Soybean milk preparation method, soybean milk, utilization method of soybean milk preparation byproducts and lipase

Abstract

The invention provides a preparation method of soymilk, the soymilk, a utilization method of soymilk preparation byproducts and lipase, the preparation method of the soymilk comprises the following steps: mixing soybean powder with water, and then sequentially performing extraction, grinding and sieving to prepare a mixed material liquid; mixing the mixed material liquid with a solvent, and performing extraction separation to prepare soybean milk and lipase; the solvent comprises a hydrogen bond donor and a hydrogen bond acceptor, the hydrogen bond donor comprises proline, and the hydrogen bond acceptor comprises lactic acid; carrying out enzyme deactivation treatment and sieving treatment on the soybean milk in sequence, and adding auxiliary materials into a screen underflow to prepare a semi-finished product; and sequentially carrying out homogenization treatment and sterilization treatment on the semi-finished product to prepare the soymilk. According to the preparation method, the soybean lipase in the soymilk is extracted by using the natural eutectic solvent, so that effective separation of the lipase and the soymilk is realized, continuous fat oxidation reaction and bad flavor caused by long-term contact of the lipase and the soymilk are avoided, meanwhile, the fresh taste and flavor of the soymilk are further effectively improved, and the shelf life is more stable.

Description

Technical Field

[0001] The present application relates to the technical field of food processing, and in particular to a method for preparing soy milk, soy milk, a method for utilizing by-products of soy milk preparation, and lipase. Background Art

[0002] Soy milk prepared by traditional soy milk preparation process generally has undesirable flavors such as bean green smell and beany smell, and fat oxidation smell during the shelf life. The main reason is that the lipase in the soy milk and the oil undergo oxidation reaction, which causes the product to have undesirable flavors such as bean green smell and beany smell, and fat oxidation smell during the shelf life. Currently, most of the endogenous enzymes such as urease and lipase in soy milk are inactivated by high temperature inactivation, but excessively high temperature treatment will also lead to the appearance of undesirable flavors in soy milk and accelerate deterioration during the shelf life.

[0003] Therefore, how to improve the sensory quality and shelf life stability of soy milk is an urgent problem to be solved. Summary of the invention

[0004] Based on this, the present application provides a method for preparing soy milk, soy milk, a method for utilizing by-products of soy milk preparation, and lipase, so as to improve the sensory quality and shelf life stability of soy milk.

[0005] The first aspect of the present application provides a method for preparing soy milk, comprising the following steps:

[0006] The soybean powder is mixed with water, and then extracted, ground and sieved in sequence to prepare a mixed liquid;

[0007] The mixed liquid is mixed with a solvent and then extracted and separated to prepare soybean milk and lipase; the solvent comprises a hydrogen bond donor and a hydrogen bond acceptor, the hydrogen bond donor comprises proline, and the hydrogen bond acceptor comprises lactic acid;

[0008] The soymilk is subjected to enzyme inactivation and sieving in sequence, and auxiliary materials are added to the sieve to prepare a semi-finished product;

[0009] The semi-finished product is subjected to homogenization and sterilization treatments in sequence to prepare the soy milk.

[0010] In some embodiments, the molar ratio of the hydrogen bond donor to the hydrogen bond acceptor in the solvent is 1:(1-2); and / or

[0011] The solvent further comprises water, and the mass proportion of the water in the solvent is 3%-5%; and / or

[0012] The mass percentage of the solvent relative to the mass percentage of the mixed liquid is 30%-50%; and / or

[0013] The extraction and separation process comprises: stirring the mixed material and the solvent for 5 minutes to 10 minutes, and then centrifuging at 6000 rpm to 12000 rpm for 5 minutes to 10 minutes.

[0014] In some embodiments, the mass volume ratio of the soybean flour to water is 1 kg: (4-8) L; and / or

[0015] The leaching temperature is 65°C-75°C and the leaching time is 10min-60min; and / or

[0016] The mesh number of the sieve used for the grinding and screening is 120 meshes-200 meshes.

[0017] In some embodiments, the temperature of the enzyme inactivation treatment is 80°C-90°C, and the time is 10min-30min; and / or

[0018] The mesh size of the sieve used in the sieving process is 150-200 mesh; and / or

[0019] The auxiliary materials include white sugar; and / or

[0020] The mass percentage of the auxiliary material relative to the mass of the undersize obtained by the screening process is 3.5%-5.5%.

[0021] In some embodiments, the homogenization process is performed at a pressure of 30 MPa-50 MPa, a temperature of 70° C.-80° C., a time of 2 min-5 min, and a number of times of two times; and / or

[0022] The sterilization treatment is carried out at a temperature of 130° C. to 150° C. and for a time of 8 s to 20 s.

[0023] The second aspect of the present application provides a soy milk prepared by the preparation method of the first aspect of the present application;

[0024] Optionally, the protein content in the soy milk is ≥2.1wt%, and the soluble solid content is 10wt%-15wt%.

[0025] The third aspect of the present application provides a method for utilizing by-products of soy milk preparation, the method comprising the following steps:

[0026] The byproduct of soy milk preparation is mixed with a solvent to prepare a mixed material; the byproduct of soy milk preparation includes soybean hull powder and soybean dregs powder; the solvent includes a hydrogen bond donor and a hydrogen bond acceptor, the hydrogen bond donor includes proline, and the hydrogen bond acceptor includes lactic acid and / or glycerol;

[0027] The mixed material is sequentially subjected to stirring treatment and centrifugal treatment, and the supernatant obtained from the centrifugal treatment is taken.

[0028] In some embodiments, the molar ratio of the hydrogen bond donor to the hydrogen bond acceptor in the solvent is 1:(1-2); and / or

[0029] The solvent further comprises water, and the mass proportion of the water in the solvent is 3%-5%; and / or

[0030] The mass percentage of the soymilk preparation by-product relative to the mass percentage of the solvent is 20%-50%; and / or

[0031] The mass ratio of the soybean hull powder to the soybean dregs powder in the soymilk preparation by-product is 1:(1-3).

[0032] In some embodiments, the stirring time is 10 min-60 min, and the rotation speed is 1500 r / min-2500 r / min; and / or

[0033] The rotation speed of the centrifugal treatment is 6000r / min-12000r / min, and the time is 5min-10min.

