Method for obtaining protein from a mixture of natural substances in soybeans or soy milk

Abstract

A method for obtaining protein (17) from soybean milk (12), comprising i. providing soybean milk (12); ii. concentrating the soybean milk (12) with an increased dry matter content (21); ii. adding a water-soluble organic solvent (15) to the soybean milk of step ii to form an organic aqueous suspension, wherein the solubility equilibrium is shifted by the addition of the organic solvent and displacement extraction occurs (22), wherein the volume of the organic solvent (15) added in step iii is selected so that the organic solvent content of the organic aqueous suspension after step iii is at least 15% by volume, iv. adjusting (13) the suspension to a pH value less than pH=7 to form at least one protein phase (17); and v. separating (16) a protein phase (17) having a residual oil content of less than 5% by weight from the suspension based on the dry matter content of the protein phase (17). And a method for obtaining protein (17) from a natural substance mixture of soybean (1).

Description

[0001] The present invention relates to a method for obtaining protein from a natural substance mixture in soybeans or soy milk. Compared with conventional retail products, soy milk is not a composition that is fully diluted with water, but a viscous product that is directly separated from soybeans by a centrifuge. Such soy milk is also often referred to as "soy base" or "soy juice" in technical literature. Such soy milk can also be an intermediate product of a method using a natural substance mixture from soybeans.

[0002] It is known to further process the okara formed from soy plant parts such as soybeans (husked or unhusked) or soy flakes. From the separated soy milk a protein phase can be obtained.

[0003] The methods known so far for separating proteins from soy milk allow recovery of about 80% by weight of the proteins contained in the soy milk. However, oil and oil-associated substances such as lipoxygenase are transferred to the proteins. The above enzymes react with the oil present and form unfavorable tastes in the protein phase. In addition to lipase, soy milk may contain, among other things, trypsin inhibitors as components, which interfere with the absorption of proteins in the body. Furthermore, a minimum oil content is required to prevent the end product from becoming rancid.

[0004] WO 2007 / 113 176 A2 discloses processing soybeans to produce soy milk and native protein. In this process, no reduction in oil content is performed.

[0005] EP 1 905 312 A1 likewise proposes separating soybeans into soymilk and protein fractions. The oil is removed from the protein by extraction with ether instead of hexane.

[0006] EP 2 717 711 B1, paragraph 0010, starts from an aqueous protein dispersion which is treated by partial displacement extraction in an alkaline environment with the addition of an alcoholic solvent in order to bring oily accompanying substances such as lecithin into solution. This allows the dissolved or dispersed protein to be separated from the pod components.

[0007] DE 10 2013 114 698 A1 finally discloses a method for obtaining protein from legumes such as soybeans. The beans are comminuted as a whole and processed into a slurry. Then, finally, after a pH shift to pH>9 using alcohol, they are separated to remove the husks. Finally, at an acidic pH, precipitation and separation of various fractions, including a protein fraction and an oil fraction, are carried out.

[0008] It is an object of the present invention to reduce the oil content of the protein phase obtained from the soy component in such a way that no undesirable changes in taste occur.

[0009] The method according to the present invention involves recovering protein from soy milk, which comprises

[0010] i. Provide soy milk;

[0011] ii. adding aqueous alcohol in a concentration of less than 80% by volume to the soy milk, thereby forming an organic aqueous suspension, that is, by adding aqueous alcohol, a shift in solubility equilibrium occurs and displacement extraction is performed, wherein the volume of aqueous alcohol is selected in such a way that the organic solvent content of the organic aqueous suspension after step ii is at least 15% by volume and the dry matter content of the suspension is at least 5% (preferably at least 9%);

[0012] iii. Separating the oil phase or oil from the suspension;

[0013] iv. coagulating the protein to form at least one protein phase by adjusting the suspension to a pH value of less than pH = 7 or by adding a protein coagulant-forming salt;

[0014] and

[0015] v. separating a protein phase having a residual oil content of less than 5% by weight, in particular a residual oil content of less than 3%, particularly preferably a residual oil content of less than 1%, based on the dry matter content of the protein phase in the suspension.

[0016] The protein phase had minimal flavor change and little residual oil.

[0017] The provision of soy milk in step i can be carried out by obtaining soy milk from a soybean natural substance mixture, wherein the natural substance mixture is first pulverized and processed into a flowable alkaline slurry by pH adjustment and addition of a polar solvent, in particular water, which contains, in addition to lipids, proteins, lecithin and solids, wherein the processing of the slurry is carried out while forming two separate fractions in the form of okara and soy milk.

[0018] The slurry contains all the essential components of soybeans, including oil. If the soybeans are shelled, the slurry contains less fiber. Okara is a "solid cake" with insoluble components, and soy milk has a large amount of protein and dissolved, dispersed substances.

[0019] In addition, the provision of soy milk may include concentrated, preferably thickened soy milk with increased dry matter content, so that the provided soy milk may have a dry matter content of preferably at least 12 wt%, preferably at least 15 wt%. This corresponds to relatively viscous soy milk.

[0020] Concentration to a dry matter content of at least 15% has been shown to be a particularly effective way of releasing the oil component from the protein structure under defined conditions of pH and temperature and alcohol concentration. In a known manner, proteins contain primary, secondary, tertiary and quaternary structures which usually retain the oil component. Opening up the structure under specific conditions allows the oil to be separated particularly effectively.

[0021] Further preparation for optimal protein structure by concentration and subsequent oil separation by displacement extraction with EtOH can be achieved more successfully. The addition of ethanol naturally reduces the dry matter content again, preferably to a dry matter content of at least 8%.

