Process for preparing hard bean curd through staged pressing and pressing device of hard bean curd

Abstract

The invention relates to the technical field of bean product processing, in particular to a hard bean curd preparation process adopting staged pressing and a pressing device of the hard bean curd preparation process. Comprising five stages of pressure control, in the first three stages, a pressing device is adopted for low-speed progressive pressing, the pressure is smaller than or equal to 20 Kpa, in the last two stages, rapid high-pressure pressing is adopted, the pressure is larger than or equal to 30 kPa, and the pressing time of the five stages is 25 + / -2 min. The pressing device comprises a pressing box and a hydraulic assembly, the pressing box comprises a box body (1) and a pressing plate, the hydraulic assembly is vertically connected to the upper side of the pressing plate, the pressing plate comprises a connecting frame body and a movable bottom face, the movable bottom face comprises a plurality of adjacent strip-shaped plates, and spring supporting rods are connected between the connecting frame body and the strip-shaped plates. A progressive extrusion assembly is arranged in the connecting frame body and comprises a connecting shaft and a plurality of sets of extrusion pieces. In the pressing process, water is gradually discharged slowly and rapidly, the surface of the bean curd can be effectively prevented from crusting too early, and efficient discharge and uniform distribution of water are guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of soy product processing, specifically to a preparation process for old tofu with staged pressing and a pressing device therefor. Background Art

[0002] Traditional old tofu pressing processes mostly adopt single or simple multiple pressings, which have problems such as inaccurate control of water content, loose internal structure, and poor skin formation on the surface.

[0003] Traditional old tofu preparation processes usually adopt a single pressing mode or a simple two-stage pressing method. The simple pressing method results in a relatively single water drainage path in the tofu, and water retention areas are likely to form inside the tofu blank; while using high-pressure rapid pressing easily causes premature skin formation on the surface, hindering the continuous drainage of internal water, and correspondingly also leading to an extended pressing time.

[0004] Therefore, the present application provides a preparation process for old tofu with staged pressing and a pressing device therefor, to solve the problems of simple pressing mode and low pressing efficiency in the pressing process of old tofu in the prior art. Summary of the Invention

[0005] To solve the above problems, the present invention provides a preparation process for old tofu with staged pressing and a pressing device therefor.

[0006] The technical solution adopted by the present invention to solve its technical problems is: A preparation process for old tofu with staged pressing includes five-stage pressure control. Among them, in the first three stages, a pressing device is used for slow progressive pressing with a pressure ≤ 20 Kpa, and in the last two stages, rapid high-pressure pressing is adopted with a pressure ≥ 30 kPa. The pressing time for the five stages is 25 ± 2 min.

[0007] As an optimization, the third stage is a pulse pressing mode, and the pressing / release time ratio is 4:1.

[0008] As an optimization, the specific content of the five-stage pressure control is as follows: S1. First-stage pressing: From 0 to 5 min, the initial pressure is 5 - 10 kPa, the pressing plate of the pressing device descends at a speed of 0.5 - 1 cm / min, and continuous pressing is performed 3 times, with an interval of 30 s each time; S2. Second-stage pressing: From 5 to 10 min, the pressure is increased to 15 - 20 kPa, the pressing plate of the pressing device descends at a speed of 0.2 - 0.5 cm / min, and the interval time is 1 min; S3. Third-stage pressing: From 10 to 15 min, maintaining a pressure of 20 kPa, pulse pressing is adopted, with a cycle of pressing for 2 min / releasing for 30 s; S4. Fourth-stage pressing: At 15 - 20 minutes, quickly increase the pressure to 30 - 35 kPa, raise the platen speed to 2 cm / min, and the single pressing lasts for 5 minutes; S5. Fifth-stage pressing: At 20 - 25 minutes, the peak pressure is 40 - 45 kPa. With the assistance of surface hot air, maintain the temperature at 50 - 60 °C for rapid skin formation.

