Preparation method of double-protein yoghurt

Abstract

The preparation method of the double-protein yoghourt comprises the following steps: fermenting mixed emulsion by adopting zymophyte; the main components of the mixed emulsion are plant-based milk and animal milk; the zymophyte comprises Weissella fusiformis and yoghurt zymophyte. The obtained double-protein yoghurt contains animal-derived and plant-derived proteins at the same time, animal and plant protein complementation is achieved, dietary fibers lacked in the animal-derived yoghurt are provided, and more comprehensive nutrition is provided for the human body. The obtained double-protein yoghurt can still show stable texture without adding a stabilizer, has no layering phenomenon, is good in coagulability, does not separate out whey in a storage period, and is a healthy food which is free of additives and rich in nutrition; the obtained double-protein yogurt is free of bad flavors such as fishy smell, high in sensory score and good in commercial prospect.

Description

Technical Field

[0001] The invention relates to a method for preparing yogurt, in particular to a method for preparing double-protein yogurt. Background Art

[0002] Plant-based dairy products are rich in protein, complex carbohydrates, vitamins and fiber, and have become increasingly popular in recent years. When consumed with traditional animal dairy products, they complement plant and animal proteins, while providing dietary fiber that is lacking in yogurt, providing the human body with more comprehensive nutrition. It is precisely because plant-based dairy products differ greatly from traditional animal milk that it is difficult to further develop plant-based and animal-based composite dairy products.

[0003] Traditional yogurt fermentation bacteria have poor adaptability to plant-based dairy products, and the resulting fermented products have problems such as poor stability, easy whey precipitation, and bad taste, and cannot obtain satisfactory products. Without the use of additional stabilizers, currently only a small amount of plant-based dairy products can be added to animal-based dairy products to reduce the impact on product stability, which does not bring much nutritional value improvement; in addition, additional seasoning is often required to cover up the fishy smell, which is costly and cannot be considered by consumers as a healthy and nutritious food. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a method for preparing double-protein yogurt without using a stabilizer.

[0005] The technical solution adopted by the present invention to solve its technical problem is as follows: a method for making double-protein yogurt, fermenting a mixed emulsion with fermentation bacteria; the main components of the mixed emulsion are plant-based milk and animal milk; the fermentation bacteria include Weissella fusion.

[0006] Preferably, the number of live bacteria inoculated per liter of mixed emulsion is equivalent to that of 5-60 mL of bacteria with a concentration of 10 6 -10 10 cfu / mL of fermentation broth.

[0007] Preferably, the fermentation bacteria include Weissella fusionii SY628.

[0008] Preferably, the fermentation bacteria include fusion Weissella SY628 and yogurt fermentation bacteria.

[0009] Preferably, the relationship between the inoculation amount of Weissella SY628 and the mixed emulsion is: the number of viable bacteria of Weissella SY628 inoculated per liter of mixed emulsion is equivalent to the number of live bacteria inoculated with 5-60 mL of bacteria with a concentration of 10 6 -10 10cfu / mL of fermentation broth.

[0010] Preferably, the relationship between the inoculation amount of yogurt fermentation bacteria and the amount of animal milk in the mixed emulsion is: the number of live bacteria of yogurt fermentation bacteria inoculated with one liter of animal milk is equivalent to the number of live bacteria inoculated with 5-60 mL of bacterial cell concentration of 10 6 -10 10 cfu / mL of fermentation broth.

[0011] Preferably, the fermentation temperature is 28-45°C.

[0012] Preferably, the fermentation time is 6 to 12 hours.

[0013] Preferably, the concentration of the plant-based milk is 6-9° Bx.

[0014] Preferably, the particle size of the solid particles in the plant-based milk is less than 60 mesh.

[0015] Preferably, the particle size of the solid particles in the plant-based milk is less than 200 mesh.

[0016] Preferably, the plant-based milk is seed-based plant-based milk, more preferably one or more of nut-based plant-based milk, cereal-based plant-based milk, and bean-based plant-based milk.

[0017] Preferably, after fermentation, post-ripening is performed: keeping warm at 2-5°C for 12-48 hours.

[0018] Preferably, an edible carbon source is also added to promote fermentation.

[0019] Preferably, the edible carbon source is one or more of sucrose, glucose, fructose, galactose, lactose, oligosaccharides and polysaccharides.

[0020] Preferably, the edible carbon source is sucrose and / or lactose.

[0021] Preferably, the weight of the edible carbon source used is 6% to 12% of the sum of the weight of the plant-based milk and the animal milk.

[0022] Preferably, the weight ratio of plant-based milk to animal milk is 1:9 to 9:1.

[0023] Preferably, the mixed emulsion is further subjected to a pressure homogenization treatment.

