Preparation method of flavored dried bean curd with good three-dimensional network structure and flavored dried bean curd

Abstract

The preparation method comprises the following steps: S1, taking yellow serofluid, filtering to remove bean dregs, adding 3% of glucose as a carbon source, carrying out high-temperature sterilization at 121 DEG C for 20 minutes, and cooling to room temperature; the method comprises the following steps: inoculating compound bacteria into sterilized yellow serofluid, simultaneously adding 0.1% of functional polysaccharide microcapsules as a strain immobilization carrier, culturing at 28-32 DEG C and pH value of 6.0-6.5 for 24 hours to obtain fermentation liquor, and after the culture is finished, centrifugally separating the fermentation liquor at 3000rpm for 10 minutes to obtain a coagulator; and S2, preparing the dried bean curd by using the obtained coagulator. The preparation method has the beneficial effects that the prepared dried bean curd has a good three-dimensional network structure and a good texture structure, and is high in protein content and rich in nutrition.

Description

Technical Field

[0001] The present invention relates to the field of dried tofu preparation, and more particularly to a preparation method of flavored dried tofu with a good three-dimensional network structure and the flavored dried tofu. Background Art

[0002] The formation and quality of tofu gel are closely related to the type of coagulant. Commonly used industrial tofu coagulants include gypsum, brine, salt coagulants (magnesium chloride, calcium chloride, magnesium sulfate), and acid coagulants (glucono-δ-lactone). Gypsum coagulants can make tofu tender, but excessive gypsum content can affect the taste. Brine can make tofu firm, but improper use can produce a bitter taste. Salt coagulants such as calcium chloride and magnesium chloride are suitable for making tender tofu, while the latter is suitable for making dried tofu and fried tofu. Acid coagulants such as glucono-δ-lactone produce soy products with good water retention but may have a slightly sour and astringent taste. Studies have found that magnesium chloride tofu has a higher critical strain and a higher gel strength than glucono-δ-lactone tofu, but its network structure is coarser.

[0003] Dried tofu made with Physalis alkekengi possesses a unique flavor and texture, making it a crucial method in traditional dried tofu production. Applying probiotics to soy products not only expands their application but also enhances their nutritional value. Physalis alkekengi, derived from the fermented yellow slurry from the tofu-making process, offers advantages such as environmental friendliness and safety. Currently, no research has been conducted on combining Lactobacillus plantarum, Saccharomyces cerevisiae, and yellow slurry in the production of dried tofu. Summary of the Invention

[0004] An object of the present invention is to solve at least the above problems and to provide at least the advantages which will be described hereinafter.

[0005] Another object of the present invention is to provide a preparation method of flavored dried tofu with a good three-dimensional network structure and the flavored dried tofu, wherein the flavored dried tofu has a good three-dimensional network structure and good texture, high protein content, and rich nutrition.

[0006] In order to achieve these objects and other advantages according to the present invention, a method for preparing flavored dried tofu having a good three-dimensional network structure is provided, comprising the following steps:

[0007] S1. Filter yellow pulp water to remove bean dregs, add 3% glucose as a carbon source, sterilize at 121° C. for 20 min, and then cool to room temperature; inoculate the composite bacteria into the sterilized yellow pulp water, add 0.1% functional polysaccharide microcapsules as a bacterial immobilization carrier, and culture at 28-32° C. and a pH value of 6.0-6.5 for 24 h to obtain a fermentation broth, centrifuge the fermentation broth at 3000 rpm for 10 min to obtain a coagulant for standby use; wherein the inoculation amount of the composite bacteria is 8-12%, and the composite bacteria include Lactobacillus plantarum and Saccharomyces cerevisiae at a bacterial count ratio of 1:1; the functional polysaccharide microcapsules are prepared from a TGase-sodium alginate mixture and a pectin solution;

[0008] S2. Accurately weigh a certain amount of soybeans, wash them with clean water, and soak them at room temperature for 12 hours. Rinse the soaked soybeans twice with water, grind them in a soymilk maker for 5 minutes, and filter them through nylon cloth to obtain residue-free soymilk. Boil the soymilk for 5 minutes and filter it again for later use. After the soymilk is cooled to 80° C., add the coagulant to the soymilk, stir evenly, place it in an 80° C. water bath and let it stand for 30 minutes. Pour it into a dried tofu mold, and press it with a weight to shape the dried tofu. The volume ratio of the coagulant to the soymilk is 1:3-5.

[0009] Preferably, in step S1, the preparation of the functional polysaccharide microcapsules is as follows:

[0010] TG enzyme is mixed with water to form a TG enzyme solution with a mass concentration of 8-12%; sodium alginate and pectin are mixed with water respectively to form a sodium alginate solution with a mass concentration of 2%-3% and a pectin solution with a mass concentration of 1%-2%, respectively; the TG enzyme solution and the sodium alginate solution are mixed to obtain a TG enzyme-sodium alginate mixed solution, the TG enzyme-sodium alginate mixed solution is treated with the pectin solution to form a composite wall material, and the functional polysaccharide microcapsules are obtained after drying; wherein the volume ratio of the TG enzyme solution to the sodium alginate solution is 1:1.

[0011] Preferably, the steps of treating the TG enzyme-sodium alginate mixture with the pectin solution to form a composite wall material, and drying to obtain the functional polysaccharide microcapsules are as follows:

[0012] Calcium chloride is dissolved in water to form a calcium chloride solution with a mass concentration of 2% to 3%; a TG enzyme-sodium alginate mixture is poured into an emulsifier or a high-pressure homogenizer, and a pectin solution is slowly added under a stirring speed of 1000 rpm to 2000 rpm to form an oil-in-water emulsion; the oil-in-water emulsion is transferred to a container containing a calcium chloride solution, and the container is allowed to stand at room temperature for 20 to 30 minutes to form gel microcapsules, and the gel microcapsules are filtered through a sieve to obtain the functional polysaccharide microcapsules.

[0013] Preferably, in step S1, a pulsed electric field is applied every 8 hours during the culture process, and the conditions of the pulsed electric field are: frequency 5-20 Hz, field strength 3-7 V / cm, and duration 2 minutes, so as to promote the metabolic activity of the bacteria and the production of secondary metabolites.

[0014] Preferably, the application of the pulsed electric field is carried out in three stages, as follows: in the 0-8h stage, a pulsed electric field with a frequency of 5 Hz and a field strength of 3 V / cm is applied for a duration of 2 min; in the 8-16h stage, a pulsed electric field with a frequency of 10 Hz and a field strength of 5 V / cm is applied for a duration of 2 min; in the 16-24h stage, a pulsed electric field with a frequency of 20 Hz and a field strength of 7 V / cm is applied for a duration of 2 min.

[0015] Preferably, step S1 is specifically as follows:

[0016] The method comprises the following steps: filtering yellow pulp water through a 200-mesh sieve, adding 0.5-1.2% whey protein powder and 0.3% yeast extract as nutritional supplements, sterilizing the water at 121° C. for 20 minutes, and cooling the water to 30° C.; inoculating Lactobacillus plantarum, Saccharomyces cerevisiae, and Lactobacillus brevis at a bacterial count ratio of 5:5:2, with a total inoculation amount of 8-12%, and adding 0.1% functional polysaccharide microcapsules as bacterial immobilization carriers; culturing the water at 28-32° C. and a pH value of 6.0-6.5 for 24 hours to obtain the fermentation liquid; and centrifuging the fermentation liquid at 3000 rpm for 10 minutes to obtain a coagulant for standby use.

[0017] Preferably, in step S2, the coagulant is added to the soy milk, stirred evenly, and placed in a water bath at 80° C. for 30 minutes to obtain tofu pudding, and the tofu pudding is poured into a tofu mold and then pressed with a weight to shape the tofu. The specific steps of pouring the tofu pudding into the tofu mold and then pressing with a weight to shape the tofu include:

[0018] A1. Evenly spread the tofu into a dried tofu mold. Pre-place food-grade silicone mats on the bottom and side walls of the mold.

[0019] A2. Cover the surface of the soybean curd with a food-grade breathable film with a pore size of 10-50 μm;

[0020] A3. Place a pressing plate on top of the breathable membrane. The surface of the pressing plate is provided with evenly distributed micro-protrusions with a height of 0.5 to 1 mm and a spacing of 5 to 10 mm to promote uniform drainage of moisture from the dried tofu.

[0021] A4. Apply a heavy object on the pressing plate to press. Adjust the pressure in stages during the pressing process. The initial pressure is 0.2 MPa, which lasts for 10 minutes. The middle pressure is 0.35 MPa, which lasts for 20 minutes. The final pressure is 0.5 MPa, which lasts for 10 minutes.

[0022] A5. After the pressing is completed, remove the weight and breathable film, take the formed dried tofu out of the mold, and place it in a ventilated environment to naturally cool to room temperature to obtain flavored dried tofu with a good three-dimensional network structure.

[0023] Preferably, in step S2, soybeans are weighed and washed, the water temperature is controlled at 25±2°C during washing, and 20kHz ultrasonic treatment is applied for 30 seconds between each washing; the washed soybeans are soaked in soft water containing 0.05mol / L sodium bicarbonate at a ratio of 1:3w / v, and intermittently soaked at 50r / min in a constant temperature oscillator at 25°C for 12h; the soaked soybeans are washed and crushed in two stages in a wall-breaking pulper preheated at 45°C: the first stage is coarse grinding at 8000rpm for 60 seconds, and the second stage is fine grinding at 12000rpm for 180 seconds, and 60°C water is added during grinding at a ratio of 1:18w / v; the obtained slurry is filtered through 200-mesh nylon cloth with centrifugal assistance, the centrifugal conditions are: 3000rpm, 5min, the filtrate is collected to obtain the residue-free soy milk, the residue-free soy milk is boiled in a step-by-step heating to inactivate the enzyme, and then terminally filtered through a three-layer composite filter membrane for standby use.

