CN115380954A

CN115380954A - Yoghourt and preparation method thereof

Info

Publication number: CN115380954A
Application number: CN202211031124.7A
Authority: CN
Inventors: 刘瑞军; 包志强; 边晓旭
Original assignee: New Hope Blue Sea Dairy Beijing Co ltd
Current assignee: New Hope Blue Sea Dairy Beijing Co ltd
Priority date: 2022-08-26
Filing date: 2022-08-26
Publication date: 2022-11-25

Abstract

The application discloses a yoghourt and a preparation method thereof, wherein the yoghourt comprises the following raw materials in percentage by weight: 0-4% of whey powder, 0-4% of milk protein powder, 0.4-1.5% of sucrose, 1-10% of Yidaixin sugar, 0-2.5% of thickening agent, 0-0.3% of emulsifier and 0.002-0.03% of fermentation composition, and the balance of raw milk, wherein the fermentation composition comprises at least one strain, and the strain is a lactose-deficient strain capable of glycolysis sucrose; the lactose-deficient strain does not carry out glycolysis reaction on lactose, the strain only carries out glycolysis on cane sugar in the glycolysis process, the glycolysis reaction on the lactose is avoided, meanwhile, the production amount of lactic acid in the glycolysis is controlled by controlling the content of the cane sugar in the raw materials to be 0.4-1.5%, the acidity range of fermented yoghourt can be controlled, the stability of sour and sweet mouthfeel of the yoghourt in the transportation and sale processes is improved, and the overall quality of the yoghourt is more stable.

Description

Yoghourt and preparation method thereof

Technical Field

The application relates to the technical field of dairy products, in particular to yoghourt and a preparation method thereof.

Background

In recent years, yogurt is highly preferred by consumers for its good taste and physiological function. The yoghourt is a food prepared by fermenting cow milk serving as a main raw material through lactic acid bacteria.

With the popularization of yogurt products and the expansion of sales areas, continuous cold chain transportation, even cold storage and preservation cannot be realized in many places of China, so in recent years, various manufacturers compete for the development of low-temperature yogurt. At present, the low-temperature yoghourt realizes the stability of the product state and the acidity in the shelf life by re-sterilization after fermentation, namely a mode of killing lactic acid bacteria, thereby achieving the aim of normal-temperature storage. Thus, the operation cost of a manufacturer is greatly increased, and the production profit margin is reduced. In addition, the low-temperature yoghurt ensures the stability of the acidity of the product by improving the cold chain condition in the transportation process or properly reducing the shelf life of the product at present. Greatly increasing the operation cost of manufacturers and reducing the profit rate of production.

Due to the characteristic that lactobacillus can continuously ferment and grow in the product at low temperature, the product quality is not controllable, and living bacteria type low-temperature yoghourt with better performance does not appear all the time.

Disclosure of Invention

The embodiment of the application provides yoghourt and a preparation method thereof, and aims to solve the technical problems that the number of viable bacteria is reduced, the nutritive value is reduced and the acidity is uncontrollable along with the increase of the acidity in the prior art.

The embodiment of the first aspect of the application provides a preparation method of yoghourt, and the raw materials of the yoghourt comprise the following components in percentage by weight:

0-4% of whey powder, 0-4% of milk protein powder, 0.4-1.5% of sucrose, 1-10% of itaixin, 0-2.5% of thickening agent, 0-0.3% of emulsifying agent and 0.002-0.03% of fermentation composition, and the balance of raw milk, wherein the fermentation composition comprises at least one strain which is a lactose-deficient strain capable of glycolysis sucrose;

the method comprises the following steps:

1) Mixing raw materials except the fermentation composition;

2) Preheating, homogenizing, sterilizing and cooling the material obtained in the step 1) to obtain a substrate to be fermented;

3) Adding a fermentation composition into the substrate to be fermented in the step 2) for fermentation until the acidity reaches a predetermined acidity, wherein the predetermined acidity is more than 70 degrees T, and preferably 70-80 degrees T;

4) Filling the mixture fermented in the step 3) to obtain the yoghourt.