[0024] The present invention has the following beneficial effects:

[0025] (1) The present invention uses a double-protein mixed milk composed of plant-based milk and animal milk as a fermentation matrix. The obtained double-protein yogurt contains both animal-based and plant-based proteins, achieving the complementarity of animal and plant proteins, and at the same time provides dietary fiber that is lacking in animal-based yogurt, providing more comprehensive nutrition for the human body;

[0026] (2) The obtained double protein yogurt can still show a stable texture without adding a stabilizer, has no stratification phenomenon, has good coagulation properties, and has no whey precipitation during the storage period. It is a healthy food without additives and rich in nutrition;

[0027] (3) Since no expensive additives such as stabilizers are required, the product has obvious cost advantages;

[0028] (4) The obtained double protein yogurt has no unpleasant flavors such as fishy smell, has a high sensory score, and has a good commercial prospect.

[0029] In addition to the above-described purposes, features and advantages, the present invention has other purposes, features and advantages. The present invention will be further described in detail below with reference to the accompanying drawings.

[0030] Description of microbial preservation:

[0031] The Weissella confusa SY628 involved in the present invention was deposited in the General Microbiology Center of China Microorganism Culture Collection Committee (referred to as CGMCC, address: Institute of Microbiology, Chinese Academy of Sciences, No. 1 Beichen West Road, Chaoyang District, Beijing, China) on September 19, 2024, and the culture deposit number is CGMCC No.32006. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0033] Figure 1 is a photo of the double-protein yogurt product obtained in Example 1 of the present invention;

[0034] Figure 2 is a graph showing changes in the number of viable bacteria of the products obtained in Examples 1 to 3 of the present invention during storage;

[0035] Figure 3 This is a diagram showing the water holding rate of the products obtained in Examples 1 to 3 of the present invention;

[0036] Figure 4 is a graph showing the change in titratable acidity (°T) of the products obtained in Examples 1 to 3 of the present invention during storage;

[0037] Figure 5 is a diagram showing sensory evaluation results of the products obtained in Examples 1 to 3 of the present invention;

[0038] Figure 6is a graph showing the test results of hardness, elasticity and toughness of the products obtained in Examples 1 to 3 of the present invention;

[0039] Figure 7 These are the observation pictures of the morphological characteristics of fused Weissella SY628: left picture, cell morphology of fused Weissella SY628; middle picture, colony morphology of fused Weissella SY628 on MRS solid culture; right picture, colony morphology and colony stringing of fused Weissella SY628 on mMRS solid culture medium. DETAILED DESCRIPTION

[0040] In order to make the purpose, scheme and beneficial technology of the present invention clearer, the present invention is further described in detail below in conjunction with the embodiments and drawings. It should be pointed out that the embodiments described in this specification are only for explaining the present invention, not for limiting the present invention.

[0041] For simplicity, only some numerical ranges are explicitly disclosed herein. However, any lower limit can be combined with any upper limit to form an unambiguous range; and any lower limit can be combined with other lower limits to form an unambiguous range, and any upper limit can be combined with any other upper limit to form an unambiguous range. In addition, although not explicitly stated, each point or single value between the range endpoints is included in the range. Thus, each point or single value can be combined with any other point or single value as its own lower limit or upper limit or with other lower limits or upper limits to form an unambiguous range.

[0042] In the description of this article, it should be noted that, unless otherwise specified, “above” and “below” are inclusive of the number, and the “multiple” in “one or more” means two or more, and the “multiple” in “one or more” means two or more.

[0043] The embodiment of the present invention provides a method for making double-protein yogurt, wherein a mixed emulsion is fermented by fermentation bacteria; the main components of the mixed emulsion are plant-based milk and animal milk; and the fermentation bacteria include Weissella fusion.

[0044] The method for making double-protein yogurt provided by the embodiment of the present invention has the following advantages:

[0045] (1) The double-protein mixed milk composed of plant-based milk and animal milk is used as the fermentation matrix, and the obtained double-protein yogurt contains both animal-based and plant-based proteins, achieving the complementarity of animal and plant proteins, and at the same time provides dietary fiber that is lacking in animal-based yogurt, providing more comprehensive nutrition for the human body;

[0046] (2) The obtained double protein yogurt can still show a stable texture without adding a stabilizer, has no stratification phenomenon, has good coagulation properties, and has no whey precipitation during the storage period. It is a healthy food without additives and rich in nutrition;

[0047] (3) Since no expensive additives such as stabilizers are required, the product has obvious cost advantages;

[0048] (4) The obtained double protein yogurt has no fishy smell, a high sensory score, and has a good commercial prospect.