[0034] The fourth aspect of the present application provides a lipase prepared by the method for utilizing a by-product of soy milk preparation according to the third aspect of the present application.

[0035] The preparation method of soy milk provided above adopts a natural low eutectic solvent containing a hydrogen bond donor (proline) and a hydrogen bond acceptor (lactic acid). The preparation method uses a natural low eutectic solvent to extract soybean lipase from soy milk, realizes effective separation of lipase and soy milk, avoids long-term contact of lipase with soy milk, causes continuous oil oxidation reaction, and produces bad flavor, and also further reduces the probability of soy milk causing shelf life deterioration acceleration reaction due to excessive enzyme inactivation heat intensity, effectively improves the fresh taste and flavor of soy milk, and makes the shelf life more stable. In addition, compared with traditional solvents, the solvent also has the advantages of safety, non-toxicity, green and environmental protection, which improves the safety of the preparation method. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application and to more completely understand the present application and its beneficial effects, the following is a brief introduction to the drawings required for the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on these drawings without creative work.

[0037] Figure 1 The present invention is a flow chart of a soy milk preparation method and a method for utilizing soy milk preparation by-products provided in one embodiment. DETAILED DESCRIPTION

[0038] For ease of understanding of the present application, the present application will be described more fully below with reference to the relevant embodiments. The following provides preferred embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0040] The terms "and / or", "or / and", and "and / or" used herein include any one of two or more related listed items, and also include any and all combinations of the related listed items, wherein the any and all combinations include any combination of two related listed items, any more related listed items, or all related listed items. It should be noted that when at least three items are connected by at least two conjunctions selected from "and / or", "or / and", and "and / or", it should be understood that in the present application, the technical solution undoubtedly includes technical solutions connected by "logical and", and also undoubtedly includes technical solutions connected by "logical or".

[0041] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0042] In this application, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are deemed to be continuous and include the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0043] Only some numerical ranges are specifically disclosed herein. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, and likewise any upper limit can be combined with any other upper limit to form an unspecified range. In addition, each separately disclosed point or single value can itself be combined as a lower limit or upper limit with any other point or single value or with other lower limits or upper limits to form an unspecified range.

[0044] The temperature parameters in this application, unless otherwise specified, allow both constant temperature treatment and treatment within a certain temperature range. The constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. Fluctuations within the range of ±5°C, ±4°C, ±3°C, ±2°C, and ±1°C are allowed.

[0045] Herein, the “suitable” mentioned in “suitable combination”, “suitable method”, “any suitable method”, etc., shall be based on the ability to implement the technical solution of this application, solve the technical problems of this application, and achieve the expected technical effects of this application.

[0046] In the present application, "further", "further", "particularly" and the like are used for descriptive purposes to indicate differences in content, but should not be construed as limiting the scope of protection of the present application.

[0047] In this application, "optionally", "optional", and "optional" mean optional or dispensable, that is, any one of the two parallel schemes of "yes" or "no". If multiple "options" appear in a technical solution, unless otherwise specified and there is no contradiction or mutual restriction, each "optional" is independent.

[0048] In the description of the application, "plurality" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0049] If there is no special description, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution. If there is no special description, all technical features and optional technical features of the present application can be combined with each other to form a new technical solution.

[0050] If there is no special explanation, all the steps of the present application can be performed sequentially or randomly, preferably sequentially.

[0051] Soy milk prepared by traditional soy milk preparation process generally has undesirable flavors such as bean green smell and beany smell, and fat oxidation smell during the shelf life. The main reason is that the lipase and oil in the soy milk undergo oxidation reaction, resulting in undesirable flavors such as bean green smell and beany smell, and fat oxidation smell during the shelf life. Currently, most endogenous enzymes such as urease and lipase in soy milk are inactivated by high temperature inactivation, but excessive temperature treatment will also lead to the appearance of undesirable flavors in soy milk and accelerated deterioration during the shelf life. Therefore, under the premise of ensuring food safety, effectively reducing the heat intensity of soy milk can further improve the flavor and shelf life stability of soy milk.

[0052] In the existing traditional soy milk production process, a large number of by-products such as bean skins and bean dregs are inevitably produced. For a long time, the by-products of soy milk production have not been effectively utilized in a high-value manner, and most of them have been discarded as waste or used as low-value feed. Therefore, it is of great significance to develop new technologies for high-value utilization of soy milk production by-products, which can not only create higher economic benefits for enterprises, but also effectively solve problems such as resource waste and environmental pollution. Studies have found that soybeans and their processing by-products, bean skins and bean dregs, usually contain rich lipase, but they have not been fully developed and utilized for a long time. Therefore, the development of a new green and efficient lipase extraction method is conducive to promoting the high-value utilization of bean skins and bean dregs, which are by-products of the soy milk production process.

[0053] Lipase products have broad application scenarios in the fields of oils, food, medicine, cosmetics, etc. In the food industry, they can be used in oil refining, dairy product flavoring and other fields. Its source can be prepared by traditional extraction methods. Traditional lipase extraction methods are mainly water extraction and phosphate buffer extraction. The main disadvantages of traditional methods are low extraction efficiency, high time cost, and the lipase extracted by this method has low activity and poor stability, which is not conducive to industrial production and application.

[0054] Therefore, how to improve the sensory quality and shelf life stability of soy milk and utilize the by-products of soy milk preparation are issues that need to be urgently addressed.

[0055] Based on the above problems, the present application utilizes a natural low eutectic solvent to separate and extract lipase from soy milk, which can effectively reduce the lipase content in soy milk, thereby reducing the adverse effects of high-temperature enzyme inactivation in soy milk, effectively improving the fresh taste and flavor of soy milk, making the shelf life more stable, and also saving energy and costs for the enterprise.

[0056] This application also uses natural low-co-soluble solvents to extract lipase from soy milk production by-products such as soy skin and dregs, solving the problems of low extraction efficiency, low lipase activity, and poor stability of traditional extraction methods, effectively improving the extraction efficiency and effect, and at the same time providing new ideas and directions for realizing the high-value utilization of soy milk production by-products.

