An industrialized soybean milk preparation method instead of traditional soybean milk preparation process

Abstract

The application discloses an industrialized soybean milk preparation method which replaces a traditional soybean milk preparation method. The industrialized soybean milk preparation method comprises the following steps: S1, grinding the completely soaked soybeans by using first washing residue water at a temperature of not higher than 60 DEG C, and separating the pulp and residue by using a separator after the grinding, so as to obtain raw soybean milk and first soybean residue; S2, extracting the first soybean residue by using hot water or hot second washing residue water with a temperature of 70-100 DEG C, and separating the pulp and residue by using a separator after the extraction, so as to obtain an extraction liquid and second soybean residue; wherein, the first washing residue water is obtained by adjusting the extraction liquid with water; S3, heating the raw soybean milk at a central temperature of 70-85 DEG C, and then heating the raw soybean milk to cook the pulp, so as to obtain soybean milk. The application not only solves the problem that the traditional soybean milk preparation method is difficult to be used for industrial pulp and residue separation, and realizes the industrialization of the hot water soybean milk preparation method, but also has the same effect as the traditional soybean milk preparation method.

Description

Technical Field

[0001] This invention belongs to the field of soybean food processing, and specifically relates to an industrial method for preparing soybean milk that replaces the traditional soybean washing process. Background Technology

[0002] Tofu is an important and traditional plant-based protein product in my country. Its production process mainly includes soy milk preparation, boiling, and coagulation (or pressing and draining). Soy milk preparation can be seen as the process of extracting protein, fat, and other substances from soybean raw materials, aiming to obtain soy milk that meets the requirements of high-quality soy product processing and achieves a higher raw material conversion rate. Currently, based on the production situation of soy products in my country, the main soy milk preparation methods include the raw soy milk method, the cooked soy milk method, and the hot water washing method. Different soy milk preparation processes not only differ in the yield, taste, and texture of tofu products, but also in the ease with which the corresponding production and processing equipment can be scaled up and industrialized.

[0003] The hot water extraction method is an ancient traditional soy milk making method in my country, mainly distributed in the southwest region, such as Shiping tofu and Jianshui tofu in Yunnan Province. Tofu produced using this method has a lower water content and stronger resilience. The hot water extraction method differs from the raw soy milk method and the cooked soy milk method in its extraction process. In the hot water extraction method, hot water is added to the ground soy milk and mixed thoroughly. The mixture is then filtered through a cloth to remove residue, and then the soy milk is cooked further. Our research found that compared to the raw soy milk method, the hot extraction process allows more protein and polysaccharides from the soy residue to enter the soy milk, improving the conversion rate of raw material components. Furthermore, the thermal shock and denaturation of soy milk protein during extraction differs from that in the cooked soy milk method, resulting in tofu with higher hardness, elasticity, and resilience. However, in the hot water extraction method, the protein and soybean fiber in the soy milk become highly bound after the addition of hot water, making it difficult for industrial separators to separate the pulp from the residue. Using extrusion separators is energy-intensive and costly. Therefore, due to the aforementioned problems, the traditional hot water washing method has not been industrialized. Currently, many regions still use the traditional manual washing method, which has low production efficiency and high hygiene and safety risks. Summary of the Invention

[0004] Therefore, the purpose of this invention is to provide an industrialized soybean milk preparation method that replaces the traditional soybean washing process. This method is a "hot water washing-stage heating pulping method" that has the same effect as the traditional soybean washing method. It solves the problem that the traditional soybean washing method is difficult to separate industrial pulp and residue, and realizes the industrialization of the hot water washing method.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] This invention provides a method for preparing industrial-scale soy milk, comprising the following steps:

[0007] S1. Grind the fully soaked soybeans with water or the first washing residue water at a temperature not exceeding 60°C. After grinding, use a separator to separate the pulp and residue to obtain raw soybean milk and the first soybean residue.

[0008] S2. The first soybean residue is extracted with hot water at 70-100℃ or hot second washing residue water. After extraction, the pulp and residue are separated by a separator to obtain the extract and the second soybean residue.

