Method for reducing purine in soybeans for preparing bean products

Abstract

The invention discloses a method for reducing purine in soybeans for preparing bean products, and relates to the technical field of food processing. The method comprises the following steps: obtaining food raw materials, and crushing the food raw materials into flakes or granules; the sheet-shaped or granular food raw materials are soaked, ultrasonic treatment is carried out through ultrasonic waves with three different frequencies during soaking, the ultrasonic waves with the three different frequencies are 10 kHz to 35 kHz, 35 kHz to 60 kHz and 60 kHz to 100 kHz respectively, water is changed in the ultrasonic treatment process, and the food raw materials subjected to ultrasonic treatment are obtained; and preparing the food raw materials subjected to ultrasonic treatment into the low-purine bean product. The method for reducing the purine in the soybean for preparing the bean product has the beneficial effects that the purine in the soybean raw material can be effectively removed, so that the purine content in the soybean product food is reduced, and flavor substances are reserved to the greatest extent.

Description

Technical Field

[0001] The present invention relates to the technical field of food processing, and in particular to a method for reducing purine in soybeans for preparing soy products. Background Art

[0002] Purine is an organic compound with the molecular formula C5H4N4 and is a key component of nucleic acids. Common purines include adenine, guanine, xanthine, and hypoxanthine. The final metabolite of purine in the body is uric acid, a direct cause of hyperuricemia and gout. Excessive intake of foods high in purines can lead to elevated uric acid levels in the blood, leading to hyperuricemia. 5%-12% of patients with hyperuricemia develop gout if untreated.

[0003] To prevent hyperuricemia, relevant departments recommend that healthy people generally limit their daily purine intake to no more than 250mg. To allow gout patients, hyperuricemia patients, and healthy individuals to enjoy a wide variety of delicious foods, removing purines from food, thereby reducing the purine content in food, is of great significance to consumers, especially those with special needs, in enjoying foods originally high in purine. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art by providing a method for preparing a low-purine soy product food ingredient. Specifically, the present invention provides a novel method for preparing a low-purine soy product food ingredient, thereby significantly reducing the purine content of soy products and thereby satisfying the consumption needs of consumers and special populations of high-purine foods.

[0005] The technical solutions of the present invention are as follows: A first aspect of the present invention provides a method for reducing purine in soybeans for preparing soy products, comprising the following steps: Obtaining food materials, and crushing the food materials into flakes or granules; soaking the flaky or granular food material, and simultaneously ultrasonically treating the food material with three different frequencies of ultrasound, wherein the three different frequencies of ultrasound are 10 kHz to 35 kHz, 35 kHz to 60 kHz, and 60 kHz to 100 kHz, respectively, and changing the water during the ultrasonic treatment process to obtain the ultrasonically treated food material; The ultrasonically treated food raw materials are prepared into low-purine soy products.

[0006] Compared to existing technologies, this invention utilizes ultrasonic treatment of crushed soybeans at three different powers and frequencies to dissolve purines, effectively reducing the purine content in soybeans and providing low-purine soy products for gout patients. Ultrasonic treatment during the soaking stage before steaming or boiling is simpler than other methods that treat the soybeans after boiling, mid-cooking, or cooking. The resulting food has less nutrient loss, a better flavor, and is suitable for a wider range of patients.

[0007] Preferably, the food material is soybean, and the soybean is pre-processed into half beans or granules.

[0008] Preferably, the method of soaking the flaky or granular food material comprises: soaking at 20°C to 45°C for 2h to 5h, Preferably, the ultrasonic treatment time is 90 min to 240 min, the ultrasonic treatment temperature is 20° C. to 45° C., and the ultrasonic treatment power is 200W to 400W.

[0009] Preferably, the ultrasonic treatment time is 120 min to 210 min, the ultrasonic treatment temperature is 25° C. to 40° C., and the ultrasonic treatment power is 250 W to 350 W.

