as fermentation bacteria and Lactobacillus rhamnosus as live bacteria. Not only does it have a short fermentation time and good taste and flavor, but the fermented milk can also be stored at room temperature for 6 months without significant changes in pH value, acid value and live bacteria count.

[0009] 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, Chr. Hansen's Acidifix TM 1.0, Chr. Hansen's The present invention uses lactose-negative bacteria other than Lactobacillus rhamnosus as fermentation bacteria, which can shorten the fermentation time, make the fermented milk taste and have good flavor, and help control the pH value, viable cell count, acidity and other parameters of the fermented milk when stored at room temperature without significant changes. In one embodiment, the lactose-negative bacteria used as fermentation bacteria are selected from Chr. Hansen's Acidifix TM 1.0.

[0010] Lactobacillus rhamnosus is a strain that maintains the number of active bacteria in fermented 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. Hansen's

[0011] In the embodiment of the present application, Lactobacillus rhamnosus and fermentation bacteria are added to the fermentation base at the same time for fermentation. Since Lactobacillus rhamnosus ferments slowly, other lactose-negative bacteria such as Acidifix TM 1.0 and other fermentation speeds are faster, and Lactobacillus rhamnosus mainly exists as active bacteria rather than fermentation bacteria.

[0012] In one embodiment, when lactose-negative bacteria other than Lactobacillus rhamnosus and Lactobacillus rhamnosus are inoculated into a fermentation base for fermentation, the fermentation speed of the lactose-negative bacteria other than Lactobacillus rhamnosus is faster than that of Lactobacillus rhamnosus.

[0013] The fermentation base 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 the proliferation factor in the fermentation base, lactose-negative bacteria other than Lactobacillus rhamnosus can complete the fermentation. In one embodiment, the proliferation factor is selected from at least one of glucose, fructose, galactose, arabinose, ribose, mannose, rhamnose, fucose, tagatose, sucrose, maltose, cellobiose, trehalose, melezitose, gentiobiose, acetylglucosamine and white sugar. In one embodiment, the proliferation factor is selected from white sugar or glucose. In one embodiment, the addition amount of the proliferation factor is 0.6wt% to 1.2wt%. In one embodiment, the addition amount of the proliferation factor is 0.7wt% to 1.0wt%.

[0014] The fermentation base also includes: milk raw materials; and optionally flavoring agents, stabilizers, protein components and water. Among them, the milk raw materials, as the main fermentation base, are rich in various nutrients such as protein, minerals, growth factors, etc. On the one hand, they provide carbon sources, nitrogen sources and trace elements for the growth of microbial fermentation, and on the other hand, they give yogurt a silky taste and texture and provide various nutrients necessary for the human body. In one embodiment, the milk raw materials include at least one of animal-based milk raw materials or plant-based milk raw materials, wherein animal-based milk raw materials include but are not limited to raw cow's milk, raw goat's milk, raw camel's milk or reconstituted milk prepared from corresponding milk powder, etc.; plant-based milk raw materials include but are not limited to soy milk or oat milk, etc.

[0015] Protein ingredients are nutritional food supplements that can increase the protein content in the fermentation base, thereby enhancing the nutritional value and quality of the fermented milk. 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.

[0016] The purpose of flavoring agents is to provide flavor, increase the soluble solids content of fermented milk, and achieve good palatability. Such flavoring agents include, but are not limited to, sweeteners and flavorings, excluding growth factors. In one embodiment, the flavoring agents are selected from sweet sugar substitutes such as isomaltulose, maltitol, erythritol, xylitol, galactitol, mannitol, and sorbitol.

[0017] Stabilizers can make the fermented milk protein molecules evenly distributed in the fermented milk system, effectively improve protein flocculation, and achieve a thick 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 diglycerol 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.

[0018] The present invention first standardizes the raw milk material, then adds a protein component, growth factors, stabilizers, flavoring agents, and other ingredients to the mixture. The mixture is then homogenized, sterilized, and cooled to produce a fermentation base. Specifically, the present invention first adds the protein component, a portion of growth factors, stabilizers, and flavoring agents to a portion of the standardized raw milk material for homogenization. A second portion of the standardized raw milk material and the remaining growth factors are then added for further homogenization. Finally, the remaining raw milk material is added and mixed until uniformly mixed. The uniformly mixed liquid is then vacuum degassed, homogenized, sterilized, and cooled to produce the fermentation base. In one embodiment, the vacuum degassed temperature is 50-65°C, and the degassed vacuum level is -40 to -70 kPa. In one embodiment, the homogenization is a two-stage process, with the pressure gauge first adjusted to 30 bar, and then adjusted to 160±5 bar. The homogenization temperature is 50-60°C. In one embodiment, the sterilization is performed at 132±1°C / 4s or 121±1°C / 60s. In one embodiment, the cooling is performed to a temperature of 39-43°C.

