Preparation method of set plant-based yoghurt

Abstract

The invention relates to a preparation method of solidified plant-based yoghourt. The plant-based yoghourt is fermented by adopting zymophyte; the zymophyte comprises fusion Weissella. The set plant-based yogurt can be prepared without adding any stabilizer, the product is smooth and elastic, whey is not separated out after demulsification and in the whole storage period, and the yogurt is fine and smooth when being eaten; within the preservation period of 21 days, the acidity change has no significant difference, and post-acidification is stable; the product is light in smell and free of unpleasant bad flavors such as fishy smell; the technical blank that the solidified plant-based yoghourt cannot be obtained only by fermentation of zymophyte at present is filled.

Description

Technical Field

[0001] The invention relates to a method for making plant yogurt, in particular to a method for making solidified plant-based yogurt. Background Art

[0002] Due to lactose intolerance, flexible dietary choices, environmental and health issues, as people's living conditions improve, people are paying more and more attention to food nutrition and health, and traditional dairy products are increasingly difficult to meet the demand. Plant-based dairy products are becoming more and more popular as an alternative.

[0003] However, compared with traditional animal milk, plant-based dairy products also have some defects, such as the presence of allergens, more difficult to digest, possible intestinal flatulence, unacceptable taste, etc. The above problems may be better solved through lactic acid bacteria fermentation. Protein aggregation during the fermentation process can change the protein structure that causes allergies, thereby eliminating allergens; it consumes the content of oligosaccharides that cause flatulence, and can produce organic acids, which can inhibit the growth of intestinal saprophytes, have anti-cancer effects, improve human gastrointestinal function, enhance immune function and lower serum cholesterol; the production of flavor substances through fermentation can change the flavor of plant-based dairy products. However, the ingredients of plant-based dairy products are quite different from those of traditional animal milk, and traditional yogurt fermentation bacteria have poor adaptability to plant-based dairy products. The resulting fermented products have problems such as poor stability, easy precipitation of whey, and bad taste, and satisfactory products cannot be obtained. 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 a coagulated plant-based yogurt without adding a stabilizer.

[0005] The technical solution adopted by the present invention to solve its technical problem is as follows: a method for making a solidified plant-based yogurt, fermenting plant-based milk with fermentation bacteria; the fermentation bacteria include Weissella fusion.

[0006] Preferably, the number of live bacteria inoculated per liter of plant-based milk is equivalent to that of 5-60 mL of fermentation 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 number of viable bacteria of Weissella SY628 inoculated per liter of plant-based milk is equivalent to that of 5-60 mL of bacteria with a concentration of 10 6 -10 10 cfu / mL of fermentation broth.

[0009] Preferably, the fermentation temperature is 28-45°C.

[0010] Preferably, the fermentation time is 6 to 12 hours.

[0011] Preferably, after fermentation, post-ripening is performed: keeping warm at 2-5°C for 12-48 hours.

[0012] Preferably, the concentration of the plant-based milk is 6-9° Bx.

[0013] Preferably, the particle size of the solid particles in the plant-based milk is less than 60 mesh.

[0014] Preferably, the particle size of the solid particles in the plant-based milk is less than 140 mesh.

[0015] Preferably, an edible carbon source is also added to promote fermentation.

[0016] Preferably, the edible carbon source is one or more of sucrose, glucose, lactose, galactose, fructose, oligosaccharides and polysaccharides.

[0017] Preferably, the edible carbon source is sucrose and / or lactose.

[0018] Preferably, the added amount of the edible carbon source is 6wt% to 12wt% of the weight of the plant-based milk.

[0019] Preferably, the plant-based milk is seed-based plant-based milk; more preferably, it is one or more of nut-based plant-based milk, cereal-based plant-based milk, and bean-based plant-based milk.