[0022] During the concentration, the inner surface of the oil droplets can optionally also be changed and thereby allow for better agglomeration. If the oil droplets are large enough, they can be particularly well agglomerated into a continuous phase in a centrifugal field and thus separated.

[0023] Particularly preferably, the concentration can be effected in such a way that the amount of water removed corresponds approximately to the amount of aqueous alcohol added. Thus, despite the addition of a relatively large amount of diluent alcohol to reach an alcohol content of at least 15% by volume, the dry matter value is at least 8%.

[0024] It is recommended that the concentration of added alcohol be less than or equal to 80% by volume. Higher concentrations of alcohol denature proteins. On the other hand, alcohol below 50% by volume produces poor results in displacement extraction due to the high dilution factor.

[0025] In the following, further processing of soy milk is explained.

[0026] According to the present invention, the organic solvent is added as a diluted alcohol, preferably with an alcohol content of at least 30% by volume, preferably between 50-80%.

[0027] At 50-80% by volume, the recovery of the alcohol can advantageously be carried out under vacuum.

[0028] Preferably, the organic water-soluble solvent is an aliphatic alcohol, in particular an aliphatic alcohol having a chain length of less than six carbon atoms and / or isopropanol.

[0029] The pH adjustment in step iv may preferably be such that the pH value is greater than pH=3.5, preferably between pH=3.8 and 6.0, in particular between pH=4.2 and 4.7.

[0030] The concentration can be carried out by reducing the water content of the soy milk, wherein the weight is reduced by at least 20% by weight, preferably by at least 40% by weight, to a dry matter content of at least 12% by weight, particularly preferably at least 15% by weight.

[0031] After step iii, the content of the organic water-soluble solvent in the suspension can be greater than 15% by volume, preferably 25-45% by volume. Through this, a clear oil phase can be separated. At lower concentrations, the separation of the oil phase is carried out in the form of a cream, but this is associated with a loss of protein product.

[0032] If in step i, the soy milk is prepared from an oil-flowable slurry containing okara, it is advantageous if the flowable alkaline slurry or the soy milk prepared therefrom in step i has a pH value greater than pH=8, in particular between pH=8.2 and 9.8. However, in another variant of the invention, it is also possible to start from an acidic soy milk with a pH value of 6.7 without prior pH adjustment. In the case of such soy milk, it is also recommended to adjust the pH value for precipitation after the addition of ethanol, in particular within the preferred range of pH=3.8 to 6.0.

[0033] After the addition of the water-soluble organic solvent in step iii, in particular directly after the addition of the water-soluble organic solvent, a series of operations (absorption) of at least one kneading (malaxieren) (preferably with a stirring rate of less than 100 rpm) can be carried out. The series of operations can particularly preferably further include at least one intensive stirring, preferably with a stirring rate of more than 500 rpm. The order within the series of operations can also be reversed, i.e. first intensive stirring followed by kneading, or multiple series of intensive stirring operations, followed by a single kneading, or a series of multiple kneading operations, followed by a single intensive stirring. This series of operations achieves particularly complete oil separation, because the oil droplets are better separated from the protein molecules, then agglomerated by slow stirring to form larger oil droplets and ultimately an oil phase.

[0034] Regardless of the repetition of the series of operations or whether such a series of operations is actually carried out, kneading should always be carried out and preferably the series of operations is ended by said kneading.

[0035] The kneading can preferably be carried out at a stirring rate of less than 50 rpm, preferably between 10 and 30 rpm. For particularly optimized oil agglomeration, the kneading can also be carried out at 20 to 70° C., particularly preferably at 40 to 70° C.

[0036] Preferably, kneading may be carried out within a time interval between 5 and 30 minutes. Longer kneading has no further beneficial effect on the formation of the oil phase.

[0037] On the other hand, intensive stirring may be performed at a stirring rate of more than 1000 rpm, in particular between 1000 and 12000 rpm.

[0038] The above series of operations can be repeated multiple times, in particular at least 3 times, to achieve additional optimization of separating oil from the suspension. However, the above series of operations should ideally include at least one kneading.

[0039] Furthermore, the oil phase can be separated from the suspension before step iv, and preferably after the series of at least one kneading and at least one intensive stirring operation, in particular centrifugal separation. Due to the high viscosity of the suspension, it is advantageous to use a decanter, in particular in the design of a non-perforated sheathed screw centrifuge, or a separator.

[0040] The centrifugal separation can be particularly optimally carried out at a temperature of more than 20° C., preferably between 35 and 80° C., particularly preferably between 35 and 45° C. In particular, the above ranges provide optimum processing times and technical expenditure (Ex-operation).

[0041] Prior to step iv, and preferably after centrifugal separation of the oil phase, a dealcoholation can be carried out, preferably by evaporation of the alcohol. Recovery of the organic solvent previously added in the form of alcohol can be carried out here.

[0042] After pH adjustment in step iv, the suspension can be transferred to a container for precipitation of the protein.

[0043] The precipitation can be carried out at a temperature above 20° C., preferably between 50 and 80° C., particularly preferably between 60 and 75° C., and also preferably within a period of between 5 and 20 minutes.

[0044] The separation in step v may be a centrifugal separation, and is preferably carried out by a decanter, in particular by a non-porous jacketed screw centrifuge.

[0045] The centrifugal separation with a separation range, the so-called cut-off value, between 1.0 and 100 μm can be carried out in a centrifuge or a decanter.

[0046] After the protein is separated, it can be dried.