[0024] Preferably, the specific process of the step-by-step temperature increase and terminal filtration includes the following steps: pouring the residue-free soy milk into a heating device and heating and inactivating the enzyme in three stages: heating to 70°C and holding for 5 minutes with stirring, then heating to 85°C within 5 minutes and holding for 3 minutes, and finally heating to 100°C and holding for 5 minutes to obtain the enzyme-inactivated soy milk; filtering the enzyme-inactivated soy milk while hot with a three-layer filter, the first layer being an 80-mesh stainless steel screen, the second layer being a food-grade filter cloth with a pore size of 50 μm, and the third layer being ordinary coffee filter paper; and cooling the filtered soy milk to 80°C for use.

[0025] The invention discloses a method for preparing flavored dried tofu with good three-dimensional network structure and obtains flavored dried tofu.

[0026] The present invention has at least the following beneficial effects:

[0027] First, by using functional polysaccharide microcapsules as a carrier for bacterial immobilization, the metabolic activity of the bacteria and the production of secondary metabolites were significantly increased, thereby improving the flavor and texture of the dried tofu. Furthermore, the addition of a coagulant optimized the three-dimensional network structure of the dried tofu, making it denser and more stable.

[0028] Second, by optimizing the preparation method of functional polysaccharide microcapsules, the uniformity of the particle size and structure of the microcapsules was ensured, thereby improving their performance as a carrier for immobilizing bacterial strains and further enhancing the metabolic activity of the bacterial strains.

[0029] Third, by precisely controlling the particle size and structure of the microcapsules, their stability and effectiveness during the fermentation process are ensured, thereby improving the immobilization effect of the bacteria and the production of metabolites.

[0030] Fourth, by applying a pulsed electric field, the metabolic activity of the bacteria was significantly improved, and the production of secondary metabolites was promoted, thereby improving the flavor and nutritional value of the dried tofu.

[0031] Fifth, by applying pulsed electric fields in stages, the metabolic process of the bacteria is further optimized, ensuring the uniform generation of secondary metabolites, thereby improving the overall quality of the dried tofu.

[0032] Sixth, by adding whey protein powder and yeast extract as nutritional supplements, the growth rate and metabolic activity of the bacteria were significantly improved, thereby enhancing the performance of the coagulant.

[0033] Seventh, by optimizing the pressure distribution and moisture discharge method during the pressing process, the uniform discharge of moisture inside the dried tofu is ensured, thus forming a denser and more uniform three-dimensional network structure.

[0034] Eighth, ultrasonic-assisted cleaning is used to effectively destroy the cell wall structure of soybeans, thereby increasing the protein dissolution rate and decomposing trypsin inhibitors, significantly improving the digestion and absorption rate of dried tofu, and improving the protein extraction rate and quality: a two-stage wall-breaking grinding process (8000rpm coarse grinding + 12000rpm fine grinding) is used to reduce protein thermal denaturation, increase the cell wall breaking rate, and provide a high-purity matrix for subsequent gel network formation; centrifugal-assisted filtration (3000rpm×5min) combined with 200-mesh nylon cloth filtration reduces the turbidity of soy milk, ensuring that the dried tofu has a delicate texture without any graininess.

[0035] Ninth, the lipoxygenase is inactivated in stages by step-by-step heating (70℃→85℃→100℃), while retaining most of the natural globulin conformation. Compared with the direct boiling method, the gel strength is improved, and the uniformity of the three-dimensional network pores of the dried tofu is improved; common commercially available filter materials (80-mesh stainless steel screen + 50μm filter cloth + coffee filter paper) are used to replace professional membrane equipment. While reducing costs, the turbidity of soy milk and the amount of residual bean dregs are reduced, and the filtration speed is improved. It is suitable for small and medium-sized production and has good application prospects.

[0036] Tenth, the present invention provides a flavored dried bean curd with a good three-dimensional network structure. In the process of preparing the flavored dried bean curd: first, sodium alginate is used to encapsulate TG enzyme to prepare microcapsules, and then a pectin layer is encapsulated on the prepared microcapsules to prepare multifunctional microcapsules. When the multifunctional microcapsules are put into fermentation yellow water, the multifunctional microcapsules can serve as bacterial carriers, provide active sites for the composite bacterial strains, and promote the growth and metabolism of the composite bacterial strains. At the same time, some beneficial components produced by the composite bacterial strains during metabolism can also be embedded in the multifunctional microcapsules, and the beneficial components are slowly released during the subsequent soy milk coagulation process to promote Soy milk coagulant, and due to the sustained-release characteristics of the multifunctional microcapsules, the soy milk can be evenly solidified, thereby improving the texture properties of dried tofu; in addition, the core of the multifunctional microcapsules is embedded with TG enzyme. When the soy milk begins to solidify, the outer pectin and sodium alginate layers minimize the possibility of TG inactivation at high temperatures. At the same time, the small molecule beneficial components produced by the metabolism of the composite bacteria embedded in the pectin are gradually released, promoting the coagulation of the soy milk. When the soy milk gradually cools down, the outer pectin and sodium alginate gradually dissolve, and the TG enzyme is gradually released, cross-linking with the protein in the soy milk to form dried tofu with a good three-dimensional network structure.

[0037] Other advantages, objectives and features of the present invention will be reflected in part from the following description and will be understood by those skilled in the art through study and practice of the present invention. DETAILED DESCRIPTION

[0038] The present invention is further described in detail below with reference to the embodiments so that those skilled in the art can implement the invention with reference to the description.

[0039] The invention provides a method for preparing flavored dried tofu with a good three-dimensional network structure, comprising the following steps: S1, filtering yellow pulp water to remove bean dregs, adding 3% glucose as a carbon source, sterilizing at 121° C. for 20 minutes, and then cooling to room temperature; inoculating composite bacteria into the sterilized yellow pulp water, adding 0.1% functional polysaccharide microcapsules as bacteria immobilization carriers, culturing at 28-32° C. and a pH value of 6.0-6.5 for 24 hours to obtain a fermentation liquid, centrifuging the fermentation liquid at 3000 rpm for 10 minutes to obtain a coagulant for standby use; wherein the inoculation amount of the composite bacteria is 8-12%, and the composite bacteria include Lactobacillus plantarum and Saccharomyces cerevisiae at a bacterial count ratio of 1:1; the functional polysaccharide microcapsules are prepared from a TGase-sodium alginate mixed liquid and a pectin solution;

[0040] S2. Accurately weigh a certain amount of soybeans, wash them with clean water, and soak them at room temperature for 12 hours. Rinse the soaked soybeans twice with water, grind them in a soymilk maker for 5 minutes, and filter them through nylon cloth to obtain residue-free soymilk. Boil the soymilk for 5 minutes and filter it again for later use. After the soymilk is cooled to 80° C., add the coagulant to the soymilk, stir evenly, place it in an 80° C. water bath and let it stand for 30 minutes. Pour it into a dried tofu mold, and press it with a weight to shape the dried tofu. The volume ratio of the coagulant to the soymilk is 1:3-5.

[0041] In the above technical solution, the yellow slurry water is the yellow slurry water used in the tofu preparation process; when preparing the coagulant, the yellow slurry water can be filtered through a 200-mesh screen. Food-grade glucose can be used, with various brands available commercially. A high-pressure steam sterilizer can be used for high-temperature sterilization. Lactobacillus plantarum and Saccharomyces cerevisiae in the composite bacteria can be purchased from a professional microbial strain company. The inoculum size of the composite bacteria is 8-12%, with the specific inoculum size selected based on actual circumstances. For the preparation of functional polysaccharide microcapsules, TG enzyme, sodium alginate, and pectin are all commercially available food-grade products. Cultivation can be carried out in a constant-temperature incubator at temperatures of 28°C, 30°C, or 32°C, and the pH can be adjusted to 6.0, 6.2, or 6.5 using a pH adjuster. A standard laboratory centrifuge can be used for centrifugation. A yellow slurry water filtration device is installed above the container for filtration. The autoclave is used to sterilize the treated yellow slurry water. The incubator is set to the desired temperature and pH for culturing. The centrifuge is used to separate the fermentation broth to obtain the coagulant. First, filter the yellow pulp water to remove the dregs. Add 3% glucose (3% refers to a glucose to yellow pulp water mass ratio of 3:100). Stir thoroughly, then sterilize at high temperature. Cool to room temperature, inoculate the mixture with the composite bacteria and functional polysaccharide microcapsules, and incubate under specified conditions. After incubation, centrifuge to obtain the coagulant. Parameter settings are determined based on experimental experience and relevant research. Raw materials can be purchased from reputable food ingredient suppliers.

[0042] When preparing soymilk, choose high-quality, non-GMO soybeans. Soak the soybeans in ordinary water. Grind the soybeans using a home soymilk maker or specialized soy product grinding equipment. Filter the soymilk using nylon cloth, such as a 200-mesh cloth. Boil the soymilk in a standard pot or specialized soymilk grinding equipment. Soak the soybeans in clean water for 12 hours. Rinse and grind them in a grinding equipment. After grinding, filter the soybeans with nylon cloth, boil the soymilk, filter again, and cool until ready for use. The raw soybeans are commercially available. Other materials and equipment are readily available; simply follow the equipment's instructions.

[0043] When making dried tofu, the coagulant and soy milk can be mixed in a mixing vessel. A standard constant-temperature water bath can be used for an 80°C water bath. Molds can be made of food-grade plastic or stainless steel. Weights or other heavy objects can be used for compaction. Add the coagulant to the cooled soy milk and stir evenly. Place in a water bath and let it rest. Pour the mixture into the mold and place a weight on top to compact the tofu. Once compaction is complete, remove the tofu. Ensure the mold is clean and hygienic. Choose the appropriate mold for the desired size and shape of the tofu. Adjust the weight of the weight according to your needs to achieve the desired compaction effect.

[0044] In this technical solution, when used: first, prepare the coagulant. Filter the yellow slurry water with a sieve to remove the bean dregs, then add a certain amount of glucose into it and stir it thoroughly to dissolve the glucose. Then put the mixed liquid into a high-pressure steam sterilizer and sterilize it at 121°C for 20 minutes, and then wait for it to cool to room temperature. Prepare the composite bacteria and functional polysaccharide microcapsules, add them to the cooled yellow slurry water, place the mixed liquid in a constant temperature incubator, control the temperature at 28-32°C, adjust the pH value to 6.0-6.5, and culture for 24 hours. After the culture is completed, use a centrifuge to centrifuge at 3000rpm for 10 minutes to remove the bacteria, and the coagulant is obtained.