[0010] Preferably, the three frequencies of ultrasound are 15 kHz to 30 kHz, 40 kHz to 55 kHz, and 65 kHz to 95 kHz, respectively.

[0011] Preferably, the three frequencies of ultrasound are 20 kHz to 25 kHz, 40 kHz to 50 kHz, and 70 kHz to 90 kHz, respectively.

[0012] Preferably, the water is changed 2 to 5 times during the ultrasonic treatment. Preferably, the purine removal rate in the food raw material after soaking, ultrasonic treatment, and filtration is 40% to 70%. The purine substances after soaking and ultrasonic filtration achieve the best removal effect, with a removal rate of 40% to 70%, obtaining a low-purine raw material for preparing soy products. This soybean raw material can be used to prepare low-purine soy products such as low-purine soy milk, dried tofu, water tofu, bean curd skin, fermented soybean paste, vegetarian chicken, and bean curd sticks.

[0013] Preferably, the soy product is at least one of low-purine soy milk, dried tofu, water tofu, bean curd skin, fermented bean curd, vegetarian chicken, and bean curd sticks; The steps of preparing the low-purine soy milk include: Soybeans are weighed and pre-processed into half-bean or granular raw materials. The half-bean or granular raw materials are washed, immersed in water, heated to 25°C~45°C in a constant temperature water bath, and soaked for 2h~5h. While soaking, the flaked or granular soybeans are treated with ultrasound at frequencies of 10kHz~35kHz, 35kHz~60kHz, and 60kHz~100kHz, for a time of 90min~240min, at a temperature of 20°C~45°C, and at a power of 200W~400W. The water is changed 2~5 times during the treatment process. The soaked half-bean or granular raw materials are drained, ground with water, and separated into pulp and residue to obtain purine-reduced soy milk, which is then used to produce low-purine soy products.

[0014] The second aspect of the present invention provides a low-purine soy product prepared by the method described.

[0015] The present invention has at least one of the following beneficial effects: 1. Compared with the existing technology, the present invention crushes soybeans into flakes or granules to make purine easier to precipitate during soaking; but it cannot be crushed into powder because powdered soybeans will affect the filtering efficiency.

[0016] 2. Compared with the existing technology, the present invention uses three different powers and frequencies of ultrasonic treatment during soaking, which can make purine substances more easily dissolved. Compared with the ultrasonic treatment of a single frequency, the effect is better.

[0017] 3. Compared with the existing technology, the ultrasonic treatment of the present invention is before the soybeans are cooked, which makes it easy to separate the purine substances that are precipitated. If ultrasonic treatment is used after cooking, a large amount of other substances such as proteins, sugars, etc. will be precipitated at the same time as the purine substances. It is not easy to separate the precipitated purine substances. If they are discarded together, the flavor and nutrition will be affected. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The present invention provides a flow chart of a method for reducing purine in soybeans used to prepare soy products. DETAILED DESCRIPTION

[0019] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0021] See also Figure 1 , shown is a flow chart of a method for reducing purine in soybeans for preparing soy products according to one embodiment of the present invention, the method comprising steps S01 to S03, wherein: Step S01: obtaining food raw materials and crushing soybeans into flakes or granules. The purpose of crushing soybeans is to facilitate the precipitation of purine substances; Step S02: soaking and ultrasonically treating the flake or granular soybeans, and filtering to prepare edible soy milk as a low-purine food raw material; Step S03: various soy products are prepared using low-purine soy milk as a main raw material.

[0022] It should be noted that the low-purine food raw material is edible soy milk, and the steps for preparing the edible soy milk are as follows: Weigh a quantity of soybeans and crush them into half-beans or granules. Wash the half-beans or granules, submerge them in water, and soak them in a constant-temperature water bath heated to 20°C-45°C for 2-5 hours. While soaking, ultrasonically treat the soybean flakes or granules at frequencies of 10kHz-35kHz, 35kHz-60kHz, or 60kHz-100kHz, for 90-240 minutes, at a temperature of 20°C-45°C, and at a power of 200W-400W. The water is changed 2-5 times during the soaking process. Drain the ultrasonically treated half-beans or granules, mix them in a soybean-to-water ratio of 1:6 to 1:10, boil them, and grind them. The resulting slurry is the soymilk raw material. After homogenization, packaging, and sterilization, purine-reduced edible soymilk is obtained. The resulting soymilk can be used to produce low-purine soy products.