In the embodiment of the application, in the step 2), the material obtained in the step 1) is subjected to preheating treatment at 55-75 ℃.

In the embodiment of the application, in the step 2), the preheated material is homogenized under the pressure of 180-200 bar and at the temperature of 60-65 ℃.

In the embodiment of the application, in the step 2), the homogenized material is sterilized at the temperature of 85-138 ℃, and the sterilization time is 3-900 seconds.

In the embodiment of the application, in the step 2), the sterilized material is cooled to 35-45 ℃ to obtain the substrate to be fermented.

In the embodiment of the application, in the step 3), the substrate to be fermented is fermented in an anaerobic environment at the temperature of 35-45 ℃.

In the embodiment of the application, the raw milk is one or more of raw milk, raw goat milk, skim milk powder and full-fat milk powder.

In the embodiment of the application, the whey powder contains milk protein with the mass fraction of more than or equal to 25%.

In the examples of the present application, the fermentation composition comprises one or more of lactobacillus bulgaricus, streptococcus thermophilus; and/or the presence of a gas in the gas,

the strain is a strain with inactivated beta-galactosidase.

Embodiments of the second aspect of the present application also provide yogurts prepared by the preparation method of the yoghurt of the first aspect.

The yogurt provided by the embodiment of the application comprises the following raw materials in percentage by weight: 0-4% of whey powder, 0-4% of milk protein powder, 0.4-1.5% of sucrose, 1-10% of Ito Xin sugar, 0-2.5% of thickening agent, 0-0.3% of emulsifying agent and 0.002-0.03% of fermentation composition, and the balance being raw material milk, wherein the fermentation composition comprises at least one strain, the strain is a lactose-deficient strain capable of fermenting sucrose, the strain is selected from lactose-deficient strains, and does not carry out glycolysis reaction on lactose, only the strain ferments the sucrose in the glycolysis process, and does not carry out the glycolysis reaction on the lactose, and meanwhile, the content of the sucrose in the raw material is controlled to be 0.4-1.5%, the production amount of lactic acid in glycolysis is controlled, the acidity range of the fermented yogurt can be controlled, the fermentation acidity of the yogurt is effectively controlled through the design of a formula and the improvement of a production process, the fermentation acidity of the yogurt is designed to be a controllable range value, the shelf life of the yogurt at a low temperature is prolonged to be more than 2 months, the stability of the sour taste of the yogurt in the transportation and the sale process is improved, and the overall quality of the yogurt is more stable.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present application, and it is obvious for a person skilled in the art to obtain other drawings based on the drawings without any creative effort.

FIG. 1 is a schematic representation of whey separation in yoghurts provided by a comparative example of the present application.

Detailed description of the preferred embodiments

Features and exemplary embodiments of various aspects of the present application will be described in detail below, and in order to make the objects, technical solutions and advantages of the present application more apparent, the present application will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application. It will be apparent to one skilled in the art that the present application may be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present application by illustrating examples thereof.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrases "comprising 8230; \8230;" comprises 8230; "does not exclude the presence of additional like elements in a process, method, article, or apparatus that comprises the element.

In order to solve the above problems, embodiments of a yogurt and a preparation method thereof are provided, and embodiments of the yogurt and the preparation method thereof will be described below with reference to the accompanying drawings.

The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention. 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 prior art, the acidity of the low-temperature yoghourt containing live bacteria is continuously increased along with the prolonging of the storage time, so that the taste becomes more and more sour, the low-temperature yoghourt is difficult to accept by consumers, and the shelf life and the sale of the low-temperature yoghourt are influenced. Meanwhile, the increase of the acidity of the yoghourt accelerates the death of active lactic acid bacteria in the yoghourt and reduces the nutritive value of the low-temperature yoghourt.

In order to alleviate the problems, the inventor uses a yoghourt preparation method to prolong the shelf life of the yoghourt and realize accurate acidity control on the basis of keeping the original yoghourt taste and nutritive value.