[0020] The present invention has the following beneficial effects: the present invention can produce a solidified plant-based yogurt without adding any stabilizer, the product is smooth and elastic, no whey is precipitated after demulsification and during the entire storage period, and the product is delicate and smooth when put into the mouth; during the 21-day storage period, there is no significant difference in the change of acidity, and the product is stable after acidification; the product has a light smell and no unpleasant fishy smell or other bad flavors; it fills the technical gap that solidified plant-based yogurt cannot be obtained by fermentation of fermentation bacteria alone. Since no expensive additives such as stabilizers are required, the product has obvious cost advantages.

[0021] 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.

[0022] Description of microbial preservation:

[0023] 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

[0024] 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:

[0025] Figure 1 The photos of the plant-based yogurt obtained by fermenting pure Weissella confusa SY628 in Example 2 of the present invention are as follows: (A) upright shape; (B) inverted shape; (C) cross-sectional shape after demulsification;

[0026] Figure 2 This is a photograph of the cross section of the plant-based yogurt obtained by fermentation with pure commercial bacteria after demulsification;

[0027] Figure 3 1 is a graph showing changes in pH values ​​of plant-based yogurt obtained in Example 1, Example 2, and Comparative Example during storage;

[0028] Figure 4 is a graph showing changes in titratable acidity (°T) of the plant-based yogurts obtained in Example 1, Example 2, and the comparative example during storage;

[0029] Figure 5 is a graph showing changes in the number of viable bacteria in the plant-based yogurts obtained in Example 1, Example 2, and the comparative example during storage;

[0030] Figure 6 It is a water retention test result diagram of the plant-based yogurt obtained in Example 1, Example 2 and Comparative Example after being stored at 4° C. for 7 days;

[0031] Figure 7 It is a hardness test result diagram of the plant-based yogurt obtained in Example 1, Example 2, and Comparative Example;

[0032] Figure 8 It is a storage modulus diagram of the plant-based yogurt obtained in Example 1, Example 2, and Comparative Example at different oscillation frequencies;

[0033] Fig. 9 is a Venn diagram of overlapping numbers of plant-based yogurt flavor substances obtained in Example 1, Example 2, and Comparative Example;

[0034] Fig.10These 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

[0035] 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.

[0036] 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.

[0037] 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.

[0038] An embodiment of the present invention provides a method for making a solidified plant-based yogurt, wherein plant-based milk is fermented by fermentation bacteria; the fermentation bacteria include Weissella fusion.

[0039] The method for making a solidified plant-based yogurt provided by the embodiment of the present invention has the following advantages: the embodiment of the present invention can make a solidified plant-based yogurt without adding any stabilizer, the product is smooth and elastic, no whey is precipitated after demulsification and during the entire storage period, and it is delicate and smooth when eaten. During the 21-day storage period, there is no significant difference in the change of acidity, and it is stable after acidification; the product has a light smell and no unpleasant fishy smell. It fills the technical gap that it is currently impossible to obtain a solidified plant-based yogurt by fermentation alone; since no expensive additives such as stabilizers are required, the product has obvious cost advantages.

[0040] In the embodiment of the present invention, the number of live bacteria of fermentation bacteria inoculated per liter of plant-based milk is equivalent to that of 5-60 mL of bacteria with a concentration of 10 6 -10 10 cfu / mL of fermentation broth.

[0041] In an embodiment of the present invention, the fermentation bacteria include Weissella fusion SY628.

[0042] In the embodiment of the present invention, the number of viable bacteria of Weissella SY628 inoculated per liter of plant-based milk is equivalent to that of 5-60 mL of bacteria with a concentration of 10 6 -10 10 cfu / mL of fermentation broth.

[0043] 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.

[0044] 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.

[0045] In an embodiment of the present invention, the fermentation temperature is 28-45°C.

[0046] In an embodiment of the present invention, the fermentation time is 6 to 12 hours.

[0047] In the embodiment of the present invention, after fermentation, post-ripening is further performed: keeping warm at 2-5° C. for 12-48 hours.

[0048] In an embodiment of the present invention, the concentration of the plant-based milk is 6-9° Bx.