[0049] In the embodiment of the present invention, the number of live bacteria of fermentation bacteria inoculated per liter of mixed emulsion is equivalent to inoculating 5-60mL of bacteria with a concentration of 10 6 -10 10 cfu / mL of fermentation broth.

[0050] In an embodiment of the present invention, the fermentation bacteria includes Weissella SY628. When the fermentation bacteria includes Weissella SY628, since Weissella SY628 can ferment food containing dietary fiber, it can be used alone for fermentation of mixed emulsion.

[0051] In an embodiment of the present invention, the fermentation bacteria include fusion Weissella SY628 and yogurt fermentation bacteria.

[0052] Commercialized yogurt fermentation bacteria can be purchased directly.

[0053] In the embodiment of the present invention, the relationship between the inoculation amount of Weissella SY628 and the mixed emulsion is: the number of viable bacteria of Weissella SY628 inoculated per liter of mixed emulsion is equivalent to the number of live bacteria inoculated with 5-60 mL of the mixed emulsion with a cell concentration of 10 6 -10 10 cfu / mL of fermentation broth.

[0054] In the embodiment of the present invention, the relationship between the inoculation amount of yogurt fermentation bacteria and the amount of animal milk in the mixed emulsion is: the number of live bacteria of yogurt fermentation bacteria inoculated with one liter of animal milk is equivalent to the number of live bacteria inoculated with 5-60 mL of bacterial cell concentration of 10 6 -10 10 cfu / mL of fermentation broth.

[0055] Before inoculating the fermentation bacteria, the temperature of the plant-based milk should be controlled within a range suitable for the survival of the fermentation bacteria to avoid the death of a large number of fermentation bacteria.

[0056] Sterilization and / or sterilization can be performed according to actual needs, such as before inoculating the fermentation bacteria, after the production is completed, etc. Sterilization can be performed by pasteurization, and sterilization can be performed by high-temperature instantaneous sterilization.

[0057] In an embodiment of the present invention, the fermentation temperature is 28-45°C.

[0058] In an embodiment of the present invention, the fermentation time is 6 to 12 hours.

[0059] In an embodiment of the present invention, the concentration of the plant-based milk is 6-9° Bx.

[0060] In some embodiments of the present invention, the particle size of the solid particles in the plant-based milk is less than 60 mesh. When the maximum particle size of the solid particles in the plant-based milk is at the level of 60 mesh, it contains more residues and has a poor taste. The corresponding products are rare on the market, and conventional commercially available plant-based milks meet the requirement that the solid particle size is less than 60 mesh. When the fermentation bacteria include Weissella fusion SY628, it is also feasible for the maximum particle size of the solid particles in the plant-based milk to be at the level of 60 mesh; because the bacteria have the ability to decompose dietary fiber (such as decomposing insoluble fibers into soluble fibers), the particle size of the solid particles in the plant-based milk can be larger, and a product with a fine texture can be obtained even if it contains a certain amount of residue. Moreover, the product is rich in fiber and has better nutritional value.

[0061] In some embodiments of the present invention, the particle size of the solid particles in the plant-based milk is less than 200 meshes. Under this condition, the product obtained has a fine texture.

[0062] Plant-based milk can be purchased or made at home. If purchased, simply choose the product that meets your requirements. If made at home, the concentration of plant-based milk can be adjusted by controlling the amount of water added, and the particle size of the solid particles in plant-based milk can be controlled by screening.

[0063] Plant-based milk is a beverage made from plants. Since it is a plant product, it is rich in dietary fiber, and traditional yogurt fermentation bacteria have poor adaptability to it.

[0064] In some embodiments of the present invention, the plant-based milk is seed-based milk.

[0065] In some embodiments of the present invention, the plant-based milk is one or more of nut-based plant-based milk, cereal-based plant-based milk, and bean-based plant-based milk.

[0066] Leguminous plants are one of the raw materials for plant milk production. They are highly praised for being rich in protein, complex carbohydrates, vitamins and fiber, making beans an ideal substitute for dairy products. However, there is currently no suitable fermentation agent for fermenting sour soy milk on the market. Public literature shows that sour soy milk fermentation often uses commercial fermentation agents used in fermenting yogurt. The fermented products have problems such as poor stability, easy whey precipitation and bad taste, and cannot obtain satisfactory products.

[0067] In some embodiments of the present invention, the plant-based milk is cooked soy milk.

[0068] The preparation of the cooked soy milk can adopt a conventional method, which generally includes soaking beans, grinding, and boiling the slurry, during which the dregs are filtered out to obtain the cooked soy milk.

[0069] In some embodiments of the present invention, the method for making cooked soy milk comprises: soaking the raw materials and then grinding them to obtain bean paste, removing the dregs from the bean paste to obtain raw soy milk, and boiling the paste to obtain cooked soy milk.