The low-temperature yoghourt on the market at present has the following problems: the low-temperature yoghourt causes the imbalance of the sour-sweet ratio due to the fact that the increase of the acidity of the yoghourt can not be controlled, and the mouthfeel is changed. Finally, the taste is unpleasant; the death of active lactic acid bacteria contained in the yogurt is accelerated due to the uncontrollable increase of acidity, and the nutritional value of the low-temperature yogurt is lost.

How to balance and consider, the method for preparing the yoghourt with controllable acidity and reliable mouthfeel and nutritional value is the key direction of research of the inventor.

0-4% of whey powder, 0-4% of milk protein powder, 0.4-1.5% of sucrose, 1-10% of Yidaixin sugar, 0-2.5% of thickening agent, 0-0.3% of emulsifier and 0.002-0.03% of fermentation composition, and the balance of raw milk, wherein the fermentation composition comprises at least one strain, and the strain is a lactose-deficient strain capable of glycolysis sucrose.

According to the embodiment of the application, the formula and the production process of the current yoghourt do not consider to effectively control the acidity of the low-temperature yoghourt in the shelf life, and do not well treat the quality hazard caused by postacidification of the yoghourt, so that the problems that the acidity of the low-temperature yoghourt product is increased and the mouthfeel is more and more sour are caused in the transportation or sale process. Meanwhile, the activity of the lactobacillus is weakened when the acidity is increased, so that the nutritive value of the yoghourt is reduced. In the embodiment of the application, the lactose-deficient strain is selected, the glycolysis reaction is not performed on lactose, the strain only ferments sucrose in the glycolysis process, the glycolysis reaction is not performed on lactose, and the production amount of lactic acid in the glycolysis is controlled by controlling the sucrose content in the raw material to be 0.4-1%, so that the acidity range of fermented yogurt can be controlled.

According to the embodiment of the application, the raw materials of the yoghurt can also comprise milk-based sources, thickening agents, sweetening agents, fermenting agents, emulsifying agents and other raw materials, and the yoghurt does not contain sucrose, fruit and vegetable juices and the like which can be nutrient substrates which can be utilized by lactose-deficient strains, such as carbon sources which are converted and hydrolyzed to generate sour substances, and the sour substances can be lactic acid, acetic acid, ethanol, formic acid and the like.

According to the present embodiment, the raw milk may be selected from raw milk, raw goat milk, skim milk powder, whole milk powder, etc. or a combination thereof; the milk protein material may be selected from concentrated milk protein powder, whey powder, etc. or their combination. The lactose content in the conventional cow milk is between 4.5 and 5.5 percent, and the lactose content in the cow milk is too high, so that the lactic acid content of the yoghurt in the shelf life is also too high, the lactose-deficient strain is selected in the embodiment of the application, glycolysis reaction is not carried out on the lactose, lactic acid bacteria only carry out glycolysis on sucrose in the glycolysis process, and the lactic acid bacteria do not carry out glycolysis reaction on the lactose, so that the acidity range value of the fermented milk can be controlled.

The Yidaixin sugar in the embodiment of the application endows the sour milk with sweet taste, and has no influence on the acidity change of the sour milk; the content of the milk protein in the milk protein powder is more than or equal to 10 percent, so that the content of the milk protein can be increased, and the milk protein in the yoghourt can be provided; the thickener can be one or more of pectin, agar, red algae powder, gelatin, and modified starch; the emulsifier is one or more of diacetyl tartaric acid monoglyceride and diglyceride fatty acid ester.

In some embodiments, the method of making the yogurt comprises:

1) Mixing raw materials except the fermentation composition;

3) Adding a fermentation composition into the substrate to be fermented in the step 2) for fermentation until the acidity reaches a predetermined acidity, wherein the predetermined acidity is more than 70 DEG T, and preferably 70-80 DEG T;

4) Filling the mixture fermented in the step 3) to obtain the yoghourt.