[0019] In one embodiment, the fermentation base comprises:

[0020] 80% to 99% milk raw materials;

[0021] 0.6 wt% to 1.2 wt% of proliferation factor;

[0022] 0-2% protein ingredients;

[0023] 0-12% flavoring agent;

[0024] 0-3% stabilizer;

[0025] The remaining amount of water.

[0026] In one embodiment, the fermentation base comprises:

[0027] 80% to 99% milk raw materials;

[0028] 0.8 wt% to 1.0 wt% of proliferation factor;

[0029] 0-2% protein ingredients;

[0030] 0-12% flavoring agent;

[0031] 0-3% stabilizer;

[0032] The remaining amount of water.

[0033] After obtaining the fermentation base, fermentation bacteria and Lactobacillus rhamnosus are inoculated therein. As mentioned above, the fermentation bacteria are lactose-negative bacteria other than Lactobacillus rhamnosus, preferably Acidifix TM 1.0. In one embodiment, the amount of lactose-negative bacteria added is 80-150 U / t. In one embodiment, the amount of lactose-negative bacteria added is 100-120 U / t. In one embodiment, Lactobacillus rhamnosus is selected from Chr. Hansen In one embodiment, the amount of Lactobacillus rhamnosus added is 1.0×10 6 CFU / g or more. In one embodiment, the amount of Lactobacillus rhamnosus added is 1.0×10 6 CFU / g~1.0×10 9 In one embodiment, the amount of Lactobacillus rhamnosus added is 5.0×10 6 CFU / g~5.0×10 8 CFU / g.

[0034] The fermentation base and the bacterial strain are mixed evenly and then filled at a temperature of 20-25° C. After filling, fermentation is carried out to obtain solidified room-temperature fermented milk. In one embodiment, the fermentation is carried out at a temperature of 38-42° C.

[0035] The inventors of this application have creatively discovered that using lactose-negative bacteria other than Lactobacillus rhamnosus as fermenting bacteria, and using Lactobacillus rhamnosus as the live bacteria, to prepare room-temperature fermented milk containing live bacteria can shorten fermentation time and produce fermented milk with a good taste and flavor. Furthermore, by adding growth factors to the fermentation base and controlling the fermentation endpoint, the resulting fermented milk can be stored at room temperature for six months without significant changes in pH, acidity, or live bacterial count.

[0036] In the method provided in the present application, lactose-negative bacteria other than Lactobacillus rhamnosus are used as fermentation bacteria to ferment milk raw materials, without consuming lactose and producing a carbon source available for Lactobacillus rhamnosus, thereby controlling the acid production by Lactobacillus rhamnosus fermentation, achieving the post-acid stability of Lactobacillus rhamnosus at room temperature and for a long shelf life, effectively controlling the post-acidity, and obtaining fermented milk with a stable taste. DETAILED DESCRIPTION

[0037] The preparation method of room temperature live bacteria fermented milk provided by the present invention is described in detail below with reference to the examples.

[0038] Example 1

[0039] Fermented milk was prepared according to the formula shown in Table 1. Table 1 is the formula for preparing fermented milk in Example 1 of the present invention.

[0040] Table 1 Formula for preparing fermented milk in Example 1 of the present invention

[0041]

[0042] Among them, add The amount is 0.02% of the fermentation base, and the number of LGG viable bacteria in the fermentation base after addition is 5.0×10 6 CFU / g.

[0043] The preparation method is as follows:

[0044] Preparation of fermentation base: Heat fresh milk accounting for 50% of the ingredients to 55°C, first add whey protein to the fresh milk, and use a mixing, dispersing, shearing and emulsifying device to mix the liquid to make a uniform and dispersed mixture. The mixing temperature is maintained at 55°C and the mixing time is 10 minutes; then add white sugar, isomaltulose, modified starch and gelatin to the mixing system at 55°C, and the mixing temperature is maintained at 55°C for 20 minutes. After cooling, the liquid is pumped into another mixing tank, and the remaining ingredients are pumped into the above liquid with milk to mix evenly. Subsequently, deaeration (degassing temperature 55°C, degassing vacuum degree 10kPa), homogenization (220bar), base sterilization (115°C, 120s), and pumped into a sterile tank for filling.

[0045] Sterile addition: adding bacteria Acidifix TM 1.0 and

[0046] Filling: Filling temperature 20 ~ 25 ℃.