[0009] The first washing residue water is the washing residue water obtained by adjusting the extract with water;

[0010] S3. The raw soy milk is initially heated at a core temperature of 70-85°C, and then the temperature is increased to cook the soy milk to obtain soy milk.

[0011] In the above-mentioned industrialized method for preparing soy milk, the mass of the fully soaked soybeans can be 2.1 to 2.2 times that of the dried soybeans, such as 2.2 times; for example, the mass ratio of dried soybeans to water in the soaking step can be 1:(2 to 5); specifically, it can be 1:3.

[0012] In the grinding step, the mass ratio of soybeans to the first washing residue water can be 1:(5-12), specifically 1:7.

[0013] Preferably, the grinding temperature is 40–60°C, such as 50°C. When the grinding temperature is above 70°C, the protein and soybean residue fiber become highly thickened, significantly reducing the separation efficiency of the pulp-residue separator.

[0014] In the above-mentioned industrialized soybean milk preparation method, the mass ratio of the first soybean residue to the hot water at 70-100℃ (e.g., 100℃) or the hot second washing water can be 1:(4-8), specifically 1:4;

[0015] The heat preservation time in the extraction step can be 3 to 10 minutes, such as 3 minutes.

[0016] In the above-mentioned industrialized soybean milk preparation method, since the first washing water is the washing water obtained by adjusting the extract with water, the temperature and amount of the washing water must meet the requirements of step S1.

[0017] As an example, the first washing residue water is the washing residue water obtained by mixing the extract with room temperature tap water at a mass ratio of water to extract of 3:4, and the temperature after mixing is 50℃.

[0018] In the above-mentioned industrialized soybean milk preparation method, the second washing water is the washing water obtained by washing the second soybean residue with water (it can be heated to meet the temperature requirements);

[0019] As an example, the second washing water is the washing water obtained by washing the second soybean residue with a mass ratio of 1:(3-10) of the second soybean residue and water, specifically 1:4.

[0020] In the above-mentioned industrialized soy milk preparation method, tap water can be used directly unless otherwise specified.

[0021] In the above-mentioned industrialized soy milk preparation method, the separator is a centrifugal separator, a horizontal screw separator, or an extrusion separator.

[0022] In the above-mentioned industrialized soy milk preparation method, the initial heating is carried out by heat exchanger heating or by direct steam heating;

[0023] The initial heating temperature can specifically be the center temperature, such as 75°C;

[0024] The initial heating holding time can be 3 to 10 minutes, specifically 5 minutes;

[0025] The initial heating rate is 10-30℃ / min; at this heating rate, the soy milk is heated to the initial heating temperature within 2-3 minutes, specifically within 2 minutes.

[0026] In the above-mentioned industrialized soy milk preparation method, the boiling process involves heating the soy milk at normal pressure until the center temperature reaches 95-100°C and maintaining this temperature for 5-10 minutes, or keeping it at 95°C for 5 minutes; or...

[0027] The boiling process involves heating the slurry to 108–115°C under a micro-pressure of 0.05–0.1 MPa and maintaining the temperature for 5–10 minutes.

[0028] The present invention further provides soy milk obtained by any of the preparation methods described above. The soy milk of the present invention has a higher solids content.

[0029] The present invention also provides a method for preparing tofu, comprising the following steps: after cooling the soy milk obtained by any of the above preparation methods, a coagulant is added to coagulate it to obtain tofu.

[0030] In the above-mentioned method for preparing tofu, the coagulant is any one or a combination of glucono-delta-lactone (GDL), lactic acid bacteria fermented soy whey (fermented soy milk), brine, and gypsum.

[0031] As an example, the solids content of the soy milk is 9%;

[0032] The amount of coagulant added is 0.3% of the mass of the soy milk.

[0033] In the above-mentioned method for preparing tofu, the coagulation can be carried out under heating conditions, such as heating at 75°C for 40 minutes.

[0034] The tofu obtained by the above preparation method is also within the scope of protection of this invention. The tofu of this invention has high hardness, elasticity, and toughness. In this invention, increasing the grinding temperature and the material-to-liquid ratio, and washing the soybean residue with hot water can improve the extraction efficiency of solids. The stepped heating of the soybean milk can retain the high hardness, elasticity, and toughness of the traditional washing method.