[0070] In some embodiments of the present invention, the raw material soaking time is more than 8 hours.

[0071] In some embodiments of the present invention, the pulping is performed by micro-pressure pulping at 102-105° C. for 5-15 minutes.

[0072] In some embodiments of the present invention, the bean raw material in the cooked soy milk is one or more of soybeans, mung beans, red beans, kidney beans, peas, black beans, green beans, broad beans, lentils, and chickpeas.

[0073] In some embodiments of the present invention, the bean raw material in the cooked soy milk is soybeans.

[0074] In some embodiments of the present invention, the raw soy milk and / or cooked soy milk is further subjected to a pressure homogenization process.

[0075] In some embodiments of the present invention, the pressure homogenization treatment of raw soy milk and / or cooked soy milk is performed at a temperature of 20 MPa to 50 MPa.

[0076] In the embodiment of the present invention, after fermentation, post-ripening is further performed: keeping warm at 2-5° C. for 12-48 hours.

[0077] In an embodiment of the present invention, an edible carbon source is also added to promote fermentation. It can be added before fermentation and / or during fermentation according to actual conditions.

[0078] In an embodiment of the present invention, the edible carbon source is one or more of sucrose, glucose, fructose, galactose, lactose, oligosaccharides and polysaccharides.

[0079] In an embodiment of the present invention, the edible carbon source is sucrose and / or lactose.

[0080] In an embodiment of the present invention, the weight of the edible carbon source used is 6% to 12% of the sum of the weight of the plant-based milk and the animal milk.

[0081] In the embodiment of the present invention, the weight ratio of plant-based milk to animal milk is 1:9 to 9:1. Since the present invention has a good fermentation effect on both plant-based dairy products and animal-based dairy products, the ratio of plant-based milk to animal milk is feasible in a large range; especially when the amount of plant-based milk is large, a product with good stability and good sensory evaluation can be obtained.

[0082] In an embodiment of the present invention, the mixed emulsion is further subjected to a pressurized homogenization treatment. Homogenization can further refine the protein and fat in the emulsion, make the emulsion more uniform, and prevent particle precipitation. In particular, it has a good anti-precipitation effect for a mixed emulsion that has poor uniformity and contains plant ingredients and animal ingredients.

[0083] In some embodiments of the present invention, the mixed emulsion is subjected to pressurized homogenization treatment at a pressure of 20 MPa to 50 MPa.

[0084] In the existing schemes for making plant-based yogurt, it is generally necessary to add stabilizers. This is because the plant-based yogurt protein-polysaccharide gel network structure formed after fermentation is unstable, and whey is easy to precipitate. It is necessary to add stabilizers to enhance water retention capacity and texture stability. The addition of stabilizers makes the production cost higher, the flavor is affected, and it is not recognized by consumers, and the product is difficult to promote. In the present invention, the newly screened high-yield extracellular polysaccharide fusion Weissella is used for fermentation. While efficiently producing lactic acid, it can make good use of the cellulose in the plant-based milk to produce a large amount of extracellular polysaccharides (EPS). EPS can form hydrogen bonds with water molecules, restrict the flow of water, thereby reducing whey precipitation and improving the stability of the gel. This water retention mechanism can not only enhance the texture of plant-based yogurt, but also reduce the demand for exogenous thickeners or stabilizers.

[0085] The inventors also noticed that although lactic acid bacteria generally have the ability to produce exopolysaccharides, they cannot achieve the fermentation effect of the present invention using fused Weissella; it is speculated that on the one hand, it may be due to the higher level of exopolysaccharide production of fused Weissella SY628, and in addition, it is also due to the modification of plant protein by fermentation bacteria, which causes gelation of plant protein during fermentation, so that the produced exopolysaccharides are cross-linked with plant protein to form a more stable network structure, which makes the water retention and texture stability of the fermented product qualitatively improved. In addition, the fermented product has a light smell and does not have the problem of fishy smell of fermented products of general commercial fermentation bacteria, making fused Weissella SY628 very suitable as a fermentation bacteria for plant-based milk.

[0086] In the present invention, a mixed emulsion whose main components are plant-based milk and animal milk is fermented, and the fermentation bacteria fused with Weissella SY628 can use the components of plant-based milk to produce viscous polysaccharides and lactic acid, thereby promoting the coagulation of double-protein yogurt, and the commercial yogurt fermentation bacteria mainly act on animal milk to promote its fermentation and acid production to form a coagulated state; and there is no mutual inhibition between the fused Weissella SY628 and the commercial yogurt fermentation bacteria, so that the product has a good fermentation effect under different raw material ratios, and the double-protein yogurt can be prepared without adding a stabilizer.