[0047] The protein phase separated in step v may have less than 0.5 wt% lecithin.

[0048] Steps i to iii, and preferably also the provision of the alkaline slurry, may be carried out at a temperature ranging between 35°C and a maximum of 85°C.

[0049] The polar solvent used to form the flowable slurry before step i can preferably be water, wherein the volume of the aqueous polar solvent is selected in such a way that the dilution factor is set to be greater than 0.2, preferably at least 2.0, based on the concentrated slurry. The crude suspension usually has a dry matter content of about 8-9% dry matter, which is then concentrated and diluted again with the polar solvent. It should then have a dry matter content of not less than 5% again, preferably between 7% and 13%, particularly preferably at least 8%, in particular 9% (+ / -1). However, a higher dry matter content is not disadvantageous.

[0050] For dry matter contents above 5%, processing at a temperature of 70° C. is particularly recommended, while for dry matter contents of at least 8%, processing at temperatures below 70° C. is also possible, which is advantageous from a process engineering point of view.

[0051] The natural substance mixture can be comminuted by gentle wet grinding of the product.

[0052] The separation in step v may be started within 60 minutes, particularly within 30 minutes, after performing step iv to avoid side reactions.

[0053] In particular, the protein phase is obtained without adding hexane, so there are no health concerns when the final product is used as feed or food.

[0054] Obtaining and processing oils and fats according to the guidelines of organic farming specifically allows mechanical production steps. With few exceptions, the use of chemical auxiliaries is prohibited. These include extraction solvents such as hexane and ether.

[0055] The pH value is adjusted in step iv by adding an organic or inorganic acid, for example by fruit acid.

[0056] A preferred embodiment of the method comprises the following steps:

[0057] i. Providing soy milk, preferably with a pH greater than pH = 7.2;

[0058] ii. Concentrating soy milk to increase the dry matter content;

[0059] iii. adding a short-chain alcohol having 1 to 5 carbon atoms and forming an aqueous alcohol suspension, in particular adding ethanol and / or isopropanol, wherein the alcohol content of the aqueous alcohol suspension after step iii is at least 15% by volume, preferably at least 20% by volume,

[0060] iii.i A series of operations consisting of at least one kneading operation with a stirring rate of less than 100 rpm;

[0061] iii.ii separation of the oil from the suspension, in particular a first centrifugal separation, to form a substantially oil-free suspension having an oil content of less than 5% by weight, preferably less than 3% by weight, in the dry material;

[0062] iii.iii optionally reducing the alcohol content, preferably by distillation, particularly preferably with recovery of alcohol;

[0063] iv. adjusting the suspension to a pH value less than pH = 7, preferably to a pH value between pH = 3.5 and pH = 6; thereby forming at least one protein phase and at least one liquid phase;

[0064] iv.i optionally precipitating the protein phase as a solid phase;

[0065] v. separation of a protein phase from the suspension, in particular a second centrifugal separation, the protein phase having a residual oil content of less than 5% by weight, preferably between 1 and 3% by weight, based on the dry matter of the protein phase, and

[0066] vi. Drying the protein phase into protein

[0067] Furthermore, according to the invention is a method for obtaining protein from a soy natural substance mixture, wherein the natural substance mixture is first comminuted and processed by pH adjustment in the alkaline range and addition of a polar solvent to form a flowable alkaline slurry which contains, in addition to polar lipids, proteins, lecithin and solids, wherein the method has the following further steps:

[0068] A treating the slurry to form two separate fractions in the form of okara and soy milk, and

[0069] B. Processing soy milk into a protein phase according to the method of the present invention.

[0070] Other advantageous designs of the above method are described below. The pH adjustment for producing the flowable alkaline slurry can preferably be carried out by adding an alkaline solution such as NaOH or NaHCO3 solution.

[0071] In addition to lipids, this slurry also contains protein, lecithin and solids.

[0072] During the separation into soy milk and okara, most of the protein in the slurry is separated from the soy milk in a dissolved and / or dispersed manner. In an additional okara washing process, the protein yield in the soy milk can be increased to significantly more than 70%.

[0073] In this case, some proteins remain in the okara and can be obtained separately from the further processing of the soy milk.

[0074] Steps i) to iii) and preferably also the provision of the alkaline slurry can preferably be carried out in a temperature range up to a maximum of 85° C. In particular, at least the provision of the alkaline slurry can be carried out at below 15° C. so as not to adversely affect the taste changes of the final protein product or other by-products such as okara.

[0075] Usually, the soy milk is already boiled or heated when it is provided in order to neutralize the trypsin inhibitors, since otherwise they interfere with the digestion when the protein is consumed. This can also be optionally performed during the provision of step i).

[0076] The polar solvent used to form the flowable slurry is preferably water, wherein the volume of water used for the beans is selected so as to adjust to a dilution factor of more than 2.0, preferably at least 3.0, in particular between 3.5 and 7.5. Preferably, the polar solvent used to form the slurry in the process can be recovered, for example by means of an evaporator. This allows, for example, after separation of the protein phase in step v, the polar solvent used to form the flowable slurry and the alcohol used to be recovered by fractionation and introduced into the various stages of the process. This also reduces the waste disposal costs, among other things.

[0077] The comminution of the natural substance mixture can advantageously and gently on the product be carried out by wet grinding.

[0078] The process has the particular advantage that the addition of hexane and ether to obtain the protein phase can be completely dispensed with. This eliminates the need for costly and labor-intensive additional steps to remove these substances from the product. Hexane is harmful to health and is therefore undesirable in products for the feed and food industry.