According to the embodiment of the application, the acidity of the yoghurt during filling is controlled to be a predetermined acidity, and the predetermined acidity is above 70 DEG T, and is preferably 70-80 DEG T. The acidity of the fermentation end point of the yoghourt can change along with the difference of protein content, the higher the protein value content is, the higher the end point acidity of the product can be, the conventional yoghourt has certain protein content, and the preset acidity of the yoghourt is between 70 and 850T. The content of sucrose in the raw materials of the yoghourt is 0.4-1%, the sucrose is fixed, the lactose-deficient strain can only utilize sucrose, the acidity of the yoghourt is controllable within the shelf life of the yoghourt and is also 70-80 DEG T, and the influence on the use experience of consumers due to too high acidity of the yoghourt within the shelf life is avoided.

According to the embodiment of the application, the fermentation acidity of the yoghourt is effectively controlled through the design of the formula and the improvement of the production process, the fermentation acidity of the yoghourt is designed to be a controllable range value, the shelf life of the low-temperature yoghourt at present is prolonged to be more than 2 months (the conventional shelf life of the common yoghourt), the stability of the sour and sweet mouthfeel of the yoghourt in the transportation and sale processes is improved, and the overall quality of the yoghourt is more stable.

In some embodiments, in the step 2), the material obtained in the step 1) is subjected to preheating treatment at 55-75 ℃.

According to the embodiment of the application, the mixing process in the step 1) can be heated, so that the subsequent preheating and fermentation rates can be improved; if the mixing process in the step 1) is not heated, the preheating process is properly prolonged, and the normal fermentation is ensured.

In some embodiments, in the step 2), the preheated material is homogenized under the pressure of 180-200 bar and the temperature of 60-65 ℃.

In some embodiments, in the step 2), the homogenized material is sterilized at a temperature of 85 to 138 ℃ for 3 to 900 seconds, preferably 5 to 600 seconds.

According to the embodiment of the application, the sterilization treatment is carried out in the temperature range, so that the mixed bacteria in the yoghourt can be killed, and the yoghourt is prevented from being polluted.

In some embodiments, in the step 2), the sterilized materials are cooled to 35-45 ℃ to obtain the substrate to be fermented.

In some embodiments, in step 3), the substrate to be fermented is fermented in an anaerobic environment at 35 to 45 ℃.

In some embodiments, the raw milk is one or more of raw cow milk, raw sheep milk, skim milk powder, and whole milk powder.

In some embodiments, the whey powder comprises milk proteins in a mass fraction of greater than or equal to 25%.

In the embodiment of the application, the whey powder can be whey protein powder, can meet the national standard requirement, and is preferably 60-80%.

In some embodiments, the raw material of the yoghurt further comprises egg yolk powder, and the content of the egg yolk powder is 0-0.5% by weight.

According to the embodiment of the application, the egg yolk powder contains about 30% of protein, about 38% of glyceride, about 19% of phospholipid and a small amount of sugar, minerals, vitamins, pigments, enzymes and the like, and the nutritional ingredients of the yoghourt can be improved by adding the egg yolk powder.

In some embodiments, the fermentation composition comprises one or more of lactobacillus bulgaricus, streptococcus thermophilus.

In some embodiments, the bacterial species is a β -galactosidase-inactivated strain.

According to the embodiments of the present application, the reason for the continuous increase of acidity of yogurt in shelf life is due to the continuous hydrolysis of carbon source in yogurt by intracellular enzymes of the starter, resulting in continuous production of acids. Therefore, the strains in the yoghourt select the strains with lactose deficiency and can only utilize sucrose, the selectivity of the strains is the specific selectivity of the fermentation composition on a carbon source, and other strains with the selectivity different from that of the strains do not exist in the fermentation composition. Due to the difference of enzyme systems in cells, in addition to energy, the strains metabolize the carbon source to finally produce sour substances, so that the milk protein can be denatured, and the mouthfeel of the yoghourt is changed into sour. In the embodiment of the application, the strain can be lactobacillus bulgaricus and streptococcus thermophilus, both of which are lactose-deficient strains, and can be AcIDIFIX1.0 strain of Hansen of Danmark, sucrose is glycolyzed by fermentation to produce glucose and fructose, and the glucose is further glycolyzed to produce lactic acid. The beta-galactosidase activity in the cell walls of Lactobacillus bulgaricus and Streptococcus thermophilus has been inactivated and only sucrose can be used.