[0057] One or more embodiments of the present application provide a method for preparing soy milk, comprising the following steps: mixing soybean powder with water, extracting, grinding and screening in sequence to prepare a mixed liquid; mixing the mixed liquid with a solvent, extracting and separating the mixed liquid to prepare soy milk and lipase; the solvent comprises a hydrogen bond donor and a hydrogen bond acceptor, the hydrogen bond donor comprises proline, and the hydrogen bond acceptor comprises lactic acid; performing enzyme inactivation treatment and screening on the soy milk in sequence, adding auxiliary materials to the sieve to prepare a semi-finished product; performing homogenization treatment and sterilization treatment on the semi-finished product in sequence to prepare soy milk.

[0058] Understandably, the soy milk preparation method uses a natural low eutectic solvent containing a hydrogen bond donor (proline) and a hydrogen bond acceptor (lactic acid). The preparation method uses a natural low eutectic solvent to extract soybean lipase from soy milk, achieving effective separation of lipase and soy milk, avoiding long-term contact of lipase with soy milk, resulting in continuous oil oxidation reaction and bad flavor, while also further reducing the probability of soy milk causing accelerated reaction during shelf life due to excessive heat intensity for enzyme inactivation, effectively improving the fresh taste and flavor of soy milk, and making the shelf life more stable. In addition, compared with traditional solvents, the solvent also has the advantages of safety, non-toxicity, green environmental protection, and recyclability, which improves the safety of the soy milk preparation method.

[0059] It should be noted that the solvent containing hydrogen bond donors (proline) and hydrogen bond acceptors (lactic acid) used in the soy milk preparation method is a natural low eutectic solvent. "Natural low eutectic solvent" refers to a uniform and stable liquid prepared by mixing metabolic products in organisms such as sugars, organic acids, amino acids, alcohols and amines as hydrogen bond donors (HBD) or hydrogen bond acceptors (HBA) in a certain proportion. Compared with traditional solvents, natural low eutectic solvents have the advantages of low volatility, non-flammability, safety, non-toxicity, and biodegradability.

[0060] In some embodiments, the molar ratio of hydrogen bond donors to hydrogen bond acceptors in the solvent is 1:(1-2); for example, it can be but not limited to 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2 or the range between any two of the above ratios. When the molar ratio of hydrogen bond donors to hydrogen bond acceptors in the solvent is within the above range, the preparation conditions of the natural low eutectic solvent are relatively mild, and the lipase extraction rate is high. As a possible embodiment, the solvent also includes water, and the mass proportion of water in the solvent is 3%-5%; for example, it can be but not limited to 3%, 3.2%, 3.4%, 3.6%, 3.8%, 4%, 4.2%, 4.4%, 4.6%, 4.8%, 5% or the range between any two of the above mass proportions. When the mass ratio of water in the solvent is within the above range, the synthesis efficiency is higher when preparing the natural low eutectic solvent, which can effectively reduce the production cost; at the same time, it can effectively improve the extraction efficiency of the solvent for lipase. When the water content is too low, the natural low eutectic solvent will have a greater viscosity and even form crystals; when the water content is too high, the viscosity of the natural low eutectic solvent will be reduced, and the hydrogen bond structure in the natural low eutectic solvent will also be disintegrated, and the natural low eutectic solvent suitable for lipase extraction cannot be formed.

[0061] In some embodiments, the mass percentage of the solvent relative to the mass percentage of the mixed liquid is 30%-50%; for example, it can be but not limited to 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50% or the range between any two of the above percentages, etc. When the mass percentage of the natural low eutectic solvent relative to the mass percentage of the mixed liquid is within the above range, the extraction efficiency of lipase is high.

[0062] As a possible implementation, the extraction and separation process includes: stirring the mixed material and the solvent for 5 min-10 min, and then centrifuging at 6000 rpm-12000 rpm for 5 min-10 min.

[0063] As a non-limiting example, the stirring time after mixing the mixture and the solvent can be but is not limited to 5 min, 5.5 min, 6 min, 6.5 min, 7 min, 7.5 min, 8 min, 8.5 min, 9 min, 9.5 min, 10 min or a range between any two of the above times.

[0064] After the mixture and the solvent are mixed, the stirring rate is 1500r / min-2500r / min; for example, it can be but not limited to 1500r / min, 1600r / min, 1700r / min, 1800r / min, 1900r / min, 2000r / min, 2100r / min, 2200r / min, 2300r / min, 2400r / min, 2500r / min or a range between any two of the above rates.

[0065] As an example, the rotation speed of the centrifuge after stirring can be but is not limited to 6000 rpm, 7000 rpm, 8000 rpm, 9000 rpm, 10000 rpm, 11000 rpm, 12000 rpm or a range between any two of the above rotation speeds.

[0066] The centrifugation time after stirring can be but is not limited to 5 min, 5.5 min, 6 min, 6.5 min, 7 min, 7.5 min, 8 min, 8.5 min, 9 min, 9.5 min, 10 min or a range between any two of the above times.

[0067] It should be noted that the centrifugal speed and time can be combined in any suitable manner, and both can be selected from any centrifugal speed and time described in this article.

[0068] In some embodiments, the mass volume ratio of soybean meal to water is 1kg:(4-8)L. For example, it may be, but is not limited to, 1kg:4L, 1kg:4.5L, 1kg:5L, 1kg:5.5L, 1kg:6L, 1kg:6.5L, 1kg:7L, 1kg:7.5L, 1kg:8L or a range between any two of the above mass volume ratios. When the mass volume ratio of soybean meal to water is within the above range, the protein extraction rate is high and the production feasibility is high. When the material-water ratio is too low, the viscosity of the feed liquid is too large, which is not conducive to pipeline transportation and may even block the pipeline. At the same time, the protein in the material cannot be fully extracted; when the material-liquid ratio is too large, it is impossible to reserve sufficient water level to flush the pipeline, which on the one hand causes a waste of resources, and on the other hand, the protein content of the product will be lower than the national standard due to excessive water addition, resulting in unqualified products and no production feasibility.

[0069] In some embodiments, the temperature of the extraction after the soybean powder and water are mixed is 65°C-75°C; for example, it can be but not limited to 65°C, 66°C, 67°C, 68°C, 69°C, 70°C, 71°C, 72°C, 73°C, 74°C, 75°C or a range between any two of the above temperatures. When the extraction temperature is within the above range, it is beneficial to improve the flavor of the prepared soybean milk product and reduce the risk of microbial safety, and it is also beneficial to save production costs.