[0009] The pressing device includes a pressing box and a hydraulic component. The pressing box includes a box body (1) and a platen. The hydraulic component is vertically connected to the upper side of the platen. The platen includes a connecting frame and a movable bottom surface. The movable bottom surface includes a number of adjacent strip plates. There are spring support rods connected between the connecting frame and the strip plates. An incremental extrusion component is arranged inside the connecting frame. The incremental extrusion component is arranged along the length direction of the connecting frame. When the incremental extrusion component rotates, it can sequentially extrude a number of the strip plates along the length direction of the connecting frame, squeezing the water in the tofu downward and toward the drainage side; The incremental extrusion component includes a connecting shaft and a number of groups of extrusion parts. Each group of extrusion parts includes two parallel extrusion discs. The two extrusion discs are respectively arranged on the upper sides of the two long sides of the strip plate. When the connecting shaft rotates, the extrusion disc on the far drainage side contacts the strip plate first, and the extrusion disc on the near drainage side contacts the strip plate later.

[0010] As an optimization, the extrusion disc is fan-shaped, the extrusion disc is coaxially arranged with the connecting shaft, and the central angles of the two extrusion discs of each group of extrusion parts are different; From the far drainage side to the near drainage side, the central angle of the extrusion disc gradually decreases.

[0011] As an optimization, one end of the connecting shaft is configured with a driving component. The driving component includes a driving motor and a connecting belt. One end of the connecting shaft is provided with a connecting gear. The output shaft of the driving motor is provided with a driving gear. The connecting belt is sleeved outside the connecting gear and the driving gear.

[0012] As an optimization, each strip plate is configured with at least 4 spring support rods. The spring support rods are rotatably connected to the strip plate. The spring support rods on the near drainage side can slide relative to the connecting frame; When the strip plate is on the upper side of the bottom surface of the connecting frame, the spring support rods are in a shortened state.

[0013] As an optimization, a drainage port is provided at the bottom of one side in the length direction of the pressing box. The central angle of the extrusion part near the drainage port is smaller than that of the extrusion part far from the drainage port.

[0014] As an optimization, the diameters of several of the extrusion members are the same, and the connecting shaft is disposed adjacent to the strip-shaped plate. When extruding the tofu, the distance between the connecting shaft and the adjusting plate is less than the diameter of the extrusion member.

[0015] As an optimization, the hydraulic component includes a telescopic cylinder, and the telescopic cylinder is vertically connected to the upper part of the connecting frame body.

[0016] The beneficial effects of this solution are as follows: The preparation process of this application realizes the directional discharge of moisture through a five-stage gradient pressing system. During the pressing process, it is slow first and then urgent, with progressive drainage, which can effectively avoid premature skin formation on the surface of the tofu, ensure the efficient discharge and uniform distribution of moisture, and finally form a dense tissue structure through rapid high-pressure pressing, avoiding the loose internal structure of the old tofu and forming a high-quality old tofu with an epidermis thickness ≥ 0.8 mm and a central water content of 68 - 72%.

[0017] The pressing device of this application can realize the sequential pressing of the tofu from top to bottom along the length direction of the pressing device, achieving the "water driving" of the old tofu, squeezing the moisture in the old tofu to the drainage side, and avoiding the moisture back-suction after the pressing device is released; The progressive extrusion component forms a crawler-like extrusion effect by setting an extrusion disk group with different central angles. The fan-shaped extrusion disk can ensure the linear transmission of pressure and avoid local stress concentration. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is an axonometric schematic diagram of the pressing device of the present invention.

[0019] Figure 2 It is a front view schematic diagram of the pressing device of the present invention.

[0020] Figure 3 It is a bottom axonometric schematic diagram of the pressing device of the present invention.

[0021] Figure 4 It is an axonometric schematic diagram of the connection structure between the pressing plate and the hydraulic component of the present invention.