[0047] Ferment at 40°C for 7 to 8 hours to obtain coagulated fermented milk.

[0048] Comparative Example 1

[0049] The difference from Example 1 is that only LGG was added at a rate of 0.02%. After that, the number of viable bacteria in the fermentation base was 5.0×10 6 CFU / g.

[0050] The yogurt obtained in Example 1 was stored at 25° C., 37° C. and 45° C. for 1 to 7 months, and the viable cell count and pH value of the yogurt were detected at 6 hours (6 h), 7 hours (7 h), 9 hours (9 h), 12 hours (12 h), 16 hours (16 h), 72 hours (72 h), 96 hours (96 h), 120 hours (120 h), 144 hours (144 h), 168 hours (168 h), 336 hours (336 h), 20 days (D20), 30 days (D30), four weeks (W4), eight weeks (W8), twelve weeks (W12), four months (M4), five months (M5), six months (M6) and seven months (M7). The results are shown in Tables 2, 3, 4 and 5. Table 2 is the test results of the pH values ​​of the yogurt provided in Example 1 of the present invention stored at different temperatures, Table 3 is the test results of the yogurt provided in Example 1 of the present invention at 25°C, Table 4 is the test results of the pH values ​​of the yogurt provided in Comparative Example 1 of the present invention stored at different temperatures, and Table 5 is the test results of the yogurt provided in Comparative Example 1 of the present invention at 25°C.

[0051] Table 2 Detection results of pH value of yogurt provided by Example 1 of the present invention stored at different temperatures

[0052] 6h 7h 9h 10h 12h 16h 72h 96h 120h 144h 168h 336h D20 D30 37℃ 4.64 4.61 4.59 4.56 4.53 4.47 4.35 4.4 4.33 4.32 4.34 4.33 4.33 4.34 45℃ 4.7 4.66 4.66 4.65 4.58 4.49 4.37 4.33 4.39 4.35 4.34 4.34 4.34 4.35 25℃ / / 4.87 4.79 4.73 4.62 4.39 4.39 4.39 4.37 4.37 4.37 4.34 4.34

[0053] Table 3 Test results of yogurt provided by Example 1 of the present invention at 25°C

[0054]

[0055] Table 4 pH and acidity test results of yogurt provided by Comparative Example 1 of the present invention stored at different temperatures

[0056]

[0057] Table 5 Test results of yogurt provided in Comparative Example 1 of the present invention at 25°C.

[0058]

[0059] After the yogurts prepared in Example 1 and Comparative Example 1 were stored at room temperature for 3 months, a sensory evaluation was performed. The results are shown in Table 6. Table 6 shows the sensory evaluation results of the yogurts prepared in Example 1 and Comparative Example 1 of the present invention. The sensory evaluation method is as follows:

[0060] Evaluation process: An evaluation team of 50 or more people will score the sweetness and sourness, fullness of taste, and smoothness on a 10-point scale, with 1 point representing very dislike and 10 points representing very like. The final result is the average of the 50 scores.

[0061] Sweet and sour taste: whether the sweet and sour ratio of yogurt is harmonious;

[0062] Mouth fullness: The degree to which the yogurt fills the mouth and gives a full and rich feeling;

[0063] Smoothness: The yogurt has no grainy, astringent or sticky feeling when it enters the mouth.

[0064] Oral retention: how long yogurt stays in the mouth.

[0065] Table 6 Sensory evaluation results of yogurt prepared in Example 1 of the present invention and Comparative Example 1

[0066] Scoring sweet and sour Fullness of taste Smooth feeling Example 1 5 4 5 Comparative Example 1 2 2 4

[0067] As shown in Table 6, the sample prepared using Example 1 has a harmonious sweet and sour taste, is natural and mild, and has an acceptable taste change over the shelf life. It has no obvious sourness compared to the control example, and continues to become sour over the shelf life.

[0068] The sample prepared in the embodiment has a silky, full and rich texture, and has a unique texture of yogurt. The yogurt in the comparative example lacks the unique texture, has obvious acidity and lacks silkiness.

[0069] Example 2

[0070] 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.

[0071] Table 7 Formula for preparing fermented milk according to Example 2 of the present invention

[0072]

[0073]

[0074] Among them, add The amount is 0.02% of the fermentation base, and the number of LGG viable bacteria in the fermentation base after addition is 5.0×10 6 CFU / g.

[0075] Process:

[0076] 1. Dissolve milk powder in 60℃ water and keep warm for half an hour to obtain reconstituted milk;

[0077] 2. After dry mixing white sugar, gelatin, agar and 31% water, disperse it into 70-75℃ water under high-speed stirring. After uniform dispersion, mix it with the reconstituted milk in step 1. Homogenize it at 30 / 160bar and 60-65℃, then sterilize it at 121℃ / 45s, and cool it to 40℃ for storage.

