Urease extraction-bean curd production combined preparation method

Abstract

The invention discloses a urease extraction-bean curd production combined preparation method, and relates to the technical field of engineering construction materials. In order to solve the problems that the existing urease extraction and purification cost is relatively high, the waste is relatively large in the bean curd production process, and the cost and pollution are not reduced by combining the urease extraction and purification cost and the bean curd production process, the following technical scheme is provided: grinding dry soybeans into fine powder, adding the fine powder into water, mixing, and adding a salt precipitator to separate out a urease solution and bean powder precipitate; stirring and filtering the bean powder precipitate to obtain raw soybean milk and bean dregs, boiling the soybean milk, marinating to prepare bean curd, and dehydrating and refining the bean dregs to prepare solid vegetable protein or biochar. Compared with a traditional mode, one-step urease liquid extraction is creatively added, the yield of bean products is not affected, the high-activity urease liquid is extracted, waste recycling is achieved, and the production cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of engineering construction materials, and in particular to a urease extraction-tofu production combined preparation method. Background Art

[0002] Urease, also known as urease, is an oligomeric enzyme, an enzyme that can catalyze the decomposition of urea into ammonia and carbon dioxide. It is widely found in organisms such as animals, bacteria and algae. In recent years, people have found that urease can be used to induce calcium carbonate precipitation reinforcement soil (EICP). This technology is mainly based on the direct catalysis of urea hydrolysis by urease to produce carbonate ions that combine with calcium ions in the environment to precipitate calcium carbonate crystals with cementing effects, thereby playing a role in solidification. It is a new type of environmentally friendly treatment technology with high efficiency, greenness and low cost, and has attracted more and more attention. However, in the EICP reinforcement process, urease consumption is large. At present, the extraction of urease mainly depends on extraction and purification from legumes through a series of biochemical methods, which is costly. For example, Cui Youhong et al. proposed in "Study on the Extraction and Properties of Soybean Urease" that soybeans should be crushed into soybean powder, then acetate buffer should be added to extract the liquid, the supernatant should be collected and sodium sulfite should be added to salt out, and finally DEAE-cellulose ion exchange chromatography should be used to make urease. The process is cumbersome and the steps are complicated, resulting in a high price.

[0003] The traditional tofu production process is to soak soybeans for 6-12 hours, discard the soaking wastewater, grind into soy milk, filter to remove the dregs, get pure raw soy milk, boil over low heat to get cooked soy milk and bean skin, add brine to form tofu pudding, further press to drain the yellow pulp water, and finally make tofu. The traditional tofu production process produces a large number of by-products (such as dregs, soaking wastewater, and yellow pulp water), and the waste caused by discarding them is also quite huge. Summary of the invention

[0004] The purpose of the present invention is to provide a urease extraction-tofu production combined preparation method to solve the problems that the existing urease extraction and purification costs are high, the tofu production process is wasteful, and there is a lack of combining the two to reduce costs and pollution.

[0005] The technical solution of the present invention to solve the above technical problems is as follows: A urease extraction-tofu production combined preparation method comprises the following steps: S1: crushing and grinding dry soybeans into fine bean powder, and storing the ground fine bean powder; S2: adding the ground fine bean powder into water, stirring thoroughly until uniformly mixed, adding a salt precipitant into the mixture for precipitation treatment, filtering for the first time to separate the bean powder precipitate at the lower layer and the urease solution at the upper layer, extracting and storing the urease solution; S3: adding the bean powder precipitate obtained by the first filtration back into the water for a second stirring to form a slurry, and then performing a second filtration to separate the raw soy milk and the bean dregs, and repeating the second filtration process at least once to ensure sufficient separation; S4: heating and boiling the obtained raw soybean milk to convert it into cooked soybean milk, stirring and slowly adding brine to brine until the soybean milk solidifies into flocculent tofu blanks, transferring the flocculent tofu blanks into a tofu box covered with gauze, applying pressure to discharge excess yellow pulp water, and standing to solidify to form tofu; S5: Dehydrating the okara obtained in step S3 to obtain dehydrated okara, and crushing the dehydrated okara again.