[0022] Figure 5 It is a front view schematic diagram of the connection structure between the pressing plate and the hydraulic component of the present invention.

[0023] Figure 6 For the present invention Figure 5 A - A sectional structure schematic diagram.

[0024] Figure 7 It is an axonometric schematic diagram of the position structure between the movable bottom surface and the progressive extrusion component of the present invention.

[0025] Figure 8 It is a rear axonometric schematic diagram of the position structure between the movable bottom surface and the progressive extrusion component of the present invention.

[0026] Figure 9 This is a schematic diagram of the overall structure of the progressive extrusion component of the present invention.

[0027] Figure 10 This is an axonometric schematic diagram of the progressive extrusion component of the present invention.

[0028] Among them, 1. Box body, 2. Connecting frame body, 3. Strip plate, 4. Spring support rod, 5. Connecting shaft, 6. Extrusion disc, 7. Driving motor, 8. Connecting belt, 9. Drainage port, 10. Telescopic cylinder. Specific implementation method

[0029] A preparation process for old tofu with staged pressing includes five-stage pressure control. Among them, in the first three stages, a pressing device is used for slow progressive pressing with a pressure ≤ 20 Kpa, and in the last two stages, rapid high-pressure pressing is used with a pressure ≥ 30 kPa. The pressing time for the five stages is 25 ± 2 min.

[0030] The third stage is a pulse pressing mode, and the pressing / release time ratio is 4:1.

[0031] The specific content of the five-stage pressure control is as follows: S1. First-stage pressing: At 0 - 5 min, the initial pressure is 5 - 10 kPa, the pressing plate of the pressing device descends at a speed of 0.5 - 1 cm / min, and it is continuously pressed 3 times with an interval of 30 s each time; S2. Second-stage pressing: At 5 - 10 min, the pressure is increased to 15 - 20 kPa, the pressing plate of the pressing device descends at a speed of 0.2 - 0.5 cm / min, and the interval time is 1 min; S3. Third-stage pressing: At 10 - 15 min, maintain a pressure of 20 kPa and use pulse pressing, with a cycle of pressing for 2 min / releasing for 30 s; S4. Fourth-stage pressing: At 15 - 20 min, quickly pressurize to 30 - 35 kPa, the pressing plate speed is increased to 2 cm / min, and each single pressing lasts for 5 min; S5. Fifth-stage pressing: At 20 - 25 min, the peak pressure is 40 - 45 kPa, with the assistance of surface hot air, the temperature is maintained at 50 - 60 °C, and rapid skin formation is carried out.

[0032] The examples use the above-mentioned preparation process for old tofu with staged pressing and the pressing device of the present application to prepare old tofu. Comparative example 1 uses the preparation process of the present application and produces and prepares old tofu through an existing one-time pressing device; Comparative example 2 uses a one-time pressing method and an existing one-time pressing device to prepare old tofu; Comparative example 3 uses a two-stage pressing method and the pressing device of the present application to produce and prepare dried tofu. The specific content and product test results are as follows:

[0033] In Examples 1 - 3, the pressing time was 25 min, with 5 min for each of the five stages. In Comparative Example 2, it was pressed at 35 kPa for 25 min, and in Comparative Example 3, it was pressed at 20 kPa for 15 min and then at 45 kPa for 10 min.

[0034] As can be seen from the above table, the skin thickness of the old tofu obtained by the staged pressing process and the pressing device of the present application is moderate, and the central moisture content reaches about 70%. When Comparative Example 2 uses the traditional one - stage pressing method and an ordinary pressing device, the skin of the obtained old tofu is too thick, but the central moisture content is too high, with the outside being dry and the inside being wet. Comparative Example 3 uses the existing two - stage pressing method and the pressing device of the present application, and the skin of the obtained old tofu is relatively low, and the water content also shows a significant decrease compared to Comparative Example 2.