[0045] Next, prepare the soy milk. Select high-quality soybeans, wash them thoroughly with clean water, and soak them in clean water at room temperature for 12 hours. After soaking, rinse the soybeans twice more with clean water and grind them in a grinding machine for 5 minutes. Filter the ground soy milk through nylon cloth to obtain soy milk without any dregs. Pour the soy milk into a boiling pot and boil for 5 minutes. Then filter it again and let it cool to around 80°C before setting aside.

[0046] Finally, prepare the dried tofu. Add the previously prepared coagulant to the cooled soy milk and stir thoroughly. Then, place the soy milk in a constant-temperature water bath at 80°C for 30 minutes. Once the time is up, pour the soy milk into the prepared dried tofu mold and place a heavy object on top to press the mold into shape. Once the molding is complete, remove the formed dried tofu from the mold, resulting in flavored dried tofu with a well-defined three-dimensional network structure.

[0047] Technical Effect: This preparation method produces flavored dried tofu with a well-defined three-dimensional network structure. The use of a specific bacterial complex and functional polysaccharide microcapsules in the coagulant preparation process optimizes its performance. Multiple filtrations and optimal temperature control during soymilk preparation ensure its quality. Optimal conditions during the pressing process ensure a dense structure. The resulting dried tofu boasts a well-defined texture, enhanced taste, and a high protein content, enriching it with nutrients.

[0048] In another technical solution: in step S1, the preparation of the functional polysaccharide microcapsules is specifically as follows:

[0049] Mixing TG enzyme with water to form a TG enzyme solution with a mass concentration of 8-12%; mixing sodium alginate and pectin with water respectively to form a sodium alginate solution with a mass concentration of 2%-3% and a pectin solution with a mass concentration of 1%-2%, respectively; mixing the TG enzyme solution with the sodium alginate solution to obtain a TG enzyme-sodium alginate mixed solution, treating the TG enzyme-sodium alginate mixed solution with the pectin solution to form a composite wall material, and drying to obtain the functional polysaccharide microcapsules; wherein the volume ratio of the TG enzyme solution to the sodium alginate solution is 1:1;

[0050] The steps of treating the TG enzyme-sodium alginate mixture with the pectin solution to form a composite wall material, and drying to obtain the functional polysaccharide microcapsules are as follows:

[0051] Calcium chloride is dissolved in water to form a calcium chloride solution with a mass concentration of 2% to 3%; a TG enzyme-sodium alginate mixture is poured into an emulsifier or a high-pressure homogenizer, and a pectin solution is slowly added under a stirring speed of 1000 rpm to 2000 rpm to form an oil-in-water emulsion; the oil-in-water emulsion is transferred to a container containing a calcium chloride solution, and the container is allowed to stand at room temperature for 20 to 30 minutes to form gel microcapsules, and the gel microcapsules are filtered through a sieve to obtain the functional polysaccharide microcapsules.

[0052] In the above technical solution, when preparing the solution of functional polysaccharide microcapsules, a standard glass beaker can be used to dissolve TG enzyme, sodium alginate, and pectin. A glass rod or a small electric stirrer can be used for stirring and dissolving. The water used for dissolution can be distilled or deionized water. The mass concentration of the TG enzyme solution can be 8%, 10%, or 12%; the mass concentration of the sodium alginate solution can be 2%, 2.5%, or 3%; and the mass concentration of the pectin solution can be 1%, 1.5%, or 2%. The glass beaker is used to hold the solution, the stirrer is used to accelerate dissolution, and water is used as the solvent. TG enzyme, sodium alginate, and pectin are placed in separate glass beakers, and an appropriate amount of distilled or deionized water is added. Stir with a stirrer until completely dissolved to prepare a solution of the desired concentration. The raw materials TG enzyme, sodium alginate, and pectin can be purchased from chemical raw material suppliers. Follow the dissolution method specified in the product instructions and determine the solution concentration based on experimental requirements.

[0053] To prepare the TG enzyme-sodium alginate mixture, use a graduated cylinder to accurately measure the TG enzyme solution and sodium alginate solution. Pour the mixture into a new container, such as an Erlenmeyer flask, at a 1:1 volume ratio. Stir thoroughly with a stirrer. Graduated cylinders of varying sizes are available to accommodate different volume requirements. Use a graduated cylinder to measure both solutions, pour them into the Erlenmeyer flask, and stir thoroughly with a stirrer. Choose the appropriate graduated cylinder size based on the desired volume of mixture, and stir for a consistent mixing time.

[0054] When preparing functional polysaccharide microcapsules, the first step is to prepare a calcium chloride solution: dissolve calcium chloride in water to make a calcium chloride solution with a mass concentration between 2% and 3%. A glass beaker can be used to dissolve the calcium chloride, and a glass rod or small electric stirrer can be used for stirring. The water used for dissolution can be distilled water or deionized water. The mass concentration of the calcium chloride solution can be selected from 2%, 2.5%, or 3%. Place the glass beaker on a stable laboratory table to hold the solution, and place the stirrer in the solution to stir. Slowly add calcium chloride to a glass beaker filled with an appropriate amount of distilled or deionized water and stir with a stirrer until the calcium chloride is completely dissolved to prepare a solution of the appropriate concentration. The raw calcium chloride can be purchased from a chemical raw material supplier. Follow the dissolution method in the product manual and determine the solution concentration based on experimental requirements.

[0055] Next, pour the TG enzyme-sodium alginate mixture into an emulsifier or high-pressure homogenizer. Slowly add the pectin solution while stirring at a speed of 1000-2000 rpm to form an oil-in-water emulsion. The emulsion is then transferred to a container containing a calcium chloride solution and allowed to stand at room temperature for 20-30 minutes. During this time, the sodium alginate and calcium chloride undergo an ionic cross-linking reaction, forming gel microcapsules. After the reaction is complete, prepare a sieve of appropriate pore size and filter the microcapsule solution through it to remove excess calcium chloride solution. Finally, place the microcapsules in an oven to dry, resulting in the desired functional polysaccharide microcapsules. An emulsifier or high-pressure homogenizer is used to prepare the emulsion. Drying can be performed in an oven set at 40-60°C.

[0056] Instructions: First, prepare the solutions needed to prepare functional polysaccharide microcapsules. Take appropriate amounts of TG enzyme, sodium alginate, and pectin and place them in separate glass beakers. Add distilled or deionized water to each beaker and stir with a glass rod or small electric stirrer until completely dissolved. While stirring, carefully adjust the solution concentrations to 8-12% (TG enzyme solution), 2-3% (sodium alginate solution), and 1-2% (pectin solution), respectively.

[0057] Next, prepare a TGase-sodium alginate mixture. Accurately measure equal volumes of TGase solution and sodium alginate solution using a graduated cylinder and pour them into a conical flask. Stir the solutions in the conical flask using a stirrer to thoroughly mix the two solutions to form a TGase-sodium alginate mixture.

[0058] Finally, prepare the multifunctional polysaccharide microcapsules. Pour the TG enzyme-sodium alginate mixture into an emulsifier or high-pressure homogenizer. Slowly add the pectin solution while stirring at 1000-2000 rpm to form an oil-in-water emulsion. Transfer the emulsion to a container containing a 2-3% calcium chloride solution and let it sit at room temperature for 20-30 minutes to allow ionic crosslinking between the sodium alginate and calcium chloride, forming gel microcapsules. Filter the microcapsules through a mesh to remove excess calcium chloride solution. Dry the microcapsules in an oven set at 40-60°C to obtain the TG enzyme microcapsules.

[0059] Technical Effect: The functional polysaccharide microcapsules prepared in this way possess specific structures and properties. Their relatively uniform particle size and structure, when used as carriers for bacterial immobilization, provide a stable attachment environment for the composite bacterial strains, thereby enhancing their metabolic activity. This, in turn, has a positive impact on the subsequent fermentation process, contributing to improved flavor and texture of the final dried tofu product.

[0060] In another technical solution, in step S1, a pulsed electric field is applied every 8 hours during the culture process. The conditions of the pulsed electric field are: frequency 5-20 Hz, field strength 3-7 V / cm, and duration 2 minutes to promote the metabolic activity of the bacteria and the production of secondary metabolites.

[0061] In the above technical solution, specifically, when determining the pulse electric field application time interval, the time control can use a controller with a timing function. This controller can be a timing relay commonly used in laboratories or a timing module of a programmable logic controller (PLC). They can accurately set the time interval to meet the demand of applying a pulse electric field every 8 hours. The timing controller is usually installed in the control circuit of the pulse electric field generating device and is connected to the pulse electric field generating device to achieve accurate control of the pulse electric field application time. The time setting of the controller can be set to an 8-hour time interval according to the experimental requirements through its operation interface.

[0062] To achieve the pulsed electric field parameters, the frequency and field strength can be adjusted using a dedicated pulsed electric field generator. This generator is capable of generating pulsed electric fields of different frequencies and field strengths. Pulsed electric field generators that can cover a frequency range of 5-20Hz and a field strength range of 3-7V / cm are available on the market. The control of a 2-minute duration is also integrated into the function of this generator. During the experiment, a container containing the fermentation liquid of the composite bacteria is placed between the electrodes of the pulsed electric field generator to ensure that the fermentation liquid can fully receive the effect of the pulsed electric field. The frequency, field strength, and duration parameters of the pulsed electric field generator can be set based on experimental experience and the results of previous exploratory experiments to achieve the best effect in promoting bacterial metabolism.

[0063] The purpose of applying the pulsed electric field is to promote the metabolic activity of the composite bacteria and the production of secondary metabolites. The composite bacteria, glucose and other raw materials used can be purchased from regular microbial culture collection centers and chemical reagent suppliers.