[0049] 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, the plant-based milk contains more slag, and the taste itself is poor. The corresponding products are rare on the market. 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 into soluble), the particle size of the solid particles in the plant-based milk can be larger, and a smooth and delicate product can be obtained even if it contains a certain amount of slag. Moreover, the product is rich in fiber and has better nutritional value.

[0050] In some embodiments of the present invention, the particle size of the solid particles in the plant-based milk is less than 140 mesh, and the product obtained under this condition has a fine texture.

[0051] 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.

[0052] In some embodiments 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.

[0053] In some embodiments of the present invention, the edible carbon source is one or more of sucrose, glucose, lactose, galactose, fructose, oligosaccharides and polysaccharides.

[0054] In some embodiments of the present invention, the edible carbon source is sucrose and / or lactose.

[0055] In some embodiments of the present invention, the added amount of the edible carbon source is 6 wt % to 12 wt % of the weight of the plant-based milk.

[0056] 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.

[0057] In some embodiments of the present invention, the plant-based milk is seed-based milk.

[0058] 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.

[0059] Leguminous plants play an important role as one of the raw materials for the production of plant-based dairy products. They are rich in protein, complex carbohydrates, vitamins and fiber, making beans an ideal substitute for dairy products. Their yogurt products have great commercial value, but due to the large difference in composition from traditional animal milk, traditional yogurt fermentation bacteria have poor adaptability to them. The resulting fermented products have problems such as poor stability, easy whey precipitation, and bad taste, and satisfactory products cannot be obtained. There are no successful sour soy milk products on the market, especially coagulated sour soy milk without additional stabilizers.

[0060] In some embodiments of the present invention, the plant-based milk is cooked soy milk.

[0061] In some embodiments of the present invention, the method for making cooked soy milk comprises: soaking raw materials and then grinding them to obtain bean paste, removing bean dregs from the bean paste to obtain raw soy milk, and boiling the paste to obtain cooked soy milk.

[0062] In some embodiments of the present invention, the raw material soaking time is more than 8 hours.

[0063] In some embodiments of the present invention, the pulping is performed by micro-pressure pulping at 102-105° C. for 5-15 minutes.

[0064] In some embodiments of the present invention, the bean raw material in the cooked soy milk is one or more of soybeans, black beans, green beans, mung beans, red beans, kidney beans, peas, broad beans, lentils, and chickpeas.

[0065] In some embodiments of the present invention, the bean raw material in the cooked soy milk is soybeans.

[0066] In some embodiments of the present invention, the raw soy milk and / or cooked soy milk is further subjected to a pressure homogenization process.

[0067] 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.

[0068] 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 fermented plant-based yogurt uses a newly screened high-yield extracellular polysaccharide fusion Weissella, which can efficiently produce lactic acid while being able to 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, restricting the flow of water, thereby reducing whey precipitation and improving the stability of the gel. This water retention mechanism not only enhances the texture of plant-based yogurt, but also reduces the need for exogenous thickeners or stabilizers.

[0069] 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 the fermentation bacteria, which causes the plant protein to gel during the fermentation process, so that the produced exopolysaccharides are cross-linked with the 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 the fused Weissella SY628 very suitable as a fermentation bacteria for plant-based milk.

[0070] Example

[0071] 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.

[0072] The commercial bacteria used in the following examples and comparative examples are a mixed bacterial agent of Lactobacillus delbrueckii subspecies bulgaricus and Streptococcus thermophilus in a ratio of 1:1 produced by Chr. Hansen of Denmark, which is one of the most classic bacterial combinations for making yogurt.