The embodiment of the second aspect of the application also provides the yoghourt prepared by the preparation method of the yoghourt of the first aspect.

According to the embodiment of the application, the acidity of the fermented milk can be formulated according to the taste requirement, the acidity of the yogurt can be controlled to be less than 10 DEG T within a longer shelf life, and the shelf life can be 2-4 months; the fluctuation range of the titration acidity is more than 50 degrees T within the shelf life of the common yoghourt, and the shelf life is less than 25 days.

Examples

The present disclosure is more particularly described in the following examples that are intended as illustrative only, since various modifications and changes within the scope of the present disclosure will be apparent to those skilled in the art. Unless otherwise indicated, all parts, percentages, and ratios reported in the following examples are on a weight basis, and all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further treatment, and the equipment used in the examples is commercially available.

In the following examples, the sources of the raw materials used were:

raw milk, whole/skim milk powder, cream: dairy products second plant, guangming Dairy products GmbH.

Milk protein powder: davilin International trade, inc. The milk protein powder comprises whole milk protein powder with 60% of milk protein content or whey powder with 80% of milk protein content.

Strain Acidifix TM: khansen (Beijing) trade company, inc.

High fructose syrup, jam: gambling agriculture science and technology limited.

Example 1

The embodiment of the application provides a preparation method of yoghourt, which comprises the following formula:

the process comprises the following steps:

1. heating or not heating raw milk, adding sucrose, bovine protein powder and Yidaixin sugar, and continuously stirring for 30 minutes after all the raw materials are added.

2. Heating the material obtained in the step 1 to 55 ℃, homogenizing under 200bar pressure, and sterilizing at 138 ℃ for 3 seconds to obtain the fermentation substrate.

3. Cooling the fermentation substrate obtained in the step 2 to 35 ℃, adding a leavening agent lactobacillus bulgaricus: streptococcus thermophilus (1.

4. And (4) filling the yoghourt obtained in the step (3) under an aseptic condition, and storing at a low temperature.

5. The protein content in the raw material is 3.92%, and the titration acidity is 79 DEG T.

Example 2

The embodiment of the application provides a preparation method of yoghourt, which comprises the following steps:

the process comprises the following steps:

1. heating or not heating raw milk, adding sucrose, modified starch, red algae powder, and Yidaixin sugar, and stirring for 30 min.

2. And (3) heating the material obtained in the step (1) to 75 ℃, homogenizing under the pressure of 200bar, and sterilizing at 85 ℃ for 900 seconds to obtain the fermentation substrate.

3. Cooling the fermentation substrate obtained in the step 2 to 45 ℃, adding a leavening agent of lactobacillus bulgaricus: streptococcus thermophilus (1.

4. And (4) filling the yoghourt obtained in the step (3) under the aseptic condition, and storing at low temperature.

The protein content in the raw material was 3.32%, and the titration acidity was 71 ° T.

Example 3

the process comprises the following steps:

2. Heating the material obtained in the step 1 to 65 ℃, homogenizing under 200bar pressure, and sterilizing at 95 ℃ for 300 seconds to obtain the fermentation substrate.

3. Cooling the fermentation substrate obtained in the step 2 to 42 ℃, adding a leavening agent lactobacillus bulgaricus: streptococcus thermophilus (1.

The protein content in the raw material was 3.21%, and the titration acidity was 74 ° T.

Example 4

the process comprises the following steps:

1. heating or not heating raw milk, adding sucrose, modified starch, red algae powder, and Yidaixin sugar, and stirring for 30 min after all the raw materials are added.

The protein content in the raw material was 3.29%, and the titration acidity was 73 ° T.