[0087] Example

[0088] The following examples describe the disclosure of the present invention in more detail, and these examples are intended for illustrative purposes only, as it will be apparent to those skilled in the art that various modifications and variations will be made within the scope of the disclosure of the present invention. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are by weight. Unless otherwise stated, all reagents used in the examples are available through conventional commercial sources or are synthesized according to conventional methods and can be used directly without further processing. Unless otherwise stated, the instruments used in the examples are available through conventional commercial sources.

[0089] The commercial bacteria used in each embodiment and comparative example are a mixed fermentation bacteria of Lactobacillus delbrueckii subspecies bulgaricus and Streptococcus thermophilus in a ratio of 1:1.

[0090] Example 1

[0091] The preparation method of the double-protein yogurt of the present embodiment comprises the following steps:

[0092] Soaking beans: Weigh 5kg of soybeans and soak them in cold water at a soybean-water ratio of 1:4 for 8 hours;

[0093] Grinding: Grind the beans in a high-concentration fine grinder at a bean-water ratio of 1:1 (w / w, based on dry beans);

[0094] Soybean milk cooking: using an integrated soybean milk cooking machine to cook the soybean milk to obtain cooked soy milk;

[0095] Filtration: The cooked soy milk is initially filtered using a centrifuge with a 200-mesh screen; drinking water is added to dilute the cooked soy milk to a concentration of 7°Bx;

[0096] Preparation: Mix cooked soy milk and milk, with the weight ratio of soy milk to pure milk being 3:7; add sucrose, with the added amount being 9wt% of the sum of the weight of soy milk and pure milk;

[0097] Pasteurization: The slurry obtained above was sterilized at 85°C for 20 min;

[0098] Inoculation: After sterilization, commercial bacteria were mixed with Weissella confusa SY628 (1:1) to make a bacterial concentration of 10 8 cfu / mL of fermented bacterial liquid, inoculate 20mL per liter of soy milk;

[0099] Fermentation: The inoculated slurry was placed at 37°C for 8 hours;

[0100] Post-ripening and refrigeration: The fermented double-protein yogurt is post-ripened at 4° C. for 12 hours to obtain the double-protein fermented yogurt.

[0101] Figure 1 This is a photo of the double-protein yogurt obtained in this example. It can be seen that the obtained product is a solidified state that can be scooped up in blocks; the product is milky white in color, has a smooth and flat surface, a fine texture, smells fruity, has no bean smell, and no obvious water analysis.

[0102] The protein content of double-protein yogurt was tested in accordance with GB5009.5-2016, and the protein content was 3.20±0.12g / 100g.

[0103] Example 2

[0104] The preparation method of the double-protein yogurt of the present embodiment comprises the following steps:

[0105] Soaking beans: Weigh 5kg of soybeans and soak them in cold water at a soybean-water ratio of 1:4 for 8 hours;

[0106] Grinding: Grind the beans in a high-concentration fine grinder at a bean-water ratio of 1:1 (w / w, based on dry beans);

[0107] Soybean milk cooking: using an integrated soybean milk cooking machine to cook the soybean milk to obtain cooked soy milk;

[0108] Filtration: The cooked soy milk is initially filtered using a centrifuge with a 200-mesh screen; drinking water is added to dilute the cooked soy milk to a concentration of 7°Bx;

[0109] Preparation: Mix cooked soy milk and milk, with the weight ratio of soy milk to pure milk being 5:5; add sucrose, the added amount being 9wt% of the sum of the weight of soy milk and pure milk;

[0110] Pasteurization: The slurry obtained above was sterilized at 85°C for 20 min;

[0111] Inoculation: After sterilization, commercial bacteria were mixed with Weissella confusa SY628 (1:1) to make a bacterial concentration of 10 8 cfu / mL of fermented bacterial liquid, inoculate 20mL per liter of soy milk;

[0112] Fermentation: The inoculated slurry was placed at 37°C for 8 hours;

[0113] Post-ripening and refrigeration: The fermented double-protein yogurt is post-ripened at 4° C. for 12 hours to obtain the double-protein fermented yogurt.

[0114] The obtained double-protein yogurt product is a solidified state that can be scooped up in blocks, has a milky white color, a smooth and flat surface, a fine texture, smells fruity, has no bean smell, and has no obvious water analysis.

[0115] The protein content of double-protein yogurt was tested in accordance with GB5009.5-2016, and the protein content was 3.3±0.15g / 100g.