[0064] In this technical solution, during step S1 of flavored dried tofu preparation, after the composite bacteria are introduced into sterilized yellow slurry containing glucose and functional polysaccharide microcapsules, the culture container is placed in the culture environment. At this point, a controller with a timing function is activated, and its interval is set to 8 hours. Simultaneously, a pulsed electric field generator is prepared. According to the experimental parameters, the frequency is adjusted to a value between 5 and 20 Hz, the field intensity is adjusted to a value between 3 and 7 V / cm, and the duration is set to 2 minutes. When the incubation time reaches 8 hours, the timing controller triggers the pulsed electric field generator. The pulsed electric field generator generates a pulsed electric field that meets the set parameters, which acts on the composite bacteria fermentation liquid in the culture container through electrodes. During the 2-minute application of the pulsed electric field, the composite bacteria in the fermentation liquid are stimulated by the electric field. After the 2-minute period, the pulsed electric field generator stops, and the composite bacteria culture continues. Thereafter, the timing controller triggers the pulsed electric field generator every 8 hours, repeating the above process until the composite bacteria culture has completed 24 hours. Throughout the entire cultivation process, this method of applying pulsed electric fields with specific parameters at regular intervals is expected to promote the metabolic activity of the composite bacterial strain and the production of secondary metabolites. After the cultivation is completed, the subsequent steps are followed to process the fermentation liquid, obtain a coagulant, and prepare dried tofu.

[0065] Technical effect: By applying a pulsed electric field with specific parameters every 8 hours during the culture of the composite bacteria, a positive effect can be exerted on the metabolism of the composite bacteria. This effect helps to improve the metabolic activity of the bacteria, enabling the bacteria to more efficiently utilize the nutrients in the culture medium for growth and metabolic activities. At the same time, it promotes the production of secondary metabolites, which may participate in the formation of flavor substances in dried tofu, thereby improving the flavor of the dried tofu. In terms of the nutrition of dried tofu, secondary metabolites may have certain nutritional value, or be able to interact with other ingredients in the dried tofu to enhance the overall nutritional quality of the dried tofu. Ultimately, the prepared dried tofu is optimized in both flavor and nutritional value.

[0066] In another technical solution, the application of the pulsed electric field is carried out in three stages, as follows: in the 0-8h stage, a pulsed electric field with a frequency of 5Hz and a field strength of 3V / cm is applied for a duration of 2min; in the 8-16h stage, a pulsed electric field with a frequency of 10Hz and a field strength of 5V / cm is applied for a duration of 2min; in the 16-24h stage, a pulsed electric field with a frequency of 20Hz and a field strength of 7V / cm is applied for a duration of 2min.

[0067] The above technical solution can be divided into three parts: The pulsed electric field is applied in stages: During the S1 culture process for preparing flavored dried tofu, the pulsed electric field is applied in three stages. The pulsed electric field parameters for each stage are: initial stage (0-8 hours), frequency 5Hz, field strength 3V / cm, duration 2 minutes; mid-stage (8-16 hours), frequency 10Hz, field strength 5V / cm, duration 2 minutes; late stage (16-24 hours), frequency 20Hz, field strength 7V / cm, duration 2 minutes.

[0068] The technical effect of this solution is that by applying pulsed electric fields with different parameters in stages, the metabolic processes of the composite bacterial strain at different growth stages are more precisely controlled. In the early stages, pulsed electric fields with lower frequencies and field intensities can gently stimulate the bacteria, allowing them to gradually adapt to the environment and initiate metabolic activity. Appropriately enhanced parameters in the middle stages further promote the metabolic activity of the bacteria and increase the production of metabolites. Higher frequencies and field intensities in the later stages of growth maintain metabolic activity and ensure the continuous and uniform production of secondary metabolites. These secondary metabolites participate in the formation of flavor substances in the dried tofu, enhancing its flavor. Furthermore, the uniformly generated secondary metabolites may better interact with other components in the dried tofu, optimizing its internal structure, thereby improving its overall quality and enhancing its taste and texture.

[0069] In another technical solution, step S1 is specifically as follows:

[0070] The method comprises the following steps: filtering yellow pulp water through a 200-mesh sieve, adding 0.5-1.2% whey protein powder and 0.3% yeast extract as nutritional supplements, sterilizing the water at 121° C. for 20 minutes, and cooling the water to 30° C.; inoculating Lactobacillus plantarum, Saccharomyces cerevisiae, and Lactobacillus brevis at a bacterial count ratio of 5:5:2, with a total inoculation amount of 8-12%, and adding 0.1% functional polysaccharide microcapsules as bacterial immobilization carriers; culturing the water at 28-32° C. and a pH value of 6.0-6.5 for 24 hours to obtain the fermentation liquid; and centrifuging the fermentation liquid at 3000 rpm for 10 minutes to obtain a coagulant for standby use.

[0071] In the above technical solution, during the pretreatment of the yellow slurry and the addition of nutritional supplements, the yellow slurry is filtered through a 200-mesh sieve. A common 200-mesh stainless steel sieve can be used, as it effectively filters out larger impurities such as bean dregs. After filtering, 0.5-1.2% whey protein powder and 0.3% yeast extract are added to the filtered yellow slurry as nutritional supplements. Whey protein powder and yeast extract are commercially available. Sterilization is performed at 121°C for 20 minutes in a standard high-pressure steam autoclave. Before sterilization, the yellow slurry with added nutritional supplements is placed in a suitable container and placed in the autoclave. The temperature and time are set, and after sterilization is complete, the slurry is naturally cooled to 30°C. The temperature and time are set to effectively kill bacteria in the yellow slurry while minimizing damage to the nutrients. This parameter combination was determined through consulting relevant materials and conducting multiple tests.

[0072] In terms of composite bacterial inoculation and fermentation condition setting, Lactobacillus plantarum, Saccharomyces cerevisiae, and Lactobacillus brevis are inoculated at a bacterial count ratio of 5:5:2, and 0.1% functional polysaccharide microcapsules are added as bacterial strain immobilization carriers. These bacterial strains can be purchased from professional microbial strain collection centers. Functional polysaccharide microcapsules are prepared according to the method described above. After inoculation, the coagulant is obtained by incubating at 28-32°C and a pH of 6.0-6.5 for 24 hours. A constant temperature incubator can be selected as the culture equipment. The inoculated yellow slurry water is placed in the incubator, and the appropriate culture temperature and pH value are maintained by adjusting the temperature and humidity control devices of the incubator.

[0073] Through the aforementioned fermentation process, the bacteria, under the influence of nutritional supplements, fully grow and metabolize, producing a variety of enzymes that work together to form a coagulant. In practice, after fermentation, the fermented liquid can be directly used to coagulate the soy milk in the subsequent dried tofu production process. This series of operations, combined with the addition of whey protein powder and yeast extract as nutritional supplements, provides the bacteria with a rich supply of nutrients, significantly increasing their growth rate and metabolic activity, thereby enhancing the performance of the coagulant and contributing to the subsequent production of higher-quality, flavored dried tofu, giving it a superior taste and texture.

[0074] In another technical solution, in step S2, the coagulant is added to the soy milk, stirred evenly, and placed in a water bath at 80° C. for 30 minutes to obtain tofu pudding, which is then poured into a tofu mold and pressed with a weight to shape the tofu. The specific steps of pouring the tofu pudding into the tofu mold and then pressing with a weight to shape the tofu include:

[0075] First, the solidified tofu is evenly spread into a tofu mold. Food-grade silicone mats are pre-placed on the bottom and side walls of the mold to prevent sticking and ensure a smooth surface. The tofu is then covered with a food-grade breathable membrane made from a composite of polylactic acid (PLA) and nano-silicon dioxide, with a pore size of 10 to 50 μm, which evenly distributes pressure and drains excess moisture. A pressing plate is placed above the membrane, with evenly distributed micro-protrusions 0.5 to 1 mm high and 5 to 10 mm apart to promote uniform drainage of moisture from the tofu. A weight is applied to the pressing plate to press the tofu. The pressure is adjusted in stages: 0.2 MPa for 10 minutes in the initial stage, 0.35 MPa for 20 minutes in the middle stage, and 0.5 MPa for 10 minutes in the final stage, gradually draining moisture and forming a dense three-dimensional network structure. After the pressing is completed, the weight and the breathable film are removed, the formed dried tofu is taken out of the mold, and placed in a ventilated environment to naturally cool to room temperature, thereby obtaining flavored dried tofu with a good three-dimensional network structure.

[0076] The above technical solution includes four steps: first, preparing the mold for the tofu; second, covering it with a breathable film; third, setting up the pressing plate and applying a weight; and fourth, shaping the tofu. During the mold preparation stage, the solidified tofu is evenly spread into the mold. Food-grade silicone mats are pre-placed on the bottom and sides of the mold. These mats can be made from commonly available, food-safe silicone materials, offering excellent flexibility and anti-stick properties. The mold can be made from common plastic or metal materials, available in a variety of sizes. In practice, the solidified tofu is first evenly laid on the bottom and sides of the mold, ensuring no wrinkles or gaps. Then, the solidified tofu is carefully poured into the mold, ensuring that it is evenly distributed, preparing for subsequent shaping. These materials are readily available commercially. The silicone mats primarily prevent the tofu from sticking to the mold and ensure a smooth surface.

[0077] During the breathable film covering stage, the surface of the dried tofu is covered with a food-grade breathable film. This film is made from a composite of polylactic acid (PLA) and nano-silica, with a pore size of 10-50μm. This breathable film can be purchased from some professional food packaging material suppliers. Its main function is to evenly distribute pressure and drain excess moisture. During operation, the breathable film is cut to the appropriate size and evenly covered on the surface of the dried tofu, ensuring complete coverage and a tight fit. Polylactic acid (PLA) is a biodegradable and environmentally friendly material, while nano-silica enhances the mechanical and breathability of the breathable film. The composite breathable film effectively meets the requirements of the dried tofu pressing process.

[0078] Regarding the press plate setup and weight pressing, a press plate is placed above the breathable membrane. Its surface features evenly distributed micro-protrusions with a height of 0.5-1mm and a spacing of 5-10mm. A weight is applied to the press plate to compress the dried tofu. Pressure is adjusted in stages: 0.2MPa for 10 minutes in the initial stage, 0.35MPa for 20 minutes in the middle stage, and 0.5MPa for 10 minutes in the final stage. The press plate can be made of metal or rigid plastic, with the micro-protrusions machined to the desired surface. Standard weights or other weights can be used as weights. In practice, the press plate is placed firmly on the breathable membrane to ensure that the protrusions effectively engage the membrane and the dried tofu. Then, according to the set pressure and time, the weight is gradually increased and the pressure is adjusted in stages to ensure uniform moisture release from the dried tofu, forming a dense three-dimensional network structure. Pressure is set by adding or removing weights, and the time is controlled by a timer.