[0023] In summary, according to the above-mentioned method for reducing purine in soybeans for preparing soy products, by subjecting crushed soybeans to three methods of ultrasonic treatment with different powers and frequencies, purine substances are dissolved, which can effectively reduce the purine content in soybeans, provide low-purine soy products for gout patients, and can effectively reduce the purine content in soy products, providing low-purine soy products for gout patients. Compared with traditional methods, the low-purine soy products prepared by the present invention have less nutrient loss and are suitable for a wider range of people.

[0024] The present invention is further described in detail below using specific examples, but the present invention is not limited to the following specific examples. 1000g of high-quality, plump soybeans were selected and crushed into flakes or granules. After washing, the soybeans were soaked in an ultrasonic bath at 35°C for 3 hours in distilled water (4 times their weight). The soybean flakes or granules were then subjected to ultrasonic treatment at three different frequencies: 20 kHz, 40 kHz, and 80 kHz, for 180 minutes at a power of 300 W. The water was changed three times during the treatment process. The soybeans were drained and mixed with water at a mass ratio of 1:8. The soybeans were boiled for 45 minutes, ground five times, and boiled at 100°C for 8 minutes to obtain the resulting slurry, which was then used as the soymilk raw material. After homogenization, packaging, and sterilization, the edible soymilk was obtained.

[0025] The purine content in edible soy milk was determined using the method in QBT5888-2023.

[0026] After determination, its purine content is 15.01 mg / 100 g.

[0027] Comparative Example 1 This comparative example 1 is basically the same as the example 1, except that the soybean raw material is not crushed and not ultrasonically treated. That is, the soybeans are directly soaked and then drained, and then soy milk is made according to the same method. The method for determining purine content is the same as that in Example 1.

[0028] After measurement, its purine content is 30.28 mg / 100 g.

[0029] Comparing Example 1 with Comparative Example 1, it can be seen that the purine content in the edible soy milk prepared in Example 1 is significantly lower than that in Comparative Example 1, indicating that crushing the soybeans and ultrasonically treating the soybeans while soaking them can help reduce the purine content in the edible soy milk.

[0030] Example 2 Using soy milk, a low-purine food, as raw material, the dried tofu is made through squeezing, shaping, cooling, and cutting. The details are as follows: 1000g of high-quality, plump soybeans were selected and crushed into flakes. After washing, the soybeans were soaked in an ultrasonic bath at 35°C for 3 hours in distilled water (4 times their weight). The soybean flakes or granules were then ultrasonically treated at frequencies of 20 kHz, 40 kHz, and 80 kHz for 180 minutes at a power of 300 W. The water was changed three times during the treatment process. The soybeans were drained and mixed with water at a ratio of 1:8. The soybeans were boiled for 45 minutes, ground five times, and boiled at 100°C for 8 minutes to obtain the soymilk. The slurry was adjusted to a concentration of 6% and a pH of 7.5. The slurry was then stirred and allowed to rest for 30 minutes to obtain the dried tofu. The dried tofu was then pressed, shaped, cooled, and cut into pieces. The dried tofu was then packaged and sterilized to obtain edible dried tofu.

[0031] The method for determining purine content is the same as that in Example 1.

[0032] After determination, its purine content is 35.08 mg / 100 g.

[0033] Comparative Example 2 Comparative Example 2 is essentially the same as Example 2, except that the soybeans are not crushed or ultrasonically treated. Instead, the soybeans are soaked and drained, and then prepared into soymilk using the same method. The soybeans are then pulped, allowed to stand, pressed, shaped, cooled, and cut into pieces to produce edible dried tofu. The dried tofu are then packaged and sterilized.