[0035] Therefore, through the staged pressing process and the pressing device of the present application, the water content of the old tofu can be effectively reduced, and old tofu with a suitable skin thickness can be obtained.

[0036] As Figures 1-10 shown, the pressing device includes a pressing box and a hydraulic component. The pressing box includes a box body 1 and a pressing plate. The hydraulic component is vertically connected to the upper side of the pressing plate. The pressing plate includes a connecting frame body 2 and a movable bottom surface. The movable bottom surface includes a plurality of adjacent strip - shaped plates 3. A spring support rod 4 is connected between the connecting frame body 2 and the strip - shaped plate 3. An incremental extrusion component is arranged inside the connecting frame body 2. The incremental extrusion component is arranged along the length direction of the connecting frame body 2. When the incremental extrusion component rotates, it can sequentially extrude the plurality of strip - shaped plates 3 along the length direction of the connecting frame body 2, squeezing the water in the tofu downward and toward the drainage side; The incremental extrusion component includes a connecting shaft 5 and a plurality of groups of extrusion parts. Each group of extrusion parts includes two parallel extrusion disks 6. The two extrusion disks 6 are respectively arranged on the upper sides of the two long sides of the strip - shaped plate 3. When the connecting shaft 5 rotates, the extrusion disk 6 on the far drainage side contacts the strip - shaped plate 3 first, and the extrusion disk 6 on the near drainage side contacts the strip - shaped plate 3 later.

[0037] The far drainage side is the side far from the drainage flow direction, and the near drainage side is the side close to the drainage flow direction. For example, if the water flows from left to right during the extrusion process, then the left side is the far drainage side and the right side is the near drainage side.

[0038] The extrusion disk 6 can be fixedly sleeved on the connecting shaft 5 or integrally formed with the connecting shaft 5. When the connecting shaft 5 rotates, it drives a plurality of extrusion disks 6 to rotate simultaneously. The extrusion disk 6 with a larger central angle can contact the strip - shaped plate 3 earlier and push the strip - shaped plate 3 downward to extrude the tofu.

[0039] To enable the strip plate 3 to be stably extruded downward, multiple parallel progressive extrusion components can be arranged inside the connecting frame 2, and the strip plate 3 is stably extruded by the multiple progressive extrusion components.

[0040] As Figure 9 and Figure 10 shown, the extrusion disc 6 is fan-shaped, the extrusion disc 6 is coaxially arranged with the connecting shaft 5, and the central angles of the two extrusion discs 6 of each group of extrusion members are different; From the far drainage side to the near drainage side, the central angle of the extrusion disc 6 gradually decreases.

[0041] The central angles of each extrusion disc 6 are different, and one ends of the multiple extrusion discs 6 are aligned, so that the other ends of the multiple extrusion discs 6 are distributed in a stepped manner. When the connecting shaft 5 rotates, the stepped extrusion discs 6 are in contact with the strip plate 3 in sequence.

[0042] As Figure 10 shown, one end of the connecting shaft 5 is configured with a driving component, the driving component includes a driving motor 7 and a connecting belt 8, a connecting gear is arranged at one end of the connecting shaft 5, a driving gear is arranged on the output shaft of the driving motor 7, and the connecting belt 8 is sleeved outside the connecting gear and the driving gear.

[0043] The connecting belt 8 can be meshed with the driving gear and the connecting gear, and the connecting shaft 5 is driven to rotate synchronously through the connecting belt 8. At the same time, to ensure the stability of the rotation of the connecting shaft 5, a support seat should be configured inside the connecting frame 2 so that the connecting shaft 5 is rotatably connected to the support seat.

[0044] As Figure 3 and Figure 7 shown, each strip plate 3 is configured with at least 4 spring support rods 4, the spring support rods 4 are rotatably connected to the strip plate 3, and the spring support rods 4 on the near drainage side can slide relative to the connecting frame 2; When the strip plate 3 is located above the bottom surface of the connecting frame 2, the spring support rods 4 are in a shortened state.