[0070] In some optional embodiments, the extraction time after the soybean powder and water are mixed is 10 min-60 min; for example, it can be but not limited to 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 5 min, 60 min or a range between any two of the above time periods, etc. When the extraction time is within the above range, the protein extraction rate and the sensory quality of the soybean milk product are good, and the production efficiency is high.

[0071] It should be noted that the centrifugal speed and time can be combined in any suitable manner, and both can be selected from any centrifugal speed and time described in this article.

[0072] As a possible implementation mode, when preparing the mixed liquid, the mesh size of the sieve used for grinding and screening is 120 mesh-200 mesh; for example, it can be but not limited to 120 mesh, 130 mesh, 140 mesh, 150 mesh, 160 mesh, 170 mesh, 180 mesh, 190 mesh, 200 mesh or a range between any two of the above mesh sizes, etc.

[0073] In some embodiments, the temperature for enzyme inactivation treatment of soy milk is 80°C-90°C; for example, it may be but is not limited to 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C, 90°C or a range between any two of the above temperatures.

[0074] As a possible implementation manner, the time for enzyme inactivation treatment of soy milk is 10 min-30 min; for example, it can be but not limited to 10 min, 12 min, 14 min, 16 min, 18 min, 20 min, 22 min, 24 min, 26 min, 28 min, 30 min or a range between any two of the above times.

[0075] It should be noted that the temperature and time for the enzyme inactivation treatment of soy milk can be combined in any appropriate manner, and both can be selected from any temperature and time for the enzyme inactivation treatment of soy milk described in this article.

[0076] In some embodiments, the mesh size of the sieve used for sieving the enzyme-inactivated soymilk is 150-200 mesh; for example, it may be but not limited to 150 mesh, 160 mesh, 170 mesh, 180 mesh, 190 mesh, 200 mesh, or a range between any two of the above mesh sizes.

[0077] In some optional embodiments, the auxiliary material includes white sugar.

[0078] In some embodiments, the mass of the auxiliary material relative to the mass of the screened material obtained by screening is 3.5%-5.5%; for example, it can be but not limited to 3.5%, 3.6%, 3.8%, 4%, 4.2%, 4.4%, 4.6%, 4.8%, 5%, 5.2%, 5.4%, 5.5% or the range between any two of the above values.

[0079] In some embodiments, the pressure during homogenization of the semi-finished product is 30MPa-50MPa; for example, it may be, but not limited to, 30MPa, 32MPa, 34MPa, 36MPa, 38MPa, 40MPa, 42MPa, 44MPa, 46MPa, 48MPa, 50MPa, or a range between any two of the above pressures, etc. When the pressure of the homogenization treatment is within the above range, the prepared soy milk product has a delicate and smooth taste.

[0080] As a possible implementation, the temperature for homogenizing the semi-finished product is 70°C-80°C; for example, it may be, but not limited to, 70°C, 72°C, 74°C, 76°C, 78°C, 80°C, or a range between any two of the above temperatures. When the temperature of the homogenization treatment is within the above range, the safety risk of microorganisms can be effectively reduced, while having little effect on the sensory quality of the product.

[0081] In some embodiments, the semi-finished product is homogenized for 3 minutes.

[0082] It should be noted that the pressure, temperature and time of the homogenization treatment can be combined in any appropriate manner, and the three can be selected from any pressure, temperature and time of the homogenization treatment described in this article.

[0083] In some exemplary embodiments, the homogenization process is performed twice.

[0084] In some embodiments, the sterilization temperature is 130°C-150°C; for example, it can be but not limited to 130°C, 132°C, 134°C, 136°C, 138°C, 140°C, 142°C, 144°C, 146°C, 148°C, 150°C or a range between any two of the above temperatures.

[0085] As a possible implementation manner, the sterilization treatment time is 8s-20s; for example, it can be but not limited to 8s, 10s, 12s, 14s, 16s, 18s, 20s or a range between any two of the above times.

[0086] It should be noted that the temperature and time of the sterilization treatment can be combined in any appropriate manner, and both can be selected from any temperature and time of the sterilization treatment described in this article.

[0087] As a non-limiting example, the method for preparing soybean flour includes: peeling soybeans and then crushing them through a 20-mesh sieve.

[0088] As a possible implementation, the particle size of the soybean powder is ≤0.85 mm.

[0089] In some optional embodiments, the soybeans are non-genetically modified soybeans that are selected to be clean and free of impurities.

[0090] One or more embodiments of the present application provide a soy milk prepared by the above-mentioned preparation method. The obtained soy milk is milky white, has a strong milky flavor, a smooth taste and a moderate sweetness.

[0091] In some optional embodiments, the protein content in the soy milk is ≥ 2.1 wt %.

[0092] In some embodiments, the soluble solids content in the soy milk is 10wt%-15wt%; for example, it can be but not limited to 10wt%, 12wt%, 13wt%, 14wt%, 15wt% or a range between any two of the above values.

[0093] One or more embodiments of the present application provide a method for utilizing byproducts of soy milk preparation, the method comprising the following steps:

[0094] The by-product of soy milk preparation is mixed with a solvent to prepare a mixed material; the mixed material is stirred and centrifuged in sequence, and the supernatant obtained by the centrifugation is taken; the by-product of soy milk preparation includes soybean hull powder and soybean dregs powder; the solvent includes a hydrogen bond donor and a hydrogen bond acceptor, the hydrogen bond donor includes proline, and the hydrogen bond acceptor includes lactic acid and / or glycerol.

[0095] It should be noted that the "soy milk preparation by-products" mentioned above refer to by-products produced in the process of soy milk preparation; for example, bean skin and bean dregs.

[0096] Understandably, the utilization method uses a natural low eutectic solvent containing a hydrogen bond donor (proline) and a hydrogen bond acceptor (lactic acid and / or glycerol), that is, the utilization method uses a natural low eutectic solvent to extract lipase from soy milk preparation byproducts such as bean skin and dregs, thereby realizing the high-value utilization of soy milk preparation byproducts; at the same time, the use of a natural low eutectic solvent to extract lipase can further improve the extraction efficiency, and the initial activity and stability of the lipase extracted by this method are higher than those of the traditional water extraction method and the phosphate buffer extraction method. Therefore, the use of a natural low eutectic solvent to extract soybean lipase can obtain a lipase with higher initial enzyme activity and better stability, which also provides a broader space for the industrial application of lipase.