[0079] Finally, the tofu is shaped. After pressing, remove the weights and breathable film, remove the formed tofu from the mold, and place it in a well-ventilated environment to naturally cool to room temperature. This can be a well-ventilated indoor space, or you can use a fume hood or other ventilation equipment to assist with ventilation. During this operation, carefully remove the weights and breathable film to avoid damaging the tofu. Then, remove the tofu completely from the mold and place it in a well-ventilated area to cool naturally. This process further solidifies the tofu, maintaining its shape and taste.

[0080] Through the above steps, the pressure distribution and moisture discharge method during the pressing process are optimized, ensuring that the moisture inside the dried tofu is evenly discharged, thereby forming a denser and more uniform three-dimensional network structure, avoiding problems such as surface cracks of the dried tofu that may be caused by traditional pressing methods, and improving the quality of the dried tofu.

[0081] In another technical solution, in step S2, soybeans are weighed and washed, and the water temperature is controlled at 25±2°C during washing, and 20kHz ultrasonic treatment is applied for 30 seconds between each washing; the washed soybeans are soaked in soft water containing 0.05mol / L sodium bicarbonate at a ratio of 1:3w / v, and intermittently soaked at 50r / min in a constant temperature oscillator at 25°C for 12 hours; the soaked soybeans are washed and crushed in two stages in a wall-breaking pulper preheated at 45°C: the first stage is coarse grinding at 8000rpm for 60 seconds, and the second stage is fine grinding at 12000rpm for 180 seconds. During the grinding, 60°C water is added three times in a gradient ratio of 1:6w / v; the obtained slurry is filtered through 200-mesh nylon cloth with centrifugal assistance, and the centrifugal conditions are: 3000rpm, 5min, and the filtrate is collected to obtain the residue-free soy milk. The residue-free soy milk is boiled in a step-by-step manner to inactivate the enzyme, and then terminally filtered through a three-layer composite filter membrane for standby use.

[0082] In the above technical solution, during the soybean cleaning process, the water temperature is controlled at 25±2°C, and 20kHz ultrasonic treatment is applied for 30 seconds between cleanings. The water temperature is chosen to ensure effective cleaning without affecting soybean quality due to excessively high or low temperatures. Around 25°C, close to room temperature, is more suitable for soybeans. The ultrasonic frequency is chosen to be 20kHz because it is currently known to be effective in disrupting soybean cell wall structure, promoting protein dissolution, and breaking down trypsin inhibitors. The cleaning equipment can be a common commercially available ultrasonic cleaning machine. The process involves placing the soybeans into the machine, adding an appropriate amount of clean water, and setting the water temperature and ultrasonic treatment time. Once the machine is started, the ultrasonic generator generates high-frequency vibrations, causing water molecules to cavitate, impacting the surface and interior of the soybeans, achieving the purpose of cleaning and auxiliary treatment. The raw soybeans can be selected from common, high-quality soybean varieties available on the market, which are widely available.

[0083] During the soaking step, the washed soybeans are soaked in soft water containing 0.05 mol / L sodium bicarbonate at a 1:3 w / v ratio. The soaking process is performed intermittently in a 25°C constant-temperature shaker at 50 rpm for 12 hours. The 1:3 soaking ratio was determined through experimentation to ensure sufficient water absorption and expansion of the soybeans while ensuring the appropriate concentration of the subsequent soymilk. A sodium bicarbonate concentration of 0.05 mol / L helps soften the soybeans and improve protein extraction. A standard laboratory constant-temperature shaker can be used. The container containing the soybeans and the soaking solution is placed on the shaker's tray. The temperature, speed, and intermittent time are set. The shaker's motor drives the tray to rotate at a constant speed, ensuring uniform heating and agitation of the soybeans in the soaking solution, enhancing the soaking effect. Soft water can be prepared using ion exchange resin softening, or commercially available soft water can be purchased.

[0084] When processing soybean slurry and soy milk, the soaked soybeans are washed and then crushed in two stages in a wall-breaking grinder preheated at 45°C. The first stage is coarse grinding at 8000rpm for 60 seconds, and the second stage is fine grinding at 12000rpm for 180 seconds. When grinding, 60°C water is added at a ratio of 1:18w / v. The resulting slurry is filtered through a 200-mesh nylon cloth with centrifugal assistance. The centrifugal conditions are: 3000rpm, 5min. The filtrate is collected to obtain residue-free soy milk. The residue-free soy milk is boiled and enzyme-killed in a step-by-step manner, and then terminally filtered through a three-layer composite filter membrane for standby use. The wall-breaking grinder can be a common household or commercial wall-breaking machine. It is first preheated to 45°C, and after the soybeans are put in, they are crushed according to the set coarse grinding and fine grinding parameters. This helps to dissolve the protein and reduce the effect of the heat generated during the grinding process on the protein. During filtration, 200-mesh nylon cloth can effectively filter out larger particles of impurities. Centrifugal-assisted filtration can further reduce soy milk turbidity. A standard laboratory centrifuge can be used. Place the centrifuge tubes containing the slurry symmetrically inside the centrifuge, set the speed and time, and centrifuge. Soy milk enzyme inactivation uses a stepped heating method, with three stages: heating to 70°C for 5 minutes with stirring, then heating to 85°C over 5 minutes and holding for 3 minutes, and finally heating to 100°C and holding for 5 minutes. This effectively inactivates lipoxygenase while retaining most of the natural globulin conformation. A three-layer composite filter membrane can be selected, consisting of an 80-mesh stainless steel screen, food-grade filter cloth (pore size 50μm), and ordinary coffee filter paper, to remove fine impurities from soy milk and improve its purity and quality.

[0085] The above series of treatments effectively disrupts the soybean cell wall structure, increases protein dissolution, decomposes trypsin inhibitors, and improves the digestibility and absorption of dried tofu. Furthermore, optimized grinding, filtration, and soymilk processing minimizes protein thermal denaturation and reduces soymilk turbidity, ensuring a smooth, grain-free texture. This paves the way for the subsequent formation of a favorable dried tofu gel network structure, ultimately enhancing its quality.

[0086] In another technical solution, the specific process of the step-by-step temperature increase and terminal filtration includes the following steps: pouring the residue-free soy milk into a heating device, heating and inactivating the enzymes in three stages: heating to 70°C and holding for 5 minutes with stirring, then heating to 85°C within 5 minutes and holding for 3 minutes, and finally heating to 100°C and holding for 5 minutes to obtain the enzyme-inactivated soy milk; filtering the enzyme-inactivated soy milk while hot with a three-layer filter, the first layer being an 80-mesh stainless steel screen, the second layer being a food-grade filter cloth with a pore size of 50 μm, and the third layer being ordinary coffee filter paper; and cooling the filtered soy milk to 80°C for use.

[0087] In the above technical solution, during the step-by-step heating and enzyme inactivation process, the residue-free soymilk is poured into a heating device and heated in three stages for enzyme inactivation. In the first stage, the soymilk is heated to 70°C and held for 5 minutes while stirring. This temperature and time setting ensures an initial temperature increase without excessive protein denaturation due to high temperatures. Stirring ensures more even heating of the soymilk. In the second stage, the temperature is raised to 85°C over 5 minutes and held for 3 minutes, further increasing the temperature and enhancing the enzyme inactivation effect. In the third stage, the temperature is raised to 100°C and held for 5 minutes to completely inactivate lipoxygenase. A standard electric heating pot can be used as the heating device, which offers uniform heating and controllable temperature. The residue-free soymilk is poured into the pot, and the heating power and time are adjusted to achieve a step-by-step heating process. A thermometer is used to monitor the temperature during the heating process to ensure compliance with the set heating curve.

[0088] After enzyme inactivation, soy milk is filtered while hot using a three-layer filter. The first layer is an 80-mesh stainless steel screen, which can filter out larger particles of impurities; the second layer is a food-grade filter cloth with a pore size of 50μm, which can further remove fine particles; the third layer is ordinary coffee filter paper, which is used to intercept even smaller impurities and improve the purity of the soy milk. In practice, the three layers of filter can be stacked in sequence and placed on a funnel. The enzyme-inactivated soy milk is then slowly poured into the filter for filtration. Stainless steel screens, food-grade filter cloths, and coffee filter paper are all commercially available at relatively affordable prices.

[0089] After filtering, the soy milk needs to be cooled to 80°C before use. This cooling process can be done naturally at room temperature, or in a water bath. Place the container of soy milk in a larger container of cold water to accelerate cooling through heat transfer. During the cooling process, a thermometer should be used to monitor the temperature of the soy milk. Cooling should be stopped when it reaches 80°C. This temperature is ideal for adding coagulants to produce dried tofu, ensuring a coagulated and high-quality product.

[0090] The aforementioned step-by-step temperature inactivation and terminal filtration process effectively inactivates lipoxygenase in soymilk while preserving much of the natural globulin conformation. This improves the strength of the subsequent dried tofu gel and enhances the uniformity of the three-dimensional pore structure. Using a common filter not only reduces costs but also effectively reduces soymilk turbidity and residual dregs, while also increasing filtration speed, making it suitable for small- to medium-scale dried tofu production.