[0073] Example 1

[0074] The method for making the solidified plant-based yogurt of this embodiment comprises the following steps:

[0075] Soaking beans: Weigh 5kg of soybeans and soak them in cold water for 8 hours at a mass ratio of 1:4;

[0076] Grinding: Mix the beans with water at a ratio of 1:1 (w / w, based on dry beans) and grind in a high-concentration fine grinder;

[0077] Boiling: Steam heating, boiling at 102℃ for 15min;

[0078] Filtration: Filter through a 140-mesh vibrating screen; dilute with drinking water until the cooked soy milk concentration is 7°Bx;

[0079] Preparation: adding sucrose to the soy milk, the weight of the sucrose used being 7% of the weight of the soy milk;

[0080] Sterilization: pasteurization is adopted at 85℃ for 20min;

[0081] Inoculation: Mix commercial bacteria with Weissella confusa SY628 (1:1) to make a bacterial concentration of 10 8 cfu / mL of fermented bacterial liquid, inoculate 30mL per liter of soy milk;

[0082] Fermentation: Place the inoculated liquid at 35°C for 7.5 hours;

[0083] Post-ripening and refrigeration: After fermentation is completed, post-ripen at 4°C for 12 hours to obtain mixed bacteria fermented plant-based yogurt (sour soy milk).

[0084] The obtained solidified plant-based yogurt product is milky white in color, has a smooth and flat surface, a fine texture, smells fruity, has no bean smell, and no obvious whey or water is analyzed out.

[0085] The protein content of plant-based yogurt was tested in accordance with GB5009.5-2016, and the measured protein content was 4.01±0.1g / 100g.

[0086] Example 2

[0087] The method for making the solidified plant-based yogurt of this embodiment comprises the following steps:

[0088] Soaking beans: Weigh 5kg of soybeans and soak them in cold water for 8 hours at a mass ratio of 1:4;

[0089] Grinding: Mix the beans with water at a ratio of 1:1 (w / w, based on dry beans) and grind in a high-concentration fine grinder;

[0090] Boiling: Steam heating, boiling at 102℃ for 15min;

[0091] Filtration: Filter through a 140-mesh vibrating screen; dilute with drinking water until the cooked soy milk concentration is 7°Bx;

[0092] Preparation: adding sucrose to the soy milk, the weight of the sucrose used being 7% of the weight of the soy milk;

[0093] Homogenization: high pressure homogenization is performed at 20MPa;

[0094] Sterilization: pasteurization is adopted at 85℃ for 20min;

[0095] Inoculation: The concentration of Weissella confusa SY628 was 10 8 cfu / mL of fermented bacterial liquid, inoculate 20mL per liter of soy milk;

[0096] Fermentation: Place the inoculated liquid at 35°C for 7.5 hours;

[0097] Post-ripening and refrigeration: After fermentation is completed, post-ripen at 4°C for 12 hours to obtain pure Weissella confusa SY628 bacterial strain fermented plant-based yogurt (sour soy milk).

[0098] The obtained solidified plant-based yogurt product is milky white in color, has a fine and smooth texture, has no granular or rough feeling, smells like a fresh cucumber, has no obvious bean smell, and has no whey precipitation.

[0099] The protein content of plant-based yogurt was tested in accordance with GB5009.5-2016, and the measured protein content was 4.32±0.09g / 100g.

[0100] The photo of the plant-based yogurt obtained by fermenting pure Weissella confusa SY628 in this example is shown in FIG. Figure 1 As shown in the figure, (A) upright shape; (B) inverted shape; (C) cross-sectional shape after demulsification. As can be seen from the figure, the plant-based yogurt obtained by pure Weissellaconfusa SY628 fermentation is milky white in color, with a fine and smooth texture, no granular or rough feeling, very good coagulation, does not fall when inverted, and no whey or water is separated out after demulsification.

[0101] Comparative Example

[0102] The preparation method of the plant-based yogurt of this comparative example comprises the following steps:

[0103] Soaking beans: Weigh 5kg of soybeans and soak them in cold water for 8 hours at a mass ratio of 1:4;

[0104] Grinding: Mix the beans with water at a ratio of 1:1 (w / w, based on dry beans) and grind in a high-concentration fine grinder;

[0105] Boiling: Steam heating, boiling at 102℃ for 15min;

[0106] Filtration: Filter through a 140-mesh vibrating screen; dilute with drinking water until the cooked soy milk concentration is 7°Bx;

[0107] Preparation: adding sucrose to the soy milk, the weight of the sucrose used being 9% of the weight of the soy milk;