[0079] Furthermore, according to the invention is a method for obtaining protein from soy milk having a residual oil content of more than 3% in dry matter. Soy milk generally always contains a residual oil content of much more than 3% in dry matter, mostly 20% oil / dry matter. Ideally, soy milk can be obtained according to the above method, because such soy milk is particularly rich in dry matter and protein. However, soy milk which is not obtained from a flowable alkaline aqueous slurry can also be processed according to the method according to the invention and separated according to step i of the above method.

[0080] It can be understood that all variants, especially the variants described as advantageous in the above steps, can be applied to the above method for obtaining protein from a soybean natural substance mixture, and can also be advantageously applied to the above method for obtaining protein from soy milk.

[0081] Also according to the invention is a soy protein meal having an oil content of up to 5% oil in the dry matter and a protein content of at least 70% protein in the dry matter, wherein the soy protein meal is completely free of hexane. Since no hexane is used in the above process, no hexane is present in the product (even in the ppm range). To date, no such product is known with such an oil content.

[0082] Further advantages, features and details of the invention are given in the following description, in which several exemplary embodiments of the invention are explained in more detail with reference to the accompanying drawings. A person skilled in the art will advantageously also consider the features disclosed in the drawings, descriptions and claims individually and combine them to form useful further combinations. The diagram is as follows:

[0083] Figure 1 a process diagram showing various preparation steps for providing soy milk during the production of protein from soybeans; and

[0084] Figure 2 A process diagram for producing protein powder from soy milk as a variant of the method according to the invention is shown.

[0085] Proteins mostly have a primary, secondary, tertiary and possibly quaternary structure. The structural composition depends on the contents, such as the oil content, the type of oil (polarity), the type and concentration of other ingredients in the suspension, the dilution factor, the solvent polarity, the pH value, the temperature and many other factors. The structural composition determines the extent to which the various contents, such as oil and other non-polar and low-polar substances, can be released. If the protein is present in a more compact structure, it is more difficult to release the oil from the protein structure. Therefore, depending on the plant variety, the conditions for protein production can vary greatly.

[0086] The following method describes the optimal extraction of protein from Glycine max, in particular soybeans. Alternatively, the method can also start with soy milk as an intermediate product.

[0087] In an optional first step, a natural substance mixture from soybeans 1 is provided. In the present invention, a natural substance mixture from soybeans is understood to be soybeans in the hulled or unhulled state, but also so-called soya flakes. When a granular component is present, for example as a heap or as bulk material, it is referred to as a substance mixture.

[0088] Such a substance mixture from soybean 1 may consist, for example, of 38% by weight of proteins, 18% by weight of fats, 15% by weight of insoluble hydrocarbons, 15% by weight of soluble hydrocarbons and 14% by weight of other contents.

[0089] The material mixture of soybeans can first be stored in a storage tank 2 and then directed to a cleaning system 3 that removes dirt from the soybeans or soybean flakes and separates stones and trimmings. This can be done, for example, by washing and screening the material mixture.

[0090] In an optional second step, a softening 4 of the natural substance mixture can be carried out. For this purpose, water 5, preferably water at a temperature below 20° C., preferably below 15° C., can be added to the substance mixture. This reduces the enzyme activity, in particular the lipoxygenase activity.

[0091] The softening 4 is preferably carried out in at least 3 hours, preferably 4 to 10 hours. It is recommended to preferably use dehulled soybeans or soybean flakes for the softening of the substance mixture. These only require about 3.5 to 4.5 hours to soften. Unhulled soybeans require longer time to soften. The softening of soybeans allows better conditions in the subsequent grinding process. The grinding of softened plant components is usually described as wet grinding.

[0092] As the amount of water 5 used, a weight ratio of at least 2:1 (water to soybeans) or higher, such as 3:1, based on the amount of soybeans is recommended.

[0093] In a third step, comminution 6 of the soy component of the substance mixture 1 is carried out. This can preferably be carried out as wet grinding in the form of cold grinding, warm grinding or hot grinding.

[0094] Cold grinding is preferably carried out at a temperature below 15° C. This reduces the activity of the enzyme, but leads to a decrease in yield.

[0095] Warm grinding is preferably carried out at a temperature between 30-50°C, preferably at about 40°C. As a result, the taste changes as a bean-like taste in the subsequently produced soy milk due to increased enzyme activity. This may be desirable for some consumer groups. At the same time, higher temperatures can increase the yield.

[0096] Hot grinding is carried out at a temperature above 80°C. This inactivates the enzymes. In this variant, hot water, preferably above 95°C, is added to the soy component and preferably kept for several minutes, for example at least 4 minutes. Compared with warm grinding, this variant also reduces the yield.

[0097] The comminution 6 by grinding can optionally and preferably be carried out in at least two stages. The first stage can be pre-grinding in a disc mill.

[0098] If the predetermined average particle size is reached, further fine grinding can be carried out in a colloid mill. In this process, the cells are opened and the yield is thereby increased.

[0099] Before, during or after comminution, the pH value 7 of the mixture or the comminuted mixture can be increased in a fourth step. In this process, the pH value is increased for reasons of yield optimization. A higher pH value allows, in particular, an improvement in the solubility of proteins in water. To increase the pH value, preferably an alkaline solution is added, for example a NaOH solution or a buffer solution 8, for example a sodium bicarbonate solution.