[0045] The strip plate 3 can pass through the bottom of the connecting frame 2 and be extruded downward. Since the two extrusion discs 6 corresponding to the strip plate 3 are extruded downward at different times, the strip plate 3 will rotate when being extruded downward. Therefore, the spring support rods 4 on the near drainage side will have a certain amount of relative displacement with the strip plate 3. Correspondingly, the strip plate 3 should be provided with a sliding groove so that the lower ends of the spring support rods 4 can slide relative to the sliding groove.

[0046] As Figure 1 shown, a drainage port 9 is provided at the bottom of one side in the length direction of the pressing box, and the central angle of the extrusion member near the drainage port 9 is smaller than that of the extrusion member far from the drainage port 9.

[0047] As Figure 8 shown, the diameters of several of the extrusion members are the same. The connecting shaft 5 is disposed adjacent to the strip plate 3. When extruding the tofu, the distance between the connecting shaft 5 and the adjusting plate is less than the diameter of the extrusion member.

[0048] As Figure 1 shown, the hydraulic assembly includes a telescopic cylinder 10 which is vertically connected to the upper part of the connecting frame 2.

[0049] Usage method: When the pressing device of the present application is specifically used, first, the pressing plate is pressed downward by the telescopic cylinder 10; When the pressing plate is pressed against the tofu, the strip plate 3 is received inside the connecting frame 2; The driving motor 7 drives the connecting shaft 5 to rotate, and the connecting shaft 5 drives the extrusion disc 6 to rotate. When the extrusion disc 6 contacts the strip plate 3, the strip plate 3 is pushed downward to be extruded, and the telescopic cylinder 10 synchronously extends to improve the extrusion effect on the tofu; Since the sizes of the extrusion discs 6 corresponding to each strip plate 3 are different, and the extrusion disc 6 gradually decreases from the drainage side to the water inlet side, the plurality of strip plates 3 are sequentially extruded, so as to realize extruding the water in the tofu in the direction of the drainage port 9 to promote the discharge of moisture.

[0050] To ensure the efficient operation of the device, a limiting groove and other structures can also be provided inside the connecting frame 2, so that the strip plate 3 can move downward along the limiting groove during the downward pressing process to prevent the strip plate 3 from shaking. Correspondingly, the bottom of the connecting frame 2 can be an opening, or a high-density filter cloth or filter membrane with a certain elasticity can be provided to limit the top of the tofu to prevent the tofu from being damaged under pressure.

[0051] The above specific embodiments are only specific cases of the present invention. The patent protection scope of the present invention includes, but is not limited to, the product forms and styles of the above specific embodiments. Any preparation process of old tofu with a staged pressing and its pressing device that conforms to the claims of the present invention and any appropriate changes or modifications made by those of ordinary skill in the corresponding technical field shall fall within the patent protection scope of the present invention.

Claims

1. A process for preparing old tofu by pressing in stages, characterized in that: It includes five-stage pressure control, wherein the first three stages use a pressing device for slow progressive pressing with a pressure of ≤20KPa, and the last two stages use fast high-pressure pressing with a pressure of ≥30kPa. The five-stage pressing time is 25±2min.

2. The process for preparing old tofu by staged pressing according to claim 1, characterized in that: The third stage is a pulsed suppression mode with a suppression / release time ratio of 4:

1.