[0108] Homogenization: high pressure homogenization is performed at 20MPa;

[0109] Sterilization: pasteurization is adopted at 85℃ for 20min;

[0110] Inoculation: The concentration of commercial bacteria is 10 8 cfu / mL of fermented bacterial liquid, inoculate 30mL per liter of soy milk;

[0111] Fermentation: Place the inoculated liquid for fermentation at 37°C for 8 hours;

[0112] Post-ripening and refrigeration: The fermented liquid is placed at 4°C for post-ripening for 12 hours to obtain commercial bacterial fermented plant-based yogurt (sour soy milk).

[0113] The obtained plant-based yogurt product is milky white in color, has a relatively uniform texture, is in a coagulated state, and smells like yogurt with a mixed bean smell. After demulsification and stirring, water whey or analysis is relatively serious.

[0114] The protein content of plant-based yogurt was tested in accordance with GB5009.5-2016, and the protein content was 3.17±0.07g / 100g.

[0115] Comparative Example: The cross-section of the plant-based yogurt obtained by fermentation with pure commercial bacteria after demulsification is shown in the figure below. Figure 2 As shown in the figure, it can be seen that the plant-based yogurt obtained by pure commercial bacteria fermentation has serious whey precipitation after demulsification, and the texture is not as delicate as the product obtained in Example 2 of the present invention.

[0116] Example 3

[0117] The method for making the solidified plant-based yogurt of this embodiment comprises the following steps:

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

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

[0120] Boiling: Steam heating, boiling at 102℃ for 15min;

[0121] Filtration: Filter through a 60-mesh vibrating screen; dilute with drinking water until the cooked soy milk concentration is 7°Bx;

[0122] Preparation: adding sucrose to the soy milk, the weight of the sucrose used being 9% of the weight of the soy milk;

[0123] Sterilization: pasteurization is adopted at 85℃ for 20min;

[0124] Inoculation: The concentration of Weissella confusa SY628 was 10 8 cfu / mL of fermented bacterial liquid, inoculate 20mL per liter of soy milk;

[0125] Fermentation: Place the inoculated liquid for fermentation at 42°C for 8.5 hours;

[0126] Post-ripening and refrigeration: the fermented liquid was post-ripened at 4°C for 12 hours to obtain pure Weissella confusa SY628 bacterial strain fermented plant-based yogurt (sour soy milk).

[0127] The obtained solidified plant-based yogurt product is milky white in color, has a fine and smooth texture, has no granular or rough feeling, smells like a fresh cucumber, has no obvious bean smell, and no water is analyzed out.

[0128] The protein content of plant-based yogurt was tested in accordance with GB5009.5-2016, and the measured protein content was 4.73±0.21g / 100g.

[0129] Detection and analysis

[0130] The obtained plant-based yogurt was further analyzed for physical and chemical indicators. SYCHS is used to refer to the plant-based yogurt obtained in Example 1 (fermented with Weissella confusa SY628 + mixed commercial bacteria), SY628 is used to refer to the plant-based yogurt obtained in Example 2 (fermented with pure Weissella confusa SY628), and CHS is used to refer to the plant-based yogurt obtained in the comparative example (fermented with pure commercial bacteria).

[0131] 1) The prepared plant-based yogurt was stored at 4°C and its changes were tested.

[0132] 1.1) Changes in pH

[0133] like Figure 3 As shown, with the increase of storage time, the pH value showed a downward trend, the pH value of SYCHC was higher than that of CHS, and the pH value of SY628 was the highest, but the overall difference in pH values ​​among the three samples was not significant.

[0134] Lactic acid bacteria can use carbohydrates for growth, reproduction and metabolism, resulting in a continuous decrease in pH. The significant difference in pH between days 1 and 21 may be due to the continuous fermentation of lactic acid bacteria in the yogurt and the conversion of lactose into lactic acid. In addition, the decrease in pH of the yogurt samples may be related to the enzymes produced by the starter during the fermentation process. After 21 days of storage, the reduction of the pH value of plant-based yogurt to around 4.5 is crucial to promote gel formation and reduce electrostatic repulsion between casein particles.