[0100] The result of the above steps is a flowable alkaline slurry 9, which is at least fractionated into okara 11 and soy milk 12 in the fifth step. Further advantageous for the yield of oil-free protein from soy milk is the portion of water addition 5 in the preparation of the flowable slurry 9. Therefore, the experimental results show that before the slurry is fractionated into okara and soy milk, when the dilution factor is changed from 2 to 3 with the addition of water, up to 10% more protein can be obtained as an oil-free product from soy milk. The 10% more protein refers to the total weight of protein in the substance mixture as the starting material. A further increase in the amount of water brings a further increase in the yield, but from a water amount of more than 7 to 1, it becomes disadvantageous for the process technology.

[0101] At least one first decanter, preferably a non-perforated jacketed screw centrifuge, is used for the separation 10 into the two fractions. The first decanter preferably has a horizontal axis or an axis of rotation that is inclined by up to 25° to the horizontal. The feeding of the slurry takes place axially, the discharge of the solids, i.e., the okara, and the discharge of the soy milk take place radially. The discharge of the solids can take place in the first end region of the decanter, and the discharge of the soy milk in the second end region of the decanter.

[0102] In addition to the further processing of the soy milk 12 according to the invention, the okara 11 can also be further processed in a single-stage or multi-stage process. In the single-stage process, as described above, the okara 11 is separated from the soy milk in a decanter and discharged from the decanter. Here, a screw pump can be used for transportation. Under this process, a protein yield of more than 70% can be achieved for this discharge. Alternatively, the separated okara 11 can also be slurried in water again and post-processed with a second decanter. The separated soy water can be used for softening and returned to the process. Under this variant of the method, the protein yield can be as high as about 80%.

[0103] The slurry 9 supplied to the first decanter feed may have an insoluble component content of 25-30% by volume. The temperature of the supplied slurry may preferably be greater than 75°C.

[0104] The dry matter content of the soy milk 12 at the outlet of the first decanter is preferably >5% m / m, preferably at least 8%, ideally 8 to 10.5% m / m.

[0105] Optionally, in an optional sixth step, not shown in detail, the soy milk can be treated by ultra-high temperature heating and / or deodorization. In the process, hot steam can be introduced into the soy milk to inactivate enzyme activities. The product can be heated to more than 100° C., preferably between 120-140° C. Through this, inactivation of trypsin inhibitors can be achieved. As described, direct heating by steam introduction is preferred here. The temperature is maintained for less than 60 seconds, preferably less than 10 seconds. Thereafter, the soy milk can be cooled again. This can preferably be directly cooled by a vacuum cooling system without the need for an additional coolant in the form of expansion cooling (Entspannungskühlung).

[0106] Figure 2 An embodiment variant according to the invention for processing soy milk is shown in FIG.

[0107] In the seventh step (step ii), the amount of soy milk is then concentrated 21, for example by evaporating a greater portion of water from the soy milk 12, so that the weight of the soy milk is reduced by at least 10% by weight, preferably by at least 40% by weight. However, there are also soy milks that are already present as raw materials with 12% or 12.5% ​​dry matter. This does not need to be concentrated that much. In general, it is recommended to have a product with a dry matter content of at least 12%, preferably 15%, before ethanol extraction.

[0108] This step is preferred for the subsequent phase inversion. Surprisingly, it has been shown that a concentration of the soymilk amount, in particular a dry matter content of 15% by weight, is particularly advantageous in order to optimize the process solely from a process technology point of view and to release the oil in an optimal manner.

[0109] After the concentration 21 in the seventh step, an organic solvent 15 is added in the eighth step within the framework of a displacement extraction 22. Alcohols having 1 to 5 carbon atoms are particularly preferably recommended as organic solvents 15, but ethanol and / or isopropanol are particularly preferred. It has been shown that with the addition of a diluted alcohol solvent, a better separation of proteins with a very low oil content is possible than, for example, with concentrated alcohols. Therefore, the addition of the solvent in diluted form can therefore preferably be carried out with a solvent content of greater than 30% by volume, preferably between 50 and 96%, particularly preferably between 55 and 80%. For example, it has been found that for the use of ethanol, the ideal alcohol dilution is 60% by volume (+ / -5%). During the addition of the solvent, mixing of the suspension can be carried out to achieve rapid dispersion and uniform distribution in the suspension.

[0110] The volume and concentration of the solvent, especially the alcohol, should be such that the content of the organic water-soluble solvent 15 in the suspension after step iii is greater than 15% by volume, preferably between 25 and 45% by volume.

[0111] For example, for the use of ethanol, it has been found that the ideal alcohol concentration in soy milk is 25% by volume (+ / - 5%).

[0112] For comparison purposes, a pure water treatment in the acidic pH range (pH=5) was carried out with the same soy milk 12 without the addition of ethanol. This resulted in a protein product with an oil content of 5.1 wt.-% after separation of the solid phase.

[0113] After the addition of the organic water-soluble solvent in the eighth step, a series of operations 22 consisting of kneading 24 and vigorous stirring 25 is carried out in the ninth step. Vigorous stirring 25 can particularly include vigorous mixing. The order can be selected arbitrarily. In particular, it is also possible to first carry out vigorous stirring and then kneading. Advantageously, at least one kneading step 26 is carried out directly before separation 27. However, before this kneading step 26, as described above, a series of operations consisting of another kneading 24 and vigorous stirring 25 can also be repeated multiple times in any order.

[0114] The intensive stirring 25 defined according to the present invention is carried out at a speed of more than 500 rpm, particularly preferably 1000-500 rpm.

[0115] In contrast, the kneading 24 , 26 according to the present invention is carried out at a stirring rate of less than 100 rpm, preferably less than 50 rpm, particularly preferably between 10 and 30 rpm.