[0035] The present invention has the following beneficial effects:

[0036] The traditional soybean washing method involves adding hot water to the ground soybean paste, causing the protein and soybean fiber in the paste to be rapidly heated in a short time. The soybean protein denatures under this thermal shock, while the soybean fiber also partially disintegrates and dissolves. Based on the principles of traditional soybean washing technology, this invention proposes a new pulping technique. Compared to the traditional method, this method separates the thermal reactions of soybean milk and soybean residue. 1) It avoids the simultaneous heating of soybean protein and soybean residue fiber in the traditional method, solving the problem of the difficulty in separating the protein and soybean residue after they are highly thickened and intertwined, even using a centrifuge; 2) Simultaneously, by subjecting the separated soybean milk to a short-term (e.g., within 2 minutes) initial heating treatment to a core temperature of 70-85°C, the degree of denaturation of the soybean protein is controlled, achieving the same denaturation effect as the soybean protein in the traditional method; 3) Furthermore, hot water treatment of the soybean residue causes some of the polysaccharides to dissolve, which are then mixed with soy milk protein and heated, cooked, and completely denatured at high temperatures. This process achieves the same component processing as the soybean milk produced by the traditional method, including the thermal interaction between polysaccharides and protein. This technology achieves essentially the same effect as the traditional pulping method and can be industrialized.

[0037] The soybean milk produced by this process has a higher solids content than the traditional washing and raw soy milk methods, which improves the production efficiency of soybean soy milk. The resulting tofu products have comparable hardness, elasticity, water retention and toughness to those produced by the traditional washing method. Among them, the hardness and elasticity of the silken tofu are increased by 18% and 12% respectively compared to the raw soy milk method, and the hardness and elasticity of the calcium sulfate tofu are increased by 45% and 4% respectively compared to the raw soy milk method. Attached Figure Description

[0038] Figure 1 This is a process flow diagram of the industrial soybean milk preparation method of the present invention, which replaces the traditional soybean washing process. Detailed Implementation

[0039] The present invention will now be described in further detail with reference to specific embodiments. The given embodiments are merely illustrative of the invention and not intended to limit its scope. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.

[0040] Unless otherwise specified, the methods used in the following embodiments are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following embodiments are commercially available.

[0041] Example 1

[0042] according to Figure 1 The process flow diagram shown illustrates the preparation of soy milk, with the specific steps as follows:

[0043] S1. Soak the soybeans completely (2.2 times the weight of the dried soybeans) and grind them into a paste at a mass ratio of 1:7 (soybeans:first washing residue water). Grind the paste at a temperature of 50°C and separate the paste and residue using a paste-residue centrifuge to obtain raw soybean milk and first soybean residue.

[0044] S2. The first soybean residue obtained by separating the pulp and residue in step S1 is extracted with hot second washing water at 100℃. The mass ratio of the first soybean residue to the hot second washing water is 1:4. After keeping it warm for 3 minutes, the pulp and residue are separated by a pulp and residue centrifuge to obtain the extract and the second soybean residue.

[0045] In step S1, the first washing water is obtained by mixing the extract obtained in S2 with room temperature water at a mass ratio of water to extract of 3:4, and the temperature after mixing is 50°C.

[0046] In step S2, the second washing water for extraction is the second washing water obtained by washing the second soybean residue with hot water. The mass ratio of the second soybean residue to tap water during washing is 1:4. Heating can be selected according to the temperature of the hot water and the temperature of the second soybean residue.

[0047] S3. Place the raw soy milk obtained in step S1 into a boiling water bath for initial heating. When the center temperature reaches 75°C, stop heating (heating rate is 25°C / min) and keep it warm for 5 minutes. Then continue heating for the second stage of cooking. Heat the soy milk until the center temperature reaches 95°C and keep it warm for 5 minutes to complete the cooking process.

[0048] S4. Cool the soy milk to 2-6℃ after heat exchange with ice water, adjust the solid content of the soy milk to 9%, add 0.3% GDL by weight of the soy milk, and place it in a 75℃ water bath for 40 minutes to coagulate the soy milk and obtain silken tofu.