[0091] <Example 1>

[0092] The present invention provides a method for preparing flavored dried tofu with a good three-dimensional network structure, which is specifically as follows:

[0093] S1, take yellow slurry and filter to remove bean dregs, add 3% glucose as a carbon source (3% refers to the mass ratio of glucose to yellow slurry is 3:100, the same below), and cool to room temperature after high temperature sterilization at 121 ° C for 20 min; inoculate the composite bacteria into the sterilized yellow slurry, and add 0.1% functional polysaccharide microcapsules as bacteria immobilization carriers (0.1% refers to the mass ratio of functional polysaccharide microcapsules to yellow slurry is 0.1:100, the same below), and cultivate at 28 ° C, pH 6.0 for 24 h to obtain a fermentation liquid. After the cultivation is completed, the fermentation liquid is placed at 3000 rpm and centrifuged for 10 min to remove the thalline to obtain a coagulant, which is stand-by; wherein the inoculum size of the composite bacteria is 8%, and the composite bacteria includes plant lactobacillus and saccharomyces cerevisiae with a bacterial count ratio of 1:1;

[0094] The functional polysaccharide microcapsules are prepared as follows:

[0095] Dissolve TG enzyme in water to form a TG enzyme solution with a mass concentration of 8%; dissolve sodium alginate and pectin in water to form a sodium alginate solution with a mass concentration of 2% and a pectin solution with a mass concentration of 1%; dissolve calcium chloride in water to form a calcium chloride solution with a mass concentration of 2%;

[0096] The TG enzyme solution and the sodium alginate solution are mixed, and the TG enzyme-sodium alginate mixture is poured into an emulsifier. Under the condition of a stirring speed of 1000 rpm, the pectin solution is slowly added to form an oil-in-water emulsion; the oil-in-water emulsion is transferred to a container added with a calcium chloride solution, and allowed to stand at room temperature for 20 minutes to allow the sodium alginate and the calcium chloride to undergo ion crosslinking to form gel microcapsules; the microcapsules are filtered through a sieve to remove excess calcium chloride solution to obtain the functional polysaccharide microcapsules; wherein the volume ratio of the TG enzyme solution, the sodium alginate solution, the pectin solution, and the calcium chloride solution is 1:1:0.5:5.

[0097] S2. Accurately weigh a certain amount of soybeans, wash them with clean water, and soak them at room temperature for 12 hours to allow them to fully absorb water and swell. Rinse the soaked soybeans twice with water, grind them in a soymilk maker for 5 minutes, and filter them through nylon cloth to obtain residue-free soymilk. Boil the soymilk for 5 minutes and filter it again for later use. After the soymilk cools to about 80° C., add the coagulant to the soymilk, stir evenly, place it in an 80° C. water bath, and let it stand for 30 minutes. Pour it into a dried tofu mold and press it with a weight to shape the dried tofu. The volume ratio of the coagulant to the soymilk is 1:3.

[0098] The specific steps of pressing the dried tofu with a heavy object to form the dried tofu are as follows:

[0099] In steps A1 and S2, the coagulant is added to the soy milk, stirred evenly, and placed in an 80° C. water bath for 30 minutes to obtain solidified tofu pudding; the solidified tofu pudding is evenly spread into a dried tofu mold, and a food-grade silicone mat is pre-laid on the bottom and side walls of the mold to prevent adhesion and ensure a smooth surface of the dried tofu;

[0100] A2. Cover the surface of the soybean curd with a layer of food-grade breathable film;

[0101] A3. Place a pressing plate on top of the breathable membrane. The surface of the pressing plate is equipped with evenly distributed micro-protrusions with a height of 1 mm and a spacing of 10 mm to promote the uniform discharge of moisture from the dried tofu.

[0102] A4. Apply a heavy object on the pressing plate to press. Adjust the pressure in stages during the pressing process. The initial pressure is 0.2 MPa for 10 minutes, the middle pressure is 0.35 MPa for 20 minutes, and the final pressure is 0.5 MPa for 10 minutes to gradually expel moisture and form a dense three-dimensional network structure.

[0103] A5. After the pressing is completed, remove the weight and breathable film, take the formed dried tofu out of the mold, and place it in a ventilated environment to naturally cool to room temperature to obtain flavored dried tofu with a good three-dimensional network structure.

[0104] <Example 2>

[0105] S1. Filter yellow pulp water to remove bean dregs, add 3% glucose as a carbon source, sterilize at 121° C. for 20 min, and then cool to room temperature; inoculate the composite bacteria into the sterilized yellow pulp water, add 0.1% functional polysaccharide microcapsules as a bacterial immobilization carrier, and culture at 32° C. and a pH of 6.5 for 24 h to obtain a fermentation broth. After the culture is completed, centrifuge the fermentation broth at 3000 rpm for 10 min to remove the bacteria, obtain a coagulant, and use it for later use; wherein the inoculation amount of the composite bacteria is 10%, and the composite bacteria include Lactobacillus plantarum and Saccharomyces cerevisiae at a bacterial count ratio of 1:1;

[0106] The functional polysaccharide microcapsules are prepared as follows:

[0107] Dissolving TG enzyme in water to form a TG enzyme solution with a mass concentration of 10%; dissolving sodium alginate and pectin in water to form a sodium alginate solution with a mass concentration of 3% and a pectin solution with a mass concentration of 2%; dissolving calcium chloride in water to form a calcium chloride solution with a mass concentration of 3%;

[0108] The TG enzyme solution and the sodium alginate solution are mixed, and the TG enzyme-sodium alginate mixture is poured into an emulsifier. Under the condition of a stirring speed of 2000 rpm, the pectin solution is slowly added to form an oil-in-water emulsion; the oil-in-water emulsion is transferred to a container containing a calcium chloride solution and allowed to stand at room temperature for 30 minutes to allow the sodium alginate and the calcium chloride to undergo ion crosslinking to form gel microcapsules; the microcapsules are filtered through a sieve to remove excess calcium chloride solution to obtain the functional polysaccharide microcapsules; wherein the volume ratio of the TG enzyme solution, the sodium alginate solution, the pectin solution, and the calcium chloride solution is 1:1:0.5:5.

[0109] S2. Accurately weigh a certain amount of soybeans, wash them with clean water, and soak them at room temperature for 12 hours to allow them to fully absorb water and swell. Rinse the soaked soybeans twice with water, grind them in a soymilk maker for 5 minutes, and filter them through nylon cloth to obtain residue-free soymilk. Boil the soymilk for 5 minutes and filter it again for later use. After the soymilk cools to about 80° C., add the coagulant to the soymilk, stir evenly, place it in an 80° C. water bath, and let it stand for 30 minutes. Pour it into a dried tofu mold and press it with a weight to shape the dried tofu. The volume ratio of the coagulant to the soymilk is 1:5.

[0110] The specific steps of pressing the dried tofu with a heavy object to form the dried tofu are as follows:

[0111] In steps A1 and S2, the coagulant is added to the soy milk, stirred evenly, and placed in an 80° C. water bath for 30 minutes to obtain solidified tofu pudding; the solidified tofu pudding is evenly spread into a dried tofu mold, and a food-grade silicone mat is pre-laid on the bottom and side walls of the mold to prevent adhesion and ensure a smooth surface of the dried tofu;

[0112] A2. Cover the surface of the soybean curd with a layer of food-grade breathable film;

[0113] A3. Place a pressing plate on top of the breathable membrane. The surface of the pressing plate is equipped with evenly distributed micro-protrusions with a height of 1 mm and a spacing of 10 mm to promote the uniform discharge of moisture from the dried tofu.

[0114] A4. Apply a heavy object on the pressing plate to press. Adjust the pressure in stages during the pressing process. The initial pressure is 0.2 MPa for 10 minutes, the middle pressure is 0.35 MPa for 20 minutes, and the final pressure is 0.5 MPa for 10 minutes to gradually expel moisture and form a dense three-dimensional network structure.

[0115] A5. After the pressing is completed, remove the weight and breathable film, take the formed dried tofu out of the mold, and place it in a ventilated environment to naturally cool to room temperature to obtain flavored dried tofu with a good three-dimensional network structure.

[0116] <Example 3>

[0117] The present invention provides a method for preparing flavored dried tofu with a good three-dimensional network structure, which is specifically as follows:

[0118] S1, take yellow pulp water, filter it to remove bean dregs, add 3% glucose as a carbon source, sterilize it at 121 ° C for 20 minutes, and then cool it to room temperature; inoculate the composite bacteria into the sterilized yellow pulp water, and add 0.1% functional polysaccharide microcapsules as bacteria immobilization carriers, and culture it at 28 ° C and pH 6.0 for 24 hours to obtain a fermentation liquid. After the culture is completed, the fermentation liquid is placed at 3000 rpm and centrifuged for 10 minutes to remove the bacteria to obtain a coagulant for standby use; wherein the inoculation amount of the composite bacteria is 8%, and the composite bacteria is 0.1%. The combined bacteria include Lactobacillus plantarum and Saccharomyces cerevisiae with a bacterial count ratio of 1:1; a pulsed electric field is applied every 8 hours during the culture process. In the 0-8 hour stage, a pulsed electric field with a frequency of 5 Hz and a field strength of 3 V / cm is applied for a duration of 2 minutes; in the 8-16 hour stage, a pulsed electric field with a frequency of 10 Hz and a field strength of 5 V / cm is applied for a duration of 2 minutes; in the 16-24 hour stage, a pulsed electric field with a frequency of 20 Hz and a field strength of 7 V / cm is applied for a duration of 2 minutes to promote the metabolic activity of the bacteria and the production of secondary metabolites.

[0119] The functional polysaccharide microcapsules are prepared as follows:

[0120] Dissolve TG enzyme in water to form a TG enzyme solution with a mass concentration of 8%; dissolve sodium alginate and pectin in water to form a sodium alginate solution with a mass concentration of 2% and a pectin solution with a mass concentration of 1%; dissolve calcium chloride in water to form a calcium chloride solution with a mass concentration of 2%;

[0121] The method comprises the following steps: mixing a TG enzyme solution with a sodium alginate solution, pouring the TG enzyme-sodium alginate mixture into an emulsifier or a high-pressure homogenizer, and slowly adding a pectin solution at a stirring speed of 1000 rpm to form an oil-in-water emulsion; transferring the oil-in-water emulsion into a container containing a calcium chloride solution, and standing the container at room temperature for 20 minutes to allow the sodium alginate and calcium chloride to undergo ionic crosslinking to form gel microcapsules; filtering the microcapsules using a sieve to remove excess calcium chloride solution to obtain the functional polysaccharide microcapsules; wherein the volume ratio of the TG enzyme solution, the sodium alginate solution, the pectin solution, and the calcium chloride solution is 1:1:0.5:5.