[0116] During the intense stirring, shear forces occur due to the increased stirring rate, which allows for a better separation of the oil from the protein structure. In the process, the oil droplets are actually squeezed out of the protein-containing material.

[0117] In contrast, kneading allows the oil droplets in the suspension to coalesce into larger droplets until an oil layer due to the extremely low stirring rate.

[0118] exist Figure 1 In FIG. 2 , a one-time series of operations consisting of kneading 24, vigorous stirring 25 and then kneading 26 is shown. This series of operations of steps 24 and 25 is shown in FIG. Figure 2 The above is described as step 23, and may be executed 0 to n times, wherein n represents the number of executions in any order.

[0119] The temperature during kneading 24, 26 is preferably 40-70°C, and the time interval between kneading 24, 26 is also preferably 5-30 minutes.

[0120] In the tenth step, separation 27 of the oil phase 28 is performed to form a substantially oil-free suspension 31. If the suspension after the eighth step contains more than 20% by volume of a solvent, in particular an alcohol, a relatively clear oil phase 28 can therefore be separated in this step. At a concentration of between 15 and 20% by volume of the solvent, the separated oil phase 28 has the consistency of a cream.

[0121] The separation can be preferably carried out at a temperature greater than 40° C., preferably between 50-80° C., particularly preferably between 60-75° C., for example at 70° C. This makes the separation of the oil more convenient.

[0122] Optionally, dealcoholation 29 can be carried out in step 11. This dealcoholation can be carried out by evaporation or distillation of the alcohol. In particular, it is possible to at least partially recover the alcohol used in step 8. However, dealcoholation is not absolutely necessary. The protein yield without this step is comparable.

[0123] A final pH adjustment of the alkaline suspension is then carried out in step 12 13, if not already carried out before step 10. For acid precipitation, the pH adjustment should be able to be pushed into the acidic range, ie below pH=7.

[0124] The pH value is preferably adjusted using a food-grade acid 14. Fruit acids are preferred, particularly citric acid. However, inorganic acids such as HCl can also be used. The pH value should preferably be at a pH value greater than pH=3.5, preferably between pH=3.8 and 6.0, in particular between pH=4.2 and 4.7, because the configuration of the protein structure in this range allows optimal oil separation and the protein has a structure that facilitates further processing, such as centrifugal separation and drying.

[0125] The acid concentration is preferably 5-50% by volume.

[0126] During the acid addition, mixing of the suspension may be performed to achieve rapid adjustment of the pH value and uniform distribution in the suspension.

[0127] Alternatively, protein coagulant-forming salts such as calcium sulfate, calcium chloride, magnesium chloride and / or calcium saccharate may be used instead of acid for pH adjustment.

[0128] The concentration of the added salt is preferably at least 0.15% by mass, particularly preferably 0.2% by mass to 2.5% by mass, based on the total mass of the soymilk.

[0129] Following the addition of the acid or coagulation salt, in step 13, the protein can first be precipitated by gravity 30. For this purpose, the suspension is transferred to a sedimentation tank. Due to the change in pH, the protein can be precipitated out of the suspension. This process can preferably last for 5-20 minutes. The optimal precipitation of the particulate protein can be carried out at a temperature above 40° C., preferably between 50-80° C., particularly preferably between 60-75° C.

[0130] After the precipitation, a separation 16 is carried out in a fourteenth step into a protein fraction 17 and a liquid fraction 18. This can be carried out in a centrifuge, in particular in a separator or in a filter device. Optionally, a separation of an oil phase 19 or an oil fraction as a further valuable product can also be carried out here, but the oil component can also remain in the liquid phase. This separation of the oil fraction 19 can alternatively or additionally be used to separate the oil fraction 28 carried out in the tenth step 27.

[0131] After the pH adjustment, separation 16 is preferably started within 60 minutes, preferably within 30 minutes. Protein precipitation to form an oil phase and separation, for example by centrifugation, can also be carried out simultaneously, for example by introducing an acid or a coagulating salt into a centrifuge or separator or decanter.

[0132] The separated protein phase 17 preferably has a lecithin content of less than 0.5% by weight.

[0133] In a fifteenth step, the protein phase 17 can then be dried 20. Spray drying or, in particular, gentle grinding drying of the product can be used here.

[0134] The oil-free protein phase thus obtained can be used as protein meal 32, in particular in the food and feed industry.

[0135] In the context of the present invention, oil-free describes a protein phase which has less than 3% by weight, in particular less than 1% by weight, of oil in the dried protein phase.