[0049] Example 2

[0050] The process of making soy milk is the same as in Example 1. The solid content of the soy milk is adjusted to 9%, 0.3% CaSO4 by weight of the soy milk is added, and the mixture is placed in a water bath at 75°C for 40 minutes to coagulate the soy milk and obtain calcium sulfate tofu.

[0051] Comparative Example 1

[0052] The traditional hot water washing process is used to prepare soy milk and tofu. The specific steps are as follows:

[0053] 1) Soak the soybeans completely (2.2 times the weight of the dried soybeans), mix them with room temperature tap water at a mass ratio of 1:3 (based on the mass of the dried soybeans), grind them into a paste, and obtain soybean paste.

[0054] 2) Add 100℃ hot water at 4 times the weight of soybeans to the soybean paste and stir thoroughly. Keep the soybean paste at 85℃ for 3 minutes, then filter it with a 120-mesh filter cloth to separate and remove the soybean residue and obtain raw soybean milk.

[0055] The 100°C hot water added to the soybean paste is obtained in the same way as in Example 1, which is the washing water obtained by washing the soybean residue.

[0056] 3) Heat the obtained raw soy milk in a boiling water bath until the core temperature reaches 95℃ and keep it warm for 5 minutes to complete the cooking process;

[0057] 4) After the soy milk is cooked, cool it in an ice water bath to 2-6℃, adjust the solid content of the soy milk to 9%, add 0.3% GDL by weight of the soy milk, and place it in a 75℃ water bath for 40 minutes to coagulate the soy milk and obtain silken tofu.

[0058] As can be seen from Example 1 and Comparative Example 1, in Comparative Example 1, hot water was added directly to the ground soybean paste, and the thickened fiber and protein in the soybean paste were difficult to separate after binding. The only option was to use the traditional filter cloth separation method, which resulted in low processing efficiency and was not suitable for current industrial continuous production.

[0059] Comparative Example 2

[0060] The soy milk making process was the same as in Comparative Example 1, except that the solid content of the soy milk was adjusted to 9%, 0.3% CaSO4 by weight of the soy milk was added, and the mixture was placed in a 75°C water bath for 40 minutes to coagulate the soy milk and obtain calcium sulfate tofu.

[0061] Comparative Example 3

[0062] The specific steps for preparing soy milk and tofu using traditional raw soy milk processing are as follows:

[0063] 1) Soak fully soaked soybeans (2.2 times the weight of dry soybeans) are mixed with room temperature washing water (same as in Example 1) at a mass ratio of 1:7 (based on the weight of dry soybeans) and then ground into a paste. The soybean residue is removed by a paste-residue separator to obtain raw soybean milk; wherein, the washing water is obtained by washing the soybean residue.

[0064] 2) Heat the obtained raw soy milk in a boiling water bath. When the center temperature reaches 95℃, keep it warm for 5 minutes to complete the cooking process.

[0065] 3) After the soy milk is cooked, cool it in an ice water bath to 2-6℃, adjust the solid content of the soy milk to 9%, add 0.3% GDL by weight of the soy milk, and place it in a 75℃ water bath for 40 minutes to coagulate the soy milk and obtain silken tofu.

[0066] Comparative Example 4

[0067] The soy milk making process was the same as in Comparative Example 3, except that the solid content of the soy milk was adjusted to 9%, 0.3% CaSO4 by weight of the soy milk was added, and the mixture was placed in a 75°C water bath for 40 minutes to coagulate the soy milk and obtain calcium sulfate tofu.

[0068] The solids content of the soy milk obtained in the following examples and comparative examples was determined, and the results are shown in Table 1.

[0069] Table 1 Comparison of Soy Milk Solids Content in Examples and Comparative Examples

[0070]

[0071] The total solids content of soy milk was determined in accordance with GB / T 30885—2014 Plant Protein Beverages: Soy Milk and Soy Milk Beverages.

[0072] The texture of the tofu obtained in the following examples and comparative examples, namely, tofu with glucono-delta-lactone and tofu with calcium sulfate, was determined after cooling at 4°C overnight. The results are shown in Tables 2 and 3, respectively.