[0116] Example 3

[0117] The preparation method of the double-protein yogurt of the present embodiment comprises the following steps:

[0118] Soaking beans: Weigh 5kg of soybeans and soak them in cold water at a soybean-water ratio of 1:4 for 8 hours;

[0119] Grinding: Grind the beans in a high-concentration fine grinder at a bean-water ratio of 1:1 (w / w, based on dry beans);

[0120] Soybean milk cooking: using an integrated soybean milk cooking machine to cook the soybean milk to obtain cooked soy milk;

[0121] Filtration: The cooked soy milk is initially filtered using a centrifuge with a 200-mesh screen; drinking water is added to dilute the cooked soy milk to a concentration of 7°Bx;

[0122] Preparation: Mix cooked soy milk and milk, with the weight ratio of soy milk to pure milk being 7:3; add sucrose, with the added amount being 9wt% of the sum of the weight of soy milk and pure milk;

[0123] Pasteurization: The slurry obtained above was sterilized at 85°C for 20 min;

[0124] Inoculation: After sterilization, commercial bacteria were mixed with Weissella confusa SY628 (1:1) to make a bacterial concentration of 10 8 cfu / mL of fermented bacterial liquid, inoculate 20mL per liter of soy milk;

[0125] Fermentation: The inoculated slurry was placed at 37°C for 8 hours;

[0126] Post-ripening and refrigeration: The fermented double-protein yogurt is post-ripened at 4° C. for 12 hours to obtain the double-protein fermented yogurt.

[0127] The obtained double-protein yogurt product is a solidified state that can be scooped up in blocks, has a milky white color, a smooth and flat surface, a fine texture, smells fruity, has no bean smell, and has no obvious water analysis.

[0128] The protein content of double-protein yogurt was tested in accordance with GB5009.5-2016, and the protein content was 3.50±0.11g / 100g.

[0129] Detection and analysis

[0130] The products obtained in Examples 1 to 3 were further analyzed for physical and chemical indicators.

[0131] 1) Changes in viable bacterial count

[0132] The prepared product was stored at 4°C and the changes in the number of viable bacteria were tested. Figure 2 As shown in the figure, the number of live lactic acid bacteria in the double-protein yogurt decreases with the storage time. The number of live lactic acid bacteria on the first day of Example 1 is 18.1*10 7 CFU / mL, the number of viable bacteria on the 28th day was 3.2*10 7 CFU / mL. The number of viable bacteria on the first day of Example 2 was 21.1*10 7 CFU / mL, the number of viable bacteria on the 28th day was 3.75*10 7 CFU / mL. The number of viable bacteria on the first day of Example 3 was 24.1*10 7 CFU / mL, the number of viable bacteria on the 28th day was 4.2*10 7 CFU / mL.

[0133] On the 28th day, the number of viable lactic acid bacteria in the product still exceeded 10 6 CFU / mL, which meets the requirements for yogurt products specified in international standards.

[0134] 2) Changes in water holding capacity

[0135] Water holding capacity refers to the ability of a sample to retain water. High water holding capacity indicates a stable gel structure and good product stability.

[0136] The determination method is the centrifugation method: take a certain amount of the sample after ripening for one day (such as 10-20g) and put it into a centrifuge tube, and record the initial weight of the sample m1. Put the centrifuge tube into the centrifuge, set the appropriate centrifugal speed (such as 3000-5000r / min) and centrifugal time (10-20min). After the centrifugation is completed, take out the centrifuge tube and let it stand for a while. Pour out the supernatant and measure the weight of the remaining sediment m2. The water holding capacity calculation formula is: water holding capacity (%) = (m2 / m1) × 100%.

[0137] Depend on Figure 3It can be seen that the water holding rate of Example 1 is 62.95%, the water holding rate of Example 2 is 75.2%, and the water holding rate of Example 3 is 81.95%.

[0138] Among them, Example 3, in which the soy milk content in the raw materials was the highest, had the highest water holding rate, indicating the potential of the obtained double-protein yogurt with a high soy milk content in terms of stability.

[0139] 3) Changes in acidity

[0140] The prepared product was stored at 4°C and its acidity was tested. Acidity affects the taste of the product. The formation of organic acids can inhibit the growth of bacteria in the product. The higher the acidity, the higher the metabolic adaptability of lactic acid bacteria to the nutrients (such as proteins and sugars) in the product matrix, thereby producing more organic acids. However, too high acidity will affect the palatability of the product.

[0141] like Figure 4 As shown, with the extension of storage time, the acidity of the products showed an upward trend. The acidity of Example 1 on the first day of storage was 48.97°T, and the acidity on the 28th day was 74.64°T. The acidity of Example 2 on the first day of storage was 48.75°T, and the acidity on the 28th day was 71.07°T. The acidity of Example 3 on the first day of storage was 41.88°T, and the acidity on the 28th day was 70.63°T. It is within an acceptable range.