[0006] Preferably, in step S5, the vegetable protein is extracted from the refined dregs by salting out, organic solvent dissolution or acid water dissolution, and the extracted vegetable protein is purified; the purified vegetable protein is dried and moisture is removed to obtain solid vegetable protein.

[0007] Preferably, the specific drying method includes hot air drying, vacuum drying or freeze drying.

[0008] Preferably, in step S5, the partially or completely dehydrated bean dregs are carbonized, including using a drying device to reduce the moisture content to a predetermined level to obtain dried bean dregs, crushing the dried bean dregs and feeding them into a continuous carbonization furnace for carbonization, cooling the carbonized product, and removing impurities and incompletely carbonized parts by screening to obtain biochar.

[0009] Preferably, in step S5, the method for obtaining the dehydrated bean dregs can be mechanical pressing or natural airing.

[0010] Preferably, in step S2, the salt precipitant may be selected from edible salt, sea salt or edible vinegar, and when the mass of the soybean powder precipitate is 500 grams, the amount of water added is 5 liters, the volume of the urease-rich solution obtained after the first filtration is 4-4.5 liters, and the mass of the soybean powder precipitate is 1000-1500 grams.

[0011] Preferably, in step S3, the ratio of bean powder precipitate to water is 1:5 for secondary stirring, and a gauze filter is used for the secondary filtration operation. The present invention has the following beneficial effects: Efficient use of resources: This method maximizes the use of resources by grinding dry soybeans into fine soybean powder and extracting urease and making tofu separately. In the traditional tofu production process, soybean dregs are often regarded as waste, and this method further explores the potential value of soybean dregs.

[0012] Effective extraction of urease: By adding salt precipitants for precipitation treatment, this method can efficiently extract urease from soybeans. Urease plays an important role in many industrial applications, such as feed additives, water quality treatment in the field of environmental protection, etc., so its extraction is of great significance for increasing the added value of products.

[0013] Additional product value-added: In step S5, by further processing the dregs, plant protein can be extracted and purified to obtain a solid plant protein product. This not only increases the diversity of products, but also improves the overall economic benefits. In addition, the partially or completely dehydrated dregs are carbonized to obtain biochar. Biochar is widely used in the fields of soil improvement and environmental protection, further broadening the market for the product.

[0014] Improved tofu quality: Through fine grinding, stirring, filtering and boiling, this method can produce tofu with fine texture and good taste. At the same time, the excess yellow pulp water is discharged by adding brine and applying pressure, which further ensures the shaping and quality of tofu.

[0015] Environmental protection and energy saving: This method focuses on the recycling of resources and the treatment of waste during the production process, such as reducing waste emissions by extracting urease and plant protein and making biochar. At the same time, the drying process uses hot air drying, vacuum drying or freeze drying, and the most energy-saving method can be selected according to actual conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a principle block diagram of the urease extraction-tofu production combined preparation method of the present invention; DETAILED DESCRIPTION The technical solution of the present invention is described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0017] Please refer to Figure 1 The present invention provides a urease extraction-tofu production combined preparation method, which, through a series of carefully designed steps, not only achieves effective urease extraction, but also makes full use of waste materials in the soy product production process, reduces production costs and reduces environmental pollution. The following is a detailed description of a specific embodiment of the present invention.

[0018] S1: Crush and grind dry soybeans into fine bean powder, and store the ground fine bean powder First, select high-quality dry soybeans as raw materials. These soybeans should be free of impurities, mildew, and maintain high nutritional value. Wash the dry soybeans to remove dust and impurities on the surface, then put them into a crusher for crushing, and further grind them into fine bean powder through a grinder. In order to ensure the uniformity and fineness of the fine bean powder, the speed and grinding time of the crusher and grinder can be adjusted. After grinding, the obtained fine bean powder is stored in a sealed container to prevent it from getting damp or deteriorating, so as to facilitate subsequent use.