[0073] Two compression experiments were conducted using a texture analyzer TA-XI2i. The texture was measured under the following conditions: probe model TA25 / 1000, pre-test speed 1 mm / s, test speed 1 mm / s, post-test speed 1 mm / s, trigger point load 5 g, and compression distance 40%.

[0074] Sensory evaluation of tofu's resilience was conducted by cutting the sample into cubes measuring 0.5cm x 1cm x 3cm. The same force was applied to the longest two ends of the tofu, and the tofu was slowly bent in the same direction. The ease with which it broke was used to characterize resilience; the easier it was to break, the lower the resilience and the lower the sensory score.

[0075] Table 2 Comparison of the texture of lactone-based tofu obtained from the examples and comparative examples.

[0076]

[0077] Table 3 Comparison of the texture of gypsum tofu obtained in the examples and comparative examples.

[0078]

[0079] As can be seen from Tables 1-3, the soybean milk produced by the method of the present invention has a higher solids content than the traditional washing method and the raw soy milk method, which improves the production efficiency of soybean soy milk production. Moreover, the hardness, elasticity, water retention and toughness of the obtained tofu products are comparable to those of the traditional washing method. Among them, the hardness and elasticity of the silken tofu are increased by 18% and 12% respectively compared with the raw soy milk method, and the hardness and elasticity of the calcium sulfate tofu are increased by 45% and 4% respectively compared with the raw soy milk method.

[0080] The present invention has been described in detail above. Those skilled in the art will recognize that the invention can be practiced in a wide range of ways with equivalent parameters, concentrations, and conditions without departing from its spirit and scope. While specific embodiments have been provided, it should be understood that further modifications can be made to the invention. In summary, according to the principles of the invention, this application is intended to include any changes, uses, or improvements to the invention, including modifications made using conventional techniques known in the art that depart from the scope disclosed herein.

Claims

1. A method for preparing industrial-scale soy milk, comprising the following steps: S1. Grind the fully soaked soybeans with water or the first washing residue water at 40~60℃. After grinding, use a separator to separate the pulp and residue to obtain raw soybean milk and the first soybean residue. S2. The first soybean residue is extracted with hot water at 70~100℃ or hot second washing residue water. After the extraction is completed, the pulp and residue are separated by a separator to obtain the extract and the second soybean residue. in, The first washing residue water is the washing residue water obtained by adjusting the extract with water; The second washing water is the washing water obtained by washing the second soybean residue with water; S3. The raw soy milk is initially heated at a core temperature of 70~85℃, and then the temperature is increased to cook the soy milk to obtain soy milk.

2. The method for preparing industrial-scale soy milk according to claim 1, characterized in that: The fully soaked soybeans should have a mass of 2.1 to 2.2 times that of the dried soybeans. In the grinding step, the mass ratio of soybeans to the first washing residue water is 1:(5~12).

3. The method for preparing industrial-scale soy milk according to any one of claims 1-2, characterized in that: The mass ratio of the first soybean residue to the hot water at 70~100℃ or the hot second washing water is 1:(4~8). The heat preservation time in the extraction step is 3 to 10 minutes.

4. The method for preparing industrial-scale soy milk according to claim 1 or 2, characterized in that: The initial stage heating is achieved by using a heat exchanger or direct steam heating. The initial heating holding time is 3-10 minutes; The initial heating rate is 10~30℃ / min.

5. The method for preparing industrial-scale soy milk according to claim 1 or 2, characterized in that: The boiling process involves heating the soy milk at normal pressure until the center temperature reaches 95-100℃, then maintaining this temperature for 5-10 minutes; or... The boiling process involves heating the slurry to 108–115°C under a micro-pressure of 0.05–0.1 MPa and holding the temperature for 5–10 minutes.

6. Soy milk obtained by the preparation method according to any one of claims 1-5.

7. A method for preparing tofu, comprising the following steps: adding a coagulant to the soy milk obtained by the preparation method according to any one of claims 1-5 to coagulate it, thereby obtaining tofu.

8. The method for preparing tofu according to claim 7, characterized in that: The coagulant is any one or a combination of glucono-δ-lactone, lactic acid bacteria fermented soy whey, brine, and gypsum.

9. Tofu obtained by the preparation method according to claim 7 or 8.

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