[0097] It should be noted that the solvent containing hydrogen bond donors (proline) and hydrogen bond acceptors (lactic acid and / or glycerol) used in the method for utilizing by-products of soy milk preparation is also a natural low eutectic solvent. "Natural low eutectic solvent" refers to a uniform and stable liquid prepared by mixing metabolic products in organisms such as sugars, organic acids, amino acids, alcohols and amines as hydrogen bond donors (HBD) or hydrogen bond acceptors (HBA) in a certain proportion. Compared with traditional solvents, natural low eutectic solvents have the advantages of low volatility, non-flammability, safety, non-toxicity, and biodegradability. In some embodiments, the molar ratio of hydrogen bond donors to hydrogen bond acceptors in the solvent is 1: (1-2); for example, it can be but not limited to 1: 1, 1: 1.1, 1: 1.2, 1: 1.3, 1: 1.4, 1: 1.5, 1: 1.6, 1: 1.7, 1: 1.8, 1: 1.9, 1: 2 or the range between any two of the above ratios. When the molar ratio of the hydrogen bond donor to the hydrogen bond acceptor in the solvent is within the above range, the preparation conditions are relatively mild and the lipase extraction rate is high.

[0098] As a possible embodiment, the solvent also includes water, and the mass proportion of water in the solvent is 3%-5%; for example, it can be but not limited to 3%, 3.2%, 3.4%, 3.6%, 3.8%, 4%, 4.2%, 4.4%, 4.6%, 4.8%, 5% or the range between any two of the above mass proportions. When the mass proportion of water in the solvent is within the above range, the efficiency of preparing the natural low eutectic solvent is higher, which can effectively reduce the production cost and effectively improve its extraction efficiency of lipase. When the water content is too low, the natural low eutectic solvent will have a greater viscosity and even form crystals; when the water content is too high, the viscosity of the natural low eutectic solvent will be reduced, and the hydrogen bond structure in the natural low eutectic solvent will also be disintegrated, and a natural low eutectic solvent suitable for lipase extraction cannot be formed.

[0099] In some embodiments, the mass percentage of the byproduct of soy milk preparation relative to the mass percentage of the solvent is 20%-50%; for example, it can be but not limited to 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50% or a range between any two of the above values. When the mass percentage of the byproduct of soy milk preparation relative to the mass percentage of the solvent is within the above range, the extraction efficiency of lipase is high.

[0100] In some embodiments, the mass ratio of soybean husk powder to okara powder in the by-product of soy milk preparation is 1:(1-3); for example, it can be but not limited to 1:1, 1:1.2, 1:1.4, 1:1.6, 1:1.8, 1:2, 1:2.2, 1:2.4, 1:2.6, 1:2.8, 1:3 or a range between any two of the above ratios. When the mass ratio of soybean husk powder to okara powder in the by-product of soy milk preparation is within the above range, it is beneficial to further improve the extraction efficiency of the solvent for lipase.

[0101] In some embodiments, the mixing time of the mixed material is 10 min-60 min; for example, it can be but not limited to 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min or a range between any two of the above times.

[0102] As a possible implementation, the rotation speed of the mixed material during stirring is 1500 r / min-2500 r / min. For example, it may be, but is not limited to, 1500 r / min, 1600 r / min, 1700 r / min, 1800 r / min, 1900 r / min, 2000 r / min, 2100 r / min, 2200 r / min, 2300 r / min, 2400 r / min, 2500 r / min or a range between any two of the above rates.

[0103] In some optional embodiments, the rotation speed when the mixed material is centrifuged is 6000r / min-12000r / min; for example, it can be but not limited to 6000r / min, 6500r / min, 7000r / min, 7500r / min, 8000r / min, 8500r / min, 9000r / min, 9500r / min, 10000r / min, 10500r / min, 11000r / min, 11500r / min, 12000r / min or the range between any two of the above speeds.

[0104] As a possible implementation manner, the time for stirring the mixed material is 5 min-10 min; for example, it can be but not limited to 5 min, 6 min, 7 min, 8 min, 9 min, 10 min or a range between any two of the above time periods.

[0105] It should be noted that the rotation speed and time of the centrifugal treatment can be combined in any suitable manner, and both can be selected from any rotation speed and time of the centrifugal treatment described in this article.

[0106] In some embodiments, the method for preparing soybean hull powder comprises: crushing the soybean hulls and then passing the crushed soybean hulls through an 80-mesh sieve to obtain the powder.

[0107] As a possible implementation, the method for preparing okara powder includes: crushing the okara and passing it through an 80-mesh sieve to obtain the powder.

[0108] In some embodiments, the particle sizes of soybean hull powder and okara powder are each independently ≤177 μm.

[0109] One or more embodiments of the present application provide a lipase, which is prepared by the above-mentioned method for utilizing by-products of soy milk preparation.

[0110] The lipase has higher initial enzyme activity and more stable enzyme activity.

[0111] In some embodiments, the process of the soy milk preparation method and the method of utilizing the soy milk preparation by-product is as follows: Figure 1 As shown, the soy milk preparation method comprises: peeling soybeans, crushing and sieving to obtain soy flour; mixing the soy flour with water, extracting, grinding and sieving in sequence to obtain bean dregs and a mixed liquid; mixing the mixed liquid with a natural low eutectic solvent, extracting and separating to obtain soy milk and lipase; performing enzyme inactivation treatment and sieving on the soy milk in sequence, adding white sugar to the sieved material to obtain a semi-finished product; performing homogenization treatment and sterilization and filling on the semi-finished product in sequence to obtain soy milk.

[0112] The bean skin and bean dregs produced in the process of preparing soy milk are crushed and sieved respectively, and then mixed with a natural low eutectic solvent to prepare a mixed material; the mixed material is stirred and centrifuged in sequence, and the supernatant obtained by the centrifugation is used to prepare lipase.

[0113] The technical scheme of the present application is described in detail below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present application and are not used to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following embodiments are preferably referred to the guidance given in the present application, and can also be carried out according to the experimental manual or conventional conditions in the field, or according to the conditions recommended by the manufacturer, or with reference to experimental methods known in the art.

[0114] In the following specific embodiments, the measured parameters of raw material components may have slight deviations within the range of weighing accuracy unless otherwise specified. For temperature and time parameters, acceptable deviations caused by instrument test accuracy or operation accuracy are allowed.