[0019] S2: Add the ground bean powder into water, stir thoroughly until evenly mixed, add salt precipitant to the mixture for precipitation treatment, filter and separate the bean powder precipitation at the bottom layer and the urease solution at the top layer, extract and store the urease solution The stored fine bean powder is added to water in a certain proportion, and a stirrer is used to fully stir until a uniform mixture is formed. In a preferred embodiment of the present invention, when the mass of the bean powder precipitation is 500 grams, the amount of water added is 5 liters. After stirring, a salt precipitation agent is added to the mixture for precipitation treatment. The salt precipitation agent can be selected from one of edible salt, sea salt or edible vinegar, and these salt precipitation agents can effectively promote protein precipitation, thereby dissolving urease in the upper solution.

[0020] After the precipitation treatment is completed, the first filtering operation is performed. Use a special filtering device, such as a plate and frame filter press or a centrifugal filter, to filter and separate the mixture. After the first filtration, the bean powder precipitation in the lower layer and the urease solution in the upper layer can be obtained. In a preferred embodiment of the present invention, the volume of the urease-rich solution obtained after the first filtration is 4-4.5 liters, and the mass of the bean powder precipitation is 1000-1500 grams. By adjusting the type and addition amount of the salt precipitant, as well as the parameters of the filtering device, the precipitation and filtering effects can be optimized and the extraction efficiency of urease can be improved.

[0021] The obtained urease solution is stored for subsequent use. During storage, care should be taken to maintain the stability and activity of the solution and avoid it being affected by adverse factors such as light and high temperature.

[0022] S3: Add the soy powder precipitate obtained by the first filtration back into the water for a second stirring, and then separate the raw soy milk and the dregs through a second filtration after forming a slurry, and repeat this second filtration process at least once to ensure sufficient separation. The bean powder precipitate obtained by the first filtration is added back into the water for secondary stirring. In a preferred embodiment of the present invention, the bean powder precipitate is stirred for the second time at a ratio of 1:5 to water. After the stirring is completed, a slurry is formed. Then, the slurry is separated into raw soybean milk and bean dregs by a secondary filtration operation. In order to ensure sufficient separation, this secondary filtration process can be repeated at least once. In a preferred embodiment of the present invention, the secondary filtration operation uses a gauze filter to filter to ensure the filtering effect.

[0023] Through the secondary filtration operation, relatively pure raw soy milk and cellulose-rich dregs can be obtained. Raw soy milk can be used to make soy products such as tofu, while dregs can be further utilized to extract plant protein or prepare biochar.

[0024] S4: The raw soy milk is heated and boiled to be converted into cooked soy milk, and brine is slowly added to stir the soy milk until the soy milk solidifies into flocculent tofu blanks, and the flocculent tofu blanks are transferred to a tofu box covered with gauze, and pressure is applied to discharge excess yellow slurry, and the tofu is allowed to stand and solidify to form tofu. The raw soybean milk is heated and boiled. A dedicated heating device, such as a steam generator or an electric heater, is used to heat the raw soybean milk to a boiling state. During the boiling process, the heating speed and heating time should be controlled to avoid excessive boiling of the soybean milk and loss of nutrients.

[0025] After boiling, the brine is added. Pour the cooked soy milk into a special tofu mold, and then slowly add brine to make the tofu brine. The amount of brine added should be adjusted according to the amount of soy milk and the desired tofu taste. The brine addition operation can make the protein in the soy milk coagulate and form a flocculent tofu blank.

[0026] Next, the flocculent tofu is transferred to a tofu box covered with gauze. Then, a special pressing device is used to apply pressure to the tofu to drain the excess yellow pulp water. During the pressing process, the pressing speed and pressing time should be controlled to ensure that the texture and taste of the tofu meet the requirements. After the pressing is completed, the tofu is left to solidify to form the final tofu product.