Example 5

the process comprises the following steps:

2. Heating the material obtained in the step 1 to 60 ℃, homogenizing under 200bar pressure, and sterilizing at 95 ℃ for 300 seconds to obtain the fermentation substrate.

3. Cooling the fermentation substrate obtained in the step 2 to 39 ℃, adding a leavening agent of lactobacillus bulgaricus: streptococcus thermophilus (1.

The protein content in the raw material was 3.54%, and the titration acidity was 72 ° T.

Example 6

the process comprises the following steps:

2. Heating the material obtained in the step 1 to 64 ℃, homogenizing under the pressure of 200bar, and sterilizing at 95 ℃ for 300 seconds to obtain the fermentation substrate.

3. Cooling the fermentation substrate obtained in the step 2 to 40 ℃, adding a leavening agent lactobacillus bulgaricus: streptococcus thermophilus (1.

The protein content in the raw material was 3.24%, and the titration acidity was 78 ° T.

Example 7

the process comprises the following steps:

2. And (3) heating the material obtained in the step (1) to 65 ℃, homogenizing under the pressure of 200bar, and sterilizing at 95 ℃ for 300 seconds to obtain the fermentation substrate.

3. Cooling the fermentation substrate obtained in the step 2 to 42 ℃, adding a leavening agent of lactobacillus bulgaricus: streptococcus thermophilus (1.

The protein content in the raw material was 3.22%, and the titration acidity was 70 ° T.

Example 8

the process comprises the following steps:

3. Cooling the fermentation substrate obtained in the step 2 to 41 ℃, adding a leavening agent of lactobacillus bulgaricus: streptococcus thermophilus (1.

The protein content in the raw material is 3.84%, and the titration acidity is 73 ℃ T.

Comparative example 1

The process comprises the following steps:

1. heating raw milk to 45 deg.C, adding whey powder, stirring for 30 min, adding sucrose, gelatin, pectin, and acetylated distarch phosphate, and stirring for 15 min.

The protein content in the raw material was 3.4%, and the titration acidity was 73 ° T.

Comparative example 2-Low protein content

The process comprises the following steps:

1. heating raw milk to 45 deg.C, adding high fructose syrup, sucrose and pectin, and stirring for 15 min.

The protein content in the raw material is 3.0%, and the titration acidity is 75 DEG T.

Comparative example 3-sucrose is added in the common yogurt

The process comprises the following steps:

1. the raw milk was heated to 45 ℃, sucrose was added, and stirring was continued for 15 minutes.

The protein content in the raw material was 3.2%, and the titrating acidity was 73 ° T.

Comparative example 4 too high protein content

The process comprises the following steps:

1. heating raw milk to 65 deg.C, homogenizing under 200bar pressure, and sterilizing at 95 deg.C for 300 s to obtain fermentation substrate.

2. Cooling the fermentation substrate obtained in the step 1 to 42 ℃, adding lactase and a leavening agent lactobacillus bulgaricus: streptococcus thermophilus (1.

3. And (3) filling the yoghourt obtained in the step (2) under an aseptic condition, and storing at a low temperature.

The protein content in the raw material was 3.9%, and the titration acidity was 85 ° T.

Problems with the comparative product described above: 1. when the fermentation is finished when the titrated acidity reaches 80T due to the excessively high protein, the pH of the product does not reach the predetermined acidity, and thus the feeling of acidity is insufficient. 2. The protein is too high, the fermentation speed is high, the strain produces acid quickly, and meanwhile, the flavor substances are generated too little, so that the product flavor is insufficient. 3. The protein is too high, the protein stability is poor, and the protein is not suitable for long-time storage at normal temperature.

Effect example 1

Sensory evaluation is carried out on the products of the examples after being stored for 30 days at normal temperature, and the results show that the products of the examples are basically consistent in state, taste and flavor at the beginning and the end of the quality guarantee period. Then, the related indexes are detected, and the results are shown in the following table 1.

Table 1 examples and comparative examples yogurt organoleptic ratings.