3. The process for preparing old tofu by staged pressing according to claim 1, characterized in that: The specific contents of the five-stage pressure control are as follows: S1. The first stage of pressing: 0-5min, the initial pressure is 5-10kPa, the pressing plate of the pressing device descends at a speed of 0.5-1cm / min, and the pressing is repeated 3 times, each time with an interval of 30s; S2. Second stage of pressing: 5-10 minutes later, the pressure is increased to 15-20 kPa, the pressing plate of the pressing device descends at a speed of 0.2-0.5 cm / min, and the interval time is 1 minute; S3. The third stage of pressing: 10-15 minutes, maintain 20kPa pressure, use pulse pressing, press for 2 minutes / release for 30 seconds cycle; S4. The fourth stage of pressing: at 15-20 minutes, the pressure is quickly increased to 30-35 kPa, the pressing speed is increased to 2 cm / min, and a single pressing lasts for 5 minutes; S5. The fifth stage of pressing: at 20-25 minutes, the peak pressure is 40-45 kPa, with the assistance of surface hot air, the temperature is maintained at 50-60℃ for rapid crusting.

4. A tofu pressing device, used in the tofu preparation process of stepwise pressing according to any one of claims 1 to 3, comprising a pressing box and a hydraulic assembly, wherein the pressing box comprises a box body (1) and a pressing plate, and the hydraulic assembly is vertically connected to the upper side of the pressing plate, characterized in that: The pressing plate comprises a connecting frame (2) and a movable bottom surface, the movable bottom surface comprises a plurality of adjacently arranged strip plates (3), a spring support rod (4) is connected between the connecting frame (2) and the strip plates (3), a progressive extrusion assembly is arranged inside the connecting frame (2), the progressive extrusion assembly is arranged along the length direction of the connecting frame (2), and when the progressive extrusion assembly rotates, it can sequentially extrude the plurality of strip plates (3) along the length direction of the connecting frame (2), thereby squeezing the moisture in the tofu downward and toward the drainage side; The progressive extrusion assembly comprises a connecting shaft (5) and a plurality of groups of extrusion parts, each group of extrusion parts comprises two extrusion discs (6) arranged in parallel, the two extrusion discs (6) being arranged on the upper sides of the two long sides of the strip plate (3) respectively, and when the connecting shaft (5) rotates, the extrusion disc (6) on the far drainage side contacts the strip plate (3) first, and the extrusion disc (6) on the near drainage side contacts the strip plate (3) later.

5. The old tofu pressing device according to claim 4, characterized in that: The extrusion disk (6) is fan-shaped, the extrusion disk (6) is coaxially arranged with the connecting shaft (5), and the central angles of the two extrusion disks (6) of each group of the extrusion parts are different; From the far drainage side to the near drainage side, the central angle of the squeezing disc (6) gradually decreases.

6. The old tofu pressing device according to claim 4, characterized in that: One end of the connecting shaft (5) is provided with a driving assembly, and the driving assembly includes a driving motor (7) and a connecting belt (8). One end of the connecting shaft (5) is provided with a connecting gear, and the output shaft of the driving motor (7) is provided with a driving gear, and the connecting belt (8) is sleeved on the outside of the connecting gear and the driving gear.

7. The old tofu pressing device according to claim 4, characterized in that: Each of the strip plates (3) is equipped with at least four spring support rods (4), the spring support rods (4) are rotatably connected to the strip plates (3), and the spring support rods (4) near the drainage side can slide relative to the connection frame (2); When the strip plate (3) is located on the upper side of the bottom surface of the connecting frame (2), the spring support rod (4) is in a shortened state.

8. The old tofu pressing device according to claim 4, characterized in that: A drainage port (9) is provided at the bottom of one side in the length direction of the pressing box, and the center angle of the extrusion piece close to the drainage port (9) is smaller than the center angle of the extrusion piece far from the drainage port (9).

9. The old tofu pressing device according to claim 4, characterized in that: The diameters of the plurality of extrusion members are the same, the connection shaft (5) and the strip plate (3) are arranged adjacent to each other, and when the tofu is extruded, the distance between the connection shaft (5) and the adjustment plate is smaller than the diameter of the extrusion member.

10. The old tofu pressing device according to claim 4, characterized in that: The hydraulic assembly comprises a telescopic cylinder (10), and the telescopic cylinder (10) is vertically connected to the upper part of the connecting frame (2).

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