[0034] The method for determining purine content is the same as that in Example 1.

[0035] After measurement, its purine content is 60.71 mg / 100 g.

[0036] Comparing Example 2 with Comparative Example 2, it can be seen that the purine content in the edible soy milk prepared in Example 2 is significantly lower than that in Comparative Example 2, indicating that crushing the soybeans and ultrasonically treating the soybeans while soaking them can help reduce the purine content in edible dried tofu.

[0037] The purine content in the edible dried tofu prepared in Example 2 is higher than the purine content in the edible soy milk prepared in Comparative Example 1 because the edible dried tofu is squeezed to remove part of the water, and its purine content is higher than that in the edible soy milk.

[0038] Comparative Example 3 (Application No. 201610400749.4) Comparative Example 3 and Example 1 have different production processes, but both use ultrasonic treatment of soybeans. The differences between Example 1 and Comparative Example 3 are: 1. Example 1 is treated with ultrasonic frequencies of 20 kHz, 40 kHz, and 80 kHz while soaking; Comparative Example 3 is treated with 350W. 2. Example 1 crushes the soybeans into flakes or granules; Comparative Example 3 does not crush them. 3. Example 1's ultrasonic treatment is before cooking; Comparative Example 3's is after cooking. 4. The final products are different. Example 1 is soy milk; Comparative Example 3 is soybeans. Cooked soybeans are difficult to make into soy milk, and even more difficult to use them as raw materials for making related soy products.

[0039] The specific method of comparative example 3 is as follows: a soybean depurine process, comprising the following processing steps: 1. removing impurities, washing and removing impurities from the soybeans; 2. soaking, soaking the soybeans in warm water; the temperature of the warm water is controlled at 40°C, and the soaking is carried out for 10 hours; the mass ratio of soybeans to warm water is 1:2; 3. boiling beans, placing the soaked soybeans in a pot and boiling them, controlling the water temperature to 70°C, boiling for 30 minutes, and then raising the water temperature to 100°C; 4. cold soaking, taking the soybeans out of the 100°C water and quickly putting them into cold water, which can not only quickly remove the bean skins, but also promote changes in the soybean tissue structure; 5. ultrasonic treatment: placing 1 part of soybeans in 5 parts of pure water, controlling the water temperature at 40°C, and using an ultrasonic generator for ultrasonic treatment, thereby accelerating the rupture of the soybean cell wall and promoting the precipitation of purine substances in the cells; the power of the ultrasonic generator is controlled at 350W, and the ultrasonic treatment is carried out for 30 minutes; 6. acidification heat treatment, placing the soybeans in an acidic solution, and controlling the mass ratio of soybeans to the acidic solution at 1:2, Then, heat to 60°C and soak for 60 minutes. The acidic solution is hydrochloric acid. 7. Soak the soybeans in running water for 60 minutes to remove the strong acid and residual purines. The purine content in the soybeans drops from 150mg to about 30mg, a reduction rate of nearly 80%.

[0040] Comparative Example 4 Comparative Example 2 is basically the same as Example 1, except that only two ultrasonic treatments of different frequencies, 20 kHz and 40 kHz, were performed during the soaking process. Other aspects are the same as Example 1.

[0041] After determination, its purine content is 19.45mg / 100g.

[0042] Comparative Example 5 Comparative Example 2 is basically the same as Example 1, except that only two ultrasonic treatments of different frequencies, 20 kHz and 80 kHz, were performed during the soaking process. Other aspects are the same as Example 1.

[0043] After determination, its purine content is 20.03mg / 100g.

[0044] Comparative Example 6 Comparative Example 2 is basically the same as Example 1, except that only two ultrasonic treatments of different frequencies, 40 kHz and 80 kHz, were performed during the soaking process. Other aspects are the same as Example 1.

[0045] After determination, its purine content is 19.41 mg / 100 g.