[0027] S5: Dehydrate the dregs obtained in step S3 to obtain dehydrated dregs, and grind the dehydrated dregs again. The bean dregs obtained from step S3 are first dehydrated. The dehydration method may be mechanical pressing or natural airing. In a preferred embodiment of the present invention, the bean dregs are dehydrated by mechanical pressing or natural airing to reduce the water content thereof for subsequent processing.

[0028] After dehydration, the dehydrated okara is crushed and refined. Use a special crusher or grinder to crush the dehydrated okara into smaller particles. The refined okara can be used to extract plant protein or make biochar, etc.

[0029] Extraction and purification of plant protein As one of the preferred embodiments of the present invention, the vegetable protein can be extracted from the refined dregs by using salting out, organic solvent dissolution or acid water dissolution. These methods can effectively dissolve the vegetable protein in the dregs to form a vegetable protein solution.

[0030] After the extraction is completed, the plant protein solution is purified. The purification method can be centrifugation, ultrafiltration, dialysis or electrophoresis. Through the purification operation, impurities and proteins in the plant protein solution can be removed to improve the purity and quality of the plant protein.

[0031] The purified vegetable protein solution can be dried to remove moisture therein. The drying method can be hot air drying, vacuum drying or freeze drying. In a preferred embodiment of the present invention, the vegetable protein solution is dried by hot air drying, vacuum drying or freeze drying to obtain a solid vegetable protein product. The drying process can not only remove moisture from the vegetable protein, but also improve its stability and shelf life.

[0032] Preparation and Utilization of Biochar As one of another preferred embodiments of the present invention, the partially or completely dehydrated bean dregs can be carbonized to prepare biochar. First, a drying device is used to reduce the moisture content of the dehydrated bean dregs to a predetermined level to obtain dried bean dregs. In a preferred embodiment of the present invention, the moisture content of the dried bean dregs is reduced to less than 10%.

[0033] Then, the dried bean dregs are crushed and sent to a continuous carbonization furnace for carbonization. During the carbonization process, the dried bean dregs undergo pyrolysis and polycondensation reactions at high temperatures to form biochar. After the carbonization is completed, the carbonized product is cooled. The cooling method can be natural cooling or forced cooling.

[0034] After cooling, the biochar is screened. Use special screening equipment to grade the biochar and remove impurities and incompletely carbonized parts. Through screening, high-purity biochar products can be obtained.

[0035] Biochar has a wide range of application prospects. It can be used as a soil conditioner to improve soil fertility and air permeability; it can also be used as an adsorbent to treat wastewater and waste gas; in addition, biochar can also be used as a form of biomass energy for power generation or heating.

[0036] Example 1 Take 500g of dry soybeans, wash them, crush them and grind them into soybean powder for later use. Add the ground 500g soybean powder into 5L water and stir evenly, then add an appropriate amount of sea salt as a precipitant for precipitation. After precipitation, perform the first filtration operation to obtain 1060g of lower soybean powder precipitation and 4.1L of upper urease solution. The activity of the upper urease solution was measured to be 10.6mM / min.

[0037] The obtained 1060g soybean powder precipitate is added back into 5L water for secondary stirring to form a slurry, and then secondary filtration is performed through a gauze filter to obtain raw soybean milk and soybean dregs. The raw soybean milk is heated and boiled and converted into cooked soybean milk, and then a brine is added to obtain a flocculent tofu blank. The tofu blank is transferred to a tofu box paved with gauze, and pressure is applied to discharge excess yellow slurry water, and then the tofu blank is allowed to stand and solidify to form a tofu product.

[0038] The bean dregs obtained by the secondary filtration are dehydrated by mechanical pressing or natural drying to obtain dehydrated bean dregs. The dehydrated bean dregs are crushed and refined again, and the plant protein therein is extracted by salting out, organic solvent or acid water dissolution and purified. Finally, the purified plant protein is hot-air dried, vacuum dried or freeze-dried to obtain a solid plant protein product.