[0122] S2. Accurately weigh a certain amount of soybeans, wash them with clean water, and soak them at room temperature for 12 hours to allow them to fully absorb water and swell. Rinse the soaked soybeans twice with water, grind them in a soymilk maker for 5 minutes, and filter them through nylon cloth to obtain residue-free soymilk. Boil the soymilk for 5 minutes and filter it again for later use. After the soymilk cools to about 80° C., add the coagulant to the soymilk, stir evenly, place it in an 80° C. water bath, and let it stand for 30 minutes. Pour it into a dried tofu mold and press it with a weight to shape the dried tofu. The volume ratio of the coagulant to the soymilk is 1:3.

[0123] The specific steps of pressing the dried tofu with a heavy object to form the dried tofu are as follows:

[0124] In steps A1 and S2, the coagulant is added to the soy milk, stirred evenly, and placed in an 80° C. water bath for 30 minutes to obtain solidified tofu pudding; the solidified tofu pudding is evenly spread into a dried tofu mold, and a food-grade silicone mat is pre-laid on the bottom and side walls of the mold to prevent adhesion and ensure a smooth surface of the dried tofu;

[0125] A2. Cover the surface of the soybean curd with a layer of food-grade breathable film;

[0126] A3. Place a pressing plate on top of the breathable membrane. The surface of the pressing plate is equipped with evenly distributed micro-protrusions with a height of 1 mm and a spacing of 10 mm to promote the uniform discharge of moisture from the dried tofu.

[0127] A4. Apply a heavy object on the pressing plate to press. Adjust the pressure in stages during the pressing process. The initial pressure is 0.2 MPa for 10 minutes, the middle pressure is 0.35 MPa for 20 minutes, and the final pressure is 0.5 MPa for 10 minutes to gradually expel moisture and form a dense three-dimensional network structure.

[0128] A5. After the pressing is completed, remove the weight and breathable film, take the formed dried tofu out of the mold, and place it in a ventilated environment to naturally cool to room temperature to obtain flavored dried tofu with a good three-dimensional network structure.

[0129] <Example 4>

[0130] The present invention provides a method for preparing flavored dried tofu with a good three-dimensional network structure, which is specifically as follows:

[0131] S1, take yellow slurry and filter it through a 200-mesh sieve, add 1.0% whey protein powder and 0.3% yeast extract as nutritional supplements (1.0% means the mass ratio of whey protein powder to yellow slurry is 1:100, 0.3% means the mass ratio of yeast extract to yellow slurry is 0.3:100), sterilize at 121°C for 20 minutes and then cool to 30°C; inoculate the composite strain into the sterilized yellow slurry, add 0.1% functional polysaccharide microcapsules as strain immobilization carriers, and culture at 28°C and pH 6.0 for 24 hours to obtain the coagulant, which is ready for use; wherein the composite strain The inoculation amount of the composite bacteria is 8%, and the composite bacteria include plant lactobacillus, saccharomyces cerevisiae, and Lactobacillus brevis in a bacterial ratio of 5:5:2. During the culture process, a pulsed electric field is applied once every 8 hours. In the 0-8 hour stage, a pulsed electric field with a frequency of 5 Hz and a field strength of 3 V / cm is applied for a duration of 2 minutes; in the 8-16 hour stage, a pulsed electric field with a frequency of 10 Hz and a field strength of 5 V / cm is applied for a duration of 2 minutes; in the 16-24 hour stage, a pulsed electric field with a frequency of 20 Hz and a field strength of 7 V / cm is applied for a duration of 2 minutes to promote the metabolic activity of the bacteria and the generation of secondary metabolites.

[0132] The functional polysaccharide microcapsules are prepared as follows:

[0133] Dissolve TG enzyme in water to form a TG enzyme solution with a mass concentration of 8%; dissolve sodium alginate and pectin in water to form a sodium alginate solution with a mass concentration of 2% and a pectin solution with a mass concentration of 1%; dissolve calcium chloride in water to form a calcium chloride solution with a mass concentration of 2%;

[0134] The method comprises the following steps: mixing a TG enzyme solution with a sodium alginate solution, pouring the TG enzyme-sodium alginate mixture into an emulsifier or a high-pressure homogenizer, and slowly adding a pectin solution at a stirring speed of 1000 rpm to form an oil-in-water emulsion; transferring the oil-in-water emulsion into a container containing a calcium chloride solution, and standing the container at room temperature for 20 minutes to allow the sodium alginate and calcium chloride to undergo ionic crosslinking to form gel microcapsules; filtering the microcapsules using a sieve to remove excess calcium chloride solution to obtain the functional polysaccharide microcapsules; wherein the volume ratio of the TG enzyme solution, the sodium alginate solution, the pectin solution, and the calcium chloride solution is 1:1:0.5:5.

[0135] S2. Accurately weigh a certain amount of soybeans, wash them with clean water, and soak them at room temperature for 12 hours to allow them to fully absorb water and swell. Rinse the soaked soybeans twice with water, grind them in a soymilk maker for 5 minutes, and filter them through nylon cloth to obtain residue-free soymilk. Boil the soymilk for 5 minutes and filter it again for later use. After the soymilk cools to about 80° C., add the coagulant to the soymilk, stir evenly, place it in an 80° C. water bath, and let it stand for 30 minutes. Pour it into a dried tofu mold and press it with a weight to shape the dried tofu. The volume ratio of the coagulant to the soymilk is 1:3.

[0136] The specific steps of pressing the dried tofu with a heavy object to form the dried tofu are as follows:

[0137] In steps A1 and S2, the coagulant is added to the soy milk, stirred evenly, and placed in an 80° C. water bath for 30 minutes to obtain solidified tofu pudding; the solidified tofu pudding is evenly spread into a dried tofu mold, and a food-grade silicone mat is pre-laid on the bottom and side walls of the mold to prevent adhesion and ensure a smooth surface of the dried tofu;

[0138] A2. Cover the surface of the soybean curd with a layer of food-grade breathable film;

[0139] A3. Place a pressing plate on top of the breathable membrane. The surface of the pressing plate is equipped with evenly distributed micro-protrusions with a height of 1 mm and a spacing of 10 mm to promote the uniform discharge of moisture from the dried tofu.

[0140] A4. Apply a heavy object on the pressing plate to press. Adjust the pressure in stages during the pressing process. The initial pressure is 0.2 MPa for 10 minutes, the middle pressure is 0.35 MPa for 20 minutes, and the final pressure is 0.5 MPa for 10 minutes to gradually expel moisture and form a dense three-dimensional network structure.

[0141] A5. After the pressing is completed, remove the weight and breathable film, take the formed dried tofu out of the mold, and place it in a ventilated environment to naturally cool to room temperature to obtain flavored dried tofu with a good three-dimensional network structure.

[0142] Comparative Example 1

[0143] The difference from Example 1 is that the coagulant is magnesium chloride.

[0144] Comparative Example 2

[0145] The difference from Example 1 is that TG enzyme is not added, and the other aspects are the same as Example 1.

[0146] Comparative Example 3

[0147] The difference from Example 1 is that no pectin solution is added, and the other aspects are the same as Example 1.

[0148] <Determination of Changes in Protein Secondary Structure Content in Dried Tofu During Storage>

[0149] The dried tofu was vacuum packed and stored at 4°C.

[0150] Determination method:

[0151] The prepared dried bean curd samples were sampled and placed in a vacuum freeze dryer for freeze drying, and then ground into powder using a grinder for later use. The dried bean curd sample powder and dried potassium bromide solid powder were accurately weighed in a weight ratio of 1:50 and placed in an agate mortar for further grinding and mixing. The mixture was pressed into clear tablets using an infrared tablet press (10 MPa). The tablets were passed through an infrared spectrometer for structural analysis of the samples, with the wavelength range set to 500-4000 cm -1 , with a resolution of 4cm -1 , the number of scans is 24 times.

[0152] The protein secondary structure content of the dried tofu in Examples 1 to 4 and Comparative Examples 1 to 3 during storage was measured. The specific results are shown in Table 1.

[0153] Table 1 Determination results of protein secondary structure content in dried tofu during storage in Examples 1 to 4 and Comparative Examples 1 to 3

[0154]

[0155]

[0156] As can be seen in Table 1, the β-sheets of the dried tofu prepared in Examples 1-4 are not significantly different from those prepared in Comparative Examples 1-3, but the β-turns are significantly higher than those in Comparative Examples 1-3, indicating that the order of the secondary structure of the protein in the dried tofu prepared in the present invention is enhanced to a certain extent. Furthermore, the β-turns are connected by secondary bonds, resulting in a more stable protein gel network. Therefore, the dried tofu prepared in the present invention exhibits a more robust three-dimensional network structure.

[0157] <Determination of Texture Properties of Dried Tofu>

[0158] Measurement Method: Tofu texture was measured using a TA.XT.Plus texture analyzer (physical property tester) from Stable Microsystems, UK. A flat-surfaced piece of dried tofu (2 x 2 x 1 cm) was removed from the center using a knife. A P36R cylindrical flat-bottom probe was used, with a trigger force of 5g. Measurement speeds were 2.0 mm / s, 1.0 mm / s, and 1.0 mm / s before, during, and after the measurement, respectively. Each sample was measured three times, and the average value was calculated.

[0159] The dried tofu prepared in Examples 1 to 4 and Comparative Examples 1 to 3 were vacuum-packed and stored at 4° C. The elasticity and hardness of the dried tofu stored for 0 h in Examples 1 to 4 and Comparative Examples 1 to 3 were measured. Specific results are shown in Table 2.

[0160] Table 2 Test results of texture properties of dried tofu prepared in Examples 1 to 4 and Comparative Examples 1 to 3

[0161] Experimental example Hardness / g elasticity Example 1 1189.32 0.8242 Example 2 1213.34 0.8368 Example 3 1228.45 0.8562 Example 4 1235.65 0.8654 Comparative Example 1 834.72 0.6562 Comparative Example 2 1125.65 0.7684 Comparative Example 3 876.56 0.6658

[0162] As can be seen from Table 2, compared with Comparative Examples 1 to 3, the dried tofu prepared in Examples 1 to 4 of the present invention have a certain improvement in hardness and elasticity, indicating that the dried tofu prepared in the present invention has good texture properties.