[0115] 1. Preparation of Soy Milk

[0116] Example 1-1

[0117] Step S1: Select clean non-genetically modified soybeans without impurities, peel them, and grind them through a 20-mesh sieve to obtain soybean powder for later use.

[0118] Step S2, mixing the soybean powder in step S1 with water at a mass volume ratio of 1kg:5L, and then preserving at 70°C for 10 minutes for leaching. After the leaching is completed, grinding and passing through a 150-mesh sieve to obtain a mixed liquid for standby use.

[0119] Step S3, adding the soy milk in step S2 into a natural low eutectic solvent to extract and separate lipase to obtain soy milk and lipase; wherein the natural low eutectic solvent includes a hydrogen bond donor and a hydrogen bond acceptor, the hydrogen bond donor is proline, the hydrogen bond acceptor is lactic acid, the molar ratio of the hydrogen bond donor to the hydrogen bond acceptor is 1:1, the water content in the natural low eutectic solvent is 5%, and the mass of the natural low eutectic solvent relative to the mass of the soy milk is 50%. The extraction and separation process is: after mixing the soy milk and the natural low eutectic solvent, stir at a rate of 2500r / min for 5min, and then centrifuge at 10000rpm for 7min.

[0120] Step S4, heating the soy milk in step S3 to 85°C for 10 minutes to inactivate the enzyme, then passing through a 200-mesh sieve, adding 4.5% of the weight of white sugar to the sieve to prepare a semi-finished product.

[0121] Step S5, performing secondary homogenization, sterilization and cooling on the semi-finished product of step S4 to obtain soy milk; wherein the pressure of the homogenization is 40 MPa, the temperature is 75° C., and the time is 3 min; the temperature of the sterilization is 140° C., the time is 15 s, and the sterilization is completed and cooled to 30° C.

[0122] Example 1-2

[0123] The preparation methods of Example 1-2 are similar to those of Example 1-1, except that the molar ratio of the hydrogen bond donor to the hydrogen bond acceptor in the natural low eutectic solvent used in step S3 of Example 1-2 is 1:2, and the others are the same.

[0124] Examples 1-3

[0125] The preparation methods of Example 1-3 are similar to those of Example 1-1, except that the mass percentage of the natural low eutectic solvent used in step S3 of Example 1-3 relative to the mass of soy milk is 30%, and the rest are the same.

[0126] Examples 1-4

[0127] The preparation methods of Example 1-4 and Example 1-1 are similar, except that the temperature for the enzyme inactivation treatment in step S4 of Example 1-4 is 85° C. and the time is 30 min.

[0128] Examples 1-5

[0129] The preparation methods of Example 1-5 are similar to those of Example 1-1, except that the temperature for the enzyme inactivation treatment in step S4 of Example 1-5 is 90° C. and the time is 10 min.

[0130] The preparation methods of Example 1-6 are similar to those of Example 1-1, except that the temperature for the enzyme inactivation treatment in step S4 of Example 1-6 is 80° C. and the time is 30 min.

[0131] Examples 1-7

[0132] Step S1: Select clean non-genetically modified soybeans without impurities, peel them, and grind them through a 20-mesh sieve to obtain soybean powder for later use.

[0133] Step S2, mixing the soybean powder in step S1 with water at a mass volume ratio of 1kg:5L, and then preserving at 75°C for 10 minutes for leaching. After the leaching is completed, grinding and passing through a 120-mesh sieve to obtain a mixed liquid for standby use.

[0134] Step S3, adding the soy milk in step S2 to a natural low eutectic solvent to extract and separate lipase to obtain soy milk and lipase; wherein the natural low eutectic solvent includes a hydrogen bond donor and a hydrogen bond acceptor, the hydrogen bond donor is proline, the hydrogen bond acceptor is lactic acid, the molar ratio of the hydrogen bond donor to the hydrogen bond acceptor is 1:1.5, the water content in the natural low eutectic solvent is 3%, and the mass of the natural low eutectic solvent relative to the mass of the soy milk is 40%. The extraction and separation process is: after mixing the soy milk and the natural low eutectic solvent, stir at a rate of 1500r / min for 10min, and then centrifuge at 12000rpm for 5min.

[0135] Step S4, heating the soy milk in step S3 to 80°C for 30 minutes to inactivate the enzyme, then passing through a 150-mesh sieve, adding 3.5% of the weight of white sugar to the sieve to prepare a semi-finished product.

[0136] Step S5, performing secondary homogenization, sterilization and cooling on the semi-finished product of step S4 to obtain soy milk; wherein the pressure of the homogenization is 50 MPa, the temperature is 70° C., and the time is 3 min; the temperature of the sterilization is 130° C., the time is 20 s, and the sterilization is completed and cooled to 30° C.

[0137] Examples 1-8

[0138] Step S1, selecting clean non-genetically modified soybeans without impurities, peeling them, and crushing them through a 20-mesh sieve to obtain soybean powder for later use.

[0139] Step S2, mixing the soybean powder in step S1 with water at a mass volume ratio of 1kg:5L, and then preserving at 65°C for 60 minutes for leaching. After the leaching is completed, grinding and passing through a 200-mesh sieve to obtain a mixed liquid for standby use.

[0140] Step S3, adding the soy milk in step S2 to a natural low eutectic solvent to extract and separate lipase to obtain soy milk and lipase; wherein the natural low eutectic solvent includes a hydrogen bond donor and a hydrogen bond acceptor, the hydrogen bond donor is proline, the hydrogen bond acceptor is lactic acid, the molar ratio of the hydrogen bond donor to the hydrogen bond acceptor is 1:1, the water content in the natural low eutectic solvent is 4%, and the mass of the natural low eutectic solvent relative to the mass of the soy milk is 30%. The extraction and separation process is: after mixing the soy milk and the natural low eutectic solvent, stir at a rate of 2000r / min for 7min, and then centrifuge at 6000rpm for 10min.

[0141] Step S4, heating the soy milk in step S3 to 90°C for 30 minutes to inactivate the enzyme, then passing through a 200-mesh sieve, adding 5.5% of the weight of white sugar to the sieve to prepare a semi-finished product.

[0142] Step S5, performing secondary homogenization, sterilization and cooling on the semi-finished product of step S4 to obtain soy milk; wherein the pressure of the homogenization is 30 MPa, the temperature is 80° C., and the time is 3 min; the temperature of the sterilization is 150° C., the time is 8 s, and the product is cooled to 30° C. after the sterilization.