[0039] Example 2 Similar to Example 1, 500 g of dry soybeans are washed, crushed and ground into soybean powder for use, and the subsequent precipitation, filtration, boiling, brine and tofu making steps are performed. The difference is that the bean dregs obtained by the secondary filtration are quickly dried in a dryer to reduce the moisture content to less than 10%. The dried bean dregs are then crushed and carbonized in a continuous carbonization furnace. After the carbonization is completed, the bean dregs are cooled and the impurities and incompletely carbonized parts are removed by screening to finally obtain a high-purity biochar product.

[0040] By implementing the method provided by the present invention, not only can high-activity urease solution be effectively extracted, but also waste materials such as bean dregs in the production process of soy products can be fully utilized to prepare valuable products such as plant protein and biochar, which not only reduces production costs but also reduces the risk of environmental pollution and improves the economic and social benefits of the enterprise.

[0041] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A urease extraction-tofu production combined preparation method, characterized in that: The following steps are involved: S1: crushing and grinding dry soybeans into fine bean powder, and storing the ground fine bean powder; S2: adding the ground fine bean powder into water, stirring thoroughly until uniformly mixed, adding a salt precipitant into the mixture for precipitation treatment, filtering for the first time to separate the bean powder precipitate at the lower layer and the urease solution at the upper layer, extracting and storing the urease solution; S3: adding the bean powder precipitate obtained by the first filtration back into the water for a second stirring to form a slurry, and then performing a second filtration to separate the raw soy milk and the bean dregs, and repeating the second filtration process at least once to ensure sufficient separation; S4: heating and boiling the obtained raw soybean milk to convert it into cooked soybean milk, stirring and slowly adding brine to brine until the soybean milk solidifies into flocculent tofu blanks, transferring the flocculent tofu blanks into a tofu box covered with gauze, applying pressure to discharge excess yellow pulp water, and standing to solidify to form tofu; S5: Dehydrating the okara obtained in step S3 to obtain dehydrated okara, and crushing the dehydrated okara again.

2. The urease extraction-tofu production combined preparation method according to claim 1, characterized in that: In step S5, the vegetable protein is extracted from the refined dregs by salting out, organic solvent dissolution or acid water dissolution, and the extracted vegetable protein is purified; the purified vegetable protein is dried and moisture is removed to obtain solid vegetable protein.

3. The urease extraction-tofu production combined preparation method according to claim 2, characterized in that: Specific methods of drying include hot air drying, vacuum drying or freeze drying.

4. The urease extraction-tofu production combined preparation method according to claim 1, characterized in that: In step S5, the partially or completely dehydrated bean dregs are carbonized, including using a drying device to reduce the moisture content to a predetermined level to obtain dried bean dregs, crushing the dried bean dregs and sending them into a continuous carbonization furnace for carbonization, cooling the carbonized product, and removing impurities and incompletely carbonized parts by screening to obtain biochar.

5. The urease extraction-tofu production combined preparation method according to claim 1, characterized in that: In step S5, the method for obtaining the dehydrated bean dregs can be mechanical pressing or natural drying.

6. The urease extraction-tofu production combined preparation method according to claim 1, characterized in that: In step S2, the salt precipitant can be selected from edible salt, sea salt or edible vinegar, and when the mass of the soybean powder precipitate is 500 grams, the amount of water added is 5 liters, the volume of the urease-rich solution obtained after the first filtration is 4-4.5 liters, and the mass of the soybean powder precipitate is 1000-1500 grams.

7. The urease extraction-tofu production combined preparation method according to claim 1, characterized in that: In step S3, the ratio of bean powder precipitate to water is 1:5 and secondary stirring is performed, and a gauze filter is used for the secondary filtration operation.

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