[0142] 4) Sensory evaluation

[0143] The taste and flavor of the product were evaluated using a comprehensive sensory scoring method: 10 experienced assessors were invited to conduct sensory scoring on the test samples. The scoring criteria were modified based on the requirements of GB19302-2010 "National Food Safety Standard Fermented Milk", with reference to the sensory scoring criteria for yogurt and in light of actual conditions, as shown in Table 1.

[0144] Table 1 Sensory evaluation criteria for double protein yogurt

[0145]

[0146] The sensory evaluation results are as follows Figure 5 As shown, the products of each embodiment have high scores in various items, and are generally good in color and flavor, taste, whey precipitation, and tissue state, and can meet the needs of consumers.

[0147] 5) Texture changes

[0148] The hardness, elasticity and toughness of the products obtained in each embodiment were tested. Figure 6The hardness, elasticity and toughness of each embodiment vary with the ratio of soy milk to milk. The ingredients in soy milk and milk are quite different. The change in ratio directly changes the ingredients of the mixed emulsion, which may change the protein composition and structure of the food, thereby affecting its hardness, elasticity and toughness, causing certain changes in the texture data of the product.

[0149] But in general, the texture data of the products obtained in various embodiments can meet the requirements as commercial products.

[0150] Comparative Example

[0151] The preparation method of this comparative example is basically the same as that of Example 1, except that only commercial bacteria (a mixed fermentation strain of Lactobacillus delbrueckii subspecies bulgaricus and Streptococcus thermophilus in a ratio of 1:1) are used for fermentation.

[0152] The preparation method of the double-protein yogurt of this comparative example comprises the following steps:

[0153] Soaking beans: Weigh 5kg of soybeans and soak them in cold water at a soybean-water ratio of 1:4 for 8 hours;

[0154] Grinding: Grind the beans in a high-concentration fine grinder at a bean-water ratio of 1:1 (w / w, based on dry beans);

[0155] Soybean milk cooking: using an integrated soybean milk cooking machine to cook the soybean milk to obtain cooked soy milk;

[0156] Filtration: The cooked soy milk is initially filtered using a centrifuge with a 200-mesh screen; drinking water is added to dilute the cooked soy milk to a concentration of 7°Bx;

[0157] Preparation: Mix cooked soy milk and milk, with the weight ratio of soy milk to pure milk being 3:7; add sucrose, with the added amount being 9wt% of the sum of the weight of soy milk and pure milk;

[0158] Pasteurization: The slurry obtained above was sterilized at 85°C for 20 min;

[0159] Inoculation: The concentration of commercial bacteria is 10 8 cfu / mL of fermentation broth, inoculate 20mL per liter of slurry;

[0160] Fermentation: The inoculated slurry was placed at 37°C for 8 hours;

[0161] Post-ripening and refrigeration: The fermented double-protein yogurt is post-ripened at 4° C. for 12 hours to obtain the double-protein fermented yogurt.

[0162] The resulting product is in a flowing state and cannot be scooped up in one piece. It is milky white in color, has a uniform and smooth texture, has a small amount of whey precipitated, has a strong flavor, and has a strong beany smell. Using only commercial bacteria to ferment dairy products containing more plant ingredients does not have a good coagulation effect.

[0163] The protein content of double-protein yogurt was tested in accordance with GB5009.5-2016, and the protein content was 3.12±0.21g / 100g.

[0164] Example 4

[0165] The preparation method of this example is basically the same as that of Example 1, except that only Weissella confusaSY628 is used for fermentation.

[0166] The preparation method of the double-protein yogurt of the present embodiment comprises the following steps:

[0167] Soaking beans: Weigh 5kg of soybeans and soak them in cold water at a soybean-water ratio of 1:4 for 8 hours;

[0168] Grinding: Grind the beans in a high-concentration fine grinder at a bean-water ratio of 1:1 (w / w, based on dry beans);

[0169] Soybean milk cooking: using an integrated soybean milk cooking machine to cook the soybean milk to obtain cooked soy milk;

[0170] Filtration: The cooked soy milk is initially filtered using a centrifuge with a 60-mesh screen; drinking water is added to dilute the cooked soy milk to a concentration of 7°Bx;

[0171] Preparation: Mix cooked soy milk and milk, with the weight ratio of soy milk to pure milk being 3:7; add sucrose, with the added amount being 9wt% of the sum of the weight of soy milk and pure milk;

[0172] Pasteurization: The slurry obtained above was sterilized at 85°C for 20 min;

[0173] Inoculation: The concentration of Weissella confusa SY628 was 10 8 cfu / mL of fermentation broth, inoculate 20mL per liter of slurry;

[0174] Fermentation: The inoculated slurry was placed at 37°C for 8 hours;

[0175] Post-ripening and refrigeration: The fermented double-protein yogurt is post-ripened at 4° C. for 12 hours to obtain the double-protein fermented yogurt.