[0143] Comparative Example 1-1

[0144] The preparation methods of Comparative Example 1-1 and Example 1-1 are similar, except that in step S3 of Comparative Example 1-1, the same amount of water is used to replace the natural low eutectic solvent, and the rest are the same.

[0145] Comparative Example 1-2

[0146] The preparation methods of Comparative Example 1-2 and Example 1-4 are similar, except that in step S3 of Comparative Example 1-2, the same amount of water is used to replace the natural low eutectic solvent, and the rest are the same.

[0147] 2. Soymilk Quality Evaluation

[0148] 1. Sensory evaluation of soy milk

[0149] Anonymous evaluation was conducted among 30 people, focusing on the removal of bean flavor and beany smell of soy milk. The higher the score, the better the effect. The tasting results were statistically analyzed. The sensory evaluation results are shown in Table 1.

[0150] The protein content and soluble solid content of the soy milk prepared above were measured, and the results are shown in Table 1.

[0151] Table 1

[0152]

[0153] From the results in Table 1, it can be seen that the initial quality of the soy milk of Examples 1-1 to 1-8 is better than that of Comparative Examples 1-1 and 1-2. It can be seen that the comprehensive sensory score of the soy milk prepared by the preparation scheme provided by the present application is between 4.45 and 4.76, which is significantly higher than the comprehensive sensory score of Comparative Examples 1-1 and 1-2; the soy milk preparation method provided by the present application can effectively remove the undesirable flavors such as bean green smell and beany smell in soy milk, and improve the quality of soy milk.

[0154] From the comparison between comparative example 1-1 and comparative example 1-2, it can be seen that when the natural low eutectic solvent treatment is not used, the optimal enzyme inactivation process is to keep warm at 85°C for 30 minutes; from the comparison between Example 1-1 to Example 1-3 and comparative example 1-2, it can be seen that the soy milk preparation method provided in the present application can effectively shorten the enzyme inactivation time, and the enzyme inactivation effect is better, and the comprehensive sensory score of the soy milk is also higher.

[0155] 2. Sensory evaluation of soy milk shelf life

[0156] The sensory evaluation results of soy milk shelf life are shown in Table 2.

[0157] Table 2

[0158]

[0159] It should be noted that the "reduction in score" in Table 2 refers to the reduction in the score after 3 months relative to the initial score. The calculation formula is: (initial score - 3-month score) / initial score × 100%.

[0160] From the results in Table 2, it can be seen that with the extension of shelf life, the comprehensive sensory scores of each group decreased, and the higher the heating temperature and the longer the heating time during enzyme inactivation treatment, the greater the change in sensory quality of the group, that is, continuous high temperature and long-term treatment will accelerate the deterioration of sensory quality of soy milk during the shelf life.

[0161] Comparison of the results of Comparative Examples 1-1 and 1-2 shows that increasing the enzyme inactivation time from 85°C, 10 min to 85°C, 30 min can improve the initial sensory score of the soy milk product to a certain extent, but is not conducive to the shelf life stability of the product.

[0162] 3. Utilization of by-products from soy milk preparation

[0163] Example 2-1

[0164] Step S1, crushing soybean hulls and passing through an 80-mesh sieve to obtain soybean hull powder for later use; crushing bean dregs and passing through an 80-mesh sieve to obtain bean dregs powder for later use.

[0165] Step S2, mixing the soybean hull powder and dregs powder in step S1 in a mass ratio of 1:1 to obtain material A, and then adding material A to a natural low eutectic solvent to obtain a mixed material; wherein the natural low eutectic solvent includes a hydrogen bond donor and a hydrogen bond acceptor, the hydrogen bond donor is proline, the hydrogen bond acceptor is glycerol, the molar ratio of the hydrogen bond donor to the hydrogen bond acceptor is 1:1, the moisture content in the natural low eutectic solvent is 3%, and the mass of material A relative to the mass of the natural low eutectic solvent is 20%.

[0166] Step S3, stirring the mixed material in step S2 at a speed of 1500 r / min for 60 min.

[0167] Step S4: centrifuge the stirred mixture at 8000 rpm for 5 min, and take the supernatant obtained by the centrifugation.

[0168] Example 2-2

[0169] The preparation methods of Example 2-2 and Example 2-1 are similar, except that the molar ratio of the hydrogen bond donor to the hydrogen bond acceptor in the natural low eutectic solvent used in step S2 of Example 2-2 is 1:2, and the others are the same.

[0170] Example 2-3

[0171] The preparation methods of Example 2-3 and Example 2-1 are similar, except that in step S2 of Example 2-3, the same amount of lactic acid is used instead of glycerol as the hydrogen bond acceptor, and the rest are the same.

[0172] Embodiment 2-4

[0173] The preparation methods of Example 2-4 and Example 2-2 are similar, except that in step S2 of Example 2-4, the same amount of lactic acid is used instead of glycerol as the hydrogen bond acceptor, and the rest are the same.

[0174] Embodiment 2-5

[0175] The preparation methods of Example 2-5 are similar to those of Example 2-1, except that in step S2 of Example 2-5, the percentage of the mass of material A relative to the mass of the natural low eutectic solvent is 50%, and the rest are the same.

[0176] Embodiment 2-6

[0177] The preparation methods of Example 2-6 are similar to those of Example 2-1, except that the stirring time in step S3 of Example 2-6 is 10 min, and the others are the same.

[0178] Comparative Example 2-1

[0179] The preparation methods of Comparative Example 2-1 and Example 2-1 are similar, except that the same amount of phosphate buffer is used in step S2 of Comparative Example 2-1 to replace the natural low eutectic solvent, and the rest are the same. The pH value of the phosphate buffer (buffer system composed of sodium dihydrogen phosphate and dipotassium hydrogen phosphate) is 7.0, and the molar concentration is 50 mM.

[0180] Comparative Example 2-2

[0181] The preparation methods of Comparative Example 2-2 and Example 2-1 are similar, except that in step S2 of Comparative Example 2-2, the same amount of deionized water is used to replace the natural low eutectic solvent, and the rest are the same.