[0136] Reference mark

[0137] 1. Soybeans

[0138] 2. Storage tank

[0139] 3. Cleaning system

[0140] 4. Soften

[0141] 5. Water

[0142] 6. Crushing

[0143] 7. Increased pH

[0144] 8.NaOH or NaHCO3 solution

[0145] 9. Alkaline slurry

[0146] 10. Separation

[0147] 11. Okara

[0148] 12. Soy milk

[0149] 13. pH decreases

[0150] 14.Acid

[0151] 15. Organic solvents

[0152] 16. Separation

[0153] 17. Protein phase

[0154] 18. Liquid Phase

[0155] 19. Oil phase

[0156] 20. Drying

[0157] 21. Concentration of soy milk

[0158] 22. Displacement Extraction

[0159] 23. Series Operation

[0160] 24. Knead

[0161] 25. Strong stirring

[0162] 26. Knead

[0163] 27. Separation

[0164] 28. Oil phase

[0165] 29. Dealcoholization

[0166] 30. Sedimentation

[0167] 31. Oil-free suspension

[0168] 32. Protein powder

Claims

1. A method for obtaining protein (17) from soy milk (12), comprising: i. Provide soy milk (12); ii. adding aqueous alcohol (15) having a concentration of less than 80% by volume to the soy milk, thereby forming an organic aqueous suspension, wherein the addition of aqueous alcohol causes a shift in the solubility equilibrium and performs displacement extraction (22), wherein the volume of aqueous alcohol is selected in such a way that the organic solvent content of the organic aqueous suspension after step ii is at least 15% by volume and the dry matter content of the suspension is at least 5%; iii. separating the oil phase from the suspension (28); iv. coagulating the protein to form at least one protein phase (17) by adjusting the suspension (13) to a pH value less than pH = 7 or by adding a protein coagulant-forming salt; and v. separating (16) a protein phase (17) having a residual oil content of less than 5% by weight, based on the dry matter content of the protein phase (17), from the suspension.

2. The method according to claim 1, characterized in that In step i, soy milk (12) is provided by obtaining soy milk (12) from a natural substance mixture of soybeans (1), wherein the natural substance mixture is first pulverized (6) and processed by pH adjustment (7) and addition (4) of a polar solvent (5) to form a flowable alkaline slurry (9), which, in addition to lipids, also contains proteins (17), lecithin and solids, wherein the processing of the slurry (9) is carried out while forming two separate fractions in the form of okara (11) and soy milk (12).

3. The method according to claim 2, characterized in that The pH was adjusted to an alkaline pH value greater than pH=7.

2.

4. The method according to claim 2, characterized in that: The polar solvent (5) is water.

5. The method according to claim 1, characterized in that Aqueous alcohols are aliphatic alcohols.

6. The method according to claim 5, characterized in that Aqueous alcohols are aliphatic alcohols having a chain length of less than 6 carbon atoms.

7. The method according to claim 5, characterized in that The aqueous alcohol is isopropyl alcohol.

8. The method according to claim 1, characterized in that: Aqueous alcohol is added having an alcohol content of 50-80% by volume.

9. The method according to claim 1, characterized in that: The pH in step iv (13) is adjusted to a pH value greater than pH=3.

5.

10. The method according to claim 9, characterized in that The pH in step iv is adjusted to a pH value between pH=3.8 and 6.

0.

11. The method according to claim 9, characterized in that The pH is adjusted in step iv to a pH value between pH = 4.2 and 4.

7.

12. The method according to claim 1, characterized in that The soy milk provided is adjusted to a dry matter content of more than 12% by concentration (21) while reducing the water content of the soy milk.

13. The method according to claim 12, characterized in that The provided soy milk is adjusted to a dry matter content greater than 15%.

14. The method according to claim 1, characterized in that After step ii, the content of aqueous alcohol (15) in the suspension is greater than 20% by volume.

15. The method according to claim 14, characterized in that After step ii, the content of aqueous alcohol (15) in the suspension is between 25-45% by volume.

16. The method according to claim 1, characterized in that The soy milk provided in step i. has a pH value greater than pH=8.

17. The method according to claim 16, characterized in that The soy milk provided in step i has a pH value between pH=8.2 and 9.

8.

18. The method according to claim 1, characterized in that After the addition of aqueous alcohol (15) in step ii, a series of operations (23) of at least one kneading (24, 26) are performed.

19. The method according to claim 18, characterized in that After the addition of the aqueous alcohol in step ii, a series of operations (23) of at least one kneading (24, 26) is carried out at a stirring rate of less than 100 rpm.

20. The method according to claim 18, characterized in that At least one vigorous stirring is performed (25).

21. The method according to claim 20, wherein the stirring rate of the at least one intensive stirring (25) exceeds 500 rpm.

22. The method according to claim 18, characterized in that The kneading (24, 26) is performed at a stirring speed of less than 50 rpm.

23. The method according to claim 22, characterized in that The kneading (24, 26) is carried out at a stirring speed between 10-30 rpm.

24. The method according to claim 18, characterized in that The kneading (24, 26) is carried out at 40-70°C.

25. The method according to claim 18, characterized in that The kneading (24, 26) is performed at intervals between 5 and 30 minutes.

26. The method according to claim 20, characterized in that The intense stirring (25) is performed at a stirring rate of at least 1000 rpm.

27. The method according to claim 26, characterized in that The intense stirring (25) is performed at a stirring rate of 1000-12000 rpm.

28. The method according to any one of claims 18 to 27, characterized in that The series of operations (23) includes at least one kneading (24) and one intense stirring (25).

29. The method according to any one of claims 18 to 27, characterized in that Prior to step iv and after a series of at least one kneading (24, 26) and at least one intensive stirring (25), separation of the oil phase (28) from the suspension is carried out.

30. The method according to claim 1, characterized in that The separation (27) of the oil phase (28) prior to step iv is carried out by centrifugal separation (27).

31. The method according to claim 30, characterized in that The separation of the oil phase is carried out by means of a decanter or a separator.

32. The method according to claim 30, characterized in that The centrifugal separation (27) is carried out at a temperature above 20°C.

33. The method according to claim 32, characterized in that The centrifugal separation (27) is carried out at a temperature between 35-80°C.

34. The method according to claim 32, characterized in that The centrifugal separation (27) is carried out at a temperature between 35-45°C.

35. The method according to claim 1, characterized in that Step iv is preceded by dealcoholation (29).

36. The method according to claim 35, characterized in that Prior to step iv and after centrifugal separation (27) of the oil phase (28), dealcoholation (29) is carried out.