[0078] 3. Add according to the amount Acidifix TM 1.0 and Make it fully dissolved;

[0079] 4. After filling, ferment at 40-43°C. Fermentation is terminated when the pH reaches below 4.5 and the acidity is above 70°T.

[0080] The yogurt obtained in Example 2 was stored at 25°C for 6 months, and the viable cell count and pH value of the yogurt were tested on the third day (D3), the first month (M1), the second month (M2), the fourth month (M4) and the sixth month (M6) after preparation. The results are shown in Tables 8 and 9. Table 8 shows the viable cell count test results of the yogurt provided in Example 2 of the present invention at 25°C, and Table 9 shows the pH value test results of the yogurt provided in Example 2 of the present invention at 25°C.

[0081] Table 8 Viable bacteria count test results of yogurt provided by Example 2 of the present invention at 25°C

[0082] D0 M1 M2 M4 M6 Example 2 8.2E+06 7.6E+07 5.4E+07 3.1E+07 1.5E+07 Commercially available yogurt 1.5E+10 ＜10 ＜10 ＜10 ＜10

[0083] Table 9 pH test results of yogurt provided by Example 2 of the present invention at 25°C

[0084] D0 M1 M2 M4 M6 Example 2 4.49 4.39 4.31 4.22 4.22 Commercially available yogurt 4.35 3.73 3.65 / /

[0085] Among them, the yogurt available on the market is low-temperature coagulation type yogurt.

[0086] After comparison, the yogurt prepared in Example 2 was compared with the commercially available coagulated yogurt. In terms of the number of lactic acid bacteria, at room temperature (25°C), the number of live bacteria in the example was effectively maintained, while the number of live bacteria in the commercial yogurt decreased sharply, and basically no live bacteria were detected after one month. From the perspective of pH value, the commercial yogurt was severely acidic, with a pH of 3.65, which was severely acidic and unacceptable. The pH value of the yogurt prepared in Example 2 dropped by 0.2 compared with the lower limit, and the reduction was acceptable.

[0087] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A method for preparing room temperature live bacteria fermented milk, comprising the following steps: Inoculating lactose-negative bacteria other than Lactobacillus rhamnosus and Lactobacillus rhamnosus into the fermentation base material and then filling the fermentation base material to obtain room-temperature live bacteria fermented milk after fermentation; The fermentation base material is added with proliferation factors other than lactose; The added amount of the proliferation factor is 0.6wt%~1.2wt%; The lactose-negative bacteria are selected from YoFlex® Acidifix™ 1.0; The Lactobacillus rhamnosus is selected from nu-trish® LGG®; The addition amount of the lactose-negative bacteria is 80-150 U / t; The addition amount of the Lactobacillus rhamnosus is 1.0×10 6 CFU / g or above.

2. The preparation method according to claim 1, characterized in that The growth factor is selected from at least one of glucose, fructose, galactose, arabinose, ribose, mannose, rhamnose, fucose, tagatose, sucrose, maltose, cellobiose, trehalose, melezitose, gentiobiose, acetylglucosamine and white sugar.

3. The preparation method according to claim 1, characterized in that The addition amount of the Lactobacillus rhamnosus is 1.0×10 6 CFU / g ~1.0×10 9 CFU / g.

4. The preparation method according to claim 1, characterized in that The fermentation base further comprises: a milk raw material; and optionally, a flavoring agent, a stabilizer, a protein component and water.

5. The preparation method according to claim 4, characterized in that The fermentation base comprises: 80%~99% milk raw materials; 0~2% protein ingredients; 0-12% flavoring agent; 0~3% stabilizer; The remaining amount of water.

6. The preparation method according to claim 5, characterized in that The milk raw material is selected from at least one of an animal-based milk raw material and a plant-based milk raw material; The protein component is selected from one or more of milk protein, soy protein isolate, soy protein concentrate, pea protein, peanut protein, walnut protein and coconut milk; The flavoring agent is selected from one or more of isomaltulose, maltitol, erythritol, xylitol, galactitol, mannitol, sorbitol and essence; The stabilizer is selected from one or more of pectin, agar, gellan gum, starch, carrageenan, gelatin, diacetyl tartaric acid mono- and diglycerides, mono- and diglycerol fatty acid esters, acetylated distarch phosphate, hydroxypropyl distarch phosphate, citrus fiber and xanthan gum.

7. The preparation method according to claim 6, characterized in that The milk protein is selected from whey protein or casein.

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