[0135] 1.2) Changes in acidity

[0136] The formation of organic acids can inhibit the growth of bacteria in the product, but too high acidity affects the taste of the product and causes unpalatability. Figure 4 As shown in the figure, the acidity values ​​of plant-based yogurt fermented with three different starter cultures all showed an upward trend. The reason is that during the fermentation process, Weissella confusa SY628 and commercial bacteria use sugars to produce lactic acid. The continuous production of lactic acid causes the acidity to gradually increase.

[0137] Among them, SY628 has the lowest acidity, which is 78.85±0.78°T on the 21st day of storage; CHS has the highest acidity, which reaches 89.90±1.27°T on the 21st day of storage; SYCHS has a lower acidity than CHS and a higher acidity than SY628, with an acidity of 81.15±0.91°T on the 21st day of storage. It can be seen that commercial lactic acid bacteria can make the acidity of plant-based yogurt rise faster, causing severe post-acidification and affecting the palatability of the product. W.confuse SY628 can maintain the acidity of plant-based yogurt at a lower level, solving the problem of severe post-acidification during the fermentation process of plant-based yogurt.

[0138] 1.3) Number of viable bacteria

[0139] The changes in microbial counts can directly reflect the growth of probiotics in fermented milk during refrigeration. Figure 5 As shown in the figure, during the storage process, the total colony count first increased and then decreased. It may be that the lactic acid bacteria in the fermented milk continued to grow during the storage process and metabolized the nutrients remaining in the acidic milk. The number of live bacteria was the highest on the 7th day of storage, when the bacteria were in the growth stage. After the 7th day, due to the decrease in pH value and the significant increase in acidity, the growth of bacteria may be hindered, resulting in acid stress, and the number of live lactic acid bacteria showed a downward trend. However, on the 21st day of storage, the number of live lactic acid bacteria in plant-based yogurt was still more than 10 6 CFU / mL, which meets the requirements for yogurt products specified in international standards.

[0140] 2) Water retention

[0141] The prepared plant-based yogurt was stored at 4°C for 7 days and then tested for its water retention. The better the water retention, the more stable the gel formed, and the less likely the product will have whey precipitation.

[0142] Depend on Figure 6 It can be seen that SY628 has the highest water retention, and the water retention of SYCHS fermented by mixed bacteria is also significantly higher than that of CHS fermented by commercial bacteria (P<0.05). The better the coagulation of the product, the better the water retention, and the less whey precipitation of the product during storage.

[0143] The water retention of SY628 and SYCHS is significantly better than that of CHS, indicating that the improvement in water retention is attributed to the fermentation bacteria Weissella fusion. The exopolysaccharides produced by fermentation bacteria are usually distributed near the pores in the gel network structure and have the ability to bind water, thereby increasing the water retention of the gel. Strong intermolecular interactions and the formation of a stable three-dimensional network in the protein-polysaccharide system give plant-based yogurt good water retention. The improvement in water retention of SY628 and SYCHS is directly related to the high production of exopolysaccharides by the used Weissella fusion.

[0144] 3) Hardness

[0145] The hardness of the obtained plant-based yogurt was tested. Texture characteristics are one of the important indicators for measuring the quality of plant-based yogurt. Hardness plays an important role in forming a coagulated product. Too low hardness will make the yogurt product fragile and unable to maintain a stable coagulated state. Figure 7 As shown in the figure, SY628 had the highest hardness, and SYCHS had a significantly higher hardness than the commercially fermented plant-based yogurt CHS (P<0.05). This may be because the fusion of Weissella increased the hardness by attaching the extracellular polysaccharide produced on the protein matrix; while during the gel formation process of plant-based yogurt, the number of intermolecular disulfide bonds formed by the exchange reaction of thiol and disulfide bonds by commercial lactic acid bacteria decreased, resulting in a lower hardness of plant-based yogurt.