Wherein, the acidity is high: the product acidity reaches over 100 degrees T, and the acid feeling in the oral cavity is serious and obvious uncomfortable feeling is caused. Heavy sour feeling: the product has low acidity value, but unbalanced sweet-sour ratio and obvious sour feeling.

The mouthfeel is fresh and astringent: the tongue has a gritty feel, which causes unpleasant taste.

The flavor is normal: the normal yoghurt has a cheese taste and a fermented taste, and no other foreign taste.

As can be seen from the table, the product of the embodiment of the invention is placed at normal temperature within the quality guarantee period, the acidity and the state of the product are not influenced, the viable count is stable, and the taste and the flavor are stable. The comparative product has the defects of layering, serious whey precipitation, over-acid taste and serious attenuation of the number of lactic acid bacteria, and does not conform to the standard of fermented milk any more. The whey separation effect of comparative example 2 is shown in fig. 1, where the layer distinguished from other colors in the middle part is separated whey.

Effect example 2

After the products of the above examples and comparative examples are filled and subpackaged, the low temperature (2-6 ℃) is kept for 90 days for carrying out the step tracking test of the titration acidity value, and the result shows that the titration acidity of the products in the time period is effectively controlled within 100 DEG T, and the texture state, the flavor and the sweet-sour ratio of the products are basically consistent within 90 days. The results are given in table 2 below:

the data in the tables 1 and 2 show that the low-temperature yogurt product has a longer shelf life, the shelf life of the low-temperature yogurt is prolonged to 2-3 times, the acidity value of the product in the shelf life is effectively controlled within 100 DEG T, the texture, the flavor and the sour and sweet taste of the low-temperature yogurt product in the acidity value range are basically consistent through tracking test, and people have higher pleasure after tasting the low-temperature yogurt product in a plurality of people.

In accordance with the foregoing embodiments of the present application, these embodiments are not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the application and its practical application, to thereby enable others skilled in the art to best utilize the application and its various modifications as are suited to the particular use contemplated. The application is limited only by the claims and their full scope and equivalents.

Claims

1. The preparation method of the yoghourt is characterized in that the yoghourt comprises the following raw materials in percentage by weight:

0-4% of whey powder, 0-4% of milk protein powder, 0.4-1.5% of sucrose, 1-10% of Yidaixin sugar, 0-2.5% of thickening agent, 0-0.3% of emulsifier and 0.002-0.03% of fermentation composition, and the balance of raw milk, wherein the fermentation composition comprises at least one strain, and the strain is a lactose-deficient strain capable of glycolysis sucrose;

the method comprises the following steps:

1) Mixing raw materials except the fermentation composition;

4) Filling the mixture fermented in the step 3) to obtain the yoghourt.

2. The method of claim 1, wherein in step 2), the material obtained in step 1) is pre-heated at 55 to 75 ℃.

3. The method according to claim 1, wherein in the step 2), the preheated material is homogenized at a pressure of 180 to 200bar and a temperature of 60 to 65 ℃.

4. The preparation method of claim 1, wherein in the step 2), the homogenized material is sterilized at a temperature of 85-138 ℃ for 3-900 seconds.

5. The method according to claim 1, wherein in the step 2), the sterilized material is cooled to 35 to 45 ℃ to obtain the substrate to be fermented.

6. The method according to claim 1, wherein the substrate to be fermented in the step 3) is fermented in an anaerobic environment at 35 to 45 ℃.

7. The method of claim 1, wherein the raw milk is one or more of raw milk, raw goat milk, skim milk powder, and whole milk powder.

8. The method according to claim 1, wherein the whey powder contains milk proteins in an amount of 25% or more by mass.

9. The method of claim 1, wherein the fermentation composition comprises one or more of lactobacillus bulgaricus, streptococcus thermophilus; and/or the presence of a gas in the gas,

the strain is a strain with inactivated beta-galactosidase.

10. Viable bacteria type low temperature yoghurt prepared by the method for preparing the viable bacteria type low temperature yoghurt of any one of claims 1 to 9.