[0176] The obtained double-protein yogurt product is a solidified state that can be scooped up in blocks, has a milky white color, a fine and smooth texture, no granular or rough feeling, smells fruity, has no obvious bean smell, and has no whey precipitation.

[0177] The protein content of yogurt was tested in accordance with GB5009.5-2016, and the protein content was 3.42±0.19g / 100g.

[0178] Reference example

[0179] Weissella confusa SY628 is a strain selected by the inventor from sour soy milk, which was accidentally obtained by the inventor in the Hunan Provincial Key Laboratory of Soy Products Processing and Safety Control of Shaoyang University. It is a solidified sour soy milk made by natural fermentation of soy milk. After fermentation test verification, it was confirmed that Weissella confusaSY628 is the key strain that transforms soy milk into solidified sour soy milk in the natural fermentation.

[0180] See also Figure 7 :The cell morphology of Weissella confusa SY628 is as follows Figure 7 As shown in the left figure, the bacteria are short rod-shaped, arranged singly or in pairs, and Gram-positive; the colony morphology of Weissella confusa SY628 on MRS solid medium supplemented with 2% calcium carbonate is as follows Figure 7 As shown in the middle picture, the colonies are milky white, opaque, round, with irregular edges, flat and not raised; the colony morphology of Weissella confusa SY628 on mMRS solid medium is as follows Figure 7 As shown in the right picture, the colony morphology is transparent and mucus-like, and appears to be stringy when picked up, indicating that the strain produces a high amount of viscous polysaccharides.

[0181] The fusion Weissella SY628 was deposited on September 19, 2024 in the General Microbiology Center of the China Culture Collection Administration (CGMCC for short, address: Institute of Microbiology, Chinese Academy of Sciences, No. 1 Beichen West Road, Chaoyang District, Beijing, China), and the culture collection number is CGMCC No.32006.

Claims

1. A method for making double protein yogurt, characterized in that: The mixed emulsion is fermented by fermentation bacteria; the main components of the mixed emulsion are plant-based milk and animal milk; and the fermentation bacteria include Weissella fusion.

2. The method for making double-protein yogurt according to claim 1, characterized in that: The number of live bacteria inoculated per liter of mixed emulsion is equivalent to inoculating 5-60mL of bacteria with a concentration of 10 6 -10 10 cfu / mL of fermentation broth.

3. The method for making double-protein yogurt according to claim 1, characterized in that: The fermentation bacteria include fused Weissella SY628, or the fermentation bacteria include fused Weissella SY628 and yogurt fermentation bacteria.

4. The method for making double-protein yogurt according to claim 3, characterized in that: The relationship between the inoculation volume of fusion Weissella SY628 and the mixed emulsion is: the number of viable bacteria of fusion Weissella SY628 inoculated per liter of mixed emulsion is equivalent to the number of live bacteria inoculated with 5-60mL of bacteria with a concentration of 10 6 -10 10 cfu / mL of fermented liquid; the relationship between the inoculation amount of yogurt fermentation bacteria and the amount of animal milk in the mixed emulsion is: the number of live yogurt fermentation bacteria inoculated with one liter of animal milk is equivalent to inoculating 5-60mL of bacterial cell concentration of 10 6 -10 10 cfu / mL of fermentation broth.

5. The method for making double-protein yogurt according to any one of claims 1 to 4, characterized in that: The fermentation temperature is 28-45°C; the fermentation time is 6-12 hours; the concentration of the plant-based milk is 6-9°Bx; the solid particle size in the plant-based milk is less than 60 mesh, preferably less than 200 mesh; the plant-based milk is a seed-based plant-based milk, preferably one or more of nut-based plant-based milk, grain-based plant-based milk, and bean-based milk.

6. The method for making double-protein yogurt according to any one of claims 1 to 4, characterized in that: After fermentation, it is also ripened: kept warm at 2-5°C for 12-48 hours.

7. The method for making double-protein yogurt according to any one of claims 1 to 4, characterized in that: Edible carbon sources are also added to promote fermentation.

8. The method for making double-protein yogurt according to claim 7, characterized in that: The edible carbon source is one or more of sucrose, glucose, fructose, galactose, lactose, oligosaccharides and polysaccharides; the weight of the edible carbon source used is 6% to 12% of the sum of the weight of plant-based milk and animal milk.

9. The method for making double-protein yogurt according to any one of claims 1 to 4, characterized in that: The weight ratio of plant-based milk to animal milk is 1:9 to 9:

1.

10. The method for making double-protein yogurt according to any one of claims 1 to 4, characterized in that: The mixed emulsion is also subjected to pressure homogenization.

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