[0182] 4. Determination of lipase hydrolysis activity

[0183] The p-NP method was used to determine the hydrolysis activity of lipase. The specific determination method is:

[0184] 80μL of 0.1 mol / L pH = 7.0 phosphate buffer and 10μL of 10mmol / L C8 solution were added to a 96-well plate, preheated at 40℃ for 10 min, 10μL of the test solution was added, and after reacting for 5 min, 100μL of 1% SDS solution was used to terminate the reaction, and the absorbance was measured at 405 nm. The release amount of the product pNP was obtained on the p-NP standard curve according to A405 nm and the enzyme activity was calculated. The amount of enzyme required for the substrate to be hydrolyzed to generate 1μmol p-NP per minute under certain conditions was an enzyme activity unit, represented by U. A control experiment was carried out under the same conditions, in which the specific operation of the lipase stability test was to store the enzyme solution at 4℃ for 1 week to 4 weeks, and measure the enzyme activity once a week. The results were expressed as relative enzyme activity, where relative enzyme activity = measured enzyme activity / initial enzyme activity*100%. The results are shown in Table 3.

[0185] Table 3

[0186]

[0187] From the results in Table 3, it can be seen that the initial activity and stability of the lipase extracted by the natural low eutectic solvent in the present application are significantly better than the initial activity and stability of the lipase extracted by the phosphate buffer method and the traditional water extraction method. The reason for this may be that the hydrogen bonding effect of the natural low eutectic solvent plays a protective role in stabilizing the structure of the lipase.

[0188] From the comparison of the results of Examples 2-1 to 2-4 and Comparative Examples 2-1 to 2-2 in Table 3, it can be seen that there are differences in the initial activity and stability of the lipase extracted by different types of solvents. In general, the natural low eutectic solvent extraction method > phosphate buffer method > traditional water extraction method; among them, the best method is the group with a proline and glycerol molar ratio of 1:2. The lipase extracted by this system has the largest initial enzyme activity and the highest stability. After storage at 4°C for 4 weeks, the residual enzyme activity of the lipase extracted by this method is as high as 85%, and the residual enzyme activity of the lipase extracted by other natural low eutectic solvents is maintained above 80%.

[0189] The residual enzyme activity of the lipase extracted by the two traditional methods in Comparative Examples 2-1 and 2-2 gradually decreased with the extension of storage time. The residual enzyme activity of the lipase extracted by the phosphate buffer method was only 50% of the initial enzyme activity after 2 weeks, and the enzyme activity was completely lost in the 4th week; and the residual enzyme activity of the lipase extracted by the water extraction method was even 50% after 1 week, and no enzyme activity was detected after 2 weeks.

[0190] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0191] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A method for preparing soy milk, characterized in that: The steps include: The soybean powder is mixed with water, and then extracted, ground and sieved in sequence to prepare a mixed liquid; The mixed liquid is mixed with a solvent and then extracted and separated to prepare soybean milk and lipase; the solvent comprises a hydrogen bond donor and a hydrogen bond acceptor, the hydrogen bond donor comprises proline, and the hydrogen bond acceptor comprises lactic acid; The soymilk is subjected to enzyme inactivation and sieving in sequence, and auxiliary materials are added to the sieve to prepare a semi-finished product; The semi-finished product is subjected to homogenization and sterilization treatments in sequence to prepare the soy milk.

2. The preparation method according to claim 1, characterized in that The molar ratio of the hydrogen bond donor to the hydrogen bond acceptor in the solvent is 1:(1-2); and / or The solvent further comprises water, and the mass proportion of the water in the solvent is 3%-5%; and / or The mass percentage of the solvent relative to the mass percentage of the mixed liquid is 30%-50%; and / or The extraction and separation process comprises: stirring the mixed material and the solvent for 5 minutes to 10 minutes, and then centrifuging at 6000 rpm to 12000 rpm for 5 minutes to 10 minutes.

3. The preparation method according to claim 1, characterized in that: The mass volume ratio of the soybean powder to water is 1 kg: (4-8) L; and / or The leaching temperature is 65°C-75°C and the leaching time is 10min-60min; and / or The mesh number of the sieve used for the grinding and screening is 120 meshes-200 meshes.

4. The preparation method according to claim 1, characterized in that: The temperature of the enzyme inactivation treatment is 80°C-90°C and the time is 10min-30min; and / or The mesh size of the sieve used in the sieving process is 150-200 mesh; and / or The auxiliary materials include white sugar; and / or The mass percentage of the auxiliary material relative to the mass of the undersize obtained by the screening process is 3.5%-5.5%.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The homogenization treatment is performed at a pressure of 30MPa-50MPa, a temperature of 70°C-80°C, a time of 2min-5min, and a number of times of two times; and / or The sterilization treatment is carried out at a temperature of 130° C. to 150° C. and for a time of 8 s to 20 s.

6. A soy milk, characterized in that: Prepared by the preparation method according to any one of claims 1 to 5; Optionally, the protein content in the soy milk is ≥2.1wt%, and the soluble solid content is 10wt%-15wt%.

7. A method for utilizing by-products of soybean milk preparation, characterized in that: The utilization method comprises the following steps: The byproduct of soy milk preparation is mixed with a solvent to prepare a mixed material; the byproduct of soy milk preparation includes soybean hull powder and soybean dregs powder; the solvent includes a hydrogen bond donor and a hydrogen bond acceptor, the hydrogen bond donor includes proline, and the hydrogen bond acceptor includes lactic acid and / or glycerol; The mixed material is sequentially subjected to stirring treatment and centrifugal treatment, and the supernatant obtained from the centrifugal treatment is taken.

8. The utilization method according to claim 7, characterized in that: The molar ratio of the hydrogen bond donor to the hydrogen bond acceptor in the solvent is 1:(1-2); and / or The solvent further comprises water, and the mass proportion of the water in the solvent is 3%-5%; and / or The mass percentage of the soymilk preparation by-product relative to the mass percentage of the solvent is 20%-50%; and / or The mass ratio of the soybean hull powder to the soybean dregs powder in the soymilk preparation by-product is 1:(1-3).

9. The utilization method according to claim 7, characterized in that: The stirring time is 10 min-60 min, and the rotation speed is 1500 r / min-2500 r / min; and / or The rotation speed of the centrifugal treatment is 6000r / min-12000r / min, and the time is 5min-10min.

10. A lipase, characterized in that The soybean milk is prepared by the method for utilizing by-products of soybean milk preparation as described in any one of claims 7 to 9.

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