[0046] Comparative Example 7 Comparative Example 2 is basically the same as Example 1, except that only four different frequencies of ultrasonic treatment were performed during the soaking process: 20 kHz, 40 kHz, 80 kHz, and 100 kHz. Other procedures are the same as Example 1.

[0047] After determination, its purine content is 14.93 mg / 100 g.

[0048] Comparative Example 8 Comparative Example 2 is basically the same as Example 1, except that only one ultrasonic treatment of different frequency, 80 kHz, is performed during the soaking process. Other aspects are the same as Example 1.

[0049] After determination, its purine content is 23.05mg / 100g.

[0050] Comparing Example 1 with Comparative Examples 4 to 8, it can be seen that the purine content in the soymilk prepared using only one or two different frequencies was higher than that obtained using three different frequencies of ultrasonic treatment in Example 1. The purine content in the soymilk prepared using four different frequencies of ultrasonic treatment was similar to that obtained using three different frequencies of ultrasonic treatment in Example 1, with a less pronounced effect but increased cost. This indicates that using three different frequencies of ultrasonic treatment is helpful in reducing purine content and is cost-effective.

[0051] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A method for reducing purine in soybeans for preparing soy products, characterized in that: The following steps are involved: Obtaining food materials, and crushing the food materials into flakes or granules; soaking the flaky or granular food material, and simultaneously ultrasonically treating the food material with three different frequencies of ultrasound, wherein the three different frequencies of ultrasound are 10 kHz to 35 kHz, 35 kHz to 60 kHz, and 60 kHz to 100 kHz, respectively, and changing the water during the ultrasonic treatment process to obtain the ultrasonically treated food material; The ultrasonically treated food raw materials are prepared into low-purine soy products.

2. The method according to claim 1, characterized in that The food material is soybean, which is pre-processed into half beans or granules.

3. The method according to claim 1, characterized in that The method of soaking the flaky or granular food material comprises: soaking at 20° C. to 45° C. for 2 h to 5 h.

4. The method according to claim 1, wherein The ultrasonic treatment time is 90 min to 240 min, the ultrasonic treatment temperature is 20° C. to 45° C., and the ultrasonic treatment power is 200W to 400W.

5. The method according to claim 1, wherein The ultrasonic treatment time is 120 min~210 min, the ultrasonic treatment temperature is 25℃~40℃, and the ultrasonic treatment power is 250W~350W.

6. The method according to claim 1, characterized in that The three frequencies of ultrasound are 15 kHz~30 kHz, 40kHz~55 kHz, and 65kHz~95 kHz.

7. The method according to claim 1, characterized in that The three frequencies of ultrasound are 20 kHz~25 kHz, 40kHz~50 kHz, and 70kHz~90kHz.

8. The method according to claim 1, characterized in that The water was changed 2–5 times during the ultrasonic treatment.

9. The method according to claim 1, characterized in that The removal rate of purines in food raw materials after soaking, ultrasonic treatment and filtration is 40%~70%; The soy product is at least one of low-purine soy milk, dried tofu, water tofu, bean curd skin, fermented bean curd, vegetarian chicken, and bean curd sticks; The steps of preparing the low-purine soy milk include: Soybeans are weighed and pre-processed into half-bean or granular raw materials. The half-bean or granular raw materials are washed, immersed in water, heated to 25°C~45°C in a constant temperature water bath, and soaked for 2h~5h. While soaking, the flaked or granular soybeans are treated with ultrasound at frequencies of 10kHz~35kHz, 35kHz~60kHz, and 60kHz~100kHz, for a time of 90min~240min, at a temperature of 20°C~45°C, and at a power of 200W~400W. The water is changed 2~5 times during the treatment process. The soaked half-bean or granular raw materials are drained, ground with water, and separated into pulp and residue to obtain purine-reduced soy milk, which is then used to produce low-purine soy products.

10. A low-purine soy product, characterized in that: The method according to any one of claims 1 to 9 is used for preparation.

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