[0163] In summary, the dried tofu prepared by the present invention has a good three-dimensional network structure and texture properties. This is because in the present invention: first, sodium alginate is used to encapsulate TG enzyme to prepare microcapsules, and then a pectin layer is wrapped on the prepared microcapsules to prepare multifunctional microcapsules. When the multifunctional microcapsules are put into fermentation yellow water, the multifunctional microcapsules can serve as bacterial carriers, provide active sites for the composite bacterial strains, and promote the growth and metabolism of the composite bacterial strains. At the same time, some beneficial components produced by the composite bacterial strains during metabolism can also be embedded in the multifunctional microcapsules, and the beneficial components are slowly released during the subsequent soy milk coagulation process to promote Soy milk coagulant, and due to the sustained-release characteristics of the multifunctional microcapsules, the soy milk can be evenly solidified, thereby improving the texture properties of dried tofu; in addition, the core of the multifunctional microcapsules is embedded with TG enzyme. When the soy milk begins to solidify, the outer pectin and sodium alginate layers minimize the possibility of TG inactivation at high temperatures. At the same time, the small molecule beneficial components produced by the metabolism of the composite bacteria embedded in the pectin are gradually released, promoting the coagulation of the soy milk. When the soy milk gradually cools down, the outer pectin and sodium alginate gradually dissolve, and the TG enzyme is gradually released, cross-linking with the protein in the soy milk to form dried tofu with a good three-dimensional network structure. In Comparative Example 3, since the sodium alginate was not coated with a pectin layer, the sodium alginate was partially decomposed during the fermentation process, indirectly leading to the partial release of TG enzyme. In Comparative Example 2, since TG enzyme was not used, there was no further cross-linking effect of TG enzyme during the gradual cooling of the soy milk, resulting in deterioration of the texture of the dried tofu. In Comparative Example 1, magnesium chloride was used to prepare the dried tofu, and the resulting dried tofu protein aggregates had large pores, resulting in poor texture.

[0164] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and embodiments shown and described herein.

Claims

1. A method for preparing flavored dried tofu with a good three-dimensional network structure, characterized in that: The following steps are involved: S1. Filter yellow pulp water to remove bean dregs, add 3% glucose as a carbon source, sterilize at 121° C. for 20 min, and then cool to room temperature; inoculate the composite bacteria into the sterilized yellow pulp water, add 0.1% functional polysaccharide microcapsules as a bacterial immobilization carrier, and culture at 28-32° C. and a pH value of 6.0-6.5 for 24 h to obtain a fermentation broth, centrifuge the fermentation broth at 3000 rpm for 10 min to obtain a coagulant for standby use; wherein the inoculation amount of the composite bacteria is 8-12%, and the composite bacteria include Lactobacillus plantarum and Saccharomyces cerevisiae at a bacterial count ratio of 1:1; the functional polysaccharide microcapsules are prepared from a TGase-sodium alginate mixture and a pectin solution; S2. Accurately weigh a certain amount of soybeans, wash them with clean water, and soak them at room temperature for 12 hours. Rinse the soaked soybeans twice with water, grind them in a soymilk maker for 5 minutes, and filter them through nylon cloth to obtain residue-free soymilk. Boil the soymilk for 5 minutes and filter it again for later use. After the soymilk is cooled to 80° C., add the coagulant to the soymilk, stir evenly, place it in an 80° C. water bath and let it stand for 30 minutes. Pour it into a dried tofu mold, and press it with a weight to shape the dried tofu. The volume ratio of the coagulant to the soymilk is 1:3-5.

2. The method for preparing flavored dried tofu with a good three-dimensional network structure according to claim 1, wherein: In step S1, the preparation of the functional polysaccharide microcapsules is specifically as follows: TG enzyme is mixed with water to form a TG enzyme solution with a mass concentration of 8-12%; sodium alginate and pectin are mixed with water respectively to form a sodium alginate solution with a mass concentration of 2%-3% and a pectin solution with a mass concentration of 1%-2%, respectively; the TG enzyme solution and the sodium alginate solution are mixed to obtain a TG enzyme-sodium alginate mixed solution, the TG enzyme-sodium alginate mixed solution is treated with the pectin solution to form a composite wall material, and the functional polysaccharide microcapsules are obtained after drying; wherein the volume ratio of the TG enzyme solution to the sodium alginate solution is 1:

1.

3. The method for preparing flavored dried tofu with a good three-dimensional network structure according to claim 2, wherein: The steps of treating the TG enzyme-sodium alginate mixture with the pectin solution to form a composite wall material, and drying to obtain the functional polysaccharide microcapsules are as follows: Calcium chloride is dissolved in water to form a calcium chloride solution with a mass concentration of 2% to 3%; a TG enzyme-sodium alginate mixture is poured into an emulsifier or a high-pressure homogenizer, and a pectin solution is slowly added under a stirring speed of 1000 rpm to 2000 rpm to form an oil-in-water emulsion; the oil-in-water emulsion is transferred to a container containing a calcium chloride solution, and the container is allowed to stand at room temperature for 20 to 30 minutes to form gel microcapsules, and the gel microcapsules are filtered through a sieve to obtain the functional polysaccharide microcapsules.

4. The method for preparing flavored dried tofu with a good three-dimensional network structure according to claim 3, wherein: In step S1, a pulsed electric field is applied every 8 hours during the culture process. The conditions of the pulsed electric field are: frequency 5-20 Hz, field strength 3-7 V / cm, and duration 2 minutes to promote the metabolic activity of the bacteria and the production of secondary metabolites.

5. The method for preparing flavored dried tofu with a good three-dimensional network structure according to claim 4, characterized in that: The application of the pulsed electric field is carried out in three stages, as follows: in the 0-8h stage, a pulsed electric field with a frequency of 5 Hz and a field strength of 3 V / cm is applied for 2 minutes; in the 8-16h stage, a pulsed electric field with a frequency of 10 Hz and a field strength of 5 V / cm is applied for 2 minutes; in the 16-24h stage, a pulsed electric field with a frequency of 20 Hz and a field strength of 7 V / cm is applied for 2 minutes.

6. The method for preparing high-protein flavored dried tofu with a good three-dimensional network structure according to claim 1, characterized in that: The S1 step is as follows: The method comprises the following steps: filtering yellow pulp water through a 200-mesh sieve, adding 0.5-1.2% whey protein powder and 0.3% yeast extract as nutritional supplements, sterilizing the water at 121° C. for 20 minutes, and cooling the water to 30° C.; inoculating Lactobacillus plantarum, Saccharomyces cerevisiae, and Lactobacillus brevis at a bacterial count ratio of 5:5:2, with a total inoculation amount of 8-12%, and adding 0.1% functional polysaccharide microcapsules as bacterial immobilization carriers; culturing the water at 28-32° C. and a pH value of 6.0-6.5 for 24 hours to obtain the fermentation liquid; and centrifuging the fermentation liquid at 3000 rpm for 10 minutes to obtain a coagulant for standby use.

7. The method for preparing flavored dried tofu with a good three-dimensional network structure according to claim 4, characterized in that: In step S2, the coagulant is added to the soy milk, stirred evenly, and placed in a water bath at 80° C. for 30 minutes to obtain tofu pudding, which is then poured into a tofu mold and pressed with a weight to form the tofu. The specific steps of pouring the tofu pudding into the tofu mold and then pressing with a weight to form the tofu include: A1. Evenly spread the tofu into a dried tofu mold. Pre-place food-grade silicone mats on the bottom and side walls of the mold. A2. Cover the surface of the soybean curd with a food-grade breathable film with a pore size of 10-50 μm; A3. Place a pressing plate on top of the breathable membrane. The surface of the pressing plate is provided with evenly distributed micro-protrusions with a height of 0.5 to 1 mm and a spacing of 5 to 10 mm to promote uniform drainage of moisture from the dried tofu. A4. Apply a heavy object on the pressing plate to press. Adjust the pressure in stages during the pressing process. The initial pressure is 0.2 MPa, which lasts for 10 minutes. The middle pressure is 0.35 MPa, which lasts for 20 minutes. The final pressure is 0.5 MPa, which lasts for 10 minutes. A5. After the pressing is completed, remove the weight and breathable film, take the formed dried tofu out of the mold, and place it in a ventilated environment to naturally cool to room temperature to obtain flavored dried tofu with a good three-dimensional network structure.

8. The method for preparing high-protein flavored dried tofu with a good three-dimensional network structure according to claim 1, characterized in that: In step S2, soybeans are weighed and washed, and the water temperature is controlled at 25±2°C during washing, and 20kHz ultrasonic treatment is applied for 30 seconds between each washing; the washed soybeans are soaked in soft water containing 0.05mol / L sodium bicarbonate at a ratio of 1:3w / v, and intermittently soaked at 50r / min in a constant temperature oscillator at 25°C for 12 hours; the soaked soybeans are washed and crushed in two stages in a wall-breaking pulper preheated at 45°C: the first stage is coarse grinding at 8000rpm for 60 seconds, and the second stage is fine grinding at 12000rpm for 180 seconds, and 60°C water is added during grinding at a ratio of 1:18w / v; the obtained slurry is filtered through 200-mesh nylon cloth with centrifugal assistance, and the centrifugal conditions are: 3000rpm, 5min, and the filtrate is collected to obtain the residue-free soy milk, and the residue-free soy milk is boiled and enzyme-inactivated in a step-by-step manner, and then terminally filtered through a three-layer composite filter membrane for standby use.

9. The method for preparing high-protein flavored dried tofu with a good three-dimensional network structure according to claim 8, characterized in that: The specific process of the step-by-step temperature increase and terminal filtration includes the following steps: pouring the residue-free soy milk into a heating device and heating and inactivating the enzymes in three stages: heating to 70°C and holding for 5 minutes with stirring, then heating to 85°C within 5 minutes and holding for 3 minutes, and finally heating to 100°C and holding for 5 minutes to obtain the enzyme-inactivated soy milk; filtering the enzyme-inactivated soy milk while hot through a three-layer filter, wherein the first layer is an 80-mesh stainless steel screen, the second layer is a food-grade filter cloth with a pore size of 50 μm, and the third layer is ordinary coffee filter paper; and the soy milk after filtration is cooled to 80°C for use.

10. Flavored dried tofu prepared by the method for preparing flavored dried tofu with a good three-dimensional network structure according to any one of claims 1 to 9.

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