[0146] 4) Rheological properties

[0147] The rheological properties of the obtained plant-based yogurt were tested: the storage modulus value of the obtained plant-based yogurt was tested at an oscillation frequency of 0 to 10 Hz. Figure 8 As shown in the figure, the storage modulus value G' of SY628 at each frequency is the highest, and the storage modulus value G' of SYCHS is also significantly higher than that of CHS (P<0.05), indicating that the gel network structure of SY628 and SYCHS is significantly stronger than that of CHS; the lower G' value of CHS indicates that its gel exhibits weaker elasticity and looser gel structure. A stronger gel network structure is essential for the formation of coagulated plant-based yogurt products. The stronger gel network structure of SY628 and SYCHS may be due to the fact that the fermentation bacteria used in the fusion of Weissella viscous polysaccharide have a higher viscosity, which strengthens the strength of the system network structure and the interaction between molecular chains.

[0148] 5.1) Flavor characteristics

[0149] The flavoromics of SY628, SYCHS, and CHS were compared and analyzed, and the results are shown in Table 1. In addition to alcohols, the types of volatile compounds such as ketones, hydrocarbons, heterocyclic compounds, aldehydes, and esters in SY628 are less than those in SYCHS, and even less than those in CHS. It can be seen that the product of soy milk fermented with Weissella fusion has a lighter and softer smell and less beany smell.

[0150] 5.2) Statistics of the number of flavor substances identified

[0151] The identification of flavor substances among different groups is shown using a Venn diagram, which shows the number of flavor substances specifically identified in one group and the number of flavor substances commonly identified in multiple groups. Fig. 9It can be seen that the number of flavor substances identified in the three sample groups is 700. CHS contains the most unique flavor compounds, a total of 762, while SY628 contains the least unique flavor compounds, only 546. This result is consistent with the sensory evaluation that SY628 has a lighter smell. The fermentation product of the fermentation bacteria fused with Weissella has a lighter smell and does not have an unpleasant bean smell.

[0152] Table 1 Flavor components of the obtained plant-based yogurt

[0153]

[0154] Reference example

[0155] 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.

[0156] See also Fig.10 :The cell morphology of Weissella confusa SY628 is as follows Fig.10 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 Fig.10 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 Fig.10 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.

[0157] 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 preparing a solidified plant-based yogurt, characterized in that: The plant-based milk is fermented by using fermentation bacteria; the fermentation bacteria include Weissella fusion.

2. The method for making the solidified plant-based yogurt according to claim 1, characterized in that: The number of live bacteria inoculated per liter of plant-based milk 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 the solidified plant-based yogurt according to claim 1, characterized in that: The fermentation bacteria include Weissella fusion SY628.

4. The method for making the solidified plant-based yogurt according to claim 1, characterized in that: The number of viable bacteria of Weissella SY628 inoculated per liter of plant-based milk is equivalent to inoculating 5-60mL of bacteria with a concentration of 10 6 -10 10 cfu / mL of fermentation broth.

5. The method for preparing the set-type plant-based 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.

6. The method for preparing the set-type plant-based 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 preparing the set-type plant-based yogurt according to any one of claims 1 to 4, characterized in that: The concentration of the plant-based milk is 6-9° Bx; the particle size of the solid particles in the plant-based milk is less than 60 mesh, preferably less than 140 mesh.

8. The method for preparing the set-type plant-based yogurt according to any one of claims 1 to 4, characterized in that: Edible carbon sources are also added to promote fermentation.

9. The method for making the solidified plant-based yogurt according to claim 8, characterized in that: The edible carbon source is one or more of sucrose, glucose, lactose, galactose, fructose, oligosaccharides and polysaccharides; the added amount of the edible carbon source is 6wt% to 12wt% of the weight of the plant-based milk.

10. The method for preparing the set-type plant-based yogurt according to any one of claims 1 to 4, characterized in that: The plant-based milk is seed-based plant-based milk; preferably one or more of nut-based plant-based milk, cereal-based plant-based milk, and bean-based plant-based milk.

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