37. The method according to claim 35, characterized in that The dealcoholation (29) is carried out by evaporation of the alcohol.

38. The method according to claim 1, characterized in that After step iv, the suspension is transferred to a container to precipitate (30) the protein.

39. The method according to claim 38, characterized in that The precipitation (30) is carried out at a temperature above 20°C.

40. The method according to claim 39, characterized in that The precipitation (30) is carried out at a temperature between 50-80°C.

41. The method according to claim 39, characterized in that The precipitation (30) is carried out at a temperature between 60-75°C.

42. The method according to claim 38, characterized in that The precipitation (30) is carried out over a period of time between 5 and 20 minutes.

43. The method according to claim 1, characterized in that The separation (16) in step v. is a centrifugal separation.

44. The method according to claim 43, characterized in that The centrifugal separation is performed by means of a decanter.

45. The method according to claim 43, characterized in that The centrifugal separation is carried out in a centrifuge or a decanter, and the separation range, the so-called cut-off value, is between 1.0 and 100 μm.

46. ​​The method according to claim 1, characterized in that The protein separation (16) is followed by drying (20).

47. The method according to claim 1, characterized in that The protein phase (17) separated in step v. has less than 0.5% by weight of lecithin.

48. The method according to claim 1, characterized in that Steps i. to iii. are carried out at a temperature ranging from 35°C to a maximum of 85°C.

49. The method according to claim 2, characterized in that The provision of the alkaline slurry (9) within the provision of soy milk (12) is carried out at a temperature in the range of 35°C to a maximum of 85°C.

50. The method according to claim 2, characterized in that Step i. The polar solvent (5) previously used to form the flowable alkaline slurry (9) in the provided soy milk (12) is water, wherein the volume of the water is selected to adjust to a dilution factor greater than 2.

0.

51. The method according to claim 50, characterized in that The volume of water was chosen to adjust to a dilution factor of at least 3.

0.

52. The method according to claim 1, characterized in that The separation (16) in step v begins within 60 minutes after performing step iv.

53. The method according to claim 52, characterized in that The separation (16) in step v begins within 30 minutes after performing step iv.

54. The method according to claim 1, characterized in that The protein phase (17) was obtained without adding hexane or ether.

55. The method according to claim 1, characterized in that The pH adjustment (13) in step iv is carried out by adding an organic or inorganic acid (14).

56. The method according to claim 1, comprising the following steps: i. Provide soy milk (12); ii. Concentrating (21) soy milk (12) to increase the dry matter content; iii. adding an aqueous short-chain alcohol having 1 to 5 carbon atoms to form an aqueous alcohol suspension, wherein the alcohol content of the aqueous alcohol suspension after step iii is at least 15% by volume, iii.i A series of operations (23) consisting of at least one kneading (24, 26) with a stirring rate of less than 100 rpm and / or at least one intensive stirring (25) with a stirring rate of at least 500 rpm; iii.ii separation of the oil from the suspension (27) to form a suspension having an oil content of less than 5% by weight in the dry material; iii.iii optionally reducing the alcohol content (29); iv. adjusting the suspension (13) to a pH value less than pH = 7 to form at least one protein phase and at least one liquid phase (18); iv.i optionally precipitating (30) the protein as a solid phase; v. separation (16) of a protein phase (17) from the suspension, the protein phase having a residual oil content of less than 5% by weight, based on the dry matter of the protein phase (17), and vi. Drying (20) the protein phase (17) into protein powder.

57. The method according to claim 56, characterized in that In step i., soy milk (12) with a pH greater than 7.2 is provided.

58. The method according to claim 56, characterized in that In step iii. ethanol and / or isopropanol is added.

59. The method according to claim 56, characterized in that The alcohol content of the aqueous alcoholic suspension after step iii. is at least 20% by volume.

60. The method of claim 56, wherein: The separation of the oil from the suspension in step iii.ii (27) is a first centrifugal separation.

61. The method according to claim 56, characterized in that The separation of the oil from the suspension in step iii.ii (27) results in a suspension having an oil content of less than 3% by weight in the dry matter.

62. The method according to claim 56, characterized in that In step iii.iii, the alcohol content is reduced by distillation (29).

63. The method according to claim 56, characterized in that In step iii.iii, the alcohol content is reduced with recovery of the alcohol (29).

64. The method according to claim 56, characterized in that In step iv., the suspension is adjusted (13) to a pH value between pH=3.5 and pH=6.

65. The method of claim 56, wherein: The separation (16) of the protein phase (17) from the suspension in step v. is a second centrifugal separation.

66. The method of claim 56, wherein: In step v. the protein phase (17) has a residual oil content of between 1 and 3% by weight.

67. A method for obtaining protein (17) from a natural substance mixture of soybean (1) material, wherein the natural substance mixture is firstly comminuted (6) and processed by pH adjustment (7) and addition of a polar solvent (4) to form a flowable alkaline slurry (9) which contains, in addition to polar lipids, protein (17), lecithin and solids, characterized in that Follow these steps: A processes the slurry (9) to form two separate fractions in the form of okara (11) and soy milk (12), and B. Processing soy milk into a protein phase according to the method of any one of claims 1 to 66.

68. The method according to claim 67, characterized in that The comminution of the natural substance mixture is carried out by wet grinding.

69. A soy protein meal prepared by the process of any one of claims 1 to 68 having an oil content of up to 5% oil in the dry matter and a protein content of at least 70% protein in the dry matter, wherein the soy protein meal is absolutely hexane-free and ether-free.

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